Predictive Particle-Based Simulation of the Fabrication of Li-Ion Battery Electrodes

The microstructure of commercially made lithium-ion battery electrodes is not necessarily optimal for cell performance. In an attempt to optimize the performance, detailed understanding of the microstructure is necessary. Factors that influence electrode microstructure include high-level variables such as composition and porosity; as well as detailed fabrication conditions that are part of the film-making, drying, and calendering steps.

Here we report on initial efforts to model the particle-level microstructure of lithium-ion cathodes and how this relates to fabrication conditions. LAMMPS, a molecular simulation code, was adapted for these mesoscale particle simulations. In particular we simulate a cathode composed of irregular-shape active material particles using a superposition of spheres to imitate complex particle shapes and aggregates of carbon and binder. Equations of motion coupled to inter-particle forces are solved to simulate particle motion and subsequent immobilization during fabrication steps.

Both the slurry and dried film are simulated and validated by comparing to experimental results for microstructure, tortuosity, and mechanical properties like viscosity and elasticity. Initial work includes simulations of NCM cathodes. Such simulations are a first step in allowing us to predict electrode microstructure and therefore battery performance from fundamental fabrication conditions.

This work is supported by the U.S. Department of Energy through the BATT program.