Comparative review of corrosion-resistant coatings on metal bipolar plates of proton exchange membrane fuel cells

In the realm of proton exchange membrane fuel cells (PEMFCs), the bipolar plates (BPs) are indispensable and serve pivotal roles in distributing reactant gases, collecting current, facilitating product water removal, and cooling the stack. Metal BPs, characterized by outstanding manufacturability, cost-effectiveness, higher power density, and mechanical strength, are emerging as viable alternatives to traditional graphite BPs. The foremost challenge for metal BPs lies in enhancing their corrosion resistance and conductivity under acidic conditions, necessitating the application of various coatings on their surfaces to ensure superior performance. This review summarizes and compares recent advancements in the research of eight distinct types of coatings for BPs in PEMFCs, including noble metal, carbide, nitride, and amorphous carbon (a-C)/metal compound composite coatings. The various challenges encountered in the manufacturing and future application of these coatings are also delineated.