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Toshiba matchbox-sized fuel cells suit mobile phones

Posted: 28 Jun 2004 ?? ?Print Version ?Bookmark and Share

Keywords:toshiba? direct methanol fuel cell? dmfc?

Toshiba Corp. has developed a matchbox-sized direct methanol fuel cell (DMFC) with no moving parts.

The prototype measures 22-by-56mm with a thickness of 4.5mm and includes a 2cc capacity fuel tank. The fuel cell weighs 8.5g, and has an output power of 100mW. Using a 99.5-percent concentration of methanol, the fuel cell can power low-power consumption devices such as MP3 audio players for about 20h, Toshiba said. Toshiba divides its DMFC development into two types, "active" and "passive." The new passive fuel cell aims for higher power - more than 10W at 10V to 20V generated by active systems, which use a pump and fan to feed methanol and oxygen into a cell stack where oxygen reacts with the methanol to produce electricity.

Toshiba unveiled an active prototype to power notePCs last spring, and plans to introduce a product later this year.

The passive model features a simpler structure, making use of the concentration gradient to feed methanol and oxygen to the cell stack. "We eliminated mechanical components such as a fan and fuel pump used in active-type DMFCs. Instead, we devised a way to supply fuel and air uniformly," said Fumio Ueno, a technology executive at Toshiba Display Device and Components Control Center.

Toshiba engineers reduced catalyst particles nanometer size. The electrodes measure 2-by-3cm, but deliver the same output power as Toshiba's conventional DMFC using electrodes five times larger.

Toshiba plans to introduce the small DMFC with an output power of about 100mW sometime next year.

Toshiba engineers said the fuel cell can power some portable devices such audio players. "We'll work on improving the output, then the fuel cell can power cellular phones," said Kazunori Fukuma, managing director of Toshiba Display Devices and Components Control Center.

For cellphone applications, Toshiba is targeting an output level of 2W at 4V. "More functions are implemented in a cellular phone, such as TV reception. This will increase the need for fuel cells," Fukuma said.

Initially, it will be difficult to replace current lithium ion batteries with DMFCs, and a hybrid configuration may make the most sense. The fuel cell could charge the lithium ion battery when the phone is idle.

- Yoshiko Hara

EE Times

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