•Uniform Zn2SnO4/graphene composites with high purity of Zn2SnO4 are prepared by a facile hydrothermal process.•The weight percentage of graphene in the composites has a big effect on the electrochemical performance.•As anode materials for lithium ion batteries, the Zn2SnO4/graphene exhibit superior electrochemical properties.Graphene-based composites are of great interest to the scientific field due to their good physical and chemical properties. In this work, Zn2SnO4/graphene (Zn2SnO4/G) composites with high purity are hydrothermally prepared. The Zn2SnO4 nanoparticles are homogeneously anchored on the graphene nanosheets with a diameter less than 20 nm. The aggregations of Zn2SnO4 can be greatly reduced due to the introducing of graphene nanosheets. As anode materials for lithium ion batteries (LIBs), Zn2SnO4/G exhibits good electrochemical properties. The effects of graphene content in the composite on the electrochemical properties are also studied. The Zn2SnO4/G composite can deliver the initial discharge/charge capacities of 1367/829 mA h g−1 at the current density of 1 A g−1 and retain 848/842 mA h g−1 after 200 cycles, respectively. The good electrochemical properties are attributed to the synergistic effect of the nanocomposites.

Transition metal chalcogenides have attracted increasing attentions as electrode materials for energy storage devices. Their electrochemical properties are largely determined by morphologies and structures. In this paper, we reported the fabrication of CoSe2/C dodecahedra with tunable interior structures, such as solid, yolk-shell, and double-shell structured interiors. Dodecahedron-shaped cobalt-organic frameworks are used as the sacrificial template, in which the cobalt species react with selenium to in situ form CoSe2 nanoparticles. Moreover, the organic framework is converted into nitrogen-doped carbon framework. The controllable preparation of CoSe2/C composite with diversified interior structures can be realized by a temperature determined annealing process in argon atmosphere. In particular, the unusual double-shell structured composites with non-spherical shells and heterogeneous intervals are formed. The possible formation mechanism of the structure is proposed. As electrode materials for supercapacitors, the double-shelled CoSe2/C composites exhibit high capacitance, good rate capability and long-term cycling stability.

Two-dimensional (2D) porous hybrid bimetallic transition metal oxide (TMO) nanosheets demonstrated promising applications in the energy field due to their large surface areas, porous structure, and synergistic effects. However, the synthesis of these materials is still a big challenge. In this study, we rationally designed a facile strategy to prepare 2D porous hybrid bimetallic TMO (Co3O4/ZnO) nanosheets with novel structural and electrochemical synergistic effects. Derived from bimetallic MOF nanosheets, the porous hybrid nanosheets possess high surface areas and large pore volume. In particular, they are rich in oxygen vacancies, which provide more active sites for electrochemical reaction. Moreover, the harmonious multi-step conversion reaction between Co3O4 and ZnO was helpful for volume buffering, leading to an outstanding cyclic stability. With remarkable structural features and harmonious electrochemical behaviors, the Co3O4/ZnO hybrids exhibit excellent electrochemical performances as anodes for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). This study also introduces a new strategy to prepare 2D porous hybrid bimetallic TMO nanosheets, which can find wide applications in energy storage, catalysis, sensors, and information storage devices.

Doping of N atoms into the carbonacous materials can generate extrinsic defects and more active sites, improve electrode wettability and also broaden the interlayer distance of carbon, hence promote Na storage capacity and high rate capability. Herein, we report the nitrogen-doped carbon nanosheets materials (PPyCs) obtained from pyrolysis of Polypyrrole coated graphene oxides. The pyrolysis temperature plays an important role on the electrochemical performance of PPyCs. With thermal treatment at 400, 600 and 800 °C, PPyCs have different content of N doping, and the doped N shows different existential forms. The PPyCs thermal treated at 600 °C (PPyC-600) exhibit a reversible capacity of 388.8 mA h g−1 at a current density of 100 mA g−1, and even at a high current density of 10 A g−1, high capacity of 198.6 mA h g−1 is maintained after 10,000 cycles, demonstrating outstanding cyclic stability, and high-rate capability. Furthermore, the assembled NVP/PPyC-600 full-cell demonstrates a high capacity of 122.2 mA h g−1 at a current density of 100 mA g−1 after 100 cycles, indicating the practical application of PPyCs nanosheets anode in sodium ion batteries.Nitrogen-doped carbon nanosheets materials are prepared from pyrolysis of Polypyrrole coated graphene oxides. We analyze the existential form of doped N in carbon nanosheets under different annealing temperature and the influence of the content of different N species on the electrochemical performance of carbon anodes for SIBs. Importantly, the N-doped carbon nanosheets demonstrate outstanding cyclic stability and high-rate capability for SIBs.Download high-res image (409KB)Download full-size image

•TiO2 nanorods grown on carbon fiber cloth are prepared.•TiO2 nanorods/CFC is investigated as binder-free anode for Na-ion batteries.•For NIBs, TiO2/CFC show excellent rate capability and long cycle performance.•A flexible Na-ion capacitor, TiO2/CFC//carbon fibers, is assembled.•TiO2/CFC//CFs show high energy and power density with a long cycle life.Na-ion batteries (NIBs) and Na-ion capacitors (NICs) have tremendous potential in many large-scale energy storage applications. Here, NIBs based on TiO2 nanorods/carbon fiber cloth (TiO2/CFC) flexible anode materials are introduced. The as-prepared flexible anode exhibited a notable rate performance and high specific capacity of 148.7 mAh g−1 after 2000 cycles at 1 A g−1. Furthermore, we demonstrate a highly flexible NIC system employing the TiO2/CFC anode and carbon fibers (CFs) as the cathode material. The flexible TiO2/CFC//CFs NIC device achieved a high energy density of 73.8 Wh kg−1 and high power density of 13,750 W kg−1, as well as long-term cycling stability over 4000 cycles with a capacity retention of ∼90%.Download high-res image (215KB)Download full-size image

AbstractSodium (Na) super ion conductor structured Na3V2(PO4)3 (NVP) is extensively explored as cathode material for sodium-ion batteries (SIBs) due to its large interstitial channels for Na+ migration. The synthesis of 3D graphene-like structure coated on NVP nanoflakes arrays via a one-pot, solid-state reaction in molten hydrocarbon is reported. The NVP nanoflakes are uniformly coated by the in situ generated 3D graphene-like layers with the thickness of 3 nm. As a cathode material, graphene covered NVP nanoflakes exhibit excellent electrochemical performances, including close to theoretical reversible capacity (115.2 mA h g−1 at 1 C), superior rate capability (75.9 mA h g−1 at 200 C), and excellent cyclic stability (62.5% of capacity retention over 30000 cycles at 50 C). Furthermore, the 3D graphene-like cages after removing NVP also serve as a good anode material and deliver a specific capacity of 242.5 mA h g−1 at 0.1 A g−1. The full SIB using these two cathode and anode materials delivers a high specific capacity (109.2 mA h g−1 at 0.1 A g−1) and good cycling stability (77.1% capacity retention over 200 cycles at 0.1 A g−1).

Tin-based nanomaterials have been extensively explored as high-capacity anode materials for lithium ion batteries (LIBs). However, the large volume changes upon repeated cycling always cause the pulverization of the electrode materials. Herein, we report the fabrication of uniform SnS2@C hollow microspheres from hydrothermally prepared SnO2@C hollow microspheres by a solid-state sulfurization process. The as-prepared hollow SnS2@C microspheres with unique carbon shell, as electrodes in LIBs, exhibit high reversible capacity of 814 mA h g−1 at a current density of 100 mA g−1, good cycling performance (783 mA h g−1 for 200 cycles maintained with an average degradation rate of 0.02% per cycle) and remarkable rate capability (reversible cap-abilities of 433 mA h g−1 at 2 C). The hollow space could serve as extra space for volume expansion during the charge-discharge cycling, while the carbon shell can ensure the structural integrity of the microspheres. The preeminent electrochemical performances of the SnS2@C electrodes demonstrate their promising application as anode materials in the next-generation LIBs.锡基材料作为锂离子电池高容量负极材料得到了广泛研究. 然而循环充放电过程中的大体积变化通常会造成电极材料粉化. 本文报道了水热法合成SnO2@C空心微米球, 再对其进行固相硫化制备SnS2@C空心微米球的方法. 制得的SnS2@C空心微米球具有独特的碳外壳及空心结构, 用作锂离子电池电极材料时, 在100 mA g-1电流密度下表现出814 mA h g−1的高可逆容量, 优秀的循环性能(循环200圏后仍保留783 mA h g−1, 平均每圏损失0.02%), 以及出色的倍率容量(2 C时为433 mA h g−1). 其内部空心部分可为充放电循环过程中的体积膨胀提供额外空间, 同时碳外壳能够保护微米球的完整性. 该SnS2@C出色的电化学性能展示出用于下一代锂离子电池负极材料的应用前景.

Carbonaceous composite materials have been extensively studied in energy storage and conversion devices and commonly are fabricated from liquid precursors. In this work, we reported an unusual formation of vanadium oxide and carbon nanocomposite from microsized VO2 microspheres through a “dissolution and recrystallization” process with the assistance of LiH2PO4. The obtained vanadium oxides nanoparticles are in uniform distribution in the carbon matrix. The V2O3/carbon composite inherits the porous feature of the Ketjen black (KB) carbon and has a surface area of 76.59 m2 g−1. As an anode material for lithium/sodium-ion batteries, the V2O3/carbon nanocomposites exhibit higher capacity, better rate capability and cycling stability than the V2O3 nanoparticle counterparts. The enhanced electrochemical performances are attributed to the porous V2O3/carbon nanocomposites, which can allow the electrolyte penetration, shorten the ion diffusion distance and improve the electronic conductivity.碳复合材料已经在能量储存和转换设备中得到广泛的研究, 并且通常由液体前驱体制备. 本文报道了在LiH2PO4的帮助下, VO2微米球通过“溶解和重结晶”, 形成V2O3和碳纳米复合材料的特殊过程. 得到的钒氧化物纳米颗粒在碳基体中分布均匀. V2O3/碳复合材料继承了KB碳的多孔特征, 比表面积为76.59 m2g−1. 作为锂/钠离子电池的负极材料, V2O3/碳复合材料表现出比V2O3纳米颗粒更高的放电比容量, 更好的倍率性能和循环稳定性. 电化学性能提高归因于V2O3/碳纳米复合材料的多孔结构, 其允许电解质渗透, 缩短离子扩散距离并提高电子导电率.

Hollow structures with complex interiors are promising to endow electroactive materials with fascinating physical properties, such as low mass density, large surface area and high permeability. Meanwhile, the construction of hollow structures with binary chemical compositions could further enhance the resultant electrochemical properties. Herein, we reported a designed synthesis of multi-shelled CoO/Co9S8 hollow microspheres by calcining a hollow microsphere precursor with S powder in argon gas (Ar). The inherent characteristic of cobalt(II) mono-oxide can benefit the electrochemical activity, while the cobalt sulfide component could improve the electrical conductivity of this cobalt-based composite material. These multi-shelled hollow structures are proved to possess a porous texture with a relatively large specific surface area (SSA = 43.1 m2 g−1), which could provide more active sites for electrochemical reactions. As a result, the as-prepared multi-shelled CoO/Co9S8 hollow microspheres exhibit an enhanced specific capacitance and excellent rate performance when evaluated as electrode materials for hybrid supercapacitors.

In this work, nitrogen-doped, yolk–shell-structured CoSe/C mesoporous dodecahedra are successfully prepared by using cobalt-based metal–organic frameworks (ZIF-67) as sacrificial templates. The CoSe nanoparticles are in situ produced by reacting the cobalt species in the metal–organic frameworks with selenium (Se) powder, and the organic species are simultaneously converted into nitrogen-doped carbon material in an inert atmosphere at temperatures between 700 and 900 °C for 4 h. For the composite synthesized at 800 °C, the carbon framework has a relatively higher extent of graphitization, with high nitrogen content (17.65%). Furthermore, the CoSe nanoparticles, with a size of around 15 nm, are coherently confined in the mesoporous carbon framework. When evaluated as novel anode materials for sodium ion batteries, the CoSe/C composites exhibit high capacity and superior rate capability. The composite electrode delivers the specific capacities of 597.2 and 361.9 mA h g–1 at 0.2 and 16 A g–1, respectively.Keywords: anode; cobalt selenide; metal−organic frameworks; nitrogen-doped carbon; sodium ion batteries;

Due to limited Li resources, sodium-ion batteries (NIBs) have become promising candidates for application in large-scale energy storage systems, and the development of high-performance anode materials for NIBs has become particularly urgent. Moreover, sodium-ion capacitors (NICs), which combine the characteristics of batteries and capacitors, have attracted significant research interest due to their high energy and power density. Herein, we report the design of efficient hydrothermal routes for synthesizing interlaced Sb2O3 nanosheets and Sb2S3 micro-nanospheres, grown on carbon fiber cloth, referred to as SO/CFC and SS/CFC, respectively, which were then used as flexible electrodes for NIBs and NICs devices. For NIBs applications, the SO/CFC electrodes exhibit a high stable capacity of 514 mA h g−1 after 500 cycles at 0.5 A g−1. The SS/CFC electrodes also display a stable capacity of 736 mA h g−1 after 650 cycles at 0.5 A g−1 and the high-rate capability can reach a high current density of 15 A g−1. Importantly, the flexible NIC device based on SO/CFC or SS/CFC as the anode and carbon fibers as the cathode was demonstrated, which manifests high power density and energy density, as well as significantly superior cycle stability.

Olivine-type structured LiMnPO4 has been extensively studied as a high-energy density cathode material for lithium-ion batteries. However, preparation of high-performance LiMnPO4 is still a large obstacle due to its intrinsically sluggish electrochemical kinetics. Recently, making the composites from both active components has been proven to be a good proposal to improve the electrochemical properties of cathode materials. The composite materials can combine the advantages of each phase and improve the comprehensive properties. Herein, a LiMnPO4·Li3V2(PO4)3/C composite with interconnected nanorods and nanoflakes has been synthesized via a one-pot, solid-state reaction in molten hydrocarbon, where the oleic acid functions as a surfactant. With a highly uniform hybrid architecture, conductive carbon coating, and mutual cross-doping, the LiMnPO4·Li3V2(PO4)3/C composite manifests high capacity, good rate capability, and excellent cyclic stability in lithium-ion batteries. The composite electrodes deliver a high reversible capacity of 101.3 mAh g–1 at the rate up to 16 C. After 4000 long-term cycles, the electrodes can still retain 79.39% and 72.74% of its maximum specific discharge capacities at the rates of 4C and 8C, respectively. The results demonstrate that the nanorod-nanoflake interconnected LiMnPO4·Li3V2(PO4)3/C composite is a promising cathode material for high-performance lithium ion batteries.Keywords: cathode materials; hybrid nanostructure; LiMnPO4·Li3V2(PO4)3/C; lithium-ion batteries; phosphates

Carbon-based nanocomposites have been extensively studied in energy storage and conversion systems because of their superior electrochemical performance. However, the majority of metal oxides are grown on the surface of carbonaceous material. Herein, we report a different strategy of constructing V2O5 within the metal organic framework derived carbonaceous dodecahedrons. Vanadium precursor is absorbed into the porous dodecahedron-shaped carbon framework first and then in situ converted into V2O5 within the carbonaceous framework in the annealing process in air. As cathode materials for lithium ion batteries, the porous V2O5@C composites exhibit enhanced electrochemical performance, due to the synergistic effect of V2O5 and carbon composite.

•A sandwich-structured LVP/C is prepared by a facile soft chemistry route.•MOF-derived nitrogen-doped carbon is used to improve the conductivity.•The structure can accommodate volume changes in repeated cycles in LIBs.•The LVP/C shows excellent rate capability and long-term cycling stability.A sandwich-structured Li3V2(PO4)3/carbon (LVP/C) composite has been facilely prepared through a soft chemistry route and its electrochemical performance has been investigated. The conductivity of the electrode material can be greatly improved by the introduction of metal–organic frameworks (MOFs) derived nitrogen-doped carbon, leading to its superior rate performance in lithium ion batteries. The carbon particles with diameters of 200–300 nm are uniformly dispersed in the composite. Meanwhile, the interconnected carbon particles form a carbon matrix surrounding the LVP flakes, constructing a sandwich-like structure. This structure provides ample space for accommodating the volume change of LVP during repeated cycles, and highly improves the electronic conductivity of the composites. Thanks to this, high capacity retention can be attained in ultralong cycles (83% after 2500 cycles) at high rate (5C).

•Uniform 8LiFePO4·Li3V2(PO4)3/C nanoflakes were synthesized by a solid-state reaction in molten hydrocarbon.•The nanoflakes exhibit superior electrochemical performance as cathode materials for lithium-ion batteries.•The enhanced performances were attributed to the unique nanostructures and mutual doping effect.The synthesis of novel nanostructures at high temperatures is a big challenge because of the particle growth and aggregations. In particular, the fabrication of two active components with uniform structures is rarely reported. Herein, uniform 8LiFePO4·Li3V2(PO4)3/C nanoflakes have been synthesized by a one-pot, solid-state reaction in molten hydrocarbon, where the oleic acid functions as a surfactant. The composite components of LiFePO4 and Li3V2(PO4)3 are distributed homogenously within the nanoflakes. Moreover, the nanoflakes are coated by in-situ generated carbon from oleic acid during the sintering process in H2/Ar. The as-prepared 8LiFePO4·Li3V2(PO4)3/C nanoflakes are approximately 20–50 nm in thickness and are stacked together to construct a porous structure, which have a surface area of 30.21 m2 g−1. The lithium ion diffusion coefficient can be greatly improved by making 8LiFePO4·Li3V2(PO4)3/C composite. As cathode material for lithium ion batteries, the as-prepared material exhibits excellent electrochemical performances, including high reversible capacity, good cyclic stability and rate capability. The composite electrode delivers a high capacity of 161.5 mAh g−1 at 0.1C, which is very close to the theoretical capacity. Even at 10C, the electrode can deliver a specific discharge capacity of 118.6 mA h g−1. After the long-term 1000 cycles, the electrodes can still retain 93.21% and 88.7% of its maximum specific discharge capacities at the rates of 2C and 5C, respectively. The results demonstrate the 8LiFePO4·Li3V2(PO4)3/C nanoflakes are promising cathode materials for high-performance lithium ion batteries.

Hollow structured metal oxides are extensively studied in energy storage and conversion systems. In this work, we report the fabrication of multi-shelled Fe2O3 microspheres with nanospindles assembly on its exterior shell. The β-FeOOH precursor nanospindles were firstly grown on the surface of carbon microspheres to produce β-FeOOH@carbon composites, which were later converted into multi-shelled Fe2O3 microspheres by calcination in air. As electrode material for supercapacitors, the multi-shelled Fe2O3 microspheres exhibit high capacity and good rate capability. The electrode delivers the specific capacitances of 630 and 510 F g−1 at the current densities of 1 and 5 A g−1, respectively.中空结构的金属氧化物在能源储存和转化系统中已被广泛研究. 本文报道了纳米纺锤自组装的多层中空α-Fe2O3微米球. β-FeOOH前 驱体纳米锤首先在炭球表面沉积生长得到β-FeOOH@炭球复合材料, 然后在空气中烧结移除模板, 转变为多层中空α-Fe2O3微米球. 该材料 用作超级电容器的电极材料具有高容量和良好的倍率性能. 该电极在1 和5 A g−1的条件下, 可以释放630和510 F g−1的比放电容量.

In this work, hollow structured V2O5 microspheres were fabricated from solid vanadium precursor microspheres which were prepared by microwave-assisted, solvothermal approach. In the annealing process, the spherical precursor microspheres can be converted into hollow microspheres, serving as a sacrificial template. The synthesis approach is quite different from the previously reported approaches for the preparation of hollow structured V2O5 microspheres. As cathode materials for lithium ion batteries, the hollow-structured V2O5 microspheres exhibit high capacity and good rate capability. The electrodes deliver specific discharge capacities of 132 and 113 mA h g-1 at the current densities of 1 C and 8 C, respectively.本文报道了一种制备V2O5中空微球的新方法. 首先采用微波、 溶剂热法制备了实心结构的钒前躯体, 再在空气中烧结, 实现其向空心结构V2O5微球的结构转变. 在此过程中, 前躯体微球起到了牺牲模板的作用. 该制备方式与之前报道的V2O5中空微球的方法有较大不同. 作为锂离子电池正极材料, 该V2O5中空微球的方法有较大不同. 作为锂离子电池正极材料, 该V2O5微球展现了较高的容量和优异的倍率性能. 该材料在电流密度大小为1 C和8 C下的初始放电比容量分别为132和113 mA h g−1.

•V2O3/KB carbon composite has been fabricated by using porous Ketjen black carbon as templates.•Porous V2O5 is created after removing the KB carbon in the V2O3/KB carbon composite.•The porous V2O5 electrode materials exhibit good electrochemical performance for lithium ion batteries.Similar to carbonaceous materials, porous metal oxides have attracted wide attention in energy storage and conversion systems because of their structural advantages, including high activity and electrolyte accessibility. In this work, we report the novel preparation of porous vanadium pentoxide (V2O5) as high performance cathode material for lithium ion batteries. Ketjen black (KB), a porous carbon material, has been employed as hard templates to host precursor species in their porous structures. The porous V2O5 electrode material is prepared after removing the KB carbon framework by calcinating the composites in air. As cathode materials for lithium ion batteries, the porous V2O5 electrodes exhibit high capacity, good cycling stability and rate capability. An initial discharge capacity of 141.1 mA h g−1 is delivered at a current density of 100 mAg−1, very close to the theoretical capacity of 147 mA h g−1.

•Zn2SnO4 nanoparticles were prepared by facile solvothermal process.•NaHCO3 was firstly used as mineralizer in this process.•Zn2SnO4 showed higher capacity and cycling stability.•Zn2SnO4 showed excellent rate performance.Zn2SnO4 nanoparticles have been prepared by a facile solvothermal process using NaHCO3 as a mineralizer. The Zn2SnO4 nanoparticles with a mean size of 50 nm were obtained after solvothermal treatment at 200 °C for 18 h. SnO2 nano-needles started to appear when the reaction time was extended to 24 h. As anode materials for lithium-ion batteries, the Zn2SnO4 nanoparticles exhibited initial capacities of 1322 and 784 mA h g−1 at the current density of 100 and 300 mA g−1, respectively. The as-prepared Zn2SnO4 nanoparticles showed quite good rate capability.

•The ultra-large VO2 nanosheets with exceptional small thickness were successfully fabricated by a template-free solvothermal method.•The VO2 nanosheets can be safely converted into V2O5 nanosheets with well retained structures.•The V2O5 nanosheets exhibited excellent cyclic stability and remarkable rate capability as cathode materials for lithium ion batteries.•The excellent electrochemical performances were attributed to the layer-by-layer stacking of the ultra-large nanosheets with exceptional small thickness.Similar to graphene, transition metal oxide nanosheets have attracted a lot of attention recently owning to their unique structural advantages, and demonstrated promising chemical and physical properties for various applications. However, the synthesis of transition metal oxide nanosheets with controlled size and thickness remains a great challenge for both fundamental study and applications. The present work demonstrates a facile solvothermal synthesis of ultra-large (over 100 μm) VO2(B) nanosheets with an exceptionally small thickness of only 2–5 nm corresponding to 3–8 layers of (001) planes. It can be readily transferred into V2O5 with well retained nanosheet structures when calcined, which exhibit remarkable rate capability and great cycling stability. Specifically, the as-synthesized vanadium pentoxide nanosheets deliver a specific discharge capacity of 141 mA h g−1 at a current density of 0.1 A g−1, which is 96% of its theoretical capacity (147 mA h g−1) for one Li+ ion intercalation/removal per formular within a voltage window of 2.5–4 V. Even at an extreme-high current density of 5 A g−1, it still can exhibit a high specific discharge capacity of 106 mA h g−1. It is worthy to note that the V2O5 nanosheets electrode can retain 92.6% of the starting specific discharge capacity after 500 discharge/charge cycles at the current density of 1.5 A g−1.

•VO2 (B) nanobelt arrays have been synthesized by a template-free hydrothermal method.•Porous V2O5 nanobelt arrays can be obtained by calcinating the VO2 nanobelt arrays in air.•The V2O5 nanobelt array electrode shows excellent rate capability and cyclic stability in lithium ion batteries.A facile hydrothermal route has been developed to fabricate the metastable VO2 (B) ultra-thin nanobelt arrays, which can be converted into V2O5 porous nanobelt arrays after calcinating VO2 (B) in air at 400 °C for 1 h. The influence of hydrothermal time to the crystallinity and morphology of the VO2 phase has been studied. A possible mechanism for the formation of VO2 nanobelt arrays has been proposed in this paper. As a cathode material for lithium ion batteries, the V2O5 nanobelt arrays show excellent rate capability and cycling stability. An initial discharge capacity of 142 mA h g−1 can be delivered at a current density of 50 mA g−1 with almost no capacity fading after 100 cycles. Even at a current density of 1000 mA g−1, they still exhibit the capacity of 130 mA h g−1 and superior capacity retention capability. The excellent electrochemical properties are attributed to the ultra-thin thickness and the porous structures of the nanobelts.

Two-dimensional (2D) porous hybrid bimetallic transition metal oxide (TMO) nanosheets demonstrated promising applications in the energy field due to their large surface areas, porous structure, and synergistic effects. However, the synthesis of these materials is still a big challenge. In this study, we rationally designed a facile strategy to prepare 2D porous hybrid bimetallic TMO (Co3O4/ZnO) nanosheets with novel structural and electrochemical synergistic effects. Derived from bimetallic MOF nanosheets, the porous hybrid nanosheets possess high surface areas and large pore volume. In particular, they are rich in oxygen vacancies, which provide more active sites for electrochemical reaction. Moreover, the harmonious multi-step conversion reaction between Co3O4 and ZnO was helpful for volume buffering, leading to an outstanding cyclic stability. With remarkable structural features and harmonious electrochemical behaviors, the Co3O4/ZnO hybrids exhibit excellent electrochemical performances as anodes for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). This study also introduces a new strategy to prepare 2D porous hybrid bimetallic TMO nanosheets, which can find wide applications in energy storage, catalysis, sensors, and information storage devices.

Due to limited Li resources, sodium-ion batteries (NIBs) have become promising candidates for application in large-scale energy storage systems, and the development of high-performance anode materials for NIBs has become particularly urgent. Moreover, sodium-ion capacitors (NICs), which combine the characteristics of batteries and capacitors, have attracted significant research interest due to their high energy and power density. Herein, we report the design of efficient hydrothermal routes for synthesizing interlaced Sb2O3 nanosheets and Sb2S3 micro-nanospheres, grown on carbon fiber cloth, referred to as SO/CFC and SS/CFC, respectively, which were then used as flexible electrodes for NIBs and NICs devices. For NIBs applications, the SO/CFC electrodes exhibit a high stable capacity of 514 mA h g−1 after 500 cycles at 0.5 A g−1. The SS/CFC electrodes also display a stable capacity of 736 mA h g−1 after 650 cycles at 0.5 A g−1 and the high-rate capability can reach a high current density of 15 A g−1. Importantly, the flexible NIC device based on SO/CFC or SS/CFC as the anode and carbon fibers as the cathode was demonstrated, which manifests high power density and energy density, as well as significantly superior cycle stability.