The Fuel Cell Development Information Center (FCDIC) held a seminar titled "Dawn of the age of fuel cell for mobile devices" on August 30, 2006. The lecturers were invited from leading companies involved in fuel cell development such as NTT DoCoMo, Inc., NEC Corp., Toshiba Corp., Hitachi, Ltd. and Canon Inc.
First, NTT DoCoMo talked about the following four requirements of the fuel cell for use in mobile phones: (1) power at generation point; (2) orientation-free property; (3) improvements in safety and maintenance; and (4) other issues.
NTT DoCoMo co-developed a fuel cell that can be used as an exterior recharger with Aquafairy Co. in July 2006 in a bid to commercialize it as early as in 2007. In the lecture, the company mentioned not just the basic performance as a power source for mobile devices but also specific requirements with respect to reliability and safety in actual usage.
In regard to the power at generation point listed as (1) above, the company estimates that approx. 3-5 W (5.4 V) and 1-2 W (3.6 V) are required to recharge and directly drive a handset, respectively. In addition, pulse-driving is essential in order to follow the transient responses of power.
As for the orientation-free property listed as (2), since the orientation of a mobile phone is not fixed according to the usage situations, the liquid level of fuel and the direction in which gasses at the fuel and air electrodes are exhausted may vary. Thus, in order to maintain the properties in current and voltage, the company suggests that a DC-DC converter, capacitor and the like be provided to adjust the varied amounts.
Regarding improvements in safety and maintenance mentioned as (3), NTT DoCoMo reports that it is considering setting up safety standards to maintain the safety of users exceeding 40,000,000 at present. For example, the company insists that a heat test should be conducted at 150°C to simulate a situation where a handset has generated abnormal heat, thereby checking for explosion, fire, smoke, etc. As for maintenance, the company claims that it is required to develop a technique to detect the property degradation, along with a simple method to confirm the remaining capacity of fuel cell.
With regard to other issues listed as (4), the company stressed the necessity to address compatibility issues on, for example, the concentration of methanol and the method to supply fuel, which presently differs depending on the manufacturer.
To prepare for the future, NTT DoCoMo is determined to develop an external recharger with higher performance than that of such rechargers as the company currently sells. Meanwhile, the company aims to develop a built-in fuel cell with a volume, current capacity and output of 10-20 mL, 1 Ah or more and 1 W or more, respectively.