Sn-Dy-Cu Triply Doped BaZr0.1Ce0.7Y0.2O3-?: A Chemically Stable and Highly Proton-Conductive Electrolyte for Low-Temperature Solid Oxide Fuel Cells

BaCeO3-based proton conductors have comparatively high-proton conductivity, but the low chemical stability andhigh sintering temperature seriously hinder their practicalapplications in protonic ceramic fuel cells. Herein, we demonstratethat this limitation can be conciliated by using a triple-dopingstrategy in a BaZr0.1Ce0.7Y0.2O3-delta(BZCY) electrolyte, where thetriply doped BaCe0.7Sn0.1Dy0.15Cu0.05O3-delta(BCSDCu) exhibitsbetter chemical stability and conductivity and lower sinteringtemperature compared with the pristine BZCY. The phase-pureBCSDCu can be obtained at the sintering temperature of 1100 degrees Cprepared by solid-state reaction. The dense BCSDCu (>95%) isachieved at 1350 degrees C, which is significantly lower than the 1550 degrees Cof BZCY. The BCSDCu presents competitive proton conductivityof 13.6 mS cm-1under a moist H2atmosphere at 600 degrees C. The anode-supported single cell with the BCSDCu (approximate to 40 mu m) as theelectrolyte reaches the highest power density of 390 mW cm-2at 600 degrees C. On the basis of the distribution of relaxation time analysis,we not only distinguish the contribution of grain and grain-boundary conductivities but also identify the rate-determining step of thesingle-cell performance. The protonic conductivities, mechanical properties, and impurity clean parts induced by grain size effects arediscussed for the BCSDCu proton conductor