Over the early decades of the 21st century, lithium-ion batteries have emerged as the leading energy storage technology in portable electronics and electric vehicles. Their popularity can be attributed to their rapid rechargeability and high power density. As demands on lithium-ion batteries increase, particularly from the electric vehicle manufacturers, challenges such as loss of charge capacity over usage must be addressed. Historically, lithium-ion batteries have mainly been studied from a chemical point of view. However, to effectively mitigate charge capacity fade, the mechanical behaviour of the lithium-ion batteries must be understood. 

This thesis aims to deepen the understanding of the mechanical behaviour and degradation of lithium-ion batteries, particularly of the batteries’ positive electrode layers. Using numerical modelling, specifically the discrete element method, a framework for simulating several mechanical aspects of the lithium-ion batteries’ positive electrode layer has been developed, including manufacturing and usage processes, and replicating experimental measurements to determine mechanical properties. These aspects were investigated and linked to the material properties and behaviours of the layer’s constituents as well as usage conditions. The findings offer vital insights into the micromechanical behaviour of positive electrode layers and their dependency on the constitutive behaviour of the layer’s constituents. These insights are significant for future lithium-ion battery development.