High-efficiency leaching of valuable metals from waste lithium-ion ternary batteries under mild conditions using green deep eutectic solvents†

Recently, the production and demand for lithium-ion batteries (LIBs) have increased owing to the increasing number of electric vehicles and electronic products. This surge has considerably increased the volume of spent LIBs, leading to environmental damage and economic losses. Thus, the recycling of spent LIBs is critical because it enables the recovery of valuable metals and mitigates environmental impacts. This work introduces a novel environmentally friendly and biodegradable deep eutectic solvent (DES) for leaching valuable metals from waste LIBs, which includes ascorbic acid (VC) derived from fruits and dimethyl-beta-propiothetin chloride (DMSP) derived from fish attractants. It is noteworthy that the utilization of chemical reagents in this study was significantly diminished, with VC and DMSP accounting for 16.5% and 8.5% of the total solvents, respectively—which decreased recycling costs and alleviated the environmental burden. The leaching of LiNi_1/3Co_1/3Mn_1/3O₂ (LNCM111) cathode materials was rapidly achieved at a low temperature of 50 °C within 14 minutes. The coordinated action of Cl⁻ ions and the reducing effect of VC in DMSP resulted in a 99% leaching efficiency for Lithium, Cobalt, Manganese, and Nickel. In addition, the leaching mechanism was comprehensively investigated via kinetics and density functional theory calculations. This efficient, easy-to-operate, low-cost, and sustainable leaching process involving the DES demonstrates considerable potential for recycling LIBs, offering an environmentally friendly and effective solution for LIB reuse.