Cermet cathodes for strontium and magnesium-doped LaGaO3-based solid oxide fuel cells

To check the suitability of La0.9Sr0.1Ga0.85Mg0.15O3−δ-Ag cermets as cathode material for solid oxide fuel cell (SOFC) with Sr- and Mg-doped LaGaO3 electrolyte a series of cermets with different Ag contents were prepared by conventional sintering process. The chemical compatibility between La0.9Sr0.1Ga0.85Mg0.15O3−δ (LSGM) and Ag was investigated by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. Thermal expansion coefficient of the cermets was measured as a function of Ag content and was found to increase with increasing metallic content. Oxygen adsorption at the surface of the cermets could be detected but no reaction or solid solubility between LSGM and Ag was found. It was noticed that a minimum of 30 wt.% Ag is needed to form a cermet with percolating network. From impedance spectroscopy measurement activation energy for the polarization conductance was found to be around 110 kJ mol−1.