A developed expression of chemical potential for fast deformation in nanoparticle electrodes of lithium-ion batteries

Abstract

Abstract In this paper, we propose a developed expression of chemical potential without the assumption of low deformation rate to account for the diffusion induced stress and the distribution of Li concentration in nanoparticle electrodes of lithium-ion batteries. The difference between the developed and traditional expressions on the stress evolution in a spherical nanoparticle electrode made of silicon is analyzed under both potentiostatic and galvanostatic operations, using the derived diffusion equation and the finite deformation theory. The numerical result suggests that the difference between these two expressions of chemical potential is significant under potentiostatic operation, rather than that under galvanostatic operation. A critical radius, where there is no difference between the Li flux caused by these two expressions of chemical potential as well as the Cauchy hydrostatic stress during most of the lithiated process, is firstly reported in this work.

Keywords

• Chemical potential
• Fast deformation
• Diffusion-induced stress
• Lithium-ion batteries