DETERMINATION OF THE METAL CONCENTRATIONS IN AN ANODE MATERIAL FOR SOLID-OXIDE FUEL CELLS

Ni-SDC is a very promising new anode material for SOFC systems. It exhibits a superb ionic and electronic conductivity at intermediate temperatures (400-700 degrees C) in comparison to Ni-YSZ. Ni-SDC is a composite material requiring careful microstructural and compositional tailoring during the preparation of the material. Ni-SDC was synthesized using a simplified Pechini method with a reaction between metal acetates and ethylene glycol, the latter serving as a chelating agent, and a reaction medium. The molar ratio between cerium and samarium in the ceramic part was 83 : 17 and the overall nickel content in the final product was set to 38 %. During the preparation of the material, several different intermediates were synthesized (i.e., a powdered product after the synthesis, an oxide mixture after the calcination and a mechanically ground powder after the milling), which may differ according to their chemical and morphological properties. In this respect, the material chemical composition expressed as concentrations of nickel, cerium and samarium was followed through the preparation sequence using various analytical techniques, i.e., the volumetric and gravimetric methods, ICP-OES, SEM-EDS and XRD. It appears that the obtained results diverge consistently with the analytical techniques used. Volumetry and gravimetry were used only for the nickel-content determination. Additionally, all the metals were simultaneously determined with ICP-OES and XRD Rietveld refinement in a bulk sample and with SEM-EDS for a point analysis. There is no unique answer as to which analytical method should be used at various preparation steps. Instead, suitable analytical methods or their combinations were chosen with respect to the analyzed material's appearance and its morphological and microstructural characteristics.