Direct Recycling of Spent LiFePO₄ Cathodes Through Photocatalytic Correction of Anti-Site Defects.

Abstract

Fe-Li (Fe_Li) anti-site defects, commonly observed in degraded LiFePO₄ cathodes, impede Li⁺ mobility and disrupt the electronic pathways, leading to significant performance degradation in LFP. However, addressing Fe_Li anti-site defects to achieve direct recycling of LFP remains challenging due to Fe high migration energy barriers and the lattice distortions they induce. Here, a feasible strategy is proposed for LFP regeneration by utilizing photocatalysis to reduce the Fe migration barrier. This approach facilitates repositioning disordered Fe atoms to their designated octahedral sites while simultaneously enabling Li⁺ diffusion into the LFP lattice, thus restoring capacity and ensuring cycling stability. The mechanism of the photocatalysis regeneration strategy is comprehensively analyzed through a combination of theoretical calculations, in-depth atomic characterization techniques, and electrochemical evaluations. Notably, this strategy is adaptable to varying levels of Fe_Li anti-site defects in spent LFP. Furthermore, life cycle analysis highlights the substantial environmental and economic benefits of this advanced strategy, making it a promising solution for sustainable lithium-ion battery recycling.