Separation of Lithium and Transition Metals in Leaching Solution of Used Lithium Ion Battery with Sec-octylphenoxyacetic Acid

The recovery of critical metals from spent lithium-ion batteries (LIBs) is important to sustainable development and environment protection. In this paper, sec-octylphenoxyacetic acid (CA-12) was first used to recover valuable metals in LIBs. The effects of phase modifier, initial feed pH, extraction kinetics and thermodynamics, CA-12 concentration and saponification degree were studied and optimized. Under the optimal conditions, 99 % of nickel, cobalt and manganese were co-extracted to the organic phase, and the loss of lithium was 7 %. The extracted metal ions could be stripped with 0.04 mol/L HCl equivalently. In the spent LIBs powder leaching experiment, leaching efficiencies of all components were greater than 95 %. In the impurity removal stage, extractant N902 was used to remove copper, while iron and aluminum were eliminated by hydrolysis. After two-stage extraction, the total extraction efficiencies of nickel, cobalt and manganese reached 99.7 %, 99.4 %, 98.45 %, respectively. Finally, lithium in the raffinate was precipitated by saturated Na2CO3, the purity of recovered Li2CO3 was up to 97.7 %. After 5 times cycles, CA-12 still maintained excellent extraction capacity, showing its potential application prospects for recovering critical metals form spent LIBs.