Efficient Recovery of Lithium and Iron from Spent Lithium Iron Phosphate Batteries: A Stepwise Process Combining Citric-Acid Leaching and Fenton Technology

The rapid increase in spent lithium iron phosphate (LFP) batteries from electric and hybrid vehicles highlights the urgent need for sustainable and economically viable recycling methods. This study presents an innovative recycling process that efficiently recovers lithium and iron from spent LFP batteries using citric-acid leaching combined with Fenton oxidation (Fe2+/H2O2 system) to generate hydroxyl radicals for enhanced LiFePO4 dissolution. The process includes four steps: citric-acid leaching to release lithium and iron, removal of excess citric acid using lead sulfate (PbSO4), a Fenton reaction to further leach LFP, and lithium recovery through precipitation with sodium phosphate. Response surface methodology was employed to optimize leaching conditions, achieving a lithium recovery rate of 94.74% with a purity of 98.83%. The study demonstrates that the citric-acid concentration, solid–liquid ratio, temperature, and leaching time significantly impact the metal extraction efficiency. The proposed method not only reduces waste and environmental impact but also offers economic benefits. This research provides a sustainable and cost-effective approach for recycling spent LFP batteries, contributing to a circular economy and resource conservation.