Microscale Simulations of Drying and Calendering Processes to Manufacture Porous Electrodes

Abstract

Electrodes can suffer from inconsistencies in performance due to heterogeneity in particle arrangements. Manufacturing processes such as drying and calendering significantly alter the microstructure and introduce randomness, making it difficult to predict the final structure of the film, given process inputs. This has a crucial impact on the electrochemical and mechanical properties as well as the ultimate performance and lifetime of the battery [1]. The goal of this work is to analyze the behavior of electrode constituent materials during the drying and calendering steps using a new predictive model of microstructure. We have developed a model to simulate the drying and calendering processes using the open-source Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) [2]. Within LAMMPS, we developed a customization of smoothed particle hydrodynamics (SPH), which solves the Navier-Stokes equations on particles representing both solid and liquid materials present in the electrode film. We present here the development of the model and the resulting microstructure predictions for conventional Li-ion battery electrodes. Results are compared to experimental data where available, including microstructures determined from a new freeze-drying technique. Predicted properties such as effective conductivity and degree of heterogeneity can be used in more coarse-grained models to simulate cell performance.