Electrode crack evolution and failure mechanism during calendering: Insights from discrete element method-based mesoscopic simulation

Abstract

The mechanical failure behavior of electrode structures during calendering or compressive loading in lithium-ion batteries (LIBs) is recognized as a crucial factor affecting their safety performance. To gain better insight into the mesoscopic and microscopic mechanisms of electrode fracture, a two-dimensional mesoscopic model of the electrode, including active materials (AMs), carbon-binder domain (CBD), and pores, is proposed based on the discrete element method. This model is designed to analyze crack initiation, propagation, and eventual fracture caused by CBD failure during calendering by linking the local contact of AMs. The effects of the initial electrode structure, AM particle size, particle size distribution (PSD) and electrode thickness on the mechanical integrity of the electrode are also investigated. The simulated crack morphology is found to be in good agreement with the results of the electrode compression tests. It is observed that a narrower PSD and larger particle size contribute to better mechanical integrity. Increasing electrode thickness reduces mechanical integrity. The developed model enhances our understanding of electrode failure behavior at the mesoscopic level and provides a valuable physical and mechanical basis for optimizing the design of electrode manufacturing processes in LIBs.