Tailoring the chemical stability of Ba(Ce0.8-xZrx)Y0.2O3-δ protonic conductors for Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFCs)

A soft chemistry method was used to synthesize BaCe0.8-xZrxY0.2O3-delta (BCZY, with 0.0 <= x <= 0.8) proton conductors to combine the high proton conductivity of barium cerate and good chemical stability of barium zirconate. To verify the chemical stability, all the synthesized oxides were exposed to 100% CO2 at 900 degrees C for 3 h and the phase composition of the resulting specimens was investigated by X-ray diffraction (XRD) analysis. The chemical stability against CO2 increased with increasing the Zr content, with good results for samples with x >= 0.5. The electrical conductivity of the samples was investigated as a function of the Zr content using Electrochemical Impedance Spectroscopy (EIS) measurements. Hydrogen-air fuel cell experiments were carried out at 700 degrees C using the BCZY proton conducting electrolytes and platinum electrodes. Promising performance was observed for BaCe0.3Zr0.5Y0.2O3-delta because it maintains the good chemical stability of barium zirconate but with improved electrical conductivity and fuel cell performance. (C) 2008 Elsevier B.V. All rights reserved.