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

Electrochemical performance of regenerated LiCoO 2 is important for its utilization. Herein, the structure of LiCoO 2 was controlled during its regeneration from spent lithium-ion batteries. The mechanism for adjusting the structure of regenerated LiCoO 2 is investigated. The relationship between LiCoO 2 and its electrochemical performance is discussed. The dissolving capacity of Co 2+ /Li + ions and the final pH of the leachate are considered during the leaching process. The (111) plane of Co 3 O 4 is accelerated by precipitating Co 2+ ions with NaOH and calcining the precipitate at a low temperature (400–500 °C). It is beneficial for developing the (001) plane of LiCoO 2 and improves its electrochemical performance. The optimized LiCoO 2 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 + /Co 2+ 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 LiCoO 2 with a high performance.