There is an ongoing transition from fossil fuels toward electric vehicles powered by lithium-ion batteries. This transition necessitates significant improvements in battery lifetime, capacity, and cost efficiency. Understanding and accurately predicting the battery degradation mechanisms, including state-of-health (SoH) evolution, swelling (both reversible and irreversible), and mechanical stresses under realistic conditions, are central to extending battery lifetime and optimising design. Encapsulations of battery cells into packs and modules may, in addition, lead to heterogeneous states of stress, temperature, and other electrochemical variables that can result in local variations in capacity retention (state of health). Incorporating mechanical and thermal phenomena, coupled with electrochemical processes, yields more realistic lithium-ion battery models but significantly increases computational complexity and cost, especially when the focus is on modelling battery modules and packs. The main objective of this study is to bridge the gap between an accurate representation of the stress state and computational costs. A continuum-level finite element model (FEM) that simulates mechanical stress evolution in battery electrodes, cells, and modules has been developed. The model employs continuum-shell elements to represent the layered structure of a cell, capturing detailed layer deformations and cross-layer interactions with a pointwise resolution of strain across each layer. The electrodes' swelling behaviour and interactions with the neighbouring layers are captured. Thus, more realistic indicators for the degradation of the cells are considered, with viable computational costs, especially when considering the battery module and battery pack scale, which are of interest to the industry.