Electrochemical Characterisation of Ceramic SOFC Anodes

A simple method for the rapid electrochemical characterization of solid oxide fuel cell (SOFC) anodes is presented. Current-potential and impedance measurements have been performed at operating temperature in a simplified mariner using unsintered ceramic electrodes. Results for materials with different crystal structures and electrical properties are presented and show characteristic differences attributed to the materials' electrical properties. At 1000 degreesC in hydrogen saturated with water at room temperature materials with dominant electronic conduction show polarization resistances in the range 10-13 Omega cm(2). For mixed conducting ceramics as Y0.2Ti0.18Zr0.62O1.9+/-delta (YZT) and Ce0.6Gd0.4O2+/-delta the electrochemical performance is improved to 3.7 and 0.44 Omega cm(2), respectively. The best value measured for YZT was 0.7 Omega cm(2) when sintering the layer at 1300 degreesC. Initial evaluation of the impedance spectra indicates an extension of the reaction zone into the porous mixed conducting electrode, which can explain the higher electrochemical activity of the mixed conductors Ce0.6Gd0.4O1.8+/-delta and YZT. (C) 2001 The Electrochemical Society.