Solid oxide fuel cells with (La,Sr)(Ga,Mg)O3 electrolytes and Sr(Ti0.3Fe0.7)O3 anodes and cathodes yield a power density of 0.6 W/cm2 at 0.7 V at 800°C in air and humidified hydrogen. The polarization resistance values are 0.085 Ω· cm2 for the cathodes and 0.13 Ω· cm2 for the anodes. The cell current-voltage characteristics and the anode resistance dependence on hydrogen partial pressure (pH2) both indicate that adsorption limits the hydrogen oxidation process.Amodel is developedwhere dissociative hydrogen adsorption becomes an increasingly important rate-limiting step, relative to charge transfer, as temperature and pH2 decrease. The model fits the data well for cell voltages >0.5 V, deviations at lower voltages are tentatively explained by an increase in anode oxygen content. The model also fits the electrochemical characteristics of cells with (La,Sr)(Cr,Fe)O3 anodes and previously-reported data on other oxide anodes.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry