Finite element analysis of lithiation-induced decohesion of a silicon thin film adhesively bonded to a rigid substrate under potentiostatic operation

Insertion-induced stress and interfacial decohesion are studied for a silicon thin film adhesively bonded to a rigid substrate under potentiostatic operation. An axisymmetric finite element model with traction-separation law governing the interfacial degradation is used to study the highly nonlinear diffusion-induced volumetric expansion. Plastic yielding of the film, coupling effects between diffusion and stress, diffusion from both the edge and the top surfaces, and concentration dependence of material properties are considered. It is found interface fails in shear mode, and interfacial decohesion initiates at the interface corner and propagates toward the center. A smaller yield stress of the film is beneficial to structural integrity. The side surface and the top surface near the corner are the critical regions for fracture.