Recycling LiNi0.5Co0.2Mn0.3O2 material from spent lithium-ion batteries by oxalate co-precipitation

Abstract

A novel and closed-loop regeneration process for LiNi0.5Co0.2Mn0.3O2 material of spent Li-ion batteries is proposed to achieve valuable metal conservation and natural friendliness. The cathode material was regenerated using mixed acid leaching, oxalate co-precipitation and solid-phase reaction. The optimal conditions for the preparation of precursor are reaction temperature of 50 °C, pH of 1.98, the molar ratio of H2C2O4 to Me2+ of 1.20 and aging time of 24 h. The optimal calcination temperature, calcination time and lithium metal ratio (Li/(Ni + Co + Mn)) are 850 °C, 12 h and 1.05, respectively. Using characterization and analysis of SEM, XRD, TG-DSC and ICP-AES, it was proved that Ni0.5Co0.2Mn0.3C2O4·2H2O precursor, (Ni0.5Co0.2Mn0.3)3O4 intermediate and the regenerative LiNi0.5Co0.2Mn0.3O2 have spherical regularity and uniform particle size under the optimal conditions. The regenerated LiNi0.5Co0.2Mn0.3O2 explicit an initial discharge capacity of 149.528 mAh/g at 0.2 C. At 1 C, the discharge capacity is 135.351 mAh/g, and the capacity retention ratio is 85.45% after 100 cycles. This recycling process does not need complicated metal separation and has the superiorities of briefness operation and low processing costs. The regenerative cathode materials could be applied in next-generation LIBs.