The multi-component utilization of spent lithium-ion batteries for closed-loop recycling of valuable metals: Spent graphite-promoted separator pyrolysis for cathode reduction

Current lithium-ion batteries (LIBs) recycling research mainly focuses on valuable metals in cathodes, while the combined application of separators (polyethylene, PE) and spent graphite (SG) is extremely rare. To achieve comprehensive utilization of various battery components, this study proposed the co-pyrolysis of SG and PE for cathode recycling. In addition, the dynamic change laws of gases during the reduction process were further explored. The results found that under promoting of SG (blending ratio: 40%), the yield of reducing gases produced by PE pyrolysis increased by 35.9%, mainly consisting of H 2 (19.7 vol%) and CH 4 (40.9 vol.). Notably, H 2 and CH 4 preferentially participated in cathode reduction, while the reaction rate of C 2 H 4 accelerated after 10 min. The optimal temperature (550 ℃), reaction time (30 min) and PE reductant proportion (20%) were determined through vacuum ex-situ reactions. The Li leaching efficiency higher than 96.4% was attained after water leaching of reduction products. The recovered Li 2 CO 3 and NiCoMnO x residue were successfully regenerated into Re-NCM, delivering a capacity of 152.2 mAh/g at 1 C and a high retention rate of 93.2% after 100 cycles. Furthermore, EverBatt model analysis confirmed the significant environmental and economic benefits of this process, demonstrating a sustainable and cost-effective strategy for spent LIBs recycling.