Fabrication of anode supported SOFC using plasma-sprayed films of the apatite-type lanthanum silicate as an electrolyte

Apatite-type lanthanum silicates are promising electrolyte materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) because of the high oxide-ion conductivity and excellent transport properties. High sintering temperature in making thin and dense lanthanum silicate ceramics, however, is the most serious obstacle to the practical use of this material to SOFC electrolytes. In this study, we have succeeded in fabricating anode supported SOFC using plasma-sprayed Mg doped lanthanum silicate (MDLS) films as an electrolyte. The films were deposited on the NiO–MDLS substrates by atmospheric DC plasma spraying, followed by post heat treatments in a reduced atmosphere. During the heat treatments, the films were fully crystallized and the NiO–MDLS substrates reduced to the porous anodes of Ni–MDLS, which were confirmed by X-ray diffraction and scanning electron microscopy. The maximum power densities of the cell using (La0.6Sr0.4)(Co0.2Fe0.8)O3−δ cathode increased to 79.9, 45.4 and 21.6 mW cm− 2 at 800, 700 and 600 °C, respectively, compared to the Pt paste cathode, though the open circuit voltages of 0.90–0.97 V were similar for both cathodes.