Understanding Chemo-Mechanical Stability of Protonic Ceramic Cells Through Electronic Conduction in the BaCe_0.7Zr_0.1Y_0.1Yb_0.1O_3-δ Electrolyte

BaCe0.7Zr0.1Y0.1Yb0.1O3-δ (BCZYYb) is a promising ceramic electrolyte for reversible protonic ceramic cells. It is reported that BCZYYb-based cells show excellent long-term durability, particularly in the electrolysis mode, in contrast to the cells based on the conventional electrolyte yttria-stabilized zirconia. In this study, we investigate the chemo-mechanical stability behavior (a low tendency of delamination) of the BCZYYb-based protonic ceramic cells in terms of local electronic conduction in the electrolyte. The local electronic conductivity of the BCZYYb electrolyte is determined using Pt-probe-embedded cells near each electrode interface. The BCZYYb electrolyte exhibits sufficient p-type conductivity (∼10−3 S cm−1) near the oxygen electrode (corresponding p O 2 : 5.27–21 × 10−2 atm) and n-type conductivity (∼10−4 S cm−1) near the hydrogen electrode (corresponding p O 2 : 0.99–1.30 × 10−24 atm) at 600 °C. A standard cell is prepared and tested over long-term in the fuel cell (at positive and negative voltages) and electrolysis modes. The cell exhibits stable performance without delamination or cracks in both operating modes, owing to local electronic conduction.