Synthesis and Characterization of CexSr1-xCr0.5Mn0.5O3-δ Perovskites as Anode Materials for Solid Oxide Fuel Cells (SOFC)

Abstract

CexSr1-xCr0.5Mn0.5O3 (CeSCM) compounds with x=0.25 and 0.5 have been prepared in argon. In comparison to the non-doped manganite Ce0.25Sr0.75MnO3, synthesized in air, chromium for manganese substitution improves the stability in wet hydrogen atmosphere, characteristic of an SOFC anode. In argon, the electrical conductivity at 900°C is 32.8 and 34.9Scm−1 for CeSCM 25 and CeSCM 50, respectively. In wet hydrogen, it is about 1Scm−1 at 900°C for CeSCM 25 and only 0.2Scm−1 for CeSCM 50. The rate of hydrogen oxidation reaction has been studied by using dense cone-shaped electrodes. Two main limiting steps are observed: the transfer of ionic species at the anode/YSZ interface at high frequency and hydrogen adsorption process at the surface of the electrode material at low frequency. In particular, the low electrical conductivity of CeSCM 50 seems detrimental for the performance.