Layered cathodes for lithium-ion battery, including LiCo1–x–yNixMnyO2 and xLi2MnO3·(1–x)LiMO2 (M = Mn, Ni, and Co), are attractive for large-scale applications such as electric vehicles, because they can deliver additional specific capacity when the end of charge voltage is improved to over 4.2 V. However, operation under a high voltage might cause capacity decaying of layered cathodes during cycling. The failure mechanisms that have been given, up to date, include the electrolyte oxidation decomposition, the Ni, Co, or Mn ion dissolution, and the phase transformation. In this work, we report a new mechanism involving the exfoliation of layered cathodes when the cathodes are performed with deep cycling under 4.5 V in the electrolyte consisting of carbonate solvents and LiPF6 salt. Additionally, an electrolyte additive that can form a cathode interface film is applied to suppress this exfoliation. A representative layered cathode, LiCoO2, and an interface film-forming additive, dimethyl phenylphosphonite (DMPP), are selected to demonstrate the exfoliation and the protection of layered structure. When evaluated in half-cells, LiCoO2 exhibits a capacity retention of 24% after 500 cycles in base electrolyte, but this value is improved to 73% in the DMPP-containing electrolyte. LiCoO2/graphite full cell using DMPP behaves better than the Li/LiCoO2 half-cell, delivering an initial energy density of 700 Wh kg –1 with an energy density retention of 82% after 100 cycles at 0.2 C between 3 and 4.5 V, as compared to 45% for the cell without using DMPP.Keywords: anion insertion; electrolyte additive; exfoliation of layered structure; interface film; lithium cobalt oxide;

•There exists an interaction between layered lithium-rich oxide and electrolyte.•Detrimental products might be formed from electrolyte oxidation by active oxygen.•TEP as electrolyte additive traps active oxygen and is oxidized preferentially.•Cathode film is formed from TEP oxidation and mitigates electrolyte decomposition.Electrolyte additives have been found to be effective for the cyclic stability improvement of layered lithium-rich oxide (LRO), which is ascribed to the formation of cathode films derived from the preferential oxidation of the electrolyte additives. However, the detailed mechanism on the formation of the cathode film is unclear. This paper uncovers the interaction between LRO and additive-containing electrolyte through theoretical calculations, electrochemical measurements and physical characterizations. A representative LRO, Li1.2Mn0.54Ni0.13Co0.13O2, is synthesized, and an electrolyte, 1 M LiPF6 in EC/DMC (1/2, in volume) using triethyl phosphite (TEP) as additive, is considered. Charge/discharge tests demonstrate that LRO suffers severe capacity fading and TEP can significantly improve the cyclic stability of LRO. Characterizations from SEM and TEM demonstrate that a cathode film exists on the LRO after cycling in the TEP-containing electrolyte. The theoretical calculations suggest that TEP traps the active oxygen and is then oxidized on LRO preferentially compared to the electrolyte, forming the cathode film. The further characterizations from FTIR and GC, confirm that the preferential combination of TEP with active oxygen is beneficial for the suppression of oxygen evolution, and that the resulting cathode film can suppress the electrolyte decomposition and protect LRO from destruction.

•FN can improves the cyclic stability and suppresses the self-discharge of LiCoO2.•There is a stronger interaction of Co3+ in LiCoO2 with FN than carbonate molecules.•A protective cathode interphase is formed from the preferential oxidation of FN.•The cathode interphase maintains the structural integrity of LiCoO2.The specific capacity of lithium-ion battery with lithium cobalt oxide as cathode depends on the upper limitation voltage for charge/discharge cycling, but this oxide tends to be destructed structurally when it is cycled in carbonate-based electrolyte under high voltage. We report a novel electrolyte additive, fumaronitrile (FN, CNCHCHCN), which can maintain the structural integrity of lithium cobalt oxide. Electrochemical measurements indicate that lithium cobalt oxide exhibits poor cyclic stability when it is cycled under 4.5 V (vs. Li/Li+) and the charged cathode suffers serious self-discharge in a base electrolyte, 1.0 mol L−1 LiPF6 in EC/EMC/DEC (3:5:2, by weight). These issues can be overcome effectively by adding 0.5% FN into the base electrolyte. Physical and chemical characterizations demonstrate that the poor cyclic stability and self-discharge of lithium cobalt oxide result from its structural destruction caused by HF formed from electrolyte decomposition, and FN yields a protective cathode interphase film which maintains the structural integrity of lithium cobalt oxide.

•SE is an effective electrolyte additive for high temperature application of LiNi0.5Mn1.5O4.•A protective film can be formed on LiNi0.5Mn1.5O4 due to preferential oxidation of SE.•The film can suppress the dissolution of transition metal ions from LiNi0.5Mn1.5O4.Electrolyte additives are necessary for the application of high potential cathode in high energy density lithium ion batteries, especially at elevated temperature. However, the electrolyte additives that can effectively suppress the dissolution of transition metal ions from cathode have seldom been developed up to date. In this work, we propose a novel electrolyte additive, trimethylsilylcyclopentadiene (SE), for high temperature application of a representative high potential cathode, lithium nickel manganese oxide (LiNi0.5Mn1.5O4). It is found that the dissolution of Mn and Ni from LiNi0.5Mn1.5O4 can be effectively suppressed by applying SE. With applying 0.25% SE, the dissolved amount of Mn and Ni is decreased by 97.4% and 98%, respectively, after 100 cycles at 55 °C. Correspondingly, the cyclic performance of LiNi0.5Mn1.5O4 is significantly improved. Physical characterizations and electrochemical measurements show that SE can be preferentially oxidized and generate a protective film on LiNi0.5Mn1.5O4. The resulting film inhibits the electrolyte decomposition and the transition metal ion dissolution.

Diethyl phenylphosphonite (DEPP) is used as a novel electrolyte additive to improve the cyclability of spinel LiMn2O4 upon cycling at elevated temperature (55 °C). The charge/discharge cycling stability results indicate that capacity retention of Li/LiMn2O4 cell is significantly improved from 40 to 78% at a rate of 1C (1C = 120 mAh g−1) when 1.0 wt% DEPP is added to the baseline electrolyte (1.0 M LiPF6 in EC/EMC/DEC (3:5:2, vol.%)) after 450 cycles at 55 °C. This improvement can be attributed to the preferential oxidation of DEPP to that of the baseline electrolyte and the subsequent formation of a protective film on the cathode surface. This passivation film suppresses detrimental electrolyte decomposition and in turn protects LiMn2O4 from further decomposition. Molecular energy level calculations, linear sweep voltammetry, and cyclic voltammetry results confirm that DEPP is oxidized on the cathode surface prior to the oxidation of carbonate solvents. Electrochemical impedance spectroscopy illustrates that the the cathode interfacial film generated from DEPP oxidation is more stable and robust than that of the surface film yielded from the baseline electrolyte’s decomposition. Ex situ surface-characterization results further support the claim that DEPP incorporation in the electrolyte suppresses the electrolyte oxidation at elevated temperature and the decomposition of LiMn2O4 cathode material as well.

•Cyclability of LiCoO2/graphite full cell is improved notably by using TFTPN.•TFTPN is more easily oxidized on cathode or reduced on anode than electrolyte.•Protective interphase films formed simultaneously on cathode and anode by TFTPN.A novel electrolyte additive, tetrafluoroterephthalonitrile (TFTPN), is proposed to improve the cyclic stability of lithium cobalt oxide (LiCoO2)/graphite lithium-ion full cells up to 4.4 V. Electrochemical measurements indicate that TFTPN can be reduced on graphite electrode and oxidized on LiCoO2 electrode preferentially compared to the baseline electrolyte, 1.0 M LiPF6 in EC/DEC/EMC (1/1/1, in weight), and thus improves the cyclic stability of graphite/Li and LiCoO2/Li half cells, respectively. Further charge/discharge tests demonstrate that the cyclic stability of LiCoO2/graphite full cell can be significantly improved by TFTPN. A high capacity retention of 91% is achieved for the full cell using 0.5% TFTPN-containing electrolyte after cycling at 0.5C between 3.0 and 4.4 V for 300 cycles, compared to the 79% for that using the baseline electrolyte. This effect is attributed to the simultaneously formed protective interphase films on graphite and LiCoO2 by TFTPN due to its preferential reduction or oxidation. The resulting interphase films are verified by physical characterizations and theoretical calculations.Download high-res image (204KB)Download full-size image

In this paper, we design a novel gel polymer electrolyte (GPE), based on polyethylene (PE) supported poly(butyl methacrylate-acrylonitrile-styrene) (P(BMA-AN-St)) terpolymer reinforced by doping 10 wt.% nano-SiO2, to be possible application in high voltage lithium ion battery. The physical characterization indicates that P(BMA-AN-St)/SiO2/PE membrane has multi-layered and cross-linked network structure with the pore diameter of about 1 μm, leading to the highest electrolyte uptake ability of 257% compared with the value of 118% for PE support. Electrochemical performance exhibits that the corresponding GPE presents highest ionic conductivity of 1.9 × 10−3 S cm−1 at room temperature and the improved oxidative stability from 4.2 V (PE support saturated with liquid electrolyte) to 5.2 V (vs. Li/Li+). Thus, the high voltage cathode LiNi0.5Mn1.5O4 using nano-SiO2 doped GPE presents excellent cyclic stability and rate performance, which retains 93.0% of its initial discharge capacity after 150 cycles at 0.2C rate and keeps 95.0% discharge capacity at 2C rate of that at 0.1C rate, while PE support saturated with liquid electrolyte has 87.9% capacity retention after 150 cycles and with the rate capacity value of 86.8% at the same rate test condition.

•TMB and TEB effective improve the cyclic stability of LNMO at high voltage.•The performance of LNMO with TMB-containing electrolyte is superior to that of TEB.•LNMO shows catalytic effect on the oxidation reaction of TEB.•The film generated in TMB shows better ability on suppressing LNMO shedding than TEB.Trimethyl borate (TMB) and triethyl borate (TEB) are used as film-forming electrolyte additives for high voltage Lithium nickel manganese oxide (LNMO) cathode. DFT calculation and initial charge curve of LNMO reveal that the oxidation activity of TEB is higher than that of TMB. Addition of 2% TMB and 2% TEB effectively improve the capacity retention of high voltage LNMO from 23.4% to 85.3% and 72.6% after 600 cycles, respectively. The film generated in TMB-containing electrolyte shows better ability on suppressing the LNMO shedding in comparison with that of TEB, resulting in higher capacity retention of LNMO in TMB-containing electrolyte at high voltage. The superior performance of LNMO with TMB-containing electrolyte should be ascribed to its less intense film-forming reaction which generates a denser protective surface film on LNMO surface. However, why LNMO shows catalyzation effect on TEB oxidation but not on TMB is unclear, which needs further intensive investigation.Download high-res image (180KB)Download full-size image

•Tripropyl borate (TPB) is able to stabilize the LiMn2O4/carbonate-based electrolyte interface.•A protective cathode film is formed on LiMn2O4 due to the preferential oxidation of TPB.•Unnecessary electrolyte decomposition products can be reduced by applying TPB.•The stabilized interface benefits the cyclic stability and avoids the self-discharge of LiMn2O4.A simple boron-containing molecule, tripropyl borate (TPB), is used as an electrolyte additive to stabilize the interface between spinel lithium manganese oxide (LiMn2O4) and carbonate-based electrolyte under elevated temperature. Electrochemical measurements indicate that the cyclic stability of LiMn2O4 electrode can be significantly improved by TPB. The capacity retention of LiMn2O4 at 1C after 200 cycles under 55 °C is improved from 47% to 74% by adding 3% TPB into a standard electrolyte (1.0 mol L−1 LiPF6-EC/EMC/DEC (3/5/2, in weight)). Most importantly, the self-discharge of LiMn2O4 under 55 °C, which takes place dramatically in the standard electrolyte, is effectively suppressed in 3% TPB-containing electrolyte. Theoretical calculations and physical characterizations demonstrate that a protective cathode electrolyte interface (CEI) film is formed on LiMn2O4 from the preferential oxidation of TPB, which suppresses the oxidation decomposition of the standard electrolyte. Due to the incorporation of boron, the CEI film formed from TPB is beneficial to the rate capability of LiMn2O4.

•Prop-1-ene-1,3-sultone is used for forming interphase on porous Mn2O3 nanocubes.•The interphase protects Mn2O3 nanocubes from structural destruction.•The enforced Mn2O3 exhibits excellent performance as anode of lithium ion battery.We present a novel configuration for stabilizing manganese oxide as anode of high energy density lithium ion battery. Porous Mn2O3 nanocubes were developed with cubic MnCO3 as precursor and coated with a solid electrolyte interphase (SEI) by applying an electrolyte additive, prop-1-ene-1,3-sultone (PES). Discharge-charge tests demonstrate that the resulting anode exhibits excellent cyclic stability. Electrochemical and physical characterizations indicate that PES is easily reducible on Mn2O3 forming a protective SEI, which maintains the structural integrity of Mn2O3 particles. The porosity of the cubes and the SEI on the particles co-contribute to the improved cyclic stability of the resulting anode.

AbstractTo meet future market demand, developing new structured materials for electrochemical energy conversion and storage systems is essential. Hierarchically porous micro-/nanostructures are favorable for designing such high-performance materials because of their unique features, including: i) the prevention of nanosized particle agglomeration and minimization of interfacial contact resistance, ii) more active sites and shorter ionic diffusion lengths because of their size compared with their large-size counterparts, iii) convenient electrolyte ingress and accommodation of large volume changes, and iv) enhanced light-scattering capability. Here, hierarchically porous micro-/nanostructures produced by morphology-conserved transformations of metal-based precursors are summarized, and their applications as electrodes and/or catalysts in rechargeable batteries, supercapacitors, and solar cells are discussed. Finally, research and development challenges relating to hierarchically porous micro-/nanostructures that must be overcome to increase their utilization in renewable energy applications are outlined.

Lithium manganese oxide (LiMn2O4) is one of the most promising cathodes for lithium ion batteries because of its abundant resources and easy preparation. However, its poor cyclability, especially under elevated temperature, limits its application on a large scale. In this work, it is reported that the cyclability of LiMn2O4 can be significantly improved by applying 4-(trifluoromethyl)benzonitrile (4-TB) as an electrolyte additive. Charge/discharge tests indicate that the capacity retention of LiMn2O4 after 450 cycles at 1C and 55 °C in a standard electrolyte, 1 M LiPF6 in EC/EMC/DEC (3 : 5 : 2, in weight), is improved from 19% to 69%. Further electrochemical and physical characterization demonstrates that 4-TB can, on the one hand, be electrochemically oxidized preferentially compared to the standard electrolyte, which generates a protective interphase film on LiMn2O4. On the other hand, 4-TB can effectively combine with protonic impurities, which inhibits the thermal decomposition of the electrolyte. This dual-functionality of 4-TB contributes to the significantly improved cyclability of LiMn2O4.

In this paper, MnO2 nanoboxes coated with poly(3,4-ethylenedioxythiophene) film (denoted as MnO2@PEDOT) are investigated as an anode material in lithium-ion batteries. The MnO2 nanoboxes are developed through the surface chemical oxidation decomposition of MnCO3 cubes and the subsequent removal of their remaining cores. PEDOT is coated on the surface of MnO2 nanoboxes via in situ polymerization of 3,4-ethylenedioxythiophene. The charge–discharge tests demonstrate that this special configuration endows the resulting MnO2@PEDOT with remarkable electrochemical performances, that is a reversible capacity of 628 mA h g−1 after 850 cycles at a current density of 1000 mA g−1 and a rate capacity of 367 mA h g−1 at 3000 mA g−1. The results indicate that the nanoboxes provide the paths for Li-ion diffusion, the reaction sites for Li-ion intercalation/deintercalation and the space to buffer the volume change during the charge–discharge process, while the conductive polymer ensures the structural stability and improves the electronic conductive property of MnO2.

Nanolayered lithium-rich oxide doped with spinel phase is synthesized by acidic sucrose-assistant sol–gel combustion and evaluated as the cathode of a high-energy-density lithium ion battery. Physical characterizations indicate that the as-synthesized oxide (LR-SN) is composed of uniform and separated nanoparticles of about 200 nm, which are doped with about 7% spinel phase, compared to the large aggregated ones of the product (LR) synthesized under the same condition but without any assistance. Charge/discharge demonstrates that LR-SN exhibits excellent rate capability and cyclic stability: delivering an average discharge capacity of 246 mAh g–1 at 0.2 C (1C = 250 mA g–1) and earning a capacity retention of 92% after 100 cycles at 4 C in the lithium anode-based half cell, compared to the 227 mA g–1 and the 63% of LR, respectively. Even in the graphite anode-based full cell, LR-SN still delivers a capacity of as high as 253 mAh g–1 at 0.1 C, corresponding to a specific energy density of 801 Wh kg–1, which are the best among those that have been reported in the literature. The separated nanoparticles of the LR-SN provide large sites for charge transfer, while the spinel phase doped in the nanoparticles facilitates lithium ion diffusion and maintains the stability of the layered structure during cycling.Keywords: cathode; layered lithium-rich oxide; lithium ion battery; nanoparticles; spinel phase doping

Phenyl vinyl sulfone (PVS) as a novel electrolyte additive is used to construct a protective interface film on layered lithium-rich cathode. Charge–discharge cycling demonstrates that the capacity retention of Li(Li0.2Mn0.54Ni0.13Co0.13)O2 after 240 cycles at 0.5 C between 2.0 and 4.8 V (vs Li/Li+) reaches about 80% by adding 1 wt % PVS into a standard (STD) electrolyte, 1.0 M LiPF6 in EC/EMC/DEC (3/5/2 in weight). This excellent performance is attributed to the special molecular structure of PVS, compared to the additives that have been reported in the literature. The double bond in the molecule endows PVS with preferential oxidizability, the aromatic ring ensures the chemical stability of the interface film, and the sulfur provides the interface film with ionic conductivity. These contributions have been confirmed by further electrochemical measurements, theoretical calculations, and detailed physical characterizations.Keywords: cyclic stability; electrolyte additive; layered lithium-rich oxide; molecular structure; phenyl vinyl sulfone

•SDM is investigated as an electrolyte additive for LiNi0.5Mn1.5O4 cathodes.•The cycling performance is enhanced with appropriate amount addition of SDM.•The surface layer derived from SDM on the cathode is more stable and robust.•Dissolution of Mn and Ni of LiNi0.5Mn1.5O4 can be mitigated by adding SDM.A novel electrolyte additive, 1,1′-sulfonyldiimidazole (SDM), is firstly reported to improve the cycling performance of LiNi0.5Mn1.5O4 at high voltage and elevated temperature (55 °C). Linear sweep voltammetry (LSV), initial differential capacity vs. voltage, and computation results indicate that SDM is oxidized at a lower potential than the solvents of the electrolyte. Coulombic efficiency and capacity retention of a Li/LiNi0.5Mn1.5O4 cell can be significantly enhanced in the presence of SDM, and moreover cells with SDM deliver lower impedance after 100 cycles at elevated temperature. To better understand the functional mechanism of the enhanced performance with incorporation of SDM in the electrolyte, ex-situ analytical techniques, including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and inductively coupled plasma mass spectrometry (ICP-MS) are employed to gain insight into the reaction mechanism of SDM on the LiNi0.5Mn1.5O4 electrode at high voltage and elevated temperature (55 °C). Surface analysis reveals that the improved electrochemical performance of the cells can be ascribed to the highly stable surface layer generated by SDM, which thus mitigates the detrimental decomposition of the electrolyte occurring and stabilizes the interphase of spinel LiNi0.5Mn1.5O4 cathode while cycling at high voltage and elevated temperature.

•ZnMn2(CO3)3 nanoshpere was developed as precursor through a facile microemulsion method.•ZnMn2O4 from the thermal decomposition of ZnMn2(CO3)3 adopts a porous nanosphere structure.•The porous ZnMn2O4 nanoshpere exhibits excellent rate capability and cyclic stability.Porous ZnMn2O4 nanospheres are synthesized through a facile microemulsion method. Crystal structure, morphology and electrochemical performance of the product as anode of lithium ion battery were investigated with FESEM, TEM, HRTEM, BET, XPS, XRD, CV, EIS, and charge/discharge test, with a comparison of ZnMn2O4 microparticle synthesized by sol-gel method. It is found that the microemulsion can effectively control particle size and morphology of the precursor and thus porous ZnMn2O4 nanospheres consisting of smaller primary nanoparticles can be successfully obtained, which exhibit far better rate capability and cyclic stability than ZnMn2O4 microparticles. The porous ZnMn2O4 nanospheres deliver a reversible capacity of 300 mAh g−1 at 6000 mA g−1 and yield a capacity retention of 91% after 120 cycles at 200 mA g−1, compared to the 20 mAh g−1 and 0% of ZnMn2O4 microparticles, respectively. The space in the porous structure of ZnMn2O4 nanospheres buffers the mechanical strain induced by the volume change during cycling, which causes destruction of ZnMn2O4 microparticle, resulting in the excellent cyclic stability. Moreover, the primary nanoparticles in ZnMn2O4 nanospheres reduce the path of lithium ion transportation and increase reaction sites for lithium intercalation/deintercalation, leading to the better rate capability of porous ZnMn2O4 nanospheres than ZnMn2O4 microparticles.

•Self-discharge of charged layered lithium-rich oxide cathode is understood.•Trimethyl borate (TMB) is used as an electrolyte additive to suppress this self-discharge.•Suppression mechanism involves a cathode film derived from the preferential oxidation of TMB.Self-discharge behavior of layered lithium-rich oxide as cathode of lithium ion battery in a carbonated-based electrolyte is understood, and a simple boron-containing compound, trimethyl borate (TMB), is used as an electrolyte additive to suppress this self-discharge. It is found that layered lithium-rich oxide charged under 4.8 V in additive-free electrolyte suffers severe self-discharge and TMB is an effective electrolyte additive for self-discharge suppression. Physical characterizations from XRD, SEM, TEM, XPS and ICP-MS demonstrate that the crystal structure of the layered lithium-rich oxide collapses due to the chemical interaction between the charged oxide and electrolyte. When TMB is applied, the structural integrity of the oxide is maintained due to the protective cathode film generated from the preferential oxidation of TMB.

•Cyclability of layered lithium-rich oxide/graphite cell depends on cathode performance.•HF formed from electrolyte decomposition causes the corrosion of aluminum current collector.•TMSPi is effective for improving cyclability of layered lithium-rich oxide/graphite cell.•Cathode interphase formed from TMSPi suppresses the electrolyte decomposition.We report a failure mechanism of layered lithium-rich oxide/graphite cell and a solution to this failure. Charge/discharge tests demonstrate that Li1.2Mn0.54Ni0.13Co0.13O2/graphite full cell fails when it is performed with cycling and this issue can be solved effectively by using an electrolyte additive, tris (trimethylsilyl) phosphite (TMSPi). Further cycling tests on Li/Li1.2Mn0.54Ni0.13Co0.13O2 and Li/graphite half-cells and physical characterizations on the cycled cathode indicate that this failure involves the increased HF concentration and the subsequent corrosion for aluminum current collector of cathode due to the electrolyte decomposition during cycling. TMSPi contributes to the formation of a protective interphase on cathode due to its preferential oxidation compared with the base electrolyte, which suppresses the electrolyte decomposition and the HF formation, preventing aluminum current collector from corrosion.

•EGBE is investigated as an additive for lithium-rich layered cathode (4.8 V).•Cycling performance of Li/Li1.2Mn0.54Ni0.13Co0.13O2 is enhanced with EGBE added.•The surface layer derived from EGBE on the cathode is more stable.•Dissolution of Mn, Co, and Ni can be reduced with added EGBE upon cycling at 4.8 V.Ethylene glycol bis (propionitrile) ether (EGBE) is used as an electrolyte additive to improve the cycling stability and rate capability of Li/Li1.2Mn0.54Ni0.13Co0.13O2 cells at high operating voltage (4.8 V). After 150 cycles, cells with 1.0 wt% of EGBE containing electrolyte have remarkable cycling performance, 89.0% capacity retention; while the cells with baseline electrolyte only remain 67.4% capacity retention. Linear sweep voltammetry (LSV) and computation results demonstrate that EGBE preferably oxidizes on the cathode surface compared to the LiPF6/carbonate electrolyte. In order to further understand the effects of EGBE on Li1.2Mn0.54Ni0.13Co0.13O2 cathode upon cycling at high voltage, electrochemical behaviors and ex-situ surface analysis of Li1.2Mn0.54Ni0.13Co0.13O2 are investigated via electrochemical impedance spectroscopy (EIS), scanning electron spectroscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and inductive coupled plasma spectroscopy (ICP-MS). The improved cycling performance can be attributed to more stable and robust surface layer yield via incorporation of EGBE, which mitigates the oxidation of electrolyte on the cathode electrode, and also inhibits the dissolution of bulk transition metal ions as well upon cycling at high voltage.

•TEB is an effective electrolyte additive for high voltage LNCM.•The film generated by TEB is thin, uniform and low interfacial resistance.•TEB improves the cyclic stability of LNCM at room and elevated temperature.Triethylborate (TEB) is used as an electrolyte additive to improve the electrochemical performances of LiNi1/3Co1/3Mn1/3O2 (LNCM) upon cycling at 4.5 V vs. Li/Li+. Charge/discharge tests demonstrate that the cyclic stability of LNCM at room and elevated temperature can be improved effectively by TEB. With addition of 10 wt. % TEB into STD electrolyte (1.0 M LiPF6/EC:EMC:DEC), LNCM achieves a capacity retention of 99.8% after 150 cycles and 94.7% after 120 cycles at room and elevated temperature, respectively, comparing to that of 68.9% and 68.8% of STD electrolyte. In addition, 10 wt. % TEB also improves the rate capability of LNCM at room temperature. Physical and electrochemical characterizations from XRD, SEM, TEM, XPS, ICP-MS, LSV, CA, and EIS reveal that the preferential oxidative reaction of TEB generates a thin, uniform and low interfacial resistance film on the LNCM surface. This film not only suppresses the subsequent decomposition of STD electrolyte, but also prevents the dissolution of transition metal ions from LNCM, resulting in improved cyclic stability and rate capability of LNCM.

•Surface oxygen-rich titanium prepared by heat treatment is evaluated as anode of MFC.•Surface oxygen enhances biocompatibility of titanium.•The titanium anode exhibits enhanced electrocatalytic activity toward electron transfer.•MFC delivers improved power output compared with the untreated titanium.We report a novel anode, surface oxygen-rich titanium, for high performance microbial fuel cell. Differently from conventional anodes that are usually composed of electrocatalysts composites and thus exhibit poor dimensional stability, our titanium anode is stable dimensionally and easily available by a simple heat treatment. The surface properties of the resulting anode are characterized with SEM, XPS and XRD, and its electrochemical performances are evaluated in Escherichia coli-based microbial fuel cell. It is found that after heat treatment, titanium contains more surface oxygen atoms and thus delivers higher power output as anode of the microbial fuel cell. Compared with pristine titanium, surface oxygen-rich titanium exhibits better biocompatibility and electrocatalytic activity for the electron transfer between bacteria and anode.

•A novel composite, Fe2O3@C, was synthesized via template-free hydrothermal method.•Fe2O3@C has a configuration consisting of Fe2O3 nanoparticles coated with carbon.•Fe2O3@C exhibits excellent rate capability and cyclic stability.A novel composite of Fe2O3 and carbon (Fe2O3@C) was synthesized hydrothermally without using any template and evaluated as anode of high energy density lithium ion battery. Physical characterizations, from XRD, FESEM, TEM, HRTEM, TGA, XPS, and Raman spectroscopy, demonstrate that the resulting Fe2O3@C takes a morphology of porous rods, which is composed of 100 nm Fe2O3 particles that are coated uniformly with a layer of amorphous carbon. Charge/discharge tests indicate that the resulting Fe2O3@C delivers a reversible discharge capacity of 907 mAh g−1 at 100 mA g−1 and 420 mAh g−1 at 5000 mA g−1, and maintains a discharge capacity of 639 mAh g−1 after 300 cycles at 500 mA g−1. These performances can be attributed to the unique configuration of the Fe2O3@C rods. The nanoparticles in the rods shorten the path of lithium ion diffusion and increase the reaction sites for lithium insertion/extraction, the pores in the rods provide space to accommodate the volume change yielded during charge/discharge process and the carbon coating preserves the structural integrity of Fe2O3.

⿢Li-Rich@AlF3@Graphene was developed as cathode of lithium ion battery.⿢Coating of 2 nm AlF3 does not cause capacity loss but is beneficial to rate capability.⿢Concurrent AlF3 coating and graphene wrapping significantly improve Li-Rich performance.A novel composite of layered lithium-rich oxide with AlF3 and graphene, Li-Rich@AlF3@Graphene, is synthesized as high performance cathode of lithium ion battery in terms of rate capability and cyclic stability. Physical characterizations from X-ray diffraction, scanning electron microscope and transmission electron microscope, demonstrate that the layered lithium-rich oxide in Li-Rich@AlF3@Graphene is composed of uniform nanoparticles of 100 nm, which are coated with a layer of 2 nm AlF3 and wrapped with graphene sheets. Charge/discharge tests indicate that the naked lithium-rich oxide exhibits poor cyclic stability and rate capability as cathode of lithium ion battery, which can be improved to some extent by the only contribution of AlF3 but significantly by the concurrent contribution of AlF3 and graphene.

•MnO/rGO nanocomposite is synthesized and evaluated as anode of lithium ion battery.•The nanocomposite consists of MnO nanoparticles embedded in rGO network.•The nanocompostie exhibits high capacity and good rate and cycle performance.In this paper, we propose a novel fabrication for manganese monoxide and reduced graphene oxide nanocomposite (MnO/rGO), in which microemulsion is introduced to form a 3D architecture consisting of MnO nanoparticles embedded in reduced graphene oxide network. Physical characterizations from SEM, TEM, HRTEM, XPS, Raman, and XRD, indicate that MnO particles of about 230 nm are formed and uniformly embedded in rGO. Charge and discharge tests demonstrate that the resulting MnO/rGO exhibits excellent performances as anode of lithium ion battery, delivering a reversible capacity of as high as 776 mAh g−1 at 1000 mA g−1 after 155 cycles and rate capacity of 306 mAh g−1 at 6000 mA g−1 when it is evaluated in a half cell with lithium as the counter electrode.MnO nanoparticles embedded in 3D graphene network possessing a high specific capacity and exhibiting excellent rate capability.

•Addition of 1% DMAc improves the cyclic performances of LLO at room and elevated temperature.•DMAc oxidizes previously to the STD electrolyte and generates a protective film on the LLO surface.•The protective film is thin and uniform.In this work, dimethylacetamide (DMAc) was investigated as an electrolyte film-forming additive to improve the cyclic stability of high voltage Lithium-rich layered nickel manganese cobalt oxide (LLO) cathode at room (25 °C) and elevated (55 °C) temperature. At 0.5C rate, addition of 1% DMAc slightly decreases the initial discharge capacity of LLO from 187 to 179 mAh g−1 at room temperature and 255 to 246 mAh g−1 at elevated temperature, while significantly improves the capacity retention of LLO from 65.8% to 80.2% after 200 cycles at room temperature and from 21.1% to 66.7% after 150 cycles at elevated temperature. The mechanism of DMAc improving the cyclic stability of LLO was investigated via theoretical calculation and experimental characterizations, which demonstrated that DMAc oxidized preferential to the STD (1.0 M LiPF6 in a mixed solvent of ethylene carbonate/ethyl methyl carbonate/diethyl carbonate) electrolyte, generating a thin and uniform film on the LLO surface. This film effectively suppresses the subsequent decomposition of STD electrolyte and further degradation of spinel phase converted from the layered structure of LLO, resulting in improved cyclic stability of LLO at room and elevated temperature.Addition of 1% DMAc significantly improves the cyclic stability of LLO at high voltage, especially at elevated temperature (55 °C).

•TMSP is effective for self-discharge suppression of the charged NCM under 4.5 V.•TMSP oxidizes preferentially forming protective cathode interface film on NCM.•The film suppresses electrolyte decomposition and prevents NCM destruction.Application of layered nickel cobalt manganese oxide as cathode under higher potential than conventional 4.2 V yields a significant improvement in energy density of lithium ion battery. However, the cathode fully charged under high potential suffers serious self-discharge, in which the interaction between the cathode and electrolyte proceeds without potential limitation. In this work, we use tris(trimethylsilyl)phosphate (TMSP) as an electrolyte additive to solve this problem. A representative layered nickel cobalt manganese oxide, LiNi1/3Co1/3Mn1/3O2, is considered. The effect of TMSP on self-discharge behavior of LiNi1/3Co1/3Mn1/3O2 is evaluated by physical and electrochemical methods. It is found that the self-discharge of charged LiNi1/3Co1/3Mn1/3O2 can be suppressed significantly by using TMSP. TMSP is oxidized preferentially in comparison with the standard electrolyte during initial charging process forming a protective cathode interface film, which avoids the interaction between cathode and electrolyte at any potential and thus prevents electrolyte decomposition and protects LiNi1/3Co1/3Mn1/3O2 from structure destruction.

•3THP is used as an electrolyte additive for high potential LiNi0.5Mn1.5O4 cathode.•Cyclic stability of LiNi0.5Mn1.5O4 is significantly improved by applying 3THP.•3THP is oxidized at the potential before lithium extraction forming a protective cathode film.Terthiophene (3THP) is evaluated as an electrolyte additive for improving cyclic stability of lithium nickel manganese oxide (LiNi0.5Mn1.5O4) cathode for high energy density lithium-ion batteries. Charge/discharge tests demonstrate that 3THP is effective for improving the cyclic stability of LiNi0.5Mn1.5O4. With applying only 0.25% 3THP in a standard (1 M LiPF6 in EC and DMC, 1/2 in volume) electrolyte, the capacity retention of Li/LiNi0.5Mn1.5O4 cell after 350 cycles at 1C (1C = 147 mA g−1) under 4.9 V was improved from 50% to 91%, which is among the best that have been reported in literatures although the content of 3THP is far lower than those achieved by applying other additives. The physical characterizations from scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, indicate that a thin cathode film has been formed on LiNi0.5Mn1.5O4 particles, which suppresses the decomposition of electrolyte and protects LiNi0.5Mn1.5O4 from structural destruction.

Boron-containing electrolyte additives have been successfully used to improve the cyclability for Li-rich layered oxide, a hopeful cathode of high energy density lithium ion battery, but available mechanisms on their contribution are diversified. In this paper, we provide evidence to confirm the mechanism that Li-rich layered oxide is protected by a solid electrolyte interface (SEI) layer derived from boron-containing electrolyte additives. Triethyl borate (TEB), a simple boron-containing molecule, is selected as the electrolyte additive, and a representative Li-rich layered oxide, Li[Li0.2Mn0.54Ni0.13Co0.13]O2, is synthesized for understanding the interfacial properties between the oxide and the electrolyte through physical and electrochemical characterizations. Cyclability tests display that the as-prepared oxide exhibits a fast capacity decrease in the standard electrolyte, 1.0 M LiPF6, in a mixed carbonate solvent of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and ethylene carbonate (EC) (EMC/DMC/EC = 5/2/3, in weight), with only 30% capacity retention after 150 cycles at 0.5 C (1 C = 250 mAh g–1), which can be improved to 79% when 3% TEB is introduced. Physical characterizations demonstrate that the as-prepared oxide suffers a severe structural destruction accompanied by thick deposits from electrolyte decomposition products, but the crystal structure of the oxide is well protected by a uniform solid electrolyte interface (SEI) layer formed from the preferential oxidation of TEB.

A new copolymer, poly(methyl methacrylate-co-butyl acrylate) (P(MMA-co-BA)), was synthesized by emulsion polymerization with different mass ratio of methyl methacrylate (MMA) and butyl acrylate (BA). The membranes were prepared by phase inversion and corresponding gel polymer electrolytes (GPEs) were obtained by immersing the membrane into a liquid electrolyte. In this design, the hard monomer MMA provided the copolymer with good electrolyte uptake, while the soft monomer BA provided the GPE with strong adhesion between the anode and cathode of lithium ion battery. The properties of the resulting product were investigated by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectra, scanning electron spectroscopy, linear sweep voltammetry, thermogravimetric analysis, cyclic voltammetry, electrochemical impedance spectroscopy and charge/discharge test. The results show that the obtained GPE based on P(MMA-co-BA) with the mass ratios of MMA and BA = 6:1 exhibits good conductivity (as high as 1.2 × 10−3 S cm−1) at room temperature and high electrochemical stability (up to 4.9 V vs. Li/Li+). With the application of the polyethylene (PE)-supported GPE in Li/Li(Li0.13Ni0.30Mn0.57)O2 battery, the battery presents good cyclic stability (maintaining 95.4 % of its initial discharge capacity after 50 cycles) at room temperature.

We report a novel composite, sulfur (S) encapsulated in porous carbon nanospheres (PCNS) and coated with conductive polyaniline (PANI) (PCNS-S@PANI), as cathode of lithium–sulfur battery. PCNS is prepared by convenient and controllable hydrothermal synthetic route and loaded with S via chemical deposition and then coated with conductive polyaniline via in situ polymerization under the control of ascorbic acid. The physical and electrochemical performances of the resulting PCNS-S@PANI are investigated by scanning electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption–desorption isotherms, thermogravimetric analysis, electronic conductivity measurement, galvanostatic charge–discharge test, and electrochemical impedance spectroscopy. It is found that PCNS-S@PANI exhibits excellent charge–discharge performances as cathode of lithium–sulfur battery: delivering a discharge capacity of 881 mAh g−1 at 0.2 C (1 C = 1672 mA g−1) with a capacity retention of 72 % after 100 cycles and a rate capacity of 324 mAh g−1 at 2 C. These natures can be attributed to the co-contribution of PCNS and conductive PANI to the improvement in electronic conductivity and chemical stability of sulfur cathode.

A novel composite, porous cubic Mn2O3@TiO2, was fabricated via a simple and cost-effective approach and characterized in terms of structure and performance as an anode for lithium ion batteries. The porous Mn2O3 cubes were developed by calcining cubic MnCO3 particles without using any template and then coated with TiO2 from heat decomposition of tetrabutyl titanate. The characterization from FESEM, TEM, HRTEM, XPS, BET, and XRD indicates that the as-fabricated Mn2O3@TiO2 takes a hierarchically porous cubic morphology with an edge of ∼340 nm and a core–shell structure with porous cubic Mn2O3 as the core, which consists of nanoparticles of ∼30 nm, and a layer of porous single-crystalline spinel TiO2 as the shell, which consists of smaller nanoparticles of ∼5 nm. The charge–discharge tests demonstrate that this unique configuration endows the as-fabricated Mn2O3@TiO2 with superior charge–discharge performance, to be specific, a rate capacity of 263 mA h g−1 at 6000 mA g−1 compared to the 9.7 mA h g−1 of Mn2O3, and a cyclic capacity of 936 mA h g−1 after 100 cycles at 200 mA g−1 compared to the 443 mA h g−1 of Mn2O3. The nanosized particles of Mn2O3 and TiO2 and the hierarchically porous structure among them provide paths for lithium-ion diffusion and sites for lithium-ion intercalation/deintercalation, while the chemically and mechanically stable TiO2 ensures the structural stability of Mn2O3 cubes, yielding excellent rate capability and cyclic stability of the as-fabricated Mn2O3@TiO2 as an anode for lithium ion batteries.

We report a composite (CG-S@PANI), sulfur (S) loaded in curved graphene (CG) and coated with conductive polyaniline (PANI), as a cathode for lithium–sulfur batteries. CG is prepared by splitting multi-wall carbon nanotubes and loaded with S via chemical deposition and then coated with polyaniline via in situ polymerization under the control of ascorbic acid. The physical and electrochemical performances of the resulting CG-S@PANI are investigated by nitrogen adsorption–desorption isotherms, X-ray powder diffraction, thermogravimetric analysis, transmission electron microscopy, electrochemical impedance spectroscopy, charge–discharge tests, and electronic conductivity measurements. CG-S@PANI as a cathode for lithium–sulfur batteries delivers an initial discharge capacity of 851 mA h g−1 (616 mA h g−1 on the basis of the cathode mass) at 0.2 C with a capacity retention of over 90% after 100 cycles. This nature is attributed to the co-contribution of CG and conductive PANI to the concurrent improvement in electronic conductivity and chemical stability of the sulfur cathode.

In this study, polyvinyl alcohol (PVA) is proposed as a new binder to improve the power output of a microbial fuel cell. The physical and chemical properties of PVA are characterized with Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), contact angle testing, density functional theory calculations, and scanning electron microscopy (SEM). The electrochemical performance of an anode using carbon nanotubes as an electrocatalyst and PVA as a binder are evaluated in an Escherichia coli based fuel cell using chronoamperometry, electrochemical impedance spectroscopy (EIS), and polarization curve measurements, and a comparison is made with the conventional binder, polytetrafluoroethylene (PTFE). It is found that PVA is more hydrophilic and has stronger interactions with the bacterial membrane than PTFE. Accordingly, the anode with PVA as a binder facilitates the formation of biofilms and thus exhibits improved electron transfer kinetics between bacteria and the anode of the microbial fuel cell compared to the anode using PTFE. The MFC using PVA produces the largest maximum output power, 1.631 W m−2, which is 97.9% greater than the largest one produced by the MFC using PTFE (0.824 W m−2).

•Charged LiNi1/3Co1/3Mn1/3O2 cathode to 4.5 V suffers serious self-discharge with a potential drop up to 1.0 V.•The mechanism involves the interaction between charged LiNi1/3Co1/3Mn1/3O2 and electrolyte without any limitation.•Self-discharge leads to the formation of over-lithiated compound combined with electrolyte decomposition products.The self-discharge mechanism of LiNi1/3Co1/3Mn1/3O2 cathode for lithium ion battery at high potential (4.5 V) has been understood through physical and electrochemical characterizations including charge/discharge test, electrochemical impedance spectroscopy (EIS), inductively coupled plasma atomic emission spectrometer (ICP-AES), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). It is found that the charged LiNi1/3Co1/3Mn1/3O2 cathode to 4.5 V suffers seriously self-discharge. After storage for 8 days, the potential of the cathode charged to 4.2 V remains stable, while that of the charged cathode to 4.5 V decreases from 4.5 to 1.0 V, The characterizations, from SEM, TEM, ICP-AES, and XRD, demonstrate that this self-discharge results from the interaction between charged LiNi1/3Co1/3Mn1/3O2 and electrolyte, which causes the dissolution of transition metals from LiNi1/3Co1/3Mn1/3O2 and the successive decomposition of the electrolyte.

•Cyclability of LiMn2O4 under elevated temperature can be improved significantly by DMPP.•DMPP can be easily oxidized on LiMn2O4 at the potential before lithium extraction.•Cathode interphase is formed from DMPP without incorporation of electrolyte.•Crystal destruction of LiMn2O4 is prevented and electrolyte decomposition is suppressed.Spinel lithium manganese oxide, LiMn2O4, is a promising cathode for lithium ion battery in large-scale applications, because it possesses many advantages compared with currently used layered lithium cobalt oxide (LiCoO2) and olivine phosphate (LiFePO4), including naturally abundant resource, environmental friendliness and high and long work potential plateau. Its poor cyclability under high temperature, however, limits its application. In this work, we report a significant cyclability improvement of LiMn2O4 under elevated temperature by using dimethyl phenylphonite (DMPP) as an electrolyte additive. Charge/discharge tests demonstrate that the application of 0.5 wt.% DMPP yields a capacity retention improvement from 16% to 82% for LiMn2O4 after 200 cycles under 55  °C at 1 C (1C = 148 mAh g−1) between 3 and 4.5 V. Electrochemical and physical characterizations indicate that DMPP is electrochemically oxidized at the potential lower than that for lithium extraction, forming a protective cathode interphase on LiMn2O4, which suppresses the electrolyte decomposition and prevents LiMn2O4 from crystal destruction.

•Surface natures of five commercial carbon materials were understood.•Carbon with large specific surface area leads to low coulombic efficiency.•Carbon with layered structure leads to low charge/discharge capacity of cathode.•Negative effects become more significant as high voltage cathode material is used.The surface natures of five carbon materials, acetylene black, Super P, ECP600JD, KS-6 and CNTs, are compared in terms of morphology, specific surface area and activity towards electrolyte decomposition and anion insertion, and their contributions as conductive additives to cathode performance of lithium ion batteries are understood. With the characterizations from scanning electron microscopy, Brunauer–Emmett–Teller analysis and cyclic voltammetry, it's demonstrated that: (1) the morphology is granular for acetylene black, Super P and ECP600JD, flake-like for KS-6 and wire-like for CNTs; (2) ECP600JD exhibits the largest specific surface area but KS-6 has the smallest one; (3) the activity is the same for all the samples towards the electrolyte decomposition but different from each other towards anion insertion. Charge/discharge tests of LiMn2O4 and LiNi0.5Mn1.5O4 cathodes indicate that the surface natures of carbon materials play an important role in charge/discharge performance of cathodes for lithium ion batteries. ECP600JD with smallest particle size provides the largest site for electrolyte decomposition leading to the lowest coulombic efficiency, while KS-6 with a layered structure exhibits the highest activity towards anion insertion leading to the lowest charge and discharge capacity of cathode materials. These negative effects become more significant when high voltage cathode materials are used.

•TMSB can improve the cyclic stability of layered lithium-rich oxides significantly.•TMSB oxidizes preferentially to carbonate electrolyte and forms a protective film on the oxides.•Interfacial stability of oxide/electrolyte is improved.•Electrolyte decomposition and oxide structure destruction are inhibited effectively.Tris(trimethylsilyl)borate (TMSB) is used as an electrolyte additive for high voltage lithium-rich oxide cathode of lithium ion battery. The interfacial natures of Li[Li0.2Mn0.54Ni0.13Co0.13]O2/carbonate-based electrolyte are investigated with a combination of electrochemical measurements and physical characterizations. Charge/discharge tests show that the cyclic performance of Li[Li0.2Mn0.54Ni0.13Co0.13]O2 in a mixed carbonate electrolyte is significantly improved by using TMSB. After 200 cycles between 2 V and 4.8 V (vs. Li/Li+) at 0.5 C rate, the capacity retention of Li[Li0.2Mn0.54Ni0.13Co0.13]O2 is only 19% in the blank electrolyte, while it is improved to 74% when 0.5% TMSB is applied. The results from physical characterizations demonstrate that this excellent cyclic performance is attributed to the improved interfacial stability of Li[Li0.2Mn0.54Ni0.13Co0.13]O2/electrolyte due to the thin and protective film generated by TMSB.

•PTS is used as a novel electrolyte additive for high voltage lithium ion battery.•Addition of 0.5% PTS significantly improves the cyclic stability of LiNi0.5Mn1.5O4.•PTS is oxidized preferably to carbonate solvents forming a SEI film.•The film improves the interfacial stability of LiNi0.5Mn1.5O4/electrolyte.In this work, we propose a novel electrolyte additive phenyl trifluoromethyl sulfide (PTS) to improve the interfacial stability of high voltage lithium nickel manganese oxide (LiMn1.5Ni0.5O4) cathode/electrolyte. At 1C rate, addition of 0.5% PTS improves the capacity retention of LiNi0.5Mn1.5O4 from 65% to 84% after 450 cycles at room temperature, and from 64% to 95% after 100 cycles at evaluate temperature. Density functional theory calculation and experimental characterization demonstrate that PTS oxidizes preferentially to the carbonate base electrolyte, generating a SEI film, which effectively suppresses the continuous decomposition of carbonate base electrolyte and the structural destruction of LiMn1.5Ni0.5O4.Addition of 0.5% PTS significantly improves the cyclic stability of LiNi0.5Mn1.5O4 at room and elevated temperature.

•Composite of MWCNTs-S@PANIwas developed as cathode of Li/S battery.•MWCNTs-S was prepared by direct chemical deposition of S on MWCNTs.•PANI was coated on S via in situ polymerization under control of ascorbic acid.•The composite exhibits excellent cyclic stability and rate capability.We report a novel composite, sulfur supported by multi-walled carbon nanotubes and coated with polyaniline (denoted as MWCNTs-S@PANI), as cathode of lithium-sulfur battery. MWCNTs-S is prepared by loading sulfur on MWCNTs via chemical deposition and coated with polyaniline via in situ polymerization under the control of ascorbic acid. The physical and electrochemical performances of the resulting MWCNTs-S@PANI are investigated by nitrogen adsorption-desorption isotherms, X-ray powder diffraction, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, electrochemical impedance spectroscopy, and charge/discharge test. It is found that MWCNTs-S@PANI exhibits good cyclic stability and rate capability compared to MWCNTs-S as cathode of lithium-sulfur battery.

•One-step co-crystallization of oxalates was developed to synthesize layered lithium-rich oxide.•The oxalates provide the product with nanorod morphology and hierarchically porous structure.•The product exhibits improved rate capability and cyclic stability.A layered lithium-rich oxide, Li[Li0.19Mn0.32Co0.49]O2, is synthesized by introducing manganese and cobalt via oxalates co-crystallization in reverse micellar microemulsion. The physical and electrochemical performances of the as-synthesized oxide are evaluated as cathode of lithium ion battery. The physical characterizations, from X-ray diffraction, scanning electron microscope and transmission electron microscope, indicate that the as-synthesized oxide takes a nanorod morphology of up to 1 μm in length and 200 nm in diameter, which is composed of about 20 nm subunit nanoparticles, and possesses a hierarchical pore structure. Electrochemical measurements demonstrate that the as-synthesized oxide exhibits improved charge/discharge performances: less polarization, larger discharge capacity, higher rate capability, and better cyclic stability, compared to the sample synthesized by introducing the transition metals in solid-state reaction.

•4-TB is an effective electrolyte additive for improving the cyclic stability of LiCoO2 under 4.5 V.•4-TB combines with Co(IV) and is oxidized preferentially forming CEI film on LiCoO2.•CEI protects LiCoO2 from structural destruction and suppresses electrolyte decomposition.The cyclic stability of LiCoO2 as cathode of lithium ion battery under 4.5 V is improved by using 4-(trifluoromethyl) benzonitrile (4-TB) as an electrolyte additive. In a standard (STD) electrolyte (1.0 mol/L LiPF6 in EC/EMC/DMC, 1/1/1 by volume) containing 0.5 wt.% 4-TB, LiCoO2 exhibits an improved cyclic stability when the end-off charge potential is increased to 4.5 V. The characterizations, from XRD, ICP, SEM, FTIR, and XPS, demonstrate that a cathode electrolyte interphase (CEI) film is formed on LiCoO2 from 4-TB, which suppresses the successive decomposition of STD electrolyte and prevents LiCoO2 from crystal destruction. Theoretical calculations confirm that 4-TB is adsorbed and oxidized on LiCoO2 preferentially to the carbonates in electrolyte, forming the protective CEI film.

Trimethyl borate (TB) is used as an electrolyte additive to improve cyclic stability and rate capability of a layered cathode, LiNi1/3Co1/3Mn1/3O2 (LNCM), under 4.5 V (vs. Li/Li+). Charge/discharge tests demonstrate that the cyclic stability and rate capability of LNCM can be improved significantly by adding TB into a standard (STD) electrolyte, 1.0 mol L−1 LiPF6 in ethylene carbonate/ethyl methyl carbonate/diethyl carbonate (3/5/2, in weight). After 200 cycles at 0.5C between 3.0 and 4.5 V, LNCM exhibits a capacity retention of 89% in 10% TB-containing electrolyte, but only 48% in STD electrolyte. Unlike other additives, which usually decrease the rate capability when they are used for the cyclic stability improvement of LNCM, the discharge capacity of LNCM at 6C is enhanced from 78 mAh g−1 in STD electrolyte to 102 mAh g−1 in 10% TB-containing electrolyte. Physical and electrochemical characterizations demonstrate that these improvements result from the preferential oxidation of TB compared to the STD electrolyte and the formation of a stable and low impedance film on LNCM cathode surface, which suppresses concurrently the decomposition of electrolyte and the dissolution of transition metal ions from LNCM.

In this article, we report a novel gel polymer electrolyte (GPE) for lithium ion batteries, which is prepared using poly(methyl methacrylate-acrylonitrile-ethyl acrylate) (P(MMA-AN-EA)) as a polymer matrix and doping with nano-SiO2 and nano-Al2O3 simultaneously. The influences of the ratio of the two nanoparticles on the pore structure, electrolyte uptake and thermal stability of the resulting membrane, and the ionic conductivity and electrochemical stability of the corresponding GPE are investigated by scanning electron microscopy, mechanical strength, thermogravimetry, electrochemical impedance spectroscopy, linear sweep voltammetry and cyclic voltammetry. The performance of the developed GPE is evaluated in the Li/LiNi0.5Mn1.5O4 half cell by a charge–discharge test for its application in lithium ion batteries. It is found that there exists a synergistic effect between nano-SiO2 and nano-Al2O3. The performances of the resulting membrane and the corresponding GPE are effectively improved by using nano-SiO2 and nano-Al2O3 simultaneously rather than individually. Co-doping 5 wt% nano-SiO2 and 5 wt% nano-Al2O3 provides the membrane with a higher thermal decomposition temperature of 325 °C, and a better electrolyte uptake of 198.1%, the corresponding GPE with an increased ionic conductivity of 2.2 × 10−3 S cm−1 at room temperature and an enhanced oxidative stability up to 5.5 V (vs. Li/Li+), and the LiNi0.5Mn1.5O4 cathode with an improved rate capability of 104.2 mA h g−1 at 2C and an improved capacity retention of 94.8% after 100 cycles. These improved performances result from combining the advantages of both nano-SiO2 and nano-Al2O3, in which the former contributes to the improved ionic conductivity caused by a stronger Lewis-acid property, while the latter to the better thermal and structural stabilities by its stiffness characteristic.

•Porous carbon (DPC) with a defined pore size was prepared to improve performance of MFC.•Suitable pore size of DPC for accommodating bacteria facilitates the formation of biofilm.•MFC based on DPC anode material delivers a superior power output.This paper reported a novel anode material, porous carbon with a defined pore size (DPC) matching bacteria, for microbial fuel cell (MFC). The DPC was prepared by using silica spheres as templates and sucrose as carbon precursor. The structure and morphology of the as-prepared DPC were characterized with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and its performance as anode of MFC based on Escherichia coli (E. coli) was evaluated with chronoamperometry, cyclic voltammetry (CV) and polarization curve measurement. The result from SEM demonstrates that pores in the as-prepared DPC are well defined with an average diameter of 400 nm, which is a little larger than that of E. coli, and the polarization curve measurement shows that the as-prepared DPC exhibits superior performance as anode material loaded on carbon felt, delivering a power output of 1606 mW m−2, compared to the 402 mW m−2 of naked carbon felt anode, in the solution containing 2 g/L glucose. The excellent performance of the as-prepared DPC is attributed to its suitable pore size for accommodating E. coli strain, which facilitates the formation of bacterial biofilm and the electron transfer between bacteria and anode.

A novel gel polymer electrolyte (GPE) based on an electrospun polymer membrane of polyimide (PI) activating with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and further coating with nano-Al2O3 was prepared, and its performance for lithium-sulfur (Li-S) cell was investigated. It is found that the Li-S cell using the new GPE enabled achieving a stable discharge capacity of 820 mAh g−1 after more than 100 cycles. This new GPE system with activating with PVDF-HFP and further coating with nano-Al2O3 was capable of upholding the electrolyte solution and can suppress the dissolution of the intermediate products generated during the discharge process and thus improves the performance of Li-S cell.

A novel carbon-sulfur composite, mesoporous carbon-sulfur, was developed as cathode of lithium/sulfur battery. The mesoporous carbon was prepared with sucrose as carbon precursor and calcium carbonate nanoparticles as pore producer. The sulfur was encapsulated in the mesoporous carbon via a simple chemical deposition strategy and a subsequent low-temperature thermal treatment process. The morphology and structure of the resulting composite were characterized with scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller measurement, and thermogravimetric analysis. Its electrochemical performances as cathode of lithium/sulfur battery were evaluated with cyclic voltammetry and charge-discharge test. The prepared carbon showed a specific surface area of 598 m2 g−1 with a bimodal pore distribution centered at 3.6 and 40 nm. The resulting mesoporous carbon-sulfur delivered an initial capacity of 1,380 mAh g−1 at 0.02 C and maintained  a capacity of 750 mAh g−1 after 100 cycles at 0.1 C.

LiNi0.5Mn1.5O4 is synthesized by a sol–gel method, and its performance as cathode of high-voltage lithium-ion battery is improved by using poly(vinylidene fluoride-co-hexafluoropropene)-based gel polymer electrolyte (GPE). The results obtained from charge/discharge tests demonstrate that the cyclic stability of LiNi0.5Mn1.5O4 is significantly improved by using the GPE, especially at elevated temperature. After 150 cycles, the discharge capacity of LiNi0.5Mn1.5O4 drops sharply from 127 to 60 mAh g−1 when using liquid electrolyte, while remaining a high value when using GPE, from 134 to 124 mAh g−1. The improved performance is attributed to the enhanced stability of the electrolyte when substituting GPE for liquid electrolyte.

In this work, we report a new finding that thiophene can be used as an electrolyte additive to form simultaneously protective cathode film and conductive polymer and thus to improve significantly the cyclic stability and rate capability of LiNi0.5Mn1.5O4 cathode for a high-voltage lithium-ion battery. The contribution of thiophene is evaluated in a Li/LiNi0.5Mn1.5O4 cell, with charge/discharge test, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier-transformed infrared spectra (FTIR), and X-ray photoelectron spectroscopy (XPS). The charge/discharge tests demonstrate that the capacity retention of LiNi0.5Mn1.5O4 with 1-C (1 C = 147 mA g−1) rate is improved from 37.2 to 78.8 % at 55 °C after 100 cycles, and the discharge capacity with 10-C rate is enhanced from 83 to 111 mAh g−1 when adding 0.5 % thiophene into 1 M LiPF6 in ethylene carbonate (EC)/ dimethyl carbonate (DMC) (1/2, v/v) solution. CV shows that thiophene is oxidized at 4.5 V (vs. Li/Li+), forming a protective film on and conductive polymer among LiNi0.5Mn1.5O4 particles, which can be confirmed by EIS, XRD, SEM, TEM, FTIR, and XPS.

With an aim to broaden the understanding of factors influencing oxygen loss, reversible capacity, and cyclic stability of lithium-rich layered oxide cathodes for lithium ion batteries, a series of Fe substituted Li[Li0.2Ni0.13Mn0.54Co0.13]O2 samples, Li[Li0.2Ni0.13-x/2Mn0.54-x/2Co0.13Fex]O2 (x = 0, 0.02, 0.04, and 0.08) and Li[Li0.2Ni0.13Mn0.54Co0.13-yFey]O2 (y = 0, 0.02, 0.04, and 0.06), have been synthesized with a hydroxide co-precipitation method and comparatively studied with X-ray diffraction (XRD), scanning electron microscope (SEM), and charging/discharging measurements. The results indicate that with increasing the Fe substitution for either Co3+ or [Ni0.5Mn0.5]3+, the oxygen loss during the first charge dramatically decreases, leading to the decrease in reversible capacity. Interestingly, the substitution for Co3+ can significantly suppress the voltage decay of the material with extended cycling. For instance, the decayed voltage in 30 cycles is 0.21 V for Li[Li0.2Ni0.13Mn0.54Co0.13]O2, while only 0.11 V for Li[Li0.2Ni0.13Mn0.54Co0.07Fe0.06]O2. The suppression mechanism is discussed.

A new carbon coating method for improving the performance of anode material of lithium ion battery is proposed in this paper. In this method, cetyl trimethyl ammonium bromide (CTAB) is used as dispersant and phenolic resin formed in situ on Li4Ti5O12-TiO2 is used as carbon precursor; thus, uniform coated sample with low carbon content is achieved. Three samples with different carbon contents are prepared, and their carbon content, morphology, structure, and electrochemical performance are investigated by thermogravimetry, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy, and charge-discharge test. It is found that the sample with a carbon content of as low as 2.5 wt.% exhibits superior electrochemical performance. It delivers an initial capacity of 162.4 mAh g−1 with capacity retention of 95 % after 200 cycles at 1 C rate. When cycled at a higher rate of 5 C, the sample delivers a capacity of 148 mAh g−1 with no apparent capacity decaying after 90 cycles. The superior performance of the developed anode can be attributed to the uniform carbon coating.

Carbon-coated LiNi0.5Mn1.5O4 cathode was prepared using phenolic resin as a carbon precursor. The morphology and structure of the prepared samples were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and thermogravimetry, and its performance as cathode of lithium ion battery was investigated by electrochemical impedance spectroscopy and charge-discharge test. The results showed that the carbon coating with phenolic resin as precursor could obviously promote the discharge capacity of LiNi0.5Mn1.5O4 cathode, especially at high rate. At 20 C rate, the discharge capacity is 41 mAh∙g-1 for uncoated LiNi0.5Mn1.5O4, while 108 mAh∙g-1 for carbon-coated LiNi0.5Mn1.5O4. The coated sample also exhibited excellent cyclic performance, remaining 95 % of its initial discharge capacity (131 mAh∙g-1) at 1 C rate after 100 cycles. The interfacial resistance of LiNi0.5Mn1.5O4 with carbon coating was reduced from 90 to 31 Ω.

In this paper, we report a novel structure of Mn2O3, the triple-shelled Mn2O3 hollow nanocube, as the anode material for high-energy lithium-ion batteries, synthesized through a programmed annealing treatment with cubic MnCO3 as precursor. This hierarchical structure is developed through the interaction between the contraction force from the decomposition of MnCO3 and the adhesion force from the formation of Mn2O3. The structure has been confirmed by characterization with XRD, FESEM, TEM, and HRTEM. The charge–discharge tests demonstrate that the resulting Mn2O3 exhibits excellent cycling stability and rate capability when evaluated as an anode material for lithium-ion batteries. It delivers a reversible capacity of 606 mA h g−1 at a current rate of 500 mA g−1 with a capacity retention of 88% and a remaining capacity of 350 mA h g−1 at 2000 mA g−1.

We report a novel synthesis of spinel LiNi0.5Mn1.5O4, in which cubic and porous Mn2O3 nanoparticles, obtained from cubic MnCO3, are used as templates to induce the formation of crystallographic facet- and size-defined spinel. This is done to accomplish excellent cyclic stability of the spinel as a cathode of a high voltage lithium ion battery. The uniformly dispersed pores in the template, whose size can be controlled by limiting the annealing time of MnCO3, facilitate the incorporation of lithium and nickel ions and ensure the formation of spinel with a predominant (111) facet, while the spinel inherits the particle size of the template under controlled temperatures. The characterizations from SEM, TEM and XRD confirm the structure and morphology of the precursors and the resulting product. The charge–discharge test demonstrates the excellent cyclic stability of the resulting products, especially at elevated temperatures: capacity retention of 78.1% after 3000 cycles with 10 C rate at room temperature and that of 83.2% after 500 cycles with 5 C rate at 55 °C.

Porous LiMn2O4 was fabricated with cubic MnCO3 as precursor and characterized in terms of structure and performance as the cathode of a lithium ion battery. The characterizations from SEM, TEM and XRD demonstrate that the fabricated product has a cubic morphology with an average edge of 250 nm, which it inherits from the precursor, and a porous structure architectured with single-crystalline spinel nanoparticles of 50 nm, which imitates the Mn2O3 that results from the thermal decomposition of the precursor. The charge–discharge tests show that the synthesized product exhibits excellent rate capability and cyclic stability: delivering a reversible discharge capacity of 108 mA h g−1 at a 30 C rate and yielding a capacity retention of over 81% at a rate of 10 C after 4000 cycles. The superior performance of the synthesized product is attributed to its special structure: porous secondary cube particles consisting of primary single-crystalline nanoparticles. The nanoparticle reduces the path of Li ion diffusion and increases the reaction sites for lithium insertion/extraction, the pores provide room to buffer the volume changes during charge–discharge and the single crystalline nanoparticle endows the spinel with the best stability.

•4-TB is used as a novel electrolyte additive for high voltage lithium ion battery.•Cyclic stability of LiNi0.5Mn1.5O4 is improved significantly by using 4-TB.•4-TB is oxidized preferably to carbonate solvents forming a low-impedance protective film.•The film suppresses subsequent decompositions of electrolyte and LiNi0.5Mn1.5O4.In this work, 4-(Trifluoromethyl)-benzonitrile (4-TB) is used as a novel electrolyte additive for LiNi0.5Mn1.5O4 cathode of high voltage lithium ion battery. Charge–discharge tests show that the cyclic stability of LiNi0.5Mn1.5O4 is significantly improved by using 0.5 wt.% 4-TB. With using 4-TB, LiNi0.5Mn1.5O4 delivers an initial capacity of 133 mAh g−1 and maintains 121 mAh g−1 after 300 cycles with a capacity retention of 91%, compared to the 75% of that using base electrolyte (1 M LiPF6 in ethylene carbonate(EC)/dimethyl carbonate(DMC)). The results from linear sweep voltammetry, density functional theory calculations, electrochemical impedance spectroscopy, scanning electron microscope, energy dispersive spectroscopy, Fourier transform infrared, and inductively coupled plasma, indicate that 4-TB has lower oxidative stability than EC and DMC, and is preferentially oxidized on LiNi0.5Mn1.5O4 forming a low-impedance protective film, which prevents the subsequent oxidation decomposition of the electrolyte and suppresses the manganese dissolution from LiNi0.5Mn1.5O4.Improved cyclic stability of LiNi0.5Mn1.5O4 by using 0.5 wt.% 4-TB.

•Ultrafine Li4Ti5O12/C composite was prepared by microemulsion-assisted method.•Oleic acid was used as carbon precursor and particle size controller.•Ultrafine Li4Ti5O12 particles are uniformly dispersed in carbon matrix.•The composite exhibits excellent rate performance and cyclic stability.Ultrafine Li4Ti5O12/C composite is synthesized by microemulsion with oleic acid as carbon precursor and particle size controller. The as-prepared sample is characterized with X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), thermogravimetry analysis (TGA) and nitrogen absorption–desorption isotherms, and its performance as anode of lithium ion battery is determined with charge–discharge test and electrochemical impedance spectroscopy (EIS). The characterizations show that the as-prepared sample is composed of ultrafine Li4Ti5O12 particles with average size of 25 nm, which are uniformly dispersed in carbon matrix with a carbon content as low as 2.69 wt%. Charge–discharge test indicates that the as-prepared sample exhibits excellent rate performance and cycling stability. At 10C, the highest discharge capacity reaches 136.3 mAh g−1 and the capacity retention is 96.4% after 100 cycles. The improved performance of the Li4Ti5O12/C composite is attributed to the ultrafine particle size and the uniform composite of Li4Ti5O12 with carbon.

•Utilizes double step search for selecting the parameters c and g for SVR with RBF kernel.•Optimized SVR exhibits generalization ability to samples under different running conditions.•Optimized SVR fits the nonlinear curve of battery capacity with less MSE and error than ANN.State-of-charge (SOC) estimation is one of the most challengeable tasks for battery management system (BMS) in electric vehicles. Since the external factors (voltage, current, temperature, arrangement of the batteries, etc.) are complicated, the formula of SOC is difficult to deduce and the existent SOC estimation methods are not generally suitable for the same vehicle running in different road conditions. In this paper, we propose a new SOC estimation based on an optimized support vector machine for regression (SVR) with double search optimization process. Our developed method is tested by simulation experiments in the ADVISOR, with a comparison of the estimations based on artificial neural network (ANN). It is demonstrated that our method is simpler and more accurate than that based on ANN to deal with the SOC estimation task.

•Composite of MA-g-PVDF with PVDF was developed as binder for LiCoO2 cathode of lithium ion battery.•Composite exhibits lower crystallinity than PVDF and increases electrolyte uptake of cathode.•Application of composite improves significantly rate capability and cyclic stability of battery.In this work, we have developed a novel polymer composite (MPVDF) by embedding maleic anhydride-grated-polyvinylidene fluoride (MA-g-PVDF) into polyvinylidene fluoride (PVDF) as binder of LiCoO2 cathode for lithium ion battery. The cathodes using MPVDF and PVDF as binder have been comparatively investigated with scanning electron microscope (SEM), X-ray diffraction (XRD) and electrochemical measurements. By using MPVDF as the binder for preparing LiCoO2 cathode, the rate capability and cyclic stability of the LiCoO2 cathode in LiCoO2/Artificial graphite battery are improved significantly. Compared to the cathode using PVDF alone, the discharge capacity of the battery increases by 38.5% at 2 C and the capacity retention of the battery is improved from 84.5% to 90.2% after 300 cycles at 0.5 C when the mass ratio of MA-g-PVDF to PVDF in MPVDF binder is 1:4. The improved performance is attributed to the low crystallinity of MPVDF, which allows larger electrolyte uptake. The electrolyte uptake is 43.5% for the LiCoO2 cathode using MPVDF but only 25.3% for the cathode using PVDF alone.

•TMSP is used as an electrolyte additive for LiNi0.5Mn1.5O4 cathode battery at high voltage (4.9 V).•The cyclability of the Li-ion battery at RT and ET can be improved by the use of TMSP.•The rate capability of the Li-ion battery can be improved by the use of TMSP.•Incorporation of TMSP can form a more stable and more conductive surface film on the cathode.In this work, tris (trimethylsilyl) phosphate (TMSP) is used as an electrolyte additive to improve the cycling performance of Li/LiNi0.5Mn1.5O4 cell upon cycling at high voltage, 4.9 V vs. Li/Li+ at room temperature and elevated temperature (55 °C). The effects of TMSP on the cathode interface and the cycling performance of Li/LiNi0.5Mn1.5O4 cell were investigated via the combination of electrochemical methods, including cycling test, cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). It is found that cells with electrolyte containing TMSP have better capacity retention than that of the cells without TMSP upon cycling at high voltage at room temperature and elevated temperature. The functional mechanism of incorporation of TMSP to the electrolyte to improve the cycling performance is conducted with ex-situ analysis approaches, including X-ray diffraction (XRD), scanning electron microscope (SEM), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM) and ICP-MS. The surface analysis results reveal that more stable and more conductive surface layer is formed on the LiNi0.5Mn1.5O4 electrode with TMSP containing electrolyte, which is a leading factor for the enhanced the cycling performance of Li/LiNi0.5Mn1.5O4 cells upon cycling at high voltage at room temperature and elevated temperature.

•Pore-arrayed HxMoO3 was prepared by using polystyrene spheres as templates.•Electrocatalyst with platinum nanoparticles dispersed on pore-arrayed HxMoO3 was developed.•Pore-arrayed HxMoO3 reduces particle size and increases specific surface area of platinum.•Pore-arrayed HxMoO3 improves electrocatalytic activity of platinum toward methanol oxidation.A novel electrocatalyst for methanol oxidation is fabricated by decorating platinum nanoparticles on pore-arrayed hydrogen molybdenum bronze (HxMoO3). In this fabrication, pore-arrayed HxMoO3 is prepared with polystyrene monolayer as a template, and platinum nanoparticles are decorated on the resulting pore-arrayed HxMoO3 by using a current pulse technique. The fabricated electrocatalyst is investigated with a combination of physical characterizations from X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy, and electrochemical measurements including cyclic voltammetry, chronopotentiometry, chronoamperometry, and cell discharge test. It is found that the platinum decorated on pore-arrayed HxMoO3 (Pt/p-HxMoO3) is more uniform, has smaller particle size and exhibits improved electrocatalytic activity and stability for methanol oxidation, compared to that on non-pore-arrayed HxMoO3 (Pt/HxMoO3). The peak current for methanol oxidation in cyclic voltammetry is improved from 4.89 mA cm−2 for Pt/HxMoO3 to 6.41 mA cm−2 for Pt/p-HxMoO3, and the time for abrupt potential change in chronopotentiometry is enhanced from 498 min for Pt/HxMoO3 to 576 min for Pt/p-HxMoO3. The improved performance is attributed to the larger specific surface area of the pore-arrayed HxMoO3, which favors the formation of smaller Pt nanoparticles.

•LiNi0.5Mn1.5O4 nanoparticles are synthesized with synergistic effect of PVP and EG.•The LiNi0.5Mn1.5O4 nanoparticles exhibit excellent rate capability and cyclic stability.•Charging protocol of CC followed by CV step helps understand the excellent performance.LiNi0.5Mn1.5O4 was synthesized by sol–gel using polyvinylpyrrolidone (PVP) as dispersant and ethylene glycol (EG) as size-controlled additive. Crystal structure, particle morphology and electrochemical performance of the resulting product (PVP–LNMO) as cathode of lithium ion battery were investigated with XRD, SEM, CV, EIS, and charge/discharge test, with a comparison of LiNi0.5Mn1.5O4 (LNMO) synthesized under the same conditions but without using PVP and EG. It is found that PVP–LNMO is composed of dispersed LiNi0.5Mn1.5O4 nanoparticles with uniform size, and exhibits far better rate capability and cyclic stability than LNMO. The particles of the latter are in micro size due to the aggregation of smaller primary particles. PVP–LNMO delivers a reversible discharge capacity of 96 mAh g−1 at 20C rate with a capacity retention of 93% at 5C rate after 500 cycles, while only 40 mAh g−1 and 53% for LNMO, respectively. The nanoparticles provide shorter distance for electron and lithium ion transport and larger surface area for electron exchange on the electrode/electrolyte interface, resulting in the far better rate capability of PVP–LNMO than LNMO, while the room among nanoparticles in PVP–LNMO releases the stress of Jahn–Teller distortion that causes destruction of LNMO microparticles, resulting in the excellent cyclic stability.

•Novel α-Fe2O3 nanorods/carbon nanofibres composite is prepared hydrothermally with PVP-assistance.•α-Fe2O3 nanorods are enwrapped with soft and curly carbon nanofibers.•Composite exhibits superior performance in terms of rate capability and cycle stability.•Bondage from the nanofibres improves electronic conductivity and structure stability of α-Fe2O3.A novel Fe2O3/carbon composite is prepared using a facile one-step hydrothermal method. Its structure, morphology and performance as anode of lithium ion battery are investigated with X-ray diffraction, scanning electron microscopy, thermogravimetry, cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. It is found that the as-prepared composite is composed of α-Fe2O3 nanorods of about 75 nm in diameter and 1 μm in length, which are enwrapped with soft and curly carbon nanofibers, and exhibits superior charge/discharge performance compared to bare α-Fe2O3 nanorods, especially at high current rate. The discharge capacity is 1069 mAh g−1 at the first cycle and remains 560 mAh g−1 after 30 cycles at 0.2C for the bare nanorods, but improved to 1278 mAh g−1 and 960 mAh g−1 for the composite. At 12C, the discharge capacity is only 798 mAh g−1 initially and becomes 98 mAh g−1 after 30 cycles for the bare nanorods, while 844 mAh g−1 and 292 mAh g−1 for the composite. The improved performance of the composite is attributed to the bondage from carbon nanofibers, which contributes to the improvement in electronic conductivity and structure stability of α-Fe2O3 nanorods.

•Performance of PA as electrolyte additive of Li-ion battery is improved by F-substituting.•4-FPA is more effective than PA for forming SEI on graphite in PC-based electrolyte.•4-FPA improves cyclic stability of Li-ion battery using PC-based electrolyte.•Incorporation of 4-FPA reduction products into SEI contributes to the improved performance.Phenyl acetate (PA) is more stable and much cheaper than vinylene carbonate (VC), a commercial electrolyte additive for graphite anode of lithium ion battery, but its performance needs to be improved. In this paper, we report a new additive, 4-fluorophenyl acetate (4-FPA), which results from the fluorine-substituting of PA. The properties of the formed solid electrolyte interphase (SEI) by 4-FPA are investigated comparatively with PA by molecular energy level calculation, cyclic voltammetry, charge–discharge test, scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. It is found that the SEI formed by 4-FPA is more protective than PA, resulting in the improved cyclic stability of lithium ion battery: the capacity retention of LiFePO4/graphite cell after 90 cycles is 92% for 4-FPA but only 84% for PA. The fluorine in 4-FPA makes it more reducible than PA and the fluorine-containing reduction products of 4-FPA are incorporated into the SEI, which contributes to the improved performance.

•P(MMA-co-BA)/nano-SiO2/PE based GPE was developed for high voltage lithium ion battery.•P(MMA-co-BA)/nano-SiO2/PE has uniform and interconnected pore structure.•The GPE exhibits improved ionic conductivity and compatibility with electrodes.•5 V battery using the GPE presents excellent cyclic stability.Nano-SiO2 as dopant was used for preparing polyethylene-supported poly(methyl methacrylate-co-butyl acrylate) (P(MMA-co-BA)/PE) based membrane and corresponding gel polymer electrolyte (GPE), which is applied to improve the cyclic stability of high voltage lithium ion battery. P(MMA-co-BA)/nano-SiO2/PE based membranes and corresponding GPEs were characterized with scanning electron spectroscopy, X-ray diffraction, electrochemical impedance spectroscopy, mechanical test, thermogravimetric analysis, linear sweep voltammetry, and charge/discharge test. It is found that the GPE with 5 wt.% nano-SiO2 shows the best performance. Compared to the undoped membrane, the 5 wt.% nano-SiO2 doped membrane has a better pore structure and higher electrolyte uptake, leading to the enhancement in ionic conductivity of the resulting GPE from 1.23 × 10−3 to 2.26 × 10−3 S.cm−1 at room temperature. Furthermore, the thermal stability of the doped membrane is increased from 300 to 320 °C while its decomposition potential of GPE is from 5.0 to 5.6 V (vs. Li/Li+). The cyclic stability of Li/GPE/Li(Li0.13Ni0.30Mn0.57)O2 cell at the high voltage range of 3.5 V ∼ 5.0 V is consequently improved, the capacity retention of the cell using the doped membrane is 92.8% after 50 cycles while only 88.9% for the cell using undoped membrane and 66.9% for the cell using liquid electrolyte.

A novel method, self-directed chemical method, is proposed to synthesize lithium-rich layered oxide Li[Li0.2Ni0.2Mn0.6]O2 as cathode of lithium ion batteries with improved rate capability. In this method, Li2CO3 powder that has low dissolvability in aqueous solution is introduced as precipitating agent to induce the formation of transition-metal carbonate, resulting in the precursor Ni0.25Mn0.75CO3 with a hierarchical structure: secondary particles assembled with interconnected primary particles. This hierarchical structure remains in subsequent product (Li[Li0.2Ni0.2Mn0.6]O2-T). Electrochemical measurements indicates that Li[Li0.2Ni0.2Mn0.6]O2-T delivers a capacity of 222 mAh g−1 at 1st cycle (0.05 C, 1 C = 263 mAh g−1) and holds 207 mAh g−1 at 50th cycle, which is slightly better than the sample from a traditional co-precipitation method (Li[Li0.2Ni0.2Mn0.6]O2-L). More importantly, Li[Li0.2Ni0.2Mn0.6]O2-T is able to stably offer 156 mAh g−1 at 0.5 C, 136 mAh g−1 at 1 C and 108 mAh g−1 at 2 C, much better than Li[Li0.2Ni0.2Mn0.6]O2-L. The improved performance is attributed to the tightly interconnected structure and smaller particle size, which facilitates the diffusion of Li+ ions in the material bulk and reduces the barrier of charge transfer reaction.

•Influence of lithium salts on the anodic stability of sulfolane has been investigated.•Oxidation decomposition mechanisms of LiPF6/Sulfolane electrolyte have been well understood by theoretical and experimental methods.•Decomposition products of the electrolyte can be found on the electrode surface and in the interfacial electrolyte.In this work, we investigated the anodic stability and decomposition mechanism of sulfolane (SL). The anodic stability of SL-based electrolyte with different lithium salts on Pt and LiNi0.5Mn1.5O4 electrodes was found to decrease as follows: LiPF6/SL > LiBF4/SL > LiClO4/SL. The oxidation potential of 1M LiPF6/SL electrolyte on both Pt and electrodes is about 5.0V vs Li/Li+. The presence of PF6- and another SL solvent dramatically alters the decomposition mechanism of SL. Oxidation decomposition of SL-SL cluster is the most favorable reaction in LiPF6/SL electrolyte. The dimer products with S-O-R group were detected by IR spectra on the charged LiNi0.5Mn1.5O4 electrode surface and in the electrolyte near the electrode surface, and were found to increase the interfacial reaction resistance of the LiNi0.5Mn1.5O4 electrode.

•Pore-arrayed HxWO3 was fabricated using PS spheres as template by electrodepostion.•Pt nanoparticles can be stabilized on pore-arrayed HxWO3.•Pt supported by pore-arrayed HxWO3 exhibits excellent activity toward methanol oxidation.Pore-arrayed hydrogen tungsten bronze (p-HxWO3) is fabricated with polystyrene as template by electrodeposition and used as the support of platinum nanoparticles as electrocatalyst (Pt/p-HxWO3) for methanol oxidation. The surface morphology, structure, and compositions of p-HxWO3 and Pt/p-HxWO3 are characterized with scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The activity and stability of Pt/p-HxWO3 toward methanol oxidation are evaluated in 0.5 M H2SO4 + 1.0 M CH3OH solution by cyclic voltammetry (CV), chronoamperometry (CA), and chronopotentiometry (CP), and cell discharge test. The characterizations from SEM, XRD, TEM, and FTIR demonstrate that p-HxWO3 contains uniform pores of about 200 nm and the platinum particles can be uniformly distributed with an average size of 3.01 nm on it. The electrochemical evaluations indicate that Pt/p-HxWO3 exhibits better activity and stability toward methanol oxidation than the platinum supported by non-pore arrayed HxWO3.

The cycling performance of 5 V Li/LiNi0.5Mn1.5O4 cells with 1.0 M LiPF6 EC/DMC (1/2, v/v) with and without TMSB (0.2, 0.5, 1.0 and 2.0 wt.%) has been investigated. After 200 cycles, the cells with 1.0 wt.% TMSB have superior cycling performance with 95.3% capacity retention; while the cells with baseline electrolyte only maintain 84.4% capacity retention. The cells with 1.0 wt.% TMSB containing electrolyte have lower impedance after cycling at high voltage. In addition, the TMSB added cells show superior elevated temperature storage performance, the discharge capacity is 122.1 mAh g−1 and 109.9 mAh g−1 for the cells with and without TMSB after storage at 60 °C for a week at fully charged state, respectively. In order to further understand the effects of TMSB on LiNi0.5Mn1.5O4 cathode upon cycling at high voltage, scanning electron microscopy (SEM), thermal-gravimetric analysis (TGA), transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscope (XPS), Fourier transform infrared spectroscopy (FTIR), and inductively coupled plasma mass spectrometry (ICP-MS) analysis were conducted after the cycling test. The results indicate that the use of TMSB can form a stable and compact film on the surface of the LiNi0.5Mn1.5O4 electrode, which inhibits the continuous decomposition of the electrolyte and reduces the dissolution of Mn and Ni from the bulk cathode material.

•Cyclic stability of LiNi0.5Mn1.5O4 is improved significantly by using PES as additive.•A protective SEI is formed on LiNi0.5Mn1.5O4 due to the preferential oxidation of PES.•The SEI suppresses electrolyte decomposition and structure destruction of LiNi0.5Mn1.5O4.We report a new approach to improve the cyclic stability of lithium nickel manganese oxide (LiNi0.5Mn1.5O4) cathode, in which the cathode/electrolyte interface is modified by using prop-1-ene-1, 3-sultone (PES) as an electrolyte additive. The interfacial properties of LiNi0.5Mn1.5O4 cathode in PES-containing electrolyte have been investigated by scanning electron spectroscopy (SEM), transmission electron microscopy (TEM), thermal gravimetry (TG), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), cyclic voltammometry (CV), chronoamperometry (CA), and constant current charge/discharge test. It is found that the application of PES improves significantly the cyclic stability of LiNi0.5Mn1.5O4. After 400 cycles at 1C rate (1C=147 mA g−1), the capacity retention of LiNi0.5Mn1.5O4 is 90% for the cell using 1.0 wt% PES, while only 49% for the cell without the additive. The characterizations from SEM, TEM, TG, XRD, and XPS confirm that the LiNi0.5Mn1.5O4/electrolyte interface is modified and a protective solid electrolyte interface film is formed on LiNi0.5Mn1.5O4 particles, which prevents LiNi0.5Mn1.5O4 from destruction and suppresses the electrolyte decomposition.

•Cyclic stability of LiNi1/3Co1/3Mn1/3O2 is improved significantly by using TMSPi as additive.•Protective SEI film is formed on LiNi1/3Co1/3Mn1/3O2 due to the preferential oxidation of TMSPi.•SEI film suppresses electrolyte decomposition and LiNi1/3Co1/3Mn1/3O2 destruction.Tris(trimethylsilyl) phosphite (TMSPi) is reported as an effective electrolyte additive for high voltage layered lithium nickel cobalt manganese oxide cathode of lithium ion battery. Charge/discharge tests demonstrate that the cyclic stability and rate capability of LiNi1/3Co1/3Mn1/3O2 can be improved significantly by adding 0.5wt% TMSPi into a standard electrolyte, 1.0 M LiPF6 in ethylene carbonate/dimethyl carbonate (1/2, in volume). The capacity retention of LiNi1/3Co1/3Mn1/3O2 is improved from 75.2% to 91.2% after 100 cycles at 0.5 C rate (1C = 160 mA g−1), while its discharge capacity at 5 C is enhanced from 122.4 mAh g−1 to 134.4 mAh g−1. This improvement can be ascribed to the suppression of electrolyte decomposition and transition metal ion dissolution by TMSPi, due to the preferential oxidation of TMSPi to electrolyte and the formation of a protective solid electrolyte interphase on LiNi1/3Co1/3Mn1/3O2, which are confirmed by electrochemical measurements and surface characterizations.

•Quinonyl compounds containing –OH groups are reported as cathode of sustainable Li-ion battery.•Lithiation potential of these compounds is positively correlated to -OH group number on them.•These compounds exhibit a discharge plateau of 3 V and deliver a capacity of over 180 mAh g-1 at 20 mA g-1.Suitably designed organic compounds are promising renewable electrode materials for lithium ion batteries (LIBs) with minimal environmental impacts and no CO2 release. Herein we report a series of polycarbonyl organic compounds with different number of hydroxyl groups, which can be obtained from renewable plants, as cathode materials for LIBs. Density functional theory (DFT) calculations based on the natural bond orbital (NBO) reveal a positive correlation between the reduction potentials and the number of hydroxyl groups, which is borne out experimentally. Anthraquinone (AQ) with three or four -OH groups has the structural advantages for improving the discharge plateaus. Mechanistic studies show that AQ containing neighbouring carbonyl groups and hydroxyl groups facilitates the formation of six or five-membered rings with lithium ion. Charge/discharge tests show that AQ, 1,5-DHAQ, 1,2,7-THAQ, and 1,2,5,8-THAQ can achieve initial discharge capacities of 215, 190, 186 and 180 mAh g-1 at a current density of 20 mA g-1, corresponding to 84%, 85%, 89% and 91% of their theoretical capacities, respectively.

•The cyclic stability of LiCoO2/graphite battery in voltage range of 3.0-4.5 V is improved by VEC.•VEC inhibits dimension change of the battery after cycling at 4.5 V cutoff voltage.•The SEI formed by VEC on cathode is able to inhibit the cobalt dissolution.•The anodic SEI formed by VEC suppresses the cobalt deposition and the electrolyte decomposition.We report a new finding that high voltage stability of lithium cobalt oxide (LiCoO2)/graphite battery can be improved by using vinyl ethylene carbonate (VEC) as an electrolyte additive. Charge/discharge tests demonstrate that the battery using VEC exhibits significantly improved cyclic and dimensional stability of the 053048-type LiCoO2/graphite pouch cell up to 4.5 V. The capacity retention is 87.0% and the swell value in thickness is 3.1% for the cell with 2.0 wt.% VEC after 400 cycles between 3.0 V and 4.5 V, compared to the values of 38.4% and 38.6%, respectively, for the cell without additive. The characterizations from scanning electron spectroscopy and X-ray photoelectron spectroscopy demonstrate that VEC facilitates the formation of stable solid electrolyte interfaces simultaneously on anode and cathode of the LiCoO2/graphite battery, yielding effective protections for anode and cathode and preventions of the electrolyte decomposition on both electrodes.

Oxidation-induced decomposition reactions of the representative complexes of propylene carbonate (PC)-based electrolytes were investigated using density functional theory (DFT) and a composite G4MP2 method. The cluster-continuum approach was used, where the oxidized PCn cluster was surrounded by the implicit solvent modeled via a polarized continuum model (PCM). The oxidative stability of the PCn (n = 2, 3, and 4) complexes was found to be around 5.4–5.5 V vs. Li+/Li, which is not only lower than the stability of an isolated PC but also lower than the stability of the PC–PF6−, PC–BF4− or PC–ClO4− complexes surrounded by the implicit solvent. The oxidation-induced decomposition reactions were studied. The decomposition products of the oxidized PC2 contained CO2, acetone, propanal, propene, and carboxylic acid in agreement with the previous experimental studies.

•Surface nature of carbon felt can be changed by heating or oxidation treatment.•Power of MFC is determined by anode morphology rather than oxygen-containing group.•Carbon felt with rougher surface exhibits better biocompatibility as anode of MFC.To clarify the role of carbon surface nature in the power generation of microbial fuel cell (MFC) based on carbon anode, three carbon felt samples, obtained by simple water cleaning (CCF), heating (HCF) and oxidation with ammonium persulfate (ACF), were characterized with SEM, BET, FTIR, cyclic voltammetry and acid titration, and their performances as anode of MFC were investigated with polarization curve measurement, chronoamperometry and chronopotentiometry. It is found that the power output of MFC depends on the morphology rather than the oxygen-containing group concentration of the carbon felt surface. CCF, HCF and ACF have their surface oxygen-containing groups of 1.52, 0.8 and 0.45 mM m−2 and specific surface areas of 0.33, 0.65 and 1.19 m2 g−1, but yield their maximal power densities of 606, 858 and 990 mW m−2, respectively. This study suggests that intensive attention should be paid to the design of surface morphology in order to improve power generation of MFC.

•TPFPP decreases the flammability and inhibits the oxidation of the electrolyte.•TPFPP is oxidized on LiMn2O4 electrode prior to the electrolyte.•TPFPP is reduced on graphite prior to the electrolyte.•TPFPP improves the thermal stability of the electrolyte.Tris (pentafluorophenyl) phosphine (TPFPP) additive possesses a dual functionality. The first of which is aimed at decreasing the flammability of the electrolyte, while the second is directed at the inhibition of the oxidative decomposition of electrolyte on cathode materials in lithium-ion batteries. The properties of the electrolyte containing TPFPP and the enhancements of cycling performance of Li/LiMn2O4 cells are investigated via a combination of electrochemical methods, self-extinguishing time (SET), differential scanning calorimeter (DSC), as well as density functional theory (DFT) computations. It is found that the incorporation of TPFPP to 1.0 M LiPF6 in 1:1:1 (v/v/v) ethylene carbonate/dimethyl carbonate/diethyl carbonate improves the thermal stability and decrease the flammability of the electrolyte. In addition, the initial discharge capacity and cycling stability of Li/LiMn2O4 is improved as well. The improved cycling performance with TPFPP added can be ascribed to the participation in surface layer formation process with incorporation of TPFPP. DFT theoretical computations are in good agreement with the modified cyclic voltammetry behavior of electrolyte with and without TPFPP additive on LiMn2O4 and graphite electrodes.

•Nano-Mo2C/CNTs composite was used as bifunctional anode electrocatalyst for microbial fuel cell.•CNTs are biocompatible and facilitate electron transfer via c-type cytochrome and nanowires.•Nano-Mo2C exhibits electrocatalytic activity towards the oxidation of metabolite hydrogen.•Composite yields a comparable activity to platinum as anode catalyst of microbial fuel cell.A novel electrode, carbon felt-supported nano-molybdenum carbide (Mo2C)/carbon nanotubes (CNTs) composite, was developed as platinum-free anode of high performance microbial fuel cell (MFC). The Mo2C/CNTs composite was synthesized by using the microwave-assisted method with Mo(CO)6 as a single source precursor and characterized by using X-ray diffraction and transmission electron microscopy. The activity of the composite as anode electrocatalyst of MFC based on Escherichia coli (E. coli) was investigated with cyclic voltammetry, chronoamperometry, and cell discharge test. It is found that the carbon felt electrode with 16.7 wt% Mo Mo2C/CNTs composite exhibits a comparable electrocatalytic activity to that with 20 wt% platinum as anode electrocatalyst. The superior performance of the developed platinum-free electrode can be ascribed to the bifunctional electrocatalysis of Mo2C/CNTs for the conversion of organic substrates into electricity through bacteria. The composite facilitates the formation of biofilm, which is necessary for the electron transfer via c-type cytochrome and nanowires. On the other hand, the composite exhibits the electrocatalytic activity towards the oxidation of hydrogen, which is the common metabolite of E. coli.

To improve the cyclability of a LiMn2O4/graphite lithium ion battery at elevated temperature, a carbonate-based electrolyte using prop-1-ene-1,3-sultone (PES) as additive was developed. The cycling performance of the LiMn2O4/graphite cell, based on the developed electrolyte at 60 °C, was evaluated by a constant current charge/discharge test, with comparison of the electrolyte using vinylene carbonate (VC) as additive. It was found that the cell based on the developed electrolyte exhibits better cyclability and exhibits better dimensional stability at elevated temperatures. The capacity retention is 91% and the swell value in thickness is 3.4% for the cell with PES after 150 cycles at 60 °C, while the respective values were 68% and 36.4% for the cell without additive, and 82% and 9.1% for the cell with VC. The results obtained from scanning electron spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, thermal gravimetric analysis, and molecular energy level calculations show that PES favors the formation of a stable solid electrolyte interphase, not only on the anode but also on the cathode of the LiMn2O4/graphite battery, effectively preventing electrolyte decomposition.

•DDS can dramatically improve the safety of Li-ion batteries during overcharge process.•No sacrifice on capacity and cycling stability with DDS incorporation.•Electro-polymerized layer can postpone the voltage rising up during overcharge state.The electrochemical properties and working mechanisms of dimethoxydiphenylsilane (DDS) as an electrolyte additive for overcharge protection of lithium ion batteries have been investigated by microelectrode cyclic voltammetry, galvanostatic charge-discharge cycling, and SEM observation on both the cathode and separator of the overcharged cells. DDS can be electrochemically polymerized when the cell was overcharged to 4.9 V (vs. Li/Li+), resulting in a polymer layer on the electrode and the separator, which increases the internal resistance of the cell and postpones the voltage rising up during the overcharge process. Therefore, the safety issue of lithium-ion batteries during overcharge state can be significantly improved by utilization of DDS. Furthermore, incorporation of DDS does not significantly degrade the performance of the cell as there is only a small capacity loss during the normal charge–discharge process.

The polyethylene (PE)-supported polymer membranes based on the blended polyvinylidene fluoride (PVDF) and cellulose acetate butyrate (CAB) are prepared for gel polymer electrolyte (GPE) of lithium ion battery. The performances of the prepared membranes and the resulting GPEs are investigated by scanning electron microscopy, electrochemical impedance spectroscopy, linear potential sweep, and charge–discharge test. The effect of the ratio of PVDF to CAB on the performance of the prepared membranes is considered. It is found that the GPE based on the blended polymer with PVDF:CAB = 2:1 (in weight) has the largest ionic conductivity (2.48 × 10−3 S cm−1) and shows good compatibility with anode and cathode of lithium ion battery. The LiCoO2/graphite battery using this GPE exhibits superior cyclic stability at room temperature, storage performance at elevated temperature, and rate performance.Highlights► A novel PE-supported PVDF/CAB polymer membrane was prepared. ► Excellent electrolyte uptake and ionic conductivity of GPE based on this membrane. ► Improved cycle, storage and rate performances of lithium ion battery using this GPE.

A novel LiMn0.8Fe0.2PO4/C composite is synthesized via a sol–gel process. In this composite, acetylene black is embedded in LiMn0.8Fe0.2PO4. The structure and morphology of the resulting composite are characterized with XRD, SEM, TEM, and BET, and its performance as the cathode of lithium ion battery is investigated by charge–discharge test and EIS, with a comparison of the sample prepared without embedding acetylene black. It is found that the embedded composite exhibits better performance than the non-embedded sample. The former delivers a reversible capacity of 160 mAh g−1, while the latter only 142 mAh g−1 at 0.1 C (1C = 150 mAh g−1 in the work). The embedded acetylene black not only functions as a barrier for the growing of LiMn0.8Fe0.2PO4 particles in the preparation process, which is important for the formation of nano-particles, but also helps build a stable conductive network, thus improving the charge–discharge performance of LiMn0.8Fe0.2PO4.Graphical abstractHighlights► A novel LiMn0.8Fe0.2PO4/C composite was synthesized by a simple sol–gel method. ► Acetylene black as carbon source was embedded in LiMn0.8Fe0.2PO4. ► The composite exhibits superior rate capability as cathode of Li-ion battery.

•TiO2-NCs electrode was constructed as anode of lithium ion microbattery.•Hierarchical structure of TiO2 with {001} facets yields good rate capability and cycle stability.•Highly mesoporous and microporous nature contributes to rate performance.TiO2 nanocones (TiO2-NCs) are constructed into arrayed spherical shells through a liquid-phase deposition reaction with polymer template, to improve the performance of TiO2 as anode of lithium ion microbattery. The morphology and structure characterizations indicate that TiO2 grows into nanocones with exposed {001} facets and is self-assembled into mesoporous structure. Meanwhile, macroporous channels are formed among the arrayed shells. Electrochemical measurements demonstrate that the TiO2-NCs reveal excellent performance in terms of improved lithium storage property and rate capability. The improved performance can be ascribed to the channel structure for the convenience of ionic transportation and the high-energy facets for the improvement of ionic reactivity.TiO2 nanocones (TiO2-NCs) were constructed into arrayed spherical shells to improve the performance of TiO2 as negative materials of lithium ion microbattery.

•A simple method to prepare α-MnO2 and δ-MnO2 for cathode materials of zinc-air battery is developed.•The as-prepared samples have larger specific surface area than commercial γ-MnO2.•The samples exhibit improved catalytic activity for oxygen reduction reaction compared to γ-MnO2.Four MnO2 samples were synthesized through a simple reaction of KMnO4 with high-purity graphite in different concentrations of sulfuric acid at low temperature. Their morphology, crystal structure and performance as cathode catalysts of zinc-air battery were investigated with X-ray diffraction (XRD), Fourier transformation infrared spectrometer (FTIR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) and electrochemical tests. It is found that the crystal structure and the morphology of the synthesized samples depend on the sulfuric acid concentration. The synthesized samples have large specific surface area and exhibit excellent performance compared to the commercial electrolytic manganese dioxide (γ-MnO2). Two varieties of manganese dioxides, δ-MnO2 (the as-prepared samples a and b) and α-MnO2 (the as-prepared sample c and d), were obtained when using low and high sulfuric acid concentration, respectively. Higher sulfuric acid concentration favors the agglomeration of the particles. The specific surface area of samples a, b, c, d, and γ-MnO2 is 83.2, 81.1, 88.5, 86.8, and 43.5 m2 g−1, corresponding to discharge capacity of zinc-air batteries is 169.5, 160.3, 175.2, 171.5, and 112.2 mAh, respectively.

•SEI formed by PES on NG was characterized with charge/discharge test, SEM, FTIR, and XPS.•NG in PC-based electrolyte can be well protected using PES.•Sulfur-containing species is the main component of the SEI formed by PES.•Preferable reduction of PES results in the formation of protective SEI on NG.The physical and chemical properties of the solid electrolyte interphase (SEI) formed by prop-1-ene-1,3-sultone (PES) on graphite anode in propylene carbonate (PC) based electrolyte for lithium ion battery were investigated by charge–discharge test, scanning electron spectroscopy with energy dispersive X-ray spectroscopy (SEM–EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). It is found that the charge–discharge performance of the cell LiCoO2/natural graphite (NG) using PC-based electrolyte containing 3 wt% PES is superior to that containing 6 wt% propane sultone (PS), an SEI formation additive that has the similar molecular structure to PES but is reduced not as easily as PES. The results from SEM–EDS, FTIR and XPS show that the structure of graphite has been protected and some S-containing species are proven to be components of the SEI, suggesting that the preferable reduction of PES plays an important role in the formation of a protective SEI on NG.

A new gel polymer electrolyte (GPE) system for lithium ion battery was developed by using anti-thermal shrinkagable nanoparticles/polymer incorporating with ionic liquid. Polyethylene-supported SiO2/poly(methyl methacrylate–acrylonitrile–vinyl acetate) (P(MMA–AN–VAc)) and Al2O3/P(MMA–AN–VAc) separators were prepared and the corresponding GPEs, SiO2/P(MMA–AN–VAc) + LiTFSI + PYR14TFSI/VC and Al2O3/P(MMA–AN–VAc) + LiTFSI + PYR14TFSI/VC, were obtained by immersing the separators in an ionic liquid electrolyte of 0.5 mol kg−1 LiTFSI in PYR14TFSI/VC. The structure and performance of the separators and corresponding GPEs were characterized by thermogravimetric analysis (TGA), air permeability, scanning electron spectroscopy (SEM), electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), cyclic voltammetry (CV) and charge–discharge test. It is found that the nanoparticles/polymer separators have good dimensional stability and the corresponding GPEs have good ionic conductivity and excellent compatibility with the electrodes of lithium ion battery. SiO2/P(MMA–AN–VAc) and Al2O3/P(MMA–AN–VAc) separators are stable up to 310 °C and have a Gurley value of 8 s. SiO2/P(MMA–AN–VAc) based GPE has an ionic conductivity of 1.2 × 10−3 S cm−1 at room temperature and an oxidative decomposition potential of 5.3 V (vs. Li/Li+). The interfacial resistance between anode lithium and GPE is changed from 47 Ω cm2 on the first day to 118 Ω cm2 after the 25 days. The battery Li/GPE/LiFePO4 shows good rate and cyclic performance.Highlights► Anti-thermal shrinkage nanoparticle/polymer and ionic liquid based GPE is developed. ► The nanoparticle/polymer separator has good dimensional stability. ► The GPE has good ionic conductivity and excellent compatibility with anode and cathode. ► Battery Li/GPE/LiFePO4 exhibits good rate and cycle performance.

•Stability of LNMO can be improved by limiting end-off discharge voltage to 4.0 V.•Capacity retention of LNMO after 500 cycles at 55 °C is improved from 17% to 85%.•The improvement is attributed to the limitation of LNMO particle separation.In this work, we proposed a new solution to the instability of LiNi0.5Mn1.5O4 cathode for lithium ion battery by simply controlling discharge end-off voltage. The morphology and the crystal structure of LiNi0.5Mn1.5O4 before and after cycling at elevated temperature were characterized with XRD and SEM, and its performances as cathode of lithium ion battery were investigated by cyclic voltammetry and galvanostatic charge–discharge tests. It is found that the cyclic stability of LiNi0.5Mn1.5O4 at elevated temperature is significantly improved by changing the end-off discharge voltage from 3.5 V to 4.0 V (vs. Li+/Li). After 500 cycles with 1 C rate at 55 °C, the capacity retention rate of LiNi0.5Mn1.5O4 is only 16.8% for the end-off discharge voltage of 3.5 V, but improves to 84.9% for 4.0 V. The improved stability is attributed to the limitation of the reduction of Mn4 + to Mn3 + that causes the primary particle separation of LiNi0.5Mn1.5O4.

A novel structure of anatase TiO2, nanocone-like TiO2 (TiO2-NC), is successfully prepared by a simple liquid-phase deposition method and is used as an anode material. The morphology and spatial arrangement of the TiO2-NC greatly affects the lithium storage, and TiO2-NC achieves a sustained high lithium storage performance (254.7 mA h g−1, corresponding to Li0.76TiO2) by assembling the TiO2-NC into ordered spherical shells. The structural analysis shows that exposed {001} facets of nanosized TiO2-NC help to increase the surface area as well as shorten the diffusion path of lithium transport. Moreover, an ordered arrangement of the TiO2-NC with a channel structure can further increase the surface area and improve the diffusion of the electrolyte, hence enhancing the lithium storage. Electrochemical tests indicate that the bulk intercalation of lithium was accompanied by the phenomenon of interfacial lithium storage in the TiO2-NC. In addition, the polarization of the TiO2-NC hollow spheres is effectively inhibited due to the ordered structure providing comfortable channels for the ionic and electronic diffusion, which imparts improved rate performance.

A composite, polyaniline (PANI)/mesoporous tungsten trioxide (m-WO3), was developed as a platinum-free and biocompatible anodic electrocatalyst of microbial fuel cells (MFCs). The m-WO3 was synthesized by a replicating route and PANI was loaded on the m-WO3 through the chemical oxidation of aniline. The composite was characterized by using X-ray diffraction, Fourier transform infrared spectrum, field emission scanning electron microscopy, and transmission electron microscopy. The activity of the composite as the anode electrocatalyst of MFC based on Escherichia coli (E. coli) was investigated with cyclic voltammetry, chronoamperometry, and cell discharge test. It is found that the composite exhibits a unique electrocatalytic activity. The maximum power density is 0.98 W m−2 for MFC using the composite electrocatalyst, while only 0.76 W m−2 and 0.48 W m−2 for the MFC using individual m-WO3 and PANI electrocatalyst, respectively. The improved electrocatalytic activity of the composite can be ascribed to the combination of m-WO3 and PANI. The m-WO3 has good biocompatibility and PANI has good electrical conductivity. Most importantly, the combination of m-WO3 and PANI improves the electrochemical activity of PANI for proton insertion and de-insertion.Highlights► Polyaniline/mesoporous tungsten trioxide composite was used as an anode electrocatalyst of microbial fuel cells. ► The tungsten trioxide provides the anode with biocompatibility. ► The electrochemical activity of polyaniline can be improved through its combination with the tungsten trioxide. ► The composite electrocatalyst exhibits a comparable activity to platinum in microbial fuel cells.

Polyethylene-supported polymethyl methacrylate/poly(vinylidene fluoride-co-hexafluoropropylene) separator for gel polymer lithium-ion battery use was prepared with a mixed solvent of n-butanol and acetone. The prepared separator was characterized with scanning electron spectroscopy and X-ray diffraction, and its performance was investigated by electrochemical impedance spectroscopy and battery charge/discharge test. Compared to the separator prepared with acetone, the separator prepared with the mixed solvent shows an enhanced porosity (from 42 to 49 %) and electrolyte uptake (from 104 to 125 %). The ionic conductivity of the corresponding gel polymer electrolyte is improved from 2.81 to 3.39 mS cm−1, the discharge capacity retention of the LiCoO2/artificial graphite battery is increased from 95 to 98 % after 100 cycles at 0.5 C, and the discharge capacity of the battery at 1 C increases by 4 %.

A facile method is developed for homogeneous dispersion of sulfur (S) nanoparticles in multi-walled carbon nanotubes (MWCNTs). The process involves the modification of MWCNTs via oxidation catalyzed by acid and the introduction of sulfur nanoparticles into the MWCNTs through direct precipitation. The resulting sample (precipitated S/MWCNTs) is characterized with scanning electron microscopy and thermogravimetric analysis, and its performance as cathode of lithium/sulfur battery is investigated with a comparison of the sample prepared by ball-milling (ball-milling S/MWCNTs). It is found that the precipitated S/MWCNTs exhibit better battery performance than the ball-milling S/MWCNTs. The initial discharge capacity is 1,299 mA h g−1 for the precipitated S/MWCNTs but only 839 mA h g−1 for ball-milling S/MWCNTs at 0.02 C. The capacity remains 800 mA h g−1 for the precipitated S/MWCNTs but only 620 mA h g−1 for ball-milling S/MWCNTs at 0.05 C after 50 cycles. The better performance of the precipitated S/MWCNTs results from the improved uniformity of S dispersed in MWCNTs through precipitation.

Sulfone-based electrolytes have attracted a great attention due to their high oxidation stability comparing to conventional carbonates. However, the ab initio calculated oxidation potentials (Eox) of isolated sulfones are lower than those for carbonates. To understand this contradiction, the oxidations of three carbonates and eleven sulfones in a presence of anions and other solvent molecules have been investigated by the density functional theory calculations with a polarized continuum model. Importantly, we found that the Eox of some of the sulfones show surprisingly high stability toward the presence of anions and another solvent, which is the key factor of high oxidation stability of these electrolytes compared to carbonates. Finally, the way to design new high oxidation stability sulfones by modifying their functional groups is discussed.Keywords: carbonates; density functional theory; electrolytes; oxidation stability; sulfones;

An attempt has been carried out here to use nanoconic TiO2 hollow spheres as buffers to accommodate the volume expansion of high-capacity materials. Based on the TiO2 hollow spheres, we tailor-designed a novel composite, in which the high Li+-transport dynamics of titanate hollow spheres (TiO2) and the high capacity of tin oxide (SnO2) were intimately integrated into a hierarchical architecture of nanocones, while the unique spatial arrangement of the SnO2 component in the nano-cavities effectively accommodates the volume change during lithiation/de-lithiation, hence rendering the composite stable cycling life. Electrochemical tests revealed favorable performances of the composite SnO2–TiO2 nanocones in terms of enhanced lithium storage capacity, stable cycle life and improved rate performance compared with each material components.

In this paper we report a novel lithium-sulfur cell, which is characteristic of a unique combination of carbon nanofibers–sulfur cathode and gel polymer electrolyte (GPE). In particular, the carbon nanofibers for the cathode and the poly(acrylonitrile)/poly(methyl methacrylate) (PAN/PMMA) membrane for the GPE are prepared by electrospinning technique. The GPE consists of electrospun PAN/PMMA membrane and 1 mol kg−1 lithium bis(trifluoromethylsulfonyl)imide in N-methyl-N-butylpiperidinium bis(trifluoromethanesulfonyl)imide (PPR14TFSI) and poly (ethylene glycol) dimethyl ether (PEGDME). The membrane and cell performances are investigated by scanning electron spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. It is found that the cell using the GPE based on PAN/PMMA membrane and PPR14TFSI-PEGDME (1:1) exhibits the largest discharge capacity and the best cycle durability. The discharge capacity of this cell remains at 760 mA h g−1 after 50 cycles. This new sulfur/electrolyte system combines the advantages of the carbon nanofibers that provide an effective conduction path and network-like structure, and the GPE that suppresses the dissolution of the intermediate products generated during the discharge process. The ratio of PPR14TFSI to PEGDME affects the ionic conductivity of the GPE, the stability of the sulfur electrode and the compatibility of lithium electrode with the GPE.Highlights► Fibrous PAN/PMMA membrane and carbon nanofibers were prepared by electrospinning technique. ► Improved performances of GPE based on PAN/PMMA incorporating with IL PPR14TFSI by adding PEGDME. ► Improved Li-sulfur battery performance by combining use of CNFs-S electrode and GPE with IL.

In this paper, we reported a novel solid electrolyte interphase (SEI) formation additive, prop-1-ene-1,3-sultone (PES), used in propylene carbonate (PC)-based electrolyte for lithium ion batteries. The effect of PES on the co-intercalation of PC into anode and the battery performance was investigated by energy calculation, cyclic voltammetry and battery charge–discharge test. The theoretical calculations and the voltammograms show that PES can be reduced prior to propane sultone (PS), a practical SEI formation additive for lithium ion batteries. Charge–discharge test shows that the use of PES can suppress successfully the co-intercalation of PC with lithium ions into graphite and the LiCoO2/graphite battery using PES exhibits better performance than that using PS as the SEI formation additive.Highlights► PES was used as an SEI formation additive in PC-based electrolyte for lithium ion battery. ► PES can be reduced prior to the start potential for the interaction between electrolyte and graphite electrode. ► The initial capacity loss of the battery was reduced. ► The cycle stability of the battery was improved.

Tris (pentafluorophenyl) phosphine (TPFPP) is used as an electrolyte additive to improve the cycling performance of high voltage (~ 5 V) lithium-ion battery. The electrochemical behaviors and surface chemistry of LiNi0.5Mn1.5O4 are investigated via cyclic voltammetry, chronoamperometry, charge–discharge test, X-ray photoelectron spectroscopy, and theoretical computations. It is found that the cycling performance of the cell Li/LiNi0.5Mn1.5O4, using an electrolyte of 1.0 M LiPF6 in ethylene carbonate/dimethyl carbonate/diethyl carbonate (1/1/1, in volume), can be improved by adding TPFPP into the electrolyte. The theoretical calculations predict that TPFPP is preferably oxidized compared to the solvents. Electrochemical measurements and XPS analyses show that a protective film is formed on LiNi0.5Mn1.5O4 when TPFPP is used, which contributes to the cycling performance improvement of the cell.Highlights► Significant improvement of cycling stability at 4.9 V with incorporation of TPFPP. ► Thinner surface layer formed on LiNi0.5Mn1.5O4 surface with TPFPP added electrolyte. ► More organic species formed on LiNi0.5Mn1.5O4 surface with TPFPP added electrolyte. ► Faster kinetics of Li-ion transport achieved with TPFPP containing electrolyte.

A unique porous carbon was prepared using a polymer mixture of polyacrylonitrile and poly(methylmethacrylate). Sulfur was incorporated into this porous carbon via a new simple solution chemical deposition method. This novel porous carbon–sulfur composite showed high reversible capacity, good capacity retention and good rate capability when used as the cathode in rechargeable Li/S cells. The electrochemical results show that porous carbon–sulfur composite with 53.7 wt.% S maintains a stable discharge capacity of more than 740 mA h g− 1-sulfur after 100 cycles.Highlights► A novel unique nanoporous carbon was prepared using a mixed polymer precursor. ► New simple solution preparation of nanoporous carbon–sulfur composites. ► Improved Li/S cell cycling stability and rate performance.

A composite of nickel and β-molybdenum carbide (Ni/β-Mo2C) was prepared from solution derived precursor and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Brunauer-Emmett-Teller (BET). The activity of Ni/β-Mo2C as noble-metal-free anodic electrocatalyst of microbial fuel cell (MFC) based on Klebsiella pneumoniae (K. pneumoniae) was investigated by electrochemical measurements. The results from voltammetric measurements show that Ni/β-Mo2C has high electrocatalytic activity towards the oxidation of formate, lactate, ethanol, and 2,6-di-tert-butyl-p-benzoquinon (2,6-DTBBQ), which are the main metabolites of K. pneumoniae. The results from polarization curve measurement indicate that the MFC using Ni/β-Mo2C as anodic electrocatalyst delivers a higher power density than the MFC using β-Mo2C as anodic electrocatalyst. Ni/β-Mo2C provides the MFC based on K. pneumoniae with a novel noble-metal-free anodic electrocatalyst of high activity.Highlights► Ni/β-Mo2C as noble-metal-free electrocatalyst. ► Microbial fuel cell based on K. pneumoniae. ► Electrocatalytic oxidation of metabolites. ► Improved power density output of the microbial fuel cell.

This paper reports a CO-tolerant electrocatalyst, mesoporous tungsten carbide-supported platinum (Pt/m-WC), for methanol oxidation. The support m-WC was synthesized by evaporation-induced triconstituent co-assembly method in which phenol formaldehyde polymer resin was used as the carbon precursor, tungsten hexachloride as the tungsten precursor and an amphiphilic triblock copolymers (P123) as the template. Nano-sized platinum particles were loaded on the m-WC to prepare Pt/m-WC. The structure and morphology of the prepared electrocatalyst were characterized by transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) and X-ray diffraction (XRD), and its activity toward methanol oxidation and its tolerance for CO were determined by cyclic voltammetry (CV) and chronopotentiometry (CP). It is found that the m-WC carburized at 900 °C(m-WC-900) has a larger specific surface area (182 m2 g−1) and a appropriate crystal structure compared to the m-WC carburized at 800 °C or 1000 °C, and thus is better as the support of platinum. The prepared Pt/m-WC-900 exhibits higher activity toward methanol oxidation and better tolerance for CO than Pt/Vulcan XC-72. The onset potential of CO electro-oxidation on Pt/m-WC is 0.449 V, which is more negative than that on Pt/Vulcan XC-72 (0.628 V).Highlights► WC as support of platinum electrocatalyst. ► CO-talerant electrocatalyst for methanol oxidation. ► Evaporation-induced triconstituent co-assembly builds mesoporous WC. ► Carburization temperature affects pore structure and electrocatalytic activity of WC.

Dandelion-like TiO2 microspheres consisting of numerous rutile single-crystalline nanorods were synthesized for the first time by a hydrothermal method. Their crystal structure, morphology and electrochemical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and galvanostatic charge and discharge tests. The results show that the synthesized TiO2 microspheres exhibit good rate and cycle performances as anode materials of lithium ion batteries. It can be found that the dandelion-like structure provides a larger specific surface area and the single-crystalline nanorod provides a stable structure and fast pathways for electron and lithium ion transport, which contribute to the rate and cycle performances of the battery.

A porous titania has been prepared by using polystyrene spheres and tri-block copolymer ((EO)20–(PO)70–(EO)20, P123) as templates, and its structure, composition, and performance as anode of lithium ion battery are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction, and galvanostatic charge/discharge test. The results from SEM and TEM indicate that the prepared porous titania has a trimodal pore system, in which the pores are in ordered arrangement and interconnected with the same pore diameter and uniform wall thickness. The charge/discharge tests show that the battery using the prepared porous titania as anode exhibits good rate capacity and cycle stability.

The reduction mechanism of ethylene sulfite (ES) in propylene carbonate (PC) based electrolyte is investigated using density functional theory in gas phase. Based on the electron affinity energy and lowest unoccupied molecular orbital (LUMO) energy, it can be known that free ES is reduced most easily compared with ES-Li+ and ES-Li+-PC, generating SO2 and propanal. However, the binding energy of ES-Li+ and ES-Li+-PC is quite negative, indicating that both of them are more possible in electrolyte solution than the free ES. The reductive decomposition products of ES-Li+ and ES-Li+-PC are OSO2Li, OSO2Li-R and ethylene. OSO2Li and OSO2Li-R are the main compositions of the solid electrolyte interphase film on the anode of lithium ion battery, which inhibits the reductive decomposition of PC. These calculations provide a detailed explanation on the experimental phenomena.

Polyethylene (PE)-supported poly(methyl methacrylate-vinyl acetate)-co-poly(ethylene glycol) diacrylate with and without doping nano-Al2O3, namely P(MMA-VAc)-co-PEGDA/PE and P(MMA-VAc)-co-PEGDA/Al2O3/PE, are prepared and their performances as gel polymer electrolytes (GPEs) for lithium ion battery are studied by mechanical test, scanning electron microscopy, thermogravimetric analyzer, electrochemical impedance spectroscopy, cyclic voltammetry, and charge/discharge test. It is found that the doping of nano-Al2O3 in the P(MMA-VAc)-co-PEGDA/PE improves the comprehensive performances of the GPE and thus the rate performance and cyclic stability of the battery. With doping nano-Al2O3, the mechanical and thermal stability of the polymer and the ionic conductivity of the corresponding GPE increases slightly, while the battery exhibits better cyclic stability. The mechanical strength and the decomposition temperature of the polymer increase from 15.9 MPa to 16.2 MPa and from 410 °C to 420 °C, respectively. The ionic conductivity of the GPE is from 3.4 × 10−3 S cm−1 to 3.8 × 10−3 S cm−1. The discharge capacity of the battery using the GPE with doping nano-Al2O3 keeps 90.9% of its initial capacity after 100 cycles and shows good C-rate performance.

A hierarchical porous carbon with low oxygen content has been prepared by using polystyrene (PS) spheres as template and its structure, composition and performances as anode of lithium ion battery are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, element analysis (EA), electrochemical impedance spectroscopy (EIS), and galvanostatic charge/discharge test. The results obtained from SEM, TEM, XRD, FTIR, and EA indicate that the prepared sample has a well-interconnected pore structure with a pore size of 170 nm and has an oxygen content of 3.3 ± 0.2 wt.%. The low oxygen content of the prepared sample can be ascribed to the low decomposition temperature of the template that was determined by thermal analysis. EIS shows that the prepared sample has lower electrochemical impedance for the lithium insertion/de-insertion than commercial natural graphite and charge/discharge tests show that the battery using the prepared sample as anode exhibits better rate performance than that using the graphite.

Lithium difluoro (oxalate) borate (LiDFOB) is used as thermal stabilizing and solid electrolyte interface (SEI) formation additive for lithium-ion battery. The enhancements of electrolyte thermal stability and the SEIs on graphite anode and LiFePO4 cathode with LiDFOB addition are investigated via a combination of electrochemical methods, nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared-attenuated total reflectance (FTIR-ATR), as well as density functional theory (DFT). It is found that cells with electrolyte containing 5% LiDFOB have better capacity retention than cells without LiDFOB. This improved performance is ascribed to the assistance of LiDFOB in forming better SEIs on anode and cathode and also the enhancement of the thermal stability of the electrolyte. LiDFOB-decomposition products are identified experimentally on the surface of the anode and cathode and supported by theoretical calculations.

A new gel polymer electrolyte (GPE) is reported in this paper. In this GPE, blending polymer of poly(ethylene oxide) (PEO) with poly(vinylidene fluoride-hexafluoropropylene) (P(VdF-HFP)), doped with nano-Al2O3 and supported by polypropylene (PP), is used as polymer matrix, namely PEO–P(VdF-HFP)–Al2O3/PP. The performances of the PEO–P(VdF-HFP)–Al2O3/PP membrane and the corresponding GPE are characterized with mechanical test, CA, EIS, TGA and charge–discharge test. It is found that the performances of the membrane and the GPE depend to a great extent on the content of doped nano-Al2O3. With doping 10 wt.% nano-Al2O3 in PEO–P(VdF-HFP), the mechanical strength from 9.3 MPa to 14.3 MPa, the porosity of the membrane increases from 42% to 49%, the electrolyte uptake from 176% to 273%, the thermal decomposition temperature from 225 °C to 355 °C, and the ionic conductivity of corresponding GPE is improved from 2.7 × 10−3 S cm−1 to 3.8 × 10−3 S cm−1. The lithium ion battery using this GPE exhibits good rate and cycle performances.

Nine 3D heterometallic coordination polymers, namely [NaLn2Cu6I5(IN)6(ox)(H2O)4]·H2O [Ln = La (1), Eu (2), Gd (3), Tb (4), HIN = isonicotinic acid, ox = oxalate], [Ln2Ag4(IN)5(ox)2(NO3)(H2O)2]·3H2O [Ln = Dy (5), (6) Ho], [LnAg(IN)2(ox)]·H2O [Ln = La (7), Pr (8), Tm (9)] have been successfully synthesized under hydrothermal conditions. Compounds 1–4 exhibit same unusual 3D pillared-layer heterometallic coordination frameworks that are built up by the Ln-ox-Na layers, 2D inorganic [(Cu6I5)+]n layers and IN ligands. Compounds 5 and 6 represent 3D coordination frameworks that are constructed from rare Ln(III)-ox-IN chains and Ag(I)-IN-ox layers. 3D coordination networks of compounds 7–9 are built up from 2D Ln(III)-IN-ox layers and Ag(I)-IN-ox subunits. Furthermore, the magnetic properties of compounds 5 and 6 and the luminescence properties of compounds 2, 4 and 5 have been investigated.

Arrayed porous iron-doped TiO2 with controllable pore size was prepared by using polystyrene spheres and its structure, morphology, composition and photoelectrochemical properties were characterized with X-ray diffraction, scanning electron microscope, inductively coupled plasma-atomic emission spectrometer and electrochemical methods. It is found that the photoelectrochemical properties of the arrayed porous TiO2 can be improved by doping adequate amount of iron in the lattice of TiO2 and the sample doped with 0.01 wt% Fe (based on Ti) exhibits the best photoelectrochemical performance. With doping 0.01 wt% Fe in TiO2, the photocurrent density of the sample is improved from 2.0 μA cm−2 to 10.0 μA cm−2 and its flat-band potential shifts from −0.38 V to −0.55 V (vs. SCE).Highlights► Arrayed porous iron-doped TiO2. ► Photoelectrocatalyst for hydrogen generation. ► Pore size and iron content affect the photocatalytic activity. ► Smaller pore size is preferable for the activity improvement. ► Adequate content of iron is needed to reach a high activity.

The synergism of imidazole (IMZ) and poly(ethylene glycol) 600 (PEG) for zinc corrosion inhibition in 3 mol L−1 KOH solution was investigated using a combination of electrochemical and gravimetric methods, and the surface morphology of the zinc was observed by scanning electron microscopy. It is found that there is a synergistic effect between IMZ and PEG for the zinc corrosion inhibition. The difference in molecular structure, ring for IMZ and chain for PEG, and in binding atoms with zinc, nitrogen in IMZ and oxygen in PEG, contributes to this synergistic effect. IMZ inhibits zinc corrosion by mainly depressing the anodic reaction, whereas PEG by depressing the cathodic reaction. The storage performance of the zinc–manganese dioxide batteries using IMZ and/or PEG as inhibitors was determined by discharge test, with a comparison of the battery using mercury as the inhibitor. The battery containing 0.05% IMZ + 0.05% PEG exhibits better performance than the mercury-containing battery, especially when discharged at high rate.Highlights► An kind of environmentally benign organic composite additives is used firstly. ► The corrosion of zinc is inhibited used the organic compound as additive. ► The rate performance of the battery used the organic compound as additive is improved. ► The synergism of composite additives for zinc corrosion inhibition is investigated.

Dimethylacetamide (DMAc) is used as an electrolyte stabilizing additive for lithium ion battery. The effects of DMAc on the enhancements of electrolyte thermal stability and the solid electrolyte interphases (SEIs) on graphite anode and LiFePO4 cathode were investigated via a combination of electrochemical methods, nuclear magnetic resonance (NMR), Fourier transform infrared-attenuated total reflectance (FTIR-ATR), as well as X-ray photoelectron spectroscopy (XPS). It was found that 1.0 M LiPF6 EC/DMC/DEC (1/1/1,weight ratio) electrolyte with 1% DMAc incorporation can be stable at 85 °C for over 6 months without precipitation and color change. In addition, the addition of 1% dimethylacetamide (DMAc) can significantly improve the cyclic performance of a LiFePO4/graphite cell at elevated temperature. These improved performances are ascribed to the enhancement of the thermal stability of the electrolyte and the modification of SEI components on graphite anode and LiFePO4 cathode. The explicit working mechanism of DMAc stabilizing LiPF6-based electrolyte is also discussed by the density functional theory (DFT) calculations.

The effect of sodium benzoate on the electrodeposition of zinc on carbon steel electrode from acidic chloride solution was studied by cyclic voltammetry (CV), differential capacitance (DC), chronoamperometry (CA), scanning electron microscopy (SEM), and X-ray diffraction (XRD). A dimensionless graph model was used to analyze the nucleation process of zinc. It is found that the sodium benzoate has a blocking effect on the zinc electrodeposition when its concentration is higher than 0.03 M but will accelerate the formation rate of zinc nuclei when its concentration is lower than 0.03 M. Benzoate can be adsorbed on the surface of the electrode, which reduces the interface tension of electrode/solution and favors the formation and growth of zinc nuclei when its concentration is lower than 0.03 M, but forms a separated layer and retards the formation and growth of zinc nuclei when its concentration is higher than 0.03 M.

Polyethylene glycol 600 (PEG 600) and polysorbate 20 (Tween 20) were used as a composite corrosion inhibitor of zinc in alkaline solution for the first time. The effects of the composite and individual inhibitors on corrosion inhibition of zinc were evaluated by weight-loss analysis and electrochemical methods including potentiodynamic, potentiostatic, and electrochemical impedance spectroscopic measurements. It was found that there was a synergistic effect between PEG 600 and Tween 20 on corrosion inhibition of zinc. The corrosion inhibition efficiency of the composite inhibitor, 500 ppm PEG 600 + 500 ppm Tween 20, was 89%, much higher than that of the individual inhibitor, 1000 ppm Tween 20 (71%) or 1000 ppm PEG 600 (55%). The battery (Zn/MnO2) discharge performance tests showed that the composite inhibitor reduced the self-discharge of zinc anode more effectively than the individual inhibitor. The synergistic mechanism between PEG 600 and Tween 20 was discussed.

The effect of substituents on the oxidation potential for the one-electron reaction of 1,4-dimethoxybenzene was understood with a theoretical calculation based on density functional theory (DFT) at the level of B3LYP/6-311+G(d). It is found that the oxidation potential for the one-electron reaction of 1,4-dimethoxybenzene is 4.13 V (vs Li/Li+) and can be changed from 3.8 to 5.9 V (vs Li/Li+) by substituting electron-donating or electron-withdrawing groups for the hydrogen atoms on the aromatic ring. These potentials are in the range of the limited potentials for the lithium ion batteries using different cathode materials, and thus the substituted compounds can be selected as the redox shuttles for the overcharge prevention of these batteries. The oxidation potential of 1,4-dimethoxybenzene decreases when the hydrogen atoms are replaced with electron-donating groups but increases when replaced with electron-withdrawing groups. The further oxidation of these substituted compounds was also analyzed on the basis of the theoretic calculation.

TiO2-coated SnO2 (TCS) hollow spheres, which are new anode materials for lithium ion (Li-ion) batteries, were prepared and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), and galvanostatic charge/discharge tests. The results obtained from XRD, SEM, and TEM show that TiO2 can be uniformly coated on the surface of SnO2 hollow spheres with the assistance of anionic surfactant. The cyclic voltammograms indicate that both TiO2 and SnO2 exhibit the activity for Li-ion storage. The charge/discharge tests show that the prepared TCS hollow spheres have a higher reversible coulomb efficiency and a better cycling stability than the uncoated SnO2 hollow spheres.

In this paper, we report a successful synthesis of porous ZnCo2O4 nanoflakes by a morphology-conserved and pyrolysis-induced transformation of novel hexagonally shaped, highly ordered, and inorganic–organic–inorganic layered hybrid nanodisks. It is shown that the hexagonal hybrid nanodisks are constructed from organic molecule (ethylene glycol)-directed assembly of inorganic bilayers. The assembly mechanism has been established by a number of structural and spectroscopic techniques. The porous ZnCo2O4 nanoflakes have also been tested as a lithium ion battery electrode, showing high capacity and high cyclability.

A highly effective hydroxylated-functionalization of carbon fibres for use as electrodes of all-vanadium redox flow battery (VRFB) was developed. Carbon paper made of carbon fibres was hydroxylated ultrasonically with mixed acids (H2SO4/HNO3, VH2SO4/VHNO3VH2SO4/VHNO3 = 3/1) in a Teflon-lined stainless steel autoclave for different time at 80 °C. The structure, composition, and electrochemical properties of the treated samples for positive and negative electrodes of VRFB were characterized with Fourier transformation infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectrometry, scanning electron microscopy, X-ray diffraction, cyclic voltammetry, electrochemical impedance spectroscopy, and cell charge and discharge tests. The content of hydroxyl group changes from 3.8% for the untreated sample to 14.3% for the carbon paper treated in mixed acids for 10 h. The highly hydroxylated sample shows its high activity toward the redox reactions of V(II)/V(III) and V(IV)/V(V). The VRFB using the carbon paper treated for 8 h as the electrodes exhibits excellent performance under a current density of 10 mA cm−2. The average voltage efficiency reaches 91.3%, and the average energy efficiency reaches 75.1%. The mechanisms for the high hydroxylation of the carbon fibres with the mixed acids and the high activity of the treated sample toward the vanadium redoxs are discussed.

A new gel polymer electrolyte (GPE), fumed silica-doped poly(butyl methacrylate-styrene) (P(BMA-St))-based gel polymer electrolyte, was developed for lithium ion battery. The copolymer P(BMA-St) was synthesized by emulsion polymerization, the copolymer membranes doped with and without fumed silica were prepared through phase inversion, and the GPEs were obtained by immersing the membranes in 1 M LiPF6 solution. The structure and performances of the copolymer, the membranes and the GPEs were characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), scanning electron spectroscopy (SEM), thermogravimetric analysis (TGA), linear sweep voltammetry (LSV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). The copolymer P(BMA-St) is formed through the breaking of the double bond CC in the monomers, butyl methacrylate and styrene. By doping 10 wt.% fumed silica in P(BMA-St) membrane, the properties of the membrane and the corresponding GPE were improved. The membrane doped with fumed silica is stable up to 355 °C and its pore size becomes more uniform and smaller; oxidative decomposition potential of the GPE doped with fumed silica is raised to 5.2 V (vs. Li/Li+) and its ionic conductivity is as high as 2.15 × 10−3 S cm−1 at ambient temperature.

A lithium-organic coordination compound based on an aromatic carbonyl derivative, [Li2(C14H6O4)], was synthesized by the dehydration of [Li2(C14H6O4)·H2O], and used as a novel lithium-inserted material for lithium ion batteries. The synthesized material has initial discharge capacity of 126 and 115 mAh/g at current densities of 22 and 111 mAh/g, corresponding to the columbic efficiency of 99.2% and 98.3% at the first cycle, and its capacity fading is only 5% and 13% after 50 cycles, respectively, showing that this compound is a promising candidate as lithium-inserted material for lithium ion batteries.

4,5-Dimethyl-[1,3]dioxol-2-one (DMDO) was used as a novel electrolyte additive for lithium-ion batteries. The effect of DMDO on the formation of the solid electrolyte interface (SEI) on anode and cathode of MCMB/LiNi0.8Co0.2O2 cells was investigated via a combination of electrochemical methods, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. It is found that cells with electrolyte containing 2% DMDO have better capacity retention than cells without DMDO and this improved performance is ascribed to the assistance of DMDO in forming better SEIs on anode and cathode. DMDO-decomposition products are identified experimentally on the surface of the anode and cathode and supported by theoretical calculations.

In this paper, we reported a novel electrocatalyst, Vulcan XC-72-supported porous platinum nano-particles (Ptp/C) for methanol oxidation. In the preparation of Ptp/C, platinum precursor was first adsorbed on carbon and then reduced by l-ascorbic acid in ethylene glycol solution. The structure and morphology of Ptp/C and its activity toward methanol oxidation were characterized by transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) measurement, X-ray diffraction (XRD), energy-dispersion spectrometer (EDS), cyclic voltammetry (CV), and chronoamperometry (CA), with a comparison of the electrocatalyst prepared with sodium borohydride as reducer (Pts/C). It is found that both electrocatalysts have similar particle size but have different surface morphology of platinum and thus exhibit different electrocatalytic activity toward methanol oxidation. The platinum particle size of both electrocatalysts is 3–5 nm, but the corresponding BET surface areas are different significantly, 131.6 m2 g−1 and 87.7 m2 g−1 for Ptp/C and Pts/C, respectively, indicative of the porous structure of platinum particles in Ptp/C. The peak current for methanol oxidation on CV is 167 mA mg−1 and 44 mA mg−1 for Ptp/C and Pts/C, respectively, indicative of the high electrocataytic activity of Ptp/C toward methanol oxidation. The result from CA shows that Ptp/C has good stability as the electrocatalyst for methanol oxidation.

Carbon nanotube (CNT)-supported platinum modified with HxMoO3 (Pt-HxMoO3/CNT) was prepared and used as an electrocatalyst for methanol oxidation. In the preparation of this electrocatalyst, a platinum precursor was loaded on CNTs and reduced by sodium borohydride in ethylene glycol, resulting in CNT-supported platinum without modification (Pt/CNT), and then the Pt/CNT was modified with HxMoO3 that was formed by hydrolysis and subsequent reduction of ammonium molybdate. The surface morphology, structure and composition of Pt-HxMoO3/CNT and Pt/CNT as well as their activity toward methanol oxidation were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive spectrometry (EDS), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), chronoamperometry (CA), chronopentiometry (CP), and electrochemical impedance spectroscopy (EIS). The results, obtained from TEM, XRD, EDS, and FTIR, indicate that the platinum loaded on CNTs has a face-centered cubic structure with particle sizes of 2–5 nm, and the modification of HxMoO3 on platinum with an atom ratio of Pt:Mo = 2:1 has little effect on the particle size, distribution and structure of the platinum. The results, obtained from CV, CA, CP, and EIS, show that the Pt-HxMoO3/CNT exhibits higher electrocatalytic activity toward methanol oxidation and better carbon monoxide tolerance than Pt/CNT.

A pure β-molybdenum carbide (Mo2C) with a Brunauer–Emmett–Teller (BET) special surface area of 77.5 m2/g, prepared by solution derived precursor, was used as anodic catalyst of microbial fuel cell (MFC) based on Klebsiella pneumoniae (K. pneumoniae). The electrochemical activity of the prepared Mo2C and the performance of the MFC were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and polarization curve measurement. The results show that the prepared Mo2C has high electrocatalytic activity and is a potential alternative to platinum as the anodic catalyst of MFCs. The maximum power density of single-cube MFC with 6.0 mg/cm2 Mo2C as anodic catalyst is 2.39 W/m3. This power density is far higher than that of the MFC with carbon felt as anode without any catalyst (0.61 W/m3), and comparable to that of the MFC using 0.5 mg/cm2 Pt as anodic catalyst (3.64 W/m3).

With the assistance of nonionic surfactant (OP-10) and surface-selective surfactant (CH3COOH), anatase TiO2 was prepared as an anode material for lithium ion batteries. The morphology, the crystal structure, and the electrochemical properties of the prepared anatase TiO2 were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and galvanostatic charge and discharge test. The result shows that the prepared anatase TiO2 has high discharge capacity and good cyclic stability. The maximum discharge capacity is 313 mAh·g−1, and there is no significant capacity decay from the second cycle.

This paper reported on a new gel polymer electrolyte (GPE) based on polyethylene (PE) non-woven fabric supported poly(acrylonitrile-vinyl acetate) (P(AN-VAc)/PE) membrane for lithium ion battery use. The preparation and performances of the P(AN-VAc)/PE membrane and its GPE based on 1 M LiPF6 in dimethyl carbonate/diethylene carbonate/ethylene carbonate (1:1:1 in volume) were investigated with a comparison of the unsupported P(AN-VAc) membrane. It is found that the P(AN-VAc)/PE membrane shows better mechanical strength and pore structure for electrolyte uptake than the P(AN-VAc) membrane, and subsequently the GPE based on P(AN-VAc)/PE exhibits higher ionic conductivity and electrochemical stability on cathode than the GPE based on P(AN-VAc). With the support of the non-woven fabric, the ionic conductivity of the GPE at room temperature increases from 1.4 to 3.8 mS cm−1, the oxidation decomposition potential of the GPE on a stainless steel is improved from 5.0 to 5.6 V (vs. Li/Li+). The mesocarbon microbeads (MCMB)/LiMn2O4 battery using P(AN-VAc)/PE as separator retains 94% of its initial discharge capacity after 100 cycles at C/2 rate, showing that the P(AN-VAc)/PE membrane is a possible alternative to the expensive separator for current liquid lithium ion battery.

In this paper, we reported an improved process for the preparation of PtRu/CNTs, which involves the adsorption of Pt and Ru ions on CNTs in aqueous solution and the reduction of the adsorbed Pt and Ru ions on CNTs in ethylene glycol. The surface morphology, structure, and compositions of the prepared catalyst were studied by transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy-dispersive spectrometer. TEM observation showed that the particles size of the prepared PtRu alloy was in the range of 2–5 nm, XRD patterns confirmed a face-centered cubic crystal structure. The activity and stability of the prepared catalyst toward methanol oxidation were studied in 0.5 M H2SO4 + 1 M CH3OH solution by cyclic voltammetry, chronoamperometry, and chronopotentiometry. The electrochemical results showed that the prepared catalyst exhibited higher activity and stability toward methanol oxidation than commercial PtRu/C with the same loading amount of Pt and Ru.

Nano-Al2O3 was doped in poly(acrylonitrile-co-methyl methacrylate) (P(AN-co-MMA)), and polyethylene(PE)-supported P(AN-co-MMA)/nano-Al2O3 microporous composite polymer electrolyte (MCPE) was prepared. The performances of the prepared MCPE for lithium ion battery use, including ionic conductivity, electrochemical stability, interfacial compatibility, and cyclic stability, were studied by scanning electron spectroscopy, linear sweep voltammetry, and electrochemical impedance spectroscopy. It is found that the nano-Al2O3 significantly affects the MCPE performances. Compared to the MCPE without any nano-Al2O3, the MCPE with 10 wt.% nano-Al2O3 reaches its best performances. Its ionic conductivity is improved from 2.0 × 10−3 to 3.2 × 10−3 S cm−1, its decomposition potential is enhanced from 5.5 to 5.7 V (vs Li/Li+), and its interfacial resistance on lithium is reduced from 520 to 160 Ω cm2. Thus, the battery performance is improved.

Self-supported gel polymer electrolyte (GPE) was prepared based on copolymer, poly(methyl methacrylate–acrylonitrile–vinyl acetate) (P(MMA–AN–VAc)). The copolymer P(MMA–AN–VAc) was synthesized by emulsion polymerization and the copolymer membrane was prepared through phase inversion. The structure and the performance of the copolymer, the membrane and the GPE were characterized by FTIR, NMR, SEM, XRD, DSC/TG, LSV, CA, and EIS. It is found that the copolymer was formed through the breaking of double bond CC in each monomer. The membrane has low crystallinity and has low glass transition temperature, 39.1 °C, its thermal stability is as high as 310 °C, and its mechanical strength is improved compared with P(MMA–AN). The GPE is electrochemically stable up to 5.6 V (vs. Li/Li+) and its conductivity is 3.48 × 10−3 S cm−1 at ambient temperature. The lithium ion transference number in the GPE is 0.51 and the conductivity model of the GPE is found to obey the Vogel–Tamman–Fulcher (VTF) equation.

Here we report the preparation of LiFePO4 cathode for lithium ion battery in the aqueous solvent with polyacrylic acid (PAA) as a binder. Its performances were studied by cyclic voltammetry (CV), charge–discharge cycle test, electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD), and scanning electron microscopy (SEM), and compared with the cathode prepared in N-methyl-2-pyrrolidone (NMP) solvent by using polyvinylidene fluoride (PVDF) as a binder. It is found that the cathode prepared in the aqueous solvent shows better performances than that in NMP solvent, including the better reversibility, the smaller resistances of solid electrolyte interphase and charge exchange, the less polarization, higher capacity and cyclic stability for lithium ion intercalation in or de-intercalation from LiFePO4. The aqueous solvent is also more environmental friendly and cheaper than NNP. In addition, PAA is less costly than PVDF. Consequently, the preparation of LiFePO4 cathode in the aqueous solvent by using a PAA binder provides lithium ion battery with improved performances at a less cost and in a more environmental friendly way.

A detailed investigation of the effect of the thermal stabilizing additive, propane sultone (PS), on the reactions of the electrolyte with the surface of the electrodes in lithium-ion cells has been conducted. Cells were constructed with meso-carbon micro-bead (MCMB) anode, LiNi0.8Co0.2O2 cathode and 1.0 M LiPF6 in 1:1:1 EC/DEC/DMC electrolyte with and without PS. After formation cycling, cells were stored at 75 °C for 15 days. Cells containing 2% PS had better capacity retention than cells without added PS after storage at 75 °C. The surfaces of the electrodes from cycled cells were analyzed via a combination of TGA, XPS and SEM. The addition of 2% PS results in the initial formation of S containing species on the anode consistent with the selective reduction of PS. However, modifications of the cathode surface in cells with added PS appear to be the source of capacity resilience after storage at 75 °C.

Fumed silica was used as a dopant in the preparation of poly(methyl methacrylate-acrylonitrile-vinyl acetate) (P(MMA-AN-VAc)) to improve the ionic conductivity of the P(MMA-AN-VAc)-based gel polymer electrolyte (GPE). The performance of the P(MMA-AN-VAc) membrane and its GPE for lithium ion battery use were studied by XRD, SEM, TGA, LSV, CA, EIS, and charge/discharge test. It is found that the doping of fumed silica in the P(MMA-AN-VAc) changes the membrane from semi-crystal to amorphous state and the pore structure of the membrane. By the doping of 10 wt.% fumed silica in the membrane, the porosity of the membrane increases with the pore dispersed more uniformly and interconnected and having higher electrolyte uptake, resulting in the improvement in ionic conductivity of the GPE from 3.48 × 10−3 to 5.13 × 10−3 S cm−1 at ambient temperature. On the other hand, the thermal stability of the membrane, the electrochemical stability of the GPE, and the cyclic performance of the battery are also improved.

A series of novel Co–S–B systems were prepared by simple chemical reduction method as the anode material for secondary alkaline batteries. The prepared samples were investigated by inductivity coupled plasma optical emission spectrum (ICP), Brunauer–Emmetr–Teller (BET) method, scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray energy dispersive spectroscopy (EDS) and charge–discharge method. It was found that the BET surface area of Co–S–B system increases and its particle size decreases with increasing the sulfur content. Sulfur incorporation suppresses initial capacity fading of Co–B compound due to irreversible dissolution of boron, and Co–S–B electrodes show enhanced electrochemical capacity and excellent cycle performance. The discharge capacity of Co75.4B17S7.6 reaches 513.6 mAh/g at a moderate current density of 100 mA/g and 470 mAh/g after 60 cycles, which is about 1.5 times that of conventional AB5-type alloy. A proper mechanism was proposed to explain the electrochemical reaction process of Co–S–B electrode.

The result obtained from linear potential sweep indicates that magnesium in 6 M KOH solution behaves like an active–passive metal. The anodic oxidation process of magnesium and the interface structure between magnesium and solution were investigated by alternative current impedance analysis. It is found that when anodized, magnesium experiences active dissolution, passivation and secondary oxidation. In active region, magnesium dissolves actively, which is controlled by charge transfer step. In passive region, magnesium is passivated by the deposited Mg(OH)2 but its oxidation controlled by charge transfer step still happens. In the secondary oxidation region, magnesium is oxidized directly to MgO, which is mix-controlled by charge transfer step and diffusion of water.

Magnesium and nickel alloy was prepared electrochemically in dimethylsulfoxide (DMSO) solution. Its structure, composition and property for hydrogen storage were studied by SEM, ICP, XRD, and charge and discharge test. It is found that codeposition of magnesium and nickel can take place at the potentials from −2.0 to −3.2 V (vs. Ag/Ag+) in 0.15 M LiClO4 + DMSO solution containing MgCl2 and NiCl2. The surface morphology and the hydrogen storage capacity of the prepared alloy are influenced by the deposition potential. The alloy prepared at −2.4 V (vs. Ag/Ag+) is mainly composed of Mg2Ni phase and shows its best electrochemical capacity of 361.8 mAh g−1, corresponding to a hydrogen storage capacity of 1.35 wt.%.

The electrochemical oxidative stability of solvent molecules used for lithium ion battery, ethylene carbonate (EC), propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate in the forms of simple molecule and coordination with anion PF6−, is compared by using density functional theory at the level of B3LYP/6-311++G (d, p) in gas phase. EC is found to be the most stable against oxidation in its simple molecule. However, due to its highest dielectric constant among all the solvent molecules, EC coordinates with PF6− most strongly and reaches cathode most easily, resulting in its preferential oxidation on cathode. Detailed oxidative decomposition mechanism of EC is investigated using the same level. Radical cation EC•+ is generated after one electron oxidation reaction of EC and there are five possible pathways for the decomposition of EC•+ forming CO2, CO, and various radical cations. The formation of CO is more difficult than CO2 during the initial decomposition of EC•+ due to the high activation energy. The radical cations are reduced and terminated by gaining one electron from anode or solvent molecules, forming aldehyde and oligomers of alkyl carbonates including 2-methyl-1,3-dioxolane, 1,3,6-trioxocan-2-one, 1,4,6,9-tetraoxaspiro[4.4]nonane, and 1,4,6,8,11-pentaoxaspiro[4.6]undecan-7-one. The calculation in this paper gives a detailed explanation on the experimental findings that have been reported in literatures and clarifies the mechanism on the oxidative decomposition of EC.

The detailed oxidative decomposition mechanism of propylene carbonate (PC) in the lithium ion battery is investigated using density functional theory (DFT) at the level of B3LYP/6-311++G(d), both in the gas phase and in solvent. The calculated results indicate that PC is initially oxidized on the cathode to a radical cation intermediate, PC•+, and then decomposes through three pathways, generating carbon dioxide CO2 and radical cations. These radical cations prefer to be reduced on the anode or by gaining one electron from PC, forming propanal, acetone, or relevant radicals. The radicals terminate by forming final products, including trans-2-ethyl-4-methyl-1,3-dioxolane, cis-2-ethyl-4-methyl-1,3-dioxolane, and 2,5-dimethyl-1,4-dioxane. Among all the products, acetone is most easily formed. The calculations in this paper give detailed explanations of the experimental findings that have been reported in the literature and clarify the role of intermediate propylene oxide in PC decomposition. Propylene oxide is one of the important intermediates. As propylene oxide is formed, it isomerizes forming a more stabile product, acetone.

In this work, based on First-principle plane wave pseudo-potential method, we have carried out an in-depth study on the possible dead lithium phase of Sn-Zn alloy as anode materials for lithium ion batteries. Through investigation, we found that the phases LixSn4Zn4(x = 2, 4, 6, 8) contributed to reversible capacity, while the phases LixSn4Zn8−(x−4)(x = 4.74, 7.72) led to capacity loss due to high formation energy, namely, they were the dead lithium phases during the charge/discharge process. And we come up with a new idea that stable lithium alloy phase with high lithiation formation energy (dead lithium phase) can also result in high loss of active lithium ion, besides the traditional expression that the formation of solid electrolyte interface film leads to high capacity loss.

To improve the safety of lithium-ion batteries, cresyl diphenyl phosphate (CDP) was used as a flame retardant additive in a LiPF6 electrolyte solution. The flammability of the electrolytes containing CDP and the electrochemical performances of the cells, LiCoO2/Li, graphite/Li and the battery LiCoO2/graphite with these electrolytes, were studied by measuring the self-extinguishing time of the electrolytes, the variation of surface temperature of the battery and the charge/discharge curve of the cells or battery. It is found that the addition of CDP to the electrolyte provides a significant suppression in the flammability of the electrolyte and an improvement in the thermal stability of battery. On the other hand, the electrochemical performances of the cells become slightly worse due to the application of CDP in the electrolyte. This alleviated trade-off between the flammability and thermal stability and cell performances provides a possibility to formulate a nonflammable electrolyte by using CDP.

The electrochemical characterization and overcharge protection mechanism of cyclohexyl benzene as an additive in electrolyte for lithium ion battery was studied by microelectrode cyclic voltammetry, Galvanostatic charge–discharge measurements and SEM observation on both the cathode and separator of the overcharged cells. It was found that when the battery is overcharged, cyclohexyl benzene electrochemically polymerized to form polymer between separator and cathode at the potentials lower than that for electrolyte decomposition. The polymer blocks the overcharging process of the battery. The additive causes a small capacity loss and impedance increase in a real cell, but that can be mitigated if the operating voltage is much lower than the polymerization voltage.

Nafion membrane was modified with polyaniline by electrochemical methods, including constant current, constant potential and potential cycling. The methanol permeability and the proton conductivity of the Nafion membranes with and without modification were determined by the electrochemical oxidation of the permeated methanol and electrochemical impedance spectroscopy, respectively. It is found from FTIR results that the polyaniline formed by electrochemical method is in emeraldine state. With the modification of polyaniline, the methanol permeability of the Nafion membrane is reduced by one decade but there is only a slight decrease in proton conductivity. The power density output of direct methanol fuel cell using polyaniline-modified Nafion membrane is 40% larger than that using pure Nafion membrane. The modification with polyaniline is better than that with polypyrrole. The methanol permeability of the polyaniline-modified Nafion is about half of that of the polypyrrole-modified Nafion but the proton conductivity of the former is higher than the later.

Four commercial carbon materials, carbon nanotube, active carbon, acetylene black, and graphite, were treated by concentrated nitric acid. The surface properties and the electrochemical capacitance of the treated and the untreated carbon samples were studied by using scanning electron spectroscopy, BET surface analysis, constant current charge/discharge test, cyclic voltammetry, and alternative current impedance. It is found that the untreated samples have different specific capacitance and specific surface area, which are in the order from large to small: carbon nanotube, active carbon, acetylene black, and graphite. After treated with nitric acid, the specific surface area of these commercial carbon materials increases to different extents, and the specific capacitance of carbon nanotube, acetylene black and graphite increases proportionally to their specific surface area but the specific capacitance of active carbon decreases. The effect of acid treatment on the capacitance of the commercial carbon samples is related to their porosity structure and surface functional groups.

A copolymer, polyacrylonitrile–methyl methacrylate P(AN–MMA), was synthesized by suspension polymerization with acrylonitrile (AN) and methyl methacrylate (MMA) as monomers. With this copolymer, polymer membrane was prepared by phase inversion. The performances of the polymer were characterized by FTIR, SEM, DSC/TG, EIS and LSV. The copolymer contains CH2, CN and CO bonds, and shows its thermal stability up to 300 °C. The polymer membrane has a porous structure with an average pore diameter of 0.5 μm. The conductivity of the polymer electrolyte is 1.25 mS cm−1 at room temperature, and it is electrochemically stable up to 5 V (vs. Li). Using the polymer electrolyte as the gel polymer electrolyte (GPE), the cell Li/GPE/LiCoO2 shows its cyclic stability as good as the cell with liquid electrolyte.

The composite thin films of tin with 0 wt.%, 3.2 wt.%, 6.0 wt.%, and 11.8 wt.% graphite on the Cu foil were fabricated by magnetron sputtering (MS). The surface morphology, the composition and the electrochemical performance of the composite films were characterized by scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and galvanostatic charge/discharge (GC) measurements. It is found that the capacity loss of tin can be significantly reduced by its composite with graphite, but its discharge capacity decreases with increasing the content of graphite. The composite with 6.0 wt.% graphite show its good discharge capacity and cyclic stability. Its initial discharge capacity is 750 mAh g−1 and it keeps 85% of its initial discharge capacity after 10 cycles, comparing to the 14% for the pure tin.

Spinel lithium manganese oxides (LiMn2O4) modified with and without bismuth by sol–gel method were investigated by theoretical calculation and experimental techniques, including galvanostatic charge/discharge test (GC), cyclic voltammetry (CV), chronopotentiometry (CP), electrochemical impedance spectroscopy (EIS), inductively coupled plasma (ICP), powder X-ray diffraction (XRD), BET measurement, and infrared spectroscopy (IR). It is found that the performance of LiMn2O4 can be improved by the bismuth modification. The modified and the unmodified samples have almost the same initial discharge capacity, 118 and 120 mAh g−1, respectively. However, the modified sample has better cyclic stability than the unmodified sample. After 100 cycles, the capacity remains 100 and 89 mAh g−1 for the modified and the unmodified samples, respectively. Moreover, the results from EIS show that the modified sample has a quicker kinetic process for Li ion intercalation/de-intercalation than the unmodified one; the charge-transfer resistance of the former is less than one-sixth of that of the latter. After immersion in electrolyte (DMC:EC:EMC = 1:1:1, 1 mol L−1 LiPF6) for 10 h at room temperature, the modified sample has less change in open circuit potential, crystal volume, and vibration absorption of Mn–O bond, and has less dissolution of manganese into solution than the unmodified sample.

The voltammetric behaviors of graphite (GP) and its composites with carbon nanotube (CNT) were studied in 5 M H2SO4 + 1 M VOSO4 solution with cyclic voltammetry (CV), and the surface morphology of the composites was observed with scanning electron microscope (SEM). The results obtained from voltammetry show that the redox couples of V(IV)/V(V) and V(II)/V(III), as positive and negative electrodes of all vanadium flow liquid battery, respectively, have good reversibility but low current on the GP electrode, and the current can be improved by CNT. It is found from the observation of SEM that the CNT is dispersed evenly on the surface of sheet GP when they are mixed together. The best composition for the positive and the negative of all vanadium flow liquid battery determined by comparing voltammetric behavior of the composite electrodes with different content of CNT is 5:95 (wCNT/wGP) for both positive and negative electrodes. The activity of the composite electrode can be affected by the heat treatment of CNT. CNT treated at 200 °C gives better activity to the composite electrode.

Platinum–hydrogen tungsten bronze (Pt–HxWO3) was prepared on glass carbon electrode by potentiostat in 0.1 mM H2PtCl6 + 4 mM Na2WO4 + 2 M H2SO4. Its surface morphology, structure and activity toward oxygen reduction reaction were studied with scan electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy, and linear sweeping voltammetry. It is found that platinum and hydrogen tungsten bronze can be co-deposited together on glassy carbon and the activity of platinum toward oxygen reduction can be improved significantly by HxWO3. Furthermore, the activity of Pt–HxWO3 toward oxygen reduction is hardly influenced by methanol.

Copolymer, poly(acrylonitrile-co-methyl methacrylate) (P(AN-co-MMA)), was synthesized by solution polymerization with different mole ratios of monomers, acrylonitrile (AN) and methyl methacrylate (MMA). Polyethylene (PE) supported copolymer and gel polymer electrolyte (GPE) were prepared with this copolymer and their performances were characterized with FTIR, TGA, SEM, and electrochemical methods. It is found that the GPE using the PE-supported copolymer with AN to MMA = 4:1 (mole) exhibits an ionic conductivity of 2.06 × 10−3 S cm−1 at room temperature. The copolymer is stable up to 270 °C. The PE-supported copolymer shows a cross-linked porous structure and has 150 wt% of electrolyte uptake. The GPE is compatible with anode and cathode of lithium ion battery at high voltage and its electrochemical window is 5.5 V (vs. Li/Li+). With the application of the PE-supported GPE in lithium ion battery, the battery shows its good rate and initial discharge capacity and cyclic stability.

In this paper we reported a novel microbial fuel cell (MFC) based on Klebsiella pneumoniae (K. pneumoniae) strain L17 biofilm, which can utilize directly starch and glucose to generate electricity. The electrochemical activity of K. pneumoniae and the performance of the MFC were evaluated by cyclic voltammetry, scanning electron microscope (SEM) and polarization curve measurement. The results indicated that an established K. pneumoniae biofilm cells were responsible for the direct electron transfer from fuels to electrode during electricity production. The SEM observation proved the ability of K. pneumoniae to colonize on the electrode surface. This MFC generated power from the direct electrocatalysis by the K. pneumoniae strain L17 biofilm.

A tin film of 320 nm in thickness on Cu foil and its composite film with graphite of ∼50 nm in thickness on it were fabricated by magnetron sputtering. The surface morphology, composition, surface distributions of alloy elements, and lithium intercalation/de-intercalation behaviors of the fabricated films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe microanalyzer (EPMA), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma atomic emission spectrometry (ICP), cyclic voltammetry (CV), and galvanostatic charge/discharge (GC) measurements. It is found that the lithium intercalation/de-intercalation behavior of the Sn film can be significantly improved by its composite with graphite. With cycling, the discharge capacity of the Sn film without composite changes from 570 mAh/g of the 2nd cycle to 270 mAh/g of the 20th cycle, and its efficiency for the discharge and charge is between 90% and 95%. Nevertheless, the discharge capacity of the composite Sn/C film changes from 575 mAh/g of the 2nd cycle to 515 mAh/g of the 20th cycle, and its efficiency for the discharge and charge is between 95% and 100%. The performance improvement of tin by its composite with graphite is ascribed to the retardation of the bulk tin cracking from volume change during lithium intercalation and de-intercalation, which leads to the pulverization of tin.

The conversion behavior of soluble Pb(II) to deposited PbO2 on platinum in methanesulfonic acid solution was studied with voltammetry and compared with those on glassy carbon and lead oxides. The effects of methanesulfonic acid concentration and Pb(II) concentration, and temperature were considered. The conversion reaction of Pb(II) to PbO2 on platinum is irreversible and has a high overpotential, more than 300 mV. Low concentration of methanesulfonic acid, high concentration of Pb(II) and high temperature will favor the conversion reaction of Pb(II) to PbO2. The conversion reaction depends to a great extent on electrode materials. It is more difficult for the conversion reaction of Pb(II) to PbO2 to take place on glassy carbon than on platinum. However, the conversion reaction of Pb(II) to PbO2 becomes easy when it takes place on lead oxides, which was formed by reducing PbO2 under different potentials.

The insertion/removal processes of lithium ion in chromium doped spinel lithium manganese oxide (LiCrxMn2−xO4) were studied with electrochemical impedance spectroscopy (EIS) on a powder microelectrode, as well as X-ray diffraction (XRD) and cyclic voltammetry (CV), and was compared with those of pure spinel lithium manganese oxide (LiMn2O4). The insertion/removal process of lithium ion in the spinel oxides consists of three steps: charge transfer of lithium ion on the surface of the spinel oxides, diffusion and occupation of lithium ion in the lattice of the spinel oxide. The doping of chromium in spinel lithium manganese oxide results in the increase of the charge transfer resistance and the double layer capacitance for lithium insertion or removal and the decrease of the diffusion coefficient of lithium ion in the lattice of spinel oxide. However, the insertion capacitance, a parameter reflecting the occupation of lithium ion in the lattice of the spinel oxide, is hardly influenced by the doping of chromium. The influence of the doped chromium on the kinetic process of lithium insertion/removal in spinel lithium manganese oxide is related to the contraction of spinel lattice due to the doping.

The electrochemical behavior of propylene carbonate (PC)-based electrolytes with and without butyl sultone (BS) on graphite electrode and the performance of lithium ion batteries with these electrolytes were studied with cyclic voltammetry (CV), energy dispersive spectroscopy (EDS), as well as density functional theory (DFT) calculation. It is found that the co-insertion of PC with lithium ions into graphite electrode can be inhibited to a great extent by adjusting the composition of solvent in electrolytes. With the application of PC in the electrolyte without any additive, the discharge capacity of lithium ion battery is improved under high temperature or low temperature, however it decays under room temperature compared with the battery without PC. This drawback can be overcome by using BS as a solid electrolyte interphase (SEI) forming additive. BS has a lower LUMO energy and can be more easily electro-reduced than other components of solvent in electrolyte on a graphite electrode, forming a stable SEI film. With the application of BS in the electrolyte, the discharge capacity and cyclic stability of lithium ion battery is improved significantly under room temperature.

A group of valve-regulated lead–acid (VRLA) batteries (12 V, 33 Ah) cycled under high power has exhibited premature failure. The only difference between failed and healthy batteries is the shedding of active material from the positive plates. The dislodged material has been examined by means of X-ray diffraction, scanning electron microscopy, and cyclic voltammetry. It is found that the material has a β-PbO2 structure. The particles, which are oval in shape with a diameter of about 100 μm, are uniform and well separated from each other. The activity of the material can be restored under pressure. It is concluded that the failure mode of VRLA batteries under high-power cycling is softening of the positive active-material, which eventually results in deterioration of the electrical conductivity and de-activation of the material.

The pitting initiation and the pitting propagation of a hypoeutectoid iron-based alloy with inclusions of martensite in nitrite solutions containing chloride ions were studied by various electrochemical techniques. It was shown, by scanning reference electrode technique (SRET), that pitting occurred only on the martensite phase rather than hypoeutectoid areas. Anodic polarization behaviors of martensite electrode in nitrite solution with and without chloride ions are similar to those of hypoeutectoid electrode: both of martensite and hypoeutectoid electrodes were passive and the passive films could be broken by chloride ion. However, the open circuit potential of martensite electrode is more negative than that of hypoeutectoid electrode, and the passive current density of martensite electrode in the solution containing chloride ions was larger than that of hypoeutectod electrode. It was shown, by Mott-Schottky analysis, that the passive film of martensite electrode in the solution containing chloride ions had a higher donor concentration than that of hypoeutectoid electrode. There was a galvanic interaction between martensite and hypoeutectoid electrodes and it was this interaction that induced and accelerated the pitting corrosion on martensite area. Current and potential fluctuations, which reflected pitting initiation, were observed when martensite and hypoeutectoid electrodes were coupled together.

A comparison of uniformity of passive films formed on ferrite and martensite by three kinds of inorganic inhibitors, chromate, bicarbonate and nitrite, has been made by anodic polarization curve and AC impedance measurements. It was found, by anodic polarization curve analyses, that there was different pitting susceptibility of passive films formed on ferrite and martensite by chromate or bicarbonate. In the solution containing chloride ions, the broken potential of the passive film formed on ferrite by chromate or bicarbonate was more negative than that on martensite. However, the passive films formed on both ferrite and martensite by nitrite had similar pitting susceptibility. Their broken potentials were almost the same. The difference in pitting susceptibility of the passive films was explained by Mott–Schottky analyses. It was found that the passive film formed on ferrite by chromate or bicarbonate had a higher donor concentration than the passive film on martensite. The passive films with higher donor concentrations were more sensitive to chloride ions. However, the passive films formed on both ferrite and martensite by nitrite had the same donor concentration. A uniform passive film can be formed on a martensite mild steel with ferrite bands by nitrite.

•Series of polymer separators doping 10 wt.% to 200 wt.% of CeO2 were prepared.•Polymer contributes its high ionic conductivity to corresponding separator.•Nano-CeO2 dedicates its better thermal stability to the separators.•High voltage cathode using prepared separator has better cyclic and rate stability.•By considering performance and cost, proper amount of CeO2 in separator is 100 wt.%.Currently, the suitable proportion of inorganic particles in the ceramic separator has not been reported yet, due to the contradictory about the content of nano-particles in research papers (10 wt.%) and commercial application (large amount) [1,2]. In this paper, the nano-CeO2 contents on the properties of polyethylene (PE)-supported separator coating with poly (methyl methacrylate-butyl acrylate-acrylonitrile-styrene) (P(MMA-BA-AN-St)) copolymer is investigated systematically used in high voltage batteries for the first time. Since the copolymer contributes to high electrolyte uptake, and nano-CeO2 dedicates dimensional stability, the separator with 10 wt.% nano-CeO2 shows the highest ionic conductivity (2.5 × 10−3 S cm−1) at room temperature and the maximal electrolyte uptake (81.0 g m−2), while the separator with 100 wt.% nano-CeO2 exhibits better mechanical strength (52 MPa) and smaller shrinkage percentage (36%). Successively, cyclic performance of Li/LiNi0.5Mn1.5O4 cells indicates that the capacity retention of the cell using separator with 100 wt.% nano-CeO2 (72%) is second only to that with 10 wt.% nano-CeO2 (74%) after 200 cycles at 0.2 C between 3 V and 5 V, far larger than that without doping nano-CeO2 (51%) and PE (40%). By the consideration both of comprehensive performances and economic cost, 100 wt.% content is regarded as the most suitable appending proportion.

A novel composite, porous cubic Mn2O3@TiO2, was fabricated via a simple and cost-effective approach and characterized in terms of structure and performance as an anode for lithium ion batteries. The porous Mn2O3 cubes were developed by calcining cubic MnCO3 particles without using any template and then coated with TiO2 from heat decomposition of tetrabutyl titanate. The characterization from FESEM, TEM, HRTEM, XPS, BET, and XRD indicates that the as-fabricated Mn2O3@TiO2 takes a hierarchically porous cubic morphology with an edge of ∼340 nm and a core–shell structure with porous cubic Mn2O3 as the core, which consists of nanoparticles of ∼30 nm, and a layer of porous single-crystalline spinel TiO2 as the shell, which consists of smaller nanoparticles of ∼5 nm. The charge–discharge tests demonstrate that this unique configuration endows the as-fabricated Mn2O3@TiO2 with superior charge–discharge performance, to be specific, a rate capacity of 263 mA h g−1 at 6000 mA g−1 compared to the 9.7 mA h g−1 of Mn2O3, and a cyclic capacity of 936 mA h g−1 after 100 cycles at 200 mA g−1 compared to the 443 mA h g−1 of Mn2O3. The nanosized particles of Mn2O3 and TiO2 and the hierarchically porous structure among them provide paths for lithium-ion diffusion and sites for lithium-ion intercalation/deintercalation, while the chemically and mechanically stable TiO2 ensures the structural stability of Mn2O3 cubes, yielding excellent rate capability and cyclic stability of the as-fabricated Mn2O3@TiO2 as an anode for lithium ion batteries.

We report a composite (CG-S@PANI), sulfur (S) loaded in curved graphene (CG) and coated with conductive polyaniline (PANI), as a cathode for lithium–sulfur batteries. CG is prepared by splitting multi-wall carbon nanotubes and loaded with S via chemical deposition and then coated with polyaniline via in situ polymerization under the control of ascorbic acid. The physical and electrochemical performances of the resulting CG-S@PANI are investigated by nitrogen adsorption–desorption isotherms, X-ray powder diffraction, thermogravimetric analysis, transmission electron microscopy, electrochemical impedance spectroscopy, charge–discharge tests, and electronic conductivity measurements. CG-S@PANI as a cathode for lithium–sulfur batteries delivers an initial discharge capacity of 851 mA h g−1 (616 mA h g−1 on the basis of the cathode mass) at 0.2 C with a capacity retention of over 90% after 100 cycles. This nature is attributed to the co-contribution of CG and conductive PANI to the concurrent improvement in electronic conductivity and chemical stability of the sulfur cathode.

Oxidation-induced decomposition reactions of the representative complexes of propylene carbonate (PC)-based electrolytes were investigated using density functional theory (DFT) and a composite G4MP2 method. The cluster-continuum approach was used, where the oxidized PCn cluster was surrounded by the implicit solvent modeled via a polarized continuum model (PCM). The oxidative stability of the PCn (n = 2, 3, and 4) complexes was found to be around 5.4–5.5 V vs. Li+/Li, which is not only lower than the stability of an isolated PC but also lower than the stability of the PC–PF6−, PC–BF4− or PC–ClO4− complexes surrounded by the implicit solvent. The oxidation-induced decomposition reactions were studied. The decomposition products of the oxidized PC2 contained CO2, acetone, propanal, propene, and carboxylic acid in agreement with the previous experimental studies.

We report a novel synthesis of spinel LiNi0.5Mn1.5O4, in which cubic and porous Mn2O3 nanoparticles, obtained from cubic MnCO3, are used as templates to induce the formation of crystallographic facet- and size-defined spinel. This is done to accomplish excellent cyclic stability of the spinel as a cathode of a high voltage lithium ion battery. The uniformly dispersed pores in the template, whose size can be controlled by limiting the annealing time of MnCO3, facilitate the incorporation of lithium and nickel ions and ensure the formation of spinel with a predominant (111) facet, while the spinel inherits the particle size of the template under controlled temperatures. The characterizations from SEM, TEM and XRD confirm the structure and morphology of the precursors and the resulting product. The charge–discharge test demonstrates the excellent cyclic stability of the resulting products, especially at elevated temperatures: capacity retention of 78.1% after 3000 cycles with 10 C rate at room temperature and that of 83.2% after 500 cycles with 5 C rate at 55 °C.

An attempt has been carried out here to use nanoconic TiO2 hollow spheres as buffers to accommodate the volume expansion of high-capacity materials. Based on the TiO2 hollow spheres, we tailor-designed a novel composite, in which the high Li+-transport dynamics of titanate hollow spheres (TiO2) and the high capacity of tin oxide (SnO2) were intimately integrated into a hierarchical architecture of nanocones, while the unique spatial arrangement of the SnO2 component in the nano-cavities effectively accommodates the volume change during lithiation/de-lithiation, hence rendering the composite stable cycling life. Electrochemical tests revealed favorable performances of the composite SnO2–TiO2 nanocones in terms of enhanced lithium storage capacity, stable cycle life and improved rate performance compared with each material components.

Porous LiMn2O4 was fabricated with cubic MnCO3 as precursor and characterized in terms of structure and performance as the cathode of a lithium ion battery. The characterizations from SEM, TEM and XRD demonstrate that the fabricated product has a cubic morphology with an average edge of 250 nm, which it inherits from the precursor, and a porous structure architectured with single-crystalline spinel nanoparticles of 50 nm, which imitates the Mn2O3 that results from the thermal decomposition of the precursor. The charge–discharge tests show that the synthesized product exhibits excellent rate capability and cyclic stability: delivering a reversible discharge capacity of 108 mA h g−1 at a 30 C rate and yielding a capacity retention of over 81% at a rate of 10 C after 4000 cycles. The superior performance of the synthesized product is attributed to its special structure: porous secondary cube particles consisting of primary single-crystalline nanoparticles. The nanoparticle reduces the path of Li ion diffusion and increases the reaction sites for lithium insertion/extraction, the pores provide room to buffer the volume changes during charge–discharge and the single crystalline nanoparticle endows the spinel with the best stability.

In this paper, we report a successful synthesis of porous ZnCo2O4 nanoflakes by a morphology-conserved and pyrolysis-induced transformation of novel hexagonally shaped, highly ordered, and inorganic–organic–inorganic layered hybrid nanodisks. It is shown that the hexagonal hybrid nanodisks are constructed from organic molecule (ethylene glycol)-directed assembly of inorganic bilayers. The assembly mechanism has been established by a number of structural and spectroscopic techniques. The porous ZnCo2O4 nanoflakes have also been tested as a lithium ion battery electrode, showing high capacity and high cyclability.

In this study, polyvinyl alcohol (PVA) is proposed as a new binder to improve the power output of a microbial fuel cell. The physical and chemical properties of PVA are characterized with Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), contact angle testing, density functional theory calculations, and scanning electron microscopy (SEM). The electrochemical performance of an anode using carbon nanotubes as an electrocatalyst and PVA as a binder are evaluated in an Escherichia coli based fuel cell using chronoamperometry, electrochemical impedance spectroscopy (EIS), and polarization curve measurements, and a comparison is made with the conventional binder, polytetrafluoroethylene (PTFE). It is found that PVA is more hydrophilic and has stronger interactions with the bacterial membrane than PTFE. Accordingly, the anode with PVA as a binder facilitates the formation of biofilms and thus exhibits improved electron transfer kinetics between bacteria and the anode of the microbial fuel cell compared to the anode using PTFE. The MFC using PVA produces the largest maximum output power, 1.631 W m−2, which is 97.9% greater than the largest one produced by the MFC using PTFE (0.824 W m−2).

To improve the cyclability of a LiMn2O4/graphite lithium ion battery at elevated temperature, a carbonate-based electrolyte using prop-1-ene-1,3-sultone (PES) as additive was developed. The cycling performance of the LiMn2O4/graphite cell, based on the developed electrolyte at 60 °C, was evaluated by a constant current charge/discharge test, with comparison of the electrolyte using vinylene carbonate (VC) as additive. It was found that the cell based on the developed electrolyte exhibits better cyclability and exhibits better dimensional stability at elevated temperatures. The capacity retention is 91% and the swell value in thickness is 3.4% for the cell with PES after 150 cycles at 60 °C, while the respective values were 68% and 36.4% for the cell without additive, and 82% and 9.1% for the cell with VC. The results obtained from scanning electron spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, thermal gravimetric analysis, and molecular energy level calculations show that PES favors the formation of a stable solid electrolyte interphase, not only on the anode but also on the cathode of the LiMn2O4/graphite battery, effectively preventing electrolyte decomposition.

In this paper, we report a novel structure of Mn2O3, the triple-shelled Mn2O3 hollow nanocube, as the anode material for high-energy lithium-ion batteries, synthesized through a programmed annealing treatment with cubic MnCO3 as precursor. This hierarchical structure is developed through the interaction between the contraction force from the decomposition of MnCO3 and the adhesion force from the formation of Mn2O3. The structure has been confirmed by characterization with XRD, FESEM, TEM, and HRTEM. The charge–discharge tests demonstrate that the resulting Mn2O3 exhibits excellent cycling stability and rate capability when evaluated as an anode material for lithium-ion batteries. It delivers a reversible capacity of 606 mA h g−1 at a current rate of 500 mA g−1 with a capacity retention of 88% and a remaining capacity of 350 mA h g−1 at 2000 mA g−1.