Manufacturing Impact on Electrochemical and Mechanical Performance of NMC Cathodes Via Mesoscale Simulation

Abstract

Lithium-ion battery performance is determined by numerous coupled multi-physics effects which can be tuned through various manufacturing methods. Electrode calendering pressure can compress local mesostructures, shortening conductive pathways and introducing contact points where mechanical stresses manifest. The addition of a secondary conductive binder phase alters ionic and electronic conduction pathways, limits available surface area for reaction, and buffers mechanical contacts. Coupled physics simulation can visualize localized behaviors that arise from altering these macroscale conditions.Here, we use a mesoscale simulation approach to explore the influence of manufacturing conditions on the performance of an NMC333 half-cell. Image-based particle representations are combined with the Conformal Decomposition Finite Element Mesh (CDFEM) algorithm to provide a conformal, solvable mesh for coupled electrochemical/mechanical simulations. Resolution at this particle scale allows analysis of localized phenomena dependent on particle size, shape, and local mesostructure. Our discussion will detail the limiting physics and variations across domains of four different calendering pressures (0, 300, 600, 2000 bar) and conductive binder fraction (90, 92, 94, 96wt% active material). Per-particle analyses will quantify differences between mesostructures and discuss how local variations influence macroscale properties like cell pressure, effective conductivity, and the discharge curve. Furthermore, we will discuss the statistical effects of domain sample selection on electrode-scale behaviors. This mesoscale analysis allows us to isolate the most significant limiting factors for discharge performance, providing suggestions for future battery design.Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.