La1.98Ni04±δ, a new cathode material for solid oxide fuel cell: Impedance spectroscopy study and compatibility with gadolinia-doped ceria and yttria-stabilized zirconia electrolytes

Abstract A new SOFC cathode material, La 1.98 NiO 4± δ , was tested in presence of two electrolytes, yttria-stabilized zirconia (YSZ) and gadolinia-doped ceria (GDC). XRD analysis showed the absence of undesirable phases at the La 1.98 NiO 4± δ /GDC interface, whereas lanthanum zirconate (La 2 Zr 2 O 7 ), an insulating phase, is present between electrode La 1.98 NiO 4± δ and YSZ electrolyte. XPS analysis showed that the oxygen lattice can be present in form of La O and LaNiO 3 , which explains the high conductivity for these materials. At temperatures lower than 650 °C, the area specific resistance of the electrodes, measured by electrochemical impedance spectroscopy is significantly inferior when associated to GDC rather than YSZ electrolyte. In addition, in the case of GDC, a lower activation energy of about 0.7 eV was obtained, which could be explained by a higher mobility of oxide ions at the La 1.98 NiO 4± δ /GDC interface compared to the La 1.98 NiO 4± δ /YSZ one.