Modeling of Chemo-Mechanical Multi-Particle Interactions in Composite Electrodes for Liquid and Solid-State Li-Ion Batteries

Abstract

Modeling of the chemo-mechanical interactions between active particles in battery electrodes remains a largely unexplored research avenue. Of particular importance is modeling the local current densities which may vary across the surface of active particles under galvanostatic charging conditions. These depend on the local, stress-coupled electrochemical potential and may also be affected by mechanical degradation. In this work, we formulate and numerically implement a constitutive framework, which captures the complex chemo-mechanical multi-particle interactions in electrode microstructures, including the potential for mechanical degradation. A novel chemo-mechanical surface element is developed to capture the local non-linear reaction kinetics and concurrent potential for mechanical degradation. We specialize the proposed element to model the electrochemical behavior of two electrode designs of engineering relevance. First, we model a traditional liquid Li-ion battery electrode with a focus on chemical interactions. Second, we model a next generation all-solid-state composite cathode where mechanical interactions are particularly important. In modeling these electrodes, we demonstrate the manner in which the proposed simulation capability may be used to determine optimized electro-chemical and mechanical properties as well as the layout of the electrode microstructure, with a focus on minimizing mechanical degradation and improving electrochemical performance.