Study on impedance spectra of La{sub}0.7Sr{sub}0.3MnO{sub}3 and Sm{sub}0.2Ce{sub}0.8O{sub}1.9-impregnated La{sub}0.7Sr{sub}0.3MnO{sub}3 cathode in single chamber fuel cell condition

摘要

Impedance spectroscopy was used to study the electrochemical performance of pure and ion-impregnated La{sub}0.7Sr{sub}0.3MnO{sub}3 (LSM) cathodes on YSZ (Y{sub}2O{sub}3-stabilized ZrO{sub}2) electrolytes in single chamber fuel cell conditions, i.e. a mixture gas with oxygen as oxidant, methane as fuel and nitrogen as dilute gas. Measurements were taken at the furnace temperature range of 550-750℃ and the CH{sub}4/O{sub}2 ratios from 1 to 2. Polarization resistances (R{sub}p) for pure and impregnated LSM cathodes increased obviously as the CH{sub}4/O{sub}2 ratio increased at 650-750℃ Polarization resistances of Sm{sub}0.2Ce{sub}0.8O{sub}1.9 (SDC) impregnated LSM cathode were much smaller than the ones of pure LSM cathode under the same conditions. Overtemperatures were occurred at both cathodes due to the partial oxidation of methane.