A Green Approach for Selective Ionometallurgical Separation of Lithium from Spent Li-Ion Batteries by Deep Eutectic Solvent (DES): Process Optimization and Kinetics Modeling

Failure to recycle valuable metals from lithium-ion batteries (LIBs) could directly lead to various environmental issues, such as ecological toxicity with inevitable impacts on environment and society health. This study presents a green process for selective recovery of Li from spent LIBs based on a ternary deep eutectic solvent. The effects of solid-to-liquid ratio, temperature, and variations of deep eutectic solvent (DES) component concentrations on the selectivity of the leaching process were studied. A ternary DES based on choline chloride, urea and ethylene glycol was found to be more selective than conventional binary DESs and made it possible to extract the Li in the lower temperatures (75–100°C). In such temperatures, DESs present better viscosity and higher stability. In the optimum conditions, 92.83%, 1.61%, 0.72%, and 0.42% recoveries were obtained for Li, Co, Ni, and Mn, respectively. Kinetic modeling indicates that mixed control models were best fitted to all data. Moreover, the results indicated that the activation energy for Li extraction is 21.15 KJ/mol. Pearson correlation assessment relieved that L/S was the most effective factor with a positive impact (r > +0.5) on Li recovery among all variables. Furthermore, temperature impacts the selectivity of the leaching process. The illustrated selectivity coupled with biodegradability and the possibility of re-utilization of the DESs opens a novel way for the greener recovery of values from wastes.