Screen printing of sol–gel-derived electrolytes for solid oxide fuel cell (SOFC) application

The idea of using the sol–gel technique for producing low-cost components for solid oxide fuel cell (SOFC) application has attracted great interest. Besides its economic advantages, the sol–gel technique additionally offers the chance to reduce either the thickness of the electrolyte and therefore to reduce ohmic resistances or to lower the sintering temperature of single components like the electrolyte layer, due to the clearly reduced particle sizes of colloidal distributed particles in the sol. The work presented here deals with the development of sols and their application in combination with yttria fully stabilized zirconia mixed-oxide powders for the preparation of screen-printing pastes. Besides physical, chemical and thermal characterization of the sols, variations of the composition of the sol as well as of the pastes composed of sol and mixed-oxide powder were evaluated for preparing dense, gas-tight layers sintered at various temperatures, resulting in sufficient gas-tightness to ensure high power density SOFCs. Additionally, technological screen-printing parameters were studied. Single cell tests (50 mm × 50 mm) revealed current densities of approx. 1 A/cm2. These values are comparable to current densities obtained by cells based on normal electrolyte layers, which were prepared in parallel.