The Size Effects of Si Particles on the Final Si@C Composite Anode

The particle size of Si raw materials is closely related with the stability and the cost of the final Si-based anode. Nevertheless, the detailed mechanism is still unclear. In the present study, Si particles with different sizes (100 and 500 nm and 1 μm) were used to prepare a nanoporous Si@C (P–Si–C) anode via Si–Mg alloy intermediate and carbon coating with Mg reduction of CO2. Contrary to the general idea, we found that P–Si–C synthesized with larger particle size of silicon exhibited better performance, and P–Si–C (1 μm) could maintain a specific capacity of 1741.1 mAh/g after 70 cycles at a current density of 0.5 A/g, with a capacity retention rate of 81.2%. It enlightens us that silicon–carbon composites can be prepared with low-cost large-grained silicon, which has significant guidance for industrial applications.