Strategies for overcoming challenges in using deep eutectic solvents for the selective extraction of valuable metals from spent lithium-ion batteries: A review

In the realm of sustainable, portable energy solutions and carbon reduction, lithium-ion batteries (LIBs) have emerged as a mainstay in electronic devices and electric vehicles, thanks to their exceptional performance. However, with the burgeoning production of LIBs, there's a parallel increase in waste batteries, posing significant environmental challenges. Notably, over 25% of LIBs manufacturing costs stem from the cathode active materials, which are rich in valuable metals such as lithium, cobalt, nickel, and manganese. In this context, the imperative for green, efficient recycling technologies is clear, both to enable resource recovery and to mitigate the environmental and health risks posed by hazardous substances. Deep eutectic solvents (DESs) have come to the forefront in this arena, offering promising avenues for the recovery of green metal resources. Known for their potent efficacy in leaching metal oxides, DESs also boast eco-friendly attributes including affordability, recyclability, and biodegradability. This paper delves into the recent advancements in utilizing DES for leaching valuable metals from the cathode materials of spent LIBs. We place special emphasis on innovative methods and perspectives aimed at enhancing leaching efficiency and recovery separation. Furthermore, we address existing challenges in DES-based metal leaching and propose directions for future research and development.