Thermal shock resistant composite cathode material Sm0.5Sr0.5CoO3–δ–La0.6Sr0.4FeO3–δ for solid oxide fuel cells

Abstract

The Sm 0.5 Sr 0.5 CoO 3-δ -La 0.6 Sr 0.4 FeO 3-δ 1:1 composite, obtained by sintering mixture of components, was tested as a prospective cathode material for the oxygen reduction reaction in solid oxide fuel cells. Catalytic activity of the prepared material was characterized using electrochemical impedance spectroscopy at 400, 450, 500, 550, 600, 650, and 700°C in oxygen and oxygen-argon mixtures in half-cells with Sm 0.2 Ce 0.8 O 1.9 as the electrolyte. Relatively low activation energies (65.2, 66.9, and 56.3 kJ mol −1 for P O2 /P = 1.0, 0.1, and 0.01, respectively) for the reaction polarization resistance were observed. The specific surface area and the pore distribution were measured by N 2 adsorption method. The non-localized density functional theory was used in the analysis of the porosity data. The activity of the prepared composite depended on the pore structure which, in turns, depends on the sintering temperature. The best results were obtained for the composite sintered at the temperature of 1000°C, where significant decrease in porosity is observed. The series of 53 thermal cycles, consisting of heating to 750°C and cooling to room temperature confirmed the stability of the composite.

Enhanced Performance of La0.8Sr0.2FeO3-δ-Gd0.2Ce0.8O2-δ Cathode for Solid Oxide Fuel Cells by Surface Modification with BaCO3 Nanoparticles

“…For example, the peak power densities at 750 • C were 712 and 993 mW/cm 2 for the bare and for the modified LSF-GDC, respectively, enhanced by 39.5% via the impregnation of BaCO 3 nanoparticles. This enhancement was significantly higher compared to the previous report on anode-supported cells based on LSF/LSF-GDC cathodes[22,25,33]. Figure7ddisplays the stability of NiO-YSZ-anode-supported SOFC with modified LSF-GDC cathode under a fixed voltage of 0.7 V. It was found that the measured current density of the single-cell was kept stable at ~700 mA/cm 2 , indicating excellent performance stability for about 100 h at 700 • C.…”

“…However, its performance is still inadequate compared to the requirements of cathode materials for IT-SOFCs. Consequently, several approaches have been proposed, to enhance the performance of LSF electrode materials for IT-SOFCs, such as developing composite cathodes, doping other metal ions, and surface modification [21][22][23].…”

Challenges and advancement in direct ammonia solid oxide fuel cells: a review

“…54 For example, to provide thermal compatibility between electrodes and electrolytes, composites such as cathodes made with Sm 0.5 Sr 0.5 CoO 3−δ (SSC) and ceria-based electrolytes have shown better thermal resistance than Sm 0.5 Sr 0.5 CoO 3−δ (SSC) to match compatibility with ceria electrolytes. 55 In addition, in ammonia-fueled solid oxide fuel cells, with state-of-the-art nickel-based electrodes, nitridation of the electrodes during thermal cycling occurs, which could result in severe performance degradation due to irreversible morphological changes in the anode microstructure and respective electrochemical properties. 36,56 The extent of nitrification depends upon the ammonia cracking reaction rate.…”