Separation and Recovery of Valuable Metals from Ammonia Leaching Solution of Spent Lithium-Ion Batteries

The ammonia leaching system has gained widespread usage in the hydrometallurgical processing of spent lithium-ion batteries (LIBs) due to its exceptional selectivity. In this work, a novel process was developed to recover Li, Ni, Co, and Cu from the NH3·H2O–(NH4)2CO3 leaching solution of spent LIBs. First, solvent extraction using Mextral 54-100 was employed to selectively recover more than 98% of Ni and Cu, with subsequent stepwise stripping of the organic phase using 15 g/L and 60 g/L H2SO4 to prepare NiSO4 and CuSO4 products, respectively. The process realizes the selective separation and recovery of Ni and Cu. Later, the ammonia distillation process was applied to recover Li and Co from the raffinate. Approximately 93% of Co and 64% of Li were precipitated in the form of amorphous Co-bearing carbonate and Li2CO3, respectively. After adjusting the mole ratio of Li and Co in the precipitation to 1, the LiCoO2 cathode material was obtained via two-stage roasting, exhibiting excellent electrochemical performance. The collaborative recovery of Li and Co and the closed-loop circulation of ammonia are realized by ammonia distillation. Moreover, the residual liquid can also return to the ammonia leaching stage, thus avoiding resource waste and the generation of wastewater.