The accelerating deployment of lithium-ion batteries (LIB) in electric vehicles (EV) and grid-scale energy storage has intensified pressure on primary resources of Li, Co, Ni, and Mn while generating rapidly increasing streams of end-of-life batteries, thereby necessitating efficient and environmentally responsible recycling strategies. This review critically examines contemporary LIB recycling technologies, spanning industrial pyrometallurgical routes, conventional aqueous hydrometallurgy, direct recycling concepts, and emerging deep eutectic solvent (DES)–based systems for metal leaching and separation. Pyrometallurgical processes remain technologically mature and operationally robust, yet are intrinsically constrained by high energy demand, substantial greenhouse gas emissions, and poor lithium recovery. In contrast, aqueous hydrometallurgical approaches deliver high extraction efficiencies and process flexibility, but depend heavily on strong inorganic acids and reductants, resulting in corrosion issues, complex effluent management, and limited metal selectivity. Within this landscape, DES-based processes have attracted growing attention due to their tunable physicochemical properties, strong metal–ligand interactions, negligible vapor pressure, and potential to couple leaching and separation within a single solvent system. Reported studies demonstrate high recoveries of transition metals and lithium under comparatively mild conditions, with enhanced selectivity in certain hydrophilic and hydrophobic DES formulations. Nevertheless, practical deployment is impeded by high viscosity, sluggish mass-transfer kinetics, uncertainties regarding solvent stability and recyclability, and the paucity of rigorous techno-economic and life-cycle assessments. Overall, DES constitute a scientifically promising platform for next-generation LIB recycling, but their translation beyond laboratory scale will require deeper mechanistic insight, rational solvent design, process intensification, and validation under pilot and industrially relevant conditions. © 2024