Investigation of LSM 1.1–ScSZ composite cathodes for anode-supported solid oxide fuel cells

Abstract

La 0.8Sr 0.2Mn 1.1O 3 (LSM 1.1)–10 mol% Sc 2O 3-stabilized ZrO 2 co-doped with CeO 2 (ScSZ) composite cathodes were investigated for anode-supported solid oxide fuel cells (SOFCs) with thin 8 mol% Y 2O 3-stabilized ZrO 2 (YSZ) electrolyte. X-ray diffraction (XRD) results indicated that the ScSZ electrolytes displayed good chemical compatibility with the nonstoichiometric LSM 1.1 against co-firing at 1300 °C. Increasing the CeO 2 content in the ScSZ electrolytes dramatically suppressed the electrode polarization resistance, which may be related to the improved surface oxygen exchange or the enlarged active area of cathode. The 5Ce10ScZr was the best electrolyte for the composite cathodes, which caused a small ohmic resistance decrease and the reduced polarization resistance and brought about the highest cell performance. The cell performances at lower temperatures seemed to rely on the electrode polarization resistance more seriously than the ohmic resistance. Compared with the cell impedance at higher temperatures, the higher the 5Ce10ScZr proportion in the composite cathodes, the smaller the increment of the charge transfer resistance at lower temperatures. The anode-supported SOFC with the LSM 1.1–5Ce10ScZr (60 : 40) composite cathode achieved the maximum power densities of 0.82 W/cm 2 at 650 °C and 2.24 W/cm 2 at 800 °C, respectively.