Surface Treatment of Titanium for Fuel Cell Bipolar Plates

PEFC (polymer electrolyte fuel cell) metallic bipolar plates have attracted much attention because of their thermal and electrical conductivity, gas impermeability, mechanical strength, and ease of manufacturing compared to high-density graphite. Titanium also exhibits these properties but the electrical conductivity is decreased in fuel cell environment due to the growth of surface passive film. Generally, metal bipolar plate surface is coated by a noble metal, carbon or another material. However, these are high cost due to using expensive materials or process. This study introduces a low cost production method of a high performance titanium bipolar plate. The method consists of pickling and heat treatment and enables to produce bipolar plate with a specific thin film on the surface. The film formed on the titanium sheet was investigated by transmission electron microscope. The electrical conductivity was measured by contact resistance with carbon paper after endurance test in simulated fuel cell environment. These results indicate that the material produced by our method exhibits both high conductivity and corrosion resistant. It is expected to be utilized as a bipolar plate for PEFC.