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

HighlightsUtilizing photovoltaic diamond wire saw cutting silicon kerf waste as raw material to achieve a high-value resource recycling, offering both environmental benefits and low-cost advantages.Through a simple ball-milling and sol-gel method, a core–shell composite structure featuring “carbon shell coating + graphite two-dimensional conductive network” (FVW-Si/G500@C) was designed and constructed, effectively addressing the two critical challenges of silicon volume expansion and poor electrical conductivity.The as-prepared anode material delivered a high reversible capacity of 951.8 mAh g−1after 100 cycles at 0.2 A g−1, and retained a capacity of 230.4 mAh g−1even at a high current density of 1 A g−1, demonstrating significantly enhanced rate capability and cycling stability.What are the main findings?Photovoltaic waste silicon powder features high purity, high tap density, and low specific surface area, enabling direct use as high-capacity anode precursor after simple purification.Optimized ball-milling speed (500 rpm) uniformly anchors silicon particles on graphite flake surfaces, inhibiting agglomeration and constructing a continuous two-dimensional conductive network that enhances electron transport efficiency.RF resin-derived carbon shell provides complete coating, effectively buffering silicon volume expansion and suppressing excessive SEI film growth, substantially improving cycle life and initial Coulombic efficiency.Synergistic effect between graphite conductive network and carbon shell mechanical constraint endows the composite with high capacity, high-rate capability, and long-term cycling stability.What are the implications of the main findings?Provides a feasible pathway for high-value utilization of photovoltaic silicon waste: Industrial waste can be directly converted into high-performance anode materials without complex purification or nanofabrication.Proposes a low-cost, scalable strategy for preparing silicon–carbon anodes: Conventional ball milling and RF resin coating replace high-cost processes such as CVD and template etching, lowering production barriers and advancing commercialization.Deepens understanding of structural design principles for silicon–carbon composites: Reveals the synergistic mechanism of the “two-dimensional conductive network + elastic carbon shell” dual-constraint structure, offering insights for rational design of high-performance silicon-based anodes.Aligns with green manufacturing and sustainable development: Reduces photovoltaic solid waste at the source while providing low-environmental-footprint raw materials for lithium-ion batteries, delivering both ecological and economic benefits.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−1after 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.