The lithium–sulfur battery is considered as a prospective candidate for a high-energy-storage system because of its high theoretical specific capacity and energy. However, the dissolution and shutter of polysulfides lead to low active material utilization and fast capacity fading. Electrospinning technology is employed to directly coat an interlayer composed of polyacrylonitrile (PAN) and nitrogen-doped carbon black (NC) fibers on the cathode. Benefiting from electrospinning technology, the PAN-NC fibers possess good electrolyte infiltration for fast lithium-ion transport and great flexibility for adhering on the cathode. The NC particles provide good affinity for polysufides and great conductivity. Thus, the polysulfides can be trapped on the cathode and reutilized well. As a result, the PAN-NC-coated sulfur cathode (PAN-NC@cathode) exhibits the initial discharge capacity of 1279 mAh g–1 and maintains the reversible capacity of 1030 mAh g–1 with capacity fading of 0.05% per cycle at 200 mA g–1 after 100 cycles. Adopting electrospinning to directly form fibers on the cathode shows a promising application.Keywords: cathode; electrospinning; fibers; interlayer; lithium−sulfur battery; nitrogen-doped carbon;

Co3O4 is emerging as a promising anode candidate for lithium ion batteries (LIBs) with high theoretical capacity (890 mAh g–1) but suffers from poor electrochemical cycling stability resulting from the inferior intrinsic electronic conductivity and large volume changes during electrochemical cycling. Here, a new electrophoretic deposition Co3O4/graphene (EPD Co3O4/G) hybrid electrode is developed to improve the electrochemical performance. Through EPD, Co3O4 nanocubes can be homogeneously embedded between graphene sheets to form a sandwich-like structure. Owing to the excellent flexibility of graphene and a large number of voids in this sandwich-like structure, the structural integrity and unobstructed conductive network can be maintained during cycling. Moreover, the electrode kinetics has proved to be a fast surface-controlled lithium storage process. As a result, the Co3O4/G hybrid electrode exhibits high specific capacity and excellent electrochemical cycling performance. The Co3O4/G hybrid electrode was also further studied by in situ electrochemical XRD to understand the relationship of its structure and performance: (1) The observed LixCo3O4 indicates an intermediate of possible small volume change in the first discharging. (2) The theoretical capacity achievement of the Co3O4 in hybrid electrode was evidenced. (3) The correlation between the electrochemical performance and the structural evolution of the Co3O4/G hybrid electrode was discussed detailedly.Keywords: binder-free anode; Co3O4; electrophoretic deposition; graphene; in situ electrochemical XRD; lithium ion battery;

The Li3VO4@C microsphere composite was first reported as a novel cathode material for rechargeable aluminum-ion batteries (AIBs), which manifests the initial discharge capacity of 137 mAh g–1 and and remains at 48 mAh g–1 after 100 cycles with almost 100% Coulombic efficiency. The detailed intercalation mechanism of Al into the orthorhombic Li3VO4 is investigated by ex situ X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) of Li3VO4@C electrodes and the nuclear magnetic resonance aluminum spectroscopy (27Al NMR) of ionic liquid electrolytes in different discharge/charge states. First-principle calculations are also carried out to investigate the structural change as Al inserts into the framework of Li3VO4. It is revealed that the Al/Li3VO4@C battery goes through electrochemical dissolution and deposition of metallic aluminum in the anode, as well as the insertion and deinsertion of Al3+ cations in the cathode in the meantime. The rechargeable AIBs fabricated in this work are of low cost and high safety, which may make a step forward in the development of novel cathode materials based on the acidic ionic liquid electrolyte system.Keywords: aluminum-ion battery; cathode; ionic liquid; Li3VO4@C; mechanism;

AbstractA binder-free nest-like structured MnOx@carbon nanotubes anode for lithium-ion batteries (LIBs) was prepared through a facile electrophoretic deposition (EPD) method. Through the EPD process, both MnO2 nanowires and carbon nanotubes (CNTs), as starting materials, were interwoven tightly to form a uniform co-deposited film, possessing a nest-like architecture. After annealing the film under an inert atmosphere, the MnO2 nanowires transformed into Mn3O4 and MnO, as confirmed by the X-ray diffraction patterns. The nest-like electrode formed a porous and integrated conductive framework and provided the buffer space for the volume change of manganese oxides during cycling processes. As a result, this MnOx@CNTs electrode exhibited excellent cycling performance with a reversible capacity of 1152.1 mAh g−1 at 0.2 A g−1 and a superior cycling stability with 88.0 % capacity retention at 1 A g−1 after 200 cycles.

In this work, CuS microspheres are synthesized by a facile microwave synthesis without any template or additive. As-prepared CuS microspheres display steady reversibility by adopting triethylene glycol dimethyl ether (TEGDME) as the electrolyte solvent and adjusting cut-off voltage to 0.6 − 3.0 V. The discharge capacity stands at 162 mAh g−1 after 200 cycles with the capacity retention of 95.8%. Electrochemical kinetics of CuS electrodes is investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT) tests. Beyond that, electrochemical reactions of CuS electrodes are explored using ex-situ X-ray diffraction (XRD). As far as we know, it is not only the best performance of CuS electrodes in Na-ion batteries (NIBs) but also the first time that the kinetics and reaction mechanism of CuS in NIBs are investigated.

•Pt skin coated hollow Ag-Pt nanoparticle was prepared by a non-heating route.•This Ag/Pt catalyst shows excellent ORR catalytic performances.•The hollow structure raises the Pt utilization and thus the catalytic activity.•The experimental results can be well supported by the DFT calculation results.The catalytic activity and stability of electrocatalyst is critical for the commercialization of fuel cells, and recent reports reveal the great potential of the hollow structures with Pt skin coat for developing high-powered electrocatalysts due to their highly efficient utilization of the Pt atoms. Here, we provide a novel strategy to prepare the Pt skin coated hollow Ag-Pt structure (Ag-Pt@Pt) of ∼8 nm size at room temperature. As loaded on the graphene, the Ag-Pt@Pt exhibits a remarkable mass activity of 0.864 A/mgPt (at 0.9 V, vs. reversible hydrogen electrode (RHE)) towards oxygen reduction reaction (ORR), which is 5.30 times of the commercial Pt/C catalyst, and the Ag-Pt@Pt also shows a better stability during the ORR catalytic process. The mechanism of this significant enhancement can be attributed to the higher Pt utilization and the unique Pt on Ag-Pt surface structure, which is confirmed by the density functional theory (DFT) calculations and other characterization methods. In conclusion, this original work offers a low-cost and environment-friendly method to prepare a high active electrocatalyst with cheaper price, and this work also discloses the correlation between surface structures and ORR catalytic activity for the hollow structures with Pt skin coat, which can be instructive for designing novel advanced electrocatalysts for fuel cells.Download high-res image (249KB)Download full-size image

•NCM622 stored in high-temperature and high-humidity was deteriorated in structure.•A delithiation layer at the near-surface region was formed after storage.•The adsorbed species contributed a large proportion in electrochemical degradation.•The heat-treating process under oxygen flow can recover the stored degraded material.The high-temperature and high-humidity storage behaviors and electrochemical degradation mechanism of LiNi0.6Co0.2Mn0.2O2 cathode material are investigated systematically. After stored at 55 °C and 80% relative humidity, three kinds of changes are observed compared to the fresh materials. The first change is adsorbed species on the surface of the materials caused by atmospheric H2O and CO2. The second is a layer of impurities consisting of LiOH and Li2CO3 coated on the surface of the materials non-uniformly. The third is a delithiation layer directly contacting with the bulk materials in the near-surface region, which is believed to be formed by lithium-ions migrating out from the lattice accompanied by the generation of the impurities. A different combination of heating temperature, heating time and heating atmosphere is performed to achieve the separation of the adsorbed species and the delithiation layer (together with the impurities) and study the role of different part in electrochemical degradation, respectively. For the first and the following cycles, the effect of the adsorbed species on the electrochemical properties takes a larger proportion than that of the delithiation layer and impurities.

•The high sulfur content SCNT-PEG-NNH composite is obtained by a facile method.•The SCNT-PEG-NNH composite exhibits great cycling stability.•The SCNT-PEG-NNH composite supply a 3D conductive network during cycle.•The PEG and NNH are critical for inhibition of the polysulfide.Lithium sulfur batteries have been widely studied because of their high energy density. However, their commercialization has been impeded by several problems, such as the poor conductivity of the active material sulfur and its discharge products, the volume expansion and the shuttle effect caused by the polysulfide intermediates dissolving in organic electrolytes. To address these problems well, we have constructed high sulfur content spherical sulfur-carbon nanotube-polyethylene glycol-nickel nitrate hydroxide (SCNT-PEG-NNH) composite material by using a simple ball-milling method. The conductivity of the composite material gets improvement due to the spherical conductive frame constructed by CNT, while the shuttle effect of polysulfides is well inhibited by the wrapping of the PEG and the fixation of NNH. The results of electrochemical tests have shown that the performance of cathode made by the SCNT-PEG-NNH composite material is greatly improved. Therefore, the SCNT-PEG-NNH composite material can be a promising cathode material for lithium sulfur batteries.Download high-res image (193KB)Download full-size image

•CuS/graphene composite is synthesized via one-pot microwave-assisted method.•CuS/graphene composite shows enhanced cycle stability and rate performance.•The incorporation of graphene plays a vital role in the electrode.•The kinetic mechanisms are investigated by EIS, CV and GITT methods.In this work, CuS/graphene (CuS-G) composite is synthesized via one-pot microwave irradiation method under ambient conditions. As anode material for lithium ion batteries, the CuS-G composite delivers a significantly enhanced reversible capacity and charge/discharge cycle stability compared with pristine CuS. A capacity of 348 mAh g−1 can be maintained after 1000 cycles at the current density of 2.0 A g−1. Electrochemical impedance spectroscopy (EIS) along with cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT) measurements indicate that the incorporation of graphene sheets reduces the contact resistance and enhances lithium ion transfer rate during the electrochemical lithium insertion/extraction remarkably. Thus, as-prepared CuS spheres can be a promising anode material for high performance lithium ion batteries.Download high-res image (92KB)Download full-size image

Micro/nanostructured Co9S8 cubes and spheres (S-Co9S8) were successfully prepared with Co3O4 as templates via the vapor-based anion exchange reaction. The morphology and structure of both materials were characterized by SEM and XRD. Co9S8 microcubes and microspheres were composed of nanoparticles, inheriting the micro/nanostructure of Co3O4 precursors. Tested in lithium ion batteries, C-Co9S8 and S-Co9S8 anodes exhibited high specific capacities, excellent cycle stability (C-Co9S8: 369 mAh g−1, S-Co9S8: 370 mAh g−1 over 300 cycles at 1C) and high rate performances (C-Co9S8: 450 mAh g−1, S-Co9S8: ∼430 mAh g−1 at 5C).

•Li3VO4/C/rGO ternary composite with honeycomb-like structure is prepared by taking advantage of spray drying method and polystyrene (PS) soft template.•Li3VO4/C/rGO composite electrode possesses rapid Li+ ions intercalation kinetics and good structure integrity.•Li3VO4/C/rGO composite exhibits outstanding high-rate performance and long cycle-life (the high reversible capacity of 312 mAh g−1 can be maintained after 1000 cycles at 10C).Li3VO4/C/rGO (HC-LVO/C/G) ternary composite with honeycomb-like structure is successfully prepared through a simple spray drying method with polystyrene (PS) microspheres as soft template. In this characteristic structure, carbon-coated Li3VO4 nanoparticles are well wrapped by rGO sheets and uniformly distributed within the honeycomb-like micrometer-sized clusters. The double coating layers of amorphous carbon and rGO can avoid the direct exposure of Li3VO4 nanoparticles to the electrolyte and enhance the electronic conductivity. Meanwhile, the honeycomb-like structure can shorten the diffusion paths of Li+ ions and favors the relaxation of the strain/stress during cycling. The resultant HC-LVO/C/G composite exhibits significantly improved high-rate performance and long cycle-life (the high reversible capacity of 312 mAh g−1 can be maintained after 1000 cycles at 10 C) compared with the contrastive Li3VO4/C composite synthesized by a typical solid-state reaction method.Download high-res image (171KB)Download full-size image

Nanostructure construction and surface modification are effective ways to improve the electrochemical performances of electrode materials, especially for the conversion reaction-based materials. In this study, one-dimensional carbon coating bamboo-like Cu2-xS nanorods have been delicately designed in a template-free method. The structure and morphology are well characterized via different instruments such as X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Tested in lithium batteries as the anode, the Cu2-xS@C electrode shows superior electrochemical performances to pristine Cu2-xS. At 1 and 2 C, the Cu2-xS@C nanorod electrode releases 309 and 277 mAh g−1 after 300 cycles. At high rates of 15 and 22 C, the electrode still exhibits 269 and 264 mAh g−1. The kinetics of electrodes are also investigated by means of cyclic voltammetry (CV) and galvanostatic intermittence titration (GITT) measurements, proving the enhanced electrochemical properties. Thus, the one-dimensional bamboo-like Cu2-xS voided nanorods can be a promising candidate for high-performance batteries.Download high-res image (251KB)Download full-size image

•LVO was developed as an insertion anode material for magnesium ion batteries.•The LVO/C delivered a high discharge capacity of 318 mAh  g−1 at 20 mA g−1.•The insertion of Mg2+ into LVO was proved by element mapping, ex-situ XRD and XPS results.Li3VO4 (LVO) is a promising insertion-type anode material for lithium ion batteries (LIBs) while its electrochemical performance in magnesium ion batteries (MIBs) is rarely reported. Here, mesoporous LVO/Carbon (LVO/C) hollow spheres are synthesized by a facile spray-drying method and their electrochemical performance as Mg2+ insertion-host material is investigated for the first time. Galvanostatic charge-discharge results of LVO/C show no obvious platform in the potential range of 0.5∼2.5 V vs. Mg2+/Mg. The LVO/C delivers a high discharge capacity of 318 mAh g−1 at first cycle and exhibits good cycle performance. The electrochemical intercalation process is proved by element mapping, ex-situ X-ray Powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. Our results show that LVO is a promising anode material for MIBs.Download high-res image (149KB)Download full-size image

Although lithium-sulfur batteries are considered as promising high-energy-storage system owing to their high energy density, developing effective materials to host sulfur species on the cathode is still challenging. Herein, an inexpensive and effective carbon precursor, catechol and polyamine is explored to fabricate nitrogen/oxygen dual-doped hollow carbon nanospheres (DHCSs) as sulfur hosts. The group containing nitrogen and oxygen can provide stronger chemisorption for lithium polysulfides than single-doped carbon matrix, which is confirmed by X-ray photoelectron spectroscopy analysis and the theoretical calculation. As a result, the designed sulfur/DHCSs cathode delivers a stable cycling performance remained 851 mAh g−1 discharge capacity at 0.2 C with ∼0.08% capacity decay per cycle after 200 cycles, revealing its great promise for energy storage application.Download high-res image (191KB)Download full-size image

We report an effective double current collector electrode. In this study, we achieve a high areal loading double current collector electrode with high areal capacity density and long cycle life. We also adjust the charging condition (constant capacity charging) which leads to long cycle life with almost no capacity fading.

Silicon-multi-walled carbon nanotubes-carbon (Si-MWNTS-C) microspheres have been fabricated through the ball milling and spray drying method followed by the carbonization process. The as-prepared composite microspheres are confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The specific capacity of the as-prepared microspherical composite as anode in lithium-ion batteries (LIBs) is about 1100 mAh g−1 at the current density of 0.2 A g−1 (based on the total weight of the composite). At the high current density of 6 A g−1, the Si-MWNTS-C microspheres exhibit reversible capacity of 415 mAh g−1. Through the ex situ SEM, we observed that the Si-MWNTS-C microspherical composite particles have no extinct change on the electrode surface except for the growth of the spherical particles after 100 cycles. The excellent electrochemical performance is ascribed to the synergistic effect between Si nanoparticles (Si NPs) and MWNTS-C microspheres. The as-prepared Si-MWNTS-C microspheres can effectively accommodate large volume changes and provide a 3D conductive network during the lithiation–delithiation processes.

The Prussian blue, as a potential adsorbent of polysulfides to suppress the dissolution and shuttle of polysulfides for lithium–sulfur batteries, has been studied in this work. Our results show that Prussian blue improves the electrochemical reaction kinetics during discharge/charge processes. More importantly, the cathode with Prussian blue exhibits better cycling stability and higher discharge capacity retention (722 mAh g–1 at 0.2 A g–1 after 100 cycles) than the one without Prussian blue (151 mAh g–1). These improvements of electrochemical performances are ascribed to the fact that Prussian blue is very effective in suppressing the dissolution of polysulfides into liquid electrolyte by chemical adsorption.Keywords: chemical adsorption; electrochemical performances; lithium−sulfur batteries; polysulfides; prussian blue;

•The LFP has the best thermal stability, follows by the LMO and then the L523.•As increasing the ratio of electrode quality to electrolyte, the total exothermic quantities of L523 and LMO turn large, while that of LFP decrease.•Coexisting with electrolyte at high temperature, the L532, LMO and LFP suffer evident structure changes.The thermal stabilities of delithiated LiNi0.5Co0.2Mn0.3O2 (L523), delithiated LiMn2O4 (LMO), and delithiated LiFePO4 (LFP) for lithium ion batteries with bare electrode, solvent and different concentration of electrolyte under delithiated state have been investigated by using differential scanning calorimetry (DSC) and ex X-ray diffraction (XRD). The LFP has the best thermal stability, follows by the LMO and then the L523. The existing of solvent facilitates the decomposition of materials. The addition of Li salt in solvent can further accelerate the thermal decomposition of LMO and LFP; but hold back the decomposition of L523 at some extent that although the total reaction heat grown by 297 J g−1, the first exothermic peak (ca. 279 °C) moves backwards comparing with L523 and solvent coexisting system (ca. 255.7 °C). As increasing the ratio of electrode material quality to electrolyte, the total exothermic quantity of L523 and LMO becomes large, meanwhile the unit mass exothermic quantity of the L523 varies with little dropping tendency, and that of the LMO decreases obviously. However, for the LFP, the total exothermic quantity decreases and the unit mass exothermic quantity decreases more obviously. Also, the XRD patterns of the three samples at ambient temperature and after 350 °C processing with existing of solvent or electrolyte suggest that the L532, LMO and LFP suffer evident structure changes since their pristine peaks become broader, weaker and splitting or disappearing at high temperature.

Mesoporous Li3VO4/C hollow spheres have been prepared by a facile drying method and subsequent heat treatment process. The unique structure of the composite offers a synergistic effect to facilitate the transport of Li+ ions and electrons and afford an anode with superior rate capability and cyclic stability.

Aiming to reduce the dosage of the noble metal Pt and improve the catalytic activity of the catalyst in fuel cells, hollow porous Ag–Pt alloy nanoparticles with Pt coating are prepared via a facile controlled galvanic replacement reaction. Ag is used as the substrate to build a hollow porous structure and alloyed with Pt to minimize the tensile effect of the Ag on the deposited Pt skin which would significantly lower the catalytic performance of the Ag–Pt bimetallic catalyst. This hollow porous Ag/Pt bimetallic catalyst exhibits a long catalytic durability and a mass activity of 0.438 A mgPt−1 at 0.9 V (vs. RHE) towards the oxygen reduction reaction (ORR), which is ca. 3 times higher than that of the commercial Pt/C catalyst. The significant enhancement over the state-of-the-art Pt catalysts can be attributed to (1) the high surface area of the nanoparticles, (2) the more suitable d-band center of the Pt skin deposited on the Ag–Pt alloy substrate, and (3) the high thermal stability of the Ag–Pt alloy. Therefore, this work provides a new strategy for designing high-performance catalysts with low cost. In addition, the synthetic chemistry involved can possibly be extended for fabricating versatile catalysts with a similar structure.

The layer-structured LiNi0.5Co0.2Mn0.3O2 (L523) with high specific capacity and the spinel LiMn2O4 (LMO) with excellent thermostability complement each other in a blended cathode for better heat stability and electrochemical performance. The delithiated LMO starts to react with electrolyte at 160–200 °C to cause structural instability, and the delithiated L523 generates massive heat when its temperature is raised above 275 °C with the electrolyte present, but we found that the blended cathode shows a remarkable improvement in thermal stability since the reaction at 160–200 °C between LMO and the electrolyte disappears, and the total heat generated from the reaction between L523 and the electrolyte is drastically reduced. The reaction between LMO and the electrolyte at 160–200 °C causes structural instability of LMO as a self-accelerating attack from HF. With L523 present, this reaction is eliminated because the H+ from HF and Li+ in L523 undergo exchange reaction to prevent further generation of HF. The presence of LMO, however, reduces the total heat generated by L523 reacting with the electrolyte at high temperature. This thermal synergy between LMO and L523 not only improves the thermal safety of the blended cathode but also preserves their structures for better electrochemical performance.Keywords: electrolyte; LiMn2O4; LiNi0.5Co0.2Mn0.3O2; self-accelerating; synergistic effect

Fe3O4 is regarded as an attractive anode material for lithium ion batteries (LIBs) due to its high theoretical capacity, natural abundance, and low cost. However, the poor cyclic performance resulting from the low conductivity and huge volume change during cycling impedes its application. Here we have developed a facile electrophoretic deposition route to fabricate the Fe3O4/CNTs (carbon nanotubes)/rGO (reduced graphene oxide) composite electrode, simultaneously achieving material synthesis and electrode assembling. Even without binders, the adhesion and mechanical firmness of the electrode are strong enough to be used for LIB anode. In this specific structure, Fe3O4 nanoparticles (NPs) interconnected by CNTs are sandwiched by rGO layers to form a robust network with good conductivity. The resulting Fe3O4/CNTs/rGO composite electrode exhibits much improved electrochemical performance (high reversible capacity of 540 mAh g–1 at a very high current density of 10 A g–1, and a remarkable capacity of 1080 mAh g–1 can be maintained after 450 cycles at 1 A g–1) compared with that of commercial Fe3O4 NPs electrode.Keywords: anode; carbon nanotubes; electrophoretic deposition; Fe3O4; lithium ion battery; reduced graphene oxide

•The good conductive SnO2 is used as the coating layer.•SnO2-coated cathode shows an improvement electrochemistry performance.•The improved material shows the minimum amounts of transition metal dissolution.•Ex-XRD patterns confirm that the improved material has a better layered structure.•The coating layer plays an effective role in protecting the electrode from etching.The manganese metal ions and other transition metal ions in lithium manganite cathode materials will be dissolved into the electrolyte during cycling and storage at charged state, leading to severe capacity fading. Herein, the SnO2-coated Li1.2Mn0.54Co0.13Ni0.13O2 cathode material is prepared successfully by a simple organic liquid-phase method. The data of inductive coupled plasma-atomic emission spectroscopy and ex-XRD suggest that the coating layer can effectively suppress the dissolution of metal ions, which maintains the stability of main structure. The value of the charge transfer impedance is 35.49 Ω cm2 for LLMO-Sn1 after 50 cycles, while the LLMO is 123.30 Ω cm2. The LLMO-Sn1 has the highest discharge capacity of 214.0 mAh·g−1 after 150 cycles in half cell and exhibits the capacity retention of 86.8% after 150 cycles in full-cell. The decomposition reaction peak of LLMO-Sn1 appears at 250.1 °C.

•A facile method is developed to fabricate Si/CNT/C composites.•PVA hydrogel is acted as both locking-up agent and carbon source in composites.•The Si/CNT/C composites exhibit excellent capacity retention.A novel polyvinyl alcohol (PVA) hydrogel method is developed to synthesize Si/CNT/C composites. The Si nanoparticles and CNTs are ‘position’ locked up by PVA hydrogel in a simple aqueous solution process, and then the Si-CNT-PVA hydrogel has pyrolyzed to form Si/CNT/C composites. In this unique structured Si/CNT/C composites, the CNTs form a porous network acting both as conductive agent for electron transfer and buffer space to accommodate huge Si volume change during lithiation/delithiation process, while the coating layer of carbon carbonized from polyvinyl alcohol (PVA) hydrogel is conducive to stabilize the interweaved composite structure. The complex structures of Si/CNT/C composites and their electrochemical properties are presented in this paper. The Si/CNT/C composites exhibit an initial reversible capacity of nearly 800 mAhg−1, an excellent capacity retention of 97.1% after 100 cycles at the rate of 0.1 C, and high capacity retention even at high current rate.

•Uniform cubic and spherical LiCoO2 were synthesized by a two-step method.•The large cubic and spherical LiCoO2 particles reduce the contact area and weaken the side reactions on interfaces between electrolyte and electrode.•Cubic and spherical LiCoO2 showed excellent performance in cyclic stability and rate capability.In this work, morphology-controlled lithium cobalt oxides (LCO) were obtained by a simple two-step method that involves a Co3O4 synthetic process, in which cubic and spherical Co3O4 were prepared by a hydrothermal method and a subsequent lithiation process with Li2CO3. The structures and morphologies of two materials were investigated by XRD, SEM and TEM. In contrast with the LCO prepared by using commercial Co3O4 precursor, the cubic and spherical LCO materials have an excellent performance in cyclic stability and rate capacity which is attributed to the better fluidity and less agglomeration with specific morphology of LCO materials.

A facile and efficient electrostatic-assembly method to fabricate ball-milling-silicon@carbon/reduced-graphene-oxide composite (bmSi@C/rGO) has been developed. In the fabrication process, chitosan (CTS), as a charged bridge, connected ball milling silicon (bmSi) and graphene oxide (GO), and then was transformed into carbon coating by heat treatment. The carbon coated ball milling silicon (bmSi@C) particles were distributed evenly between the sheets of reduced graphene oxide (rGO). Therefore, the carbon coating and the wrinkled graphene sheets formed a superior conductive matrix and a buffer zone. The composite used as anode material exhibited high reversible capacity of 935.77 mAh g−1 and 71.9% capacity retention after 100 cycles. The excellent electrochemical properties are attributed to the well-designed structure, in which both the carbon layer and the rGO play an important role for improving the whole electrical conductivity and preventing the silicon from pulverization.

•Surfaces coating with CoAl2O4 for LNMO improve its thermal stability distinctly.•The dissolution of transition metal of LNMO in electrolyte is alleviated, which keep the structure of electrode integrity.•The electrochemical performance of LNMO at high temperature is improved obviously after CoAl2O4 coating.Aluminum cobalt oxide-coated LiNi0.5Mn1.5O4 (LNMO) cathode materials are synthesized via a wet-coating method. The surface coating of the LNMO with cobalt aluminum oxide (CoAl2O4) does not alter its spinel structure, but greatly affects its thermostability. The complete, thin cobalt aluminum oxide coating layer strongly adheres to the host material and possesses a great thermal stability and electrochemical resistance, and it is not damaged in acid or alkali environments. The CoAl2O4 coating layer in this work successfully inhibits the dissolution of transition metal ions and maintain the stability of the LNMO structure. This CoAl2O4 coating layer also hold back the HF scavenger of the spinel structure in the electrolyte, which leads to enhanced electrochemical properties, especially at high temperatures. Furthermore, the coated LNMO exhibits an obviously improved thermostability compared with bare LNMO.

Nitrogen plasma processing technology is used to introduce nitrogen to the surface of Li1.2Mn0.52Co0.13Ni0.13O2. The material shows a better rate capability and cycle stability than pristine Li1.2Mn0.52Co0.13Ni0.13O2. Compared to the conventional treatment methods, it is a facile and promising way.

Both the high-voltage electrochemical performance improvement and the storage improvement of Ni-rich layer cathode materials have been investigated. The performance improvement is achieved by a surface modification, involving Li2MnO3 as the coating layer. Owing to the composite structure, the Ni-rich layer cathode material has a stable interface, resulting in the improvement of the high-voltage cycling performance (the initial discharge capacities of 202.5 mA h g−1 and the capacity retention of 86.4% over 50 cycles at 3.0–4.5 V vs. Li/Li+). The differential scanning calorimetry (DSC) measurements show that the improved material presents a much lower calorific value than the pristine material. The perfect electrochemical properties of the improved composite material are still maintained after the material has been exposed to air for 2 months. The Fourier-transform infrared (FT-IR) spectroscopic analysis indicates that the formation of Li2CO3 on the material surface is suppressed. Obviously, the as-improved composite material maintains stable features after high-voltage cycling and is much easier to be stored.

•We prepare the nanocomposites of CuxS microspheres wrapped with rGO.•As-prepared CuxS/rGO can effectively accommodate large volume changes.•As-prepared CuxS/rGO supply a 2D conductive network.•As-prepared CuxS/rGO trap the polysulfides generated during the discharge–charge.•The CuxS/rGO has high capacity, cycle stability and excellent rate capability.In this study, a facile two-step approach was developed to prepare the nanocomposites (CuxS/rGO) of copper sulfide (CuxS) microspheres wrapped with reduced graphene oxide (rGO). The morphology and structure of CuxS/rGO materials were researched by using SEM, XRD and laser Raman spectroscopy. As-prepared CuxS/rGO nanocomposites, as an active anode material in LIBs, showed distinctly improved electrochemical characteristics, superior cycling stability and high rate capability. Due to the synergistic effect between the CuxS microspheres and the rGO nanosheets, as-prepared CuxS/rGO nanocomposites could effectively alleviate large volume changes, provide a 2D conductive network and trap the diffusion of polysulfides during the discharge–charge processes, therefore, the CuxS/rGO nanocomposites showed excellent electrochemical characteristics.

Lithium-rich manganese-based layered oxides with a composition of xLi2MnO3·(1 − x)LiMO2 (M = Mn, Co, Ni, etc.) are attractive, due to their high discharge capacity. However, the concerns over Li2MnO3–LiMO2 composite cathodes such as high irreversible capacity and poor rate performance remain to be the main obstacles to commercialization. Here we introduce a thin chromium oxide layer and a spinel metal oxide layer to doubly coat on the surface of Li1.2Mn0.52Ni0.13Co0.13O2 (LMNCO) by a spray drying process as well as an inducer of the layered@spinel@coating layer heterostructure to achieve better electrochemical performance. X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM) results confirm the successful formation of a chromium oxide layer on the surface of LMNCO without destroying its intrinsic structure. The reduced irreversible capacity loss and improved cycling stability are ascribed to the coating layer and the heterostructure. Furthermore, fast voltage fading of the solid solutions of layered transition metal oxides is also alleviated.

Micro-/nano-structured spherical intergrown LiMn2O4–LiNi0.5Mn1.5O4 (LMO–LNMO I, LiNi0.25Mn1.75O4) particles as a cathode material have been synthesized by an impregnation method with highly reactive chestnut-like MnO2 nano-spheres as a manganese source and structural template. The LMO–LNMO I consisted of aggregates of nano-sized particles with a well-defined cubic spinel structure. The electrochemical performance and thermostability of LMO–LNMO I are better than those of a simple mechanical mixture of LiMn2O4 and LiNi0.5Mn1.5O4 (LMO–LNMO M), and much better than those of individual LiMn2O4 and LiNi0.5Mn1.5O4 monomers. Within this special structure, LNMO acts as a skeleton to stabilize the structure of LMO and enables more lithium ions in LMO to participate in the charge–discharge process along with those in LNMO, leading to high specific discharge capacities. In addition, this material exhibits excellent cycle stabilities at room temperature (25 °C) as well as at elevated temperature. It presented a discharge capacity of 130 mA h g−1, with 96.2% capacity retention after 100 cycles at 25 °C at 1 C. When the temperature and rate are increased to 55 °C and 5 C, it still delivers a discharge capacity of 131 mA h g−1, with a capacity retention of 95% after 100 cycles. Being synthesized by a special impregnation method, LMO–LNMO I shows a more homogeneous ion mixing of Ni and Mn in the structure at the atomic level with a more enhanced thermostability due to its high Mn content compared to LNMO. The structural stability and high electrical conductivity of LMO–LNMO I are responsible for the excellent electrochemical performance and outstanding thermal stability.

A binder-free silicon (Si) based electrode for lithium-ion battery was fabricated in an organic solvent through one-step electrophoretic deposition (EPD). The nanosized Si and acetylene black (AB) particles were bonded tightly together to form a homogeneous co-deposited film with 3D porous structure through the EPD process. The 3D porous structure provides buffer spaces to alleviate the mechanical stress due to silicon volume change during the cycling and improves lithium-ion conductivity by shortening ion diffusion length and better ion conducting pathway. The electrode prepared with 5 s deposition duration shows the best cycling performance among electrodes fabricated by EPD method, and thus, it was selected to be compared with the silicon electrode prepared by the conventional method. Our results demonstrate that the Si nanoparticle electrode prepared through EPD exhibits smaller cycling capacity decay rate and better rate capability than the electrode prepared by the conventional method.Keywords: 3D porous structure; binder-free; electrophoretic deposition; lithium-ion battery; Si;

•Core–shell structured SiO2–poly(methyl methacrylate) sub-microspheres are prepared.•A functional ceramic-coated separator coated by the sub-microspheres is developed.•The separator exhibits good thermostability and electrolyte retention ability.•The separator multi-functionality provides cells with greater safety performance.To improve the safety of lithium-ion batteries (LIBs), a functional ceramic-coated separator (FCC separator) is developed by coating core–shell structured silica–poly(methyl methacrylate) (SiO2–PMMA) sub-microspheres on one side of a conventional porous polyethylene (PE) separator. The FCC separator possesses multi-functional properties of better separator thermostability and higher electrolyte stability by combining the advantages of both the ceramic-coated separator and the gel polymer electrolyte (GPE). The heat-resistant SiO2 core particles effectively protect the FCC separator from thermal shrinkage. Meanwhile, the PMMA shells form a gel after swelling and activation by the liquid electrolyte, which endows the FCC separator with the functional properties of the GPE to stabilize the electrolyte. As a result, the FCC separator shows considerable wettability for the liquid electrolyte and outstanding electrolyte retention ability at elevated temperature. Moreover, the FCC separator with the coating layer improves the safety performance of cells by preventing cells from experiencing internal short circuits at high temperature. Meanwhile, the cells assembled with such separators demonstrate superior cycle performance and C-rate capability. Therefore, the FCC separator provides LIBs with greater security and better electrochemical performance.

•Ceramic coating separator was developed with one-dimensional silica tubes (ST).•The ST coating separator exhibits better thermal stability.•The inorganic mesh network prevents the thermal shrinkage of the separator.•The coating method is introduction ceramics to one side of PE separator.In an endeavor to improve the thermal stability of lithium-ion batteries (LIBs), a new kind of ceramic coated separator has been developed based on introducing one-dimensional silica tubes (ST) to one side of a commercial polyethylene (PE) porous separator. The ST interpenetrating network diminishes the thermal-induced dimensional change of the commercial separator without compromising the cell performance. In particular, compared to spherical silica particle (SP) coated separator, the ST coated separator exhibits significantly enhanced thermal stability at elevated temperature. Furthermore the ST coated separator shows better mechanical performance as well as the improved electrolyte absorption and retention behavior, which provides a promising solution to replace conventional polymer separator for high-performance LIBs.

•Novel anion exchange membranes based on pyrrolidonium salts and PVA were prepared.•The properties of the membranes could be tuned by varying the blending ratios.•The membranes showed excellent thermal, chemical and dimensional stability.•The membranes displayed the high OH− conductivity of above 10−2 S cm−1 at 25 °C.•A peek power density of 88.9 mW cm−2 of the H2/air fuel cell was obtained at 65 °C.Novel anion-exchange membranes based on two kinds of pyrrolidonium type ionic liquids, N-methyl-N-vinyl-pyrrolidonium (NVMP) and N-ethyl-N-vinyl-pyrrolidonium (NVEP), have been synthesized via polymerization and crosslinking treatment, followed by membrane casting. The covalent cross-linked structures of these membranes are confirmed by FT-IR. The obtained membranes are also characterized in terms of water uptake, ion exchange capacity (IEC), ionic conductivity as well as thermal, dimensional and chemical stability. The membranes display hydroxide conductivity of above 10−2 S cm−1 at 25 °C. Excellent thermal stability with onset degradation temperature above 235 °C, good alkaline stability in 6 mol L−1 NaOH at 60 °C for 168 h and remarkable dimensional stability of the resulting membranes have been proved. H2/air single fuel cells employed membrane M3 and N3 show the open-circuit voltage (OCV) of 0.953 V and 0.933 V, and the maximum power density of 88.90 mW cm−2 and 81.90 mW cm−2 at the current density of 175 mA cm−2 and 200 mA cm−2 at 65 °C, respectively.

•Copper sulfides can be simply synthesized by heating a mixture of copper and sulfur powders in different stoichiometries.•The copper-excess copper sulfides electrodes show enhanced electrochemical performance.•The critical factor for CuxS electrodes achieving high performance is that the ratio of Cu and S is greater than 2.Copper sulfides are synthesized by heating a mixture of copper and sulfur powders in different stoichiometries in N-methyl-2-pyrrolidinone (NMP) solvent. All the electrodes show excellent electrochemical performance, especially ‘copper excess’ copper sulfides electrodes. These electrodes can be charged and discharged at high rate, with good capacity retention. The electrochemical reaction mechanism of copper sulfides during discharge–charge process is investigated. It is most likely that all of S element in the copper excess electrode would transfer into a crystal of Cu2S during charge–discharge cycles, which corresponded to a single electrochemical reaction and showed excellent cycling and rate performance. These encouraging results indicate that copper-excess copper sulfides could be a promising anode material for lithium batteries with high rate capability.

•Nonwoven PI as structural support and PE particles as coating layer.•PE–PI–S with a shutdown temperature range from 120 °C to more than 200 °C.•Battery with PE–PI–S shows stable cycling and good rate performance.In this paper, a composite membrane with nonwoven polyimide (PI) membrane as structural support and polyethylene (PE) particles coating layer as a thermal shutdown layer, is fabricated as the separator for lithium-ion battery. Different from PI nonwoven membrane, the PE coating PI nonwoven composite membrane (PE–PI–S) not only shows excellent thermal shutdown function, similar to traditional multilayer PP/PE/PP separator, but also exhibits much higher thermal stability, better wettability to the polar electrolyte and lower internal resistance than the PP/PE/PP separator. The electrolyte uptake and ionic conductivity of PE–PI–S increase from 58%, 0.84 mS cm−1 to 400%, 1.34 mS cm−1, respectively. Furthermore, the thermal shutdown function of PE–PI–S can be controlled widely in the temperature range from 120 °C to more than 200 °C while the multilayer PP/PE/PP separator only with a shutdown temperature range from 130 °C to 160 °C. Lithium ion battery with PE–PI–S nonwoven separator also shows excellent stable cycling and good rate performance.

This paper firstly reports a facile hydrothermal method to prepare CuFeS2 spike-like nanorods as a promising anode material for lithium ion batteries. When being evaluated as an anode material in traditional carbonate-based (EC/DEC/DMC) and ether-based (DOL/DME) electrolytes, it's found that the type of the electrolytes plays a key role in contribution to the electrochemical performance. The CuFeS2 binary mental sulfide material has initial discharge capacities of 632.6 mAh/g in the carbonate-based electrolyte and 674.9 mAh/g in the other at the rate of 0.2 C. After 50 circles, the discharge capacity decays severely, down to 64.3 mAh/g while the one performed in the ether-based electrolyte still possesses a capacity of 425.3 mAh/g, whose capacity retention is far more higher. Besides, an outstanding rate capability (∼190 mAh/g) can be obtained at a high rate of 10 C in the ether-based electrolyte, which is indicative of becoming promising anode materials for high-rate lithium batteries.

The Li2TiO3-coated LiNi0.5Co0.2Mn0.3O2 (LTO@NCM) cathode materials are synthesized via an in situ co-precipitation method followed by the lithiation process and thermal annealing. The Li2TiO3 coating layer is designed to strongly adhere to the core-material with 3D diffusion pathways for Li+ ions. Electrochemical tests suggest that compared with pristine NCM, Li2TiO3 serves as both a Li ion conductive layer and a protective coating layer against the attack of HF in the electrolyte, and remarkably improves the cycling performance at higher charged state and rate capability of the LTO@NCM composite material. What is more, phase transformation of NCM and dissolution of metal ions at high-temperatures at 4.6 V cutoff potential are effectively suppressed after LTO-coating. Our study demonstrates that LTO-coating on the surface of NCM is a viable method to improve the electrochemical performance of NCM, especially at high rates and under high-voltage charged conditions.

A new type of microsized porous spherical LiNi0.5Mn1.5O4 (LNMO-Air) cathode material for a lithium ion secondary battery has been synthesized by an impregnation method using highly reactive nanocupule MnO2 spheres as the manganese source. These LNMO-Air spheres are aggregates of nanosized polyhedron particles with well-defined cubic spinel structure. They showed excellent rate capability and cycle stability, compared with other microspheres of LNMO. We also investigated the effect of the trace amounts of Mn3+ in the crystal structure on its specific capacity and cycle stability. Compared with the sample (LNMO-O2) calcined in an oxygen atmosphere, which is considered to be Mn3+ free, LNMO-Air exhibits superior specific capacity, cycling ability and rate capability. Because of the presence of trace amounts of Mn3+, the LNMO-Air sample presents a discharge specific capacity of 108 mA h g−1 at 5 C rate at 55 °C after 80 cycles without significant reduction. These improvements can be explained by better ion conductivity as the metal oxide layer spacing is enlarged to facilitate faster ion transfer and significantly improved electrical conductivity; both are attributed to the presence of Mn3+.

A series of nitrogen-modified Li4Ti5O12 (N-LTO) nanomaterials with hierarchical micro/nanoporous structures are first synthesized via a facile one-step combustion process using thermal decomposition of urea. Successful deposition of a TiN thin layer onto the LTO surface was confirmed by transmission electron microscopy with energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, Raman spectroscopy, and thermogravimetric measurements. The electrochemical performances of the N-LTO nanomaterials are also investigated in this work. Compared with pristine LTO, the N-LTO nanomaterial with 1.1 wt % nitrogen exhibits a higher rate capability and better reversibility. At charge/discharge rates of 1, 2, 8, and 15 C, the discharge capacities of the N-LTO electrode were 159, 150, 128, and 108 mAh g–1, respectively. After 200 cycles at 1 C, its capacity retention was 98.5% with almost no capacity fading.Keywords: anode electrode; decomposition of urea; deposition of TiN; lithium battery;

The novel Na-substituted Li1-xNaxNi0.5Mn1.5O4 has been synthesized to use as a cathode material for lithium ion battery via a solid-state method. Both crystal domain size and lattice parameter are influenced by the doping content of Na, without changing the basic spinel structure. The doping of Na ions not only increase the disordered distribution of nickel and manganese cations in spinel, but also increase two additional electron hopping paths, which contribute to a better charge transfer ability, relieve the ohmic polarization and electrochemical polarization of materials and improve lithium ion diffusion coefficient. After Na-doped, the discharge specific capacity rises up comparing to the sample without Na-doped. As a result, the excellent rate capability is achieved for the doping content of 5% Na in spinel, that the discharge capacity is increased by 3.4%, 9.4%, 9.1%, 8.7%, 6.5% and 3.4% in comparison with LNMO, presenting a discharge specific capacity of 121, 119.4, 118.5, 115.1, 108.4 and 101.3mAh·g−1 at the rates of 0.2, 0.5, 1, 2, 5 and 10 C respectively, with tiny Mn3+ platform appearing. In addition, the sample presents a discharge capacity of 125mAh·g−1 at 1 C, with a retention of 116.2mAh g−1 after 100 cycles. Even cycling at 5 C rate and 55 °C, the cell with 5% Na-doped LNMO cathode can has 82% of capacity retention after 400 cycles, indicating that it is a promising cathode material for lithium ion batteries.

Lithium-sulfur battery has received extensive attention because of its high energy density, but its practical application has been limited by several problems such as short cycle life and low efficiency. In this study, we prepare monodispersed sulfur nanoparticles (S NPs) on partially reduced graphene oxide (S-prGO) during reduction of graphene oxide by spray method. The S-prGO composite is then recombined with polydopamine (PDA) to get the S-prGO-PDA composite. The S-prGO-PDA composite exhibits great cycling stability, coulombic efficiency and capacity retention. When charge-discharge at current density of 200 mA g−1, the specific capacity is 1122 mAh g−1 at the first discharge and 647 mAh g−1 after 100 cycles, with stable coulombic efficiency of 98%.

Retraction of ‘In situ nano-coating on Li1.2Mn0.52Ni0.13Co0.13O2 with a layered@spinel@coating layer heterostructure for lithium-ion batteries’ by Bing Li et al., J. Mater. Chem. A, 2015, 3, 21290–21297.

We report an effective double current collector electrode. In this study, we achieve a high areal loading double current collector electrode with high areal capacity density and long cycle life. We also adjust the charging condition (constant capacity charging) which leads to long cycle life with almost no capacity fading.

The Li2TiO3-coated LiNi0.5Co0.2Mn0.3O2 (LTO@NCM) cathode materials are synthesized via an in situ co-precipitation method followed by the lithiation process and thermal annealing. The Li2TiO3 coating layer is designed to strongly adhere to the core-material with 3D diffusion pathways for Li+ ions. Electrochemical tests suggest that compared with pristine NCM, Li2TiO3 serves as both a Li ion conductive layer and a protective coating layer against the attack of HF in the electrolyte, and remarkably improves the cycling performance at higher charged state and rate capability of the LTO@NCM composite material. What is more, phase transformation of NCM and dissolution of metal ions at high-temperatures at 4.6 V cutoff potential are effectively suppressed after LTO-coating. Our study demonstrates that LTO-coating on the surface of NCM is a viable method to improve the electrochemical performance of NCM, especially at high rates and under high-voltage charged conditions.

A new type of microsized porous spherical LiNi0.5Mn1.5O4 (LNMO-Air) cathode material for a lithium ion secondary battery has been synthesized by an impregnation method using highly reactive nanocupule MnO2 spheres as the manganese source. These LNMO-Air spheres are aggregates of nanosized polyhedron particles with well-defined cubic spinel structure. They showed excellent rate capability and cycle stability, compared with other microspheres of LNMO. We also investigated the effect of the trace amounts of Mn3+ in the crystal structure on its specific capacity and cycle stability. Compared with the sample (LNMO-O2) calcined in an oxygen atmosphere, which is considered to be Mn3+ free, LNMO-Air exhibits superior specific capacity, cycling ability and rate capability. Because of the presence of trace amounts of Mn3+, the LNMO-Air sample presents a discharge specific capacity of 108 mA h g−1 at 5 C rate at 55 °C after 80 cycles without significant reduction. These improvements can be explained by better ion conductivity as the metal oxide layer spacing is enlarged to facilitate faster ion transfer and significantly improved electrical conductivity; both are attributed to the presence of Mn3+.

Lithium-rich manganese-based layered oxides with a composition of xLi2MnO3·(1 − x)LiMO2 (M = Mn, Co, Ni, etc.) are attractive, due to their high discharge capacity. However, the concerns over Li2MnO3–LiMO2 composite cathodes such as high irreversible capacity and poor rate performance remain to be the main obstacles to commercialization. Here we introduce a thin chromium oxide layer and a spinel metal oxide layer to doubly coat on the surface of Li1.2Mn0.52Ni0.13Co0.13O2 (LMNCO) by a spray drying process as well as an inducer of the layered@spinel@coating layer heterostructure to achieve better electrochemical performance. X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM) results confirm the successful formation of a chromium oxide layer on the surface of LMNCO without destroying its intrinsic structure. The reduced irreversible capacity loss and improved cycling stability are ascribed to the coating layer and the heterostructure. Furthermore, fast voltage fading of the solid solutions of layered transition metal oxides is also alleviated.

Micro-/nano-structured spherical intergrown LiMn2O4–LiNi0.5Mn1.5O4 (LMO–LNMO I, LiNi0.25Mn1.75O4) particles as a cathode material have been synthesized by an impregnation method with highly reactive chestnut-like MnO2 nano-spheres as a manganese source and structural template. The LMO–LNMO I consisted of aggregates of nano-sized particles with a well-defined cubic spinel structure. The electrochemical performance and thermostability of LMO–LNMO I are better than those of a simple mechanical mixture of LiMn2O4 and LiNi0.5Mn1.5O4 (LMO–LNMO M), and much better than those of individual LiMn2O4 and LiNi0.5Mn1.5O4 monomers. Within this special structure, LNMO acts as a skeleton to stabilize the structure of LMO and enables more lithium ions in LMO to participate in the charge–discharge process along with those in LNMO, leading to high specific discharge capacities. In addition, this material exhibits excellent cycle stabilities at room temperature (25 °C) as well as at elevated temperature. It presented a discharge capacity of 130 mA h g−1, with 96.2% capacity retention after 100 cycles at 25 °C at 1 C. When the temperature and rate are increased to 55 °C and 5 C, it still delivers a discharge capacity of 131 mA h g−1, with a capacity retention of 95% after 100 cycles. Being synthesized by a special impregnation method, LMO–LNMO I shows a more homogeneous ion mixing of Ni and Mn in the structure at the atomic level with a more enhanced thermostability due to its high Mn content compared to LNMO. The structural stability and high electrical conductivity of LMO–LNMO I are responsible for the excellent electrochemical performance and outstanding thermal stability.

Aiming to reduce the dosage of the noble metal Pt and improve the catalytic activity of the catalyst in fuel cells, hollow porous Ag–Pt alloy nanoparticles with Pt coating are prepared via a facile controlled galvanic replacement reaction. Ag is used as the substrate to build a hollow porous structure and alloyed with Pt to minimize the tensile effect of the Ag on the deposited Pt skin which would significantly lower the catalytic performance of the Ag–Pt bimetallic catalyst. This hollow porous Ag/Pt bimetallic catalyst exhibits a long catalytic durability and a mass activity of 0.438 A mgPt−1 at 0.9 V (vs. RHE) towards the oxygen reduction reaction (ORR), which is ca. 3 times higher than that of the commercial Pt/C catalyst. The significant enhancement over the state-of-the-art Pt catalysts can be attributed to (1) the high surface area of the nanoparticles, (2) the more suitable d-band center of the Pt skin deposited on the Ag–Pt alloy substrate, and (3) the high thermal stability of the Ag–Pt alloy. Therefore, this work provides a new strategy for designing high-performance catalysts with low cost. In addition, the synthetic chemistry involved can possibly be extended for fabricating versatile catalysts with a similar structure.

Mesoporous Li3VO4/C hollow spheres have been prepared by a facile drying method and subsequent heat treatment process. The unique structure of the composite offers a synergistic effect to facilitate the transport of Li+ ions and electrons and afford an anode with superior rate capability and cyclic stability.