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.