Novel Anion-Doped Cathode Material SrFe_1- Si O_3-δF for Intermediate-Temperature Solid Oxide Fuel Cells

SrFe_1- Si O_3-δF cathode materials (x = 0.05, 0.1, 0.15; y = 0, 0.1, 0.5) were prepared via a solid-state method. X-ray diffraction results show that the synthesized F doping samples were perovskite structure. X-ray photoelectron spectroscopy findings show that F^- anions were doped into SrFe_1- Si O_3-δ. Transmission electron microscopy and energy-dispersive spectroscopy were performed to analyze the microstructure and element distribution in the materials, respectively. Double-layer composite cathode symmetric cells were prepared through a screen printing method. Scanning electron microscopy images revealed that the double-layer composite cathode adhered well to the electrolyte. The doping with F^- can increase the coefficient of thermal expansion of SrFe_1- Si O_3-δ. The electrochemical impedance spectroscopy results indicate that the oxygen transport capacity of the SrFe_0.95Si_0.05O_3-δ material can be improved by doping with F^-, but such a method can decrease the oxygen transport capacity of SrFe_0.9Si_0.1O_3-δ. At 800 °C, the peak power density of the single cell supported by an anode and SrFe_0.9Si_0.1O_3-δF_0.1 as the cathode reached 388.91 mW/cm². Thus, the incorporation of F^- into SrFe_1- Si O_3-δ cathode materials can improve their electrochemical performance and enable their application as cathode materials for solid-oxide fuel cells.