Topping off Your Fule Cell
“Why do you put water in your cell phone?”
“I am just topping off the feul cell”
Toshiba Announces World´s Smallest Direct Methanol Fuel Cell With Energy Output of 100 Milliwatts
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Tokyo — Toshiba Corporation, the world leader in fuel-cell technology for handheld electronic devices, today announced the prototype of a highly compact direct methanol fuel cell (DMFC) that can be integrated into devices as small as digital audio players and wireless headsets for mobile phone.
At a compact 22 x 56 x 4.5mm (maximum of 9.1mm, for the fuel tank), the slim prototype DMFC is as long and wide as a woman´s thumb, a size advantage that will give greater design freedom for developers of handheld electronic devices. The latest prototype, with its total weight only 8.5g, is small enough for integration into a wireless headset for mobile phones, but still efficient enough to power an MP3 music player for as long as 20 hours on a single 2cc charge of highly concentrated methanol. The new fuel cell outputs 100 milliwatts of power, and can continue to do so, non-stop, for as long as users top up its integrated fuel tank¡ªa process that is as simple as it is safe.
For the science-minded, read on…
* Active and Passive Fuel Supply System
Two types of DMFC are being brought to products: “active” and “passive”. Active systems use a pump and fan to feed methanol and oxygen into a cell stack, where the oxygen reacts with the methanol to produce electricity. Active systems are more complex and output more energy than passive systems, and are better suited for larger fuel cells. However, passive DMFC have a simpler structure that requires no pump or fan, and use the concentration gradient to deliver and circulate methanol and oxygen in the cell stack.
** Methanol Concentration
Methanol in a fuel cell delivers power most efficiently when mixed with water in a concentration of less than 10%¡ªa dilution requiring a fuel tank that is much too large for use with portable equipment. Toshiba overcame this and developed a system that allows a higher concentration of methanol to pass into the cell stack and produce electricity efficiently. As the result, Toshiba´s new DMFC realizes a fuel tank less than 1/10 the size of that required for storing the same volume of methanol in a concentration of less than 10%.
Basic Concept of DMFC
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