.FIG. 1 is a perspective view of a fuel cell developed at the University of Oakland that does not need gaskets for use with the bipolar plates.
A new elastomeric conductive bipolar plate for use in proton exchange membrane fuel cells that reduces the weight of the fuel cell and eliminates the need for gaskets typically used in these fuel cells has been manufactured by Oakland University (Rochester, MI) Mechanical Engineering Professor Ismat Abu-Isa, Xia Wang, Gary Barber and Elaine Petrach. According to U.S. Patent Application 20100021790, the bipolar plates are economical to produce and light weight.
The elastomeric highly conductive composite is an elastomeric matrix with conductive fillers for use as bipolar plates for a proton exchange membrane (PEM) fuel cell. The plates function to manage the flow of reactant gases through the fuel cells, and the elastomeric bipolar plates provide sealing to contain fuel cell reactant fluids and reaction by-products without the need for additional gaskets and low contact electrical resistance. Preferably, the elastomeric matrix is silicone rubber with silica filler with conductive filler selected from the group consisting of graphite fiber, natural graphite flakes, synthetic graphite flakes, graphite powder, and mixtures of the materials including high surface area conductive carbon black nanoparticles.
A new elastomeric composite material was investigated for bipolar plates for use in PEM fuel cells. To make the composite material, a two component silicone slurry was used as matrix with Cytec DKD fibers and synthetic flakes as conductive fillers. Low electrical resistivity was achieved at a filler concentration of 40% by volume or less. The synergy effect between graphite fibers and flakes was observed where lower resistivity was found for the composition consisting of a blend ratio of 28% and 7% for DKD graphite fiber and synthetic flakes.
Furthermore, both thermal conductivity and compression modulus were measured for the composite material developed in this research. The thermal conductivity of new material has a value of above 10 W/m-K, which meets the requirement set by DOE. Based on the measured compression modulus data, the strength of the silicone rubber based composite material could be reinforced before placed in a fuel cell to be used for a bipolar plate. This could be achieved by either adding a metal mesh or using a different matrix material.
FIG. 1A is a separated view showing detail of the bipolar plate in the fuel cell.
FIG. 13 is a schematic showing a three layer elastomeric composite bipolar plate.