Sustainable lithium-ion cathode recycling enabled by natural deep eutectic solvents

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This work presents a sustainable hydrometallurgical process for recovering lithium (Li), cobalt (Co), nickel (Ni), manganese (Mn), and aluminum (Al) from spent NMC 622 lithium-ion batteries using natural deep eutectic solvents (NADES). After a mild pretreatment that efficiently removes the aluminum foil, six NADES formulations were evaluated, with the ternary mixture of choline chloride, lactic acid, and ascorbic acid (ChCl–LA–AA) showing the highest and most consistent metal extraction efficiencies. Optimal conditions (60% water content, 20 g L −1 solid–liquid ratio, 80 °C) enabled rapid leaching, achieving near-quantitative recoveries within 10 min. Transition metals were precipitated as a crystalline, mixed Ni–Mn–Co oxalate precursor suitable for cathode resynthesis, while Li was purified as Li 3 PO 4 with a characteristic flake-assembled morphology. The process achieved a Li recovery yield of 66% and a product purity of 94%. Overall, the recovery efficiencies meet the European Batteries Regulation targets for lithium-based batteries for 2027 and 2031, demonstrating that NADES-based leaching offers a fast, green, and scalable route for circular LIB materials recovery.