Resistivity of elastic separator used in PEFC and evaluation of contact resistance between separator and electrode sheet

It has been required to make the separator for the polymer electrolyte fuel cell (PEFC) elastic from the point of view of cost and size. Resistivity of the composites made of ethylene-propylene-diene rubber, carbon black and graphite particle have been studied as a candidate of the separator. The lowest resistivity in the composites is about 20 times larger than that of a promising nonelastic separator. However, it has been concluded that the composites may be capable of being used as a separator if the resistivity is reduced by several fractions because the elastic composite is possible to be made in thinner than the non-elastic composite. It is also concluded that the contact resistance between carbon sheet as an electrode and composite as a separator in PEFC is much larger than the resistance of the composite itself.