Room-Temperature Hydrometallurgical Recovery of Lithium and Iron from Spent LiFePO4 Batteries via Selective Leaching and Oxalic Acid Precipitation

The increasing demand for lithium-ion batteries (LIBs) highlights the need for efficient recycling strategies to recover critical materials and reduce environmental impact. This study presents an optimized hydrometallurgical process for the recovery of lithium (Li) and iron (Fe) from spent lithium iron phosphate (LiFePO4 or LFP) battery cathodes through selective leaching and precipitation. A factorial experimental design was employed to model the leaching process and to optimize the leaching parameters and the best efficiency was achieved at Acid Conc. (1.5 N), Agitation (350 rpm), and solid-to-liquid ratio (15%) and achieved Li (80%), Al (0.28%), and Fe (76%) recovery. The intensified conditions (H2SO4 3 N, 350 rpm, 20% solid-to-liquid ratio) outside the factorial domain for potential interest in scale-up were also applied to achieve 90.8% Li and 98.0% Fe co-extraction at room temperature within only 30 min, in contrast to the elevated temperatures (60–95 °C) typically required in the literature. To enhance Fe–Li separation, various precipitation agents were tested; among these, oxalic acid at the stoichiometric dosage achieved 98.1% Fe removal while limiting Li loss to 2%, making it the most effective purification method. By combining mild, room-temperature leaching with highly selective Fe removal, this approach reduces the energy and reagent requirements associated with conventional thermally assisted LFP recycling routes. Overall, this work provides an effective approach for recovering valuable components from spent LIBs, reducing material losses and contributing to the development of circular resource recovery strategies.