Diffusion-induced stress and volumetric expansion under potentiostatic operation are investigated with an axisymmetric finite element model taking account of plastic yielding, coupling effects between diffusion and stress, diffusion from the edge surface, and concentration dependence of material properties. Significant differences on stresses, displacements, and fracture energies between purely elastic and elastic–plastic materials are found. Plasticity based on von-Mises criterion has no effect on concentration variation. The critical regions for fracture are the edge surface, and the regions near the edges on both the top surface and the interface.