Gallium Doped Sr(CoFe)O3 Perovskite as the Stable Electrodes of the Flexible SOFC and SOEC for Both Power Generation and Hydrogen Production

Thursday, 27 July 2017
Grand Ballroom East (The Diplomat Beach Resort)
M. Xie, X. Meng, N. Yang, Y. Shen, B. Meng (Shandong University of Technology), S. Liu (Curtin University, Australia), and X. Tan (Tianjin Polytechnic University)
Cobalt and ion based perovskite such as Sr(CoFe)O3, Ba0.5Sr0.5Co0.8Fe0.2O3-δ and La0.6Sr0.4Co0.2Fe0.8O3-δare considered as promising cathodes of SOFC or anodes of SOEC. However, cobalt and iron oxides are easily reacted with the gases such as H2, CH4, CO2and water steam at high temperature, causing the perovskite structure to be easily decomposed. To stabilize the perovskite structure of the electrodes is a serious challenge for the fabrication of the long-life SOFC or SOEC.

In this work, gallium is used as a dopant to stabilize Sr(CoFe)O3, developing a SrCo0.8Fe0.1Ga0.1O3-δ(SCFG) perovskite material to work as the electrodes of flexible SOFC and SOEC with a microtubular structure.

SCFG show a high oxygen reducing performance when it is prepared into oxygen separation membrane, Obtaining an oxygen flux of 3~6 mL·min-1·cm-2 at the temperature of 800~950°C. Even under pure CO2, pure CH4 and H2(4vol%), SCFG membrane still works steadily for as long as 200 h with no decreasing.

A microtubular solid oxide cell in the configuration of Ni-YSZ|YSZ|GDC|SCFG is fabricated and tested in SOFC or SOEC modes from 550 to 850°C, using hydrogen as the fuel or as the product, respectively. Under SOFC mode, a maximum power density of 1044 mW cm-2 is obtained at 750°C. In the electrolysis mode, when the applied voltage is controlled at 2V, the electrolysis current density reaches 3.33A cm-2 at 850°C with the hydrogen production rate up to 22.9 mL min-1 cm-2 (STP). These results reveal that SCFG is a very promising oxygen electrode material for the application in both SOFC and SOEC.