Closed-Loop Regeneration of a Spent LiFePO₄ Cathode by Integrating Oxidative Leaching and Electrochemical Relithiation

The explosive growth and limited lifespan of lithium-ion batteries (LIBs) have brought about the concomitantly exponential generation of end-of-life LIBs, thus stimulating considerable enthusiasm for the innovative recycling and regeneration of spent cathode materials to alleviate the shortage of lithium resources and address environmental pollution issues. Herein, a facile closed-loop regeneration strategy is proposed to recover the spent LiFePO4 (LFP) cathode materials. Specifically, the LFP electrode leftovers are oxidized by ammonium persulfate to generate FePO4 and aluminum foil, and lithium-containing leaching solution, which can be directly utilized as an electrolyte for in situ electrochemical relithiation of spent LFP cathodes, achieving the effective closed-loop up-cycling between electrode leftovers and spent LFP cathodes. The effects of lithium-containing solution concentrations and applied current densities on the microstructure and compositions of the regenerated LFP cathodes are systematically studied. Furthermore, the electrochemical performance of the regenerated LFP cathode is evaluated in half-type coin cells. Under the optimized operating conditions, the regenerated LFP cathode exhibits an excellent discharge capacity of 154.2 mA h g–1 at 0.5 C and a capacity retention rate of 91.0% after 300 cycles at 1 C. This work provides an innovative perspective for the regeneration of spent LIBs by utilizing the electrode leftovers as alternative lithium resources to achieve the relithiation of spent LFP cathodes, promoting the sustainable development of the LIB industry.