Optimization of the Lanthanum Tungstate/Pr2NiO4 Half Cell for Application in Proton Conducting Solid Oxide Fuel Cells

La6WO12, recently reformulated La28xW4+xO54+3x/2 exhibits a good level of protonic conductivity and chemical stability toward acidic gases. It is therefore a potential material for use as electrolyte in proton conducting solid oxide fuel cells (PC-SOFC). Pr2NiO4 is a cathode material tested for SOFC in which proton conductivity has been demonstrated recently. In this study, compatibility between lanthanum tungstate and praseodymium nickelate has been investigated by powder X-ray diffraction (XRD). Microstructure of symmetrical cells based on the lanthanum tungstate and Pr2NiO4 has been analyzed by scanning electron microscopy (SEM) and performance of the cathode has been evaluated by electrochemical impedance spectroscopy (EIS) through the value of the area specific resistance (ASR). To optimize the ASR value, different parameters were modified such as the Pr2NiO4 calcination temperature, the firing temperature of the symmetrical cells, the thickness of the Pr2NiO4 layer, and the composition of the composite cathode. An ASR value of 0.46cm2 at 700 degrees C has been obtained showing that lanthanum tungstate electrolyte associated with Pr2NiO4 cathode is a promising half cell for application in PC-SOFC.