A sodium persulfate-assisted roasting–leaching strategy for recovering spent LiFePO4 batteries

Abstract

Lithium iron phosphate (LFP) batteries have been widely adopted in the electric vehicle sector owing to their high safety and excellent cycling stability. With the continuous expansion of the global electric vehicle fleet, the generation of spent LFP batteries is rapidly increasing, while the pressure on lithium resource supply is becoming increasingly significant. To address this dual challenge, this study proposes a selective lithium extraction process based on sodium persulphate-assisted roasting. During the sulphation roasting process, lithium is preferentially converted into soluble salts, thereby significantly enhancing lithium recovery efficiency. In addition, the reaction mechanisms and phase transformation behaviours during roasting are systematically investigated. Under optimised process conditions, the lithium leaching rate exceeds 98.67% after water leaching. Meanwhile, iron and phosphorus are predominantly retained in the slag phase as stable compounds, providing a solid basis for the subsequent high-value utilisation of these elements. Compared with other sulphation roasting systems, the proposed method not only enables highly selective lithium extraction but also significantly reduces gas emissions during roasting, demonstrating improved environmental compatibility. Therefore, this process integrates high efficiency, environmental sustainability, and potential economic feasibility, offering a promising technological route for the resource recovery of spent LFP batteries with strong industrial application prospects.