Innovative Application of Acid Leaching to Regenerate Li(Ni_1/3Co_1/3Mn_1/3)O₂ Cathodes from Spent Lithium-Ion Batteries

Rapid development of energy storage system causes a burst demand of lithium-ion batteries (LIBs), and large number of spent LIBs with high valuable metals are produced. Here we propose a novel application of oxalic acid leaching to regenerate Li(Ni_1/3Co_1/3Mn_1/3)O₂ (NCM) cathodes from spent LIBs. With lithium dissolving into the solution, the transition metals transform into oxalate precipitates and deposit on the surface of spent NCM cathodes, separating lithium and transition metals in one simple step. After mixing with certain amount of Li₂CO₃, the oxalate precipitates together with unreacted NCM are directly calcined into new NCM cathodes. The regenerated NCM after 10 min leaching exhibits the best electrochemical performances, delivering the highest initial specific discharge capacity of 168 mA h g^-1 at 0.2C and 153.7 mA h g^-1 after 150 cycles with a high capacity retention of 91.5%. The excellent electrochemical performances are attributed to the submicrometer particles and voids after calcination, as well as the optimal proportion of elements. This process can make the most of valuable metals in the spent cathodes, with >98.5% Ni, Co, and Mn recycled. It is simple and effective, and provides a novel perspective of recycling cathodes from spent LIBs.