Efficient Simulation of Chemical–Mechanical Coupling in Battery Active Particles

Abstract

Coupling of chemistry and mechanics causes large stresses and deterioration in battery active particles, which undergo a phase change. The Cahn–Hilliard approach coupled to large deformations provides a framework to theoretically investigate the underlying physics. However, solving this model is computationally expensive, so that the current application is limited. In this article, a thermodynamically consistent phase-field model coupling Cahn–Hilliard-type phase separation and large deformations is developed. The model is implemented using a space and time adaptive numerical solution algorithm based on the finite element method. At the example of lithium iron phosphate, simulations are performed to investigate physical and numerical aspects of the model and the solver. The strong interrelation between chemistry, phase transformation, and mechanics is shown. In particular, the interfacial energy coefficient has a major impact on the stress inside the material. Moreover, the presented solution algorithm outperforms classical implementations. This enables the analysis of computationally demanding parameter choices and multidimensional geometries.