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  • The Electrochemical Society  (2)
  • 1
    Online Resource
    Online Resource
    Measurements of Gas Shielding Factors for Cu, Fe, Ni
    The Electrochemical Society ; 2015
    In:  ECS Meeting Abstracts Vol. MA2015-01, No. 13 ( 2015-04-29), p. 1119-1119
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2015-01, No. 13 ( 2015-04-29), p. 1119-1119
    Abstract: Knowledge of the vaporization behavior of different metals in dependence of temperature, pressure of the ambient atmosphere as well as its purity, is a crucial issue for high temperature materials. It has even been proven in the literature that the amount of mass loss of a sample due to vaporization strongly depends on the purity of the atmosphere in which the sample is heated. This coincides with the value of partial pressures of specific impurities. The so called gas shielding factor describes the ratio of the evaporation rate in a specific gas atmosphere and the evaporation rate under UHV. The dependence of the gas shielding factor on the pressure and the purity of the process gas is remarkable. The range can extend over several orders of magnitude [1]. Within the framework of the presented work, vaporization experiments using a HT- Thermobalance with UHV supply have been carried out for the elements Fe, Cu, and Ni under inert gas atmosphere and with defined oxygen partial pressures. Thereby, the oxygen partial pressure has been maintained using an oxygen ion pump. Here, an electric current between +10 and -10 mA is applied to an yttrium-doped zirconia tube operated at a temperature of 600 °C. The current flow results in oxygen being transferred into or out of the ambient gas provided to the experimental set-up with a flow rate of about 2 cm 3 /min. The ion pump yields accuracy in oxygen flow of 10 -9 l/min and, therefore, enabled precise adjustment of pO 2 within the area of interest. The gas shielding factor not only depends on the gas purity but also on the investigated material itself. The dependency from the oxygen partial pressure for example is influenced by the partial vapor pressure of the corresponding oxides and their dissociation pressure. Reference [1] E. Fromm, METALLURGICAL TRANSACTIONS A, VOLUME 9A , DECEMBER 1978, 1835-1838
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2015-01/13/1119
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2015
    detail.hit.zdb_id: 2438749-6
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  • 2
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    Online Resource
    Forschungszentrum Jülich – Current Activities in SOC Development
    The Electrochemical Society ; 2021
    In:  ECS Meeting Abstracts Vol. MA2021-03, No. 1 ( 2021-07-23), p. 196-196
    Details
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2021-03, No. 1 ( 2021-07-23), p. 196-196
    Abstract: Understanding degradation mechanisms in SOCs remains an ongoing issue for its mitigation and to reach levels that will bring the technology closer to commercialization. Benefiting from our experience in performing long-term tests on stacks (up to 100,000 h) post-test examination of the components of several of these stacks gave a better understanding about various degradation effects. Among others the chromium poisoning of La 0.58 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) and La 0.6 Sr 0.4 CoO 3-δ (LSC) air electrodes used over the past decade in the cells will be presented. In parallel alternative air electrode materials for low-temperature application based on La 2 Ni 1-x Co x O 4+δ (LNCO) are being developed and the influence of A- and B-site substitution on the structural, physico-chemical and electrochemical properties of the materials is investigated. First promising results of a short-stack with Ni/YSZ substrate cells with La 2 Ni 0.8 Co 0.2 O 4+δ air electrodes will be presented. Based on the earlier experience obtained from the operation of a 5 kW (in FC-mode) reversible system (rSOC), stacks and supporting components were adapted to scale-up to a 10/40 kW (FC/EL)-class system. This included among others the development of a scalable steam generator of which a prototype was tested separately. This allows for the optimization of the efficiency of the system, especially in electrolysis mode. The 10/40 kW class rSOC system will contain four 20-layer sub-stacks in the planar-type window frame stack-design, each with four standard-sized cells (10 × 10 cm²) in a 2 × 2 array per layer. Our activities focus more and more on investigating high-temperature electrolysis as a first step in future Power-to-X value chains using renewable energies, focusing on CO 2 -valorization through co-electrolysis of H 2 O and CO 2 for syngas production as well as pure CO 2 -electrolysis. The performance and stability of cells and short-stacks were investigated with DC and AC techniques for various feed gas compositions. Especially the analysis of the Electrochemical Impedance Spectroscopy (EIS) measurements performed on State-of-the-Art cells in the boundary region between pure CO 2 -electrolysis and co-electrolysis with low steam content in the feed gas led to a better insight in the role of the reverse water gas shift reaction (RWGS) in the conversion of CO 2 under these conditions. For the (co-)electrolysis case a model of the multi-physics phenomena occurring on cell level was developed using the COMSOL platform. The model is fully coupled including electrochemical, chemical, heat and transport phenomena occurring at single cell level. On stack level a steady-state, 3-D, non-isothermal, and homogenized model for rSOC stacks has been developed from an extension of previous studies and implemented into the open-source library OpenFOAM.
    Type of Medium: Online Resource
    ISSN: 2151-2043
    URL: Article
    DOI: 10.1149/MA2021-031196mtgabs
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2438749-6
    Location Call Number Limitation Availability
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    Online Resource
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