Synthesis and properties of Ba0.5Sr0.5(Co0.6Zr0.2)Fe0.2O3-δ perovskite cathode material for intermediate temperature solid-oxide fuel cells

A highly stable perovskite cathode material, Ba0.5Sr0.5(Co0.6Zr0.2)Fe0.2O3-δ (BSCZF) for intermediate temperature solid-oxide fuel cells (IT-SOFCs) was synthesized via the improved EDTA-citric acid complexing technique combined with high-temperature sintering. The product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical impedance spectra (EIS) measurements. An electrolyte-supported BSCZF/SDC/Ni-SDC fuel cell was fabricated to evaluate the performance of the material. The XRD study indicates that the sintering temperature higher than 950 deg. C is sufficient to the formation of clean single BSCZF perovskite phase. Due to the incorporation of Zr ions, BSCZF perovskite exhibit lower electrical conductivity with higher activation energy but higher structural stability than the Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) parent oxide. The maximum electrical conductivity of BSCZF attains 16.9 S cm-1 at around 540 deg. C. Impedance spectra showed that the ASRs of BSCZF cathode on samaria doped ceria (Ce0.8Sm0.2O1.9, SDC) electrolyte are low but are still slightly larger than those of BSCF at similar conditions. The BSCZF/SDC/Ni-SDC cell exhibited a stable output with the maximum power densities of 30, 75, 139 and 241 mW cm-2 at 550, 600, 650 and 700 deg. C, respectively. Due to the high electrochemical performances as well as the excellent stability, BSCZF perovskite may be an attractive cathode material for IT-SOFCs.