New La2Ni1-xO4±δ (0.01≤x≤0.1) Materials as Cathode for Solid Oxide Fuel Cells

In order to improve the electrochemical performances of solid oxide fuel cells (SOFC), La2Ni1-xO4 +/-delta (0.01 <= x <= 0.1) materials were prepared by citrate route and then used as cathodes for oxygen reduction reaction (ORR). Their microstructure and morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The excess of the oxygen contents and the electrical conductivities were performed by iodometric titration and 4-point probs method respectively. The electrochemical performances were subsequently studied by impedance spectroscopy and the results obtained are promising which confirm the good electrochemical performance of most of the analyzed compositions. It has been shown that, the electrical conductivity increases with increasing of the excess oxygen content. The morphology of such cathode materials has a significant influence on the electrochemical behavior of the studied electrode materials. Accordingly, among the studied materials, the Ni-10% deficient material (symbolised by LN10O) shows the best electrochemical properties with respect to oxygen reduction reaction. Such sample is the most porous one, conducing to an easy diffusion of oxygen and, consequently, favouring the ORR phenomenon.