Effect of Ag Addition on the Structural Properties of Ba0.5Sr0.5Co0.8Fe0.2O3-δ–Sm0.2Ce0.8O1.9 Composite Cathode Powder

Abstract

Barium strontium cobalt ferrite (BSCF) materials are effective cathode materials for solid-oxide fuel cells (SOFCs) because of their high conductivity and excellent catalytic activity for oxygen reduction and mobility. The ionic conductivity of this type of composite cathode can be improved by adding some catalyst materials to help enhance their electrode activity toward oxygen reduction reaction. A catalyst material speeds up the reaction of the composite cathode and thus increases the oxygen-exchange rate and ionic-diffusion rate. This study aimed to investigate the effects of adding Ag as a catalyst material to Ba0.5Sr0.5Co0.8Fe0.2O3-δ–Sm0.2Ce0.8O1.9 (BSCF-SDC) composite cathode powders. The powders were mixed by high-energy ball milling at 550 rpm. After mixing and calcining at 950 °C for 2 hours, Ag was dry milled with the calcined BSCF-SDC composite cathode powder at five different weight percentages (1wt%–5wt%). The powders were characterized by various analytical methods. X-ray diffraction (XRD) was used for phase and structure identification. A Zetasizer Nano ZS was used to determine particle size. The Archimedes principle and field-emission scanning electron microscopy (FESEM) were used to examine density porosity and morphology, respectively. XRD results demonstrated that the BSCF-SDC-Ag peak increased with increased Ag amount. Zetasizer results revealed that the powder particles expanded in size, consistent with the FESEM images. Furthermore, the porosity ranged within sufficient values (20%–40%) needed for SOFC cathodes. All these findings indicated the effectiveness of the BSCF-SDC powders as SOFC cathode materials.