Regeneration of Degraded LiCoO2 from Spent Batteries: Efficient Acid Leaching and Structure Modification for Enhanced Energy Storage

Electrochemical performance of regenerated LiCoO₂ is important for its utilization. Herein, the structure of LiCoO₂ was controlled during its regeneration from spent lithium-ion batteries. The mechanism for adjusting the structure of regenerated LiCoO₂ is investigated. The relationship between LiCoO₂ and its electrochemical performance is discussed. The dissolving capacity of Co²⁺/Li⁺ ions and the final pH of the leachate are considered during the leaching process. The (111) plane of Co₃O₄ is accelerated by precipitating Co²⁺ ions with NaOH and calcining the precipitate at a low temperature (400–500 °C). It is beneficial for developing the (001) plane of LiCoO₂ and improves its electrochemical performance. The optimized LiCoO₂ achieves an initial capacity of 153.4 mA h·g^–1 at 0.5 C with 89.0% capacity retention after 150 cycles. The concentrations of Li⁺/Co²⁺ ions reach 6.6/54.8 g·L^–1, and the final pH is 2.18. This work provides an effective strategy to prepare regenerated LiCoO₂ with a high performance.