Intercalation driven porosity effects in coupled continuum models for the electrical, chemical, thermal and mechanical response of battery electrode materials

摘要

We present a coupled continuum formulation for the electrostatic, chemical,thermal and mechanical processes in battery materials. Our treatment applies onthe macroscopic scale, at which electrodes can be modelled as porous materialsmade up of active particles held together by binders and perfused by theelectrolyte. Starting with the description common to the field, in terms ofreaction-transport partial differential equations for ions, variants of theclassical Poisson equation for electrostatics, and the heat equation, we addmechanics to the problem. Our main contribution is to model the evolution ofporosity as a consequence of strains induced by intercalation, thermalexpansion and mechanical stresses. Recognizing the potential for large localdeformations, we have settled on the finite strain framework. We present adetailed computational study of the influence of the dynamically evolvingporosity, upon ion distribution, electrostatic potential fields,charge-discharge cycles and mechanical force generated in the cell.