Efficient recycling strategy for spent graphite anodes via structural defect repair and interface construction

The burgeoning accumulation of spent graphite from retired lithium-ion batteries (LIBs) necessitates efficient, sustainable upcycling strategies. The failure of spent graphite stems primarily from irreversible solid electrolyte interphase (SEI) accumulation and localized structural disintegration. Herein, we propose an in-situ interfacial reconstruction strategy using polyacrylonitrile as a carbon precursor to synchronously repair lattice defects and bridge fractured edges. The reconstructed interface establishes isotropic ion transport pathways, thereby markedly enhancing interfacial reaction kinetics and lowering interfacial resistance. As a result, the regeneration graphite exhibits a high specific capacity of 340 mAh/g at 1C and a capacity retention of 90% after 400 cycles. Moreover, regenerated graphite demonstrates a high specific capacity of 243.3 mAh/g at 4C, approximately 1.3 times higher than that of commercial graphite (181 mAh/g), demonstrating superior fast-charging capability. COMSOL simulations further confirm that the reconstructed interface alleviates internal stress and homogenizes the Li + concentration gradient. The proposed strategy demonstrates significant economic advantages over conventional graphite regeneration methods, as evidenced by techno-economic analysis. This work provides a viable pathway for the recycling of spent graphite anodes, thereby contributing to enhanced circularity in the battery industry.