Better membrane

Researchers at Duke University’s Pratt School of Engineering have developed a membrane that allows fuel cells to operate at low humidity and theoretically to operate at higher temperatures.

'The current gold standard membrane is a polymer that needs to be in a humid environment in order to function efficiently, said Dr Mark Wiesner, a Duke civil engineer. 'If the polymer membrane dries out, its efficiency drops. We developed a ceramic membrane made of iron nanoparticles that works at much lower humidities.'

Because the membrane is a ceramic, it should also tolerate higher temperatures, a property that Wiesner intends to demonstrate in future experiments.

'The efficiency of current membranes drops significantly at temperatures over 190 degrees Fahrenheit,'  explained Wiesner. 'However, the chemical reactions that create electricity are more efficient at high temperatures, so it would be a big improvement for fuel cell technology to make this advance.'

The membrane most commonly used today, known as Nafion, was discovered in the 1960s. As the temperature rises, the polymer becomes unstable and the membranes dehydrate, leading to a loss of performance.

In addition to its temperature and heat limitations, Nafion is also much more expensive to produce than the new membrane, Wiesner said, adding that membranes make up as much as 40 per cent of the overall cost of fuel cells.

Wiesner’s team also plans to study new ways of fabricating the new membrane to improve its durability and flexibility.