Upcycling spent LiFePO4 via a fluorine doping-assisted direct regeneration strategy for high-rate lithium-ion batteries
The escalating retirement of lithium-ion batteries (LIBs) necessitates efficient recycling technologies to recover cathode materials, particularly lithium iron phosphate (LFP), which dominates the traction battery market. Conventional pyrometallurgical and hydrometallurgical methods are energy-intensive and environmentally burdensome. Here, we report a fluorine doping-assisted direct regeneration strategy for spent LFP (SLFP) cathodes, yielding a regenerated LFP-F (RLFP-F) with a hybrid structure of ordered crystalline and disordered domains. Fluorine doping reduces the Li+ diffusion energy barrier, as evidenced by density functional theory calculations, and strengthens Fe–O bonding, suppressing Fe migration and anti-site defect formation. The O 2p band center shifts downward, increasing the Fe 3d–O 2p energy separation from 3.23 eV in pristine LFP to 3.46 eV in RLFP-F, enhancing structural stability and electronic conductivity. Electrochemical tests demonstrate that RLFP-F delivers a high-rate capability and excellent cycling stability. Life-cycle assessment reveals that direct regeneration consumes only 9.986 MJ kg−1 and emits 0.324 kg CO2-equivalent per kg of cell, significantly outperforming pyrometallurgy and hydrometallurgy. Economic analysis based on 2025 Chinese market prices indicates a net profit of $397.15 per ton of SLFP battery recycling, attributed to the closed-loop cathode-to-cathode design. This work provides a sustainable and economically viable route for upcycling spent LFP batteries.