Capillary-based water removal cathode for an air-breathing micro direct methanol fuel cell

摘要

This paper presents a capillary-based water removal cathode for an air-breathing micro direct methanol fuel cell (μDMFC). The mechanism of water removal from the cathode is studied and an array of capillaries with hydrophilic surface is designed on the ribs of the cathode structure. Microfabrication techniques, including double-side lithography and ICP, were used to fabricate the anode and cathode plates of the μDMFC on the same silicon wafer simultaneously. The surface of capillary structure was treated by low temperature oxygen plasma to improve the hydrophilicity. One μDMFC with capillary-based water removal cathode and another regular one without were both assembled and characterized. Measured results show that the μDMFC with water removal cathode achieves a power density of 2.35 mW/cm~2, 12% larger than that of the regular one with the value of 2.10 mW/cm~2. And the maximum current density of the novel μDMFC is 30 mA/cm~2, 20% larger than that of the regular one, 25 mA/cm~2. It is also clearly observed during the μDMFC operation that the water is drawn out from the capillary-based water removal cathode expectantly.