Effects of particle shape and concurrent plasticity on stress generation during lithiation in particulate Li-ion battery electrodes

A phase field model is developed to investigate the influences of microstructure and concurrent plasticity on the stress development in particulate Li-ion battery electrodes during two-phase lithiation. The model introduces one static order parameter to describe the arbitrary morphology of the particulate electrode and other evolving order parameters governed by the kinetic equations for lithium diffusion and elastoplastic deformation, respectively. The mechanism for the transition from surface hoop compression to surface hoop tension observed in spherical electrodes during lithiation is reexamined using numerical simulations. Our results further show that when the electrode is non-spherical, the combination of large size ratio, large curvature and low yield stress facilitates the transition. In addition, numerical simulations demonstrate that the current model is capable of predicting evolutions of lithium concentration, stress and plastic zone in the electrode with interconnected multi-particle configuration.