Docomo Inc. and Fujitsu Laboratories Ltd. have developed a prototype direct-methanol fuel cell, utilising a nearly undiluted methanol solution. The two companies are jointly developing fuel cells for Docomo's mobile phones, and claim that their prototype cell has achieved a record average output of approximately 1 watt.

When higher concentrations of methanol are used, a phenomenon known as "methanol crossover" can occur due to fuel cells lacking an active mechanism to drive the flow of liquid. However, Fujitsu Labs claim to have overcome the problem by developing a solid, electrolyte film that reduces the methanol crossover effect by half compared to earlier films.

Docomo hopes to complete fuel cell development for use in an external recharger by March 2006 and finish a built-in fuel cell within two to three years, a Docomo spokeswoman said. "The performance of power generation has almost achieved our target. The next step is to minimize the system size so that we can build it into the fuel cell in a mobile phone," a Fujitsu spokesman said.