Discrete element method and electrochemical modelling of lithium ion cathode structures characterised by X-ray computed tomography

Abstract

Electrode microstructure can profoundly affect the performance of lithium-ion batteries. In this work, the effect of the calendering process on electrode microstructures is investigated using the Discrete Element Method (DEM) with a bonded particle model. A comprehensive evaluation between realistic electrode structures and idealised DEM structures as characterised using X-ray computed tomography (XCT) is presented. The electrode structural and transport properties of tomography scans and DEM structures, i.e. porosity distribution, specific surface area and tortuosity factors are studied. Following consideration of the carbon binder domain (CBD) phase, electrochemical analysis is further performed. Excellent agreement between tomography and idealised structures from DEM simulations is achieved, taking into account the effect of calendering. With electrode compression battery performance is improved after calendering. This study provides a basis for using DEM and electrochemical analysis to quantitatively evaluate the battery performance in future.