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

TL;DR

This paper develops a comprehensive coupled continuum model for battery electrodes that incorporates electrochemical, thermal, mechanical, and porosity evolution effects, providing insights into how intercalation-induced strains affect battery performance.

Contribution

It introduces a novel finite strain framework to model porosity evolution driven by intercalation, thermal expansion, and mechanical stresses in battery materials.

Findings

Porosity evolution significantly influences ion distribution and electrostatic fields.

Dynamic porosity impacts charge-discharge behavior and mechanical forces.

The model predicts large local deformations affecting battery performance.

Abstract

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