The world’s smallest Direct Methanol Fuel Cell (DMFC), capable of delivering a 100 mW, (claimed to be five times the output of any previous DMFC) has been developed by Toshiba .
The fuel cell weighs 8.5 g and measures 22 by 56 by 4.5 mm, which means that it is capable of being integrated into portable devices such as digital audio players and wireless headsets for mobiles. Toshiba says the cell could potentially power an MP3 music player for as long as 20 hours on a single 2 cm3 charge of highly concentrated methanol.
The DMFC adopts a “passive” fuel supply system that feeds methanol directly into the cell. This helps to avoid the potential problem of “methanol crossover” in which methanol and oxygen combine without an energy-producing reaction. Toshiba claims to have optimised the structure of the fuel cell’s electrodes and polymer electrolyte membrane that trigger the energy producing reaction.
This approach allows the use of a highly concentrated methanol solution as a fuel, which also overcomes a major obstacle to small fuel cells: reducing the size of the fuel tank. By using concentrated methanol the company says it has been able to reduce its DMFC fuel tank size to less than one tenth compared to what would otherwise be required if the conventional approach of methanol diluted with water was used.
Toshiba expects to commercialise DMFCs for PCs later this year, and for smaller handheld devices in 2005.