Development of carbon fabric/graphite hybrid bipolar plate for PEMFC

The bipolar plates have several functions in Proton Exchange Membrane Fuel Cell (PEMFC); separating flow channels between gases, connecting electrical paths between cells in series and providing structural supports for the stack. Although the carbon fiber epoxy composite bipolar plates recently developed, have high specific stiffness and strength, they have relatively high electrical resistance compared to graphite bipolar plates due to their high surface electrical contact resistance, which requires additional surface treatment such as graphite layer coating. In this research, a new manufacturing method for the carbon fabric/graphite hybrid bipolar plate which consists of two carbon fiber fabrics and an expanded graphite foil liner between them, has been developed in order to increase the productivity of PEMFC and reduce its manufacturing cost by exposing bare carbon fabrics to decrease the surface electrical contact resistance of bipolar plate. Phenolic resin was chosen rather than epoxy resin for the matrix material to decrease both material cost and manufacturing time, and the optimum areal density of phenolic resin was determined experimentally. Also the corrosion resistance, electrical contact resistance and mechanical properties of the hybrid bipolar plates were measured.