article
Citrate–hydrothermal synthesis, structure and electrochemical performance of La0.6Sr0.4Co0.2Fe0.8O3−δ cathodes for IT-SOFCs
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Autor
Garcia, Laurênia Martins Pereira
Macedo, Daniel Araújo de
Souza, Graziele L.
Motta, Fabiana Villela da
Paskocimas, Carlos Alberto
Nascimento, Rubens Maribondo do
Resumen
La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) powders were synthesized by a combination of citrate and hydrothermal methods. The thermal decomposition behavior of the as-prepared powder was carried out by simultaneous thermogravimetry–differential thermal analysis. The calcined powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and particle size distribution (PSD). Screen-printed LSCF/CGO/LSCF symmetrical cells were sintered between 1150 and 1200 °C and studied by impedance spectroscopy in order to assess the cathode kinetics for the oxygen reduction reaction. Rietveld refinement of XRD data showed the formation of a single perovskite LSCF phase with crystallite size of 53 nm at 900 °C. The best area specific resistance (ASR) value, measured in static air, was found to be 0.34 Ω cm2 at 750 °C, demonstrating that the novel citrate–hydrothermal method is an effective way to prepare cathode materials for SOFC. Cathode performance can be further enhanced by additional surface modification through impregnation with Pr-containing solution, reaching 0.17 Ω cm2 at 750 °C. Furthermore, the activation energy of the PrOx-impregnated cathode is 83.4 kJ/mol, i.e., much lower than 123.8 kJ/mol, the best value determined for PrOx-free cathodes