Because of the high theoretical capacity of 1675 mAh g–1 and high energy density of 2600 Wh kg–1, respectively, lithium–sulfur batteries are attracting intense interest. However, it remains an enormous challenge to realize high utilizations and loadings of sulfur in cathodes for the practical applications of Li–S batteries. Herein, we design a quasi-2D Co@N–C composite with honeycomb architecture as a multifunctional sulfur host via a simple sacrificial templates method. The cellular flake with large surface area and honeycomb architecture can encapsulate much more sulfur, leading to high sulfur content (HSC) composites, and by stacking these HSC flakes, a high sulfur loading (HSL) electrode can be realized due to their high layer bulk density. Compared to our previous work in multifunctional Co–N–C composites, the cellular Co@N–C composite displays a distinct enhancement in the sulfur content, sulfur loading, cycle stability, and rate performance. Benefiting from the cellular morphology, a composite with an HSC of 93.6 wt % and an electrode with an HSL of 7.5 mg cm–2 can be obtained simultaneously, which exhibited excellent rate performance up to 10 C (3.6 mg cm–2) and great cycling stability.Keywords: Co@N−C; high sulfur content (HSC); high sulfur loading (HSL); honeycomb; Li−S battery;

High utilization and loading of sulfur in cathodes holds the key in the realization of Li–S batteries. We here synthesized a Co4N mesoporous sphere, which was made up of nanosheets, via an easy and convenient method. This material presents high affinity, speedy trapping, and absorbing capacity for polysulfides and acts as a bifunctional catalysis for sulfur redox processes; therefore it is an ideal matrix for S active material. With such a mesoporous sphere used as a sulfur host in Li–S batteries, extraordinary electrochemistry performance has been achieved. With a sulfur content of 72.3 wt % in the composite, the Co4N@S delivered a high specific discharge capacity of 1659 mAh g–1 at 0.1 C, almost reaching its theoretic capacity. Also, the battery exhibited a large reversible capacity of about 1100 mAh g–1 at 0.5 C and 1000 mAh g–1 at 1 C after 100 cycles. At a high rate of 2 C and 5 C, after 300 cycles, the discharge capacity finally stabilized at 805 and 585 mAh g–1. Even at a 94.88% sulfur content, the cathode can still deliver an extremely high specific discharge capacity of 1259 mAh g–1 with good cycle performance.Keywords: adsorb; catalyze; cobalt nitride; high sulfur loading; Li−S battery; mesoporous sphere;

Metal–organic frameworks (MOFs) may be promising multifunctional materials attributing to their large internal surface areas and high porosities that can favor charge transport. In this article, MIL-53(Fe) has been investigated as an anode material for Li-ion batteries. It showed decent performance on account of the redox reaction (Fe3+ ↔ Fe0). However, the carboxylate groups of terephthalate acid ligands did not show electrochemical activity due to the poor electrical conductivity of MIL-53(Fe) and the formation of thick solid electrolyte interphase layer. In this case, reduced graphene oxide (RGO) was then composited to resolve the problem, which named as MIL-53(Fe)@RGO. The composite exhibited better electrochemical performance than the sole MIL-53(Fe). Specifically, a reversible discharge specific capacity of 550 mA h g−1 could be still achieved at 100 mA g−1 after 100 cycles within the voltage range of 0.01–3.0 V, an reversible discharge capacity of about 300 mA h g−1 was obtained even at 2 A g−1. These values are much higher than those of currently used graphitic materials. RGO makes it even more possibility for MOFs to be adopted as electrode materials for Li-ion batteries.

High-performance and stable electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) that can work at the same pH condition are in high demand for overall water-splitting systems. Here, we report a partially oxidized Co in situ anchored in a porous nitrogen-doped nano carbon dodecahedron and its application in electrocatalytic overall water splitting. The Co3O4 shell worked as an efficient charge separation layer while the metallic Co inner core transported the separated charges immediately to the N-carbon framework. By constructing a Schottky barrier between the Co3O4 shell and metallic Co core, the charge separation and transport processes were speeded up and thus the electrocatalytic activities were dramatically enhanced.

Lithium–sulfur (Li–S) batteries have been identified as the most promising options for energy storage because of their high theoretical capacity and environmental friendliness. However, low utilization of sulfur in the cathode and the shuttle effect, which leads to a poor cycle life, hinder the realization of Li–S batteries. Herein, we have designed a new type of rGO-supported TiN-nanoparticle (TiN/rGO) multifunction cover layer via an in situ synthesis method. The excellent blocking effect of lithium polysulfides and outstanding catalytic ability and superior electron conductivity of the TiN/rGO cover layer favor the development of a macro-chamber for S conversion reactions (MCSR) at a macroscopic scale. This macro-chamber, in which either pure sulfur powders or sulfur-based composites can be directly adopted as active materials, can significantly reduce the shuttle effect and increase sulfur utilization for lithium–sulfur batteries. When the S powder loading is as high as 8 mg cm−2, the battery continues to deliver outstanding electrochemical performance and cycling stability. Via this MCSR design, indispensable support materials for S and additives for electrolyte will no longer be needed in the current Li–S cells.

The rechargeable lithium–sulfur battery is regarded as a promising option for electrochemical energy storage systems owing to its high energy density, low cost and environmental friendliness. Further development of the Li–S battery, however, is still impeded by capacity decay and kinetic sluggishness caused by the polysulfide shuttle and electrode/electrolyte interface issues. Herein, a new type of metal–organic-framework-derived sulfur host containing cobalt and N-doped graphitic carbon (Co–N-GC) was synthesized and reported, in which the catalyzing for S redox, entrapping of polysulfides and an ideal electronic matrix were successfully achieved synchronously, leading to a significant improvement in the Li–S performance. The large surface area and uniform dispersion of cobalt nanoparticles within the N-doped graphitic carbon matrix contributed to a distinct enhancement in the specific capacity, rate performance and cycle stability for Li–S batteries. As a result of this multi-functional arrangement, cathodes with a high sulfur loading of 70 wt% could operate at 1C for over 500 cycles with nearly 100% coulombic efficiency and exhibited an outstanding high-rate response of up to 5C, suggesting that the S@Co–N-GC electrode was markedly improved by the proposed strategy, demonstrating its great potential for use in low-cost and high-energy Li–S batteries.

Lithium/sulfur (Li/S) batteries have become promising future power sources owing to the high energy density. Carbon materials are the most used sulfur hosts, but their ability to adsorb polysulfide intermediates has been unreliable, thus recently many researchers have turned their interest to metal oxide materials. Here, we manufactured a composite of carbon nanotubes modified with manganese oxide nanoparticles (CNTs/MnO) as a sulfur host material. In Li/S cells, the CNTs/MnO–S cathode showed a rather better cycling stability over 100 cycles than a CNTs–S cathode with the same carbon/sulfur weight ratio of about 1:8. In addition, the CNTs/MnO–S cathode presented an initial discharge capacity of 716 mA h g−1 at a high current density of 5.0C, in contrast to the result of only 415 mA h g−1 with the CNTs–S cathode. Physical and electrochemical characterization proved that the MnO modification does not vary the surface area of the CNTs but lowers their electrical conductivity. By carefully comparing the differences in the 1st discharge capacities of the two cathodes, the MnO modification could obviously improve the initial utilization of S especially at high current densities. The improved electrochemical characteristics of the CNTs/MnO–S electrode can be attributed to its properties of a stronger adsorption capability for polysulfides.

Nonaqueous lithium–oxygen (Li–O2) batteries are considered as the most promising energy storage systems, because of their very high energy densities, which are significantly greater than those of lithium-ion batteries. Recently, carbon materials have been widely used as cathode catalysts for Li–O2 batteries due to their outstanding conductivity. However, side reactions are inevitable when the carbon materials are exposed to the Li2O2 product and the organic electrolytes, leading to degradation in their cycling performances. Herein, we propose a simplified strategy, which combines the template method and in situ growth approach in order to establish a three-dimensional (3D) mesoporous graphene-like carbon structure, and growth of a uniform layer of ruthenium particles on it. The as-prepared 3D ruthenium@mesoporous graphene-like carbon material delivers a reversible capacity of about 6433 mA h g−1 (based on the total mass of the composite) at a current density of 200 mA g−1, when it is used as a cathode catalyst for Li–O2 batteries. Under a curtaining capacity of 500 mA h g−1, it exhibits an extremely low charge voltage of 3.20 V (only 240 mV higher than the thermodynamic potential) and a high discharge voltage of 2.84 V at a current density of 100 mA g−1.

Sodium ion batteries (SIBs), based on earth-abundant and cost-effective elements, have attracted increasing attention. Carbon-based materials are still the most potential anode materials for SIBs. Because of insufficient interlayer spacing, graphite-based materials used currently in lithium ion batteries are not suitable for SIB anodes. Herein, combining macro-construction and micro-modification, we design and prepare novel SN-co-doped hollow carbon spheres (SN-HCSs) by a new method. The S and N play different roles during sodium ion storage. Due to the hierarchical porous structure and heteroatoms including S and N, the SN-HCS anode exhibits superior performance, especially with high rate capability (110 mA h g−1 at a current density of 10 A g−1) and excellent cyclic stability (cycle as long as 2000 cycles with only 0.0195 mA h g−1 specific capacity decay for each cycle).

A nano-sized LiMnPO4@C core@shell structure was prepared through a facile two-step method. Oleylamine was introduced in the synthesis process using as both solvent and carbon source. The LiMnPO4@C structure has a particle size smaller than 40 nm with uniform 2–3 nm carbon coating layers, which interweave to form a secondary micrometer-sized mesoporous structure. The as-prepared LiMnPO4@C showed a high capacity of 168 mAh g−1 at 0.1 C and 105 mAh g−1 at 5 C applied as a cathode electrode for lithium ion batteries. The thin layer carbon coating not only increases LiMnPO4 in electronic and ionic conductivity, but also enhances its cycling ability by stabilizing the solid electrolyte interface.A hierarchical nano-sized and uniform carbon coated LiMnPO4@C was fabricated via an oleylamine-mediated method, which showed excellent electrochemical performance.

•A polypyrrole/reduced graphene oxide (PPy/rGO) composite was prepared from in-situ hybridization of graphene oxide and pyrrole without additional oxidant.•Nitrogen doped graphene (NG) was obtained from the calcination of the PPy/rGO composite under 1500 °C and was confirmed with abundant pyridinic type nitrogen doping.•NG was employed as a conductive Lewis base matrix of sulfur cathode and the obtained composite cathode exhibited ultra-high rates and reversible capacity.•The excellent electrochemical performance can be attributed to the efficient adsorption of Li2Sn (n=4-8) on the pyridinic-N enriched NG surface.To improve the electrochemical performance of lithium sulfur batteries, a conductive Lewis base matrix, nitrogen doped graphene (NG), was prepared here through a facile strategy of annealing a polypyrrole/reduced graphene oxide composite. The obtained NG was demonstrated with enriched pyridinic-N doping and was employed as the matrix of sulfur cathode with ultra-high rates, reversible capacity and high coulombic efficiency. The improved performance can be attributed to the high conductivity of the NG and the enhanced adsorption energy of Li2Sn (n=4-8) on the NG surface. The NG can act not only as an electronic conductive network but also as a Lewis base “catalyst” matrix that promotes the higher Li2Sn to be further oxidized completely to S8 as demonstrated in the cyclic voltammetry curve, which can thus significantly improve the sulfur utilization and cyclic stability even at a high sulfur loading of 75% (w/w) in the S@NG composite.

Sulfur and polysulfides play important roles on the environment and energy storage systems, especially in the recent hot area of high energy density of lithium–sulfur (Li–S) batteries. However, the further development of Li–S battery is still retarded by the lack of complete mechanistic understanding of the sulfur redox process. Herein we introduce a conductive Lewis base matrix which has the ability to enhance the battery performance of Li–S battery, via the understanding of the complicated sulfur redox chemistry on the electrolyte/carbon interface by a combined in operando Raman spectroscopy and density functional theory (DFT) method. The higher polysulfides, Li2S8, is found to be missing during the whole redox route, whereas the charging process of Li–S battery is ended up with the Li2S6. DFT calculations reveal that Li2S8 accepts electrons more readily than S8 and Li2S6 so that it is thermodynamically and kinetically unstable. Meanwhile, the poor adsorption behavior of Li2Sn on carbon surface further prevents the oxidization of Li2Sn back to S8 upon charging. Periodic DFT calculations show that the N-doped carbon surface can serve as conductive Lewis base “catalyst” matrix to enhance the adsorption energy of Li2Sn (n = 4–8). This approach allows the higher Li2Sn to be further oxidized into S8, which is also confirmed by in operando Raman spectroscopy. By recovering the missing link of Li2S8 in the whole redox route, a significant improvement of the S utilization and cycle stability even at a high sulfur loading (70%, m/m) in the composite on a simple super P carbon.

Surface modification and fabrication of composite structures have been reported to be efficient strategies to obtain cathode materials with satisfactory electrochemical performance. Herein, a combined method to fabricate an oxidized spinel outer layer containing Ni3+ is demonstrated to be an effective method to improve the rate capability as well as cyclability of Li-rich cathode materials. Such a surface modification process is carried out through a facile treatment with ammonium persulfate, and a homogeneous layered-spinel structure is thus obtained, which contains intimately connected layered bulk and an oxidized spinel outer layer. The thus-obtained material delivers a charge/discharge capacity of 330.5/308.7 mA h g−1, with an enhanced coulombic efficiency up to 93.4% and a rather fascinating rate capability of 169.1 mA h g−1, 100.8 mA h g−1, and 68.2 mA h g−1 at 10 C, 20 C and 30 C, respectively, and a much superior cycle performance, which is a stable capacity with no fading after prolonged 200 cycles.

•Hollow-in-hollow structured HIHCS was synthesized via a facile templating strategy.•The HCS core and hollow carbon shell constitute the hollow-in-hollow structure.•The HIHCS exhibited superior rate capability and cycle stability as anode material.•The excellent performance is attributed to the unique hollow-in-hollow structure.Hollow spheres structured materials have been intensively pursued due to their unique properties for energy storage. In this paper, hollow-in-hollow carbon spheres (HIHCS) with a multi-shelled structure were successfully synthesized using a facile hard-templating procedure. When evaluated as anode material for lithium-ion batteries, the resultant HIHCS anode exhibited superior capacity and cycling stability than HCS. It could deliver reversible capacities of 937, 481, 401, 304 and 236 mAh g−1 at current densities of 0.1 A g−1, 1 A g−1, 2 A g−1, 5 A g−1 and 10 A g−1, respectively. And capacity fading is not apparent in 500 cycles at 5 A g−1. The excellent performance of the HIHCS anode is ascribed to its unique hollow-in-hollow structure and high specific surface area.

A sulfide-based SEI layer was formed on the surface of a LiNi0.5Mn1.5O4 cathode by using a sulfolane–carbonate mixed solvent electrolyte, which led to an improvement in the electrochemical performance. Moreover, the thermal stability of the LiNi0.5Mn1.5O4 cathode was also significantly improved in the presence of the SEI layer. ARC (Accelerating Rate Calorimetry) tests showed that the self-heating rate of the delithiated LiNi0.5Mn1.5O4 material in the sulfolane–carbonate electrolyte was suppressed.

Carbon is essential for the oxygen electrode in non-aqueous lithium–oxygen (Li–O2) batteries for improving the electron conductivity of the electrode. However, it also leads to some side reactions when exposed to the Li2O2 product and the electrolyte, limiting the round-trip efficiency and coulombic efficiency of the batteries. In this paper, a carbon-embedded α-MnO2@graphene nanosheet (α-MnO2@GN) composite is introduced as a highly effective catalyst for Li–O2 batteries. X-ray photoelectron spectroscopy (XPS) analysis showed that the Li2CO3 by-product was significantly reduced due to the isolation of carbon with the electrolyte and Li2O2. Thus, the composite could deliver a reversible capacity of ∼2413 mAh g−1 based on the total mass of the composite with an extremely high discharge voltage of ∼2.92 V (only 40 mV lower than the thermodynamic potential) and a low charge voltage of ∼3.72 V at a current density of 50 mA g−1. The round-trip efficiency is calculated to be ∼78% with a coulombic efficiency of almost 100%.

In this study, the in situ growth of tin dioxide (SnO2) nanoparticles on reduced graphene oxide (rGO) has been realized using a hydrothermal method. The size of the SnO2 nanoparticles in the SnO2/rGO composites prepared by three different procedures is about 5 nm, and they are well dispersed on rGO. When applied as anode materials for lithium-ion batteries, we found that the composites synthesized from the stannous oxalate precursor showed the best rate performance and highest cyclic stability. The surface status of the composites, including interactions between SnO2 and rGO and surface chemical components, was investigated in detail in order to understand why the composites prepared using different procedures displayed vastly different electrochemical performances. The results presented here describe a new approach for the synthesis of uniform and nanosized metal-oxide/rGO composites with excellent electrochemical performance.

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In this paper, a hierarchical nanostructure LiFePO4@C composite was firstly fabricated by an oleylamine mediated method. The oleylamine played a multifunctional role in restricting the particle size and forming the porous nano-structure of LiFePO4@C composite. Benefiting from its hierarchical structure, LiFePO4@C exhibited superior electrochemical performance, especially at low temperature. It can deliver a capacity of 117 mA h g−1 at a current density of up to 700 mA g−1 (about 5 C) at −20 °C.

•MnO/rGO was firstly prepared by a pyrolysis method using rGO as the starting material.•Only 6% graphene in mass was introduced in the composite.•MnO particles with average size of ∼30 nm were uniformly dispersed on the rGO surface.•The composite exhibited excellent rate and cycling performance as anode material.Reduced graphene oxide was firstly introduced to synthesize MnO/rGO nanocomposite by a facile pyrolysis method. MnO nanoparticles with an average size of about 30 nm were uniformly decorated on the rGO matrix. Note that the mass content of rGO in the composite is only ∼6%. The MnO/rGO composite exhibited superior rate capability and improved cycling stability due to the high conductivity and two dimension (2D) structure of the reduced graphene oxide. It could deliver reversible capacities of 952.2, 727.9, 608.7 and 422.4 mAh g−1 at current densities of 0.1 A g−1, 1 A g−1, 2 A g−1 and 5 A g−1, respectively and without obvious capacity fading during 150 cycles at the current density of 0.5 A g−1.

A MnO2 nanoflake–reduced graphene oxide (MnO2–rGO) composite was synthesized by a facile solution method. The composite exhibited excellent electrochemical performance with a reversible capacity of 1430 mA h g−1 and 520 mA h g−1 at current densities of 0.1 A g−1 and 10 A g−1, respectively. MnO2 in the composite was proved to be fully activated and went through a complete conversion reaction. The improved kinetics in the MnO2–rGO composite electrode were evidenced by Electrochemical Impedance Spectroscopy (EIS) results, accounting for its extraordinary electrochemical properties compared with that in a simple MnO2–rGO mixture electrode. Due to the uniform dispersion and firm anchoring of MnO2 nanoflakes on the rGO surface, the volume expansion of MnO2 during the charge–discharge process was significantly alleviated. It showed excellent cyclic performance with an extremely large capacity of 1000 mA h g−1 maintained after 200 cycles at the current density of 1 A g−1.

This paper reports a weak interaction between metal oxide and graphene in the Fe3O4/graphene composite, which results in the superior electrochemical performance.

Through in situ nucleation and growth of α-MnO2 nanorods on graphene nanosheets (GNs), a α-MnO2 nanorod/GN hybrid was synthesized and employed as the catalyst for non-aqueous lithium oxygen (Li–O2) batteries. The α-MnO2/GN hybrid showed excellent catalytic property. It was demonstrated that the catalytic performance of α-MnO2 for ORR and OER was not only associated with the morphology and size of the particles but also with their combination with graphene. The developed in situ synthetic strategy can also be applied to prepare analogous MOx/GN hybrids used in Li–O2 batteries and other energy storage systems.

This communication reports a novel intermolecular interaction for structural DNA nanotechnology.

A new strategy was applied to synthesise a porous nanostructure of α-Fe2O3 xerogel assembled from nanocrystalline particles (∼5 nm) with abundant mesopores (∼3 nm) using a hydrothermal method. The α-Fe2O3 xerogel exhibits excellent cycling performance (up to 1000 cycles) and rate capability (reversible discharging capacity 280 mAh g−1 at 10 C) as a potential anode for high power lithium-ion batteries.

A hierarchical S/MWCNT nanomicrosphere for lithium/sulfur batteries with a high power and energy density as well as an excellent cycle life is introduced. Sulfur was uniformly coated on the surface of functional MWCNTs, which serves as a carbon matrix, to form a typical nanoscale core–shell structure with a sulfur layer of thickness 10–20 nm. Then the nanoscale sulfur intermediate composite was ball-milled to form interwoven and porous sphere architecture with large pores (around 1 μm to 5 μm). Different from most sulfur/carbon materials with micropore and mesopore structure, the micrometre scale S/MWCNT nanomicrosphere with a large pore structure could also exhibit high sulfur utilization and cycle retention. It could maintain a reversible capacity of 1000 mA h g−1 after 100 cycles at 0.3 A g−1 current density. And it even remained 780 mA h g−1 after 200 cycles at 0.5 A g−1 and 650 mA h g−1 after 200 cycles at 1 A g−1, showing a significant cyclability enhancement. It is believed that under the collective effect of hierarchical architecture, as well as the existence of carboxyl functional groups, sulfur/carbon materials with large pores could also exhibit an excellent electrochemical performance. The synthesis process introduced here is simple and broadly applicable, which would not only be beneficial to design new materials for lithium sulfur batteries but can also be extended to many different electrode materials for lithium ion batteries.

In this work, a novel nano-sulfur/MWCNTs composite with modified multi-wall carbon nano-tubes (MWCNTs) as sulfur-fixed matrix for Li/S battery is reported. Based on different solubility of sulfur in different solvents, nano-sulfur/MWCNTs composite was prepared by solvents exchange method. The composite was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The modified MWCNTs are considered that not only acts as a conducting material, but also a matrix for sulfur. The electrochemical performance of the nano-sulfur/MWCNTs composite was tested. The results indicated that nano-sulfur/MWCNTs composite had the specific capacity of 1380 mAh g−1, 1326 mAh g−1 and 1210 mAh g−1 in the initial cycle at 100 mA g−1, 200 mA g−1 and 300 mAh g−1 discharge rates respectively, and remained a reversible capacity of 1020 mAh g−1, 870 mAh g−1 and 810 mAh g−1 after 30 cycles. The electrochemical performances confirm that the modified MWCNTs as sulfur-fixed matrix show better ability than any other carbon in cathode of Li/S batteries that had been reported.

The core–shell carbon/sulfur material with high performance is prepared by a facile and fast deposit method in an aqueous solution. As sulfur ratio is 85% (w/w) in the composite, scanning electron microscope (SEM) and transmission electron microscope (TEM) observation show that the moniliform particles with 10 nm sulfur shells preserve the morphology of carbon cores. Tested as the cathode material in a lithium cell with binary organic electrolyte at room temperature, the composite shows excellent electrochemical performance. It exhibits a specific capacity up to 1232.5 mAh g−1 at the initial discharge and its specific capacity remained above 800 mAh g−1 after 50 cycles. Meanwhile, the composite also exhibits the high-rate behavior at 800 mA g−1 of current density. Assuming a complete reaction to the final product, Li2S, the utilization of the electrochemically active sulfur is about 85% at the initial cycle. Electrochemical impedance spectroscopy (EIS) is introduced to understand the impact of the microstructure of composite on electrochemistry. According to our study, a novel core–shell structural carbon/sulfur material is proposed and the key factors of the preparation are discussed.

SnOx thin films were prepared by reactive radio frequency magnetron sputtering with different sputtering powers. X-ray photoelectron spectroscopy suggested that all the films have similar chemical stoichiometry as SnO1.5. X-ray diffraction and transmission electro microscopy results showed that crystal size of the SnOx thin films gradually increases with increase of sputtering power from 50 to 150 W. Cyclic voltammetry and galvanostatic charge/discharge cycling measurements indicated that the electrochemical properties of SnOx films strongly rely on their crystal sizes as well as surface morphologies. The SnOx film deposited at sputtering power of 120 W exhibits the best electrochemical performances. It could deliver a reversible capacity of 670 μAh cm−2 μm−1 at 50 μA cm−2 in the voltage range of 0.1–1.2 V up to 50 cycles.

As a carbon alternative anode for Li-ion battery, we synthesized amorphous Ni–Sn alloy and crystalline Ni3Sn2 employing different methods that lead to different morphology based on the concept of “buffer matrix”. The characteristics of the nickel–tin alloys were examined by XRD, SEM and DTA analysis. The electrochemical performance of the materials was investigated using a cell incorporated with a lithium metal counter electrode separated from the working electrode by a microporous polyethylene separator material (Celgard 2300) in the electrolyte of 1 M LiPF6 in EC+DMC+DEC. Among the different Sn–Ni alloys synthesized by different approaches, Ni3Sn2 is a promising anode material for high rate discharge and large size Li-ion battery because of its good electronic conductivity and excellent safety.

High-performance and stable electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) that can work at the same pH condition are in high demand for overall water-splitting systems. Here, we report a partially oxidized Co in situ anchored in a porous nitrogen-doped nano carbon dodecahedron and its application in electrocatalytic overall water splitting. The Co3O4 shell worked as an efficient charge separation layer while the metallic Co inner core transported the separated charges immediately to the N-carbon framework. By constructing a Schottky barrier between the Co3O4 shell and metallic Co core, the charge separation and transport processes were speeded up and thus the electrocatalytic activities were dramatically enhanced.

Lithium/sulfur (Li/S) batteries have become promising future power sources owing to the high energy density. Carbon materials are the most used sulfur hosts, but their ability to adsorb polysulfide intermediates has been unreliable, thus recently many researchers have turned their interest to metal oxide materials. Here, we manufactured a composite of carbon nanotubes modified with manganese oxide nanoparticles (CNTs/MnO) as a sulfur host material. In Li/S cells, the CNTs/MnO–S cathode showed a rather better cycling stability over 100 cycles than a CNTs–S cathode with the same carbon/sulfur weight ratio of about 1:8. In addition, the CNTs/MnO–S cathode presented an initial discharge capacity of 716 mA h g−1 at a high current density of 5.0C, in contrast to the result of only 415 mA h g−1 with the CNTs–S cathode. Physical and electrochemical characterization proved that the MnO modification does not vary the surface area of the CNTs but lowers their electrical conductivity. By carefully comparing the differences in the 1st discharge capacities of the two cathodes, the MnO modification could obviously improve the initial utilization of S especially at high current densities. The improved electrochemical characteristics of the CNTs/MnO–S electrode can be attributed to its properties of a stronger adsorption capability for polysulfides.

Sodium ion batteries (SIBs), based on earth-abundant and cost-effective elements, have attracted increasing attention. Carbon-based materials are still the most potential anode materials for SIBs. Because of insufficient interlayer spacing, graphite-based materials used currently in lithium ion batteries are not suitable for SIB anodes. Herein, combining macro-construction and micro-modification, we design and prepare novel SN-co-doped hollow carbon spheres (SN-HCSs) by a new method. The S and N play different roles during sodium ion storage. Due to the hierarchical porous structure and heteroatoms including S and N, the SN-HCS anode exhibits superior performance, especially with high rate capability (110 mA h g−1 at a current density of 10 A g−1) and excellent cyclic stability (cycle as long as 2000 cycles with only 0.0195 mA h g−1 specific capacity decay for each cycle).

Nonaqueous lithium–oxygen (Li–O2) batteries are considered as the most promising energy storage systems, because of their very high energy densities, which are significantly greater than those of lithium-ion batteries. Recently, carbon materials have been widely used as cathode catalysts for Li–O2 batteries due to their outstanding conductivity. However, side reactions are inevitable when the carbon materials are exposed to the Li2O2 product and the organic electrolytes, leading to degradation in their cycling performances. Herein, we propose a simplified strategy, which combines the template method and in situ growth approach in order to establish a three-dimensional (3D) mesoporous graphene-like carbon structure, and growth of a uniform layer of ruthenium particles on it. The as-prepared 3D ruthenium@mesoporous graphene-like carbon material delivers a reversible capacity of about 6433 mA h g−1 (based on the total mass of the composite) at a current density of 200 mA g−1, when it is used as a cathode catalyst for Li–O2 batteries. Under a curtaining capacity of 500 mA h g−1, it exhibits an extremely low charge voltage of 3.20 V (only 240 mV higher than the thermodynamic potential) and a high discharge voltage of 2.84 V at a current density of 100 mA g−1.

Carbon is essential for the oxygen electrode in non-aqueous lithium–oxygen (Li–O2) batteries for improving the electron conductivity of the electrode. However, it also leads to some side reactions when exposed to the Li2O2 product and the electrolyte, limiting the round-trip efficiency and coulombic efficiency of the batteries. In this paper, a carbon-embedded α-MnO2@graphene nanosheet (α-MnO2@GN) composite is introduced as a highly effective catalyst for Li–O2 batteries. X-ray photoelectron spectroscopy (XPS) analysis showed that the Li2CO3 by-product was significantly reduced due to the isolation of carbon with the electrolyte and Li2O2. Thus, the composite could deliver a reversible capacity of ∼2413 mAh g−1 based on the total mass of the composite with an extremely high discharge voltage of ∼2.92 V (only 40 mV lower than the thermodynamic potential) and a low charge voltage of ∼3.72 V at a current density of 50 mA g−1. The round-trip efficiency is calculated to be ∼78% with a coulombic efficiency of almost 100%.

A sulfide-based SEI layer was formed on the surface of a LiNi0.5Mn1.5O4 cathode by using a sulfolane–carbonate mixed solvent electrolyte, which led to an improvement in the electrochemical performance. Moreover, the thermal stability of the LiNi0.5Mn1.5O4 cathode was also significantly improved in the presence of the SEI layer. ARC (Accelerating Rate Calorimetry) tests showed that the self-heating rate of the delithiated LiNi0.5Mn1.5O4 material in the sulfolane–carbonate electrolyte was suppressed.

In this study, the in situ growth of tin dioxide (SnO2) nanoparticles on reduced graphene oxide (rGO) has been realized using a hydrothermal method. The size of the SnO2 nanoparticles in the SnO2/rGO composites prepared by three different procedures is about 5 nm, and they are well dispersed on rGO. When applied as anode materials for lithium-ion batteries, we found that the composites synthesized from the stannous oxalate precursor showed the best rate performance and highest cyclic stability. The surface status of the composites, including interactions between SnO2 and rGO and surface chemical components, was investigated in detail in order to understand why the composites prepared using different procedures displayed vastly different electrochemical performances. The results presented here describe a new approach for the synthesis of uniform and nanosized metal-oxide/rGO composites with excellent electrochemical performance.

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In this paper, a hierarchical nanostructure LiFePO4@C composite was firstly fabricated by an oleylamine mediated method. The oleylamine played a multifunctional role in restricting the particle size and forming the porous nano-structure of LiFePO4@C composite. Benefiting from its hierarchical structure, LiFePO4@C exhibited superior electrochemical performance, especially at low temperature. It can deliver a capacity of 117 mA h g−1 at a current density of up to 700 mA g−1 (about 5 C) at −20 °C.

Surface modification and fabrication of composite structures have been reported to be efficient strategies to obtain cathode materials with satisfactory electrochemical performance. Herein, a combined method to fabricate an oxidized spinel outer layer containing Ni3+ is demonstrated to be an effective method to improve the rate capability as well as cyclability of Li-rich cathode materials. Such a surface modification process is carried out through a facile treatment with ammonium persulfate, and a homogeneous layered-spinel structure is thus obtained, which contains intimately connected layered bulk and an oxidized spinel outer layer. The thus-obtained material delivers a charge/discharge capacity of 330.5/308.7 mA h g−1, with an enhanced coulombic efficiency up to 93.4% and a rather fascinating rate capability of 169.1 mA h g−1, 100.8 mA h g−1, and 68.2 mA h g−1 at 10 C, 20 C and 30 C, respectively, and a much superior cycle performance, which is a stable capacity with no fading after prolonged 200 cycles.

A new strategy was applied to synthesise a porous nanostructure of α-Fe2O3 xerogel assembled from nanocrystalline particles (∼5 nm) with abundant mesopores (∼3 nm) using a hydrothermal method. The α-Fe2O3 xerogel exhibits excellent cycling performance (up to 1000 cycles) and rate capability (reversible discharging capacity 280 mAh g−1 at 10 C) as a potential anode for high power lithium-ion batteries.

This communication reports a novel intermolecular interaction for structural DNA nanotechnology.

A hierarchical S/MWCNT nanomicrosphere for lithium/sulfur batteries with a high power and energy density as well as an excellent cycle life is introduced. Sulfur was uniformly coated on the surface of functional MWCNTs, which serves as a carbon matrix, to form a typical nanoscale core–shell structure with a sulfur layer of thickness 10–20 nm. Then the nanoscale sulfur intermediate composite was ball-milled to form interwoven and porous sphere architecture with large pores (around 1 μm to 5 μm). Different from most sulfur/carbon materials with micropore and mesopore structure, the micrometre scale S/MWCNT nanomicrosphere with a large pore structure could also exhibit high sulfur utilization and cycle retention. It could maintain a reversible capacity of 1000 mA h g−1 after 100 cycles at 0.3 A g−1 current density. And it even remained 780 mA h g−1 after 200 cycles at 0.5 A g−1 and 650 mA h g−1 after 200 cycles at 1 A g−1, showing a significant cyclability enhancement. It is believed that under the collective effect of hierarchical architecture, as well as the existence of carboxyl functional groups, sulfur/carbon materials with large pores could also exhibit an excellent electrochemical performance. The synthesis process introduced here is simple and broadly applicable, which would not only be beneficial to design new materials for lithium sulfur batteries but can also be extended to many different electrode materials for lithium ion batteries.