Determining the Maximum Power Output of Active and Passive Direct Methanol Fuel Cells

Determining the Maximum Energy Output of Active and Passive Direct Methanol Fuel Cells

Sean O'Connell

            Interest in fuel cell technology has rapidly advanced over the last decade, as increased concern over dwindling fuel resources and climate change have prompted an increase in the development in renewable energy sources. Direct Methanol Fuel Cells (DMFCs) have tremendous potential to replace power sources for common electronics, including lithium-ion batteries found in cellphones. This research explored the different factors that affected the voltage and current density outputs of active and passive DMFCs.

            The main component of the DMFC used in the research was the Gas Diffusion Layer (GDL), which consisted of a nafion layer between two carbon woven cloths. One carbon cloth was coated with a platinum catalyst and acted as the cathode, the other acted as an anode with a platinum-ruthenium catalyst. The GDL was placed between an anode and cathode plate to complete the Membrane Electrode Assembly (MEA). The passive DMFC, which relied on ambient air to supply oxygen to the cathode, completed the assembly with a polymethyl cell held together by screws and gaskets. The active DMFC required air to be cycled through the assembly, so inlet and outlet airlines were added to the assembly.

Many variables were altered and explored in an attempt to achieve the highest possible voltage and current output of the cell. Since nafion had been shown to increase conductivity in the cell, another factor tested was the amount of nafion used in the GDL, specifically if adding an additional coating of nafion to the anode would increase the conductivity of the cell. The concentration of the methanol solution was also altered to see the effects on the output of the cell. In the active cell, the airspeed was sped up and slowed to see how the change in airflow would affect the cell. Results of this study show that the highest voltage output of the cell occurred when a passive cell with 0.5M methanol solution and no additional nafion was tested, while the highest current density output occurred when the concentration and nafion levels were the same, and the aiflow was 448 mL/min. The passive cell was tested on a 0.3V portable fan, which it was able to successfully power.

This research shows the immense potential and possible applications of DMFCs. DMFCs have a higher theoretical power density than lithium-ion batteries, create less harmful emissions in their creation and operation, and are a renewable energy source. With more research and development, DMFCs could develop into a significant replacement to common batteries and other power sources.