Mesoscale Models for Mechanics of Active Materials in Li-Ion Batteries
We are using recently measured  microstructures of different lithium nickel manganese cobalt oxide (NMC) cathode configurations. The microstructures were determined by X-ray tomography under various pressure conditions. The experimental data on microstructure for increasing pressure is particularly convenient for identification kinematic mechanisms of deformation and formulation of interaction models between particles in electrodes. We use these reconstructed microstructures to generate computational models and to correlate the models to the experiments. Discrete element particle-based methods are used for modeling of mechanics of electrode materials at mesoscale where the meso-scale effects dominate the through-thickness response. Individual particle response can be decoupled from the assembly response and analyzed individually for possible non-linear deformation, fracture, crushing or crumbling. In this work we concentrate on the particle models that use particle size, shape, spatial distributions and inter-particle bonding. Various computational models for the microstructure are used in this study.
An example of a reconstructed battery electrode microstructure with weight ratio of 90:5:5 (active material : C : binder) and the mechanical compression simulation for the equivalent spherical particle model is shown in the figure below . The effects of postulated deformation mechanisms and their parameters are compared with the measures of microstructure configuration at increasing pressures. The developed models are used for modeling the mechanics of active materials in a computational framework for physics-based models of batteries .
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