Evaluation of yttrium-doped SrTiO3 as an anode for solid oxide fuel cells

Yttrium-doped SrTiO3 (SYT) was assessed as an anode material for solid oxide fuel cells in terms of electrical conductivity, phase stability, redox behavior, chemical compatibility with yttria-stabilized zirconia (YSZ) and La0.8Sr0.2Ga0.8Mg0.2O2.8 (LSGM), thermal expansion coefficient, and fuel cell performance. With the optimized composition Sr0.86Y0.08TiO3-delta, the electrical conductivity was as high as 82 S/cm at 800 degreesC and oxygen partial pressure of 10(-19) atm. A reversible change of conductivity was observed upon oxidation and reduction. The resistance to oxidation was enhanced by partially replacing Ti with transition metals such as cobalt. This material has high structural stability over a broad range of temperature (up to 1400 degreesC) and oxygen partial pressure (1-10(-20) atm). No phase change was found for mixtures of SYT with YSZ or LSGM sintered at 1400 degreesC for 10 h. The thermal expansion of doped-SrTiO3 was determined to be compatible with that of YSZ and LSGM. A maximum power density of 58 mW/cm(2) at 900 degreesC was obtained for single cells with the new anode. (C) 2002 Elsevier Science Ltd. All rights reserved.