Synergistic electrochemical multi-resources recovery from spent LiFePO₄ and etching solvents

The recycling of spent lithium (Li)-ion batteries (LFP) is crucial for resource sustainability and environmental protection. Conventional hydrometallurgical processes often require the addition of external strong oxidizing agents and elevated temperatures to achieve satisfactory metal leaching, presenting both economic and environmental challenges. This study proposes an innovative and sustainable "waste-to-wealth" strategy for the simultaneous recovery of valuable metals from spent LFP cathodes and copper (Cu) from etching waste liquid. The core of this strategy is an integrated "three-birds-with-one-stone" separation technology combining electrochemical oxidation and deposition. Without requiring external oxidants, chloride ions naturally present in the etching wastewater are electrochemically oxidized in situ at a Ru-Ir-Ti anode to generate active chlorine species, which effectively destroy the LFP crystal structure for Li extraction. Simultaneously, Cu ions are directly electrodeposited onto the cathode as metallic Cu powder. Under optimal conditions (0.2 M HCl, 120 min), leaching efficiencies of 100 % for Li and 73.3 % for Fe were achieved, along with a Cu deposition efficiency of 99.6 %. Subsequent selective precipitation yielded high-purity, battery-grade Li₃PO₄ (99.5 % purity). Mechanistic studies confirmed that active chlorine species are the primary contributors to the highly efficient Li leaching. This novel process eliminates the need for external oxidants and heating, offering a greener, more cost-effective, and streamlined alternative for the coordinated recovery of spent batteries and heavy-metal-containing wastewater, demonstrating significant potential for practical application within a circular economy framework.