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New Fuel Cell Material From MIT Said To Increase Power Output By 50%

May 19, 2008 by Jeff Shepard

MIT is claiming that its engineers have improved the power output of one type of fuel cell by more than 50% through technology that could help the devices find a much broader market, particularly in portable electronics. The new material key to the work is said to be considerably less expensive than its conventional industrial counterpart, among other advantages.

"Our goal is to replace traditional fuel–cell membranes with these cost–effective, highly tunable and better–performing materials," said Paula T. Hammond, Bayer Professor of Chemical Engineering and leader of the research team. She noted that the new material also has potential for use in other electrochemical systems such as batteries.

The MIT team focused on direct methanol fuel cells (DMFCs), in which the methanol is directly used as the fuel and reforming of alcohol down to hydrogen is not required. Such a fuel cell is attractive because the only waste products are water and carbon dioxide (the latter produced in small quantities). Also, because methanol is a liquid, it is easier to store and transport than hydrogen gas, and is safer (it won’t explode). Methanol also has a high energy densit – a little goes a long way, making it especially interesting for portable devices.

Using a relatively new technique known as layer-by-layer assembly, the MIT researchers created an alternative to Nafion. "We were able to tune the structure of film a few nanometers at a time," Hammond said, getting around some of the problems associated with other approaches. The result is a thin film that is two orders of magnitude less permeable to methanol but compares favorably to Nafion in proton conductivity. To test their creation, the engineers coated a Nafion membrane with the new film and incorporated the whole into a direct methanol fuel cell. The result was an increase in power output of more than 50%.

The team is now exploring whether the new film could be used by itself, completely replacing Nafion. To that end, they have been generating thin films that stand alone, with a consistency much like plastic wrap. This work was supported by the DuPont-MIT Alliance through 2007. It is currently supported by the National Science Foundation.

In addition, Hammond and colleagues have begun exploring the new material’s potential use in photovoltaics. That work is funded by the MIT Energy Initiative. This Institute–wide initiative includes research, education, campus energy management and outreach activities, an interdisciplinary approach that covers all areas of energy supply and demand, security and environmental impact.