Lithium-ion batteries experience charge capacity loss during their lifecycle caused by mechanical phenomena. In this study, a discrete element method (DEM) simulation model, to link the local mechanical behaviour in the positive electrode active layer to its global mechanical properties, was developed. DEM is a suitable method to use as the electrode active layer has a granular structure and the model includes contact formulations for the active particles and the binder domain. Simulations of the calendering process and the measurement of the active layer's global mechanical properties is possible with the framework. The model developed can capture the pressure sensitivity of the active layer, which has been observed in experiments.

Mechanical degradation mechanisms are one of the leading causes of charge capacity loss in lithium-ion batteries. This study further develops a discrete element method (DEM) simulation framework, which investigates how the local contact behaviour affect the global mechanical properties of the active layer. The local microstructure consists of active particles held together by a binder domain, making up a granular medium. This study investigates the impact of the layer's global properties from the type of particle contact model. Experiments were also performed to measure size distribution and the material properties of the active material. The time dependency of the active layer, stemming from the viscoelastic binder domain, was studied in relaxation simulations, which were based on experimental measurements.

Mitigating the loss of charge capacity is one of the main challenges in developing lithium-ion batteries. Mechanical degradation is one of the causes of charge capacity loss, and insight into these processes is necessary for battery development. This study uses a discrete element method (DEM) framework to model the mechanical properties of a positive electrode active layer. In particular, how the active layer properties are affected by the volumetric change and material degradation of the active material linked to charge cycling. The results show a stiffening of the active layer following charge cycling, stemming from the volumetric expansion of the active particles. These results agree with trends seen in experimental measurements.