Modified coatings on metal bipolar plates in proton exchange membrane fuel cells

Metal bipolar plates used in proton exchange membrane fuel cells (PEMFC) are under intensive study due to their excellent processability, good electroconductivity, and excellent thermal conductivity．Production cost and performance of bipolar plates are key to practical applications and to expand their application ranges．Erosion of metal bipolar plates in acidic and humid environment of PEMFC and reduction of contact resistance due to surface oxidation are challenges in their practical application．This paper reviews preparation methods of modified coatings．Coatings used for surface modification (metal-based coatings, amorphous carbon coatings and nitride coatings) are compared in their adhesion strength, interfacial conductivity, corrosion resistance and hydrophobicity．Corrosion mechanisms of modified coatings and factors affecting performance are analyzed．Difficulties in structural design, failure mechanism and element selection of coatings are examined．Reducing costs and improving durability should be emphasized in future research．