Metal separator of fuel cells coated with highly conductive and highly corrosion-resistant oxide thin films

Abstract

A huge attention is given to PEFCs (Polymer Electrolyte Fuel Cells) for eco-friendly engine of automobiles due to their low operating temperature and high output power. However, lack of low-cost materials with high conductivity and corrosion resistance for metal separators in PEFCs interrupts realizing low-cost ones. We have been focusing on tin dioxide (SnO2) as a candidate material. Stainless (SUS) separators coated with SnO2 thin films play important roles to realize low-cost PEFCs. A mist CVD system was employed to fabricate SnO2 thin films aiming to reduce growth costs of thin films. SnO2 thin films were successfully grown on SUS substrates without cracks or pinholes. An obtained PEFC coated with SnO2 thin films achieved the highest output of 0.377 W/cm2 with endurance of more than 750 hours against consecutive power generation. These results indicate SnO2 coated SUS separators are key structures for realization of low-cost PEFCs.