Upcycling of long-term Si/C composites by introducing interfacial chemical bonds from spent solar photovoltaic and lithium-ion batteries

Recycling spent solar photovoltaic modules (PV) and lithium-ion batteries (LIBs) is crucial due to their environmental and economic importance. However, the current methods—recycling Si from panels as Si ingots and treating graphite as degraded material—offer limited economic returns. Inspired by Si/C composites for LIBs, a strategy for upcycling of long-term Si/C composites from spent PV panels and LIBs has been developed. Particularly, by introducing recycled ethylene vinyl acetate (EVA) from PV as a binding agent, interfacial Si–C bonds were effectively established, leading the as-optimized sample to overcome siliconization of the existing physically mixed Si/C composites by improving structural stability and reducing volume change. More detailed kinetic analysis revealed that the developed strategy enhanced diffusion coefficients and reduced internal resistances, particularly the interfacial ion migration in Si/C composites, leading to excellent electrochemical properties. Specifically, it displays a considerable capacity of 967 mAh g⁻¹ at 1.0 A g⁻¹, with a retention ratio of ∼77.6% after 200 cycles. Moreover, the full cell displayed an initial capacity of 1178.1 mAh g⁻¹, which could be maintained at approximately 821.2 mAh g⁻¹ after 50 cycles. The promising upcycling strategy yielded considerable economic benefits and provides a comprehensive solution for recycling spent PV and LIBs into high-performance Si/C composites.