Comparison of microchannel dimensions for air-breathing polymer exchange membrane microfuel cells

This paper evaluates proton exchange membrane (PEM) fuel cell microchannel width and depths ranging from 20 μm to 1000 μm. A DRIE process is employed to create the serpentine microflow field patterns from silicon wafers for channel width and depths ranging from 20 μm to 200 μm. To compare the smaller microchannel dimensions with conventional dimensions, computer numerical control (CNC) machining was used to create the 500 μm and 1000 μm flow field channel dimensions in delrin. All of the plates were coated with gold to prevent corrosion and to improve conductivity. Two air-breathing 2.54 cm × 2.54 cm × 1.47 cm fuel cell stacks were designed and assembled for this research. The same membrane electrode assembly (MEA) with an active area of 1 cm2 was tested with all of the silicon flow field plates with microchannels. The fuel cell performed well with the 20-μm width and depth flow channels (maximum power density of 65 W cm−2 or a maximum of 170 mA cm−2 at 0.2 V), although all of the I–V tests yielded good results for room temperature, air-breathing fuel cells. Microchannels with widths and depths from 100 μm to 20 μm look promising for new high-current density microelectro mechanical (MEMS) fuel cell designs.