Composite cathode materials Ag-Ba0.5Sr0.5Co0.8Fe0.2O3for solid oxide fuel cells

Abstract

Silver-Ba0.5Sr0.5Co0.8Fe0.2O3-δ(BSCF) cathodes were prepared in two ways. In the first method, Ag-BSCF composite powder was prepared in ethanol solution, where Ag nanoparticles serving as a component in the preparation of Ag-BSCF composite cathodes had been previously obtained via one-step synthesis in absolute ethanol using a neutral polymer (polyvinylpyrrolidone). To the best of our knowledge, this is the first study to use a Ag sol obtained by the above method for preparation of Ag-BSCF composite powder. Then, a paste containing this powder was screen-printed on a Sm0.2Ce0.8O1.9electrolyte and sintered at 1,000 °C. In the second technique, an aqueous solution of AgNO3was added to a previously sintered BSCF cathode, which was then sintered again at 800 °C. The oxygen reduction reaction at the quasi-point BSCF cathode on the Sm0.2Ce0.8O1.9electrolyte was tested by electrochemical impedance spectroscopy at different oxygen concentrations in three electrode setup. The continuous decrease of polarization resistance was observed under polarization −0.5 V at 600 °C. The comparative studies of both obtained composite Ag-BSCF materials were performed in hydrogen-oxygen IT-SOFC involving samaria-doped ceria as an electrolyte and Ni-Gd0.2Ce0.8O1.9anode. In both cases, the addition of silver to the cathode caused an increase in current and power density compared with an IT-SOFC built with the same components but involving a monophase BSFC cathode material.