Characterization of YSZ-YST Composites for SOFC Anodes

Porous composites of Sr0.88Y0.08TiO3-δ (YST) and yttria-stabilized zirconia (YSZ) were formed by tape-casting methods and examined as potential anodes for SOFC. Even after calcination to 1773 K, the YSZ and YST crystallites remain as separate phases, as demonstrated by XRD and SEM with EDX analysis. Furthermore, it was possible to fabricate anode-supported electrolytes by calcination of a bilayer tape formed by casting a thin YSZ tape over the green, YSZ-YST tape. Cells with anodes having 50-wt% YST and 80-wt% YST were tested and shown to yield good open-circuit voltages, although the power densities in H2 and CH4 between 973 and 1173 K were modest. Impedance spectra of the cells suggest that the conductivity of the YST-YSZ composites is insufficient for high performance.