Abstract
The rapid growth of lithium-ion battery usage in electric vehicles and energy storage systems has intensified the need for efficient recycling technologies to recover critical metals from black mass. Traditional hydrometallurgical methods often rely on harsh chemicals, raising environmental and economic concerns. Deep eutectic solvents (DESs) are receiving great attention for metal recovery because of their high selectivity, environmentally friendly character, low melting point, good stability, and low corrosive properties. In this study, an organic acid based eutectic solvent was developed and applied for selective lithium leaching from various black mass compositions (NMC, LFP and a mixed composition, LLC) under mild conditions. The process demonstrated good extraction kinetics with high lithium recovery from 70-90% across different chemistries in 3-9 hours, followed by solvent regeneration achieved through a simple distillation step. An analysis of the distillation residue from all the tests confirmed lithium-containing phases, indicating potential for downstream conversion. Further, the concentration of other battery metals, in all cases, varied from less than 1 to 5%, with an exception of nearly 15% manganese at 3 hours in the LFP leach solution. This approach underscores the promise of eutectic solvents as sustainable alternatives for battery recycling. Future work will focus on optimizing process parameters, scaling up, and integrating the method into circular economy frameworks for critical metal recovery.