Electrochemical Properties of Silver Based Composite Electrodes for SOFC Cathodes and Current Collectors

Performance of the cathode and cathode current collecting layers is of vital importance for development of stable solid oxide fuel cells (SOFCs) during long-term operational conditions. Although pure silver electrodes densify and become impermeable for gas transport at operating temperatures (e.g. 800oC) of SOFCs, incorporation of oxide particles introduces open porosity to silver composites. Previously, it was demonstrated that stable porosity and electrical properties of porous silver composites were achieved at 800oC in air for >5000 hours. Stable open porosity of obtained silver current collectors was utilized to fabricate LSM (lanthanum-strontium manganite), LSF (lanthanum-strontium ferrite), and LSCF (lanthanum-strontium-cobalt ferrite) composites of silver for SOFC cathode applications. Impedance spectroscopy techniques were applied to reveal polarization mechanisms of fabricated cathode/current collector layers. While infiltration of LSM gave rise to the performance of porous silver as cathode, infiltration of LSF and LSCF lowered the cathode polarizations further due to their enhanced ionic conductivities.