A phase-field study of the effect of local deformation velocity on lithiation-induced stress in wire-like structures

The local deformation velocity due to the volumetric change of electrode during lithiation can have a huge influence on the migration of lithium. In this work, we derive an analytical expression for the local flux induced by the local deformation velocity, and propose a modified Cahn-Hilliard type phase-field model, which takes the local deformation velocity into account, to analyze the lithiation of wire-like electrodes with two-phase reaction under potentiostatic operation. The results show that the local deformation velocity greatly alters the distributions of Li-concentration and stresses, and the interphase position varies with the lithiation time, which is due to that the local deformation velocity hinders the Li migration. The influence of the local deformation velocity is dependent on the initial radius of electrode. The delithiation under potentiostatic operation is also studied; and the results reveal that the local deformation velocity has a slighter effect on the diffusion of lithium compared with that during the lithiation.