470971 Nanostructured Composite Intermediate-Temperature Solid Acid Fuel Cells Fabricated By Needleless Electrospinning
Due to the pure ionic conducting nature of the electrolyte, the electrochemical reactions occur at the so-called triple phase boundaries, between the catalyst, electrolyte and the gas phase. Because of the triple phase, decreasing just the size of the catalyst does not increase the electrochemical reaction rates. However, in case the size of the electrolyte is also decreased, the electrochemical reaction rate is higher at the triple phase boundary resulting in increased power density of the fuel cell .
Needleless electrospinning technique was employed to fabricate nanostructured SAFC electrodes from CDP/CsPO3-polymer solutions. Nanostructured CDP composite has the advantage of increased catalytic surface due to the large surface area. Needleless electrospinning is an inexpensive technique for producing nanostructured fuel cells at industrial scales. Instead of the commonly used nozzle, the needleless design employs a rotating drum immersed in a solution bath. Multiple Taylor cones form on the drum electrode surface resulting in rapid deposition of nanofibers over large areas. By applying CsPO3 solutions, the phosphate groups form a chain, increasing the viscosity of the solution. This enables electrospinning with negligible amounts of polymers. The fibers produced from the solutions have diameters between 30 nm – 300 nm depending on the initial solution concentration, substrate temperature, and applied voltage. The deposition area is over 100 cm2 and the deposition rate is up to 2 g/hr in the laboratory scale setup. Electrochemical characterization of the nano-composite electrodes, performed by A.C. impedance spectroscopy of symmetric cells under humidified hydrogen, confirmed the high activity of the electrospun nanocomposite electrodes. Fuel cell results using electrospun nanofibers from CsPO3 solutions demonstrate that a 0.86 V cell voltage can be obtained at a current density of 50 mA/cm2, which is ~10% higher than what can obtained using state-of-the-art techniques.
 C. R. Chisholm, D. A. Boysen, A. B. Papandrew, S. K. Zecevic, S. Cha, S., K. A. Sasaki, Á. Varga, K. P. Giapis, S. M. Haile, Interface, 2009, 18, 53-59.
 Y. Taninouchi, T. Uda, Y. Awakura, A. Ikeda, S.M. Haile J. Mater. Chem., 2007, 17, 3182.
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