Bismuth oxide-coated (La,Sr)MnO₃ cathodes for intermediate temperature solid oxide fuel cells with yttria-stabilized zirconia electrolytes

Taking Y₂O₃ stabilized Bi₂O₃ (YSB) as an example, bismuth oxide-added (La,Sr)MnO₃ (LSM) is evaluated as a cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs) with 8 mol% Y₂O₃ stabilized ZrO₂ (YSZ) electrolytes. YSB was added to LSM cathodes using an impregnation method, dramatically improving the electrode performance. The interfacial polarization resistance R_p, at 700 °C for the electrode coated with 50 wt.% of YSB is 0.14 Ω cm², 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_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_p than that of parallel-fabricated LSM electrodes with samaria-doped-CeO₂ 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.