Scalable Top-Down Approach for Recycling Highly Degraded Spent LiFePO₄ via Lattice Fragmentation-Regeneration

Designing efficient, scalable, and eco-friendly recycling technologies is crucial for addressing the widespread decommissioning of spent lithium-ion batteries. Here, an innovative top-down regeneration method is introduced to rejuvenate highly degraded LiFePO₄. Initially, the crystal structure of spent LiFePO₄ is destroyed via the oxidation process, followed by the reconstruction of the LiFePO₄ lattice through the reduction process. The regenerated LiFePO₄ features a uniform particle size and an intact crystal lattice, leading to substantial improvements in electrochemical performance. Specifically, it achieves a capacity of 142.6 mAh g^-1 at 1 C, significantly surpassing the spent LiFePO₄ (only 55.6 mAh g^-1 at 1 C). Furthermore, it demonstrates an exceptional retention of 86.7% after 450 cycles, in contrast to 55.8% retention of commercial LiFePO₄. More importantly, spent LiFePO₄ with varying degrees of degradation is successfully regenerated using this technology, confirming its scalability. Therefore, this research highlights a transformative and sustainable approach to LiFePO₄ regeneration, achieving splendid advancements in both electrochemical performance and cycle stability, and offers a novel pathway for the effective recycling of LiFePO₄-based energy storage systems.