Microstructure and electrochemical properties of porous La2NiO4+δ electrode screen-printed on Ce0.8Sm0.2O1.9 electrolyte
Superfine and uniform La2NiO4+δ powder was synthesized by a polyaminocarboxylate complex precursor method. La2NiO4+δ layers were screen-printed on dense Ce0.8Sm0.2O1.9 electrolyte substrates and sintered at 900–1,100 °C. The microstructure and electrochemical properties of the resulting porous electrodes were investigated with respect to sintering temperature. The results indicate a significant effect of sintering temperature on the microstructure and electrode polarization. It was found that elevating sintering temperature was favorable to the charge transfer process whereas undesired for the oxygen surface exchange process due to an increase of the grain size. Sintering at 900 °C was determined to be preferred in terms of the polarization resistance of the electrode. The porous electrode sintered at the temperature showed a fine-grained microstructure (about 200 nm) and a relatively low polarization resistance of 0.28 Ω cm2 at 800 °C. This work suggests that preparing the electrode from superfine starting powder is contributive to modifying the polarization properties.