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Compositionally continuously graded cathode layers (CGCLs) of (Ba0.5Sr0.5)(Fe0.91Al0.09)O3−δ –Gd0.1Ce0.9O2 (BSFA–GDC) have been constructed by a handy and effective technique called wet powder spraying (WPS). CGCLs exhibit similar thermal expansion coefficient (TEC) value between adjacent thin layers. The continuously graded structure and the well-distributed components of BSFA–GDC cathode are confirmed by morphological characterization with scanning electron microscopy (SEM), and by compositional analysis with energy dispersion X-ray spectrometer (EDS), respectively. The polarization resistance (R p) of CGCLs with three different thicknesses is investigated by electrochemical impedance spectra (EIS). The EIS results show that CGCLs with a moderate thickness of 20 μm achieve the lowest R p of 0.301 Ω cm2 at 800 °C. In addition, anode-supported single cells with the configuration of NiO–YSZ/YSZ/GDC/BSFA–GDC have been fabricated and tested. The cell with the CGCLs thickness of 20 μm reaches the highest output power density of 848 mW cm−2 at 800 °C. [ABSTRACT FROM AUTHOR]

Abstract: A Sr2Fe1.5Mo0.5O6–Sm0.2Ce0.8O1.9 (SFMO–SDC) nanocomposite material has been prepared by the self-combustion method. The phase structure and morphology of the material have been characterized by means of X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). These results show the coexistence of perovskite and fluorite structures within the porous microstructure which are uniformly distributed throughout the prepared samples. The electrochemical performance of the material has been investigated by electrochemical impedance spectroscopy (EIS) measurements. Using an SDC interlayer SFMO–SDC composite cathode is prepared and applied onto a standard YSZ (8% Y2O3-stabilized ZrO2) electrolyte. A low polarization resistance of the prepared sample is obtained and remarkable performance of the SFMO–SDC based IT-SOFCs is achieved. It is demonstrated that the SFMO–SDC/SDC/YSZ/NiO–YSZ fuel cell reached power densities of 2.21, 1.66, 1.16 and 0.71 W cm−2 at 800, 750, 700 and 650 °C, respectively, in humidified H2 (3 vol% H2O). [Copyright &y& Elsevier]

Abstract: BaZr0.1Ce0.7Y0.1Yb0.1O3 (BZCYYb), a promising proton conductor of poor sinterability used in Solid Oxide Fuel Cells (SOFCs), has been densified in one hour at 850 °C by applying direct current sintering technique (DC-sintering). Under a constant electrical field, the current density through the specimen of BZCYYb rises rapidly when the temperature increases to a certain value. In DC-sintering process, we restrict the current density when the sharp increase occurs. By limiting current density to different values for one hour, we find that current density is the most important factor in DC-sintering process. The conductivity and the grain size of BZCYYb electrolyte increase significantly with the enhanced current density, while the different initial applied electrical fields have negligible effect. The stable stage of DC-sintering process can be explained by Joule heating. Corresponding real temperature of specimens is estimated by applying black body radiation theory. [Copyright &y& Elsevier]

Abstract: Nanoporous composite oxides Sr2Fe1.5Mo0.5O6–Sm0.2Ce0.8O1.9 (SFM–SDC) have been prepared by a facile one-step method as cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The SFM–SDC composite materials have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and electrochemical impedance spectroscopy (EIS). The EIS results exhibit that SFM–SDC40 (wt% 60:40) cathode has encouraging electrochemical performance with low polarization resistance (R p) on YSZ (Y2O3-stabilized ZrO2) electrolyte. Subsequently, bi-layer cathodes SDC/SFM–SDC are fabricated, and excellent electrochemical performance of such composite cathodes are observed. We demonstrate that the SDC interlayer significantly decreases the R p of cathode and accelerates the charge transfer process. As a result, the R p of the SDC/SFM–SDC40 bi-layer cathodes is almost 50% less than that of SFM–SDC40 cathode on YSZ electrolyte at 800 °C, and R p is only 0.11 Ω cm2. Compared with single cells without an interlayer, the anode-supported single cells with SDC interlayer exhibit enhancement in overall power performance. [Copyright &y& Elsevier]