Cobalt-free Composite Ba0.5Sr0.5Fe0.9Ni0.1O3–δ–Ce0.8Sm0.2O2–δ as Cathode for Intermediate-Temperature Solid Oxide Fuel Cell

Abstract

New cobalt-free composites consisting of Ba 0.5 Sr 0.5 Fe 0.9 Ni 0.1 O 3–δ (BSFN) and Ce 0.8 Sm 0.2 O 2–δ (SDC) were investigated as possible cathode materials for intermediate-temperature solid oxide fuel cell (IT-SOFC). BSFN, which was synthesized by auto ignition process, was chemically compatible with SDC up to 1100 °C as indicated by X-ray diffraction analysis. The electrical conductivity of BSFN reached the maximum value of 57 S·cm −1 at 450 °C. The thermal expansion coefficient (TEC) value of BSFN was 30.9×10 −6 K −1 , much higher than that of typical electrolytes. The electrochemical behavior of the composites was analyzed via electrochemical impedance spectroscopy with symmetrical cells BSFN-SDC/SDC/BSFN-SDC. The area specific interfacial polarization resistance (ASR) decreased with increasing SDC content of the composite. The area specific interfacial polarization resistance (ASR) at 700 °C is only 0.49, 0.34 and 0.31 Ω·cm 2 when 30, 40, and 50 wt% SDC was cooperated to BSFN, respectively. These results suggest that BSFN-SDC is a possible candidate for IT-SOFC cathode.