Separation of lithium and transition metals from leachate of spent lithium-ion batteries by solvent extraction method with Versatic 10

When extracting metals from the leaching liquor of spent lithium-ion batteries (LIBs), the focus of traditional methods has been putting on the separation of transition metals, i.e. manganese, cobalt and nickel, which needs a long treatment process and causes significant loss of lithium. In this study, a simple and efficient process consisting of co-extraction of transition metals with neodecanoic acid (Versatic 10) and recovery of lithium by carbonate precipitation is developed. Firstly, the extraction mechanism of Versatic 10 is explored by slope analysis. And the results show that Versatic 10 has better selectivity to nickel and cobalt than to manganese, and it hardly extracts lithium. Then, practical experiments on solvent extraction conditions are carried out. The total extraction efficiencies of nickel, manganese and cobalt, after two stages of extraction, reach 99.18%, 97.05% and 98.47%, respectively. The experimental results are consistent with the theoretical analysis results. Finally, lithium is recovered by Na2CO3 precipitation. The purity of recovered lithium carbonate is high up to 99.61%. By using this process, the obtained solution of nickel, manganese and cobalt can be directly used to prepare ternary material precursor, and only 8% of lithium is lost.