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

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.

Visualizing the Structural Evolution of LSM/xYSZ Composite Cathodes for SOFC by in-situ Neutron Diffraction

“…Heterogeneous materials, which consist of two or more phases, share many benefits in the energy-converting devices including fuel cells and batteries12345. Taking the solid oxide fuel cell (SOFC) – an electrochemical conversion device with high efficiency, fuel flexibility and low emission, as an example, the electrode of SOFC performing as a reaction chamber requires a combination of both good ionic and electronic conductivities, high catalysis and sometimes good mechanical supporting67.…”

Fabrication and Characterization of YSZ/ScSZ Bilayer Electrolyte via Cold-Isostatic Pressing (CIP) Method for Intermediate Temperature-Solid Oxide Fuel Cell (IT-SOFC) Application

“…Therefore, a YSZ/ScSZ bilayer can provide both phase and chemical stability while have superior ionic conductivity compared to other bilayer combinations to operate in low temperatures [11], [14]- [16], [26], [27]. This shows many researchers are suggesting that bi-layered electrolyte material is a solution for intermediate temperature SOFC operation.…”

“…Also, the functional electrolyte material should supplement the demerits of the main material and thinner. A highly conductive electrolyte material and functional layer structure should be selected to lower the operating temperature and prevent chemical instability [26]. Previous studies show that in most cases, YSZ has been paired with ceria-based materials such as GDC [28], [29] and SDC [28], [30] as base layer.…”

“…Previous studies show that in most cases, YSZ has been paired with ceria-based materials such as GDC [28], [29] and SDC [28], [30] as base layer. There are also studies of bilayering YSZ with ScSZ material, however the layer designs were manufacture via tape-casting and spray coating [26].…”

Pd enhanced WC catalyst to promote heterogeneous methane combustion

“…Under such low catalyst concentrations, the support will prevent loosely distributed powders from sintering and coarsening at high operational temperatures [23] and, thus, the high catalytic activity of CeO2 during methane combustion will be preserved. It is also well know that a combination of CeO2 and ZrO2 oxides can create a rather stable ionically conductive ceramic material which itself could act as a catalyst for the combustion of methane [24,25].…”