Lanthanide (III) oxide added bismuth (III) oxide solid electrolyte material

Abstract

The invention relates particularly to a thermodynamically and chemically stable solid electrolyte material with low electronic and high ionic conductivity used in solid oxide fuel cells and its manufacturing method, wherein; the material comprises Bi2O3 (1), La2O3 (2), Nd2O3 (3), Eu2O3 (4), and Dy2O3 (5). The production method comprises the steps of mixing (11), grinding (12), pressing (13), and heat treatment (14) at specific stoichiometric ratios; and the study of the structural, thermal, and electrical properties of the material comprising X-Ray diffraction analysis (21), thermal analysis (22), electron microscope imaging (23), DC 4-Point conductivity measurement (24), and activation energy calculation (25) steps.

Description

[0001] DESCRIPTION

[0002] LANTHANIDE (III) OXIDE ADDED BISMUTH (III) OXIDE SOLID ELECTROLYTE MATERIAL

[0003] Technical Field:

[0004] The invention relates in particular to a thermodynamically and chemically stable solid electrolyte material with low electronic and high ionic conductivity used in solid oxide fuel cells and its manufacturing method.

[0005] Prior Art:

[0006] The growing population and technological developments are also constantly increasing the global need for energy. The burning of fossil fuels used to meet the energy needs brings along the problems of climate change, air pollution, and energy insecurity. Due to the common goals of economic growth, environmental protection, and energy security, the search for cheap and clean energy is gaining significant importance. The search for an energy source today is evolving toward producing electrical energy from many different sources. In this regard, fuel cells, which generate electrical energy by the electrochemical reaction of a suitable fuel and oxidizer, are critical power systems since there is no need for charging and can continuously generate electrical energy as long as fuel is supplied. Fuels such as hydrogen, butane, propane, ethane, ethanol, methane, methanol, biogas, and naphtha are generally used in fuel cells. Fuel cells are classified according to the type of electrolyte and fuel. Solid oxide fuel cells (SOFCs) are devices consisting of an anode, cathode, and electrolyte components that convert the chemical energy of fuel into electrical energy with high efficiency. A solid oxide fuel cell is characterized by the fact that it has a solid ceramic electrolyte, which is a metallic oxide. The cell reaction for a hydrogen-fueled SOFC is; H2+1 / 2O2— >H2O + electric energy + heat. Zero carbon emissions here indicate that the fuel cell is a decently environmentally friendly power source. SOFC traditionally operates at high temperatures between 800 to 1000 O. The properties that the ideal SOFC electrolyte should have can be listed as follows; having sufficiently high oxide ion conductivity, low electronic conductivity, thermodynamic and chemical stability, chemical inertia against electrode materials, compatibility of the coefficient of thermal expansion with cell components, and reliable mechanical properties. When the literature and patent applications related to solid oxide fuel cell electrolyte materials are examined, it is seen that; a large number of different solid oxide electrolytes such as zirconium materials, cerium materials, lanthanum materials, bismuth oxide-based or pyrochlore-based materials appear to be used. The ideal electrolytes for high- temperature solid oxide fuel cells (HT-SOFC), intermediate temperature solid oxide fuel cells (IT-SOFC), and low-temperature solid oxide fuel cells (LT-SOFC) vary. The choice of an ideal electrolyte depends not only on the operating temperature but also on its physical parameters, such as the power density of the fuel cell, the type of fuel, and current density.

[0007] The most common solid electrolyte material used in solid oxide fuel cells is yttrium- stabilized zirconium (YSZ). Yttria is added to stabilize the conductive cubic fluorite phase and also to increase the concentration of oxygen vacancies and thereby to increase ionic conductivity. Although it is rarely used for zirconium, a promising additive is scandium, which has a higher conductivity than YSZ. The higher conductivity of scandium stabilized zirconia (ScSZ) is attributed to the more minor mismatch in size between Zr4+and Sc3+when compared to Zr4+and Y3+. Like zirconia, cerium forms the fluorite structure and is a common electrolyte material for SOFC. Compared with zirconia, cerium has higher conductivity and lower polarization resistance, especially at low temperatures. The primary disadvantage of cerium is electronic conduction at low oxygen partial pressures. Like zirconia, cerium is doped to increase conductivity, and again like zirconia, the highest conductivity occurs for ions with the lowest size mismatch, which are gadolinium and samarium for cerium. The conductivity of Cei-xGdxO2 (CGO), the most widely used cerium-based electrolyte, is compared to that of YSZ and ScSZ. Below 600 G, the conductivities of CGO are consistently higher than those of YSZ or ScSZ. Perovskite, LaGaOs, strontium, and magnesium can be doped with Lai-xSrxGai-yMgyO3 (LSGM) to produce a material with good oxygen ion conductivity at low temperature. The conductivity of LSGM is higher than the conductivity of YSZ and SCSZ and is close to or lower than the conductivity of CGO. However, LSGM does not have an easily reducible ion like Ce4+and is therefore superior to cerium-based gadolinium oxide (CGO) for use at low oxygen partial pressures. The highest ionic conductivities at 300-700 G are found in Bi 203-based electrolytes such as Bismuth metal vanadium oxide (BIMEVOX). At temperatures as low as 300 G, BIMEVOX electrolytes exhibit conductivity as high as YSZ at 800 G. The patent no. CN103904351 A relates to a scandium oxide doped bismuth oxide solid oxide fuel cell electrolyte and a preparation method thereof. The patent no. CN108134119A relates to a kind of solid oxide fuel cell bismuth oxide base electrolyte membrane preparation method. It uses tungsten oxide, yttrium oxide, and magnesia codoped bismuth oxide. The patent no. CN110165268A is related to a kind of calcium carbonate collaboration promotion bismuth oxide method for preparing composite solid electrolyte, is related to solid electrolyte ceramic technical field of material. The patent no. FR2792306A1 relates to a substituted bismuth-molybdenum oxide solid solution composition has substituting elements selected for maintaining charge equilibrium and structure type. A novel composition comprises a substituted BI26M010O69 solid solution in which the substituting elements are selected for maintaining charge equilibrium and the structure type.

[0008] Bismuth (Bi) is a post-transition metal with atomic number 83, an atomic mass of 208,980 g / mol, and a melting point of 271 .4 C, in the 15th group (5A) and 6th period in the periodic table. Bismuth (III) oxide (Bi20s) has a mass of 465.957 g / mol. Pure Bi20s has six different crystallographic structures depending on the temperature. These are; monoclinic a- phase, tetragonal p-phase, bcc-body-centered cubic y-phase, fcc-surface-centered cubic 5-phase, orthorhombic 5-phase, and triclinic w-phase. The electrolyte is expected to be in a stable fcc-surface centered cubic s-phase. The 6-phase of Bi20s, which is stable only at high temperatures, exhibits an exceptionally high anionic conductivity (~ 100 Snr1). This anionic conductor is considered a possible solid-state electrolyte for use in high- temperature oxygen pumps and different gas sensors.

[0009] The Purpose of Invention:

[0010] The search for the ideal electrolyte with high ionic conductivity at low temperature, as well as minimal electronic conductivity and low activation energy, is ongoing in the industry, especially for solid oxide fuel cells. Studies conducted in this context indicate that Bi20s- based electrolytes will meet a critical need. To achieve this goal, the invention provides the following technical solutions;

[0011] • Sufficiently high oxide-ion conductivity (0.1 S / cm at operating temperature).

[0012] • Low electronic conductivity (<1 O'3S / cm).

[0013] • Thermodynamic and chemical stability.

[0014] • Chemical inertness to electrode materials. • Compatibility of the coefficient of thermal expansion with the components of the cell.

[0015] • Having reliable mechanical properties.

[0016] The benefits of the invention in comparison with the prior art are as follows;

[0017] • Sufficiently high oxide-ion conductivity (approximately 5 S / cm at operating temperature).

[0018] • Low electronic conductivity (<1 O'6S / cm).

[0019] • Thermodynamic and chemical stability (obtaining samples with stable structure in the delta phase)

[0020] Description of Figures:

[0021] The details of the invention called Lanthanide (III) Oxide Added Bismuth (III) Oxide Solid Electrolyte Material are shown in the attached figures. In these figures;

[0022] Figure 1 : Lanthanide (III) Oxide Added Bismuth (III) Oxide Solid Electrolyte Material

[0023] Figure 2: The X-Ray Diffraction Pattern of a Sample

[0024] Figure 3: The Graph of the Thermal Analysis of a Sample

[0025] Figure 4: Field Emission Scanning Electron Microscope Image of a Sample

[0026] Figure 5: A Graph of the Temperature-Dependent Conductivity of a Sample

[0027] Figure 6: Activation Energy of a Sample

[0028] Description of the References in the Figures:

[0029] 1 : Bismuth (III) Oxide: Bi20s

[0030] 2: Lanthanum (III) Oxide: La2Os

[0031] 3: Neodymium (III) Oxide: Nd20a

[0032] 4: Europium (III) Oxide: EU2O3

[0033] 5: Dysprosium (III) Oxide: Dy20s

[0034] Methods Applied in the Production of Materials:

[0035] 11 : Mixing

[0036] 12: Grinding

[0037] 13: Pressing

[0038] 14: Heat Treatment Methods of Analysis of Manufactured Materials:

[0039] 21 : X-Ray Diffraction (XRD) Analysis

[0040] 22: Thermal (TG / DTG / DTA) Analysis

[0041] 23: Field Emission Scanning Electron Microscope (FESEM) Image

[0042] 24: DC 4-Point Conductivity Measurement

[0043] 25: Calculation of Activation Energy

[0044] Description of the Invention:

[0045] Characterized by the chemical formula (Bi2O3)i-x-y-z-t(Eu2O3)x(La2O3)y(Nd2O3)z(Dy2O3)t, nano powder La2O3(2), Nd2O3(3), Eu2O3(4), Dy20s(5) added nano powder Bi2O3(1 ) materials were mixed in molar ratios of x,y,z,t=[5%-20%]. (II) A large number of mixtures of different stoichiometric ratios were grounded (12). Solid oxide electrolyte materials were produced in the required geometric shapes and sizes by pressing (13) the nanopowder materials under a pressure of around 750 MPa. The manufactured materials were subjected to heat treatment (14) for 100 hours at 800 <C in an atmospheric environment. X-ray diffraction (XRD) analysis (21 ) was performed to examine the phase structure and crystallographic properties of the materials produced. In the XRD analysis, patterns indicating the delta phase were observed. In order to study the thermal properties of the materials, thermogravimetric, differential thermogravimetric, and differential thermal (TG / DTG / DTA) analyses (22) were performed. A field emission scanning electron microscope (FESEM) image (23) was taken for the surface characterization of the materials. The temperature-dependent conductivity of the produced materials in the range of 25 C - 1 150 T was measured by DC 4-point conductivity measurement (24) technique, and the activation energy was calculated from the obtained data (25). The maximum conductivity was measured at 5.23 S / cm. This value is relatively high compared to the conductivity of similar samples in the literature.

[0046] Industrial Application of the Invention:

[0047] Lanthanide (III) Oxide Added Bismuth (III) Oxide Solid Electrolyte Material, which is the subject of the invention, is suitable for mass production, particularly to be used as an electrolyte in high temperature and medium temperature solid oxide fuel cells.

Claims

CLAIMS The invention relates particularly to a thermodynamically and chemically stable solid electrolyte material with low electronic and high ionic conductivity used in solid oxide fuel cells and its manufacturing method, characterized by comprising; Bismuth (III) Oxide: Bi20a (1 ), Lanthanum (III) Oxide: La20a (2), Neodymium (III) Oxide: Nd20a (3), Europium (III) Oxide: EU2O3 (4), and Dysprosium (III) Oxide: Dy20a (5). The invention relates particularly to a thermodynamically and chemically stable solid electrolyte material with low electronic and high ionic conductivity used in solid oxide fuel cells and its manufacturing method, according to Claim 1 , characterized by comprising; Bi20s (1 ) at a molar ratio ranging from 20% to 80%. The invention relates particularly to a thermodynamically and chemically stable solid electrolyte material with low electronic and high ionic conductivity used in solid oxide fuel cells and its manufacturing method, according to Claim 1 , characterized by comprising; La20s (2) at a molar ratio ranging from 5% to 20%. The invention relates particularly to a thermodynamically and chemically stable solid electrolyte material with low electronic and high ionic conductivity used in solid oxide fuel cells and its manufacturing method, according to Claim 1 , characterized by comprising; Nd20s (3) at a molar ratio ranging from 5% to 20%. The invention relates particularly to a thermodynamically and chemically stable solid electrolyte material with low electronic and high ionic conductivity used in solid oxide fuel cells and its manufacturing method, according to Claim 1 , characterized by comprising; EU2O3 (4) at a molar ratio ranging from 5% to 20%. The invention relates particularly to a thermodynamically and chemically stable solid electrolyte material with low electronic and high ionic conductivity used in solid oxide fuel cells and its manufacturing method, according to Claim 1 , characterized by comprising; Dy20s (5) at a molar ratio ranging from 5% to 20%. The invention relates particularly to a thermodynamically and chemically stable solid electrolyte material with low electronic and high ionic conductivity used in solid oxide fuel cells and its manufacturing method, characterized in that; the production method comprises the steps of mixing (1 1 ), grinding (12), pressing(13) and heat treatment (14) at specific stoichiometric ratios. The invention relates particularly to a thermodynamically and chemically stable solid electrolyte material with low electronic and high ionic conductivity used in solid oxide fuel cells and its manufacturing method, characterized in that; the study of the structural, thermal and electrical properties of the material comprisesX-Ray diffraction analysis (21 ), thermal analysis (22), electron microscope imaging (23), DC 4-Point conductivity measurement (24), and activation energy calculation (25) steps.

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