Direct Regeneration of NMC622 Cathode Material from Spent Ev Li-Ion Batteries via Hydrothermal Relithiation

With the increasing demand for electric vehicles, there is a need to address the issues associated with the increasing number of waste Li-ion batteries. In this study, a facile hydrothermal relithiation method, followed by post-annealing, was explored to repair the structure, morphology, and composition of spent NMC622. Based on the XRD pattern, the regenerated NMC622 annealed at 800°C can be indexed similarly with that of pristine NMC622 without any observable impurities. It also showed less agglomeration, with a narrower particle size distribution than the as-recovered spent NMC622. The results suggest that a desirable structure and morphology have been successfully obtained after regeneration. Notably, the results from ICP-OES and XRF analyses further indicate that the Li content of regenerated NMC622 increased from 6.99 to 7.20 wt%, a value close to the theoretical Li composition (7.16%).