La_(1.98)NiO_(4±δ), a new cathode material for solid oxide fuel cell: Impedance spectroscopy study and compatibility with gadolinia-doped ceria and yttria-stabilized zirconia electrolytes

摘要

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_2Zr_2O_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℃, 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.