Enhanced Rapid\nand Efficient Recycling of Lithium-Ion\nBattery Cathode by Synergistic Effects of Ternary Deep Eutectic Solvents\nChCl/MCl<sub><i>x</i></sub>/Levulinic Acid

The rapid growth of spent lithium-ion batteries (LIBs)\nraises concerns\nover the supply chain of critical metals and environmental impacts,\nemphasizing the urgent need for efficient recycling technologies.\nDue to their potential to reduce the consumption of energy and avoid\nthe use of corrosive acid, deep eutectic solvents (DESs) have been\nwidely studied to selectively leach and recover valuable metals from\nspent LIBs. There is general agreement that DESs with high acidity,\ncoordination, reducibility, and low viscosity could efficiently dissolve\ncathode materials. However, it is hard to design binary DES compositions\nto fulfill all of these requirements simultaneously. Herein, this\nstudy focuses on the design of ternary DESs, leveraging the synergistic\neffects of their components to achieve strong coordination and low\nviscosity, enhanced acidity, and reducibility to efficiently extract\nvaluable metals. Specifically, ChCl/CuCl:4Levulinic acid demonstrated\nexceptional leaching capabilities, recovering over 90% of LiCoO<sub>2</sub> within 10 min. Furthermore, to ensure the purity of recovered\nmetal products, ChCl/LiCl:8Levulinic acid was investigated to realize\nthe efficient leaching, recovery, and DES regeneration process. It\nwas verified that ChCl/LiCl/8Levulinic acid has high leaching efficiency\nand good cycling stability and facilitates a convenient recycling\nprocess. Overall, this work demonstrates the potential of tailored\nternary DESs for the efficient leaching of cathode materials and proposes\na sustainable process to realize metal recovery from spent LIB cathode\nand DES regeneration.