Lanthanum Gallate Electrolyte for Intermediate Temperature Sofc Operation

Abstract

Among the various oxygen conducting materials, Sr and Mg doped lanthanum gallate (LSGM) is attractive for use as an electrolyte in intermediate temperature Solid Oxide Fuel Cells (SOFC). the LSGM compositions show high oxygen conductivity as well as excellent stability over the range of oxygen partial pressures encountered in SOFC operation. Lowering the operating temperature is expected to provide a more expeditious route to commercial realization of Solid Oxide Fuel Cell (SOFC) based power systems. the intermediate operating temperature (600 to 800°C) allows the use of lower cost materials in both the stack and the balance of plant, and significantly slows down potential deleterious materials interaction, thus extending the useful long-term performance and thermal cycle capability. the primary challenge in long-term stability of LSGM-based fuel cell operation is the chemical reaction between the nickel anode and the LSGM electrolyte. A chemical modification to the anode was found to reduce the reaction. the modified anode composition is also shown to perform equivalent to standard NiO based anode. Single cells using thin (30 micron) electrolyte supported on a thicker anode were found to operate at a power density of greater than 500 mW/cm2 at 700°C. Stack test verification using thick electrolyte supported cells show promising performance. Stack tests using thin electrolytes are planned.