Characterization of electrolyte–electrode interlayers in thin film solid oxide fuel cells

In order to reduce the operating temperature of solid oxide fuel cells (SOFCs), anode-supported cells incorporating thin film (∼10 μm) electrolytes in conjunction with anode/electrolyte and cathode/electrolyte interlayers were studied. SOFC button cells were prepared through deposition of colloidal slurries onto anode supported substrates and were analyzed as a function of temperature and polarization via voltammetry and electrochemical impedance spectroscopy (EIS). It was found that the electro-catalytic activity or electrode/electrolyte interfacial areas were enhanced through the addition of these interlayers. This performance improvement was attributed to the introduction of a diffuse mixed conduction region associated with these interlayers. The cathode is thought to benefit disproportionately from this enhancement. Single SOFC button cells with electrode interlayers were then characterized as a function of temperature and polarization to assess the involvement of these interfacial layers. EIS was applied and the data were used to deconvolute component impedances. Finally electrochemical models were developed to provide a more complete understanding of these assemblies under operation.