Effects of stoichiometric maximum concentration on lithium diffusion and stress within an insertion electrode particle

摘要

Active materials for either anode or cathode have a stoichiometric upper limit of lithium intercalation. To investigate the effects of stoichiometric maximum concentration (SMC) on the lithium diffusion and diffusion induced stress, we establish an analytical model and compare with existing results. We show that SMC not only facilitates lithium diffusion, but also significantly relieves the maximum stress and its corresponding peak value during lithium insertion, and therefore, declines the probability of fracture in the electrode particle. Moreover, the effect of SMC is found to be more obvious for higher surface current density or lower stress coupling due to the significant concentration gradient of lithium. Finally, by investigating the combined effect of current density and stress, this work provides insights on the presence of SMC, as well as suggestions for the relevant modeling works on whether the SMC should be taken into account for material selection and designing.