Highly efficient dissolution of the cathode materials of spent Ni–Co–Mn lithium batteries using deep eutectic solvents

With the development of large-scale energy storage and the electric-vehicle market, the demand for lithium-ion batteries (LIBs) is increasing, resulting in the explosive increase in spent LIBs. The cathode materials of spent LIBs contain multiple transition elements, such as lithium (Li), cobalt (Co), nickel (Ni), and manganese (Mn). The recovery of these metals has significant environmental benefits and high economic value. As a green solvent, deep eutectic solvents (DESs) show great potential in recovering valuable metal elements from spent LIBs. Here, this study proposed a new type of DES formed from betaine hydrochloride and ethylene glycol (betaine hydrochloride and ethylene glycol at a 1 : 5 molar ratio), which can efficiently leach metal elements from spent Ni–Co–Mn lithium batteries (LNCM). The leaching rates of Ni, Co, Mn, and Li can all reach 99% under the conditions of T = 140 °C, t = 10 min and no reductant. Compared with the traditional leaching process, this study provided an economical, green, and efficient approach to recover valuable metals from spent LIBs.