From Waste to Energy Storage: Fabrication of FVW-Si/G500@C Anode Materials from Photovoltaic Silicon Scrap and Their Enhanced Lithium-Ion Storage Performance

The photovoltaic industry generates a substantial amount of high-purity waste silicon powder during the diamond-wire saw cutting process, which can serve as an environmentally friendly and cost-effective resource for lithium-ion battery recycling. However, its commercial application is hindered by the surface attachment of silicon dioxide, organic substances, metal impurities, as well as its intrinsic drawbacks such as significant volume expansion (>300%) during lithium (de)intercalation and low electronic conductivity. To address these issues, this study first purifies the waste silicon powder and then designs the structure of the composites. Using a simple ball-milling combined with sol-gel method, a core-shell composite material with a carbon-coated two-dimensional conductive network (FVW-Si/G500@C) was synthesized. The two-dimensional conductive network provides sufficient space to accommodate the volume expansion of silicon, while the mesoporous structure on the carbon shell offers a fast transport pathway for Li+, thereby enhancing the electrode kinetics. The prepared FVW-Si/G500@C electrode maintained a high reversible capacity of 951.8 mAh g−1 after 100 cycles at a current density of 0.2 A g−1. Even at a high current density of 1 A g−1, it retained a reversible capacity of 230.4 mAh g−1. The results indicated that the synergistic effect between graphite sheets and the mesoporous carbon shell significantly improved the rate performance and cycling stability of the FVW-Si/G500@C electrode. This study provided a theoretical foundation for the scalable, green, and high-value utilization of waste silicon powder in the photovoltaic industry and offered technical support for sustainable energy development.