Researchers develop fuel cell that delivers record power per square centimetre

Solid oxide fuel cell efficiency has just taken a major step forward following research at the Nanoscale Prototyping Laboratory at Stanford University in the US.

An improved membrane and a lower operating temperature have created a device that is claimed to give the most power per square centimetre of any solid oxide cell so far developed.

These cells use hydrogen or natural gas and air to produce energy. The gases are separated from the oxygen by a solid oxide membrane that is covered in platinum particles to help create negatively charged oxygen ions. The oxide material pushes the ions through the membrane and into the fuel side where they react with the fuel to give off electrons that can then be harvested as electricity.

The goal for the researchers was to solve the problem of high operating temperatures (currently above 500°C) because ions move faster when they are hot. An external energy source can be supplied to kickstart the sequence but once the oxygen and fuel react they generate enough heat to feed back into the cell to maintain its operation.

It was realised early on by Prof Fritz Prinz, who headed up the research team, that what was needed was a more efficient membrane so that oxygen ions could be collected at cooler temperatures. They ascertained that the major problem was on the oxygen side of the membrane so a new design, some 60 nm thick and with bristles and bumps, was developed to increase its surface area.

It has taken more than 10 years to reach this point of development following a request by Honda in 1999 for better fuel cells. Now, by lowering the temperature to much less than 500°C, it is hoped to make available more materials that could be used in fuel cell design.