MIT, Sharp and Sony make big steps in advancing fuel cell technology

Posted by Wolfgang Gruener

Chicago (IL) – We have been hearing about fuel cells as the potential saviors of the PC industry’s 8-hour-notebook promise for quite some time, but the technology has yet to make a visible impact in products that are available to the consumer. In what appears to be a big month for fuel cells, Sharp, Sony and the Massachusetts Institute of Technology (MIT) reported independently from each other significant progress that could take fuel cell closer to production units.

The first to show a new prototype device was Sony, which unveiled its hybrid fuel cell technology earlier this month at the Small Fuel Cells 2008 conference in Atlanta. The device, which was known to be in development for some time, combines a direct methanol fuel cell (DMFC) as well as a Li-polymer battery as a backup power storage system.

The device is about 50 mm x 30 mm in size, which covers about one third of the area of an average business card, in size and small enough to be integrated at least in some consumer electronics devices. The peak power output is just 3 watts, which won’t get your notebook or even mobile Internet device anywhere, but cellphones are possible target devices for this technology. According to Sony, 10 ml of methanol would be enough to enable a device to display 14 hours of movie watching on a mobile device.

Sharp today announced earlier today at the 15th Fuel Cell Symposium in Tokyo that it has achieved the world’s highest density for DMFCs at 0.3 watt/cc – which is a 7x improvement over Sharp’s preceding fuel cell technology. The use of its technology will make it possible, according to the company, “to develop fuel cells that have almost the same volume but a longer continuous-use lifespan than lithium-ion batteries.” Sharp aims to sue this technology for devices such as PDAs, electronic dictionaries, and notebook computers.

What makes Sharp’s approach unique is a three-dimensional integrated stack structure through the use of thin cells produced through microfabrication. According to the company, this structure can be created by the alternate lamination of reed-shaped thin cells arranged in parallel at fixed intervals and reed-shaped (porous) spacers, with the cells and spacers running perpendicular to each other like a grid. With this structure, uniform and continuous spaces are created, making it possible to increase the cell surface area per unit volume and smoothly circulate the air, which is one of the sources for power generation.

Researchers from the MIT have discovered a way to increase the efficiency of fuel cells, which is a major roadblock in making the technology a viable alternative from traditional battery technologies. We were told that Paula Hammond, Avni Argun and Nathan Ashcraft were able to create an alternative material to Nafion, which is used as the electrolyte thatis sandwiched between the electrodes. Nafion is not only expensive, but it is permeable to methanol as well, allowing some of the fuel to seep across the center of the fuel cell – which ultimately decreases the efficiency of a fuel cell.  

The researchers used a technique known as layer-by-layer assembly to come up with an alternative thin-film material to Nafion: “We were able to tune the structure of [our] film a few nanometers at a time,” Hammond said. This thin film is claimed to be much less permeable to methanol but compares favorably to Nafion in proton conductivity. According to the researchers, a Nafion membrane coated with the new film increased the power output of a prototype fuel cell by more than 50%.

The team said is now exploring whether the new film could be used by itself, completely replacing Nafion. Apparently, they already have been successful in generating thin films with a consistency “much like plastic wrap” and the ability to stand alone.