Bismuth oxide-coated (La,Sr)MnO{sub}3 cathodes for intermediate temperature solid oxide fuel cells with yttria-stabilized zirconia electrolytes

摘要

Taking Y{sub}2O{sub}3 stabilized Bi{sub}2O{sub}3 (YSB) as an example, bismuth oxide-added (La,Sr)MnO{sub}3 (LSM) is evaluated as a cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs) with 8 mol% Y{sub}2O{sub}3 stabilized ZrO{sub}2 (YSZ) electrolytes. YSB was added to LSM cathodes using an impregnation method, dramatically improving the electrode performance. The interfacial polarization resistance R{sub}p, at 700℃ for the electrode coated with 50 wt.% of YSB is 0.14 Ωcm{sup}2, which is only 0.2% of the value for a pure LSM electrode. The high oxygen ionic conductivity and the catalytic activity of YSB, as well as the favorable electrode microstructure are likely reasons for the dramatic reduction of R{sub}p. The YSB-added LSM cathodes also exhibited lower overpotential and higher exchange current density than the pure LSM cathode. Moreover, these electrodes show much lower R{sub}p than that of parallel-fabricated LSM electrodes with samaria-doped-CeO{sub}2 as well as other LSM-based electrodes reported in the literature, demonstrating the superiority of the of YSB as the ionic conduction component in composite LSM electrodes. The superior performance of the single cell further demonstrates that the bismuth oxide-added LSM cathode is an excellent candidate for IT-SOFCs.