Efficient and Prioritized Lithium Recovery from Spent Li(Ni0.5Co0.2Mn0.3)O2 Cathodes via SO2 Treatment

With the wide application of ternary lithium-ion batteries, the increased usage of batteries has resulted in a corresponding rise in the amount of discarded batteries. Here, we propose an efficient and prioritized lithium extraction process with a low environmental impact for the recovery of valuable metal components from spent LiNi0.5Co0.2Mn0.3O2 cathode materials. SO2 calcination–water leaching was used to recover Li, while H2SO4 acid leaching facilitated the recovery of Ni, Co, and Mn, yielding a precursor solution for the treatment of discarded NCM batteries. The effects of calcination temperature, calcination time, water leaching time, water leaching liquid–solid ratio, different battery ratios, acid leaching time, acid leaching liquid–solid ratio, and acid leaching temperature were optimized. The acid leaching process was controlled by surface chemical reactions through kinetic analysis. Under optimal conditions, Li was converted to soluble Li2SO4, achieving an impressive leaching rate of 99.7%. Ni, CO, and Mn were converted to their respective oxides. Furthermore, it was demonstrated that the formation of Li2Mn(SO4)2 from Mn with Li during calcination enhances the leaching efficiency across different battery composition ratios. The activation energies of Ni, Co, and Mn during the acid leaching process were determined by kinetic calculations, yielding values of 130.19, 133.05, and 134.09 kJ mol–1, respectively. This study provides a novel method for recycling spent NCM cathode materials.