Efficient closed-loop recovery and regeneration of spent LiCoO2 cathodes using pyruvic acid-based deep eutectic solvents

The recovery of cathode materials from spent lithium-ion batteries (LIBs) is highly beneficial for environmental protection and resource circularity. Here, an efficient closed-loop process is proposed for recycling spent LiCoO 2 . A novel deep eutectic solvent (DES) composed of betaine hydrochloride and pyruvic acid is proposed to achieve rapid and efficient leaching of Li and Co under mild conditions. Leaching kinetics of the DES is analyzed using the shrinking core model, while the leaching mechanism is systematically investigated by integrating experimental and theoretical approaches. Co and Li are recovered from the leachate through precipitation, and the leaching performance of the regenerated DES is also examined. The electrochemical performance of the regenerated LiCoO 2 is tested and compared with commercial LiCoO 2 . Finally, the economic and environmental analysis of the closed-loop recovery process is studied to evaluate its application prospects. This work provides valuable guidance for the comprehensive recycling and utilization of spent LIBs.