Chemically Stable Pr and Y Co-Doped Barium Zirconate Electrolytes with High Proton Conductivity for Intermediate-Temperature Solid Oxide Fuel Cells

A chemically stable and highly proton-conductive electrolyte is developed by partially substituting the Zr site of Y-doped barium zirconate (BZY) with 10 mol% of Pr. Compared to BZY, BaZr0.7Pr0.1Y0.2O3-delta (BZPY) shows improved sinterability as revealed by dilatometric measurements and scanning electron microscopy (SEM) analysis. Dense samples are obtained after sintering at 1500 degrees C for 8 h. Moreover, BZPY shows good chemical stability in the wide range of fuel-cell operating conditions. The larger density and the enhanced grain growth, compared to BZY, allow the volume content of grain boundaries, which generally show a high resistance for proton transport, to be reduced and, thus, a high proton conductivity can be achieved in the temperature range of interest for practical applications (above 10(-2) Scm(-1) at 600 degrees C). The good sinterability, chemical stability, and high conductivity of the BZPY electrolyte enabled the fabrication of single-cell prototypes based on a thin BZPY membrane by a simple and cost-saving co-pressing method. Electrochemical impedance spectroscopy (EIS) analysis performed during fuel-cell tests under open-circuit conditions confirms the good electrical performance of BZPY as electrolyte material. To improve the present fuel-cell performance adapted cathode materials for this BZPY electrolyte need to be developed.