The device, manufactured by Fujitsu Laboratories, generates power by combining methanol and hydrogen. DoCoMo claims that development of the cell could be completed by the end of 2005.
"The micro fuel cell is aimed at meeting user demands for more convenient handsets with greater power capacity, as well as reduced environmental impact," DoCoMo said in a statement.
DoCoMo added that it is keen to boost the power available to cell phone users, as applications such as video streaming have considerable power demands.
The micro fuel cell is shaped like a cradle that holds the handset for a recharge. It weighs about 7 ounces and generates almost 3.8 watts of power. Each methanol cartridge provides only enough power for one recharge, so people would either have to carry a number of cartridges about or hope they could find a store selling one, if necessary.
Fujitsu announced at the start of this year that it had found a way of using highly concentrated methanol to create fuel cells with up to 10 times as much power per unit weight as a conventional lithium-ion battery.
By developing a better membrane, Fujitsu can use a concentration of 30 percent methanol in its fuel cells, compared withthat use concentrations of between 10 percent and 25 percent.
The real challenge facing NTT DoCoMo and Fujitsu, and every other company working on fuel cells, is to convert their prototypes into commercial products. For many years, the technology industry has been told that fuel cells are just around the corner, and that's where they still are today.
Graeme Wearden of ZDNet UK reported from London.