Perovskite-type Ba_0.5Sr_0.5Al_0.1Fe_0.9O_3-δ as Intermediate-Temperature Solid Oxide Fuel Cell Cathode

A cobalt-free perovskite-type Ba_0.5Sr_0.5Al_0.1Fe_0.9O_3-δ (BSAF) is developed and electro-chemically studied as solid oxide fuel cell (SOFC) cathode. The structures, electrical con-ductivity, and electrode polarizations in symmetrical cell based on mixed ion conducting electrolyte were investigated, respectively. The temperature dependence of conductivity of BSAF in air shows a typical semiconductor behavior with positive temperature coefficient up to 450 oC where the conductivity reaches 14.0 S/cm while above this temperature the negative temperature coefficient dominates the total conductivity. Electrochemical charac-terizations show desirable polarization resistance of BSAF cathode in a symmetric cell based on mixed ion conducting electrolyte at 650-700 oC. A single SOFC with BSAF cathode shows OCV of 1.0 V and maximum output of 420 mW/cm₂ at 700 oC with humidified hydrogen fuel and static air oxidant.