A combined X-ray computed tomography and discrete element method study on the thermo-mechanical behavior of cathode during calendering

Calendering plays a pivotal role in lithium-ion battery manufacturing, as it critically governs the electrode's density, thermal conductivity, and mechanical integrity, thereby affecting its processability and overall electrochemical performance. This study presents an integrated 3D thermo-mechanical coupling framework that combines in-situ compression testing, X-ray computed tomography (X-CT), and discrete element method (DEM) simulations based on realistic electrode microstructures. By using this framework, a comprehensive investigation on the evolution and interactions of particle contact networks, fabric tensors, and thermal transport properties during electrode compaction is conducted. The results demonstrate a logistic-type nonlinear increase in effective thermal conductivity with calendering pressure, axial stress, and fabric tensor deviator magnitude, while decreasing with electrode thickness. Furthermore, the fabric tensor deviator shows a strong quadratic correlation with both external pressure and thickness, highlighting its sensitivity to structural anisotropy and critical role in thermal conduction pathway formation. As a structural descriptor, the fabric tensor deviator effectively bridges the microscale contact rearrangements and macroscopic thermal performance. Additionally, the study uncovers a distinct “initial-growth-saturation” evolution pattern in the development of thermal pathways during calendering. These findings offer valuable theoretical insight and modeling guidance for optimizing electrode structure and calendering strategies in advanced battery manufacturing.