Novel Anion-Doped Cathode Material SrFe1-x Si x O3-δF y for Intermediate-Temperature Solid Oxide Fuel Cells.

SrFe1-x Si x O3-δF y 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 SrFe1-x Si x O3-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 SrFe1-x Si x O3-δ. The electrochemical impedance spectroscopy results indicate that the oxygen transport capacity of the SrFe0.95Si0.05O3-δ material can be improved by doping with F-, but such a method can decrease the oxygen transport capacity of SrFe0.9Si0.1O3-δ. At 800 °C, the peak power density of the single cell supported by an anode and SrFe0.9Si0.1O3-δF0.1 as the cathode reached 388.91 mW/cm2. Thus, the incorporation of F- into SrFe1-x Si x O3-δ cathode materials can improve their electrochemical performance and enable their application as cathode materials for solid-oxide fuel cells.

Fe-based double perovskite with Zn doping for enhanced electrochemical performance as intermediate-temperature solid oxide fuel cell cathode material.

This study aims to investigate the implications of transition-metal Zn doping at the B-site on the crystal structure, average thermal expansion coefficient (TEC), electrocatalytic activity, and electrochemical performance of LaBaFe2O5+δ by preparing LaBaFe2-xZnxO5+δ (x = 0, 0.05, 0.1, 0.15, 0.2, LBFZx). The X-ray diffraction (XRD) results show that Zn2+ doping does not change the crystal structure, the unit cell volume increases, and the lattice expands. The X-ray photoelectron spectroscopy (XPS) and mineral titration results show that the oxygen vacancy concentration and Fe4+ content gradually increase with the increase in doping amount. TEC decreases with the increase in Zn2+ doping amount, and the TEC of LBFZ0.2 is 11.4 × 10-6 K-1 at 30-750 °C. The conductivity has the best value of 103 S cm-1 at the doping amount of x = 0.1. The scanning electron microscopy (SEM) images demonstrate that the electrolyte CGO(Gd0.1Ce0.9O1.95) becomes denser after high-temperature calcination, and the cathode material is well attached to the electrolyte. The electrochemical impedance analysis shows that Zn2+ doping at the B-site can reduce the (Rp) polarization resistance, and the Rp value of the symmetric cell with LaBaFe1.8Zn0.2O5+δ as cathode at 800 °C is 0.014 Ω cm2. The peak power density (PPD) value of the anode-supported single cell is 453 mW cm-2, which shows excellent electrochemical performance.