Layered YSZ/SCSZ/YSZ Electrolytes for Intermediate Temperature SOFC Part I: Design and Manufacturing

Authors

  • Y. Chen,

    Corresponding author
    1. Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, 4000 Central Florida Blvd., Orlando, Florida 32816, USA
    • Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, 4000 Central Florida Blvd., Orlando, Florida 32816, USA
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  • N. Orlovskaya,

    1. Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, 4000 Central Florida Blvd., Orlando, Florida 32816, USA
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  • M. Klimov,

    1. Materials Characterization Facility, University of Central Florida, 12443 Research Parkway, Suite 304, Orlando, Florida 32826, USA
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  • X. Huang,

    1. Department of Mechanical Engineering and SOFC Program, University of South Carolina, 300 Main Street, Columbia 29208, USA
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  • D. Cullen,

    1. Materials Science and Technology Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
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  • T. Graule,

    1. Empa, Materials Science & Technology, The Laboratory for High Performance Ceramics, Ueberlandstr. 129, CH-8600 Dubendorf, Switzerland
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  • J. Kuebler

    1. Empa, Materials Science & Technology, The Laboratory for High Performance Ceramics, Ueberlandstr. 129, CH-8600 Dubendorf, Switzerland
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Abstract

(Sc2O3)0.1(CeO2)0.01(ZrO2)0.89 (SCSZ) ceramic electrolyte has superior ionic conductivity in the intermediate temperature range (700–800 °C), but it does not exhibit good phase and chemical stability in comparison with 8 mol% Y2O3–ZrO2 (YSZ). To maintain high ionic conductivity and improve the stability in the whole electrolyte, layered structures with YSZ outer layers and SCSZ inner layers were designed. Because of a mismatch of coefficients of thermal expansion and Young's moduli of SCSZ and YSZ phases, upon cooling of the electrolytes after sintering, thermal residual stresses will arise, leading to a possible strengthening of the layered composite and, therefore, an increase in the reliability of the electrolyte. Laminated electrolytes with three, four, and six layers design were manufactured using tape-casting, lamination, and sintering techniques. After sintering, while the thickness of YSZ outer layers remained constant at ∼30 μm, the thickness of the SCSZ inner layer varied from ∼30 μm for a Y–SC–Y three-layered electrolyte, ∼60 μm for a Y–2SC–Y four-layered electrolyte, and ∼120 μm for a Y–4SC–Y six-layered electrolyte. The microstructure, crystal structure, impurities present, and the density of the sintered electrolytes were characterized by scanning and transmission electron microscopy, X-ray and neutron diffraction, secondary ion mass spectroscopy, and water immersion techniques.

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