Methanol fuel cell

Toshiba has 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 phones.

At 22 x 56 x 4.5 mm with a maximum of 9.1 mm for the fuel tank, the prototype is small enough for integration into a wireless headset for mobile phones, but still efficient enough to power an MP3 music player for up to 20 hours on a single 2 cc charge of highly concentrated methanol.

The cell has an 100 output of 100 mW and can maintain this as long as users top up its integrated fuel tank.

The DMFC adopts a 'passive' fuel supply system which feeds methanol directly into the cell. In developing a passive DMFC, Toshiba found an answer to the potential problem of 'methanol crossover', in which methanol and oxygen combine without an energy-producing reaction.

The company has optimised the structure of the cell's electrodes and polymer electrolyte membrane that trigger the reaction. This allows the use of a highly concentrated methanol solution as a fuel, which also overcomes a major obstacle to small fuel cells: achieving a very small fuel tank.