Interfacial Morphology and Contact Resistance Model for Polymer Electrolyte Fuel Cells

The imperfect interface between the catalyst later (CL) and micro porous layer (MPL) in a polymer electrolyte fuel cell (PEFC) results in interfacial gaps which can be considerably larger than the pores in the bulk CL and MPL. This leads to an electronic resistance and a potential pooling location for liquid water resulting in mass transport losses. In this study, an analytical model representing the CL|MPL interface under compression is developed to estimate the electrical contact resistance and to elucidate the effect of the initial surface morphology on the contact resistance and interfacial void volume. The results show that the local compression pressure, elasticity of the diffusion media and surface morphology of the mating materials are the key factors controlling the CL|MPL interfacial contact. This micro-contact model not only strengthens our understanding of the CL|MPL interface, but once integrated with a macroscopic fuel cell model, can be used to more accurately predict fuel cell performance.