The Corrosion Resistance Behaviors of Metallic Bipolar Plates for PEMFC Coated with Physical Vapor Deposition (PVD): An Experimental Study

Abstract

Durability of polymer electrolyte membrane (PEM)-type fuel cells is the most challenging problem preventing commercialization. There are several sources corroding the membrane and the catalyst layer or oxidizing the bipolar plate of fuel cells. There are several reasons for performance drop in PEM-type fuel cells, and degradation of the bipolar plates is one of the most important one. Graphite-based bipolar plates are usually resistant to corrosion, but because of their slow and costly manufacturing process metallic bipolar plates step forward for commercialization. Among other materials, metal nitride-coated stainless steel materials are good candidates for bipolar plate material of commercial applications. In this study, different stainless steel materials, such as 304, 316L, 316Ti and 321, coated with titanium nitride (TiN) and chromium nitride (CrN), using the physical vapor deposition (PVD) method, were tested in terms of corrosion. Corrosion resistance improvement was observed with both TiN and CrN coatings. As the best result, corrosion current value, as low as 0.2 \({\mu}\)A/cm\({^{2}}\), was obtained with CrN-coated SS316Ti specimen. Small titanium and molybdenum content in stainless steel improved the corrosion resistance of CrN coating.