Scientists explain fuel cell structure

Ames, Iowa-- U.S. scientists said they've solved a fuel cell membrane structure problem using parallel cylindrical water nanochannels.

Although fuel cell cars are nearing commercial viability, scientists have been struggling to explain how a fuel cell's central component -- the proton exchange membrane -- works. Researchers at the U.S. Department of Energy's Ames Laboratory say they've solved the problem.

A fuel cell pumps hydrogen through the proton exchange membrane, which releases electrons in the form of electricity.

The model proposed by Ames scientists Klaus Schmidt-Rohr and Qiang Chen looked specifically at Nafion, a widely used perfluorinated polymer film.

"We know Nafion molecules have a rigid backbone structure with hair-like 'defects' along the chain," Schmidt-Rohr said. "But we didn't know just how these molecule were arranged. Our theory is these hydrophobic backbone structures cluster together to form long rigid cylinders about 2.5 nanometers in diameter with the hydrophilic 'hairs' to the inside of the water-filled tubes."

The scientists said the cylinders connect to create channels and it's that structure that helps explain how water and protons can so easily diffuse through Nafion.

The complex research is reported in the journal Nature Materials,

Copyright 2007 by United Press International.