锂离子电池用石墨类负极材料结构调控与表面改性的研究进展

Research Progress on Structure Regulation and Surface Modification of Graphite Anode Materials for Lithium Ion Batteries

锂离子电池作为新一代绿色能量储存和转换装置,具有广阔的应用前景和巨大的经济价值。负极材料是锂离子电池的核心部件之一,其结构和性质对电池的性能起着关键性作用。在众多碳基负极材料中,石墨类材料是目前商业化锂离子电池中应用最广的负极材料。但石墨类负极材料存在可逆容量较低、离子扩散动力学和电解液兼容性较差、体积膨胀率较高等问题,导致锂离子电池的能量密度、大电流倍率性能及循环稳定性等受到严重限制。尤其是近年来新能源汽车对续航里程和快速充放电能力的需求不断提高,使得石墨类负极材料在能量密度与功率密度方面的缺陷日渐凸显。为改善现有石墨类负极材料某些方面的缺陷,提高其综合性能,研究者们主要从石墨类负极材料的表面包覆、化学修饰、元素掺杂和微晶结构优化等角度进行了广泛探究,并取得了丰硕的成果。主要体现在:(1)表面包覆,构筑核壳结构,改善负极材料与电解液的兼容性;(2)化学修饰,调控界面化学性质,增强负极材料表面SEI膜(电极/电解液界面膜)的稳定性;(3)元素掺杂,调节石墨微晶表面的电子状态和导电性,强化负极材料的嵌-脱锂行为;(4)微晶结构优化,修筑三维(3D)梯级纳米孔道,改善锂离子的传输路径,提高负极材料的储能容量和倍率性能。本文简要介绍了锂离子电池的工作原理和其对石墨类负极材料的要求,重点综述了石墨类负极材料在结构调控与表面改性等方面的最新研究进展,并对石墨类负极材料的未来发展趋势进行了展望,以期为高性能锂离子电池用新型碳基负极材料的研发与推广应用提供参考。

Lithium ion batteries(LIBs),which are new generation of green energy storage and conversion devices,have wide application and huge economic value.The performance of LIBs is determined by many factors with one of them being the type of anode material.Specifically,the microstructure and surface properties of the anode play a significant role in determining the performance for the battery.Among all reported carbon-based anode materials,graphite materials are the most widely used for commercial LIBs.However,the inherent disadvantages of graphite anode materials such as low reversible capacity,poor ion diffusion dynamics and electrolyte compatibility as well as high volume expansion prevent further improvement on the energy density,high current multiplier performance and cycle stability for LIBs.Therefore,it is desirable to improve the properties of graphite anode materials in order to produce high performance LIBs.Many research efforts have been made to modify the graphite anode through surface coating,chemical modification,element doping and microcrystalline structure optimization.The main methods are:ⅰ.using surface coating to build core-shell construction,and improve the compatibility between anode mate-rials and electrolyte;ⅱ.using chemical modification to control interface chemical properties,enhance the stability of SEI film(electrode/electrolyte interface film)on the surface of negative electrode material;ⅲ.doping other element in materials to adjust the electronic state and electrical conductivity of graphite microcrystalline surface,and strengthen the behavior of lithium-ion s intercalation and deintercalation of anode materials;ⅳ.optimizing microcrystalline structure to build 3D cascade nanometer channels,improve the transmission path of lithium ions,and improve the energy storage capacity and rate capability of anode materials.In this paper,the current research status and development of graphite anode materials in structural regulation and surface modification are reviewed and the development trend of such anode materials is prospected.This short review is expected to provide some guidance for the development of new carbon-based anode materials,particularly graphite based materials,for high-performance LIBs.