A Sustainable Direct Recycling Method for LMO/NMC Cathode Mixture from Retired Lithium-Ion Batteries in EV

Abstract

Direct recycling methods offer a non-destructive way to regenerate degraded cathode material. The materials to be recycled in the industry typically constitute a mixture of various cathode materials extracted from a wide variety of retired lithium-ion batteries. Bridging the gap, a direct recycling method using a low-temperature sintering process is reported. The degraded cathode mixture of LMO (LiMn₂O₄) and NMC (LiNiCoMnO₂) extracted from retired LIBs was successfully regenerated by the proposed method with a low sintering temperature of 300°C for 4 h. Advanced characterization tools were utilized to validate the full recovery of the crystal structure in the degraded cathode mixture. After regeneration, LMO/NMC cathode mixture shows an initial capacity of 144.0 mAh g⁻¹ and a capacity retention of 95.1% at 0.5 C for 250 cycles. The regenerated cathode mixture also shows a capacity of 83 mAh g⁻¹ at 2 C, which is slightly higher compared to the pristine material. As a result of the direct recycling process, the electrochemical performance of degraded cathode mixture is recovered to the same level as the pristine material. Life-cycle assessment results emphasized a 90.4% reduction in energy consumption and a 51% reduction in PM2.5 emissions for lithium-ion battery packs using a direct recycled cathode mixture compared to the pristine material.