Microstructural characteristics — such as porosity, coordination number, and tortuosity —fundamentally influence energy density and efficiency. However, the underlying mechanics governing the evolution of granular structures during calendaring, a key electrode manufacturing process, remain poorly understood. The interactions between AP and CBD occur at the microscale and evolve rapidly, making direct observation of internal structural variations particularly challenging. Consequently, a deeper understanding of these processes necessitates the use of advanced computational modelling techniques. In this study, we develop a state-of-the-art computational framework based on the material-point discrete-element method (MP-DEM) to simulate the evolution of battery electrode microstructures under external loading. In this framework, active material particles are represented as discrete elements, while the viscoelastic CBD is modelled as a piecewise continuum using the material point method (MPM). By leveraging the strengths of both MPM and DEM, our approach enables accurate simulation of highly heterogeneous granular systems through interactive force exchanges between components. The results provide critical insights into the relationship between microstructural evolution and manufacturing conditions, offering a quantitative foundation for optimizing processing parameters in engineering applications.