Efficient Recovery of Lithium and Cobalt from Spent Lithium-Ion Batteries Using a ChCl-OA-H2O Deep Eutectic Solvent
The proliferation of lithium-ion batteries (LIBs) in portable electronics and electric vehicles has generated a pressing need for sustainable recycling of spent batteries. Conventional pyrometallurgical and hydrometallurgical routes suffer from low metal recovery efficiencies or require additional precipitants. This study introduces a clean and efficient process for recovering lithium (Li) and cobalt (Co) from spent LiCoO2 cathode materials using a choline chloride-oxalic acid-water (ChCl-OA-H2O) deep eutectic solvent (DES). The method exploits selective precipitation of Co as cobalt oxalate dihydrate (CoC2O4·2H2O) followed by water-content-regulated recovery of Li as lithium oxalate (Li2C2O4) via evaporation crystallization, eliminating the need for external precipitants. Under optimized conditions (molar ratio 1:1:8, solid-liquid ratio 100 g/L, 90 °C, 6.5 h), the leaching efficiency of Li reached 99.4%, with recovery efficiencies of 88.3% for Li and 97.8% for Co. The DES system demonstrated robust cycling stability, maintaining Li and Co recoveries of 78.1% and 92.8% after six regeneration cycles. This work provides a low-pollution, economically viable pathway for LIB recycling, contributing to resource sustainability and offering significant industrial potential.