锂离子电池用Si/针状焦复合负极材料的改性及其电化学性能

Modification and Electrochemical Performance of Si/Needle Coke as Anode Material for Lithium Ion Batteries

以石墨化针状焦为原料,采用机械球磨和化学气相沉积法（CVD）制得碳/Si/针状焦复合负极材料。结合XRD、SEM分析手段和电化学特征,研究发现：当石墨化针状焦复合20%的纳米Si后,其首次放电容量高达1110mAh/g,但25次循环后放电容量衰减为200mAh/g;采用CVD方法,在Si/针状焦复合材料的表面沉积厚度为6~8nm的碳后,其首次库伦效率为81%,25次循环后放电容量仍能稳定在860mAh/g,且循环效率接近99%。

Carbon/Si/needle coke composite anode material was prepared from graphitized needle coke by using ball-milling and chemical vapor deposition （CVD） method.According to the analysis of XRD,SEM and relative electrochemical performances,the first discharge capacity of Si/needle coke composite electrode obtained 1110mAh/g if nano Si was added with a weight ratio of 20%,but the discharge capacity reduced to 200mAh/g after 25 cycles.When the carbon was deposited on the surface of Si/needle coke composite with a thickness of 6～8nm by CVD,the first coulomb efficiency was 81% and the discharge capacity can still remain at 860mAh/g even if it was charge/discharged for 25 cycles.