New metal separators coated with carbon/resin composite layers for PEFCs

A new design of metal separator coated with corrosion-resistive and electronically conductive carbon/resin composite layers has been developed. A stainless steel flat plate was coated with a thin composite layer, followed by a formation of ribs of the similar composite on the layer as the gas flow field. We found that the electric conductivity was improved by blending carbon fiber with Ketjen black in the carbon/resin composite. The lowest resistivity of 20.6 m Omega cm was obtained at total carbon content of 50 vol.% with blend ratio of the carbon fiber of 75 vol.%. The composite exhibited a good stability in hot water at 90 degrees C for 2000 h, releasing very small amount of ionic impurities.