Lithium recovery via redox bipolar membrane electrodialysis for the acid-free recycling of spent Lithium Iron Phosphate battery cathodes

With the rising demand for batteries with iron phosphate (LiFePO4, LFP) cathodes in electric vehicles, developing sustainable and cost-effective recycling processes is becoming increasingly important. Acid-free leaching with Fe3+ ions provides an environmentally friendly approach to lithium recovery; however, selectively separating Li+ over Fe2+ which is the predominant species in the leachate formed through isomorphous substitution, remains challenging because of their comparable physicochemical and electrochemical characteristics. This study develops a redox-mediated bipolar membrane electrodialysis (Redox-BMED) system for efficiently recovering lithium recovery from acid-free leachates while simultaneously producing of lithium hydroxide (LiOH). Unlike conventional electrodialysis, which relies on water splitting, Redox-BMED utilizes redox reactions to enhance separation performance. The system is evaluated under various conditions, comparing two different membranes (nanofiltration and ion-exchange membranes) and examining the ion selectivity and its stability during long-term operation for 24 h. The Redox-BMED system recovered lithium and successfully produced LiOH (> pH 12) from real leachates obtained from the acid-free leaching of spent LFP batteries. These results highlight Redox-BMED as a promising, environmentally benign electrified platform for lithium recovery in next-generation battery recycling.