ABSTRACT
Portable devices for telecommunications with technical advances and userfriendly functions call upon an energy source greater than the limit of conventional technology. Because mobile devices perform more functions of conversation and exchanging information via the Internet and have digital mobile broadcasting (DMB) systems, cameras, etc., the requirements of more power and energy are getting increased. Mobile devices require nearly 3800 mAh per day, which needs three 5-h charges with a conventional power source for a 1-day use. Direct methanol fuel cells (DMFCs) have been becoming attractive as an alternative to Li-ion batteries in portable electronics for higher power and energy. Also, there is a demand for lighter and longeroperation power sources for mobile informative devices. Of all the system characteristics of DMFCs, energy efciency, energy density, power density, and cost have to be competitive with rechargeable batteries. The requirements for the portable DMFC suggested by DOE are the following [1]:
• Power density, 100 W∙l-1
• Energy density, 1000 Wh∙l-1
• Lifetime, 5000 h • Cost, $3 W-1
CONTENTS
12.1 Introduction ................................................................................................335 12.2 Roles and Requirements of PEM ............................................................. 337 12.3 Technical Approaches ...............................................................................342
