Effects of Ball-Milling on Structure and Electrochemical Property of CA-SiO Composite

Carbon aerogel (CA)-SiO with excellent lithium insertion-extraction property could be prepared through ball-milling of carbon aerogel (CA) with SiO. Effects of ball-milling process including ball-milling time and ball-milling speed on structure and electrochemical property of CA-SiO composite were investigated. The results show that ball-milling of amorphous SiO with CA can crystallize Si with small particle size, the crystal size of Si increases with the extension of ball-milling time and the increase of ball-milling speed, and then decreases. The crystallization of Si can be improved by the extension of ball-milling time and the increase of ball-milling speed. However, ball-milling for too long time or at too high speed will result in transformation of crystal Si to amorphous. Little influence of ball-milling time and ball-milling speed is found on crystal size of C in the prepared CA-SiO, though ball-milling leads to some increase of C crystal size. CA-SiO has higher capacity and better cycling stability when the silicon within this material shows higher crystallization and smaller crystal size. In contrast, amorphous Si is disadvantageous for lithium insertion-extraction in CA-SiO which will lead to poorer cycling stability. The ball-milling speed of 400r/min and the ball-milling time of 10h are the best preparation parameters for CA-SiO used as anode material of lithium-ion battery.