Rate-dependent stress evolution in nanostructured Si anodes upon lithiation

摘要

The development of stress and fracture in Si-based anodes for lithium-ion batteries is strongly affected by lithiation-induced plasticity. Recent experiments indicate that the nature of plasticity of lithiated silicon is rate-dependent. We establish a theoretical model to capture the viscoplastic mechanical behavior of Si anodes during two-phase lithiation. It is demonstrated that the lithiation-induced stress field is determined by the migration speed of the Li-Li_(3.75)Si interface and the characteristic size of the Si anodes. If experimentally measured interface velocity data in Si nanoparticle are available, the mechanistic model can directly predict the rate-sensitive spatiotemporal stress profile, which is hardly measured in experiments.