Catalytic low-temperature N-doped carbon modification of spent graphite enabling Li3N-rich SEI for high-stability lithium-ion anodes

Regenerating graphite anode materials from spent lithium-ion batteries (LIBs) is essential for improving resource utilization and reducing environmental impact. However, conventional recycling routes often require excessive energy input, incur high costs, and deliver regenerated graphite with unsatisfactory electrochemical performance. To address these limitations, we propose a low-temperature catalytic repair strategy based on an integrated carbon source, nitrogen source, and catalyst system. Chitosan serves as both the carbon precursor and the in situ nitrogen dopant, while a cobalt salt functions as both a catalyst and a pore-forming template. At a mild temperature of 600 °C, a porous nitrogen-doped graphene-like carbon (PNGC) layer is constructed on the surface of spent graphite (SG). This functional layer repairs surface defects and promotes the formation of a Li 3 N-rich solid electrolyte interphase (SEI) during cycling. Benefiting from this interfacial engineering, Li + transport kinetics are markedly accelerated, parasitic electrolyte decomposition is suppressed, and both the rate capability and cycling stability of the graphite anode are significantly improved. The regenerated graphite anode delivers an initial Coulombic efficiency of 86.73% and reversible capacities of 370.6, 336.1, and 206.9 mAh g −1 at 0.1C, 1C, and 2 C, respectively, with 90.13% capacity retention after 700 cycles at 1 C, demonstrating performance comparable to that of commercial graphite. Life cycle assessment (LCA) further confirms the environmental and economic advantages of this low-temperature catalytic process, offering a green and feasible pathway for the closed-loop high-value utilization of spent graphite. The constructed porous nitrogen-doped graphene-like carbon (PNGC) layer repairs surface defects of spent graphite, induces the formation of a Li 3 N-rich stable SEI, and provides fast Li + transport channels, synergistically enhancing the electrochemical performance of regenerated graphite. Download: Download high-res image (337KB) Download: Download full-size image