Redox Stability of SrNb[sub x]Ti[sub 1−x]O[sub 3]–YSZ for Use in SOFC Anodes

The conductive properties of bulk (SNT) and porous –yttria-stabilized zirconia (YSZ) composites for , 0.05, and 0.20 have been examined under relevant solid oxide fuel cell (SOFC) operating temperatures and redox cycling conditions. The porous composite conductivities were approximately 1 order of magnitude lower than the corresponding bulk material. In order to obtain reasonable conductivity levels for SOFCs, samples were prereduced at in . The conductivity of prereduced samples increased with increasing Nb content when directly measured in humidified ; however, when considering the conductivities measured after redox cycling, there appears to be no benefit to using higher dopant levels. After redox cycling at , a composite conductivity of at in humidified (3% ) was achieved for and 0.05 and a composite conductivity of was achieved for . Fuel cell power densities of at and at were achieved in humidified (3% ) with a porous SNT–YSZ anode infiltrated with Pd and , a thick YSZ electrolyte, and an (LSF), LSF–YSZ cathode. The implications of these results for the development of redox-stable anodes are discussed.