PNNL

Abstract

The polarization loss due to oxygen reduction at the cathode in solid oxide fuel cells is a thermally activated process; therefore, as temperature is lowered, the loss becomes substantial. Highly active cathodes have been investigated by several groups; equally important, if not more, is the stability of these electrodes. The high performance and stable Pr2NiO4 cathode was studied by impedance spectroscopy and dc current–potential sweeping methods. The power density in Pr2NiO4-based anode supported button cells was in the range between 0.65 and 0.7 W/cm2 at 750 degrees C at the external load of 0.8 V. The degradation rate at 0.8 V was approximately 3% per 1000 h up to 2000 h. The electrode resistance is a function of external loads, thus also varies with current densities. The relationship between electrode resistance and external loads is non-linear, which may changes in lattice oxygen nonstoichiometry of the cathodes.