Modeling diffusion induced stress on two phase lithiation in lithium ion batteries
Abstract Capacity fade induced by chemo mechanical degradation during charge discharge cycles is the bottleneck in the design of high performance batteries, especially high capacity electrode materials. In this paper, a flexible sigmoid function is used to create the two phase electrochemical lithiation profile, describing a sharp phase boundary that separates the pristine core from the lithiated shell of an electrode particle. According to such a phase transition, an analytical solution of the stress evolution is obtained by introducing an electrochemical reaction layer into the plastic model. Finally, based on the theory of diffusion induced stress and the energy principle, we determine the critical thickness of radius of a lithiated layer, at which fracture occurs.