Simultaneous separation and leaching of cathode materials from spent lithium-ion battery using ternary deep eutectic solvents

The efficient and sustainable metal recovery from spent Li-ion battery (LIBs) cathode materials is crucial for environmental protection and resource security. During the hydrometallurgical recovery process, the cathode materials must be separated from the current collector (Al foil) before leaching the metals. However, current separation and leaching processes are conducted separately, resulting in cumbersome process flows and significant reagent consumption. To address these issues, a ternary deep eutectic solvent (DES) composed of choline chloride, malonic acid and 2-pyrrolidone was used in this study for the simultaneous separation and leaching of LiCoO2 cathode material. The DES achieved a separation efficiency of over 98 wt% for the cathode materials, with leaching efficiencies exceeding 96 % for Li and Co and less than 4 % for Al. The cathode material was separated from the Al foil through disruption of the molecular chains of the PVDF binder. During the leaching process, Co3+ in LiCoO2 was reduced to Co2+ by malonic acid and existed in the form of [CoCl4]2-. The Li and Co in the leachate were recovered as carbonate and oxalate precipitates, respectively, allowing for the reuse of the DES after metal recovery. Solvent reusability tests indicated that the DES maintained an excellent performance after multiple cycles. This study provides a novel and environment-friendly strategy for the efficient recycling of metals from spent lithium-ion batteries.