Enhancement of Electrochemical Properties, Impedance and Resistances of Micro-tubular IT-SOFCs with Novel Asymmetric Structure Based on BaZr0.1Ce0.7Y0.1Yb0.1O3-δ Proton Conducting Electrolyte

Anode-supported micro-tubular SOFCs based on a proton and oxide ion mixed conductor electrolyte, BaZr0.1Ce0.7Y0.1Yb0.1O3-delta (BZCYYb), have been successfully fabricated via phase-inversion process. Typical micro-tubular cell with the configuration of Ni-BZCYYb|BZCYYb|La0.6Sr0.4Co0.2Fe0.8O3-delta, consists of anode support, electrolyte and cathode with thicknesses of 200, 12, and 10 mu m, respectively. The cells show excellent electrochemical performance with the peak power densities of 1.040, 0.902, 0.721, and 0.590 W cm(-2) at 750, 700, 650, and 600 degrees C, respectively, with humidified (3 vol.% H2O) hydrogen as fuel and ambient air as oxidant. The AC impedance spectroscopy result shows low concentration polarization values of 0.016-0.021 omega cm(2) at 750-600 degrees C. Further, significant performance enhancement is observed during long-term stability test at 600 and 750 degrees C under constant voltage of 0.5 and 0.7 V over 120 h, respectively, indicating excellent stability of BZCYYb under fuel cell operating condition. The high performance is attributed to high-quality cell, validated by the dense, crack-free BZCYYb electrolyte film supported by the anode with micro sponge-like pores.