A new approach for lowering the air-electrode interfacial resistance in medium-temperature solid oxide fuel cells is described. Thin interfacial layers of (Y2O3)0.25(Bi2O3)0,75(YSB) were interposed between Ag electrodes and (Y2O3)o.i(ZrO2)0.9(YSZ) electrolytes and their resistance rj measured in air using complex impedance analysis. The layers were deposited by magnetron sputtering. ri decreased as the YSB thickness fYSB increased, approaching the value for Ag on bulk YSB. For example, at 750°C ri decreased from —10 -Ωcm2 for Ag on YSZ to ~1.6 £2-cm2 for fYSB= 50 nm. Larger fYSB values yielded r1 ~ 1.5 £2-cm2, the same as the value for Ag on a YSB electrolyte. Auger electron spectroscopy measurements showed that the coverage of YSZ surfaces by YSB increased rapidly with increasing fYSB up to ≈50 nm; the thickness variation of r1- was thus readily explained by the variation of the YSB and YSZ surface areas. Initial results for (La0.7Sr03)CoO3 on YSZ with a 50 nm thick YSB layer yielded rx = 0.4 Ω-cm2 at 750°C.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry