Oxygen-driven selective lithium recovery from spent LiFePO4 batteries using malic acid

Due to the intrinsically low added value of the recovered materials, recycling spent lithium iron phosphate (LFP) cathodes is not always economically attractive. However, because battery components can contaminate soil and groundwater if improperly handled, they pose a threat to the ecosystem and must be recycled in a way that is both environmentally and economically feasible. This study presents an environmentally friendly process for the selective recovery of lithium, iron and phosphorous based on the combined action of malic acid and atmospheric oxygen. Under optimized conditions, more than 99% of lithium is dissolved, while iron and phosphorous leaching remain below 10%, ensuring both high efficiency and selectivity. Iron and phosphorous are recovered as phase-pure iron phosphate, which may be used as a precursor in the synthesis of fresh LFP cathodes. Thermodynamic and kinetic analyses, supported by multiple analytical techniques, were employed to provide insightful, mechanism-based discussions of element recovery and to elucidate the roles of malic acid and atmospheric oxygen. Owing to its reliance on low-cost, benign reagents, this method offers a sustainable and economically viable route for LFP recycling, mitigating the environmental burden of conventional hydrometallurgical processes and advancing the circular economy of lithium-ion batteries.