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

Abstract 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, BaZr 0.7 Pr 0.1 Y 0.2 O 3‐ δ (BZPY) shows improved sinterability as revealed by dilatometric measurements and scanning electron microscopy (SEM) analysis. Dense samples are obtained after sintering at 1500˚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˚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.