<p>Deep eutectic solvents (DESs) are gaining attention as an ecofriendly alternative leaching agent for recycling spent lithium-ion batteries (LIBs) owing to their cost-effectiveness and environmental advantages. This study developed a new DES composed of choline chloride (ChCl), chloroacetic acid (CAA), and ethylene glycol (EG) to increase the flowability and enhance the leaching efficiency of metals from spent LIBs. Under optimal conditions—defined by a ChCl:CAA:EG molar ratio of 1:1:2, a temperature of 110 °C, a solid–liquid ratio of 15 g/L, and a reaction duration of 3 h—the DES achieved leaching efficiencies of 90% for lithium and 100% for nickel, cobalt, and manganese. Subsequently, through stepwise solvent extraction with D2EHPA and oxalic acid, the metals were recovered separately. Fourier transform infrared spectroscopy analysis showed that the bond structure of ChCl–CAA–EG DES was intact after the metal recovery with solvent extraction and that the functional groups of the DES remained, allowing them to be reused. The stepwise reuse experiments revealed that the ChCl–CAA–EG DES could be reused in the second cycle, after which the efficiency decreased by approximately 20%. These results suggest that the leaching with the ChCl–CAA–EG DES and subsequent solvent extraction procedure is an efficient and sustainable alternative to enhance the recovery of valuable metals from spent LIBs.</p> Graphical Abstract <p></p>