The electrical and physical properties of alternative material bipolar plate for PEM fuel cell system

Abstract

The bipolar plates in polymer electrolyte membrane fuel cells (PEMFC) typically have been made of polymer resin-impregnated graphite. However, because of their expensive cost and for difficulties to design the gas flow field channels to machine, it should be considered to search out the alternative materials from graphite to carbon–carbon composite and carbon–polymer composites. Therefore, several kinds of composite plates for PEMFC are currently under development to easy produce and reduce cost, stack volume and weight. In this work, we present the preparation method and characterization of alternative bipolar plate material, which can be researched for the application of PEMFC vehicle. Bulk resistance of the plate was measured with a four-point probe method. The electrical conductivity of polymer composite plate was 4.40 × 10 3 S/cm. On the other hand, the electrical interfacial resistance of the polymer composite plate valued at 1.87 mΩ cm 2 and that of graphite was 0.26 mΩ cm 2 under the holding pressure of 140 N/cm 2 at the applied current of 5 A. And the performance of alternative materials bipolar plate for PEMFC with 25 and 50 cm 2 were evaluated at various conditions. The single cell performance was more than 0.37 W/cm 2 (0.77 W/g) for polymer composite bipolar plate at 50 °C under atmospheric pressure in external humidified hydrogen and oxygen condition. As the results, we could show the results that the alternative material bipolar plates were favorable in the aspect of electrical and physical properties compared with those of the commercialized resin-impregnated graphite plates.