Comprehensive and high-efficiency leaching process for achieving full-component recovery of spent lithium iron...

The sustainable recycling of spent LiFePO₄ (S-LFP) batteries is crucial for resource security and environmental protection. However, current recycling methods are largely constrained by poor economic returns and incomplete component recovery. Here we report an integrated, closed-loop strategy that achieves full-component recovery of S-LFP cathodes through synergistic HCl-H₂O₂ leaching followed by Na₂CO₃-assisted roasting-water leaching. Systematically optimized via single-factor and response surface experiments, the leaching step selectively extracts 98.32% of Li while limiting Fe and P co-leaching to less than 1.3%, enabling the direct recovery of high-purity battery-grade Li₂CO₃. The residual lithium extraction residue (LES) is subsequently valorized: Na₂CO₃-assisted roasting converts FePO₄ into soluble Na₃PO₄ and insoluble Fe₂O₃, achieving a P leaching efficiency of 98.75% while Fe leaching is suppressed to only 0.78%. Thermodynamic analysis and detailed characterization (XRD, XPS, SEM-EDS, FT-IR) confirm the reaction mechanisms and feasibility. Economic evaluation shows that the integrated process yields a net profit of $1.649 per kilogram of S-LFP treated, which is $0.145 higher than that of conventional routes. This work provides a technically robust, economically attractive, and environmentally benign strategy for the value-added recovery of S-LFP batteries, presenting strong potential for industrial implementation and contributing to a circular battery economy.