A New Family of Proton-Conducting Electrolytes for Reversible Solid Oxide Cells: BaHfxCe0.8-xY0.1Yb0.1O3-δ

Reversible solid oxide cells based on ceramic proton conductors have potential to be the most efficient system for large-scale energy storage. The performance and long-term durability of these systems, however, are often limited by the ionic conductivity or stability of the proton-conducting electrolyte. Here new family of solid oxide electrolytes, BaHfxCe0.8-xY0.1Yb0.1O3-delta(BHCYYb), which demonstrate a superior ionic conductivity to stability trade-off than the state-of-the-art proton conductors, BaZrxCe0.8-xY0.1Yb0.1O3-delta(BZCYYb), at similar Zr/Hf concentrations, as confirmed by thermogravimetric analysis, Raman, and X-ray diffraction analysis of samples over 500 h of testing are reported. The increase in performance is revealed through thermodynamic arguments and first-principle calculations. In addition, lab scale full cells are fabricated, demonstrating high peak power densities of 1.1, 1.4, and 1.6 W cm(-2)at 600, 650, and 700 degrees C, respectively. Round-trip efficiencies for steam electrolysis at 1 A cm(-2)are 78%, 72%, and 62% at 700, 650, and 600 degrees C, respectively. Finally, CO2-H2O electrolysis is carried out for over 700 h with no degradation.