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, BaZr_0.7Pr_0.1Y _0.2O_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. Pr and Y co-doped barium zirconate (BZPY) is a chemically stable electrolyte with high proton conductivity. The good sinterability of the BZPY electrolyte allows the development of an anode-supported solid oxide fuel cell (SOFC) based on a thin BZPY proton conducting membrane. The performed fuel-cell tests confirm that BZPY is a promising electrolyte material for intermediate-temperature SOFC applications.