研磨及包覆改性石墨抑制金属锂沉积

Preventing lithium deposition by surface modified graphite after grinding and coating

通过机械研磨和碳包覆两种手段,对人造石墨形貌进行改性,采用SEM、Raman、BET对改性前后石墨形貌、表面结构、比表面积进行表征,同时采用EDS和恒流充放电电化学分析方法对负极极片析锂情况、电池放电容量进行分析,结果表明:碳包覆后样品表面变得光滑,石墨化度未影响,表面无序度增加,减少了金属锂析出;碳包覆前增加机械球磨工艺,使一次颗粒粒度减小,缩短锂离子扩散路径,碳包覆改性引入无序碳结构,两种作用协同效应更有效地抑制点状金属锂沉积的发生,同时提升了电池容量。

The morphologies, microstructure and special surface areas of artificial graphite granules with grinding and coating modification were analyzed with the help of SEM,Raman and BET. The lithium plating of the anode was analyzed using EDS, and the discharge capacity of cell was tested by the electrochemical tests. The results show that the surface of the graphite is smooth and the metal lithium deposition is restrained by disordered carbon coating without a significant change in bulk crystallinity. The distance of Li-ion diffusion is shorted by reducing the size of the graphite granules after grinding. The lithium metal plating is prevented and the discharge capacity of the cell is improved by the cooperation effects of grinding and coating.