Development and Characterization of Component Layers for proton-conducting High Temperature Solid Oxide Cells

Abstract

In the present study, component layers of anode supported Solid Oxide Cells (SOCs) with proton-conducting electrolyte are prepared with wet-chemical methods. Nickel oxide-yttriumstabilized zirconate (NiO-YSZ) and Nickel oxide-yttrium-doped barium cerate zirconate (NiO-BCY) substrates are prepared by tape-casting. Anode functional layers with same compositions are screen-printed on the surface of substrates. Yttrium-doped barium cerate– zirconate (BCZY) layers are fabricated through co-sintering and wet chemical method with solid-state reaction. The size of obtained samples is about 5 cm·5 cm. Differential air leak test, Scanning electron microscope (SEM), X-ray diffraction (XRD) are performed to investigate gas-tightness, microstructure- and compositions of samples BCZY layers prepared by co-sintering are not densified to gas tight even at temperature up to 1560 °C, because the sinterbility of BCZY is poor. As the samples are sintered at high temperature, bending and cracking occur because of the mismatch with dilatomeric properties and thermal expansion coefficient of different layers. With wet chemical method, YSZ thin film with thickness of about 1 µm is prepared and then densified. Confirmed by SEM and XRD, barium diffuses into YSZ and transforms it into yttrium-doped barium zirconate (BZY) phase at high temperature. BaCO3 and BCZY are applied as barium source. BaCO3 may damage samples with its high reactivity. By adjusting Ba source, temperature, duration, the transformation of YSZ into BZY can be improved. LCSF-BCZY is applied as air electrode. I-V and power density curves and electrochemical impedance spectroscopy (EIS) present poor performance of the cell. The remaining YSZ film contributes to the suppression of the operation of the cell.