Development of a Full Layer Pore-Scale Model for the Simulation of Electro-Active Material Used in Power Sources

Abstract

A general pore-scale model was developed which mimics the electro-active layer formation process. The model was used to simulate the active material loading on battery, fuel cell and supercapacitor electrodes. The active layer was reconstructed by coating 108 particles with different interparticle interactions onto a smooth surface. Instead of simulating each generated layers at macro scale, scaling analysis was applied to reduce the complexity of the system. It was shown, that the generated layers belong to the same universality class and can be normalized by a self-affine transformation. The non-linear scaling function, obtained at mesoscale, was incorporated into the macrohomogeneous model to simulate the impact of ultra-low Pt loading on specific activity of fuel cells and of thickness of supercapacitors layers on volumetric capacitance. The analysis of experimental data and modeling results revealed that (measurable) specific activity and volumetric capacitance increase at ultra-low loading, because the surface area in unit volume (or porosity) and the thickness scale differently with loading. Finally a general relationship was proposed, which describes the evolution of volumetric surface area density of fuel cells, batteries and supercapacitor with loading, and can be used to build a bridge between mesoscale morphology and macroscopic simulation.