Enhanced Rapid and Efficient Recycling of Lithium-Ion Battery Cathode by Synergistic Effects of Ternary Deep Eutectic Solvents ChCl/MCl_<i>x</i>/Levulinic Acid

The rapid growth of spent lithium-ion batteries (LIBs) raises concerns over the supply chain of critical metals and environmental impacts, emphasizing the urgent need for efficient recycling technologies. Due to their potential to reduce the consumption of energy and avoid the use of corrosive acid, deep eutectic solvents (DESs) have been widely studied to selectively leach and recover valuable metals from spent LIBs. There is general agreement that DESs with high acidity, coordination, reducibility, and low viscosity could efficiently dissolve cathode materials. However, it is hard to design binary DES compositions to fulfill all of these requirements simultaneously. Herein, this study focuses on the design of ternary DESs, leveraging the synergistic effects of their components to achieve strong coordination and low viscosity, enhanced acidity, and reducibility to efficiently extract valuable metals. Specifically, ChCl/CuCl:4Levulinic acid demonstrated exceptional leaching capabilities, recovering over 90% of LiCoO2 within 10 min. Furthermore, to ensure the purity of recovered metal products, ChCl/LiCl:8Levulinic acid was investigated to realize the efficient leaching, recovery, and DES regeneration process. It was verified that ChCl/LiCl/8Levulinic acid has high leaching efficiency and good cycling stability and facilitates a convenient recycling process. Overall, this work demonstrates the potential of tailored ternary DESs for the efficient leaching of cathode materials and proposes a sustainable process to realize metal recovery from spent LIB cathode and DES regeneration.