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

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.