表面三维结构构造对磷酸铁锂电化学性能的影响

Construction of three-dimensional conductive network and its electrochemical properties of lithium iron phosphate

电子产品的普及对锂离子电池商业正极材料磷酸铁锂的倍率充放电能力和循环稳定性提出了更高的要求。石墨烯由于其独特的电子共轭态和单原子层结构,具有优越的电子迁移性、大的比表面积和良好的热与化学稳定性,是理想的磷酸铁锂表面结构和功能修饰材料。本文将结合传统材料表面金属包覆的方法,在化学还原氧化石墨烯包覆过程中引入二价金属离子,在磷酸铁锂表面形成三维导电网络的化学还原氧化石墨烯/金属包覆层。实验结果表明,表面三维结构的构造可显著地改善磷酸铁锂的导电性和锂离子扩散性能。

It is challenging to develop lithium iron phosphate（ LiFePO4） possessing simultaneously high rate capability and good cycling stability as lithium ion batteries cathode materials. Graphene sheets,have superior electronic mobility,large surface area,and decent thermal and chemical stability,owing to the unique electronic conjugate state and the single atomic layered morphology,and is considered as the promising material for surface functional modification of LiFePO4. In this work,based on traditional method of surface metal coating,bivalent metal ion is introduced in the process of chemical reduced graphene oxide coating,forming the three-dimensional conducting network of chemical reduced graphene oxide/metal coating layer on the surface of LiFePO4. The results show that the surface three-dimensional structure can improve the conductivity and the diffusion properties of LiFePO4.