Diffusion-Induced Stresses in Transversely Isotropic Cylindrical Electrodes of Lithium-Ion Batteries

Abstract

As novel electrodes of lithium-ion batteries, anisotropic nanocrystal materials with improved electrochemical performance can experience anisotropic swelling and sustain stresses during charging and discharging. However, previous diffusion-induced stress models have rarely considered the effects of anisotropic properties. In this study, an analytical model of diffusion-induced stresses is developed for transversely isotropic cylindrical electrodes during lithiation under galvanostatic operation. The results show that the transversely isotropic stress solutions for cylindrical electrodes can degrade into isotropic stress solutions, and the radial and tangential stresses depend slightly on the Young's modulus ratio and lithiation expansion coefficient ratio of axial direction to isotropic plane, while the axial stress depends strongly on the two ratios. In addition, we introduce two correction factors which establish a bridge between the stress solutions for transversely isotropic electrodes and isotropic electrodes, and further investigate them from two special cases. It is indicated that transversely isotropic electrodes can be designed more flexibly compared with isotropic ones due to tunable anisotropic properties.