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One-pot compositional and structural regeneration of degraded LiCoO2 for directly reusing it as a high-performance lithium-ion battery cathode

Recycling spent cathodes from Li-ion batteries (LIBs) is an appealing route to address environmental issues and resource shortage, but is plagued by effective and simple recycling techniques. Current recycling technologies generally involve multi-steps such as acid leaching, precipitation, smelting, or solid-state sintering, and obtained products possess inferior electrochemical properties. The current work explores a new regeneration method for failed LiCoO2 cathode material. The electrochemical performance of LiCoO2 is fully recovered through a single thermal-chemical treatment of spent LiCoO2 in molten LiOH–KOH–Li2CO3 under air atmosphere. The molten salt mixture presents suitable dissolving capacity, homogeneous thermal circumstance, abundant Li+, and high ion diffusion rate to decompose impurities, compensate for Li+ deficiency, and repair damaged structure through a “dissolution-recrystallization” mechanism. Under the optimized reaction temperature of 500 °C, the regenerated LiCoO2 possessed similar stoichiometric composition and crystalline structure of commercial LiCoO2. Importantly, the discharge capacity of spent LiCoO2 was recovered from 68.3 mA h g−1 to 144.5 mA h g−1, reaching the original level of commercial LiCoO2. Besides, the regenerated LiCoO2 also delivered superior cycling of 92.5% capacity retention after 200 cycles and excellent rate performance. This work presents an effective and extendable approach to regenerate spent cathode materials to retrieve their electrochemical performance.