A mechanistic model for electrical contact resistance at the GDL–BPP interface

Abstract

The high electrical contact resistance (ECR) at the interface between the carbon-paper gas diffusion layer (GDL) and the metallic bipolar plate (BPP) is a limiting factor in proton exchange membrane fuel cells (PEMFCs). This work proposes a numerical framework that quantifies the ECR as a function of the morphology of the surface, the effective contact strength, and the effective interfacial resistivity of the contacting materials. GDL microstructures are realized using a stochastic reconstruction method, while realistic BPPs are generated with various rough surfaces. The mechanical deformation of the GDL–BPP interface is simulated for different external pressures and then the ECR is calculated. The proposed model is validated against four independent experimental studies, achieving coefficients of determination between 0.88 and 0.97. Thus, this physics-based contact model provides the pressure-dependent ECR with high accuracy, and hence represents an effective and simple numerical tool for optimizing the GDL–BPP interface when designing PEMFCs.