Development and challenges of deep eutectic solvents for cathode recycling of end-of-life lithium-ion batteries

As one of the most important energy storage devices, lithium-ion batteries (LIBs) have experienced a booming development due to the increasing demands of electronics, especially the tremendous growth of electric vehicles. Consequently, a large amount of end-of-life (EOL) LIBs are generated with the massive use of LIBs, bringing the global concerns of environmental pollutions and the waste of critical materials. Thus, the proper handling of EOL LIBs is necessarily required, especially the recycling of electrode materials. This review summarizes the recent development of cathode recycling for EOL LIBs mainly based on the technologies by using deep eutectic solvents (DESs) which are considered as green solvents because of the low cost and biocompatibility. Herein, we establish a clear classification of the current DESs recycling technologies. The merits and weaknesses of traditional DESs leaching and direct DESs repairing technologies are critically assessed. Moreover, their mechanisms are outlined. We provide an available information for EOL LIBs recycling through DESs, and present the corresponding challenges and future perspectives.