Direct regeneration of spent LiNi0.5Co0.2Mn0.3O2 cathodes with Nb-doped for high-performance lithium-ion batteries

The recycling of spent lithium-ion batteries (LIBs) is crucial for environmental protection and resource reutilization. However, traditional recycling routes normally involve complex processes and secondary pollution. In this study, we demonstrate an effective method combining hydrothermal relithiation with low-temperature thermal annealing to directly generate the spent LIBs. We create a lithium-rich environment for spent LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) cathode particles using LiOH solution, followed by surface-doping Nb elements on the active particles for enhanced electrochemical performance. The upgraded NCM523 exhibits a satisfactory repaired specific capacity of 150 mAh g −1 and excellent cycling stability by retaining 75.3% of its capacity after 200 cycles, owing to the stable Nb-doped structure. Hydrothermal relithiation combined with short thermal annealing reduces the temperature and time required for direct regeneration and shows priority in techno-economic and environmental analysis, which can be extended to regenerate spent LiCoO 2 (LCO) cathode. This simple and efficient treatment expands the feasibility of direct regeneration and offers a promising strategy for regenerating spent LIBs.