石墨烯基电极材料结构设计及其在二次电池中的应用

Structure design of graphene based electrode materials and its application in secondary battery

电极是实现高效电化学储能的基础,而常规的电极大多采用半导体甚至绝缘体为活性材料,不仅存在导电性差、电化学利用率低、倍率性能差等问题,而且部分电极材料在反应过程中还存在体积膨胀严重、中间产物流失等缺点,导致电极循环稳定性差.解决这些问题的有效途径之一是从电极材料的微纳结构入手,设计兼具高电化学活性及高结构稳定性的材料.石墨烯具有优异的导电性、超高的比表面积、柔性的二维结构及良好的机械性能,可用于构建高性能复合电极.石墨烯基电极材料结构主要包括核壳结构、三维网络结构、多级孔结构、三明治结构等,这些结构均对电化学储能器件的性能有不同程度的提升.本文以结构设计为主线总结了石墨烯在二次电池(如锂离子电池、锂硫电池和锂空气电池)电极材料结构设计中的应用,分析了不同结构类型在改善电化学性能方面的优势,为提高电化学储能体系的性能带来启示.

Electrode is the foundation of high efficient electrochemical energy storage. The conventional electrode materials mostly adopt semiconductor or insulator as active materials, which always suffer from poor electrical conductivity, low electrochemical efficiency and poor rate performance. What＇s worse, some of the electrode materials undergo large volume expansion and intermediates dissolvent during electrochemical reaction, which leads to a poor cycling stability. Designing electrode materials with micro-nano structure is an effective way to solve these problems and ensure the electrode with high electrochemical activity and high structure stability. Graphene possesses a flexible two-dimensional structure, high conductivity, huge specific surface area and great mechanical strength. Thus, it is expected to be an ideal functional material for designing high performance composite electrode. The structure model of graphene based electrode materials mainly includes core-shell structure, three-dimensional network structure, hierarchical porous structure and sandwich structure, etc. These structures could improve the performance of electrochemical energy storage devices to a certain extent. In this review, we will summarize the application of graphene in secondary battery（such as lithium-ion battery, lithium-sulfur battery and lithium-air batteries） based on structure design, as well as analyze the advantages of different structure types in improving the electrochemical performance, which will bring some revelations to improve the performance of electrochemical energy storage system.