Research Progress on Surface Modification of Bipolar Plates for Proton Exchange Membrane Fuel Cells

In proton exchange membrane fuel cells (PEMFCss) components, the bipolar plate is the most important part due to its high proportion of the cost, mass and volume of PEMFCs (45%, 80% and 50%). Because of the material and process problems of the bipolar plate, the volume and mass of the traditional graphite PEMFCs are relatively large, which increases the vehicle mass, reduces the available space of the vehicle chassis, and affects the performance of the PEMFCs vehicle. Therefore, the development of a lightweight, low-cost and simple preparation process for the bipolar plate is of great significance to promote its commercial application. The metal bipolar plate has attracted much attention in the PEMFCs field because of its low cost, good mechanical properties, electrical conductivity, thermal conductivity, and relatively easy-to-control volume. However, in the PEMFCs environment, the metal bipolar plate is easy to form a passivation film, which leads to an increase in its contact resistance. Therefore, improving the corrosion resistance of metal bipolar plates and maintaining good conductivity are the main focuses of current research on PEMFCs. The graphite-type, composite, and metal bipolar plate preparation processes or surface modification methods were summarized, and the advantages and disadvantages of bipolar plate or carbide coatings, metal coatings and nitride coatings on surface were discussed. In addition, the corrosion resistance and interfacial contact resistance performance of these coatings under the PEMFCs environment were compared.