Selective Lithium Recovery via Stepwise Transition Metal Crystallization in a Natural Deep Eutectic Solvent

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Growing electric vehicle adoption necessitates sustainable lithium-ion battery recycling.
• Conventional methods face challenges in lithium selectivity and scalability.
• Deep eutectic solvents (DESs) offer a promising, greener alternative for battery recycling.

Purpose of the Study:

• To develop a highly selective and scalable DES for efficient lithium recovery from spent batteries.
• To address limitations in preferential lithium selectivity and process scalability in current recycling technologies.
• To design a synergistic DES formulation for stepwise separation of lithium and transition metals.

Main Methods:

• A natural DES (1ChCl-10LA-VC) was formulated using choline chloride, lactic acid, and ascorbic acid.
• The DES utilizes synergistic effects for selective lithium solubilization and transition metal precipitation.
• The method was tested on various cathode chemistries and applied to black mass, with scale-up trials.

Main Results:

• Achieved >96% lithium leaching and >94% overall recovery from black mass.
• Demonstrated exceptional selectivity, especially for high-nickel cathodes, and effective removal of impurities.
• The DES showed excellent recyclability over four cycles, with gram-scale reactor tests confirming robustness.

Conclusions:

• The developed DES offers a sustainable, efficient, and scalable solution for lithium-ion battery recycling.
• The stepwise separation mechanism enables high-purity lithium carbonate recovery.
• The process exhibits industrial feasibility and robustness for practical application.