Concentration Distribution and Stresses in Porous Electrodes with Particle-Particle Contact

During the charge/discharge cycle or fabrication, stresses which arise from diffusion-induced stress (DIS) and particle-particle contact can cause mechanical degradation or failure of Li-ion battery porous electrodes. Here, we develop a new model of porous electrodes in which shape polydispersity and different contact types are considered. The influences of particle-particle contact, contact types, and shape polydispersity on the concentration profile and stresses were numerically investigated. For only spherical-spherical contact, the Li-ion concentration in the contact region of the particles significantly decreased compared with that in the noncontact region, and there is significant radial stress located near the contact area. For purely elliptical-elliptical contact, the best contact type was obtained with the minimum stress and maximum contact radius. For arbitrary contact with shape polydispersity particles, the Li-ion concentration of pole-spherical contact near the contact point is lower, and equator-spherical contacts have a lower contact stress but higher contact radius. Moreover, contact stresses were dominant over DIS for all studied cases. With the formulation and simulation of the particle direct contact process, this study refines our understanding of the electrochemical-mechanical coupling effect in Li-ion batteries porous electrode.