The presence of crystal defects, such as dislocations and stacking faults, not only induces large lattice strains but also dramatically modifies the local oxygen environment, which manifests itself through inserting extra lattice planes or perturbing the sequence of the oxygen layers . Density functional theory (DFT) calculations reveal that the formation energy of the oxygen vacancy can be markedly reduced from 1.06 eV to 0.24 eV with applying a 10% tensile strain to the layered oxide cathode . Moreover, stacking faults and dislocations can provide an alternative route to form different disordered structures by offering a greater freedom to the displacement of TM ions into the alkali metal layers . Dislocation-induced irreversible oxygen release and structural degradation is schematically shown in Fig. . This argument is further substantiated by a comprehensive range of characterisations spanning from the atomic to micro-length scale, including HRTEM, Bragg coherent X-ray diffraction imaging (BCDI), and transmission-based X-ray absorption spectromicroscopy and ptychography experiments (Fig. ).