Selective oxidative leaching of Li⁺ and utilization of FePO₄ for regeneration of LiFePO₄ cathode material

The recycling and regeneration processes of spent LiFePO₄ (SLFP) batteries have become a research hotspot due to their significant environmental and economic value. Current industrial recycling strategies for SLFP predominantly focus on improving lithium leaching rates, while paying less attention to the resulting ferric phosphate (FePO₄) solid residues, leading to the waste of iron and phosphorus resources. Herein, we propose a closed-loop process for selectively leaching lithium (Li) from spent LFP batteries and regenerating new LFP cathode materials using the FePO₄ from leaching residues. The spent LFP powder is co-ground in a combined hydrogen peroxide-citric acid (H₂O₂-H₃Cit) solution system, with mechanical activation-assisted oxidative leaching, to achieve effective separation of lithium and iron under optimal conditions. The recovered FePO₄ was purified and used to prepare new LiFePO₄ cathode materials. The regenerated LiFePO₄ materials show good electrochemical properties, with the discharge capacity of 144.42 mA h g⁻¹ at 1 C and the capacity retention rate of 95.94 % after 200 cycles. After undergoing high-rate charge/discharge at 5 C and returning to 0.1 C rate, the discharge specific capacity remains stable at 127.24 mA h g⁻¹. A closed-loop process route for spent LFP batteries consisting of "pretreatment-selective oxidative leaching-lithium carbonate and ferric phosphate (Li₂CO₃+FePO₄)-regenerated LFP material" is established and it provides a reference idea and practical experience for the high-efficiency closed-loop development of LFP batteries.