Improved polymer electrolyte fuel cell performance with membrane electrode assemblies using modified metallic plate: Comparative study on impact of various coatings

Abstract

Bipolar plate is one of the key components of polymer electrolyte membrane fuel cell. In the present study, metallic plates are explored as bipolar plates in comparison to most generally used high-density graphite plates. Among various metals, stainless steel 316L is preferred due to its low cost, high strength, ease of machining and for its corrosion resistance characteristics. However, the challenges associated with metallic plates are high interfacial contact resistance due to passive oxide layer formation and possible corrosion product during operation in chemically harsh environments, which may contaminate the membrane electrode assembly. Three electrically conductive and corrosion resistant coatings namely Titanium Nitrides, Plasma Nitride, and Gold have been coated over the surface of stainless steel 316L metallic plate to overcome these challenges and to explore their impact on fuel cell performance using standard membrane electrode assemblies. These coatings are characterized by X-Ray Diffraction, Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy along with interfacial contact resistance measurements. Further, the coated SS plates have been tested in real time polymer electrolyte membrane fuel cell operation for their use as bipolar plates and their performances have been compared with the fuel cell comprising conventional graphite plates. A cell comprising Titanium Nitride, Gold and Plasma Nitride coated metallic plates exhibit a power density of 430, 720 & 268 mW cm−2 respectively, at an operating fuel cell potential of 0.6 V. Gold coated metallic plate shows comparable polymer electrolyte membrane fuel cell performance in relation to conventional graphite plate.