Modification of graphite anode with low-content micro-Si for enhanced rate capability

Graphite anode materials have advantages such as high charge and discharge efficiency, a low lithium intercalation potential, and good safety, and have been widely applied in the field of new energy. However, their relatively low specific capacity and limited rate performance make it difficult to meet current market demand in the new energy sector. In this paper, commercial graphite and micron-sized silicon were used as raw materials. After dispersed in isopropyl alcohol, they were physically combined in a ball mill at a ball-to-material ratio of 5:1 and a rotational speed of 240 r/min. The influence of the mass ratio of graphite to silicon on the performance of the composite materials was investigated. When the mass ratio of the two materials was 19:1, the obtained 5%-mSi/Gr anode delivered an initial discharge specific capacity of 428.86 mAh/g with an initial coulombic efficiency of 80.77%, at a current density of 0.3 C. At a current density of 0.5 C, the discharge specific capacity was 302.94 mAh/g after 200 cycles, with a capacity retention rate of 75.91%, which is significantly higher than that of the conventional graphite anode (29.32%). These results show that introducing a low content of micron-sized silicon into the graphite anode, not only increases the overall specific capacity of the material to a certain extent, but also effectively improves the rate performance of the graphite anode. This work provides an experimental reference for improving the rate performance of low-cost graphite anodes for lithium-ion batteries.