Sharp Boosts Power Density of Compact Fuel Cell

By Susumu Tajima
Tech On
May 16, 2008

Sharp Corp announced that it developed a compact fuel cell with an extremely high power density for use in mobile devices.

The power density per unit volume of the new fuel cell is much higher than that of the existing products. By further developing this technology, it will be possible to produce a fuel cell that can be continuously operated for a longer period of time with a volume comparable to that of the existing Li-ion rechargeable batteries, Sharp said.

The details of the new fuel cell were unveiled at the 15th Fuel Cell Symposium May 15, 2008.

It is a passive-type direct methanol fuel cell (DMFC) that does not use a pump, etc. Current passive DMFCs have a simple structure and can be downsized. But, at the same time, they have a problem of low power density. This time, Sharp drastically improved the power density with the adoption of its proprietary cell called “three-dimensional highly integrated stack structure,” which is arranged in the heart of the fuel cell.

The latest fuel cell is composed of power generation and fuel units that have volumes of approximately 8 and 10cc (18cc in total), respectively. And it weights about 18g. The average power is approximately 2W, and the electric energy is 7.4Wh, according to the company.

These properties are substantially equivalent to those of the Li-ion rechargeable battery used in the company’s electronic dictionaries. The fuel cell is superior in both power and energy densities because the Li-ion rechargeable battery has a volume of about 22cc and weighs about 47g.

Through the use of microfabrication based on the MEMS technology, Sharp increased the cell’s surface area per unit volume and provided a structure that can easily circulate air.

The company unveiled related technology at MEMS 2008, an academic meeting on MEMS, in January 2008 in the US.

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