The Cahn-Hilliard reaction-diffusion equation is employed to describe the electrochemical reaction at the cathode/solid-electrolyte interface, and Li intercalation within the cathode. Li-ion transport inside the solid electrolyte is not considered explicitly since we only simulate (dis)charge processes at constant current. The composite cathode is working under the galvanostatic discharge or charge condition, i.e. a constant Li flux into or out of the NMC secondary particle. A Li occupancy fraction of 0.1 or 0.9 in the NMC cathodes is taken as the stress-free state, respectively. For each primary particle within the secondary particle, the layered structure of the oxide cathode permits Li diffusion exclusively within the basal crystallographic plane, with diffusivity depending on the state-of-charge (Fig. ). To accommodate the anisotropic lattice dimension changes resulting from Li (de)intercalation, misfit dislocations in cathodes are usually generated (Fig. , e), which is described by the crystal plasticity mechanical model . Only isotropic elastic deformation is allowed for the solid electrolyte. While the present study uses the maximum principal stress distribution to analyse contact mechanics problems, the current model does not explicitly account for mechanical fracture. (3) The impact of lattice strain resulting from dislocations on oxygen deficiency in the NMC cathode can be assessed via calculating the formation energy of oxygen vacancies under an applied mechanical strain (Fig. ). Atomic-scale calculations reveal that the formation energy of oxygen vacancies in layered oxide cathodes is significantly reduced when the applied tensile strain approaches 10% .