Optimization of Conductive Fillers of a Composite Material for PEM Fuel Cell Bipolar Plates

Bipolar plates are necessary components in the current design of polymer electrolyte membrane (PEM) fuel cell stacks. The traditional materials used for bipolar plates are graphite and metal. In this investigation an elastomeric material with different types of conductive fillers is developed to avoid the high machining or coating costs associated with the traditional materials. The conductive fillers investigated here include Cytec thermal graphite fibers, Asbury Carbons PAN AGM 99 fiber, synthetic graphite (4012), natural flake (3763), surface enhanced flake (3775), and different grades of graphite powder (TC 301–305). Some of these conductive fillers were implemented in a two component silicone slurry matrix (RTV 627 by GE) to make a composite material. A bulk electrical resistivity of 0.0310 Ω-cm was achieved for the composite containing 28% by volume DKD fiber and 7% synthetic graphite (Asbury 4012) mixed in the elastomeric matrix.