Porous Gd-doped ceria barrier layer on solid oxide fuel cell with Sm0.5Sr0.5CoO3−δ Cathodes

Abstract

Cobaltite based perovskites, such as Sm0.5Sr0.5CoO3-δ (SSC), are attractive as a cathode for solid oxide fuel cell (SOFC) due to their high electrochemical activity and electrical conductivity. In this study, nano-sized SSC powders were synthesized by a complex method. To prevent reactions between cathode and an yttria-stabilized zirconia (YSZ) electrolyte, we propose a Gd-doped ceria (GDC) porous barrier layer and formed barrier layers, screen-printed to 5, 10, and 15μm thicknesses. The performance of SOFCs without a GDC layer decrease by 23% from 0.78Wcm−2 to 0.6Wcm−2 after 12h of operation at 780°C. A SOFC with a screen-printed GDC of 5μm shows a performance decrease of only 4% from 0.75Wcm−2 to 0.72Wcm−2 after 12h of operation at 780°C. Fuel cell performance decreases with decreasing thickness of the porous GDC layer, which may result from the lowered SSC active area due to its reaction with the YSZ electrolyte. The increase in ohmic resistance due to a thicker porous GDC layer is mitigated by a decrease in ohmic resistance due to reduced reaction between the SSC and YSZ. To use SSC in SOFCs, a barrier layer should be applied to obtain grater fuel cell performance and stability.