Investigating electrode calendering and its impact on electrochemical performance by means of a new discrete element method model: Towards a digital twin of Li-Ion battery manufacturing

Abstract

Lithium-ion battery (LIB) manufacturing optimization is crucial to reduce its CO2 fingerprint and cost, while improving their electrochemical performance. In this article, we present an experimentally validated calendering Discrete Element Method model for LiNi0.33Mn0.33Co0.33O2–based cathodes by considering explicitly both active material (AM) and carbon-binder domain (CBD). This model was coupled to a pre-existing Coarse-Grained Molecular Dynamics model describing the slurry equilibration and its drying and a 4D-resolved Finite Element Method model for predicting electrochemical performance. Our calendering model introduces important novelties versus the state of the art, such as the utilization of un-calendered electrode mesostructures resulting from validated simulations of the slurry and drying combined with the explicit consideration of the spatial distribution and interactions between AM and CBD particles, and its validation with both experimental micro-indentation and porosity vs. calendering pressure curves. The effect of calendering on the electrode mesostructure is analyzed in terms of pore size distribution, tortuosity factor and particles arrangement. In addition, the evolution of the macroscopic electrochemical behavior of the electrodes upon the degree of calendering is discussed, offering added insights into the links between the calendering pressure, the electrode mesostructure and its overall performance.