A phase field model coupling lithium diffusion and stress evolution with crack propagation and application in lithium ion batteries.

Cracking and fracture of electrodes under diffusion during lithiation and delithiation is one of the main factors responsible for short life span of lithium based batteries employing high capacity electrodes. Coupling effects among lithium diffusion, stress evolution and crack propagation have a significant effect on dynamic processes of electrodes during cycling. In this paper, a phase field model coupling lithium diffusion and stress evolution with crack propagation is established. Then the model is applied to a silicon thin film electrode to explore the coupling effects on diffusion and crack propagation paths. During lithiation, simulation results show that lithium accumulates at crack tips and the lithium accumulation further reduces the local hydrostatic stress. Single and multiple crack geometries are considered to elucidate some of the crack patterns in thin film electrodes as a consequence of coupling effects and crack interactions.