Synthesis and characterization of La0.595V0.005Sr0.4CoO3-delta as a novel cathode material for solid oxide fuel cells (SOFC)

The effect of vanadium doping on the crystal structure and on the electrical, electrochemical properties of La0.6-x V (x) Sr0.4CoO3-delta (x = 0.005-0.05) perovskite oxides performing as cathode materials in solid oxide fuel cells is investigated in this study. Crystal structure, surface morphology, and porosity of prepared cathode materials are characterized by X-ray diffraction, X-ray absorption fine structure, and scanning electron microscopy. For the first time, it has been proven by X-ray absorption fine structure that La3+ cation is replaced with V4+/5+ cation in perovskite structure. Since V4+/5+ cation has the radius almost half of the radius of La3+ cation, this replacement adds better properties to the perovskite structure such as ionic conductivity and catalytic activity for oxygen reduction reaction. The electrical conductivity at the intermediate temperatures (400-700 A degrees C) appears to be enough to yield a better performance in intermediate temperature-solid oxide fuel cells applications. The sample with 0.05% V4+/5+ doping exhibits its maximum electronic conductivity (sigma = 843 S.cm(-1) at 400 A degrees C) and minimum activation energy (Ea = 0.049 eV). The La0.595V0.005Sr0.4CoO3 material as electrode for symmetric cell configuration was prepared on both surfaces of yttria-stabilized zirconia substrates. Oxygen concentration related polarization experiment suggests that the oxygen adsorption-desorption process or reactions controlled by the atomic oxygen diffusion process followed by a charge transfer are the cathode reaction rate-limiting steps.