Multiscale electrical contact resistance between gas diffusion layer and bipolar plate in proton exchange membrane fuel cells

The contact resistance between gas diffusion layer and bipolar plate in a fuel cell stack is calculated through multiscale contact analysis, which deals with rough surfaces dependent on scales. The rough surface according to scale shows that the surface parameters vary with scale, leading to inaccurate contact resistance. A numerical model is established to reflect the contact interaction of carbon graphite fiber in the contact interface. Two separate analyses are performed, static analysis to determine the contact area and electrical conduction analysis to calculate the electrical contact resistance. Results show that the contact area decreases and the corresponding contact resistance increases as the scale decreases. To accurately estimate the contact resistance, an asymptotic contact resistance according to scale variation is predicted using error analysis. The computed contact resistance is validated via comparison with previously reported values.