DEM simulation of solid-electrolyte separator and cathode densification using a stress-based multi-contact elasto-plastic model

Advancements in high-performance all-solid-state batteries (ASSBs) rely on achieving high relative densities of separators and cathodes to enable efficient ionic and electronic transport. Integrating experiments with DEM simulations provides a particle-scale analysis of microstructure evolution, contactnetwork formation, and force response. Predicting densification via DEM is challenging because conventional DEM treats particles as rigid bodies with soft local contacts, which becomes inaccurate as porosity decreases and contact networks become highly constrained. Moreover, capturing the coupled effects of high plasticity and evolving contact area during compaction remains difficult. In this work, we introduce a modeling framework to simulate densification of ASSB cathodes and separators by integrating an elasto-plastic contact model with plastic contact-deformation approaches that overcome local-contact assumptions through non-local force calculations using stress-based multi-contact formulations. The model is compared with the Hertz contact model, Thornton-Ning elasto-plastic model, and experimental data for both unimodal and bimodal PSDs. Simulations at higher load levels show that our contact model captures stronger nonlinearity in higher stress regions and improves agreement with experiments in the dense regime. This approach enables predicting different compaction pressures during cell assembly and cycling, helping to identify suitable processing parameters that enhance the electrochemical properties of the components.