Simultaneous multi-element recovery from spent LiFePO₄ batteries by diethyl tartrate-assisted hydrothermal leaching

Sustainable recycling of spent LiFePO₄ (LFP) batteries is essential for protecting both resources and environment. Conventional hydrometallurgical methods focus primarily on Li recovery, yet they depend on corrosive acids and external oxidants while generating phosphorus-rich iron residues-posing significant economic and environmental challenges. To address these issues, we propose an innovative diethyl tartrate-based hydrothermal treatment method that facilitates acid- and oxidant-free recycling of spent LFP cathode materials. By carefully controlling the leaching conditions, selective release exceeds 98% for Li and P, whereas Fe leaching remains negligible at 0.3%. Mechanistic studies confirmed that the high-efficiency leaching of Li and P is attributed to the combined effect of acetic acid and tartaric acid produced by the hydrothermal reaction of diethyl tartarate. Moreover, the high-quality Li₃PO₄ was prepared from leaching filtrate via purification-precipitation, and the purity of 99.08% FeC₄H₄O₆ was obtained from leaching residue via redissolving-precipitation. This work establishes a sustainable, efficient pathway to fully recover valuable resources from spent LFP batteries.