Development of 100w portable fuel cell system working with sodium borohydride

Erkan, Serdar
Fuel cells are electricity generators which convert chemical energy of hydrogen directly to electricity by means of electrochemical oxidation and reduction reactions. A single proton exchange membrane (PEM) fuel cell can only generate electricity with a potential between 0.5V and 1V. The useful potential can be achieved by stacking cells in series to form a PEM fuel cell stack. There is a potential to utilize 100W class fuel cells. Fuelling is the major problem of the portable fuel cells. The aim of this thesis is to design and manufacture a PEM fuel cell stack which can be used for portable applications. The PEM fuel cell stack is planned to be incorporated to a NaBH4 hydrolysis reactor for H2 supply. Within the scope of this thesis a new coating technique called “ultrasonic spray coating technique” is developed for membrane electrode assembly (MEA) manufacturing. New metal and graphite bipolar plates are designed and manufactured by CNC technique. A fuel cell controller hardware is developed for fuel supply and system control. The power densities reached with the new method are 0.53, 0.74, 0.77, and 0.88 W/cm2 for 20%, 40%, 50%, 70% Pt/C catalyst by keeping 0.4mg Pt/cm2 platinum loading constant, respectively. The power density increase is 267% compared to “spraying of catalyst ink with air pressure atomizing spray gun”. All parts of the PEM fuel cell stack designed were produced, assembled, and tested. The current density reached is 12.9A at 12 V stack potential and the corresponding electrical power of the stack is 155W.