Improving the cathodic performance of La0.7Sr1.3CoO4 by substituting Ni in Co sites for intermediate solid oxide fuel cells application

In this study, the effect of Ni substitution in Co sites of La _0.7Sr _1.3CoO ₄ Ruddlesden-Popper oxides was investigated, as cathode for using in solid oxide fuel cells. Structural and lattice dynamic analyses revealed that La _0.7Sr _1.3Co _1−xNi _xO ₄ (x = 0, 0.1, 0.3 and 0.5) had tetragonal structure and the lattice volume decreased as a results of Co ³⁺ stabilization in low spin state with substituting Ni ions in Co sites. In addition, the x-ray photo electron spectroscopy (XPS) indicated that Co ⁴⁺/Co ³⁺ ratio decreases in these synthesized powders with enhancement of Ni dopant, while the oxygen vacancy and the oxygen adsorption in the samples increased. The electrochemical performance of La _0.7Sr _1.3Co _1−xNi _xO ₄ synthesized powders was studied using electrochemical impedance analysis of the symmetrical cells. The electrochemical processes were determined by employing distribution of relaxation time (DRT) analysis. It was revealed that doping of La _0.7Sr _1.3CoO ₄ with Ni leads to decreasing the polarization area specific resistance from 1.2 Ω cm ² for x = 0 to 0.36 Ω cm ² for x = 0.5 at 800 °C. So, it can be concluded that by Ni substitution in Co sites the cathodic performance of La _0.7Sr _1.3CoO ₄ improves significantly and these compounds can be considered as suitable cathode candidates to be used in IT-SOFC.