Mechanism‐guided direct regeneration of degraded NCM cathodes: From atomic‐scale degradation to structural and electrochemical recovery

As a cornerstone technology for clean energy storage, lithium‐ion batteries confront critical challenges of resource scarcity and environmental impacts from decommissioned cells. This study focuses on the regeneration of degraded nickel‐cobalt‐manganese (NCM) cathodes exhibiting low capacity of 128.33 mAh g −1 at 0.1 C. Through atomic‐scale scanning transmission electron microscopy (STEM) analysis, multiscale degradation mechanisms were systematically revealed: progressive phase transformations from layered structure to rock‐salt and spinel configurations driven by lithium vacancy clustering and transition metal migration, oxygen lattice evolution involving irreversible oxygen release, and mechanical degradation through bulk microcrack propagation and dissolution. Based on these mechanistic insights, LiOH·H 2 O compensation and oxygen‐controlled thermal reconstruction are combined to repair degraded NCM cathodes. Advanced STEM characterization verifies three‐dimensional structural restoration, including phase reversion from rock‐salt/spinel intergrowth to reconstructed layered architecture, oxygen vacancy remediation through lattice oxygen reincorporation, and microcrack healing. The regenerated NCM cathodes achieve exceptional electrochemical recovery, delivering a high reversible capacity of 184.78 mAh g −1 at 0.1 C with restored cycling stability. Those findings provide both fundamental insights into phase transformation dynamics and an industrially viable approach for next‐generation battery recycling technology.