Adsorption-Mediated Interfacial Engineering for Direct Regeneration of Spent LiFePO₄ Cathodes

The rapid growth of the electric vehicle industry has led to a large accumulation of lithium-ion batteries. Direct regeneration of spent cathode materials is a promising recycling strategy, yet its industrial application is often constrained by the energy-intensive processes required for lithium replenishment and structural repair under harsh conditions. In this work, the uniform and lithium-rich layer is constructed on the surface of spent LiFePO₄ (S-LFP) via the spontaneous adsorption of organic lithium carboxylate salts. This tailored interface serves as an ideal precursor state for the subsequent thermal annealing step, enabling the synergistic completion of the lithium insertion into the lattice and effective defect healing. This adsorption-mediated interfacial engineering is pivotal to the whole regeneration process. The regenerated LFP (R-LFP) exhibits favorable electrochemical performance, delivering a high specific discharge capacity of 145.5 mAh g^-1 at 1.0 C and retaining 88.1% of its capacity after 400 cycles. Compared with conventional one-step solid-state methods, this hybrid approach reduces overall energy consumption and presents a compelling, scalable pathway for the direct regeneration of S-LFP, thereby advancing the development of sustainable and cost-effective battery recycling solutions.