Effective recycling of critical metals from LiCoO2 batteries by hydrated deep eutectic solvents: Performance, kinetic and mechanism

The global challenges of environmental contamination caused by discarded lithium-ion batteries (LIBs) and the loss of key metals have become prominent. Presently, deep eutectic solvents (DESs) have shown significant potential in resolving problems related to the disposal of spent LIBs. In this study, we employ low viscosity hydrated DES to selectively extract critical metals from LiCoO2 (LCO). The solubility of the choline chloride/citric acid DES system can be significantly enhanced by controlling the quantity of water. Concurrently, the viscosity of hydrated DESs decreased to 69.1 cP when the water content was increased to 25.7 wt%. Under optimal conditions, 97.6 % of cobalt (Co) and 100 % of lithium (Li) were extracted by leaching from LCO using hydrated DESs. Hydrated DESs are also efficient for the recycling of NCM523 batteries. Meanwhile, a thorough analysis was conducted on the process of extracting metal in hydrated DESs system. In addition, the precipitation efficiency of Co can be increased to 99.69 % by altering the speciation of the leached metal. The proposed approach for recovery is both economical and uncomplicated, allowing for the reuse of the recovered DESs to efficiently mitigate resource depletion.