Progress and perspectives on recycling spent electrolytes in lithium-ion batteries: A review

Lithium-ion batteries (LIBs) have become indispensable in present-day energy storage applications, containing portable electronics, electric vehicles, and renewable energy systems. However, rapid growth in LIBs usage has caused a parallel surge in end-of-life batteries, presenting environmental and resource recovery challenges. Among the various components, such as cathode, anode, electrolyte, separators, of LIBs, electrolyte has received minimal attention in recycling efforts. Electrolytes, characterized by their flammable, toxic, and volatile nature, pose significant environmental hazards, including the release of harmful gases and pollutants during disposal. This review focuses on the critical need for efficient recovery and reutilization of electrolytes from spent LIBs. Various recovery methods, including solvent extraction, supercritical fluid extraction, pyrolysis, and freezing, are studied for their effectiveness, efficiency, and environmental impact. Additionally, methods for recycling and regenerating recovered electrolytes into high-purity components for direct reuse are explored, addressing economic and sustainability considerations. Finally, major challenges and research gaps have been discussed. Key research gaps include the degradation of electrolytes during battery operation, complex composition of spent electrolytes, and economic feasibility of large-scale recovery technologies.