磷酸钒盐在水系锌离子电池中的应用

Application of vanadium phosphate in aqueous zinc-ion batteries

  • 摘要: 锂离子电池因锂资源储量有限、分布不均及一定的安全问题,导致其在大型储能领域的应用受限。水系锌离子电池因其资源丰富、安全环保、易于组装以及价格低廉等优势在大规模储能领域具有极大前景。但是由于锌离子与正极材料基体具有较强的静电吸附作用,导致其动力学缓慢以及部分正极材料在水系电解液中存在溶解等问题,限制了水系锌离子电池的发展。在目前的正极材料中,磷酸钒盐因其结构稳定、电压平台高、功率密度高等特点受到研究者的关注。然而,磷酸钒盐作为水系锌离子电池正极材料时,较差的电子电导率和溶解问题,制约其循环稳定性和倍率容量。本文综述各类磷酸钒盐及其衍生物的物相结构、合成方法、储锌性能和储锌机制,归纳提高电化学性能的方法如构建纳米结构、调节电子结构、包覆导电材料、调控电解液等。最后,总结了磷酸钒盐储锌正极材料现阶段存在的挑战,并对其未来的发展方向提出了展望。

     

    Abstract: With the increasing shortage of petroleum resources and serious environmental pollution, the demand for green technology development is growing stronger. Electrical energy storage is an excellent way to store intermittent clean energy and transport clean energy from one place to another. The lithium-ion battery (LIB) is broadly recognized as the first choice for electrical energy storage due to its high energy density, especially in smart electronics and electric cars. Nevertheless, the application of LIB in large-scale energy storage has been limited by various factors, including the limited and uneven distribution of lithium resources, safety issues and toxic organic electrolytes. The aqueous zinc-ion battery (AZIB) has been regarded as a potential substitute for LIB in large-scale energy storage devices because of the competitive theoretical volumetric capacity (5855 mA·h·cm−3) and gravimetric capacity (820 mA·h·g−1) of the Zn anode, the low electrochemical potential of Zn2+ (−0.76 V vs SHE), and the high ionic conductivity of the aqueous electrolyte, the ease of manufacturing (e.g., manufacture in an open-air environment), and the merits of rich resources, low cost and high safety. Finding a cathode material with high energy density and power density is proposed as a strategy to accelerate the progress of AZIB because the cathode material largely dominates the electrochemical properties and the cost of the battery. However, the strong electrostatic interaction between Zn2+ and the host material results in sluggish reaction kinetics, leading to inferior cycling performance and rate property. Some cathode materials are dissolved in aqueous electrolytes, which restrict the development of AZIB. In comparison to the reported AZIB cathodes, including vanadium-based materials, manganese-based materials, Prussian blue analogs, and organic materials, vanadium phosphates have received a lot of attention as cathodes due to their stable structures, high voltage plateaus, and high power densities. This review presents an overview of various vanadium phosphates such as Li3V2(PO4)3, Na3V2(PO4)3, VOPO4, Na3V2(PO4)2F3, NaVPO4F and their derivatives that are applied as cathodes for AZIB. The summary includes their phase structures, synthetic methods, electrochemical performance, electrochemical Zn2+ storage mechanisms and existing problems. The two major challenges in using vanadium phosphates as cathode materials for AZIB are low electronic conductivity and material dissolution problems, both of which result in inferior cycling performance and rate capacity. The resolution strategies for the mentioned challenges include designing the nanostructure, adjusting the electronic structure, coating with conductive materials, and regulating electrolytes to enhance electrochemical properties. Experimental techniques for studying electrochemical mechanisms are also proposed. Finally, the prospects for the future development of these cathodes in AZIB are advanced. It can be expected that this review has some significance for the development of new vanadium phosphates as cathode materials.

     

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