In this study, material domains with a plastic shear exceeding 12% in cathode particles after discharge are categorized as the oxygen-deficient phase. This threshold is determined based on the atomic-scale calculations and by fitting the predicted distribution of oxygen-deficient phase in the secondary particle to experimental characterisation (Fig. ) . The formation of such an oxygen-deficient phase in cathode particles will impede the Li-ion intercalation pathways within the cathodes for the subsequent cycling. We assume that the cathode particle is fully delithiated and lithiated when the average Li occupancy in the cathode is 0.1 and 0.99, respectively.