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Spent Li-ion battery (LIB) recovery has become the hot research area due to its surge in quantity and release of heavy metals and toxic substances harmful to the environment. Green and efficient recovery methods are of great significance for the recovery of valuable metals. Herein, an oxalic acid-based deep eutectic solvent (DES) with the weak acidic character and reducibility of oxalic acid was designed for the recovery of valuable metals from spent LIBs via a sustainable and convenient process. Nearly 96.1% of Li and 96.3% of Co can be extracted from lithium cobalt oxide at 120 °C. The DES can extract valuable metals from cathode materials and separate metal ions by itself after extraction without destroying its own structure in a one-pot extraction process. The composition and the structure of DES have been maximum retained and could be intact recycled for another recovery process. After five cycles, the Li and Co extraction efficiencies were maintained above 92.9 and 74.5%, respectively. This work provides a sustainable one-pot recovery process with inexpensive and simple operations for valuable metal recovery from spent LIBs.
Lu et al. (Thu,) studied this question.