Contact mechanics approach to determine contact surface area between bipolar plates and current collector in proton exchange membrane fuel cells

A significant portion of the power loss in a fuel cell stack can be attributed to the contact resistance between the gas diffusion layer/bipolar plate and the current collector/bipolar plate interfaces, especially when an oxide layer is formed on a stainless steel bipolar plate. Researchers have already studied methods to decrease the contact resistance between fuel cell components, but never has a theoretical contact mechanics model been applied to contact resistance problems in fuel cells. Therefore, the purpose of this research is to utilize a theoretical contact mechanics model in order to study real contact area in fuel cell components as a function of surface roughness, material properties, and clamping force. Specifically, the effects of bipolar plate surface roughness, coating thickness of the gold plating on the current collector, and the clamping force on real contact area have been studied. It was found that smoother materials, thicker gold coating, and higher clamping force resulted in a higher real percentage contact area.