钴基双金属氧化物的制备及其在电化学储能领域的应用

钴基双金属氧化物MCo₂O₄（M=Ni、Zn、Mn等）既继承了单一钴金属氧化物（Co₃O₄、CoO等）高比容量的优点,又引入了新的改性金属元素用于改善其导电性差、倍率性能不佳等缺点,是一种潜在的新型电化学储能材料。本文分类介绍了NiCo₂O₄、ZnCo₂O₄、MnCo₂O₄等钴基双金属氧化物及其复合物的现有研究（包括制备方法、形貌结构、颗粒尺寸及其电化学性能）,阐述了改性手段的可能性机理,并对钴基双金属氧化物后续研究提出了一些看法。     

钴基双金属氧化物的制备及其在电化学储能领域的应

钴基双金属氧化物MCo₂O₄（M=Ni、Zn、Mn等）既继承了单一钴金属氧化物（Co₃O₄、CoO等）高比容量的优点,又引入了新的改性金属元素用于改善其导电性差、倍率性能不佳等缺点,是一种潜在的新型电化学储能材料。本文分类介绍了NiCo₂O₄、ZnCo₂O₄、MnCo₂O₄等钴基双金属氧化物及其复合物的现有研究（包括制备方法、形貌结构、颗粒尺寸及其电化学性能）,阐述了改性手段的可能性机理,并对钴基双金属氧化物后续研究提出了一些看法。     

Fe3O4 anodes for lithium batteries: Production techniques and general applications

Iron oxides, such as Fe₃O₄, are putative anode materials for rechargeable lithium-ion batteries (LIBs). LIBs are extensively used as power sources for electronics. They typically consist of cells, with each cell built out of a lithium cathode and a graphite anode. However, graphite anodes suffer from the disadvantages of significant density, large volume, low energy density, and inferior safety levels. Iron oxides seem to be a promising substitute to the currently used graphite anodes due to their high capacity, extensive availability, good stability, and environmental tolerance. Nevertheless, several hurdles prevent their market expansion, such as inferior electronic/ionic conductivity, large volume changes, poor cycling performance, and low coulombic efficiency. Using Fe₃O₄ seems to be one alternative to address these challenges. This review will cover the current state of development of iron oxide electrodes with respect to design, production techniques, and general applications.     

Calcination-Free Synthesis of Well-Dispersed and Sub-10 nm Spinel Ferrite Nanoparticles as High-Performance Anode Materials for Lithium-Ion Batteries: A Case Study of CoFe2O4

Spinel ferrites are promising anode materials for lithium-ion batteries (LIBs) owing to their high theoretical specific capacities. However, their practical application is impeded by inherent low conductivity and severe volume expansion, which can be surpassed by increasing the surface-to-volume ratio of nanoparticles. Currently, most methods produce spinel ferrite nanoparticles with large size and severe aggregation, degrading their electrochemical performance. In this study, a low-temperature aminolytic route was designed to synthesize sub-10 nm CoFe₂O₄ nanoparticles with good dispersion through carefully exploiting the reaction of acetates and oleylamine. The performance of CoFe₂O₄ nanoparticles obtained by a traditional co-precipitation method was also investigated for comparison. This work demonstrates that CoFe₂O₄ nanoparticles synthesized by the aminolytic route are promising as anode materials for LIBs. Besides, this method can be extended to design other spinel ferrites for energy storage devices with superior performance by simply changing the starting material, such as MnFe₂O₄, MgFe₂O₄, ZnFe₂O₄, and so on.     

Few-Layer MoS2 Nanosheets Encapsulated in N-Doped Carbon Hollow Spheres as Long-Life Anode Materials for Lithium-Ion Batteries

Two-dimensional molybdenum disulfide (MoS₂) has been recognized as a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity, but its rapid capacity decay owing to poor conductivity, structure pulverization, and polysulfide dissolution presents significant challenges in practical applications. Herein, triple-layered hollow spheres in which MoS₂ nanosheets are fully encapsulated between inner carbon and outer nitrogen-doped carbon (NC) were fabricated. Such an architecture provides high conductivity and efficient lithium-ion transfer. Moreover, the NC shell prevents aggregation and exfoliation of MoS₂ nanosheets and thus maintains the integrity of the nanostructure during the charge/discharge process. As anode materials for LIBs, the C@MoS₂@NC hollow spheres deliver a high reversible capacity (747 mA h g⁻¹ after 100 cycles at 100 mA g⁻¹) and excellent long-cycle performance (650 mA h g⁻¹ after 1000 cycles at 1.0 A g⁻¹), which confirm its potential for high-performance LIBs.     

Three-Dimensional Carbon Framework Anchored Polyoxometalate as a High-Performance Anode for Lithium-Ion Batteries

Recently, it has become very important to develop cost-effective anode materials for the large-scale use of lithium-ion batteries (LIBs). Polyoxometalates (POMs) have been considered as one of the most promising alternatives for LIB electrodes owing to their reversible multi-electron-transfer capacity. Herein, Keggin-type [PMo₁₂O₄₀]³⁻ (donated as PMo₁₂) clusters are anchored onto a 3D microporous carbon framework derived from ZIF-8 through electrostatic interactions. The PMo₁₂ clusters can be immobilized steadily and uniformly on the carbon framework, which provides enhanced electrical conductivity and high stability. Compared with PMo₁₂ itself, the as-prepared novel 3D Carbon-PMo₁₂ composite displays a significantly improved Li-ion storage performance as an LIB anode, with excellent reversible specific capacity and rate capacity, as well as high cycling performance (discharge capacity of 985 mA h g⁻¹ after 200 cycles), which are superior to other POM-based anode materials reported so far. The high performance of the Carbon-PMo₁₂ composite can be attributed to the 3D conductive network with fast electron transport, high ratio of pseudocapacitive contribution, and evenly distributed PMo₁₂ clusters with reversible 24-electron transfer capacity. This work offers a facile way to explore novel LIB anodes consisting of electroactive molecule clusters.     

High reversible capacity and rate capability of ZnCo2O4/graphene nanocomposite anode for high performance lithium ion batteries

A facile and straightforward method was adopted to synthesize ZnCo₂O₄/graphene nanocomposite anode. In the first step, pure ZnCo₂O₄ nanoparticles were synthesized using urea-assisted auto-combustion synthesis followed by annealing at a low temperature of 400 °C. In the second step, in order to synthesize ZnCo₂O₄/graphene nanocomposite, the obtained pure ZnCo₂O₄ nanoparticles were milled with 10 wt% reduced graphene nanosheets using high energy spex mill for 30 s. The ZnCo₂O₄ nanoparticles, with particle sizes of 25–50 nm, were uniformly dispersed and anchored on the reduced graphene nanosheets. Compared with pure ZnCo₂O₄ nanoparticles anode, significant improvements in the electrochemical performance of the nanocomposite anode were obtained. The resulting nanocomposite delivered a reversible capacity of 1124.8 mAh g⁻¹ at 0.1 C after 90 cycles with 98% Coulombic efficiency and high rate capability of 515.9 mAh g⁻¹ at 4.5 C, thus exhibiting one of the best lithium storage properties among the reported ZnCo₂O₄ anodes. The significant enhancement of the electrochemical performance of the nanocomposite anode could be credited to the strong synergy between ZnCo₂O₄ and graphene nanosheets, which maintain excellent electronic contact and accommodate the large volume changes during the lithiation/delithiation process.     

Double-Shelled Hollow SiO2@N-C Nanofiber Boosts the Lithium Storage Performance of [PMo12O40]3−

Polyoxometalates (POMs)-based materials, with high theoretical capacities and abundant reversible multi-electron redox properties, are considered as promising candidates in lithium-ion storage. However, the poor electronic conductivity, low specific surface area and high solubility in the electrolyte limited their practical applications. Herein, a double-shelled hollow PMo₁₂−SiO₂@N−C nanofiber (PMo₁₂−SiO₂@N−C, where PMo₁₂ is [PMo₁₂O₄₀]³⁻, N−C is nitrogen-doped carbon) was fabricated for the first time by combining coaxial electrospinning technique, thermal treatment and electrostatic adsorption. As an anode material for LIBs, the PMo₁₂−SiO₂@N−C delivered an excellent specific capacity of 1641 mA h g⁻¹ after 1000 cycles under 2 A g⁻¹. The excellent electrochemical performance benefited from the unique double-shelled hollow structure of the material, in which the outermost N−C shell cannot only hinder the agglomeration of PMo₁₂, but also improve its electronic conductivity. The SiO₂ inner shell can efficiently avoid the loss of active components. The hollow structure can buffer the volume expansion and accelerate Li⁺ diffusion during lithiation/delithiation process. Moreover, PMo₁₂ can greatly reduce charge-resistance and facilitate electron transfer of the entire composites, as evidenced by the EIS kinetics study and lithium-ion diffusion analysis. This work paves the way for the fabrication of novel POM-based LIBs anode materials with excellent lithium storage performance.     

Facile synthesis of single-crystalline Co<Subscript>3</Subscript>O<Subscript>4</Subscript> cubes as high-performance anode for lithium-ion batteries

Transition metal oxides have great potential as anode for lithium-ion batteries (LIBs), owing to their high theoretical capacity and low cost. However, the poor cycling stability and electron conductivity have limited the widely expected application of transition metal oxides. In this work, highly single-crystalline Co₃O₄ cubes with 400 nm in the average side length are successfully synthesized by a facile hydrothermal method. When used as anode for LIBs, the Co₃O₄ single-crystalline cubes exhibit highly stable and substantial discharge capacities of the amount to 877 mA h g^?1 at 200 mA g^?1 after 110 cycles with remarkable capacity retention of 98%, and 576 mA h g^?1 even at a high rate of 2000 mA g^?1. The scalability of the preparation method and the impressive results achieved here demonstrate the potential for the application to the future development of transition metal oxides anodes. These results suggest that the single-crystalline Co₃O₄ is a promising electrode material for the high-performance energy storage devices.     

Fe2O3锂离子电池负极材料研究进展

Fe2O3锂离子电池负极材料因其具有的高能量密度而备受关注。但Fe2O3电极材料存在的如低导电性、充/放电过程中体积改变导致的循环稳定性差等问题限制其实际应用。介绍了高比表面积、结构稳定以及储锂动力学等因素对锂离子电池负极材料电化学性能的重要影响,综述电极活性材料纳米化、形貌控制和杂原子掺杂对Fe2O3负极材料电化学性能改善的相关研究进展,最后对Fe2O3电极材料的发展前景进行了展望。     

Cascading V2O3/N-doped carbon hybrid nanosheets as high-performance cathode materials for aqueous zinc-ion batteries

In recent years, especially when there is increasing concern about the safety issue of lithium-ion batteries（LIBs）, aqueous Zn-ion batteries（ZIBs） have been getting a lot of attention because of their costeffectiveness, materials abundance, high safety, and ecological friendliness. Their working voltage and specific capacity are mainly determined by their cathode materials. Vanadium oxides are promising cathode materials for aqueous ZIBs owing to their low cost, abundant resources, and multivale...     

A Core–Shell Fe/Fe2O3 Nanowire as a High‐Performance Anode Material for Lithium‐Ion Batteries

The preparation of novel one‐dimensional core–shell Fe/Fe₂O₃ nanowires as anodes for high‐performance lithium‐ion batteries (LIBs) is reported. The nanowires are prepared in a facile synthetic process in aqueous solution under ambient conditions with subsequent annealing treatment that could tune the capacity for lithium storage. When this hybrid is used as an anode material for LIBs, the outer Fe₂O₃ shell can act as an electrochemically active material to store and release lithium ions, whereas the highly conductive and inactive Fe core functions as nothing more than an efficient electrical conducting pathway and a remarkable buffer to tolerate volume changes of the electrode materials during the insertion and extraction of lithium ions. The core–shell Fe/Fe₂O₃ nanowire maintains an excellent reversible capacity of over 767 mA h g^?1 at 500 mA g^?1 after 200 cycles with a high average Coulombic efficiency of 98.6 %. Even at 2000 mA g^?1, a stable capacity as high as 538 mA h g^?1 could be obtained. The unique composition and nanostructure of this electrode material contribute to this enhanced electrochemical performance. Due to the ease of large‐scale fabrication and superior electrochemical performance, these hybrid nanowires are promising anode materials for the next generation of high‐performance LIBs.     

MOF-derived ZnCo2O4/C wrapped on carbon fiber as anode materials for structural lithium-ion batteries

In this work, large area MOF-derived ZnCo₂O₄/C anchored on carbon fiber as high-performance anode materials was fabricated via a facile method and subsequent annealing treatment.     

Protic ionic liquids as electrolytes for lithium-ion batteries

In this work we report for the first time about the use of protic ionic liquids (PILs) as electrolyte for lithium-ion batteries. The electrolyte 1 M LiTFSI in Et₃NHTFSI displays a conductivity comparable to that of aprotic ionic liquids, and electrochemical stability window large enough to allow the realization of LIBs containing LFP as cathode and LTO as anode. The use of this PIL as electrolyte in LIBs allows the realization of devices able to deliver good capacity and promising cycling stability.     

Boosting the photoelectrochemical water oxidation performance of bismuth vanadate by ZnCo2O4 nanoparticles

Due to the involvement of four-electron transfer process at photoanode,water oxidation is the ratelimiting step in water splitting reaction.To settle this dilemma,ZnCo₂ O₄ nanoparticles are combined with BiVO₄ to form a p-n ZnCo₂ O₄/BiVO₄ heterojunction photoanode,which is proved by an input voltage-output current test.The built-in electric field formed within the heterojunction structure promotes the effective separation of elect...     

Effect of PPy/PEG conducting polymer film on electrochemical performance of LiFePO4 cathode material for Li-ion batteries

Rechargeable lithium-ion batteries (LIBs) have been the most commonly used batteries in the portable electronics market for many years. Polypyrrole (PPy) was now investigated as a conducting addition agent to enhance the cathode and anode materials performance in LIBs. Actual development in the synthesis and modification of the most promising cathode materials, LiFePO₄, is described in this mini-review. The main aim of this mini-review is to highlight the effect of PPy based conducting polymer films on the electrochemical efficiency of LiFePO₄ based cathode materials for LIBs summarizing our own research. Influence of the polyethylene glycol (PEG) additive in the PPy coating layer was evaluated. The improved electrochemical performance can be attributed to the enhanced electronic conductivity, higher solubility of ions originating from the electrolyte, higher movability of dissolved Li⁺ ions, and improved structural flexibility resulting from the incorporation of the PPy or PPy/PEG conducting polymer layer. The stabilizing effect of PEG in PPy was reflected in lowered cross-linking and reduced structural defects and, in consequence, in higher specific capacity of PPy/PEG-LiFePO₄ cathodes compared to that of PPy-LiFePO₄ cathodes and bare LiFePO₄ cathodes.     

Construction of three-dimensional crumpled Ni-Co TMOs for electrochemical energy storage

Due to excellent electrochemical performances, mixed transition metal oxides (TMOs) as electrode materials have attracted scholarly attention. However, the issues of volume expansion, unstable structure, and low electrical conductivity have limited their development for lithium battery (LIB). Drawing on the strategy of MOFs derivation synthesis combined with low temperature hydrothermal method, this study successfully synthesized the three-dimensional (3D) NiCo₂O₄@Fe₂O₃ with a flower-like crossing channel and a surface crumpled structure. As anode for LIBs, NiCo₂O₄@Fe₂O₃ exhibits more reliable performance than Ni−Co oxides. Our experiments verified that the Ni−Co composite electrical conductivity and cycling stability were both improved by the Fe₂O₃ coating. Under the high current density of 1000 mA g⁻¹, the capacity decay rate of NiCo₂O₄@Fe₂O₃ tends to be stable after 60 cycles, and the capacity remains at 945 mAh g⁻¹ after 400 cycles. Besides, the specific crossing porous-channel structure mode improved the composite's carrier transport efficiency, and coulombic efficiency reached 100 % after 400 cycles. Noteworthy is the fact that the crumpled surface structure formed by the 2D Ni−Co nanosheets promotes the construction of heterostructures, further enhances the interface capacitance effect, and strengthens the rating capacity.     

MOF-derived Core-Shell CoP@NC@TiO2 Composite as a High-Performance Anode Material for Li-ion Batteries

Transition-metal phosphides have been regarded as promising anode materials for high-energy lithium-ion batteries (LIBs) due to their high capacity and low cost. However, the mechanical pulverization and resultant capacity fade critically limit their further development. Here, we have designed an innovative core-shell CoP@NC@TiO₂ composite with an exotic rhombic dodecahedral morphology derived from ZIF-67 precursor, which combines both advantages from TiO₂ with excellent cycling stability and CoP with high capacity. The additional MOF-derived N-doped carbon framework is considered to improve the electrical conductivity and accommodate the volume expansion of CoP particles. Moreover, the outer TiO₂ shell can also buffer the mechanical stress and maintain the integrity of composite. With the unique structure, the core-shell CoP@NC@TiO₂ composite material exhibits excellent electrochemical performance with a considerable discharge specific capacity of 706.3 mAh g⁻¹ at a current density of 100 mA g⁻¹ after 200 cycles and outstanding rate capacity. Hence, our work demonstrates that this core-shell structure strategy combined with MOF-derived carbon framework could provide a practical pathway towards enhanced electrode materials for energy storage and conversion.     

Hierarchical ZnCo2O4@NiCo2O4 Core–Sheath Nanowires: Bifunctionality towards High‐Performance Supercapacitors and the Oxygen‐Reduction Reaction

Increasing energy demands and worsening environmental issues have stimulated intense research on alternative energy storage and conversion systems including supercapacitors and fuel cells. Here, a rationally designed hierarchical structure of ZnCo₂O₄@NiCo₂O₄ core–sheath nanowires synthesized through facile electrospinning combined with a simple co‐precipitation method is proposed. The obtained core–sheath nanostructures consisting of mesoporous ZnCo₂O₄ nanowires as the core and uniformly distributed ultrathin NiCo₂O₄ nanosheets as the sheath, exhibit excellent electrochemical activity as bifunctional materials for supercapacitor electrodes and oxygen reduction reaction (ORR) catalysts. Compared with the single component of either ZnCo₂O₄ nanowires or NiCo₂O₄ nanosheets, the hierarchical ZnCo₂O₄@NiCo₂O₄ core–sheath nanowires demonstrate higher specific capacitance of 1476 F g^?1 (1 A g^?1) and better rate capability of 942 F g^?1 (20 A g^?1), while maintaining 98.9 % capacity after 2000 cycles at 10 A g^?1. Meanwhile, the ZnCo₂O₄@NiCo₂O₄ core–sheath nanowires reveal comparable catalytic activity but superior stability and methanol tolerance over Pt/C as ORR catalyst. The impressive performance may originate from the unique hierarchical core–sheath structures that greatly facilitate enhanced reactivity, and faster ion and electron transfer.     

锂离子电池片状四氧化三钴负极的合成及改性

采用液相沉淀法结合低温固相热解法合成了锂离子电池片状Co3O4负极.通过X射线粉体衍射(XRD)、Brunauer-Emmett-Teller(BET)比表面积分析、扫描电子显微镜(SEM)及恒电流充放电等表征手段,发现该Co3O4为立方相,结晶完整且无杂质,由直径为1.5-3.0μm、厚度约为100-300 nm的不规则片状颗粒组成,比表面积约为30.5 m2·g-1;其比容量高且容量保持率好,在0.1C倍率下,首次放电容量高达1444.5 mAh·g-1,50次循环后充电容量仍大于1100.0 mAh·g-1;但在高倍率(1C)下,50次循环后充电容量保持率仅为75.3%,倍率性能一般.故采用碳纳米管(CNTs)掺杂改性,结果表明:在1C倍率下,70次循环后复合材料充电容量保持率为96.3%;在2C倍率下,50次循环后充电容量保持率仍高达97.0%,倍率性能显著提升.