Selective separation and recovery of lithium, nickel, MnO2, and Co2O3 from LiNi0.5Mn0.3Co0.2O2 in spent battery

The recovery of valuable metals from the LiNi 0·5 Mn 0·3 Co 0·2 O 2 in spent batteries deserves more attention. We report a series of feasible procedures to selectively recover the four metals (Li, Ni, Mn, and Co) using a combination of hydrometallurgical and pyrometallurgyical processes. Firstly, oxalic acid is used to dissolve Li and precipitate the other three metals in oxalate forms. It is found that under the optimal condition, about 98% of the Li is dissolved, and on average 93% of the other three metals are transformed to precipitated oxalates. The oxalates are then transformed to NiO·Mn 2 O 3 ·Co 3 O 4 by being calcinated at 723 K under atmospheric environment. The selective recovery of NiO·Mn 2 O 3 ·Co 3 O 4 can be achieved by using H 2 SO 4 under three different conditions. The first step is to use H 2 SO 4 to selectively dissolve CoO from the Co 3 O 4 . Then the combination of H 2 SO 4 and ultrasound is adopted to dissolve NiO, during which the ultrasound destroys the surficial oxide film on the NiO. Afterwards, the Mn 2 O 3 is transformed to MnO 2 and Mn 2+ in heated H 2 SO 4 . The Co, Ni and Mn ions are dissolved in a sequence, which facilitates their separation and recovery. As the main components of the final residual solids, Co 2 O 3 and MnO 2 present in distinctly different sizes and shapes, which are beneficial for their separation and direct usage. • Four metals in LiNi 0·5 Mn 0·3 Co 0·2 O 2 are selectively recovered. • A hydrometallurgical and pyrometallurgyical combined process is developed. • Oxalic acid dissolves Li and precipitates other three metals in oxalate forms. • The precipitated oxalates are transformed to NiO·Mn 2 O 3 ·Co 3 O 4 for treatment. • NiO·Mn 2 O 3 ·Co 3 O 4 is selectively recovered by H 2 SO 4 under different conditions.