Direct Regeneration of Spent LiFePO₄ Cathodes by Liquid-Phase-Mediated Reconstruction

Directregeneration of spent LiFePO₄ (S-LFP) cathodes is imperative for sustainable battery recycling, yet it remains severely hindered by inherent structural degradation, specifically lithium depletion and irreversible Fe³⁺ formation. Herein, we propose a facile, one-step liquid-phase mediated method to directly repair S-LFP. By constructing a liquid-phase-mediated system comprising Fe/Li-based salts and sucrose, this method kinetically accelerates ionic diffusion and ensures homogeneous elemental distribution at a low temperature (300 °C). Concurrently, the synergistic effect of the liquid-phase-mediated state and a reducing atmosphere facilitates the complete structural restoration from Fe³⁺ to electrochemically active Fe²⁺. Consequently, the regenerated LFP (R-LFP) demonstrates exceptional electrochemical reversibility, delivering a superior initial capacity of 158.5 mAhg^-1 at 0.1 C. Notably, practical full-cell evaluations exhibit robust long-term cycling stability, retaining 80.0% capacity over 1500 cycles at a high rate of 2 C. Techno-economic analysis confirms that this low-cost, liquid-phase-mediated regeneration protocol outperforms conventional hydro/pyrometallurgical routes, establishing a viable, scalable closed-loop LFP recycling pathway.