Novel Method for Stepwise Separation of Ni-Co-Mn-Li from Sulfate Leach Solutions of Spent Ternary Lithium-Ion Batteries Using P507/LIX63 Mixture

Sulfate leach solutions of spent ternary lithium-ion batteries (LIBs) contain abundant Mn, Co, Ni, and Li. The selective separation of these elements is an essential treatment for their recovery. Current extraction technology achieves this through a sequential extraction process using multiple extractant systems, resulting in the use of numerous reagents, a long process, and low separation efficiency. The development of a more selective separation method is thus desired. In this paper, we introduce a novel method for the stepwise separation of Ni, Co, Mn, and Li from sulfate leach solutions of spent LIBs through solvent extraction using a single extractant system comprising a 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (P507)/5,8-diethyl-7-hydroxy-6-dodecanonoxime (LIX63) mixture. First, Ni, Co, and Mn are completely co-extracted, leaving Li in the raffinate. Then, Ni, Co, and Mn in the loaded organic solutions are stepwise stripped and separated using 0.05 mol/L, 2.0 mol/L, and 8.0 mol/L H2SO4 solutions, respectively. This novel process is expected to contribute to the hydrometallurgical recovery of spent ternary LIBs.