Influence of the synthesis method on the electrochemical properties of bilayer electrodes based on La2NiO4 + δ and LaNi0.6Fe0.4O3 − δ

Abstract

La2NiO4+δ (LNO) and LаNi0.6Fe0.4O3 (LNF) powders were synthesized using the two-step ceramic, glycine–nitrate combustion and modified Pechini method. The microstructure of the bilayer electrodes on their base was inspected using the original algorithm for scanning electron microscope (SEM) image processing. The electrochemical performance of the electrodes in contact with the Ce0.8Sm0.2O1.9 (SDC) electrolyte was studied with respect to the synthesis method, powder's dispersion and the sintering temperature of the electrode layers and their microstructural features. Irrespective of the powder's processing the increased sintering temperature of the functional layers (1300°C) was found to give better results in terms of adhesion and reduction in polarization resistance. Applying the LNF collector onto the LNO functional layer resulted in a sharp reduction in serial resistances due to a more uniform current distribution along the surface of the electrode. The lowest polarization resistance (ASR=0.18Ωcm2 at 700°C), which is among the best of those presented in the literature, was obtained for the bilayer electrode made of LNO and LNF powders produced by the glycine–nitrate combustion method.