The company said in a statement that the phone was co-developed by Toshiba and the fuel cell was developed with Hitachi. It described the power system as a hybrid in which power is supplied both by a fuel cell and a methanol fuel tank on the back of the device and by a more traditional lithium-ion battery. The fuel cell can be replenished from a small cartridge, the company said.
KDDI said that the system provides 2.5 times as much battery capacity as regular batteries alone. In a statement, the operator called the system, "a fuel-cell handset of the near future," although it did not say when the device would be available for sale.
It did say, however, that the phone is "about the same size" as the same phone without the fuel cell system. The two phones it plans to demonstrate at the trade show weigh between 150 grams and 160 grams, the company said.