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Abstract: The dependence of the degradation kinetics in Ni–CGO (cerium–gadolinium oxide) solid oxide fuel cell (SOFC) anodes upon salt evaporation is demonstrated operando with a custom built versatile reactor system. The system is based on evaporation and subsequent condensation of low concentration salt vapor aerosol mixtures representative of salt vapors typically present in biomass gasification processes. Fast changes in the charge transfer and ohmic resistance are observed in the anodes fuelled with a gas mixture containing a high KCl vapor concentration. Rapid condensation of salt vapors into the porous anode and partial delamination of the anode from the electrolyte surface because of salt deposits inside the porous anode is observed. The flexibility to produce vapor–aerosol mixtures with different concentrations and particle size distributions is proved, and suitability of these aerosols for anode testing in long term fuel cell test is evaluated. [ABSTRACT FROM AUTHOR]

In solid oxide fuel cells, doped strontium titinates have been widely studied as anode materials due to their high n-type conductivity. They are used as current conducting backbones as an alternative to nickel-cermets, which suffer degradation due to coking, sulphur poisoning, and low tolerance to redox cycling. In this work, anode backbone materials were synthesized from La0.2Sr0.25Ca0.45TiO3−δ (LSCTA-), modified with 5 wt.% Zn, and infiltrated with nickel (Ni)/ceria gadolinium-doped cerium oxide (CGO), Fe, and Co. The electrodes were further studied for their electrochemical performance using electrochemical impedance spectroscopy (EIS) at open circuit voltage (OCV) in different hydrogen to steam ratios and at various operating temperatures (850–650 °C). Infiltration of electrocatalysts significantly reduced the polarization resistance and among the studied infiltrates, at all operating temperatures, Ni-CGO showed excellent electrode performance. The polarization resistances in 3% and 50% H2O/H2 atmosphere were found to be 0.072 and 0.025 Ω cm2, respectively, at 850 °C, and 0.091 and 0.076 Ω cm2, respectively, at 750 °C, with Ni-CGO. These values are approximately three orders of magnitude smaller than the polarization resistance (25 Ω cm2) of back bone material measured at 750 °C. [ABSTRACT FROM AUTHOR]

Abstract: Two sets of solid oxide fuel cell (SOFC) electrode assemblies from different manufacturers were run under different operating conditions with different sulfur exposure, and then subjected to X-ray absorption spectroscopy (XAS) at the sulfur K (1s) edge. Within the detection limits of the spectrometer, pristine fuel electrodes (anodes) show no traces of sulfur. The anodes operated with sulfur-containing natural gas and H2S doped natural gas show spectra rich in sulfur structures. Two other electrodes run with sulfur-containing natural gas, one with a sulfur filter and the other without, show an XAS spectrum with a very broad peak, covering the entire sulfur absorption range, and thus not allowing for identification of specific sulfur signatures. These appear to be the first ever reported sulfur XAS data on SOFC anodes, and the XAS technique shows promise to resolve some hitherto unsolved issues on sulfur poisoning of SOFC, particularly regarding the molecular speciation of the sulfur components. [Copyright &y& Elsevier]

In this work, lanthanum calcium strontium titanates (La 0. 2 Sr 0. 25 Ca 0.45 TiO 3 ; LSCT A-) are modified with zinc, manganese and chromium (1%; 5%) for their application as solid oxide fuel cell anodes. These compositions are characterized by X-ray diffraction that indicate successful doping of metals onto the parent (LSCT A-) material without a change in the crystallography and leading to a lattice contraction depending on metal element and amount. Fabrication of the electrodes from the LSCT A- on yttria-stabilized zirconia plates is done by air spraying. The electrode performance of the materials is checked under reducing atmosphere (dry; 5% H 2 /Ar, humidified; 4% H 2 O/H 2) and at different sintering (1200 and 1250 ° C) and operating (750–650 ° C) temperatures. The materials sintered at high temperature (1250 ° C) show comparatively lower polarization resistances (R P) under humidified atmosphere, hence indicate better electrode performance in the presence of steam. Among these doped compositions, polarization resistance is found lower for LSCT A- modified with 1% Zn than all other doped compositions. Overall, the polarization resistance of both LSCT A- with 1% Zn (23 Ωcm2) and 5% Zn (25 Ωcm2) at 750°Cis found lower in comparison to the value reported at 900 ° C for parent material (45Ωcm2) under humidified atmosphere. [Display omitted] • Metals doped LSCT A- anode candidates, synthesis, and material characterizations. • Materials sintered at 1250 °C showed batter electrode performance than that sintered at 1200 °C. • Remarkably low Rp values of doped compositions than LSCT A- under reducing atmosphere and at 750 °C. • The lower value of activation energy confirmed LSCTZ a better anode candidate than others. [ABSTRACT FROM AUTHOR]