Selective extraction of lithium from acidic chloride leachates of spent batteries

Solvent extraction of lithium (Li) from acidic leachates of spent batteries black mass (BM) over nickel (Ni), manganese (Mn), and cobalt (Co) can allow easy integration of Li recycling into conventional hydrometallurgical flowsheets, eliminating the need for thermal pretreatment of BM. In this study, a ternary organic phase consisting of iron (Fe3+), tributyl phosphate (TBP), and 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester (P507) to selectively extract Li+ over Ni2+, Mn2+, and Co2+ has been developed. The extraction, scrubbing, stripping, and regeneration conditions were optimized, and McCabe–Thiele diagrams were constructed. An increasing P507/Fe (optimum 1.5–1.7) mole ratio was found to enhance Li release during water stripping but suppressed extraction. FTIR spectroscopy confirmed the stability of Fe3+ in the organic phase during water stripping. The Fe3+ preloaded solvent gave > 90% Li (7.7 g/L initially) extraction at an organic/aqueous phase ratio of 7 in four stages. After six cycles, the Li extraction efficiency was maintained, showing excellent selectivity, reducing NMC metal ions from 7.6–64 g/L to only 0–0.05 g/L in purified strip solution. The developed solvent system facilitates water stripping, eliminating the need for acids and alkalis, and allows easy integration in established chloride-based battery recycling processes, enabling early Li recovery from the leachate.