High-efficiency leaching of valuable metals from waste Li-ion batteries using deep eutectic solvents.

With the penetration of lithium-ion batteries (LIBs) into electric vehicles, the recycling of waste LIBs is inevitable from the perspective of health, economy and environmental protection. Herein is reported a novel green method for extracting valuable metals from the cathode of LIBs, in which the Deep Eutectic Solvent (DES) is used as leachate to dissolve electrode material waste. Mixing choline chloride (ChCl) and malonic acid is helpful to effectively improve the reduction ability of DES, resulting in superior leaching efficiency. At the lower temperature (100 °C), the leaching efficiency of cobalt and lithium reached up to 98.61% and 98.78%, respectively. X-ray absorption near edge structure (XANES) spectroscopy demonstrated that DESs could act as both leachate and reducing agent, which could destroy the covalent bonds of metal oxides to form a cobalt (II)-chlorine complex. This method is straightforward to operate and does not involve the additional reducing agents, which is held promise to bring economic and sustainable development prospects in the field of lithium battery development.