Nanoparticulate catalysts infiltrated into SOFC (Solid Oxide FUel Cell) electrodes can significantly enhance the cell performance, but the stability of these electrodes has been an open issue. An infiltration procedure is reported that leads to a stable scandia-stablized zirconia (SSZ) cathode electrode performance.

The effective oxygen conductivities in the zirconia networks of porous LSM-YSZ and LSM-SYSZ composites [i.e. La0.85Sr0.15MnO3 (Y2O3)0.08(ZrO2)0.92 and La0.85Sr0.15MnO3-c2O3)0.1(Y2O3)0.01(ZrO2)0.89, respectively] were evaluated by an AC impedance technique using specimens in which LSM was removed by hydrochloric acid leaching. The oxygen conductivities of porous YSZ and SYSZ alone followed a Koh-Fortini relationship. LSM-containing zirconia network conductivities were additionally decreased by the presence of the LSM, presumably by increased grain boundary resistances. Constriction resistances were estimated to have a minor effect.

To improve the LSM-YSZ cathode performance of intermediate temperature solid oxide fuel cells (SOFCs), Sm0.6Sr0.4CoO3-sigma (SSC) perovskite nanoparticles are incorporated into the cathodes by a reaction-infiltration process. The SSC particles are ~;20 to 80nm in diameter, and intimately adhere to the pore walls of the preformed LSM-YSZ cathodes. The SSC particles dramatically enhance single-cell performance with a 97 percentH2+3 percentH2O fuel, between 600oC and 800oC. Consideration of a simplified TPB (triple phase boundary) reaction geometry indicates that the enhancement may be attributed to the high electrocatalytic activity of SSC for electrochemical reduction of oxygen in a region that can be located a small distance away from the strict triple phase boundaries. The implication of this work for developing high-performance electrodes is also d iscussed.