Diffusion-deformation theory for amorphous silicon anodes: The role of plastic deformation on electrochemical performance

摘要

Amorphous silicon (a-Si) is a promising material for anodes in Li-ion batteries due to its increased capacity relative to the current generation of graphite-based anode materials. However, the intercalation of lithium into a-Si induces very large elastic-plastic deformations, including volume changes of approximately 300%. We have formulated and numerically implemented a fully-coupled diffusion-deformation theory, which accounts for transient diffusion of lithium and accompanying large elastic-plastic deformations. The material parameters in the theory have been calibrated to experiments of galvanostatic cycling of a half-cell composed of an a-Si thin-film anode deposited on a quartz substrate, which have been reported in the literature. We show that our calibrated theory satisfactorily reproduces the mechanical response of such an anode - as measured by the changes in curvature of the substrate, as well as the electrochemical response - as measured by the voltage versus state-of-charge (SOC) response.