Development of a mini power unit (MPU) based on portable air-breathing PEFC Stack

Polymer electrolyte fuel cells (PEFC) were developed as an alternative power source for stationary and mobile application due to their high power density and low operating temperature. Their future acceptance, especially for transportation application depends on the ability to develop systems which are competitive in cost and performance to the conventional power supply (Internal Combustion Engines and batteries). Furthermore, recent advances in PEFC technology urged the interest of electronic companies to the application in portable devices. In order to replace batteries pack with a PEFC power system, this last must be simple, light and relatively low-cost. “Airbreathing ” stack is an emerging class of fuel cells for all those low power devices actually served by conventional batteries, because it does not require sub-systems for air supply and humidification In this work the development of a mini power unit (MPU) based on portable air-breathing PEFC stack is reported. The stack is composed by 10 cells with an active surface of 25 cm2, and designed to produce a rated power of 15 W operating between 5 and 7 Volts, with a total current load in the range 2-4 A. Hydrogen is supplied in end off configuration at a pressure of 0.2 barg, the MEA platinum load was maintained at 2.0 mg cm-2 and a Nafion 112 membrane was used. The mini power unit based on the this stack can supply power at 9.5 V stabilised output.