A green, efficient, closed-loop direct regeneration technology for reconstructing of the LiNi0.5Co0.2Mn0.3O2 cathode material from spent lithium-ion batteries

Lithium nickel manganese cobalt oxide in the spent lithium ion batteries (LIBs) contains a lot of lithium, nickel, cobalt and manganese. However, how to effectively recover these valuable metals under the premise of reducing environmental pollution is still a challenge. In this work, a green, efficient, closed-loop direct regeneration technology is proposed to reconstruct LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523) cathode materials from spent LIBs. Firstly, the failure mechanism of NCM523 cathode materials in the spent LIBs is analyzed deeply. It is found that the spent NCM523 material has problems such as the dissolution of lithium and transition metals, surface interface failure and structural transformation, resulting in serious deterioration of electrochemical performance. Then NCM523 material was directly regenerated by supplementing metal ions, granulation, ion doping and heat treatment. Meanwhile, PO₄^3- polyanions were doped into the regenerated NCM material in the recovery process, showing excellent electrochemical performance with discharge capacity of 189.8 mAh g^-1 at 0.1 C. The recovery process proposed in this study puts forward a new strategy for the recovery various lithium nickel cobalt manganese oxide (e.g., LiNi_1/3Co_1/3Mn_1/3O₂, LiNi_0.5Co_0.2Mn_0.3O₂, LiNi_0.6Co_0.2Mn_0.2O₂ and LiNi_0.8Co_0.1Mn_0.1O₂) and accelerates the industrialization of spent lithium ion battery recycling.

Recovery of valuable metals from LiNi0.5Co0.2Mn0.3O2 cathode materials of spent Li-ion batteries using mild mixed acid as leachant

A novel hydrometallurgical process for recycling LiNi_0.5Co_0.2Mn_0.3O₂ cathode materials harvested from spent Li-ion batteries (LIBs) is established in this work. The cathode material LiNi_0.5Co_0.2Mn_0.3O₂ is dissolved in a mixed acid containing phosphoric acid (leaching agent) and citric acid (leaching agent and reductant). Using 0.2 M phosphoric acid and 0.4 M citric acid with a solid to liquid (S/L) ratio of 20 g/L at 90 °C for 30 min, the proposed method results in a leaching efficiency of ca. 100% for Li, 93.38% for Ni, 91.63% for Co, and 92.00% for Mn, respectively. Kinetics of the leaching process is well described by the Avrami equation. It is found that the leaching process is controlled by surface chemical reactions, and the apparent activation energies (kJ/mol) are 45.83 for Li, 83.01 for Ni, 81.38 for Co and 92.35 for Mn, respectively. With aids of various advanced characterizations methods, including UV-Vis, FT-IR and TOC, we find that there are a great deal of citrates and a small amount of dihydrogen phosphates in the mixed acid leachate. This leaching method enjoys advantages of low acid consumption, short leaching time and no need to add extra reductant.