Research on the process of carbon thermal reduction for recovery and resynthesis of LiNi 0.6 Co 0.2 Mn 0.2 O 2

In this paper, a process route for the recovery and resynthesis of spent ternary lithium battery cathode materials was proposed, combined with the recovery process of hydrometallurgy and pyrometallurgy. The results showed that LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) could be completely decomposed into a mixture of Co, Ni, MnO and Li 2 CO 3 by carbothermal reduction roasting process at 650 °C, graphite content of 14% and roasting time of 2 h. The roasted product was subjected to carbonation water leaching at a liquid–solid ratio of 30 ml/g at 20 °C for 60 min to achieve a lithium-leaching rate of 93.33%. For the obtained water-leaching residue, the leaching rate of Mn, Co and Ni could reach 96.63%, 95.57% and 94.22%, respectively, by acid leaching with 3 mol/l H 2 SO 4 at 10 ml/g liquid–solid ratio. Subsequently, the mixed sulfate solution was used to prepare the precursor by co-precipitation method, and then a ternary cathode material could be synthesized by solid-phase sintering with Li 2 CO 3 . The electrochemical test of the resynthesized cathode material was carried out. The initial discharge specific capacity was 175.2 mAh/g, and the capacity retention rate was 91.60% after 100 cycles. The excellent performance shown by the cathode material verifies the feasibility of this recycling method.