One-Pot Direct Recycling of Spent LiCoO₂ via Synergistic Binder Defluorination and Phase Reconstruction

Direct recycling of spent lithium-ion battery cathodes is hindered by two interdependent challenges: persistent polyvinylidene fluoride (PVDF) binder residues that block particle surfaces and incomplete structural repair of degraded layered phases. Here, we report a one-pot regeneration strategy based on a Li⁺-containing deep eutectic solvent (Li⁺-DES) that integrates targeted defluorination and phase reconstruction within a reusable medium. Under mild conditions, the functionalized Li⁺-DES selectively cleaves C─F bonds of PVDF, enabling complete binder removal and interface purification. Without any solvent exchange, the same Li⁺-DES serves as a lithium-rich repair medium, in which enhanced Li⁺ coordination and transport promote the formation of a uniform pre-lithiation layer and facilitate the conversion of inactive spinel Co₃O₄ back into well-ordered layered LiCoO₂ upon annealing. The regenerated LiCoO₂ delivers a discharge capacity of 157.4 mAh g^-1 at 0.1 C, retains 83.1% of its capacity after 300 cycles, and maintains stable cycling even at 4.6 V. By integrating defluorination, Li replenishment, and structural reconstruction into a single reusable system, this work provides a simplified, energy-efficient, and sustainable route for closed-loop recycling of degraded cathode materials.