Interfacial Metal-Solvent Chelation for Direct Regeneration of LiFePO4 Cathode Black Mass

Abstract

Direct regeneration of spent lithium-ion batteries presents a promising approach to effectively reuse valuable resources and benefit the environment. Unlike controlled laboratory conditions that commonly facilitate impurity purification and minimize structural damage, the LiFePO₄ cathode black mass faces significant interfacial challenges, including structure deterioration, cathode-electrolyte interphase residues, and damage from storage procedures, which hinder lithium replenishment and structure regeneration. Here, a metal-solvent chelation reaction using a lithium acetylacetonate solution is introduced to address these challenges under ambient conditions. This method regulates the near-surface structure through strong chelation between Acac^‒ anions and Fe (III) elements, thus effectively eliminating the degraded amorphous phase and residual fluorine compounds. By direct lithium connection and reducing diffusion barriers, the reconstructed surface facilitates the re-lithiation process. The regenerated LiFePO₄ cathodes demonstrate a capacity retention of 88.5% after 400 cycles at 1 C, while also outperforming traditional recycling methods in terms of environmental and economic benefits. This approach provides a promising solution for regenerating degraded LiFePO₄ cathodes from actual dismantled black mass, thereby accelerating the practical application of battery recycling.