Electrically conductive LCP-carbon composite with low carbon content for bipolar plate application in polymer electrolyte membrane fuel cell

Lightweight polymer-carbon composites with high specific electrical conductivity at a carbon content below 40 vol.% were developed. The electrical and mechanical properties and the hydrogen permeability of carbon fiber and particle reinforced liquid crystalline polymers were examined. Vectra((R)) A 950, SIGRAFIL((R)) carbon fibers and Vulcan((R)) XC 72 R carbon black were employed. The composites are found to have sufficient mechanical properties and a hydrogen permeability low enough to be utilised as bipolar plate material in fuel cell applications. The density of the new composite is 20% lower than the density of commercial bipolar plates made from carbon reinforced polymeric composite materials, due to the lower carbon content. The current density at 0.5 V in an operating fuel cell is only 20% lower compared to commercial materials with more than 80 vol.% carbon content and meets the requirements for bipolar plate application. (c) 2005 Elsevier B.V. All rights reserved.