Recycling of Waste Cathode Materials for Lithium-Ion Batteries by Deep Eutectic Solvents

The growing demand for recycling of spent lithium-ion batteries (LIBs) drives the need for sustainable methods to recover strategic metals from cathode materials. Deep eutectic solvents (DESs) emerge as green alternatives to conventional acid leaching, offering advantages in selective extraction, reduced chemical usage, and energy efficiency. This review first elucidates the formation mechanisms of DESs and investigates how the parameter optimization of their physicochemical properties (e.g., reducibility, acidity, viscosity) enhances metal recovery rates. Following an in-depth discussion on cathode material leaching processes using DESs, mainstream recovery methods for leaching products and cutting-edge advancements in direct regeneration of cathode active materials are comprehensively summarized. Finally, targeted strategies to address the current challenges in the application of DESs are proposed and an outlook on the future application of DESs in the field of LIB recovery is provided. In summary, this review provides valuable insights into the overall understanding of DESs, aiming to offer references in high-efficiency recycling of LIBs.