A single fuel cell does not produce enough to produce enough energy to power a car, so fuel cells are stacked, with a bipolar plate between each cell through which electrons are conducted. The hydrogen fuel and oxygen, which are part of the fuel cell chemistry, enter the plate through channels along the face on each side. Creating these channels in the bipolar plate is a manufacturing challenge.

So much of a challenge in fact that about 29 percent of the cost of a fuel cell stack is the bipolar plate, and machining channels into the plates is a significant factor, says Donald Baird, who is the Harry C. Wyatt Professor of Chemical Engineering at Virginia Tech. “Machining one millimeter by one millimeter (1 mm x 1 mm) channels is expensive and time-consuming.”

So scientists in chemical engineering are developing compression moldable composite bipolar plates with channels included.

Using a thermoplastic composite and a wet-lay process (like making paper), the researchers created a material with high electrical conductivity and good mechanical properties, that is a barrier to hydrogen and oxygen, and that is easy to manufacture. The properties of the bipolar plates exceed the Department of Energy’s (DOE) minimum standards and industry requirements in terms of strength and of electrical conductivity along the plate – although through-plane conductivity needs some improvement, Baird says.

The Virginia Tech researchers are continuing to work on optimizing the manufacturing scheme – how fast the channels can be created and the material can be cooled, Baird says. “We are also working on different methods of heating, such as induction versus microwaving.”

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