Raphaël Ihringer

Anode supported solid oxide fuel cells with screen-printed cathodes

To increase power density at reduced temperature operation of SOFC, thin film 8YSZ electrolytes were deposited on Ni–YSZ anode support plates by tape casting and cofiring. Cathode behaviour, limiting cell output at lower temperature, was studied in more detail. Cathodes were deposited by screenprinting and firing. With consecutive layers of doped lanthanum manganite and cobaltite, power density of 0.5 W cm−2 at 750°C was obtained using hydrogen fuel. On cells of 100 cm2, no fuel diffusion limitation above 70% conversion occurred, and electrical efficiency of 35% was achieved. Actual cell temperature increases significantly above a current density of 0.3 A cm−2. This effect causes erroneous electrode and cell characteristics.

Co-casting and co-sintering of porous MgO support plates with thin dense perovskite layers of LaSrFeCoO3

A tape casting co-sintering route is described in which thin dense layers of LaSrFeCoO3 (LSFC) have been formed on planar, porous MgO substrates 100- 200 micron thick. SEM analysis of the sintered structure showed that it was possible to eliminate most of the residual porosity in the LSFC layer, but maintain a porosity between 25 and 45% in the MgO support layer. The LSFC layer dit not reveal many cracks. The overall shrinkage of the co-sintered structure was about 25%. The LSFC layer topography was smooth and uniform with a metallic-like lustre. A good correlation was obtained between the observed microstructure and the gas permeability measurements made at room temperature.

Materials for Methane-fueled SOFC Systems

Abstract: A short overview of recent work on electroceramic materials relevant to methane-fueled SOFC systems is given. Various fuel feed options are considered, such as pure methane, biogas, and the addition of reforming agents. The principle and implementation into SOFC systems of mixed conducting ceramics for oxygen separation is described, as well as their characterisation by electrochemical methods. Ceramic anodes capable of operating with methane-rich fuel injection are presented. The document concludes with electrochemical results on planar anode supported ceramic fuel cells operating at reduced temperature.