Development of Conductive and Anticorrosive Paint Dispersed with Carbon Particles for Metal Separators of PEFC

A resin paint dispersed with carbon particles was developed for the purpose of good conductivity and corrosion resistance for metal separators used in Polymer Electrolyte Fuel Cells (PEFC). The use of metal separators, especially Ti separators is a technology which has received much attention for its practical application as it allows for much greater compact stacking, since it is superior in both productivity and strength, in comparison with that of carbon molding separators. However, if pure Ti separators are used in a severe reaction of electricity generation, there is a deterioration in conductivity, because of the formation of a passive film, which subsequently causes electricity generation difficulties after a few hours of use. Through examining the type of resin used for the purpose of controlling the passive state, the grain size of the conductive filler (graphite (Gr) + carbon black (CB)) and the composition combination for the purpose of secure conductivity, it was found that the combination of a scaly graphite-furnaced black mixed powder with a median particle diameter of 4μm and VDF-10%HFP copolymer resin was optimal. As a result of performing a single cell electricity generation evaluation of the Ti separator, which had the above mentioned coating material, the life of 22,000 or more hours was confirmed and an electricity generation evaluation is now being undertaken.