WO2014050124A1 - Electrolyte sheet for solid oxide fuel cell, electrolyte-supporting cell, single cell for solid oxide fuel cell, and solid oxide fuel cell - Google Patents

Electrolyte sheet for solid oxide fuel cell, electrolyte-supporting cell, single cell for solid oxide fuel cell, and solid oxide fuel cell Download PDF

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WO2014050124A1
WO2014050124A1 PCT/JP2013/005745 JP2013005745W WO2014050124A1 WO 2014050124 A1 WO2014050124 A1 WO 2014050124A1 JP 2013005745 W JP2013005745 W JP 2013005745W WO 2014050124 A1 WO2014050124 A1 WO 2014050124A1
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oxide
mol
zirconia
electrolyte
rare earth
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PCT/JP2013/005745
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French (fr)
Japanese (ja)
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秦　和男
西川　洋平
相川　規一
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株式会社日本触媒
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Priority to CN201380049722.XA priority Critical patent/CN104685684B/en
Priority to JP2014538196A priority patent/JP5890908B2/en
Publication of WO2014050124A1 publication Critical patent/WO2014050124A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
    • H01M8/124—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte
    • H01M8/1246—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte the electrolyte consisting of oxides
    • H01M8/126—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte the electrolyte consisting of oxides the electrolyte containing cerium oxide
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
    • H01M8/124—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte
    • H01M8/1246—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte the electrolyte consisting of oxides
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    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
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    • C04B35/48—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zirconium or hafnium oxides, zirconates, zircon or hafnates
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    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/48—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zirconium or hafnium oxides, zirconates, zircon or hafnates
    • C04B35/486—Fine ceramics
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
    • H01B1/08—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances oxides
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3224—Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3224—Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
    • C04B2235/3229—Cerium oxides or oxide-forming salts thereof
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/74—Physical characteristics
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
    • H01M2008/1293—Fuel cells with solid oxide electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0065—Solid electrolytes
    • H01M2300/0068—Solid electrolytes inorganic
    • H01M2300/0071—Oxides
    • H01M2300/0074—Ion conductive at high temperature
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0088—Composites
    • H01M2300/0091—Composites in the form of mixtures
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to an electrolyte sheet for a solid oxide fuel cell, an electrolyte supporting cell using the same, a single cell for a solid oxide fuel cell, and the electrolyte supporting cell or the solid oxide fuel cell.
  • the present invention relates to a solid oxide fuel cell including a single cell.
  • SOFC solid oxide fuel cells
  • the SOFC has a structure in which a solid electrolyte layer made of ceramic is disposed between an air electrode and a fuel electrode as a basic structure.
  • oxygen in the air introduced into the air electrode receives electrons and becomes oxygen ions (O 2 ⁇ ), and the oxygen ions move through the solid electrolyte layer and reach the fuel electrode. Electrons are released when oxygen ions that have reached the fuel electrode react electrochemically with hydrogen at the fuel electrode, and an electrical output is obtained.
  • the solid electrolyte layer is required to have characteristics such as high oxygen ion conductivity and high material strength. Therefore, the solid electrolyte layer generally includes zirconia (yttria stabilized zirconia (YSZ)) to which yttria (Y 2 O 3 ) is added and zirconia (scandia stabilization to which scandia (Sc 2 O 3 ) is added).
  • YSZ zirconia
  • a sintered body such as a zirconia-based oxide such as zirconia (ScSZ) is used.
  • Patent Document 1 proposes various materials for a solid electrolyte layer that can realize a stable crystal phase in addition to high oxygen ion conductivity and high material strength.
  • an object of the present invention is to provide an SOFC electrolyte sheet that can suppress a change with time in oxygen ion conductivity even when exposed to an atmosphere containing a sulfur component. Furthermore, the present invention also provides an electrolyte-supported cell, a single cell for SOFC, and a SOFC that can suppress a decrease in durability even when fuel containing a sulfur component is supplied to the fuel electrode. Objective.
  • the first aspect of the present invention is: Including electrolyte components,
  • the electrolyte component is a zirconia-based oxide that is stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ) and contains a rare earth oxide of 0.003 mol% or more and less than 0.5 mol%.
  • the rare earth oxide is an oxide of at least one element selected from rare earth elements excluding Sc and Ce.
  • An electrolyte sheet for SOFC is provided.
  • the second aspect of the present invention is: Including electrolyte components,
  • the electrolyte component is composed of a zirconia-based oxide that is stabilized with scandium oxide (Sc 2 O 3 ) and contains a rare earth oxide of 0.003 mol% or more and less than 0.5 mol%,
  • the rare earth oxide is an oxide of at least one element selected from rare earth elements excluding Sc.
  • An electrolyte sheet for SOFC is provided.
  • the third aspect of the present invention is: Provided is an electrolyte-supporting cell comprising a fuel electrode, an air electrode, and the SOFC electrolyte sheet according to the first aspect or the second aspect disposed between the fuel electrode and the air electrode.
  • the fourth aspect of the present invention is: A fuel electrode, an air electrode, and a solid electrolyte layer disposed between the fuel electrode and the air electrode, At least one selected from the fuel electrode, the air electrode, and the solid electrolyte layer is stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ), and is 0.003 mol% or more and 0 A zirconia-based oxide containing less than 5 mol% rare earth oxide as an electrolyte component;
  • the rare earth oxide is an oxide of at least one element selected from rare earth elements excluding Sc and Ce.
  • a single cell for SOFC is provided.
  • a zirconia oxide containing oxide is included as an electrolyte component, The rare earth oxide is an oxide of at least one element selected from rare earth elements excluding Sc.
  • a single cell for SOFC is provided.
  • the sixth aspect of the present invention is: An SOFC comprising the electrolyte-supporting cell according to the third aspect, the SOFC single cell according to the fourth aspect, or the SOFC single cell according to the fifth aspect is provided.
  • the SOFC electrolyte sheet according to the first and second aspects of the present invention can suppress changes in oxygen ion conductivity over time even when exposed to an atmosphere containing a sulfur component.
  • the electrolyte supporting cell according to the third aspect of the present invention includes such an electrolyte sheet for SOFC, durability is ensured even when a fuel containing a sulfur component is supplied to the fuel electrode. Can be kept small.
  • the SOFC single cell according to the fourth and fifth aspects of the present invention is exposed to an atmosphere containing a sulfur component, the oxygen ion conductivity of the solid electrolyte layer changes with time, or the electrode. Since the change with time of the activity can be suppressed to a small level, it is possible to suppress a decrease in durability.
  • the SOFC according to the sixth aspect of the present invention includes the electrolyte-supporting cell according to the third aspect, the SOFC single cell according to the fourth aspect, or the SOFC single cell according to the fifth aspect, Even when exposed to an atmosphere containing a sulfur component, a decrease in durability can be minimized.
  • the electrolyte sheet of the present embodiment includes an electrolyte component, and the electrolyte component is It is stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ), and is rare earth oxide (hereinafter referred to as rare earth oxide A) of 0.003 mol% or more and less than 0.5 mol%. ) Containing at least one element selected from rare earth elements excluding Sc and Ce.
  • rare earth oxide B a rare earth oxide of 0.003 mol% or more and less than 0.5 mol%
  • the rare earth oxide B is an oxide of at least one element selected from rare earth elements excluding Sc.
  • 0.003 mol% or more and less than 0.5 mol% rare earth oxide A means that the total amount of rare earth oxide A is 0.003 mol% or more and less than 0.5 mol%. means.
  • the rare earth oxide B of 0.003 mol% or more and less than 0.5 mol% means that the total amount of the rare earth oxide B is 0.003 mol% or more and less than 0.5 mol%. . The same applies to the subsequent steps.
  • the electrolyte sheet of the present embodiment includes an electrolyte component, and the electrolyte component is a trace amount of 0.003 mol% or more and less than 0.5 mol% in zirconia stabilized with scandium oxide (Sc 2 O 3 ).
  • cerium oxide (CeO 2 ) functions as a stabilizer for zirconia
  • other rare earth element oxides other than Ce are 0.003 mol% or more and 0.5 mol%. It is characterized by being a zirconia-based oxide (scandiaceria-stabilized zirconia-based oxide) added in a range of less than%.
  • the electrolyte sheet of the present embodiment having the above-described configuration can suppress a decrease in oxygen ion conductivity even when exposed to an atmosphere containing a sulfur component. Therefore, even when hydrogen generated by reforming city gas is used as a fuel and the fuel may contain a sulfur component, the electrolyte sheet of this embodiment is used as the SOFC. It can be suitably used as a solid electrolyte layer.
  • a desulfurization device is often provided along with the reformer.
  • a desulfurization apparatus may not be provided in a system in which an internal reforming SOFC that directly reforms city gas in the SOFC is used. Therefore, the electrolyte sheet of the present embodiment exhibits excellent effects particularly when applied to an internal reforming SOFC solid electrolyte layer.
  • the electrolyte component contained in the electrolyte sheet of the present embodiment is a form that is the scandiaceria-stabilized zirconia-based oxide (form 1-A) and a form that is the scandia-stabilized zirconia-based oxide (form 1). -B) will be described respectively.
  • Form 1-A sinandiaceria-stabilized zirconia oxide
  • the electrolyte component contained as the main component of the electrolyte sheet according to Form 1-A is stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ), and is 0.003 mol% or more and 0.5 mol It is comprised with the zirconia-type oxide containing the rare earth oxide A of less than%.
  • the rare earth oxide A is an oxide of at least one element selected from rare earth elements excluding Sc and Ce.
  • the rare earth oxide A is at least one selected from the group consisting of Y, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. It is an oxide of an element.
  • 0.003 mol% or more and less than 0.5 mol% of rare earth oxide A is further dissolved in zirconia in which scandium oxide and cerium oxide are dissolved as stabilizers.
  • the zirconia-based oxide sintered body is formed.
  • the total amount of rare earth oxide A in the zirconia-based oxide is preferably 0.005 mol% or more and 0.4 mol% or less, and more preferably 0.01 mol% or more and 0.3 mol% or less.
  • Rare earth oxide A contained in a trace amount in the range of 0.003 mol% or more and less than 0.5 mol% in a zirconia-based oxide stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ) Has the effect of suppressing the formation of a compound of an electrolyte component and a sulfur component, deposition and adhesion of the sulfur component to the electrolyte surface, and the like.
  • the content of the rare earth oxide A is less than 0.003 mol%, the effect of suppressing the adverse effect of the sulfur component due to the rare earth oxide A on the electrolyte component is not sufficiently exhibited, and the electrolyte sheet is in an atmosphere containing the sulfur component. When exposed, it is difficult to keep the oxygen ion conductivity change with time small.
  • the content of the rare earth oxide A is 0.5 mol% or more, it is expected that the sulfur component is likely to be deposited and adhered to the surface of the electrolyte, or to react easily with the electrolyte component. As a result, the conductivity of the electrolyte sheet gradually deteriorates as the inflow of fuel proceeds. Therefore, if the zirconia-based oxide constituting the electrolyte component contains the rare earth oxide A excessively, the change with time of the conductivity of the electrolyte sheet becomes large.
  • the rare earth oxide A contained as a trace component is selected from the group consisting of Y, La, Pr, Nd, Sm, Gd and Yb in order to more reliably suppress the temporal change in oxygen ion conductivity caused by the sulfur component. It is preferably an oxide of at least one element selected from the group consisting of Y, Sm, Gd, and Yb, and more preferably an oxide of at least one element selected from the group consisting of Y, Sm, Gd, and Yb.
  • the rare earth oxide A is gadolinium oxide (Gd 2 O 3 ).
  • gadolinium oxide (Gd 2 O 3 ) is contained as the rare earth oxide A in the zirconia-based oxide in Form 1-A, among other rare earth oxides, formation of a compound of an electrolyte component and a sulfur component, Highly effective in suppressing the deposition and adhesion of sulfur components to the electrolyte surface. Therefore, when the zirconia-based oxide in Form 1-A contains gadolinium oxide (Gd 2 O 3 ) as the rare earth oxide A, the change over time in the oxygen ion conductivity caused by the sulfur component can be further suppressed to be small. Can do.
  • zirconia oxide in Embodiment 1-A contains gadolinium oxide (Gd 2 O 3), content is 0.2 mol% or less than 0.003 mole percent gadolinium oxide (Gd 2 O 3) It is preferable. This is because when the content of gadolinium oxide (Gd 2 O 3 ) exceeds 0.2 mol%, the effect cannot be enhanced to the extent that it matches the content of gadolinium oxide.
  • the zirconia-based oxide in Form 1-A contains gadolinium oxide (Gd 2 O 3 ), it is preferable that yttrium oxide (Y 2 O 3 ) is further added as the rare earth oxide A.
  • the electrolyte component of the electrolyte sheet of Form 1-A is composed of a zirconia-based oxide containing both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) as the rare earth oxide A, The effect of suppressing the adverse effect of the sulfur component on the electrolyte component can be further improved.
  • the content of yttrium oxide (Y 2 O 3 ) is 0.003. A particularly excellent effect can be obtained when the content is in the range of from mol% to 0.2 mol%.
  • the zirconia-based oxide in Form 1-A preferably contains scandium oxide (Sc 2 O 3 ) in an amount of 8 mol% to 15 mol%, and contains 8.5 mol% to 12 mol%. It is more preferable that it is contained in an amount of 9 mol% or more and 11 mol% or less.
  • the zirconia-based oxide in Form 1-A preferably has a cubic crystal structure. When the crystal structure includes cubic crystals, the zirconia-based oxide in Form 1-A preferably contains scandium oxide (Sc 2 O 3 ) in an amount of 9.5 mol% to 12 mol%. More preferably, it is contained in an amount of 10 mol% to 11.5 mol%.
  • the zirconia-based oxide in Form 1-A preferably contains cerium oxide (CeO 2 ) in an amount of 0.5 mol% or more and 2.5 mol% or less, and contains 0.6 mol% or more and 2 mol% or less. It is more preferable that it is contained in an amount of 0.7 mol% or more and 1.5 mol% or less.
  • CeO 2 cerium oxide
  • Form 1-B sinandia-stabilized zirconia oxide
  • the electrolyte component contained as a main component of the electrolyte sheet according to Form 1-B is stabilized with scandium oxide (Sc 2 O 3 ), and is rare earth oxide B having a content of 0.003 mol% or more and less than 0.5 mol%. It is comprised with the zirconia-type oxide containing.
  • the rare earth oxide B is an oxide of at least one element selected from rare earth elements excluding Sc. That is, the rare earth oxide B is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.
  • 0.003 mol% or more and less than 0.5 mol% of rare earth oxide B is further dissolved in zirconia in which scandium oxide is dissolved as a stabilizer. It is formed of a sintered body of zirconia oxide.
  • the total amount of rare earth oxide B in the zirconia-based oxide is preferably 0.005 mol% to 0.4 mol%, and more preferably 0.01 mol% to 0.3 mol%.
  • the decrease in the electrical conductivity of the electrolyte sheet that occurs in an atmosphere containing a sulfur component occurs due to the electrolyte component forming a compound with the sulfur component, or the sulfur component being deposited on or attached to the electrolyte surface.
  • the rare earth oxide B contained in a trace amount within the range of 0.003 mol% to less than 0.5 mol% is composed of an electrolyte component and a sulfur component. It has the effect of suppressing the formation of the compound and the deposition and adhesion of sulfur components to the electrolyte surface.
  • the content of the rare earth oxide B is less than 0.003 mol%, the effect of suppressing the adverse effect of the sulfur component due to the rare earth oxide B on the electrolyte component is not sufficiently exhibited, and the electrolyte sheet is in an atmosphere containing the sulfur component. When exposed, it is difficult to keep the oxygen ion conductivity change with time small. Further, when the content of the rare earth oxide B is 0.5 mol% or more, it is expected that the sulfur component easily deposits and adheres to the surface of the electrolyte or reacts easily with the electrolyte component. As a result, the conductivity of the electrolyte sheet gradually deteriorates as the inflow of fuel proceeds. Accordingly, when the zirconia-based oxide constituting the electrolyte component contains the rare earth oxide B excessively, the change with time of the conductivity of the electrolyte sheet becomes large.
  • the rare earth oxide B contained as a trace component is a group consisting of Y, La, Ce, Pr, Nd, Sm, Gd, and Yb in order to more reliably suppress the temporal change in oxygen ion conductivity caused by the sulfur component.
  • the oxide is an oxide of at least one element selected from the group consisting of Y, Ce, Sm, Gd, and Yb. More preferred.
  • the rare earth oxide B is cerium oxide (CeO 2 ).
  • cerium oxide (CeO 2 ) is contained as rare earth oxide B in the zirconia-based oxide in Form 1-B, among other rare earth oxides, formation of a compound of an electrolyte component and a sulfur component, Highly effective in suppressing deposition and adhesion of sulfur components. Therefore, when the zirconia-based oxide in Form 1-B contains cerium oxide (CeO 2 ) as the rare earth oxide B, the change over time in the oxygen ion conductivity caused by the sulfur component can be more reliably suppressed. .
  • the zirconia-based oxide in Form 1-B contains cerium oxide (CeO 2 )
  • its content is preferably 0.1 mol% or more, more preferably 0.2 mol% or more.
  • its content is preferably 0.48 mol% or less, and more preferably 0.45 mol% or less.
  • the zirconia-based oxide in Form 1-B when the rare earth oxide B is gadolinium oxide (Gd 2 O 3 ), a high effect of suppressing change with time in oxygen ion conductivity can be obtained.
  • the zirconia-based oxide in Form 1-B contains gadolinium oxide (Gd 2 O 3 ), its content is preferably 0.003 mol% or more and 0.2 mol% or less, and 0.005 mol% or more 0.1 mol% or less is more preferable.
  • the zirconia-based oxide in Form 1-B when the rare earth oxide B is yttrium oxide (Y 2 O 3 ), a high effect of suppressing the change in oxygen ion conductivity with time can be obtained.
  • the zirconia-based oxide in Form 1-B contains yttrium oxide (Y 2 O 3 )
  • its content is preferably 0.003 mol% or more and 0.2 mol% or less, and 0.005 mol% or more 0.1 mol% or less is more preferable.
  • the zirconia-based oxide in Form 1-B may contain both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) as rare earth oxide B.
  • the electrolyte component of the electrolyte sheet of Form 1-B is composed of a zirconia-based oxide containing both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) as rare earth oxide B. The effect of suppressing the adverse effect of the sulfur component on the electrolyte component can be further improved.
  • gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) are not clear, but gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O). 3 ) is preferably from 0.003 mol% to 0.2 mol%, more preferably from 0.005 mol% to 0.1 mol%.
  • the zirconia-based oxide in Form 1-B preferably contains scandium oxide (Sc 2 O 3 ) in an amount of 4 mol% to 15 mol%.
  • the zirconia-based oxide contains scandium oxide (Sc 2 O 3 ) in an amount of 4 mol% to 6.5 mol%. Is preferred.
  • the zirconia-based oxide preferably contains scandium oxide (Sc 2 O 3 ) in an amount of 9 mol% to 13 mol%. 9.5 mol% or more and 12 mol% or less, more preferably 10 mol% or more and 11.5 mol% or less.
  • the cubic system means stabilized zirconia whose crystal structure is mainly composed of cubic crystals. Specifically, each peak intensity is obtained from the X-ray diffraction pattern of the zirconia crystal in the solid electrolyte sheet, and the cubic ratio (%) obtained from each intensity value and the following formula is 50% or more.
  • the cubic stabilized zirconia preferably has a cubic ratio of 90% or more, more preferably 95% or more, and still more preferably 97% or more.
  • Cubic crystal ratio (%) (100 ⁇ monoclinic crystal ratio) ⁇ [c (400)] ⁇ [t (400) + t (004) + c (400)] [Wherein c (400) represents the peak intensity of the cubic (400) plane, t (400) represents the peak intensity of the tetragonal (400) plane, and t (004) represents the tetragonal (004) plane. Shows peak intensity]
  • the tetragonal system means stabilized zirconia whose crystal structure is mainly tetragonal. Specifically, each peak intensity is obtained from the X-ray diffraction pattern of the zirconia crystal in the solid electrolyte sheet, and the tetragonal crystal ratio (%) obtained from each intensity value and the following formula is 50% or more.
  • Tetragonal stabilized zirconia Tetragonal crystal ratio (%) (100 ⁇ monoclinic crystal ratio) ⁇ [t (400) + t (004)] ⁇ [t (400) + t (004) + c (400)] [Where t (400) represents the peak intensity of the tetragonal (400) plane, t (004) represents the peak intensity of the tetragonal (004) plane, and c (400) represents the cubic (400) plane. Shows peak intensity]
  • the electrolyte sheet of the present embodiment refers to both the electrolyte sheet of Form 1-A and the electrolyte sheet of Form 1-B), for example, hafnium oxide other than the above components And oxides such as aluminum oxide, titanium oxide, niobium oxide, tantalum oxide, and manganese oxide, and composite oxides such as LaAlO 3 , MgAl 2 O 4 , Al 2 TiO 5, and LaGaO 3 in a total amount of 5% by mass or less. It may be further included in the range.
  • Li, Na, K, Mg, Ca, Sr, Ba, La, Pr, Nd, Yb, Cr, W, Fe, Co, Ni, Cu, Zn, B, Ga, Si, Ge, P, etc. are included. It may be. In that case, the total content of these components is preferably 1.0% by mass or less in terms of oxide.
  • the form of the electrolyte sheet of the present embodiment is not particularly limited, and examples thereof include a flat plate shape, a curved shape, a film shape, a cylindrical shape, a cylindrical flat plate shape, and a honeycomb shape.
  • the thickness of the electrolyte sheet of the present embodiment can be, for example, 10 ⁇ m or more and 400 ⁇ m or less.
  • the thickness of the electrolyte sheet is preferably, for example, 80 ⁇ m or more and 400 ⁇ m or less, and more preferably 90 ⁇ m or more and 300 ⁇ m or less.
  • Electrolytes size of the sheet of the present embodiment is not particularly limited, for example, 50 cm 2 or more 900 cm 2 or less, preferably electrolyte sheet having a planar area of 70cm 2 or more 500 cm 2 or less are preferably used.
  • the shape of the sheet may be any of a circle, an ellipse, and a square with R (R).
  • These sheets may have one or two or more holes such as a similar circular shape, an elliptical shape, and a rectangular shape having R (R).
  • the said plane area means the area (area determined by sheet
  • the electrolyte sheet of this embodiment a general method for manufacturing an electrolyte sheet for SOFC can be used. That is, the electrolyte sheet of this embodiment can be obtained by preparing a green sheet for an electrolyte sheet and firing the green sheet.
  • a zirconia-based oxide raw material powder used as a raw material for the electrolyte component of the electrolyte sheet of the present embodiment is prepared.
  • any method can be used as long as it is a method capable of producing a powder, but in this embodiment, a coprecipitation method which is a liquid phase process is preferably used.
  • the raw material powder of the electrolyte sheet of the present embodiment includes a solution containing a zirconium compound and a scandium compound, and a rare earth element compound such as a cerium compound, a gadolinium compound, and an yttrium compound, which are appropriately selected as necessary, and a precipitant. It can be obtained by mixing and coprecipitating, and baking the obtained precipitate in an oxidizing atmosphere.
  • the raw material of each component used in the present embodiment is not particularly limited, and examples thereof include inorganic acid salts such as nitrates, carbonates, sulfates, chlorides and oxychlorides, and organic acid salts such as acetates and oxalates.
  • inorganic acid salts such as nitrates, carbonates, sulfates, chlorides and oxychlorides
  • organic acid salts such as acetates and oxalates.
  • nitrates, chlorides and oxychlorides are preferably used.
  • dissolving each raw material in a solvent and obtaining a solution should just be a method which can melt
  • the solvent include water and alcohols.
  • the precipitating agent to be added is not particularly limited, and examples thereof include bases such as sodium hydroxide, potassium hydroxide, sodium carbonate, ammonium carbonate and ammonia. Among these, it is particularly preferable to use ammonia. These precipitating agents are usually preferably added as a solution.
  • the mixing method of the solution containing the raw materials of each component and the precipitant is not particularly limited. Examples thereof include a method of dropping a precipitant solution into a solution containing the raw materials of each component, a method of dropping a solution containing the raw materials of each component into the precipitant solution, and the like.
  • the precipitate produced by the above method can be recovered by solid-liquid separation by washing with water and filtering.
  • the obtained precipitate is usually baked after drying to become an oxide.
  • This firing may be performed in an oxidizing atmosphere, and is preferably performed in the air.
  • the firing temperature is not particularly limited, but is usually about 500 to 1300 ° C., preferably about 600 to 1200 ° C. When the firing temperature is less than 500 ° C., the precipitate may not be sufficiently oxidized. When the firing temperature exceeds 1300 ° C., strong aggregation may occur due to grain growth.
  • the obtained oxide may be pulverized as necessary.
  • the method of pulverization is not particularly limited, and examples thereof include wet pulverization and dry pulverization.
  • the crystal structure of the zirconia-based oxide of the present embodiment is preferably a cubic phase single phase or a tetragonal single phase.
  • the crystal structure of the electrolyte material may be a mixed phase of a cubic phase and a rhombohedral phase (R phase) that includes a slight amount of rhombohedral phase as long as there is no problem in strength and oxygen ion conductivity.
  • the crystal structure of the electrolyte material has a monoclinic phase, a cubic phase, and a tetragonal phase, with a slight monoclinic phase and cubic phase, as long as there is no problem in strength and oxygen ion conductivity. It may be a mixed phase.
  • a green sheet for an electrolyte sheet is produced using the obtained raw material powder.
  • a tape forming method is preferably used, and in particular, a doctor blade method and a calendar method are preferably used.
  • a binder and an additive are added to the zirconia-based oxide raw material powder obtained by the above method, and a dispersion medium or the like is further added as necessary to prepare a slurry. This slurry is spread on a support plate or a carrier film and formed into a sheet shape, which is dried to volatilize the dispersion medium to obtain a green sheet.
  • the green sheet is made into an appropriate size by cutting and / or punching or the like to produce a green sheet for an electrolyte sheet.
  • the binder, the solvent, the dispersant, and the like used for the preparation of the slurry a known binder, a solvent, a dispersant, and the like that are used for manufacturing the SOFC electrolyte sheet can be used.
  • the green sheet for the electrolyte sheet is fired.
  • the green sheet for an electrolyte sheet obtained as described above is placed on a porous setter on a shelf board.
  • the porous setter and the green sheet for the electrolyte sheet produced as described above are alternately stacked on the shelf so that the porous setter is disposed in the lowermost layer and the uppermost layer, You may arrange
  • the green sheet thus arranged is heated and fired at a temperature of about 1200 to 1500 ° C., preferably about 1250 to 1425 ° C. for about 1 to 5 hours.
  • the firing temperature exceeds 1500 ° C.
  • rhombohedral crystals and monoclinic crystals are formed in the sintered body, and both the strength at normal temperature (room temperature strength) and high-temperature durability of the electrolyte sheet may deteriorate.
  • the firing temperature is less than 1200 ° C.
  • firing in the above temperature range suppresses the formation of monoclinic crystals and rhombohedrons, and the relative density of the obtained sheet can be 97% or more, preferably 99% or more.
  • the relative density is a relative value of density measured by Archimedes method with respect to theoretical density (density measured by Archimedes method / theoretical density).
  • the well-known porous setter used for manufacture of the electrolyte sheet for SOFC can be used for the porous setter used for baking of a green sheet.
  • zirconia powder stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ), or zirconia powder stabilized with scandium oxide (Sc 2 O 3 ), a rare earth oxide, and a rare earth element It is also possible to sequentially prepare a slurry, a green sheet, and an electrolyte sheet using a metal-containing metal or a compound containing a rare earth element as a raw material powder.
  • zirconia powder previously stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ) containing rare earth elements, or stabilized with scandium oxide (Sc 2 O 3 ). It is also possible to use a zirconia powder made.
  • FIG. 1 is a cross-sectional view showing an example of the configuration of the electrolyte-supporting cell of the present embodiment.
  • the electrolyte support cell 1 of the present embodiment includes a fuel electrode 11, an air electrode 12, and an SOFC electrolyte sheet 13 disposed between the fuel electrode 11 and the air electrode 12.
  • the electrolyte sheet 13 the SOFC electrolyte sheet described in Embodiment 1 (the electrolyte sheet of Form 1-A or Form 1-B) is used.
  • the fuel electrode 11 and the air electrode 12 a fuel electrode and an air electrode used in a known SOFC can be applied, respectively.
  • the fuel electrode 11 is formed on one main surface of the electrolyte sheet obtained by the method described in the first embodiment, and the air electrode 12 is formed on the other main surface.
  • a binder and a solvent are added to the powder of the material constituting the fuel electrode 11 or the air electrode 12, and a dispersant is added as necessary to prepare a slurry.
  • This slurry is applied to one or the other main surface of the electrolyte sheet 13 with a predetermined thickness, and the coating layer is dried to form a green layer for the fuel electrode 11 or the air electrode 12. By firing the green layer, the fuel electrode 11 or the air electrode 12 is obtained.
  • the firing conditions such as the firing temperature may be appropriately determined according to the type of each material used for the fuel electrode 11 and the air electrode 12.
  • materials constituting the fuel electrode 11 and the air electrode 12 materials used for a known SOFC fuel electrode and air electrode can be used, respectively.
  • binders and solvents used in the preparation of the slurry for the fuel electrode 11 and the air electrode 12 and binders and solvents known in the SOFC fuel electrode and air electrode manufacturing methods are known. Can be selected as appropriate.
  • the electrolyte-supporting cell 1 of the present embodiment is a solid-state electrolyte sheet for SOFC that can suppress a decrease in oxygen ion conductivity even when exposed to an atmosphere containing a sulfur component. It is provided as an electrolyte layer. Therefore, the electrolyte-supporting cell 1 of the present embodiment can suppress a decrease in durability even when fuel containing a sulfur component is supplied to the fuel electrode.
  • the single cell for SOFC of the present embodiment includes a fuel electrode, an air electrode, and a solid electrolyte layer disposed between the fuel electrode and the air electrode. At least one selected from the fuel electrode, the air electrode, and the solid electrolyte layer, It is stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ), and is rare earth oxide (hereinafter referred to as rare earth oxide C) of 0.003 mol% or more and less than 0.5 mol%.
  • rare earth oxide C is an oxide of at least one element selected from rare earth elements excluding Sc and Ce Is, Or Zirconia-based oxide stabilized with scandium oxide (Sc 2 O 3 ) and containing rare earth oxide (hereinafter sometimes referred to as rare earth oxide D) in an amount of 0.003 mol% to less than 0.5 mol% (Scandia-stabilized zirconia-based oxide) as an electrolyte component, and the rare earth oxide D is an oxide of at least one element selected from rare earth elements excluding Sc.
  • 0.003 mol% or more and less than 0.5 mol% rare earth oxide C means that the total amount of rare earth oxide C is 0.003 mol% or more and less than 0.5 mol%. means.
  • 0.003 mol% or more and less than 0.5 mol% rare earth oxide D means that the total amount of rare earth oxide D is 0.003 mol% or more and less than 0.5 mol%. . The same applies to the subsequent steps.
  • the SOFC single cell of this embodiment is made of zirconia in which at least one selected from the fuel electrode, the air electrode, and the solid electrolyte layer is stabilized with scandium oxide (Sc 2 O 3 ) as an electrolyte component. It contains a zirconia-based oxide (scandia-stabilized zirconia-based oxide) to which a trace amount of rare-earth oxide of 0.003 mol% or more and less than 0.5 mol% is added.
  • cerium oxide (CeO 2 ) added as an oxide is 0.5 mol% or more
  • cerium oxide (CeO 2 ) functions as a zirconia stabilizer
  • other rare earth elements other than Ce Zirconia-based oxides scandiaceria-stabilized zirconia-based oxides
  • scandiaceria-stabilized zirconia-based oxides added in an amount of 0.003 mol% or more and less than 0.5 mol%
  • zirconia-based oxide (the scandiaceria-stabilized zirconia-based oxide and the scandia-stabilized zirconia-based oxide) may be referred to as “zirconia-based oxide of this embodiment”.
  • the solid electrolyte layer contains the zirconia-based oxide of the present embodiment
  • the solid electrolyte layer can suppress a decrease in oxygen ion conductivity even when it is exposed to an atmosphere containing a sulfur component. Therefore, the SOFC single cell provided with such a solid electrolyte layer is a case where hydrogen generated by reforming city gas is used as a fuel, and the fuel may contain a sulfur component. Even in some cases, the decrease in durability can be kept small.
  • a desulfurization device is often provided along with the reformer.
  • the configuration of the single cell for SOFC of the present embodiment has an excellent effect particularly when applied to an internal reforming SOFC.
  • the zirconia-based oxide of the present embodiment may be included in the fuel electrode and / or the air electrode as part of the electrode composition.
  • the fuel electrode generally includes a conductive component for imparting conductivity and an electrolyte component as a skeleton component as main constituent materials. Therefore, even when a fuel containing a sulfur component is supplied to the fuel electrode by including the zirconia-based oxide of the present embodiment as an electrolyte component in the fuel electrode, the electrolyte component and the sulfur component in the fuel electrode The formation of this compound and the deposition and adhesion of sulfur components on the electrolyte surface are suppressed.
  • the SOFC single cell of the present embodiment includes the scandiaceria-stabilized zirconia-based oxide as an electrolyte component in at least one selected from a fuel electrode, an air electrode, and a solid electrolyte layer (form) 3-A) and a form (form 3-B) in which at least one selected from a fuel electrode, an air electrode, and a solid electrolyte layer contains the scandia-stabilized zirconia-based oxide as an electrolyte component, respectively explain.
  • the zirconia-based oxide contained as an electrolyte component in at least one selected from the fuel electrode, the air electrode, and the solid electrolyte layer is scandium oxide (Sc 2 O 3 ) and
  • the rare earth oxide C is stabilized with cerium oxide (CeO 2 ) and contains 0.003 mol% or more and less than 0.5 mol%.
  • the rare earth oxide C is an oxide of at least one element selected from rare earth elements excluding Sc and Ce.
  • the rare earth oxide C is at least one selected from the group consisting of Y, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. It is an oxide of an element.
  • an electrolyte component contained as a main component in the solid electrolyte layer may be composed of this zirconia-based oxide.
  • the solid electrolyte layer is zirconia in which 0.003 mol% or more and less than 0.5 mol% of rare earth oxide C is further solid-dissolved in zirconia in which scandium oxide and cerium oxide are dissolved as stabilizers.
  • the total amount of rare earth oxide C in the zirconia-based oxide is preferably 0.005 mol% to 0.4 mol%, and more preferably 0.01 mol% to 0.3 mol%.
  • the decrease in the conductivity of the solid electrolyte layer that occurs in an atmosphere containing a sulfur component causes the electrolyte component to form a compound with the sulfur component, or the sulfur component to deposit and adhere to the electrolyte surface. It is thought that it happens by doing.
  • rare earth oxide C contained in a trace amount within a range of 0.003 mol% to less than 0.5 mol% Has the effect of suppressing the formation of a compound of an electrolyte component and a sulfur component, deposition and adhesion of the sulfur component to the electrolyte surface, and the like.
  • the content of the rare earth oxide C is less than 0.003 mol%, the effect of suppressing the adverse effect of the sulfur component due to the rare earth oxide C on the electrolyte component is not sufficiently exhibited, and the atmosphere in which the solid electrolyte layer contains the sulfur component When exposed to oxygen, it is difficult to keep the oxygen ion conductivity change with time small.
  • the content of the rare earth oxide C is 0.5 mol% or more, it is expected that the sulfur component easily deposits and adheres to the surface of the electrolyte or reacts easily with the electrolyte component. As a result, as the inflow of fuel proceeds, the conductivity of the solid electrolyte layer gradually deteriorates. Accordingly, when the zirconia-based oxide constituting the electrolyte component contains the rare earth oxide C excessively, the change with time of the conductivity of the solid electrolyte layer becomes large.
  • the rare earth oxide C contained as a trace component is selected from the group consisting of Y, La, Pr, Nd, Sm, Gd, and Yb in order to more reliably suppress the temporal change in oxygen ion conductivity caused by the sulfur component. It is preferably an oxide of at least one element selected from the group consisting of Y, Sm, Gd, and Yb, and more preferably an oxide of at least one element selected from the group consisting of Y, Sm, Gd, and Yb.
  • the rare earth oxide C is gadolinium oxide (Gd 2 O 3 ).
  • gadolinium oxide (Gd 2 O 3 ) is contained in the zirconia-based oxide in Form 3-A as rare earth oxide C, among other rare earth oxides, formation of a compound of an electrolyte component and a sulfur component, Highly effective in suppressing the deposition and adhesion of sulfur components to the electrolyte surface. Therefore, when the zirconia-based oxide in Form 3-A contains gadolinium oxide (Gd 2 O 3 ) as the rare earth oxide C, the change over time in the oxygen ion conductivity caused by the sulfur component can be more reliably suppressed. Can do.
  • the zirconia-based oxide in Form 3-A contains gadolinium oxide (Gd 2 O 3 ), the content is preferably 0.003 mol% or more and 0.2 mol% or less. This is because when the content of gadolinium oxide (Gd 2 O 3 ) exceeds 0.2 mol%, the effect cannot be enhanced to the extent that it matches the content of gadolinium oxide (Gd 2 O 3 ).
  • the zirconia-based oxide in Form 3-A contains gadolinium oxide (Gd 2 O 3 ), it is preferable that yttrium oxide (Y 2 O 3 ) is further added as rare earth oxide C.
  • the sulfur component is an electrolyte. The effect of suppressing adverse effects on the components can be further improved.
  • the content of yttrium oxide (Y 2 O 3 ) is 0.003. A particularly excellent effect can be obtained when the content is in the range of from mol% to 0.2 mol%.
  • the zirconia-based oxide in Form 3-A preferably contains scandium oxide (Sc 2 O 3 ) in an amount of 8 mol% to 15 mol%, and contains 8.5 mol% to 12 mol%. It is more preferable that it is contained in an amount of 9 mol% or more and 11 mol% or less.
  • Sc 2 O 3 scandium oxide
  • the zirconia-based oxide in Form 3-A preferably contains cerium oxide (CeO 2 ) in an amount of 0.5 mol% to 2.5 mol%, preferably 0.6 mol% to 2 mol%. It is more preferable that it is contained in an amount of 0.7 mol% or more and 1.5 mol% or less.
  • CeO 2 cerium oxide
  • the zirconia-based oxide in Form 3-A may be included in the fuel electrode and / or the air electrode as part of the electrode composition.
  • the effects obtained when this zirconia-based oxide is contained in the fuel electrode and / or the air electrode are as described above.
  • the zirconia-based oxide contained as an electrolyte component in at least one selected from the fuel electrode, the air electrode, and the solid electrolyte layer is scandium oxide (Sc 2 O 3 ). It is stabilized and is composed of a zirconia-based oxide containing rare earth oxide D of 0.003 mol% or more and less than 0.5 mol%.
  • the rare earth oxide D is an oxide of at least one element selected from rare earth elements excluding Sc.
  • the rare earth oxide D is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. It is an oxide of a seed element.
  • an electrolyte component contained as a main component in the solid electrolyte layer may be composed of this zirconia-based oxide.
  • the solid electrolyte layer is a zirconia oxide in which 0.003 mol% or more and less than 0.5 mol% of rare earth oxide D is further dissolved in zirconia in which scandium oxide is dissolved as a stabilizer.
  • the sintered body may be formed.
  • the total amount of rare earth oxide D in the zirconia-based oxide is preferably 0.005 mol% or more and 0.4 mol% or less, and more preferably 0.01 mol% or more and 0.3 mol% or less.
  • the decrease in the conductivity of the solid electrolyte layer that occurs in an atmosphere containing a sulfur component occurs due to the electrolyte component forming a compound with the sulfur component, or the sulfur component being deposited or adhered to the electrolyte surface.
  • the rare earth oxide D contained in a trace amount within the range of 0.003 mol% or more and less than 0.5 mol% includes an electrolyte component and a sulfur component. It has the effect of suppressing the formation of the compound and the deposition and adhesion of sulfur components to the electrolyte surface.
  • the content of the rare earth oxide D is less than 0.003 mol%, the effect of suppressing the adverse effect of the sulfur component due to the rare earth oxide D on the electrolyte component is not sufficiently exhibited, and the atmosphere in which the solid electrolyte layer contains the sulfur component When exposed to oxygen, it is difficult to keep the oxygen ion conductivity change with time small.
  • the content of the rare earth oxide D is 0.5 mol% or more, it is expected that the sulfur component is likely to be deposited and adhered to the surface of the electrolyte, or to react with the electrolyte component. As a result, as the inflow of fuel proceeds, the conductivity of the solid electrolyte layer gradually deteriorates. Therefore, when the zirconia-based oxide constituting the electrolyte component contains the rare earth oxide D excessively, the change with time of the conductivity of the solid electrolyte layer becomes large.
  • the rare earth oxide D contained as a trace component is a group consisting of Y, La, Ce, Pr, Nd, Sm, Gd, and Yb in order to more reliably suppress the temporal change in oxygen ion conductivity caused by the sulfur component.
  • the oxide is an oxide of at least one element selected from the group consisting of Y, Ce, Sm, Gd, and Yb. More preferred.
  • the rare earth oxide D is cerium oxide (CeO 2 ).
  • cerium oxide (CeO 2 ) is contained as the rare earth oxide D in the zirconia-based oxide in Form 3-B, particularly among rare earth oxides, formation of a compound of an electrolyte component and a sulfur component, Highly effective in suppressing deposition and adhesion of sulfur components. Therefore, when the zirconia-based oxide in Form 3-B contains cerium oxide (CeO 2 ) as the rare earth oxide D, the change over time in the oxygen ion conductivity caused by the sulfur component can be more reliably suppressed. .
  • the zirconia-based oxide in Form 3-B contains cerium oxide (CeO 2 )
  • its content is preferably 0.1 mol% or more, and more preferably 0.2 mol% or more.
  • its content is preferably 0.48 mol% or less, and more preferably 0.45 mol% or less.
  • the zirconia-based oxide in Form 3-B when the rare earth oxide D is gadolinium oxide (Gd 2 O 3 ), a high effect of suppressing change with time in oxygen ion conductivity can be obtained.
  • the zirconia-based oxide in Form 3-B contains gadolinium oxide (Gd 2 O 3 )
  • its content is preferably 0.003 mol% or more and 0.2 mol% or less, and 0.005 mol% or more 0.1 mol% or less is more preferable.
  • the zirconia-based oxide in Form 3-B when the rare earth oxide D is yttrium oxide (Y 2 O 3 ), a high effect of suppressing change with time in oxygen ion conductivity can be obtained.
  • the zirconia-based oxide in Form 3-B contains yttrium oxide (Y 2 O 3 )
  • its content is preferably 0.003 mol% or more and 0.2 mol% or less, and 0.005 mol% or more 0.1 mol% or less is more preferable.
  • the zirconia-based oxide in Form 3-B may contain both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) as rare earth oxide D.
  • the electrolyte component of the solid electrolyte layer of Form 3-B is composed of a zirconia-based oxide containing both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) as rare earth oxide D. The effect of suppressing the adverse effect of the sulfur component on the electrolyte component can be further improved.
  • gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) are not clear, but gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O). 3 ) is preferably from 0.003 mol% to 0.2 mol%, more preferably from 0.005 mol% to 0.1 mol%.
  • the zirconia-based oxide in Form 3-B preferably contains scandium oxide (Sc 2 O 3 ) in an amount of 4 mol% to 15 mol%.
  • the zirconia-based oxide contains scandium oxide (Sc 2 O 3 ) in an amount of 4 mol% to 6.5 mol%. Is preferred.
  • the zirconia-based oxide preferably contains scandium oxide (Sc 2 O 3 ) in an amount of 9 mol% to 13 mol%. 9.5 mol% or more and 12 mol% or less, more preferably 10 mol% or more and 11.5 mol% or less.
  • the type of the SOFC single cell of the present embodiment refers to both the single cell for SOFC of form 3-A and the single cell for SOFC of form 3-B).
  • the configuration of the single cell for SOFC of this embodiment is an electrolyte support cell (hereinafter sometimes referred to as “ESC”) and a fuel electrode support cell (hereinafter sometimes referred to as “ASC”). It can be applied to any of an air electrode support cell (hereinafter sometimes referred to as “CSC”) and a metal support cell (hereinafter sometimes referred to as “MSC”).
  • ESC electrolyte support cell
  • ASC fuel electrode support cell
  • CSC air electrode support cell
  • MSC metal support cell
  • the single cell for SOFC of this embodiment is a fuel electrode support type cell
  • the SOFC single cell 2 of the present embodiment is disposed between the fuel electrode active layer (fuel electrode) 21, the air electrode 22, and the fuel electrode active layer 21 and the air electrode 22.
  • a solid electrolyte layer 23 and a fuel electrode support substrate 24 provided on the surface of the fuel electrode active layer 21 opposite to the solid electrolyte layer 23 and supporting the fuel electrode active layer 21, solid electrolyte layer 23, and air electrode 22.
  • the fuel electrode support substrate 24 and the fuel electrode active layer 21 are formed of a material containing a conductive component and a skeleton component.
  • the conductive component is a component for imparting conductivity to the fuel electrode support substrate 24 and the fuel electrode active layer 21.
  • the skeletal component is a component that forms the skeleton of the fuel electrode support substrate 24 and the fuel electrode active layer 21, and is an important component in securing necessary strength.
  • As the conductive component a known material used for the fuel electrode of the single cell for SOFC can be used. It is desirable that the skeletal component contains the zirconia-based oxide of this embodiment.
  • the skeleton component may be a combination of the zirconia-based oxide of this embodiment and another material known as a skeleton component of the fuel electrode.
  • the thickness of the fuel electrode active layer 21 is not particularly limited, but is preferably 5 ⁇ m or more, more preferably 7 ⁇ m or more, and further preferably 10 ⁇ m or more.
  • the thickness of the anode active layer 11 is preferably 100 ⁇ m or less, more preferably 50 ⁇ m or less, and further preferably 30 ⁇ m or less. If the thickness of the fuel electrode active layer 21 is within the above range, the electrode reaction is efficiently performed, and the power generation performance becomes better when the fuel electrode support cell is used.
  • the thickness of the fuel electrode support substrate 24 is not particularly limited, but is preferably, for example, 100 ⁇ m or more, more preferably 120 ⁇ m or more, and further preferably 150 ⁇ m or more. Further, the thickness of the fuel electrode support substrate 14 is preferably 3 mm or less, more preferably 2 mm or less, further preferably 1 mm or less, and particularly preferably 500 ⁇ m or less. If the thickness of the fuel electrode support substrate 34 is within the above range, the mechanical strength and gas permeability of the fuel electrode support substrate 24 can be easily balanced.
  • the solid electrolyte layer 23 desirably contains the zirconia-based oxide of the present embodiment.
  • the solid electrolyte layer 23 may be formed of the sintered body of the zirconia-based oxide of the present embodiment. That is, the electrolyte component contained in the solid electrolyte layer 23 may be made of the zirconia-based oxide of the present embodiment.
  • the solid electrolyte layer 23 may be a sintered body of a mixture of the zirconia-based oxide of the present embodiment and another material known as a material for the solid electrolyte layer for SOFC.
  • the electrolyte component contained in the solid electrolyte layer 23 may be a mixture of the zirconia-based oxide of this embodiment and another material known as a material for the solid electrolyte layer for SOFC.
  • the zirconia-based oxide of the present embodiment is desirably contained in an amount of 50% by mass or more, and more desirably 70% by mass or more.
  • the thickness of the solid electrolyte layer 23 is not particularly limited, but is preferably 3 ⁇ m or more, more preferably 4 ⁇ m or more, and further preferably 5 ⁇ m or more, for example. Further, the thickness of the solid electrolyte layer 23 is desirably 50 ⁇ m or less, more desirably 30 ⁇ m or less, and further desirably 20 ⁇ m or less. When the thickness of the solid electrolyte layer 23 is within the above range, when the fuel electrode support cell is used, the power generation performance is improved while preventing gas cross-leakage.
  • the air electrode 22 is generally made of a perovskite oxide that has excellent electron conductivity and is stable even in an oxidizing atmosphere. Specifically, La 0.8 Sr 0.2 MnO 3 , La 0.6 Sr 0.4 CoO 3 , La 0.6 Sr 0.4 FeO 3 and La 0.6 Sr 0.4 Co 0.2 Lanthanum manganite, lanthanum ferrite, lanthanum cobaltite, etc. in which a part of lanthanum such as Fe 0.8 O 3 is substituted with strontium are preferably used. Moreover, the air electrode 22 may contain the zirconia-type oxide of this embodiment.
  • the thickness of the air electrode 22 is not particularly limited, but is preferably 5 ⁇ m or more, more preferably 7 ⁇ m or more, and further preferably 10 ⁇ m or more. Further, the thickness of the air electrode 12 is desirably 80 ⁇ m or less, more desirably 70 ⁇ m or less, and further desirably 60 ⁇ m or less. When the thickness of the air electrode 22 is within the above range, the electrode reaction is efficiently performed, and the power generation performance is improved when the fuel electrode support cell is used. *
  • a raw material powder of the zirconia-based oxide of the present embodiment is prepared. Since this raw material powder can be manufactured using the same method as the raw material powder of the zirconia-based oxide contained in the electrolyte sheet of Embodiment 1, detailed description is omitted here.
  • An example of a method for manufacturing the single cell 2 for SOFC includes a step of producing a multilayer fired body including the fuel electrode support substrate 24, the fuel electrode active layer 21, and the solid electrolyte layer 23, and the obtained multilayer fired body is formed into a predetermined shape. And the step of producing the air electrode 22 on the surface opposite to the fuel electrode active layer 21 in the multilayer fired body cut into a predetermined shape.
  • the multilayer fired body (1) On a green sheet for the anode support substrate 24, a layer formed by screen printing for the anode active layer 21, a green layer such as a green sheet layer, and screen printing for the solid electrolyte layer 23, etc. A method of firing the whole or all at once after forming a laminate in which green layers such as formed layers and green sheet layers are sequentially stacked, Or (2) The green sheet for the fuel electrode support substrate 24 is fired to produce the fuel electrode support substrate 24, and the green layer for the fuel electrode active layer 21 and the green layer for the solid electrolyte layer 23 are sequentially formed thereon. A method of firing these after forming stacked laminates, Can be used.
  • the method for producing a multilayer fired body will be described by taking the method (1) as an example.
  • a green sheet for the fuel electrode support substrate 24 is prepared.
  • the green sheet for the fuel electrode support substrate 24 is a mixture of raw material powder (conductive component powder and skeletal component powder), a binder and a solvent, and further, if necessary, a pore forming agent, a dispersing agent, a plasticizer and the like.
  • the materials that can be used as the conductive component and the skeleton component are as described above.
  • the pore-forming agent, binder, solvent, dispersant, plasticizer, and the like can be selected from pore-forming agents, binders, solvents, dispersants, plasticizers, and the like that are known in the manufacturing method of the SOFC fuel electrode support substrate. It can be selected as appropriate.
  • the green layer for the fuel electrode active layer 21 is formed on the green sheet for the fuel electrode support substrate 24 using the paste for the fuel electrode active layer 21.
  • the paste for the anode active layer 21 is a mixture of raw material powder (conductive component powder and skeletal component powder), a binder and a solvent, and further, a pore forming agent, a dispersing agent, a plasticizer and the like are added as necessary. To be prepared. This paste is applied on a green sheet for the fuel electrode support substrate 24 by using a method such as screen printing, and dried to form a green layer for the fuel electrode active layer 21.
  • the materials that can be used as the conductive component and the skeleton component are as described above.
  • the pore-forming agent, binder, solvent, dispersant, plasticizer, etc. are selected from among pore-forming agents, binders, solvents, dispersants, plasticizers, etc. known in the SOFC fuel electrode active layer manufacturing method. It can be selected as appropriate.
  • the green layer for the solid electrolyte layer 23 is formed on the green layer for the fuel electrode active layer 21 using the paste for the solid electrolyte layer 23.
  • the paste for the solid electrolyte layer 23 is prepared by mixing at least a powder that is a raw material for the electrolyte component and a solvent.
  • the materials that can be used as the electrolyte component are as described above.
  • As the solvent used for the paste for the solid electrolyte layer 23 a known material used in preparing a solid electrolyte layer paste of SOFC can be used.
  • a binder, a dispersant, a plasticizer, a surfactant, an antifoaming agent, and the like may be added to the paste for the solid electrolyte layer 23 in addition to the powder and solvent that are the raw materials for the electrolyte component.
  • Binders, dispersants, plasticizers, surfactants, antifoaming agents, etc. are among the binders, dispersants, plasticizers, surfactants, antifoaming agents, etc. known in the SOFC solid electrolyte layer manufacturing method. Can be selected as appropriate.
  • a green layer for a barrier layer may be formed on the green layer for the solid electrolyte layer 23.
  • the green layer for the barrier layer is prepared by preparing a paste containing the raw material powder constituting the barrier layer and applying it to the green layer for the solid electrolyte layer 23. It can be formed by drying.
  • Laminates formed by sequentially stacking are fired collectively or sequentially.
  • the firing temperature of the laminate is not particularly limited, but is preferably 1100 ° C. or higher, more preferably 1200 ° C. or higher, and further preferably 1250 ° C. or higher.
  • the firing temperature is preferably 1500 ° C. or lower, more preferably 1400 ° C. or lower, and further preferably 1350 ° C. or lower.
  • the firing time during firing is not particularly limited, but is preferably 0.1 hours or longer, more preferably 0.5 hours or longer, and even more preferably 1 hour or longer.
  • the firing time is preferably 10 hours or less, more preferably 7 hours or less, and even more preferably 5 hours or less.
  • a multilayer fired body is obtained by the method as described above. Next, the obtained multilayer fired body is cut and / or punched into a predetermined shape.
  • the air electrode 22 is produced on the surface opposite to the fuel electrode support substrate 24.
  • a green layer for the air electrode 22 is formed using the paste for the air electrode 22, and the air electrode 22 is produced by firing the green layer.
  • the paste for the air electrode 22 is prepared by uniformly mixing together the raw material powder, the binder, and the solvent that constitute the air electrode 22 and, if necessary, the dispersant, the plasticizer, and the like.
  • the materials that can be used as the material constituting the air electrode 22 are as described above.
  • the binder, solvent, dispersant, plasticizer, and the like can be appropriately selected from binders, solvents, dispersants, plasticizers, and the like that are known in the SOFC air electrode manufacturing method.
  • the prepared paste is applied on the multilayer fired body by screen printing or the like and dried to form a green layer for the air electrode 22. By baking this, the air electrode 22 is produced.
  • a calcination temperature is not specifically limited, 800 degreeC or more is desirable, 850 degreeC or more is more desirable, and 950 degreeC or more is still more desirable.
  • the firing temperature is preferably 1400 ° C. or lower, more preferably 1350 ° C. or lower, and further preferably 1300 ° C. or lower.
  • the firing time during firing is not particularly limited, but is preferably 0.1 hours or longer, more preferably 0.5 hours or longer, and even more preferably 1 hour or longer.
  • the firing time is preferably 10 hours or less, more preferably 7 hours or less, and even more preferably 5 hours or less.
  • the SOFC single cell 2 can be manufactured by the method as described above.
  • the fuel electrode support type cell has been described as an example. However, even in the case of an electrolyte support type cell, an air electrode support type cell, and a metal support type cell, the zirconia-based oxidation of the present embodiment is similarly applied. It is possible to use the object for the fuel electrode, the air electrode and / or the solid electrolyte layer.
  • the SOFC of this embodiment includes the electrolyte-supported cell described in Embodiment 2 or the SOFC single cell described in Embodiment 3.
  • the SOFC of this embodiment includes, for example, a plurality of single cells that are stacked and connected in series (stacked). At this time, the adjacent single cells are electrically connected to each other, and at the same time, the fuel gas and the oxidant gas are properly distributed to the fuel electrode and the air electrode through the manifold, respectively.
  • a separator is arranged. The separator is also called an interconnector.
  • the single cell used in the SOFC of the present embodiment is less likely to be deteriorated in durability even when exposed to an atmosphere containing a sulfur component. Therefore, the durability of the SOFC of the present embodiment is not easily lowered even when exposed to an atmosphere containing a sulfur component.
  • the SOFC of the present embodiment is a case where hydrogen generated by reforming city gas is used as a fuel, and even if the fuel may contain a sulfur component, A decrease in durability can be kept small.
  • a desulfurization device is often provided along with the reformer.
  • the configuration of the SOFC of the present embodiment has an excellent effect particularly when an internal reforming SOFC is used.
  • xSc yCe zGd SZ refers to x mol% scandium oxide (Sc 2 O 3 ), y mol% cerium oxide (CeO 2 ), and z mol% gadolinium oxide ( Gd 2 O 3 ) and the remaining zirconium oxide (ZrO 2 ) means stabilized zirconia.
  • a neutralization coprecipitation reaction was carried out while finely adjusting the liquid speed of the mixed aqueous solution and aqueous ammonia so that the pH was in the range of 8.5 ⁇ 0.2 during the reaction.
  • the hydroxide in the effluent was separated from the mother liquor by filtration and then the ammonium chloride was removed by repeated washing with water.
  • the obtained hydroxide was dispersed in n-butanol and dehydrated by performing atmospheric distillation until the solution temperature reached 105 ° C.
  • the n-butanol dispersion containing the dehydrated hydroxide was spray-dried to obtain a powder with good fluidity. This powder was fired at 1000 ° C. for 1 hour to obtain a 10Sc1Ce0.1Gd0.05YSZ powder (sample 1 in Table 1) having a specific surface area of 9 m 2 / g and no agglomerates.
  • a predetermined amount of zirconium oxychloride, scandium chloride, cerium chloride, and a rare earth oxide were prepared so as to have the compositions of Samples 2 to 16 shown in Table 1.
  • the zirconia-based oxide powders of Samples 17 to 31 have a predetermined amount of zirconium oxychloride, scandium chloride, and a trace amount of rare earth oxide so as to have the compositions of Samples 17 to 31 shown in Table 2.
  • Al 2 O 3 , SiO 2 , TiO 2 , Fe 2 O 3 , Na 2 O, CaO 2 and Cl are also detected as impurities.
  • the amount of SiO 2 is in the zirconia powder. 0.005 mass% for less impurities excluding SiO 2 was 0.001 mass% as trace amount, respectively.
  • the composition calculation method of each zirconia-based oxide powder will be described below.
  • the obtained slurry was transferred to a jacketed round bottom cylindrical vacuum degassing vessel having an internal volume of 50 L equipped with a bowl-shaped stirrer, and the jacket temperature was adjusted to 40 ° C. while rotating the stirrer at a speed of 30 rpm.
  • the slurry was concentrated and degassed under a pressure of ⁇ 21 kPa, and the viscosity at 25 ° C. was adjusted to 3 Pa ⁇ s to obtain a slurry for coating.
  • This coating slurry was continuously coated on a polyethylene terephthalate (PET) film by a doctor blade method.
  • PET polyethylene terephthalate
  • a long green tape was obtained by drying at 40 ° C., 80 ° C., and 110 ° C. This green tape was cut into a circular shape of about 38 mm ⁇ with a punching blade (manufactured by Nakayama Paper Equipment Co., Ltd.) and further peeled from the PET film to prepare each zirconia green sheet
  • a fuel electrode paste containing 65 parts by mass and 35 parts by mass of commercially available 8YSZ-based powder (manufactured by Daiichi Rare Element Co., Ltd., HSY-8.0) was applied by screen printing and dried. I let you.
  • each electrolyte sheet On the other side of each electrolyte sheet, a commercially available strontium-doped lanthanum manganese composite oxide powder (manufactured by AGC Seimi Chemical Co., Ltd .: La 0.6 An air electrode paste containing 80 parts by mass of Sr 0.4 MnO 3 ) and 20 parts by mass of a commercially available 20 mol% gadolinia dope ceria powder (manufactured by AGC Seimi Chemical Co., Ltd .: GDC20) was applied by screen printing and dried. Next, each electrolyte sheet coated with electrodes on both sides was baked at 1300 ° C. for 3 hours to form a 30-mm ⁇ 30-mm ⁇ three-layer structure in which a fuel electrode layer having a thickness of 40 ⁇ m and an air electrode layer having a thickness of 30 ⁇ m were formed. Each ESC shown in Tables 3 and 4 was prepared.
  • a slurry was prepared. This slurry is put in a vacuum degassing machine, and the vertical stirring blade immersed in the slurry is concentrated and degassed while rotating at a rotation speed of 10 rpm for 24 hours, and the viscosity at 25 ° C. is adjusted to 8 Pa ⁇ s.
  • a slurry for coating was obtained. This coating slurry was continuously applied onto a PET film by a doctor blade method, and then dried at 40 ° C., 80 ° C., and 110 ° C. to obtain a long green tape. This green tape was cut to about 38 mm ⁇ with a punching blade, and further peeled from the PET film to produce a 3YSZ / NiO green sheet.
  • This green sheet is sandwiched between 99.5% nickel aluminate porous plates (porosity: 30%) with a maximum ridge height of 10 ⁇ m so that the peripheral edge of the green sheets does not protrude, and a shelf plate with a thickness of 20 mm (
  • the product was placed on a product name “Dialite DC-M” manufactured by Tokai Koetsu Kogyo Co., Ltd. and fired at 1350 ° C.
  • a fuel electrode support substrate having a circular shape of 30 mm ⁇ and a thickness of 0.5 mm was produced.
  • the fuel electrode paste used in (5) (i) above was applied to the obtained fuel electrode support substrate by screen printing except for the 3 mm wide periphery from the periphery of the fuel electrode support substrate, dried, and then 1300 A fuel electrode supporting substrate with a fuel electrode active layer was produced by firing at 0 ° C.
  • Each slurry for electrolyte membrane was apply
  • 10Sc1CeSZ powders (samples 15 and 16)) obtained in step 1) were formed to a thickness of 5 ⁇ m to form an electrolyte layer, on which a commercially available strontium-doped lanthanum iron cobalt complex oxide was formed.
  • An air electrode layer was formed by laminating powder of (La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 ) to a thickness of 30 ⁇ m by thermal spraying, and two types of MSCs shown in Table 6 were formed. Produced.
  • the obtained strip-shaped electrolyte sheet was used as a test piece, and in an electric furnace maintained at 800 ° C., air containing 10 ppm of tertiary butyl mercaptan (sulfur compound) (hereinafter, sulfur component-containing air) was circulated for 100 hours. Thereafter, the oxygen ion conductivity of the test piece was measured after 1000 hours and 2000 hours, and for Samples 1, 2, 15, 20, 28, and 31 after 3000 hours had elapsed.
  • sulfur compound sulfur compound
  • gold wires 32 a to 32 d having a diameter of 0.2 mm are wound around 4 pieces at 1 cm intervals around a test piece 31, coated with gold paste, dried and fixed at 100 ° C.
  • a current / voltage terminal is used, and both ends of the test piece 31 wound with the gold wires 32a and 32d are sandwiched between alumina plates 33 so that the gold wires 32a and 32d are in close contact with the test piece 31, and a load 34 of about 500 g is applied from above.
  • the temperature is kept at 800 ° C., a constant current of 0.1 mA is applied to the outer two terminals (gold wires 32a and 32d), and the voltage of the inner two terminals (gold wires 32b and 32c) is changed to a digital multimeter (Advantest). (Trade name “TR6845 type”) (not shown) was used, and the measurement was performed by the direct current four-terminal method. Also, a gold wire was used for a lead wire (not shown).
  • test piece was disposed so as to be located at the center of the glass tube placed on the tubular electric furnace. By continuously circulating the sulfur component-containing air from one end of the glass tube to the other, the test piece was always exposed to the sulfur component-containing air.
  • Tables 1 and 2 show the results of the decrease rate of the conductivity of each electrolyte sheet.
  • the result of the rate of decrease in conductivity for the electrolyte sheet of Sample 16 was prepared using the same green sheet as Sample 15 as a reference example for confirming that the conductivity is decreased by the sulfur component-containing air. It is a result at the time of changing the air which a test piece is exposed in the said evaluation test method from the sulfur component containing air to the air which does not contain a sulfur component using a test piece.
  • the rate of decrease in conductivity after 100 hours is 2% or more in the 10Sc1Ce1AlSZ electrolyte sheet (sample 14) and the 9Sc1AlSZ electrolyte sheet (sample 30), but in other electrolyte sheets, A large difference was not confirmed at 1.7% or less.
  • the electrolyte sheet satisfying the requirements of the electrolyte sheet of the present invention that is, stabilized with Sc 2 O 3 and CeO 2 shown in Table 1, and 0.003 mol% or more and 0.5
  • An electrolyte sheet composed of zirconia-based oxides containing less than mol% rare earth oxide A electrolyte sheets of Examples 1 to 11 (Examples)
  • Sc 2 O 3 shown in Table 2
  • the decrease rate was less than 8%
  • the decrease rate of the conductivity of the electrolyte sheets (Comparative Examples) of Samples 12 to 15 and 28 to 31 that did not satisfy the requirements of the electrolyte sheet of the present invention was Less than 8% It was on.
  • the electrolyte sheet satisfying the requirements of the electrolyte sheet of the present invention has a small decrease in conductivity after 2000 hours, and further has a larger difference in decrease in conductivity after 3000 hours. From this result, it was confirmed that the electrolyte sheet of the present invention has a small change with time in the oxygen ion conductivity in an atmosphere containing a sulfur component.
  • 41 is an electric furnace
  • 42 is a zirconia outer tube
  • 43 is a zirconia inner tube
  • 44 is a gold lead wire
  • 45 is a solid electrolyte layer
  • 46 is a sealing material
  • 48 is an air electrode
  • 47 is a fuel. Show poles.
  • the operating temperature was 850 ° C.
  • the operating temperature was 750 ° C.
  • the operating temperature was 700 ° C.
  • the product name “TR6845” manufactured by Advantest Corporation was used as the voltage measuring device
  • the product name “GPO16-20R” manufactured by Takasago Seisakusho was used as the current voltage generator.
  • a constant current of 0.3 A / cm 2 was applied to the fuel electrode side under a flow of 1 liter / min of hydrogen containing 10 ppm of tertiary butyl mercaptan as a fuel gas and air as an oxidant on the air electrode side. While driving.
  • Table 3 shows the rate of decrease in power generation characteristics of ESCs (ESC-1 to ESC-7 (Examples)) in which electrolyte sheets composed of zirconia-based oxides including rare earth oxide A are used. Thus, even after 2000 hours, it was less than 14%.
  • the rate of decrease in power generation characteristics was 16% or more. The difference in the rate of decrease in power generation characteristics between cells that satisfy the requirements of the single cell of the present invention and cells that do not satisfy the requirement became larger after 3000 hours, and the rate of decrease in power generation characteristics reached 5% or more.
  • a cell satisfying the requirements of the single cell of the present invention shown in Table 4, that is, a rare earth oxide of 0.003 mol% or more and less than 0.5 mol% that is stabilized with Sc 2 O 3 in the solid electrolyte layer ESCs (ESC-11 to ESC-17 (examples)) in which an electrolyte sheet composed of a zirconia-based oxide containing B is used are shown in Table 4. Even after 2000 hours, it was less than 15%. In contrast, in ESC-19 and ESC20 (comparative examples) that do not satisfy the requirements of the single cell of the present invention, the rate of decrease in power generation characteristics was 15% or more. In ESC-18, the rate of decrease in power generation characteristics after 2000 hours is kept low.
  • the ESC using the electrolyte sheet of the present invention that is, the electrolyte-supported cell of the present invention, suppresses the rate of decrease in power generation characteristics. I understand that.
  • the rate of decrease in the power generation characteristics of the ASC shown in Table 5 and the MSC shown in Table 6 is also the difference in the rate of decrease in the power generation characteristics between the cells that satisfy the requirements of the single cell of the present invention and the cells that do not satisfy the requirements. It became 5% or more.
  • the single cell of the present invention exhibits excellent durability in a sulfur component-containing atmosphere.
  • the SOFC electrolyte sheet of the present invention can suppress a decrease in durability even when a fuel containing a sulfur compound such as city gas is used. Therefore, the electrolyte sheet for SOFC of the present invention can be suitably used as an electrolyte layer for household SOFC that uses city gas or the like as fuel.
  • the SOFC single cell and SOFC of the present invention can be used as a SOFC that uses city gas or the like as the fuel, for example, because it can suppress a decrease in durability even when the fuel contains a sulfur compound.

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Abstract

This electrolyte sheet for a solid oxide fuel cell contains an electrolyte component. The electrolyte component is configured from a zirconia-based oxide stabilized by scandium oxide (Sc2O3) and cerium oxide (CeO2) and containing at least 0.003 mol% and less than 0.5 mol% of a rare earth oxide (the oxide of at least one element selected from the rare earth elements excluding Sc and Ce), or is configured from a zirconia-based oxide stabilized by scandium oxide (Sc2O3) and containing at least 0.003 mol% and less than 0.5 mol% of a rare earth oxide (the oxide of at least one element selected from the rare earth elements excluding Sc).

Description

固体酸化物形燃料電池用電解質シート、電解質支持型セル、固体酸化物形燃料電池用単セル及び固体酸化物形燃料電池Electrolyte sheet for solid oxide fuel cell, electrolyte supporting cell, single cell for solid oxide fuel cell, and solid oxide fuel cell
　本発明は、固体酸化物形燃料電池用電解質シートと、それを用いた電解質支持型セルと、固体酸化物形燃料電池用単セルと、前記電解質支持型セル又は前記固体酸化物形燃料電池用単セルを備えた固体酸化物形燃料電池とに関する。 The present invention relates to an electrolyte sheet for a solid oxide fuel cell, an electrolyte supporting cell using the same, a single cell for a solid oxide fuel cell, and the electrolyte supporting cell or the solid oxide fuel cell. The present invention relates to a solid oxide fuel cell including a single cell.
　近年、燃料電池は、クリーンエネルギー源として注目されている。燃料電池のうち、電解質に固体のセラミックを使用している固体酸化物形燃料電池（以下、「ＳＯＦＣ」と記載する。）は、作動温度が高いため排熱を利用でき、さらに高効率で電力を得ることができる等の長所を有しており、家庭用電源から大規模発電まで幅広い分野での活用が期待されている。 In recent years, fuel cells have attracted attention as a clean energy source. Among the fuel cells, solid oxide fuel cells (hereinafter referred to as “SOFC”) that use solid ceramics as the electrolyte can utilize exhaust heat because of their high operating temperature, and are more efficient and power efficient. It is expected to be used in a wide range of fields from household power sources to large-scale power generation.
　ＳＯＦＣは、基本構造として、空気極と燃料極との間にセラミックからなる固体電解質層が配置された構造を有する。ＳＯＦＣでは、空気極に導入された空気中の酸素が電子を受け取って酸素イオン（Ｏ２－）となり、この酸素イオンが固体電解質層中を移動して燃料極へ到達する。燃料極に到達した酸素イオンが燃料極で水素と電気化学的に反応することによって電子が放出されて、電気出力が得られる。 The SOFC has a structure in which a solid electrolyte layer made of ceramic is disposed between an air electrode and a fuel electrode as a basic structure. In the SOFC, oxygen in the air introduced into the air electrode receives electrons and becomes oxygen ions (O 2− ), and the oxygen ions move through the solid electrolyte layer and reach the fuel electrode. Electrons are released when oxygen ions that have reached the fuel electrode react electrochemically with hydrogen at the fuel electrode, and an electrical output is obtained.
　このような発電メカニズムでは、固体電解質層には、酸素イオン導電性が高いこと及び材料強度が高いこと等の特性が要求される。したがって、固体電解質層には、一般的に、イットリア（Ｙ２Ｏ３）が添加されたジルコニア（イットリア安定化ジルコニア（ＹＳＺ））及びスカンジア（Ｓｃ２Ｏ３）が添加されたジルコニア（スカンジア安定化ジルコニア（ＳｃＳＺ））のようなジルコニア系酸化物等の焼結体が用いられている。例えば、特許文献１には、高い酸素イオン導電性及び高い材料強度に加え、安定した結晶相の実現も可能とする固体電解質層の材料が、種々提案されている。 In such a power generation mechanism, the solid electrolyte layer is required to have characteristics such as high oxygen ion conductivity and high material strength. Therefore, the solid electrolyte layer generally includes zirconia (yttria stabilized zirconia (YSZ)) to which yttria (Y 2 O 3 ) is added and zirconia (scandia stabilization to which scandia (Sc 2 O 3 ) is added). A sintered body such as a zirconia-based oxide such as zirconia (ScSZ) is used. For example, Patent Document 1 proposes various materials for a solid electrolyte layer that can realize a stable crystal phase in addition to high oxygen ion conductivity and high material strength.
特開２０００－３４０２４０号公報JP 2000-340240 A
　ＳＯＦＣの燃料極に供給される燃料としては、水素だけでなく、都市ガス（主成分：メタン）を改質することで生成した水素と一酸化炭素（ＣＯ）とを含む燃料も使用可能である。都市ガスを燃料に利用する場合、水素のみを燃料として用いる場合と比較して、ＳＯＦＣの耐久性が低下することが知られているが、本発明者らがさらに詳しく検討を進めたところ、ガス漏れ検知のために都市ガスに数ｐｐｍ程度含まれる付臭剤としての硫黄化合物が、ＳＯＦＣの固体電解質層や電極に含まれる電解質成分と反応するためか、あるいは電解質表面に沈着・付着するためにより、固体電解質層の酸素イオン導電性を低下させたり、電極の活性を低下させたりして、ＳＯＦＣの耐久性を低下させる大きな要因となっていることが見出された。 As fuel supplied to the SOFC fuel electrode, not only hydrogen but also fuel containing hydrogen and carbon monoxide (CO) generated by reforming city gas (main component: methane) can be used. . When city gas is used as fuel, it is known that the durability of SOFC will be lower than when only hydrogen is used as fuel. This is because sulfur compounds as odorants contained in city gas of several ppm for leak detection react with electrolyte components contained in SOFC solid electrolyte layers and electrodes, or because they deposit or adhere to the electrolyte surface. It has been found that the oxygen ion conductivity of the solid electrolyte layer is lowered and the activity of the electrode is lowered, which is a major factor for reducing the durability of the SOFC.
　そこで、本発明は、硫黄成分を含む雰囲気に曝される場合であっても、酸素イオン導電率の経時変化を小さく抑えることが可能なＳＯＦＣ用電解質シートを提供することを目的とする。さらに、本発明は、硫黄成分を含む燃料が燃料極に供給される場合であっても、耐久性の低下を小さく抑えることができる電解質支持型セル、ＳＯＦＣ用単セル及びＳＯＦＣを提供することも目的とする。 Therefore, an object of the present invention is to provide an SOFC electrolyte sheet that can suppress a change with time in oxygen ion conductivity even when exposed to an atmosphere containing a sulfur component. Furthermore, the present invention also provides an electrolyte-supported cell, a single cell for SOFC, and a SOFC that can suppress a decrease in durability even when fuel containing a sulfur component is supplied to the fuel electrode. Objective.
　本発明の第１の態様は、
　電解質成分を含み、
　前記電解質成分が、酸化スカンジウム（Ｓｃ２Ｏ３）及び酸化セリウム（ＣｅＯ２）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物を含むジルコニア系酸化物で構成されており、
　前記希土類酸化物は、Ｓｃ及びＣｅを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である、
ＳＯＦＣ用電解質シートを提供する。 The first aspect of the present invention is:
Including electrolyte components,
The electrolyte component is a zirconia-based oxide that is stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ) and contains a rare earth oxide of 0.003 mol% or more and less than 0.5 mol%. Configured,
The rare earth oxide is an oxide of at least one element selected from rare earth elements excluding Sc and Ce.
An electrolyte sheet for SOFC is provided.
　本発明の第２の態様は、
　電解質成分を含み、
　前記電解質成分が、酸化スカンジウム（Ｓｃ２Ｏ３）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物を含むジルコニア系酸化物で構成されており、
　前記希土類酸化物は、Ｓｃを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である、
ＳＯＦＣ用電解質シートを提供する。 The second aspect of the present invention is:
Including electrolyte components,
The electrolyte component is composed of a zirconia-based oxide that is stabilized with scandium oxide (Sc 2 O 3 ) and contains a rare earth oxide of 0.003 mol% or more and less than 0.5 mol%,
The rare earth oxide is an oxide of at least one element selected from rare earth elements excluding Sc.
An electrolyte sheet for SOFC is provided.
　本発明の第３の態様は、
　燃料極と、空気極と、前記燃料極と前記空気極との間に配置された第１の態様又は第２の態様に係るＳＯＦＣ用電解質シートと、を備えた電解質支持型セルを提供する。 The third aspect of the present invention is:
Provided is an electrolyte-supporting cell comprising a fuel electrode, an air electrode, and the SOFC electrolyte sheet according to the first aspect or the second aspect disposed between the fuel electrode and the air electrode.
　本発明の第４の態様は、
　燃料極と、空気極と、前記燃料極と前記空気極との間に配置された固体電解質層とを備え、
　前記燃料極、前記空気極及び前記固体電解質層から選ばれる少なくとも何れか１つが、酸化スカンジウム（Ｓｃ２Ｏ３）及び酸化セリウム（ＣｅＯ２）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物を含むジルコニア系酸化物を電解質成分として含み、
　前記希土類酸化物は、Ｓｃ及びＣｅを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である、
ＳＯＦＣ用単セルを提供する。 The fourth aspect of the present invention is:
A fuel electrode, an air electrode, and a solid electrolyte layer disposed between the fuel electrode and the air electrode,
At least one selected from the fuel electrode, the air electrode, and the solid electrolyte layer is stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ), and is 0.003 mol% or more and 0 A zirconia-based oxide containing less than 5 mol% rare earth oxide as an electrolyte component;
The rare earth oxide is an oxide of at least one element selected from rare earth elements excluding Sc and Ce.
A single cell for SOFC is provided.
　本発明の第５の態様は、
　燃料極と、空気極と、前記燃料極と前記空気極との間に配置された固体電解質層とを備え、
　前記燃料極、前記空気極及び前記固体電解質層から選ばれる少なくとも何れか１つが、酸化スカンジウム（Ｓｃ２Ｏ３）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物を含むジルコニア系酸化物を電解質成分として含み、
　前記希土類酸化物は、Ｓｃを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である、
ＳＯＦＣ用単セルを提供する。 According to a fifth aspect of the present invention,
A fuel electrode, an air electrode, and a solid electrolyte layer disposed between the fuel electrode and the air electrode,
At least one selected from the fuel electrode, the air electrode, and the solid electrolyte layer is stabilized with scandium oxide (Sc 2 O 3 ), and the rare earth is not less than 0.003 mol% and less than 0.5 mol% A zirconia oxide containing oxide is included as an electrolyte component,
The rare earth oxide is an oxide of at least one element selected from rare earth elements excluding Sc.
A single cell for SOFC is provided.
　本発明の第６の態様は、
　第３の態様に係る電解質支持型セル、第４の態様に係るＳＯＦＣ用単セル、又は、第５の態様に係るＳＯＦＣ用単セルを備えた、ＳＯＦＣを提供する。 The sixth aspect of the present invention is:
An SOFC comprising the electrolyte-supporting cell according to the third aspect, the SOFC single cell according to the fourth aspect, or the SOFC single cell according to the fifth aspect is provided.
　本発明の第１の態様及び第２の態様に係るＳＯＦＣ用電解質シートは、硫黄成分を含む雰囲気に曝される場合であっても、酸素イオン導電率の経時変化を小さく抑えることができる。また、本発明の第３の態様に係る電解質支持型セルは、そのようなＳＯＦＣ用電解質シートを備えているので、硫黄成分を含む燃料が燃料極に供給される場合であっても、耐久性の低下を小さく抑えることができる。 The SOFC electrolyte sheet according to the first and second aspects of the present invention can suppress changes in oxygen ion conductivity over time even when exposed to an atmosphere containing a sulfur component. In addition, since the electrolyte supporting cell according to the third aspect of the present invention includes such an electrolyte sheet for SOFC, durability is ensured even when a fuel containing a sulfur component is supplied to the fuel electrode. Can be kept small.
　本発明の第４の態様及び第５の態様に係るＳＯＦＣ用単セルは、硫黄成分を含む雰囲気に曝される場合であっても、固体電解質層の酸素イオン導電性の経時変化、又は、電極の活性の経時変化を小さく抑えることができるので、耐久性の低下を小さく抑えることができる。 Even if the SOFC single cell according to the fourth and fifth aspects of the present invention is exposed to an atmosphere containing a sulfur component, the oxygen ion conductivity of the solid electrolyte layer changes with time, or the electrode. Since the change with time of the activity can be suppressed to a small level, it is possible to suppress a decrease in durability.
　本発明の第６の態様に係るＳＯＦＣは、第３の態様に係る電解質支持型セル、第４の態様に係るＳＯＦＣ用単セル又は第５の態様に係るＳＯＦＣ用単セルを備えているので、硫黄成分を含む雰囲気に曝される場合であっても、耐久性の低下を小さく抑えることができる。 Since the SOFC according to the sixth aspect of the present invention includes the electrolyte-supporting cell according to the third aspect, the SOFC single cell according to the fourth aspect, or the SOFC single cell according to the fifth aspect, Even when exposed to an atmosphere containing a sulfur component, a decrease in durability can be minimized.
本発明の電解質支持型セルの一実施形態を示す断面図である。It is sectional drawing which shows one Embodiment of the electrolyte support type | mold cell of this invention. 本発明のＳＯＦＣ用単セルの一実施形態を示す断面図である。It is sectional drawing which shows one Embodiment of the single cell for SOFC of this invention. 酸素イオン導電率の測定方法を説明する図である。It is a figure explaining the measuring method of oxygen ion conductivity. 実施例で用いられた、単セル発電評価装置を示す概念図である。It is a conceptual diagram which shows the single cell electric power generation evaluation apparatus used in the Example.
　（実施形態１）
　本発明のＳＯＦＣ用電解質シートの実施形態について、具体的に説明する。 (Embodiment 1)
The embodiment of the electrolyte sheet for SOFC of the present invention will be specifically described.
　本実施形態の電解質シートは、電解質成分を含んでおり、当該電解質成分が、
　酸化スカンジウム（Ｓｃ２Ｏ３）及び酸化セリウム（ＣｅＯ２）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物（以下、希土類酸化物Ａということがある。）を含むジルコニア系酸化物（スカンジアセリア安定化ジルコニア系酸化物）で構成されており、当該希土類酸化物ＡがＳｃ及びＣｅを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である、
又は、
　酸化スカンジウム（Ｓｃ２Ｏ３）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物（以下、希土類酸化物Ｂということがある。）を含むジルコニア系酸化物（スカンジア安定化ジルコニア系酸化物）で構成されており、当該希土類酸化物ＢがＳｃを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である。 The electrolyte sheet of the present embodiment includes an electrolyte component, and the electrolyte component is
It is stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ), and is rare earth oxide (hereinafter referred to as rare earth oxide A) of 0.003 mol% or more and less than 0.5 mol%. ) Containing at least one element selected from rare earth elements excluding Sc and Ce. Is,
Or
A zirconia-based oxide stabilized with scandium oxide (Sc 2 O 3 ) and containing a rare earth oxide (hereinafter sometimes referred to as rare earth oxide B) of 0.003 mol% or more and less than 0.5 mol% (Scandia-stabilized zirconia-based oxide), and the rare earth oxide B is an oxide of at least one element selected from rare earth elements excluding Sc.
　ここで、「０．００３モル％以上０．５モル％未満の希土類酸化物Ａ」とは、希土類酸化物Ａの合計量が０．００３モル％以上０．５モル％未満であるということを意味する。また、「０．００３モル％以上０．５モル％未満の希土類酸化物Ｂ」とは、希土類酸化物Ｂの合計量が０．００３モル％以上０．５モル％未満であることを意味する。以降についても、同様である。 Here, “0.003 mol% or more and less than 0.5 mol% rare earth oxide A” means that the total amount of rare earth oxide A is 0.003 mol% or more and less than 0.5 mol%. means. Further, “the rare earth oxide B of 0.003 mol% or more and less than 0.5 mol%” means that the total amount of the rare earth oxide B is 0.003 mol% or more and less than 0.5 mol%. . The same applies to the subsequent steps.
　換言すると、本実施形態の電解質シートは、電解質成分を含み、当該電解質成分が、酸化スカンジウム（Ｓｃ２Ｏ３）で安定化されたジルコニアに０．００３モル％以上０．５モル％未満の微量の希土類酸化物が添加されたジルコニア系酸化物（スカンジア安定化ジルコニア系酸化物）であること、また、スカンジア安定化ジルコニア系酸化物に希土類酸化物として添加される酸化セリウム（ＣｅＯ２）の含有量が０．５モル％以上となる場合は、酸化セリウム（ＣｅＯ２）はジルコニアの安定化剤として機能し、Ｃｅ以外の他の希土類元素の酸化物が０．００３モル％以上０．５モル％未満の範囲で添加されたジルコニア系酸化物（スカンジアセリア安定化ジルコニア系酸化物）であること、を特徴としている。 In other words, the electrolyte sheet of the present embodiment includes an electrolyte component, and the electrolyte component is a trace amount of 0.003 mol% or more and less than 0.5 mol% in zirconia stabilized with scandium oxide (Sc 2 O 3 ). A zirconia-based oxide (scandia-stabilized zirconia-based oxide) to which a rare-earth oxide is added, and cerium oxide (CeO 2 ) added to the scandia-stabilized zirconia-based oxide as a rare earth oxide When the amount is 0.5 mol% or more, cerium oxide (CeO 2 ) functions as a stabilizer for zirconia, and other rare earth element oxides other than Ce are 0.003 mol% or more and 0.5 mol%. It is characterized by being a zirconia-based oxide (scandiaceria-stabilized zirconia-based oxide) added in a range of less than%.
　以上のような構成を有する本実施形態の電解質シートは、硫黄成分を含む雰囲気に曝された場合であっても、酸素イオン導電率の低下を抑制できる。したがって、都市ガスを改質することで生成した水素が燃料として用いられる場合であって、しかもその燃料に硫黄成分が含まれる可能性がある場合であっても、本実施形態の電解質シートをＳＯＦＣの固体電解質層として好適に用いることができる。例えば、都市ガスを燃料に利用するＳＯＦＣシステムにおいて、燃料電池外に改質器を設けて都市ガスを改質するシステムの場合、改質器と共に脱硫装置も設けられる場合が多い。しかし、都市ガスをＳＯＦＣ内で直接改質する内部改質型のＳＯＦＣが用いられるシステムでは、脱硫装置が設けられない場合もある。したがって、本実施形態の電解質シートは、特に、内部改質型のＳＯＦＣの固体電解質層に適用された場合に、優れた効果を奏する。 The electrolyte sheet of the present embodiment having the above-described configuration can suppress a decrease in oxygen ion conductivity even when exposed to an atmosphere containing a sulfur component. Therefore, even when hydrogen generated by reforming city gas is used as a fuel and the fuel may contain a sulfur component, the electrolyte sheet of this embodiment is used as the SOFC. It can be suitably used as a solid electrolyte layer. For example, in an SOFC system that uses city gas as fuel, in a system that reforms city gas by providing a reformer outside the fuel cell, a desulfurization device is often provided along with the reformer. However, in a system in which an internal reforming SOFC that directly reforms city gas in the SOFC is used, a desulfurization apparatus may not be provided. Therefore, the electrolyte sheet of the present embodiment exhibits excellent effects particularly when applied to an internal reforming SOFC solid electrolyte layer.
　以下に、本実施形態の電解質シートに含まれる電解質成分が、上記スカンジアセリア安定化ジルコニア系酸化物である形態（形態１－Ａ）と、上記スカンジア安定化ジルコニア系酸化物である形態（形態１－Ｂ）とについて、それぞれ説明する。 In the following, the electrolyte component contained in the electrolyte sheet of the present embodiment is a form that is the scandiaceria-stabilized zirconia-based oxide (form 1-A) and a form that is the scandia-stabilized zirconia-based oxide (form 1). -B) will be described respectively.
　（形態１－Ａ（スカンジアセリア安定化ジルコニア系酸化物））
　形態１－Ａに係る電解質シートの主成分として含まれる電解質成分は、酸化スカンジウム（Ｓｃ２Ｏ３）及び酸化セリウム（ＣｅＯ２）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物Ａを含むジルコニア系酸化物で構成されている。当該希土類酸化物Ａは、Ｓｃ及びＣｅを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である。すなわち、希土類酸化物Ａは、Ｙ、Ｌａ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ及びＬｕからなる群から選択される少なくとも何れか１種の元素の酸化物である。例えば、形態１－Ａに係る電解質シートは、安定化剤として酸化スカンジウム及び酸化セリウムが固溶されたジルコニアに、０．００３モル％以上０．５モル％未満の希土類酸化物Ａがさらに固溶されているジルコニア系酸化物の焼結体によって形成されている。前記ジルコニア系酸化物における希土類酸化物Ａの合計量は、０．００５モル％以上０．４モル％以下が好ましく、０．０１モル％以上０．３モル％以下がより好ましい。 (Form 1-A (scandiaceria-stabilized zirconia oxide))
The electrolyte component contained as the main component of the electrolyte sheet according to Form 1-A is stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ), and is 0.003 mol% or more and 0.5 mol It is comprised with the zirconia-type oxide containing the rare earth oxide A of less than%. The rare earth oxide A is an oxide of at least one element selected from rare earth elements excluding Sc and Ce. That is, the rare earth oxide A is at least one selected from the group consisting of Y, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. It is an oxide of an element. For example, in the electrolyte sheet according to Form 1-A, 0.003 mol% or more and less than 0.5 mol% of rare earth oxide A is further dissolved in zirconia in which scandium oxide and cerium oxide are dissolved as stabilizers. The zirconia-based oxide sintered body is formed. The total amount of rare earth oxide A in the zirconia-based oxide is preferably 0.005 mol% or more and 0.4 mol% or less, and more preferably 0.01 mol% or more and 0.3 mol% or less.
　硫黄成分を含む雰囲気下で生じる電解質シートの導電率の低下は、電解質成分が硫黄成分と化合物を形成したり、硫黄成分が電解質表面へ沈着・付着したりすることなどによって起こると考えられる。酸化スカンジウム（Ｓｃ２Ｏ３）及び酸化セリウム（ＣｅＯ２）で安定化されたジルコニア系酸化物において、０．００３モル％以上０．５モル％未満の範囲内で微量に含まれる希土類酸化物Ａは、電解質成分と硫黄成分との化合物の形成や、電解質表面への硫黄成分の沈着・付着などを抑制する効果を有する。希土類酸化物Ａの含有量が０．００３モル％未満の場合、希土類酸化物Ａによる硫黄成分が電解質成分に及ぼす悪影響を抑制する効果が十分に発揮されず、電解質シートが硫黄成分を含む雰囲気に曝された場合に、酸素イオン導電率の経時変化を小さく抑えることが困難となる。また、希土類酸化物Ａの含有量が０．５モル％以上である場合、硫黄成分が電解質の表面に沈着・付着しやすくなったり、電解質成分と反応し易くなったりすることが予想される。その結果、燃料の流入が進むにつれて、電解質シートの導電率が次第に劣化する。したがって、電解質成分を構成するジルコニア系酸化物が希土類酸化物Ａを過剰に含んでいると、電解質シートの導電率の経時変化が大きくなる。 It is considered that the decrease in the electrical conductivity of the electrolyte sheet that occurs in an atmosphere containing a sulfur component occurs due to the electrolyte component forming a compound with the sulfur component, or the sulfur component being deposited on or attached to the electrolyte surface. Rare earth oxide A contained in a trace amount in the range of 0.003 mol% or more and less than 0.5 mol% in a zirconia-based oxide stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ) Has the effect of suppressing the formation of a compound of an electrolyte component and a sulfur component, deposition and adhesion of the sulfur component to the electrolyte surface, and the like. When the content of the rare earth oxide A is less than 0.003 mol%, the effect of suppressing the adverse effect of the sulfur component due to the rare earth oxide A on the electrolyte component is not sufficiently exhibited, and the electrolyte sheet is in an atmosphere containing the sulfur component. When exposed, it is difficult to keep the oxygen ion conductivity change with time small. Moreover, when the content of the rare earth oxide A is 0.5 mol% or more, it is expected that the sulfur component is likely to be deposited and adhered to the surface of the electrolyte, or to react easily with the electrolyte component. As a result, the conductivity of the electrolyte sheet gradually deteriorates as the inflow of fuel proceeds. Therefore, if the zirconia-based oxide constituting the electrolyte component contains the rare earth oxide A excessively, the change with time of the conductivity of the electrolyte sheet becomes large.
　硫黄成分に起因する酸素イオン導電率の経時変化をより確実に小さく抑えるために、微量成分として含まれる希土類酸化物Ａは、Ｙ、Ｌａ、Ｐｒ、Ｎｄ、Ｓｍ、Ｇｄ及びＹｂからなる群から選択される少なくとも何れか１種の元素の酸化物であることが好ましく、Ｙ、Ｓｍ、Ｇｄ及びＹｂからなる群から選択される少なくとも何れか１種の元素の酸化物であることがより好ましい。 The rare earth oxide A contained as a trace component is selected from the group consisting of Y, La, Pr, Nd, Sm, Gd and Yb in order to more reliably suppress the temporal change in oxygen ion conductivity caused by the sulfur component. It is preferably an oxide of at least one element selected from the group consisting of Y, Sm, Gd, and Yb, and more preferably an oxide of at least one element selected from the group consisting of Y, Sm, Gd, and Yb.
　形態１－Ａにおけるジルコニア系酸化物では、より一層好ましくは、希土類酸化物Ａが酸化ガドリニウム（Ｇｄ２Ｏ３）であることである。酸化ガドリニウム（Ｇｄ２Ｏ３）は、形態１－Ａにおけるジルコニア系酸化物に希土類酸化物Ａとして含まれる場合、他の希土類酸化物の中でも特に、電解質成分と硫黄成分との化合物の形成や、電解質表面への硫黄成分の沈着・付着などを抑制する効果が高い。したがって、形態１－Ａにおけるジルコニア系酸化物が希土類酸化物Ａとして酸化ガドリニウム（Ｇｄ２Ｏ３）を含むことにより、硫黄成分に起因する酸素イオン導電率の経時変化をより一層確実に小さく抑えることができる。また、形態１－Ａにおけるジルコニア系酸化物が酸化ガドリニウム（Ｇｄ２Ｏ３）を含む場合、酸化ガドリニウム（Ｇｄ２Ｏ３）の含有量は０．００３モル％以上０．２モル％以下であることが好ましい。酸化ガドリニウム（Ｇｄ２Ｏ３）の含有量が０．２モル％を超える場合、酸化ガドリニウムの含有量に見合う程度に効果を高めることができないためである。 In the zirconia-based oxide in Form 1-A, it is more preferable that the rare earth oxide A is gadolinium oxide (Gd 2 O 3 ). When gadolinium oxide (Gd 2 O 3 ) is contained as the rare earth oxide A in the zirconia-based oxide in Form 1-A, among other rare earth oxides, formation of a compound of an electrolyte component and a sulfur component, Highly effective in suppressing the deposition and adhesion of sulfur components to the electrolyte surface. Therefore, when the zirconia-based oxide in Form 1-A contains gadolinium oxide (Gd 2 O 3 ) as the rare earth oxide A, the change over time in the oxygen ion conductivity caused by the sulfur component can be further suppressed to be small. Can do. Further, when zirconia oxide in Embodiment 1-A contains gadolinium oxide (Gd 2 O 3), content is 0.2 mol% or less than 0.003 mole percent gadolinium oxide (Gd 2 O 3) It is preferable. This is because when the content of gadolinium oxide (Gd 2 O 3 ) exceeds 0.2 mol%, the effect cannot be enhanced to the extent that it matches the content of gadolinium oxide.
　形態１－Ａにおけるジルコニア系酸化物が酸化ガドリニウム（Ｇｄ２Ｏ３）を含む場合、酸化イットリウム（Ｙ２Ｏ３）も希土類酸化物Ａとしてさらに添加されることが好ましい。形態１－Ａの電解質シートの電解質成分が、酸化ガドリニウム（Ｇｄ２Ｏ３）と酸化イットリウム（Ｙ２Ｏ３）との両方を希土類酸化物Ａとして含むジルコニア系酸化物で構成されることにより、硫黄成分が電解質成分に及ぼす悪影響を抑制する効果をさらに向上させることができる。酸化ガドリニウム（Ｇｄ２Ｏ３）と酸化イットリウム（Ｙ２Ｏ３）との両方が含まれることによる相乗効果の理由は明らかではないが、酸化イットリウム（Ｙ２Ｏ３）の含有量が０．００３モル％以上０．２モル％以下の範囲の場合に、特に優れた効果を得ることができる。 When the zirconia-based oxide in Form 1-A contains gadolinium oxide (Gd 2 O 3 ), it is preferable that yttrium oxide (Y 2 O 3 ) is further added as the rare earth oxide A. When the electrolyte component of the electrolyte sheet of Form 1-A is composed of a zirconia-based oxide containing both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) as the rare earth oxide A, The effect of suppressing the adverse effect of the sulfur component on the electrolyte component can be further improved. Although the reason for the synergistic effect due to the inclusion of both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) is not clear, the content of yttrium oxide (Y 2 O 3 ) is 0.003. A particularly excellent effect can be obtained when the content is in the range of from mol% to 0.2 mol%.
　形態１－Ａにおけるジルコニア系酸化物は、酸化スカンジウム（Ｓｃ２Ｏ３）を、８モル％以上１５モル％以下で含んでいることが好ましく、８．５モル％以上１２モル％以下で含んでいることがより好ましく、９モル％以上１１モル％以下で含んでいることがより一層好ましい。形態１－Ａにおけるジルコニア系酸化物は、その結晶構造が立方晶を含んでいることが好ましい。結晶構造が立方晶を含んでいる場合は、形態１－Ａにおけるジルコニア系酸化物は、酸化スカンジウム（Ｓｃ２Ｏ３）を９．５モル％以上１２モル％以下で含んでいることが好ましく、１０モル％以上１１．５モル％以下で含んでいることがより好ましい。 The zirconia-based oxide in Form 1-A preferably contains scandium oxide (Sc 2 O 3 ) in an amount of 8 mol% to 15 mol%, and contains 8.5 mol% to 12 mol%. It is more preferable that it is contained in an amount of 9 mol% or more and 11 mol% or less. The zirconia-based oxide in Form 1-A preferably has a cubic crystal structure. When the crystal structure includes cubic crystals, the zirconia-based oxide in Form 1-A preferably contains scandium oxide (Sc 2 O 3 ) in an amount of 9.5 mol% to 12 mol%. More preferably, it is contained in an amount of 10 mol% to 11.5 mol%.
　形態１－Ａにおけるジルコニア系酸化物は、酸化セリウム（ＣｅＯ２）を０．５モル％以上２．５モル％以下で含んでいることが好ましく、０．６モル％以上２モル％以下で含んでいることがより好ましく、０．７モル％以上１．５モル％以下で含んでいることがより一層好ましい。 The zirconia-based oxide in Form 1-A preferably contains cerium oxide (CeO 2 ) in an amount of 0.5 mol% or more and 2.5 mol% or less, and contains 0.6 mol% or more and 2 mol% or less. It is more preferable that it is contained in an amount of 0.7 mol% or more and 1.5 mol% or less.
　（形態１－Ｂ（スカンジア安定化ジルコニア系酸化物））
　形態１－Ｂに係る電解質シートの主成分として含まれる電解質成分は、酸化スカンジウム（Ｓｃ２Ｏ３）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物Ｂを含むジルコニア系酸化物で構成されている。当該希土類酸化物Ｂは、Ｓｃを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である。すなわち、希土類酸化物Ｂは、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ及びＬｕからなる群から選択される少なくとも何れか１種の元素の酸化物である。例えば、形態１－Ｂに係る電解質シートは、安定化剤として酸化スカンジウムが固溶されたジルコニアに、０．００３モル％以上０．５モル％未満の希土類酸化物Ｂがさらに固溶されているジルコニア系酸化物の焼結体によって形成されている。前記ジルコニア系酸化物における希土類酸化物Ｂの合計量は、０．００５モル％以上０．４モル％以下が好ましく、０．０１モル％以上０．３モル％以下がより好ましい。 (Form 1-B (scandia-stabilized zirconia oxide))
The electrolyte component contained as a main component of the electrolyte sheet according to Form 1-B is stabilized with scandium oxide (Sc 2 O 3 ), and is rare earth oxide B having a content of 0.003 mol% or more and less than 0.5 mol%. It is comprised with the zirconia-type oxide containing. The rare earth oxide B is an oxide of at least one element selected from rare earth elements excluding Sc. That is, the rare earth oxide B is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. It is an oxide of a seed element. For example, in the electrolyte sheet according to Form 1-B, 0.003 mol% or more and less than 0.5 mol% of rare earth oxide B is further dissolved in zirconia in which scandium oxide is dissolved as a stabilizer. It is formed of a sintered body of zirconia oxide. The total amount of rare earth oxide B in the zirconia-based oxide is preferably 0.005 mol% to 0.4 mol%, and more preferably 0.01 mol% to 0.3 mol%.
　硫黄成分を含む雰囲気下で生じる電解質シートの導電率の低下は、電解質成分が硫黄成分と化合物を形成したり、硫黄成分が電解質表面へ沈着・付着したりすることなどによって起こると考えられる。酸化スカンジウム（Ｓｃ２Ｏ３）で安定化されたジルコニア系酸化物において、０．００３モル％以上０．５モル％未満の範囲内で微量に含まれる希土類酸化物Ｂは、電解質成分と硫黄成分との化合物の形成や、電解質表面への硫黄成分の沈着・付着などを抑制する効果を有する。希土類酸化物Ｂの含有量が０．００３モル％未満の場合、希土類酸化物Ｂによる硫黄成分が電解質成分に及ぼす悪影響を抑制する効果が十分に発揮されず、電解質シートが硫黄成分を含む雰囲気に曝された場合に、酸素イオン導電率の経時変化を小さく抑えることが困難となる。また、希土類酸化物Ｂの含有量が０．５モル％以上である場合、硫黄成分が電解質の表面に沈着・付着しやすくなったり、電解質成分と反応し易くなったりすることが予想される。その結果、燃料の流入が進むにつれて、電解質シートの導電率が次第に劣化する。したがって、電解質成分を構成するジルコニア系酸化物が希土類酸化物Ｂを過剰に含んでいると、電解質シートの導電率の経時変化が大きくなる。 It is considered that the decrease in the electrical conductivity of the electrolyte sheet that occurs in an atmosphere containing a sulfur component occurs due to the electrolyte component forming a compound with the sulfur component, or the sulfur component being deposited on or attached to the electrolyte surface. In the zirconia-based oxide stabilized with scandium oxide (Sc 2 O 3 ), the rare earth oxide B contained in a trace amount within the range of 0.003 mol% to less than 0.5 mol% is composed of an electrolyte component and a sulfur component. It has the effect of suppressing the formation of the compound and the deposition and adhesion of sulfur components to the electrolyte surface. When the content of the rare earth oxide B is less than 0.003 mol%, the effect of suppressing the adverse effect of the sulfur component due to the rare earth oxide B on the electrolyte component is not sufficiently exhibited, and the electrolyte sheet is in an atmosphere containing the sulfur component. When exposed, it is difficult to keep the oxygen ion conductivity change with time small. Further, when the content of the rare earth oxide B is 0.5 mol% or more, it is expected that the sulfur component easily deposits and adheres to the surface of the electrolyte or reacts easily with the electrolyte component. As a result, the conductivity of the electrolyte sheet gradually deteriorates as the inflow of fuel proceeds. Accordingly, when the zirconia-based oxide constituting the electrolyte component contains the rare earth oxide B excessively, the change with time of the conductivity of the electrolyte sheet becomes large.
　硫黄成分に起因する酸素イオン導電率の経時変化をより確実に小さく抑えるために、微量成分として含まれる希土類酸化物Ｂは、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｇｄ及びＹｂからなる群から選択される少なくとも何れか１種の元素の酸化物であることが好ましく、Ｙ、Ｃｅ、Ｓｍ、Ｇｄ及びＹｂからなる群から選択される少なくとも何れか１種の元素の酸化物であることがより好ましい。 The rare earth oxide B contained as a trace component is a group consisting of Y, La, Ce, Pr, Nd, Sm, Gd, and Yb in order to more reliably suppress the temporal change in oxygen ion conductivity caused by the sulfur component. Preferably, the oxide is an oxide of at least one element selected from the group consisting of Y, Ce, Sm, Gd, and Yb. More preferred.
　形態１－Ｂにおけるジルコニア系酸化物では、より一層好ましくは、希土類酸化物Ｂが酸化セリウム（ＣｅＯ２）であることである。酸化セリウム（ＣｅＯ２）は、形態１－Ｂにおけるジルコニア系酸化物に希土類酸化物Ｂとして含まれる場合、希土類酸化物の中でも特に、電解質成分と硫黄成分との化合物の形成や、電解質表面への硫黄成分の沈着・付着などを抑制する効果が高い。したがって、形態１－Ｂにおけるジルコニア系酸化物が希土類酸化物Ｂとして酸化セリウム（ＣｅＯ２）を含むことにより、硫黄成分に起因する酸素イオン導電率の経時変化をより一層確実に小さく抑えることができる。また、形態１－Ｂにおけるジルコニア系酸化物が酸化セリウム（ＣｅＯ２）を含む場合、その含有量は０．１モル％以上が好ましく、０．２モル％以上がより好ましい。また、形態１－Ｂにおけるジルコニア系酸化物が酸化セリウム（ＣｅＯ２）を含む場合、その含有量は０．４８モル％以下が好ましく、０．４５モル％以下がより好ましい。 In the zirconia-based oxide in Form 1-B, it is more preferable that the rare earth oxide B is cerium oxide (CeO 2 ). When cerium oxide (CeO 2 ) is contained as rare earth oxide B in the zirconia-based oxide in Form 1-B, among other rare earth oxides, formation of a compound of an electrolyte component and a sulfur component, Highly effective in suppressing deposition and adhesion of sulfur components. Therefore, when the zirconia-based oxide in Form 1-B contains cerium oxide (CeO 2 ) as the rare earth oxide B, the change over time in the oxygen ion conductivity caused by the sulfur component can be more reliably suppressed. . Further, when the zirconia-based oxide in Form 1-B contains cerium oxide (CeO 2 ), its content is preferably 0.1 mol% or more, more preferably 0.2 mol% or more. Further, when the zirconia-based oxide in Form 1-B contains cerium oxide (CeO 2 ), its content is preferably 0.48 mol% or less, and more preferably 0.45 mol% or less.
　また、形態１－Ｂにおけるジルコニア系酸化物において、希土類酸化物Ｂが酸化ガドリニウム（Ｇｄ２Ｏ３）である場合も、酸素イオン導電率の経時変化を抑制する高い効果が得られる。形態１－Ｂにおけるジルコニア系酸化物が酸化ガドリニウム（Ｇｄ２Ｏ３）を含む場合、その含有量は０．００３モル％以上０．２モル％以下であることが好ましく、０．００５モル％以上０．１モル％以下がより好ましい。 In addition, in the zirconia-based oxide in Form 1-B, when the rare earth oxide B is gadolinium oxide (Gd 2 O 3 ), a high effect of suppressing change with time in oxygen ion conductivity can be obtained. When the zirconia-based oxide in Form 1-B contains gadolinium oxide (Gd 2 O 3 ), its content is preferably 0.003 mol% or more and 0.2 mol% or less, and 0.005 mol% or more 0.1 mol% or less is more preferable.
　また、形態１－Ｂにおけるジルコニア系酸化物において、希土類酸化物Ｂが酸化イットリウム（Ｙ２Ｏ３）である場合も、酸素イオン導電率の経時変化を抑制する高い効果が得られる。形態１－Ｂにおけるジルコニア系酸化物が酸化イットリウム（Ｙ２Ｏ３）を含む場合、その含有量は０．００３モル％以上０．２モル％以下であることが好ましく、０．００５モル％以上０．１モル％以下がより好ましい。 Further, in the zirconia-based oxide in Form 1-B, when the rare earth oxide B is yttrium oxide (Y 2 O 3 ), a high effect of suppressing the change in oxygen ion conductivity with time can be obtained. When the zirconia-based oxide in Form 1-B contains yttrium oxide (Y 2 O 3 ), its content is preferably 0.003 mol% or more and 0.2 mol% or less, and 0.005 mol% or more 0.1 mol% or less is more preferable.
　形態１－Ｂにおけるジルコニア系酸化物が、酸化ガドリニウム（Ｇｄ２Ｏ３）と酸化イットリウム（Ｙ２Ｏ３）との両方を希土類酸化物Ｂとして含んでいてもよい。形態１－Ｂの電解質シートの電解質成分が、酸化ガドリニウム（Ｇｄ２Ｏ３）と酸化イットリウム（Ｙ２Ｏ３）との両方を希土類酸化物Ｂとして含むジルコニア系酸化物で構成されることにより、硫黄成分が電解質成分に及ぼす悪影響を抑制する効果をさらに向上させることができる。酸化ガドリニウム（Ｇｄ２Ｏ３）と酸化イットリウム（Ｙ２Ｏ３）との両方が含まれることによる相乗効果の理由は明らかではないが、酸化ガドリニウム（Ｇｄ２Ｏ３）と酸化イットリウム（Ｙ２Ｏ３）との合計量が０．００３モル％以上０．２モル％以下であることが好ましく、０．００５モル％以上０．１モル％以下がより好ましい。 The zirconia-based oxide in Form 1-B may contain both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) as rare earth oxide B. The electrolyte component of the electrolyte sheet of Form 1-B is composed of a zirconia-based oxide containing both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) as rare earth oxide B. The effect of suppressing the adverse effect of the sulfur component on the electrolyte component can be further improved. The reason for the synergistic effect due to the inclusion of both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) is not clear, but gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O). 3 ) is preferably from 0.003 mol% to 0.2 mol%, more preferably from 0.005 mol% to 0.1 mol%.
　形態１－Ｂにおけるジルコニア系酸化物は、酸化スカンジウム（Ｓｃ２Ｏ３）を、４モル％以上１５モル％以下で含んでいることが好ましい。形態１－Ｂにおけるジルコニア系酸化物の結晶系が正方晶系である場合、当該ジルコニア系酸化物は酸化スカンジウム（Ｓｃ２Ｏ３）を４モル％以上６．５モル％以下で含んでいることが好ましい。形態１－Ｂにおけるジルコニア系酸化物の結晶系が立方晶系である場合、当該ジルコニア系酸化物は酸化スカンジウム（Ｓｃ２Ｏ３）を９モル％以上１３モル％以下で含んでいることが好ましく、９．５モル％以上１２モル％以下で含んでいることがより好ましく、１０モル％以上１１．５モル％以下で含んでいることがより一層好ましい。 The zirconia-based oxide in Form 1-B preferably contains scandium oxide (Sc 2 O 3 ) in an amount of 4 mol% to 15 mol%. When the crystal system of the zirconia-based oxide in Form 1-B is a tetragonal system, the zirconia-based oxide contains scandium oxide (Sc 2 O 3 ) in an amount of 4 mol% to 6.5 mol%. Is preferred. When the crystal system of the zirconia-based oxide in Form 1-B is a cubic system, the zirconia-based oxide preferably contains scandium oxide (Sc 2 O 3 ) in an amount of 9 mol% to 13 mol%. 9.5 mol% or more and 12 mol% or less, more preferably 10 mol% or more and 11.5 mol% or less.
　立方晶系とは、結晶構造が立方晶を主体とする安定化ジルコニアを示す。具体的には、固体電解質シートにおけるジルコニア結晶のＸ線回折パターンから各ピーク強度を求め、各強度値と下記式から求められた立方晶比率（％）が、５０％以上であることである。立方晶系の安定化ジルコニアは、立方晶比率が９０％以上であることが好ましく、９５％以上であることがより好ましく、９７％以上がさらに好ましい。
立方晶比率（％）＝（１００－単斜晶比率）×［ｃ（４００）］÷［ｔ（４００）＋ｔ（００４）＋ｃ（４００）］
［式中、ｃ（４００）は立方晶（４００）面のピーク強度を示し、ｔ（４００）は正方晶（４００）面のピーク強度を示し、ｔ（００４）は正方晶（００４）面のピーク強度を示す］ The cubic system means stabilized zirconia whose crystal structure is mainly composed of cubic crystals. Specifically, each peak intensity is obtained from the X-ray diffraction pattern of the zirconia crystal in the solid electrolyte sheet, and the cubic ratio (%) obtained from each intensity value and the following formula is 50% or more. The cubic stabilized zirconia preferably has a cubic ratio of 90% or more, more preferably 95% or more, and still more preferably 97% or more.
Cubic crystal ratio (%) = (100−monoclinic crystal ratio) × [c (400)] ÷ [t (400) + t (004) + c (400)]
[Wherein c (400) represents the peak intensity of the cubic (400) plane, t (400) represents the peak intensity of the tetragonal (400) plane, and t (004) represents the tetragonal (004) plane. Shows peak intensity]
　正方晶系とは、結晶構造が正方晶を主体とする安定化ジルコニアを示す。具体的には、固体電解質シートにおけるジルコニア結晶のＸ線回折パターンから各ピーク強度を求め、各強度値と下記式から求められた正方晶比率（％）が、５０％以上であることである。正方晶系の安定化ジルコニアは、
正方晶比率（％）＝（１００－単斜晶比率）×［ｔ（４００）＋ｔ（００４）］÷［ｔ（４００）＋ｔ（００４）＋ｃ（４００）］
［式中、ｔ（４００）は正方晶（４００）面のピーク強度を示し、ｔ（００４）は正方晶（００４）面のピーク強度を示し、ｃ（４００）は立方晶（４００）面のピーク強度を示す］ The tetragonal system means stabilized zirconia whose crystal structure is mainly tetragonal. Specifically, each peak intensity is obtained from the X-ray diffraction pattern of the zirconia crystal in the solid electrolyte sheet, and the tetragonal crystal ratio (%) obtained from each intensity value and the following formula is 50% or more. Tetragonal stabilized zirconia
Tetragonal crystal ratio (%) = (100−monoclinic crystal ratio) × [t (400) + t (004)] ÷ [t (400) + t (004) + c (400)]
[Where t (400) represents the peak intensity of the tetragonal (400) plane, t (004) represents the peak intensity of the tetragonal (004) plane, and c (400) represents the cubic (400) plane. Shows peak intensity]
　本実施形態の電解質シート（以下、本実施形態の電解質シートとは、形態１－Ａの電解質シート及び形態１－Ｂの電解質シートの両方を指す。）は、上記成分以外に、例えば、酸化ハフニウム、酸化アルミニウム、酸化チタン、酸化ニオブ、酸化タンタル、酸化マンガン等の酸化物や、ＬａＡｌＯ３、ＭｇＡｌ２Ｏ４、Ａｌ２ＴｉＯ５及びＬａＧａＯ３などの複合酸化物を、合計で５質量％以下の範囲でさらに含んでいてもよい。その他、Ｌｉ、Ｎａ、Ｋ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ，Ｌａ，Ｐｒ，Ｎｄ，Ｙｂ，Ｃｒ，Ｗ，Ｆｅ，Ｃｏ，Ｎｉ，Ｃｕ，Ｚｎ，Ｂ，Ｇａ，Ｓｉ，Ｇｅ、Ｐ等が含まれていてもよい。その場合、これら成分の含有量は、酸化物換算で合計１．０質量％以下が望ましい。 The electrolyte sheet of the present embodiment (hereinafter, the electrolyte sheet of the present embodiment refers to both the electrolyte sheet of Form 1-A and the electrolyte sheet of Form 1-B), for example, hafnium oxide other than the above components And oxides such as aluminum oxide, titanium oxide, niobium oxide, tantalum oxide, and manganese oxide, and composite oxides such as LaAlO 3 , MgAl 2 O 4 , Al 2 TiO 5, and LaGaO 3 in a total amount of 5% by mass or less. It may be further included in the range. In addition, Li, Na, K, Mg, Ca, Sr, Ba, La, Pr, Nd, Yb, Cr, W, Fe, Co, Ni, Cu, Zn, B, Ga, Si, Ge, P, etc. are included. It may be. In that case, the total content of these components is preferably 1.0% by mass or less in terms of oxide.
　本実施形態の電解質シートの形態は、特に制限されず、平板状、湾曲状、膜状、円筒状、円筒平板状およびハニカム状が例示される。本実施形態の電解質シートの厚さは、例えば、１０μｍ以上４００μｍ以下とできる。本実施形態の電解質シートが電解質支持型セル（ＥＳＣ）に適用される場合、電解質シートの厚さは、例えば８０μｍ以上４００μｍ以下が好ましく、９０μｍ以上３００μｍ以下がより好ましい。 The form of the electrolyte sheet of the present embodiment is not particularly limited, and examples thereof include a flat plate shape, a curved shape, a film shape, a cylindrical shape, a cylindrical flat plate shape, and a honeycomb shape. The thickness of the electrolyte sheet of the present embodiment can be, for example, 10 μm or more and 400 μm or less. When the electrolyte sheet of this embodiment is applied to an electrolyte support cell (ESC), the thickness of the electrolyte sheet is preferably, for example, 80 μm or more and 400 μm or less, and more preferably 90 μm or more and 300 μm or less.
　本実施形態の電解質シートの大きさは、特に制限されないが、例えば５０ｃｍ２以上９００ｃｍ２以下、好ましくは７０ｃｍ２以上５００ｃｍ２以下の平面面積を有する電解質シートが、好適に用いられる。 Electrolytes size of the sheet of the present embodiment is not particularly limited, for example, 50 cm 2 or more 900 cm 2 or less, preferably electrolyte sheet having a planar area of 70cm 2 or more 500 cm 2 or less are preferably used.
　上記電解質シートの場合、シートの形状としては、円形、楕円形およびＲ（アール）を持った角形など何れでもよい。これらのシート内に、同様の円形、楕円形、Ｒ（アール）を持った角形などの穴を１つもしくは２つ以上有するものであってもよい。なお、上記平面面積とは、シートが穴を有する場合は、当該穴の面積を含んだシート表面の面積（シート外形によって決定される面積）を意味する。 In the case of the above electrolyte sheet, the shape of the sheet may be any of a circle, an ellipse, and a square with R (R). These sheets may have one or two or more holes such as a similar circular shape, an elliptical shape, and a rectangular shape having R (R). In addition, the said plane area means the area (area determined by sheet | seat external shape) including the area of the said hole, when a sheet | seat has a hole.
　次に、本実施形態の電解質シートの製造方法について説明する。本実施形態の電解質シートの製造には、一般的なＳＯＦＣ用電解質シートの製造方法を利用できる。すなわち、電解質シート用のグリーンシートを準備し、このグリーンシートを焼成することによって、本実施形態の電解質シートを得ることができる。 Next, a method for manufacturing the electrolyte sheet of this embodiment will be described. For manufacturing the electrolyte sheet of the present embodiment, a general method for manufacturing an electrolyte sheet for SOFC can be used. That is, the electrolyte sheet of this embodiment can be obtained by preparing a green sheet for an electrolyte sheet and firing the green sheet.
　まず、本実施形態の電解質シートの電解質成分の原料として用いられる、ジルコニア系酸化物の原料粉末が準備される。原料粉末を製造する方法には、粉体を製造できる方法であれば何れの方法でも用いることができるが、本実施形態では液相プロセスである共沈法が好適に用いられる。本実施形態の電解質シートの原料粉末は、ジルコニウム化合物及びスカンジウム化合物と、必要に応じて適宜選択されるセリウム化合物、ガドリニウム化合物及びイットリウム化合物等の希土類元素の化合物とを含む溶液と、沈殿剤とを混合して共沈させ、得られた沈殿物を酸化性雰囲気下で焼成することにより、得ることができる。 First, a zirconia-based oxide raw material powder used as a raw material for the electrolyte component of the electrolyte sheet of the present embodiment is prepared. As a method for producing the raw material powder, any method can be used as long as it is a method capable of producing a powder, but in this embodiment, a coprecipitation method which is a liquid phase process is preferably used. The raw material powder of the electrolyte sheet of the present embodiment includes a solution containing a zirconium compound and a scandium compound, and a rare earth element compound such as a cerium compound, a gadolinium compound, and an yttrium compound, which are appropriately selected as necessary, and a precipitant. It can be obtained by mixing and coprecipitating, and baking the obtained precipitate in an oxidizing atmosphere.
　本実施形態において用いられる各成分の原料は特に限定されず、硝酸塩、炭酸塩、硫酸塩、塩化物及びオキシ塩化物等の無機酸塩、酢酸塩及びシュウ酸塩等の有機酸塩が例示される。特に、硝酸塩、塩化物及びオキシ塩化物が好適に用いられる。なお、各原料を溶媒に溶解して溶液を得る方法は、原料を溶解できる方法であればよいため、特には限定されない。溶媒としては、水及びアルコール類等が例示される。 The raw material of each component used in the present embodiment is not particularly limited, and examples thereof include inorganic acid salts such as nitrates, carbonates, sulfates, chlorides and oxychlorides, and organic acid salts such as acetates and oxalates. The In particular, nitrates, chlorides and oxychlorides are preferably used. In addition, since the method of melt | dissolving each raw material in a solvent and obtaining a solution should just be a method which can melt | dissolve a raw material, it is not specifically limited. Examples of the solvent include water and alcohols.
　また、添加する沈殿剤は特に限定されず、水酸化ナトリウム、水酸化カリウム、炭酸ナトリウム、炭酸アンモニウム及びアンモニア等の塩基が例示される。これらの中で、特にアンモニアを用いることが好ましい。これらの沈殿剤は、通常、溶液として添加することが好ましい。 Further, the precipitating agent to be added is not particularly limited, and examples thereof include bases such as sodium hydroxide, potassium hydroxide, sodium carbonate, ammonium carbonate and ammonia. Among these, it is particularly preferable to use ammonia. These precipitating agents are usually preferably added as a solution.
　各成分の原料を含む溶液と沈殿剤との混合方法は特に限定されない。各成分の原料を含む溶液に沈殿剤溶液を滴下する方法、沈殿剤溶液に各成分の原料を含む溶液を滴下する方法等が例示される。 The mixing method of the solution containing the raw materials of each component and the precipitant is not particularly limited. Examples thereof include a method of dropping a precipitant solution into a solution containing the raw materials of each component, a method of dropping a solution containing the raw materials of each component into the precipitant solution, and the like.
　上記方法によって生成した沈殿物は、水洗及びろ過等を行い、固液分離することにより回収することができる。得られた沈殿物は、通常、乾燥後に焼成されて、酸化物となる。この焼成は、酸化性雰囲気下で行えばよく、好ましくは大気中で行われる。焼成温度は特に限定されないが、通常５００～１３００℃程度、好ましくは６００～１２００℃程度とすればよい。焼成温度が５００℃未満の場合には、沈殿物が充分に酸化されない場合がある。焼成温度が１３００℃を超えると、粒成長により強い凝集が起こる場合がある。得られた酸化物は、必要に応じて粉砕されてもよい。粉砕の方法は特には限定されず、湿式粉砕及び乾式粉砕が例示される。 The precipitate produced by the above method can be recovered by solid-liquid separation by washing with water and filtering. The obtained precipitate is usually baked after drying to become an oxide. This firing may be performed in an oxidizing atmosphere, and is preferably performed in the air. The firing temperature is not particularly limited, but is usually about 500 to 1300 ° C., preferably about 600 to 1200 ° C. When the firing temperature is less than 500 ° C., the precipitate may not be sufficiently oxidized. When the firing temperature exceeds 1300 ° C., strong aggregation may occur due to grain growth. The obtained oxide may be pulverized as necessary. The method of pulverization is not particularly limited, and examples thereof include wet pulverization and dry pulverization.
　本実施形態のジルコニア系酸化物の結晶構造は、好ましくは立方晶相単相もしくは正方晶単相である。
　電解質材料の結晶構造は、強度的および酸素イオン伝導性に問題がない範囲で菱面体晶相を僅かに含んだ、立方晶相と菱面体晶相（Ｒ相）との混相であってもよい。本実施形態のジルコニア系酸化物は、典型的には、Ｘ線結晶構造解析における２θ＝５１．３°（菱面体晶相に対応）での回折強度がバックグランドレベルとほぼ同じである。Ｘ線結晶構造解析における２θ＝５１．３°での回折強度は、例えばバックグランドレベルの１．２倍以下であり、好ましくは１．１倍以下であり、より好ましくは１．０５倍以下である。さらに、正方晶相や単斜晶相を僅かに含んだ、正方晶相や単斜晶相と立方晶相との混相であってもよい。 The crystal structure of the zirconia-based oxide of the present embodiment is preferably a cubic phase single phase or a tetragonal single phase.
The crystal structure of the electrolyte material may be a mixed phase of a cubic phase and a rhombohedral phase (R phase) that includes a slight amount of rhombohedral phase as long as there is no problem in strength and oxygen ion conductivity. . The zirconia-based oxide of this embodiment typically has a diffraction intensity at 2θ = 51.3 ° (corresponding to rhombohedral phase) in the X-ray crystal structure analysis that is substantially the same as the background level. The diffraction intensity at 2θ = 51.3 ° in the X-ray crystal structure analysis is, for example, 1.2 times or less, preferably 1.1 times or less, more preferably 1.05 times or less of the background level. is there. Further, it may be a mixed phase of a tetragonal phase, a monoclinic phase and a cubic phase, which slightly contains a tetragonal phase or a monoclinic phase.
　また、電解質材料の結晶構造は、強度的および酸素イオン伝導性に問題がない範囲で、単斜晶相や立方晶相を僅かに含んだ、単斜晶相や立方晶相と正方晶相との混相であってもよい。 In addition, the crystal structure of the electrolyte material has a monoclinic phase, a cubic phase, and a tetragonal phase, with a slight monoclinic phase and cubic phase, as long as there is no problem in strength and oxygen ion conductivity. It may be a mixed phase.
　次に、得られた原料粉末を用いて、電解質シート用のグリーンシートを作製する。電解質シート用のグリーンシートの作製には、テープ成形法が好適に用いられ、特にドクターブレード法及びカレンダー法が好適に用いられる。具体的には、まず、上記方法で得られたジルコニア系酸化物の原料粉末に、バインダー及び添加剤を添加し、さらに必要に応じて分散媒等を添加して、スラリーを調製する。このスラリーを、支持板又はキャリヤフィルム上に敷き延べてシート状に成形し、これを乾燥させて分散媒を揮発させて、グリーンシートを得る。このグリーンシートを切断及び／又はパンチング等により適切なサイズに揃えて、電解質シート用のグリーンシートを作製する。なお、スラリーの作製に用いられるバインダー、溶剤及び分散剤等には、ＳＯＦＣ用電解質シートの製造に用いられる公知のバインダー、溶剤及び分散剤等が使用できる。 Next, a green sheet for an electrolyte sheet is produced using the obtained raw material powder. For producing a green sheet for an electrolyte sheet, a tape forming method is preferably used, and in particular, a doctor blade method and a calendar method are preferably used. Specifically, first, a binder and an additive are added to the zirconia-based oxide raw material powder obtained by the above method, and a dispersion medium or the like is further added as necessary to prepare a slurry. This slurry is spread on a support plate or a carrier film and formed into a sheet shape, which is dried to volatilize the dispersion medium to obtain a green sheet. The green sheet is made into an appropriate size by cutting and / or punching or the like to produce a green sheet for an electrolyte sheet. In addition, as the binder, the solvent, the dispersant, and the like used for the preparation of the slurry, a known binder, a solvent, a dispersant, and the like that are used for manufacturing the SOFC electrolyte sheet can be used.
　次に、電解質シート用のグリーンシートを焼成する。上記のとおり得られた電解質シート用のグリーンシートを、棚板上の多孔質セッター上に載置する。例えば、棚板上に、多孔質セッターと、上記のように作製された電解質シート用のグリーンシートとを、最下層及び最上層に多孔質セッターが配置されるように交互に積み重ねて、多孔質セッターとグリーンシートとからなる積層体を配置してもよい。このように配置されたグリーンシートを、例えば１２００～１５００℃、好ましくは１２５０～１４２５℃程度の温度で、１～５時間程度加熱焼成する。焼成時の温度が１５００℃を超えると、焼結体中に菱面体晶や単斜晶が生成し、電解質シートの常温での強度（常温強度）と高温耐久性とが共に悪くなる場合がある。一方、焼成温度が１２００℃未満では、焼結不足となって緻密質のシートが得られ難くなり、電解質シートが強度不足になるだけでなく、ガスを透過してしまう場合もある。しかし、上記温度範囲で焼成を行うと、単斜晶や菱面体の生成が抑制されると共に、得られるシートの相対密度を９７％以上、好ましくは９９％以上とすることができるので、常温強度と高温耐久性とに優れた焼結体シートが得られる。なお、相対密度とは、理論密度に対するアルキメデス法で測定した密度の相対値（アルキメデス法で測定した密度／理論密度）である。なお、グリーンシートの焼成に用いられる多孔質セッターには、ＳＯＦＣ用電解質シートの製造に用いられる公知の多孔質セッターが使用できる。 Next, the green sheet for the electrolyte sheet is fired. The green sheet for an electrolyte sheet obtained as described above is placed on a porous setter on a shelf board. For example, the porous setter and the green sheet for the electrolyte sheet produced as described above are alternately stacked on the shelf so that the porous setter is disposed in the lowermost layer and the uppermost layer, You may arrange | position the laminated body which consists of a setter and a green sheet. The green sheet thus arranged is heated and fired at a temperature of about 1200 to 1500 ° C., preferably about 1250 to 1425 ° C. for about 1 to 5 hours. When the firing temperature exceeds 1500 ° C., rhombohedral crystals and monoclinic crystals are formed in the sintered body, and both the strength at normal temperature (room temperature strength) and high-temperature durability of the electrolyte sheet may deteriorate. . On the other hand, if the firing temperature is less than 1200 ° C., it becomes difficult to obtain a dense sheet due to insufficient sintering, and not only the electrolyte sheet becomes insufficient in strength but also gas may pass therethrough. However, firing in the above temperature range suppresses the formation of monoclinic crystals and rhombohedrons, and the relative density of the obtained sheet can be 97% or more, preferably 99% or more. And a sintered body sheet excellent in durability at high temperature. The relative density is a relative value of density measured by Archimedes method with respect to theoretical density (density measured by Archimedes method / theoretical density). In addition, the well-known porous setter used for manufacture of the electrolyte sheet for SOFC can be used for the porous setter used for baking of a green sheet.
　なお、上記の電解質シートの製造方法では、ジルコニア系酸化物の原料粉末を準備する工程を実施する製造方法の例を説明したが、この方法に限定されない。例えば、酸化スカンジウム（Ｓｃ２Ｏ３）及び酸化セリウム（ＣｅＯ２）で安定化されたジルコニア粉末、又は、酸化スカンジウム（Ｓｃ２Ｏ３）で安定化されたジルコニア粉末と、希土類酸化物、希土類元素を含む金属又は希土類元素を含む化合物とを、それぞれ原料粉末として用いて、スラリーの作製、グリーンシートの作製及び電解質シートの作製を順次実施することも可能である。また、原料粉末として、予め希土類元素を含有している酸化スカンジウム（Ｓｃ２Ｏ３）及び酸化セリウム（ＣｅＯ２）で安定化されたジルコニア粉末、又は、酸化スカンジウム（Ｓｃ２Ｏ３）で安定化されたジルコニア粉末を用いることも可能である。 In addition, although the example of the manufacturing method which implements the process of preparing the raw material powder of a zirconia-type oxide was demonstrated in said manufacturing method of an electrolyte sheet, it is not limited to this method. For example, zirconia powder stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ), or zirconia powder stabilized with scandium oxide (Sc 2 O 3 ), a rare earth oxide, and a rare earth element It is also possible to sequentially prepare a slurry, a green sheet, and an electrolyte sheet using a metal-containing metal or a compound containing a rare earth element as a raw material powder. Further, as raw material powder, stabilized with zirconia powder previously stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ) containing rare earth elements, or stabilized with scandium oxide (Sc 2 O 3 ). It is also possible to use a zirconia powder made.
　（実施形態２）
　本発明の電解質支持型セルの実施形態について、具体的に説明する。図１は、本実施形態の電解質支持型セルの構成の一例を示す断面図である。 (Embodiment 2)
The embodiment of the electrolyte-supporting cell of the present invention will be specifically described. FIG. 1 is a cross-sectional view showing an example of the configuration of the electrolyte-supporting cell of the present embodiment.
　本実施形態の電解質支持型セル１は、燃料極１１と、空気極１２と、燃料極１１と空気極１２との間に配置されたＳＯＦＣ用電解質シート１３とを備えている。電解質シート１３には、実施形態１で説明したＳＯＦＣ用電解質シート（形態１－Ａ又は形態１－Ｂの電解質シート）が用いられる。燃料極１１及び空気極１２には、公知のＳＯＦＣに用いられる燃料極及び空気極が、それぞれ適用できる。 The electrolyte support cell 1 of the present embodiment includes a fuel electrode 11, an air electrode 12, and an SOFC electrolyte sheet 13 disposed between the fuel electrode 11 and the air electrode 12. As the electrolyte sheet 13, the SOFC electrolyte sheet described in Embodiment 1 (the electrolyte sheet of Form 1-A or Form 1-B) is used. As the fuel electrode 11 and the air electrode 12, a fuel electrode and an air electrode used in a known SOFC can be applied, respectively.
　本実施形態の電解質支持型セル１は、実施形態１で説明した方法で得られる電解質シートの一方の主面上に燃料極１１を形成し、他方の主面上に空気極１２を形成することによって製造できる。まず、燃料極１１又は空気極１２を構成する材料の粉体に、バインダー及び溶剤を添加し、さらに必要に応じて分散剤等を添加してスラリーを調製する。このスラリーを、電解質シート１３の一方又は他方の主面上に所定の厚さで塗布し、その塗膜を乾燥させることによって、燃料極１１用又は空気極１２用のグリーン層が形成される。そのグリーン層を焼成することによって、燃料極１１又は空気極１２が得られる。焼成温度等の焼成条件は、燃料極１１及び空気極１２に用いられるそれぞれの材料の種類等に応じて、適宜決定すればよい。燃料極１１及び空気極１２を構成する材料には、公知のＳＯＦＣの燃料極及び空気極に用いられる材料を、それぞれ用いることができる。また、燃料極１１及び空気極１２用のスラリーの作製に用いられるバインダー及び溶媒等の種類には特に制限がなく、ＳＯＦＣの燃料極及び空気極の製造方法で公知となっているバインダー及び溶剤等の中から適宜選択できる。 In the electrolyte supporting cell 1 of the present embodiment, the fuel electrode 11 is formed on one main surface of the electrolyte sheet obtained by the method described in the first embodiment, and the air electrode 12 is formed on the other main surface. Can be manufactured. First, a binder and a solvent are added to the powder of the material constituting the fuel electrode 11 or the air electrode 12, and a dispersant is added as necessary to prepare a slurry. This slurry is applied to one or the other main surface of the electrolyte sheet 13 with a predetermined thickness, and the coating layer is dried to form a green layer for the fuel electrode 11 or the air electrode 12. By firing the green layer, the fuel electrode 11 or the air electrode 12 is obtained. The firing conditions such as the firing temperature may be appropriately determined according to the type of each material used for the fuel electrode 11 and the air electrode 12. As materials constituting the fuel electrode 11 and the air electrode 12, materials used for a known SOFC fuel electrode and air electrode can be used, respectively. Also, there are no particular limitations on the types of binders and solvents used in the preparation of the slurry for the fuel electrode 11 and the air electrode 12, and binders and solvents known in the SOFC fuel electrode and air electrode manufacturing methods are known. Can be selected as appropriate.
　本実施形態の電解質支持型セル１は、実施形態１で説明したように、硫黄成分を含む雰囲気に曝された場合であっても酸素イオン導電率の低下を抑制できるＳＯＦＣ用電解質シートを、固体電解質層として備えている。したがって、本実施形態の電解質支持型セル１は、硫黄成分を含む燃料が燃料極に供給される場合であっても、耐久性の低下を小さく抑えることができる。 As described in the first embodiment, the electrolyte-supporting cell 1 of the present embodiment is a solid-state electrolyte sheet for SOFC that can suppress a decrease in oxygen ion conductivity even when exposed to an atmosphere containing a sulfur component. It is provided as an electrolyte layer. Therefore, the electrolyte-supporting cell 1 of the present embodiment can suppress a decrease in durability even when fuel containing a sulfur component is supplied to the fuel electrode.
　（実施形態３）
　本発明のＳＯＦＣ用単セルの実施形態について、具体的に説明する。 (Embodiment 3)
The embodiment of the single cell for SOFC of the present invention will be specifically described.
　本実施形態のＳＯＦＣ用単セルは、燃料極と、空気極と、前記燃料極と前記空気極との間に配置された固体電解質層とを備える。前記燃料極、前記空気極及び前記固体電解質層から選ばれる少なくとも何れか１つが、
　酸化スカンジウム（Ｓｃ２Ｏ３）及び酸化セリウム（ＣｅＯ２）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物（以下、希土類酸化物Ｃということがある。）を含むジルコニア系酸化物（スカンジアセリア安定化ジルコニア系酸化物）を電解質成分として含み、当該希土類酸化物ＣがＳｃ及びＣｅを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である、
又は、
　酸化スカンジウム（Ｓｃ２Ｏ３）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物（以下、希土類酸化物Ｄということがある。）を含むジルコニア系酸化物（スカンジア安定化ジルコニア系酸化物）を電解質成分として含み、当該希土類酸化物ＤがＳｃを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である。 The single cell for SOFC of the present embodiment includes a fuel electrode, an air electrode, and a solid electrolyte layer disposed between the fuel electrode and the air electrode. At least one selected from the fuel electrode, the air electrode, and the solid electrolyte layer,
It is stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ), and is rare earth oxide (hereinafter referred to as rare earth oxide C) of 0.003 mol% or more and less than 0.5 mol%. ) -Containing zirconia-based oxide (scandiaceria-stabilized zirconia-based oxide) as an electrolyte component, and the rare earth oxide C is an oxide of at least one element selected from rare earth elements excluding Sc and Ce Is,
Or
Zirconia-based oxide stabilized with scandium oxide (Sc 2 O 3 ) and containing rare earth oxide (hereinafter sometimes referred to as rare earth oxide D) in an amount of 0.003 mol% to less than 0.5 mol% (Scandia-stabilized zirconia-based oxide) as an electrolyte component, and the rare earth oxide D is an oxide of at least one element selected from rare earth elements excluding Sc.
　ここで、「０．００３モル％以上０．５モル％未満の希土類酸化物Ｃ」とは、希土類酸化物Ｃの合計量が０．００３モル％以上０．５モル％未満であるということを意味する。また、「０．００３モル％以上０．５モル％未満の希土類酸化物Ｄ」とは、希土類酸化物Ｄの合計量が０．００３モル％以上０．５モル％未満であることを意味する。以降についても、同様である。 Here, “0.003 mol% or more and less than 0.5 mol% rare earth oxide C” means that the total amount of rare earth oxide C is 0.003 mol% or more and less than 0.5 mol%. means. In addition, “0.003 mol% or more and less than 0.5 mol% rare earth oxide D” means that the total amount of rare earth oxide D is 0.003 mol% or more and less than 0.5 mol%. . The same applies to the subsequent steps.
　換言すると、本実施形態のＳＯＦＣ用単セルは、燃料極、空気極及び固体電解質層から選ばれる少なくとも何れか１つが、電解質成分として、酸化スカンジウム（Ｓｃ２Ｏ３）で安定化されたジルコニアに０．００３モル％以上０．５モル％未満の微量の希土類酸化物が添加されたジルコニア系酸化物（スカンジア安定化ジルコニア系酸化物）を含むこと、また、スカンジア安定化ジルコニア系酸化物に希土類酸化物として添加される酸化セリウム（ＣｅＯ２）の含有量が０．５モル％以上となる場合は、酸化セリウム（ＣｅＯ２）はジルコニアの安定化剤として機能し、Ｃｅ以外の他の希土類元素の酸化物が０．００３モル％以上０．５モル％未満の範囲で添加されたジルコニア系酸化物（スカンジアセリア安定化ジルコニア系酸化物）を含むこと、を特徴としている。 In other words, the SOFC single cell of this embodiment is made of zirconia in which at least one selected from the fuel electrode, the air electrode, and the solid electrolyte layer is stabilized with scandium oxide (Sc 2 O 3 ) as an electrolyte component. It contains a zirconia-based oxide (scandia-stabilized zirconia-based oxide) to which a trace amount of rare-earth oxide of 0.003 mol% or more and less than 0.5 mol% is added. When the content of cerium oxide (CeO 2 ) added as an oxide is 0.5 mol% or more, cerium oxide (CeO 2 ) functions as a zirconia stabilizer, and other rare earth elements other than Ce Zirconia-based oxides (scandiaceria-stabilized zirconia-based oxides) added in an amount of 0.003 mol% or more and less than 0.5 mol% ) Include, are characterized.
　以下、上記ジルコニア系酸化物（上記スカンジアセリア安定化ジルコニア系酸化物及び上記スカンジア安定化ジルコニア系酸化物）を、「本実施形態のジルコニア系酸化物」と記載することがある。 Hereinafter, the zirconia-based oxide (the scandiaceria-stabilized zirconia-based oxide and the scandia-stabilized zirconia-based oxide) may be referred to as “zirconia-based oxide of this embodiment”.
　固体電解質層が本実施形態のジルコニア系酸化物を含む場合、固体電解質層は、硫黄成分を含む雰囲気に曝された場合であっても、酸素イオン導電率の低下を抑制できる。したがって、このような固体電解質層を備えたＳＯＦＣ用単セルは、都市ガスを改質することで生成した水素が燃料として用いられる場合であって、しかもその燃料に硫黄成分が含まれる可能性がある場合であっても、耐久性の低下を小さく抑えることができる。例えば、都市ガスを燃料に利用するＳＯＦＣシステムにおいて、燃料電池外に改質器を設けて都市ガスを改質するシステムの場合、改質器と共に脱硫装置も設けられる場合が多い。しかし、都市ガスをＳＯＦＣ内で直接改質する内部改質型のＳＯＦＣが用いられるシステムでは、脱硫装置が設けられない場合もある。したがって、本実施形態のＳＯＦＣ用単セルの構成は、特に、内部改質型のＳＯＦＣに適用された場合に、優れた効果を奏する。 When the solid electrolyte layer contains the zirconia-based oxide of the present embodiment, the solid electrolyte layer can suppress a decrease in oxygen ion conductivity even when it is exposed to an atmosphere containing a sulfur component. Therefore, the SOFC single cell provided with such a solid electrolyte layer is a case where hydrogen generated by reforming city gas is used as a fuel, and the fuel may contain a sulfur component. Even in some cases, the decrease in durability can be kept small. For example, in an SOFC system that uses city gas as fuel, in a system that reforms city gas by providing a reformer outside the fuel cell, a desulfurization device is often provided along with the reformer. However, in a system in which an internal reforming SOFC that directly reforms city gas in the SOFC is used, a desulfurization apparatus may not be provided. Therefore, the configuration of the single cell for SOFC of the present embodiment has an excellent effect particularly when applied to an internal reforming SOFC.
　本実施形態のジルコニア系酸化物は、燃料極及び／又は空気極に電極組成物の一部として含まれていてもよい。例えば燃料極は、一般に、導電性を与えるための導電成分と、骨格成分となる電解質成分とを主たる構成材料として含んでいる。そこで、燃料極に電解質成分として本実施形態のジルコニア系酸化物が含まれることにより、硫黄成分を含む燃料が燃料極に供給される場合であっても、燃料極中の電解質成分と硫黄成分との化合物の形成や、電解質表面への硫黄成分の沈着・付着などが抑制される。したがって、電解質成分と硫黄成分との化合物の形成や、電解質表面への硫黄成分の沈着・付着などに起因する燃料極の特性劣化を抑制することができる。なお、本実施形態のジルコニア系酸化物が空気極に含まれる場合も同様の効果が得られる。 The zirconia-based oxide of the present embodiment may be included in the fuel electrode and / or the air electrode as part of the electrode composition. For example, the fuel electrode generally includes a conductive component for imparting conductivity and an electrolyte component as a skeleton component as main constituent materials. Therefore, even when a fuel containing a sulfur component is supplied to the fuel electrode by including the zirconia-based oxide of the present embodiment as an electrolyte component in the fuel electrode, the electrolyte component and the sulfur component in the fuel electrode The formation of this compound and the deposition and adhesion of sulfur components on the electrolyte surface are suppressed. Therefore, it is possible to suppress the deterioration of the characteristics of the fuel electrode due to the formation of a compound of the electrolyte component and the sulfur component and the deposition / attachment of the sulfur component to the electrolyte surface. In addition, the same effect is acquired also when the zirconia-type oxide of this embodiment is contained in an air electrode.
　以下に、本実施形態のＳＯＦＣ用単セルが、燃料極、空気極及び固体電解質層から選ばれる少なくとも何れか１つに上記スカンジアセリア安定化ジルコニア系酸化物を電解質成分として含んでいる形態（形態３－Ａ）と、燃料極、空気極及び固体電解質層から選ばれる少なくとも何れか１つに上記スカンジア安定化ジルコニア系酸化物を電解質成分として含んでいる形態（形態３－Ｂ）とについて、それぞれ説明する。 Hereinafter, the SOFC single cell of the present embodiment includes the scandiaceria-stabilized zirconia-based oxide as an electrolyte component in at least one selected from a fuel electrode, an air electrode, and a solid electrolyte layer (form) 3-A) and a form (form 3-B) in which at least one selected from a fuel electrode, an air electrode, and a solid electrolyte layer contains the scandia-stabilized zirconia-based oxide as an electrolyte component, respectively explain.
　（形態３－Ａ（スカンジアセリア安定化ジルコニア系酸化物））
　形態３－Ａに係るＳＯＦＣ用単セルにおいて、燃料極、空気極及び固体電解質層から選ばれる少なくとも何れか１つに電解質成分として含まれるジルコニア系酸化物は、酸化スカンジウム（Ｓｃ２Ｏ３）及び酸化セリウム（ＣｅＯ２）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物Ｃを含んでいる。当該希土類酸化物Ｃは、Ｓｃ及びＣｅを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である。すなわち、希土類酸化物Ｃは、Ｙ、Ｌａ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ及びＬｕからなる群から選択される少なくとも何れか１種の元素の酸化物である。固体電解質層がこのジルコニア系酸化物を含む場合、例えば固体電解質層に主成分として含まれる電解質成分がこのジルコニア系酸化物で構成されていてもよい。この場合、固体電解質層が、安定化剤として酸化スカンジウム及び酸化セリウムが固溶されたジルコニアに、０．００３モル％以上０．５モル％未満の希土類酸化物Ｃがさらに固溶されているジルコニア系酸化物の焼結体によって形成されていてもよい。前記ジルコニア系酸化物における希土類酸化物Ｃの合計量は、０．００５モル％以上０．４モル％以下が好ましく、０．０１モル％以上０．３モル％以下がより好ましい。 (Form 3-A (scandiaceria stabilized zirconia oxide))
In the SOFC single cell according to Form 3-A, the zirconia-based oxide contained as an electrolyte component in at least one selected from the fuel electrode, the air electrode, and the solid electrolyte layer is scandium oxide (Sc 2 O 3 ) and The rare earth oxide C is stabilized with cerium oxide (CeO 2 ) and contains 0.003 mol% or more and less than 0.5 mol%. The rare earth oxide C is an oxide of at least one element selected from rare earth elements excluding Sc and Ce. That is, the rare earth oxide C is at least one selected from the group consisting of Y, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. It is an oxide of an element. When the solid electrolyte layer contains this zirconia-based oxide, for example, an electrolyte component contained as a main component in the solid electrolyte layer may be composed of this zirconia-based oxide. In this case, the solid electrolyte layer is zirconia in which 0.003 mol% or more and less than 0.5 mol% of rare earth oxide C is further solid-dissolved in zirconia in which scandium oxide and cerium oxide are dissolved as stabilizers. It may be formed of a sintered body of a system oxide. The total amount of rare earth oxide C in the zirconia-based oxide is preferably 0.005 mol% to 0.4 mol%, and more preferably 0.01 mol% to 0.3 mol%.
　実施形態１で説明したのと同様に、硫黄成分を含む雰囲気下で生じる固体電解質層の導電率の低下は、電解質成分が硫黄成分と化合物を形成したり、硫黄成分が電解質表面へ沈着・付着したりすることなどによって起こると考えられる。酸化スカンジウム（Ｓｃ２Ｏ３）及び酸化セリウム（ＣｅＯ２）で安定化されたジルコニア系酸化物において、０．００３モル％以上０．５モル％未満の範囲内で微量に含まれる希土類酸化物Ｃは、電解質成分と硫黄成分との化合物の形成や、電解質表面への硫黄成分の沈着・付着などを抑制する効果を有する。希土類酸化物Ｃの含有量が０．００３モル％未満の場合、希土類酸化物Ｃによる硫黄成分が電解質成分に及ぼす悪影響を抑制する効果が十分に発揮されず、固体電解質層が硫黄成分を含む雰囲気に曝された場合に、酸素イオン導電率の経時変化を小さく抑えることが困難となる。また、希土類酸化物Ｃの含有量が０．５モル％以上である場合、硫黄成分が電解質の表面に沈着・付着しやすくなったり、電解質成分と反応し易くなったりすることが予想される。その結果、燃料の流入が進むにつれて、固体電解質層の導電率が次第に劣化する。したがって、電解質成分を構成するジルコニア系酸化物が希土類酸化物Ｃを過剰に含んでいると、固体電解質層の導電率の経時変化が大きくなる。 In the same manner as described in the first embodiment, the decrease in the conductivity of the solid electrolyte layer that occurs in an atmosphere containing a sulfur component causes the electrolyte component to form a compound with the sulfur component, or the sulfur component to deposit and adhere to the electrolyte surface. It is thought that it happens by doing. In the zirconia-based oxide stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ), rare earth oxide C contained in a trace amount within a range of 0.003 mol% to less than 0.5 mol% Has the effect of suppressing the formation of a compound of an electrolyte component and a sulfur component, deposition and adhesion of the sulfur component to the electrolyte surface, and the like. When the content of the rare earth oxide C is less than 0.003 mol%, the effect of suppressing the adverse effect of the sulfur component due to the rare earth oxide C on the electrolyte component is not sufficiently exhibited, and the atmosphere in which the solid electrolyte layer contains the sulfur component When exposed to oxygen, it is difficult to keep the oxygen ion conductivity change with time small. Moreover, when the content of the rare earth oxide C is 0.5 mol% or more, it is expected that the sulfur component easily deposits and adheres to the surface of the electrolyte or reacts easily with the electrolyte component. As a result, as the inflow of fuel proceeds, the conductivity of the solid electrolyte layer gradually deteriorates. Accordingly, when the zirconia-based oxide constituting the electrolyte component contains the rare earth oxide C excessively, the change with time of the conductivity of the solid electrolyte layer becomes large.
　硫黄成分に起因する酸素イオン導電率の経時変化をより確実に小さく抑えるために、微量成分として含まれる希土類酸化物Ｃは、Ｙ、Ｌａ、Ｐｒ、Ｎｄ、Ｓｍ、Ｇｄ及びＹｂからなる群から選択される少なくとも何れか１種の元素の酸化物であることが好ましく、Ｙ、Ｓｍ、Ｇｄ及びＹｂからなる群から選択される少なくとも何れか１種の元素の酸化物であることがより好ましい。 The rare earth oxide C contained as a trace component is selected from the group consisting of Y, La, Pr, Nd, Sm, Gd, and Yb in order to more reliably suppress the temporal change in oxygen ion conductivity caused by the sulfur component. It is preferably an oxide of at least one element selected from the group consisting of Y, Sm, Gd, and Yb, and more preferably an oxide of at least one element selected from the group consisting of Y, Sm, Gd, and Yb.
　形態３－Ａにおけるジルコニア系酸化物では、より一層好ましくは、希土類酸化物Ｃが酸化ガドリニウム（Ｇｄ２Ｏ３）であることである。酸化ガドリニウム（Ｇｄ２Ｏ３）は、形態３－Ａにおけるジルコニア系酸化物に希土類酸化物Ｃとして含まれる場合、他の希土類酸化物の中でも特に、電解質成分と硫黄成分との化合物の形成や、電解質表面への硫黄成分の沈着・付着などを抑制する効果が高い。したがって、形態３－Ａにおけるジルコニア系酸化物が希土類酸化物Ｃとして酸化ガドリニウム（Ｇｄ２Ｏ３）を含むことにより、硫黄成分に起因する酸素イオン導電率の経時変化をより一層確実に小さく抑えることができる。また、形態３－Ａにおけるジルコニア系酸化物が酸化ガドリニウム（Ｇｄ２Ｏ３）を含む場合、その含有量は０．００３モル％以上０．２モル％以下であることが好ましい。酸化ガドリニウム（Ｇｄ２Ｏ３）の含有量が０．２モル％を超える場合、酸化ガドリニウム（Ｇｄ２Ｏ３）の含有量に見合う程度に効果を高めることができないためである。 In the zirconia-based oxide in Form 3-A, it is more preferable that the rare earth oxide C is gadolinium oxide (Gd 2 O 3 ). When gadolinium oxide (Gd 2 O 3 ) is contained in the zirconia-based oxide in Form 3-A as rare earth oxide C, among other rare earth oxides, formation of a compound of an electrolyte component and a sulfur component, Highly effective in suppressing the deposition and adhesion of sulfur components to the electrolyte surface. Therefore, when the zirconia-based oxide in Form 3-A contains gadolinium oxide (Gd 2 O 3 ) as the rare earth oxide C, the change over time in the oxygen ion conductivity caused by the sulfur component can be more reliably suppressed. Can do. In addition, when the zirconia-based oxide in Form 3-A contains gadolinium oxide (Gd 2 O 3 ), the content is preferably 0.003 mol% or more and 0.2 mol% or less. This is because when the content of gadolinium oxide (Gd 2 O 3 ) exceeds 0.2 mol%, the effect cannot be enhanced to the extent that it matches the content of gadolinium oxide (Gd 2 O 3 ).
　形態３－Ａにおけるジルコニア系酸化物が酸化ガドリニウム（Ｇｄ２Ｏ３）を含む場合、酸化イットリウム（Ｙ２Ｏ３）も希土類酸化物Ｃとしてさらに添加されることが好ましい。形態３－ＡのＳＯＦＣ用単セルが、酸化ガドリニウム（Ｇｄ２Ｏ３）と酸化イットリウム（Ｙ２Ｏ３）との両方を希土類酸化物Ｃとして含むジルコニア系酸化物を含む場合、硫黄成分が電解質成分に及ぼす悪影響を抑制する効果をさらに向上させることができる。酸化ガドリニウム（Ｇｄ２Ｏ３）と酸化イットリウム（Ｙ２Ｏ３）との両方が含まれることによる相乗効果の理由は明らかではないが、酸化イットリウム（Ｙ２Ｏ３）の含有量が０．００３モル％以上０．２モル％以下の範囲の場合に、特に優れた効果を得ることができる。 When the zirconia-based oxide in Form 3-A contains gadolinium oxide (Gd 2 O 3 ), it is preferable that yttrium oxide (Y 2 O 3 ) is further added as rare earth oxide C. When the single cell for SOFC of Form 3-A contains a zirconia-based oxide containing both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) as rare earth oxide C, the sulfur component is an electrolyte. The effect of suppressing adverse effects on the components can be further improved. Although the reason for the synergistic effect due to the inclusion of both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) is not clear, the content of yttrium oxide (Y 2 O 3 ) is 0.003. A particularly excellent effect can be obtained when the content is in the range of from mol% to 0.2 mol%.
　形態３－Ａにおけるジルコニア系酸化物は、酸化スカンジウム（Ｓｃ２Ｏ３）を、８モル％以上１５モル％以下で含んでいることが好ましく、８．５モル％以上１２モル％以下で含んでいることがより好ましく、９モル％以上１１モル％以下で含んでいることがより一層好ましい。 The zirconia-based oxide in Form 3-A preferably contains scandium oxide (Sc 2 O 3 ) in an amount of 8 mol% to 15 mol%, and contains 8.5 mol% to 12 mol%. It is more preferable that it is contained in an amount of 9 mol% or more and 11 mol% or less.
　形態３－Ａにおけるジルコニア系酸化物は、酸化セリウム（ＣｅＯ２）を０．５モル％以上２．５モル％以下で含んでいることが好ましく、０．６モル％以上２モル％以下で含んでいることがより好ましく、０．７モル％以上１．５モル％以下で含んでいることがより一層好ましい。 The zirconia-based oxide in Form 3-A preferably contains cerium oxide (CeO 2 ) in an amount of 0.5 mol% to 2.5 mol%, preferably 0.6 mol% to 2 mol%. It is more preferable that it is contained in an amount of 0.7 mol% or more and 1.5 mol% or less.
　形態３－Ａにおけるジルコニア系酸化物は、燃料極及び／又は空気極に電極組成物の一部として含まれていてもよい。このジルコニア系酸化物が燃料極及び／又は空気極に含まれる場合に得られる効果は、上述のとおりである。 The zirconia-based oxide in Form 3-A may be included in the fuel electrode and / or the air electrode as part of the electrode composition. The effects obtained when this zirconia-based oxide is contained in the fuel electrode and / or the air electrode are as described above.
　（形態３－Ｂ（スカンジア安定化ジルコニア系酸化物））
　形態３－Ｂに係るＳＯＦＣ用単セルにおいて、燃料極、空気極及び固体電解質層から選ばれる少なくとも何れか１つに電解質成分として含まれるジルコニア系酸化物は、酸化スカンジウム（Ｓｃ２Ｏ３）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物Ｄを含むジルコニア系酸化物で構成されている。当該希土類酸化物Ｄは、Ｓｃを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である。すなわち、希土類酸化物Ｄは、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ及びＬｕからなる群から選択される少なくとも何れか１種の元素の酸化物である。固体電解質層がこのジルコニア系酸化物を含む場合、例えば固体電解質層に主成分として含まれる電解質成分がこのジルコニア系酸化物で構成されていてもよい。この場合、固体電解質層が、安定化剤として酸化スカンジウムが固溶されたジルコニアに、０．００３モル％以上０．５モル％未満の希土類酸化物Ｄがさらに固溶されているジルコニア系酸化物の焼結体によって形成されていてもよい。前記ジルコニア系酸化物における希土類酸化物Ｄの合計量は、０．００５モル％以上０．４モル％以下が好ましく、０．０１モル％以上０．３モル％以下がより好ましい。 (Form 3-B (scandia-stabilized zirconia oxide))
In the SOFC single cell according to Form 3-B, the zirconia-based oxide contained as an electrolyte component in at least one selected from the fuel electrode, the air electrode, and the solid electrolyte layer is scandium oxide (Sc 2 O 3 ). It is stabilized and is composed of a zirconia-based oxide containing rare earth oxide D of 0.003 mol% or more and less than 0.5 mol%. The rare earth oxide D is an oxide of at least one element selected from rare earth elements excluding Sc. That is, the rare earth oxide D is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. It is an oxide of a seed element. When the solid electrolyte layer contains this zirconia-based oxide, for example, an electrolyte component contained as a main component in the solid electrolyte layer may be composed of this zirconia-based oxide. In this case, the solid electrolyte layer is a zirconia oxide in which 0.003 mol% or more and less than 0.5 mol% of rare earth oxide D is further dissolved in zirconia in which scandium oxide is dissolved as a stabilizer. The sintered body may be formed. The total amount of rare earth oxide D in the zirconia-based oxide is preferably 0.005 mol% or more and 0.4 mol% or less, and more preferably 0.01 mol% or more and 0.3 mol% or less.
　硫黄成分を含む雰囲気下で生じる固体電解質層の導電率の低下は、電解質成分が硫黄成分と化合物を形成したり、硫黄成分が電解質表面へ沈着・付着したりすることなどによって起こると考えられる。酸化スカンジウム（Ｓｃ２Ｏ３）で安定化されたジルコニア系酸化物において、０．００３モル％以上０．５モル％未満の範囲内で微量に含まれる希土類酸化物Ｄは、電解質成分と硫黄成分との化合物の形成や、電解質表面への硫黄成分の沈着・付着などを抑制する効果を有する。希土類酸化物Ｄの含有量が０．００３モル％未満の場合、希土類酸化物Ｄによる硫黄成分が電解質成分に及ぼす悪影響を抑制する効果が十分に発揮されず、固体電解質層が硫黄成分を含む雰囲気に曝された場合に、酸素イオン導電率の経時変化を小さく抑えることが困難となる。また、希土類酸化物Ｄの含有量が０．５モル％以上である場合、硫黄成分が電解質の表面に沈着・付着しやすくなったり、電解質成分と反応し易くなったりすることが予想される。その結果、燃料の流入が進むにつれて、固体電解質層の導電率が次第に劣化する。したがって、電解質成分を構成するジルコニア系酸化物が希土類酸化物Ｄを過剰に含んでいると、固体電解質層の導電率の経時変化が大きくなる。 It is considered that the decrease in the conductivity of the solid electrolyte layer that occurs in an atmosphere containing a sulfur component occurs due to the electrolyte component forming a compound with the sulfur component, or the sulfur component being deposited or adhered to the electrolyte surface. In the zirconia-based oxide stabilized with scandium oxide (Sc 2 O 3 ), the rare earth oxide D contained in a trace amount within the range of 0.003 mol% or more and less than 0.5 mol% includes an electrolyte component and a sulfur component. It has the effect of suppressing the formation of the compound and the deposition and adhesion of sulfur components to the electrolyte surface. When the content of the rare earth oxide D is less than 0.003 mol%, the effect of suppressing the adverse effect of the sulfur component due to the rare earth oxide D on the electrolyte component is not sufficiently exhibited, and the atmosphere in which the solid electrolyte layer contains the sulfur component When exposed to oxygen, it is difficult to keep the oxygen ion conductivity change with time small. Further, when the content of the rare earth oxide D is 0.5 mol% or more, it is expected that the sulfur component is likely to be deposited and adhered to the surface of the electrolyte, or to react with the electrolyte component. As a result, as the inflow of fuel proceeds, the conductivity of the solid electrolyte layer gradually deteriorates. Therefore, when the zirconia-based oxide constituting the electrolyte component contains the rare earth oxide D excessively, the change with time of the conductivity of the solid electrolyte layer becomes large.
　硫黄成分に起因する酸素イオン導電率の経時変化をより確実に小さく抑えるために、微量成分として含まれる希土類酸化物Ｄは、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｇｄ及びＹｂからなる群から選択される少なくとも何れか１種の元素の酸化物であることが好ましく、Ｙ、Ｃｅ、Ｓｍ、Ｇｄ及びＹｂからなる群から選択される少なくとも何れか１種の元素の酸化物であることがより好ましい。 The rare earth oxide D contained as a trace component is a group consisting of Y, La, Ce, Pr, Nd, Sm, Gd, and Yb in order to more reliably suppress the temporal change in oxygen ion conductivity caused by the sulfur component. Preferably, the oxide is an oxide of at least one element selected from the group consisting of Y, Ce, Sm, Gd, and Yb. More preferred.
　形態３－Ｂにおけるジルコニア系酸化物では、より一層好ましくは、希土類酸化物Ｄが酸化セリウム（ＣｅＯ２）であることである。酸化セリウム（ＣｅＯ２）は、形態３－Ｂにおけるジルコニア系酸化物に希土類酸化物Ｄとして含まれる場合、希土類酸化物の中でも特に、電解質成分と硫黄成分との化合物の形成や、電解質表面への硫黄成分の沈着・付着などを抑制する効果が高い。したがって、形態３－Ｂにおけるジルコニア系酸化物が希土類酸化物Ｄとして酸化セリウム（ＣｅＯ２）を含むことにより、硫黄成分に起因する酸素イオン導電率の経時変化をより一層確実に小さく抑えることができる。また、形態３－Ｂにおけるジルコニア系酸化物が酸化セリウム（ＣｅＯ２）を含む場合、その含有量は０．１モル％以上が好ましく、０．２モル％以上がより好ましい。また、形態３－Ｂにおけるジルコニア系酸化物が酸化セリウム（ＣｅＯ２）を含む場合、その含有量は０．４８モル％以下が好ましく、０．４５モル％以下がより好ましい。 In the zirconia-based oxide in Form 3-B, it is more preferable that the rare earth oxide D is cerium oxide (CeO 2 ). When cerium oxide (CeO 2 ) is contained as the rare earth oxide D in the zirconia-based oxide in Form 3-B, particularly among rare earth oxides, formation of a compound of an electrolyte component and a sulfur component, Highly effective in suppressing deposition and adhesion of sulfur components. Therefore, when the zirconia-based oxide in Form 3-B contains cerium oxide (CeO 2 ) as the rare earth oxide D, the change over time in the oxygen ion conductivity caused by the sulfur component can be more reliably suppressed. . Further, when the zirconia-based oxide in Form 3-B contains cerium oxide (CeO 2 ), its content is preferably 0.1 mol% or more, and more preferably 0.2 mol% or more. Further, when the zirconia-based oxide in Form 3-B contains cerium oxide (CeO 2 ), its content is preferably 0.48 mol% or less, and more preferably 0.45 mol% or less.
　また、形態３－Ｂにおけるジルコニア系酸化物において、希土類酸化物Ｄが酸化ガドリニウム（Ｇｄ２Ｏ３）である場合も、酸素イオン導電率の経時変化を抑制する高い効果が得られる。形態３－Ｂにおけるジルコニア系酸化物が酸化ガドリニウム（Ｇｄ２Ｏ３）を含む場合、その含有量は０．００３モル％以上０．２モル％以下であることが好ましく、０．００５モル％以上０．１モル％以下がより好ましい。 In addition, in the zirconia-based oxide in Form 3-B, when the rare earth oxide D is gadolinium oxide (Gd 2 O 3 ), a high effect of suppressing change with time in oxygen ion conductivity can be obtained. When the zirconia-based oxide in Form 3-B contains gadolinium oxide (Gd 2 O 3 ), its content is preferably 0.003 mol% or more and 0.2 mol% or less, and 0.005 mol% or more 0.1 mol% or less is more preferable.
　また、形態３－Ｂにおけるジルコニア系酸化物において、希土類酸化物Ｄが酸化イットリウム（Ｙ２Ｏ３）である場合も、酸素イオン導電率の経時変化を抑制する高い効果が得られる。形態３－Ｂにおけるジルコニア系酸化物が酸化イットリウム（Ｙ２Ｏ３）を含む場合、その含有量は０．００３モル％以上０．２モル％以下であることが好ましく、０．００５モル％以上０．１モル％以下がより好ましい。 In addition, in the zirconia-based oxide in Form 3-B, when the rare earth oxide D is yttrium oxide (Y 2 O 3 ), a high effect of suppressing change with time in oxygen ion conductivity can be obtained. When the zirconia-based oxide in Form 3-B contains yttrium oxide (Y 2 O 3 ), its content is preferably 0.003 mol% or more and 0.2 mol% or less, and 0.005 mol% or more 0.1 mol% or less is more preferable.
　形態３－Ｂにおけるジルコニア系酸化物が、酸化ガドリニウム（Ｇｄ２Ｏ３）と酸化イットリウム（Ｙ２Ｏ３）との両方を希土類酸化物Ｄとして含んでいてもよい。形態３－Ｂの固体電解質層の電解質成分が、酸化ガドリニウム（Ｇｄ２Ｏ３）と酸化イットリウム（Ｙ２Ｏ３）との両方を希土類酸化物Ｄとして含むジルコニア系酸化物で構成されることにより、硫黄成分が電解質成分に及ぼす悪影響を抑制する効果をさらに向上させることができる。酸化ガドリニウム（Ｇｄ２Ｏ３）と酸化イットリウム（Ｙ２Ｏ３）との両方が含まれることによる相乗効果の理由は明らかではないが、酸化ガドリニウム（Ｇｄ２Ｏ３）と酸化イットリウム（Ｙ２Ｏ３）との合計量が０．００３モル％以上０．２モル％以下であることが好ましく、０．００５モル％以上０．１モル％以下がより好ましい。 The zirconia-based oxide in Form 3-B may contain both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) as rare earth oxide D. The electrolyte component of the solid electrolyte layer of Form 3-B is composed of a zirconia-based oxide containing both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) as rare earth oxide D. The effect of suppressing the adverse effect of the sulfur component on the electrolyte component can be further improved. The reason for the synergistic effect due to the inclusion of both gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O 3 ) is not clear, but gadolinium oxide (Gd 2 O 3 ) and yttrium oxide (Y 2 O). 3 ) is preferably from 0.003 mol% to 0.2 mol%, more preferably from 0.005 mol% to 0.1 mol%.
　形態３－Ｂにおけるジルコニア系酸化物は、酸化スカンジウム（Ｓｃ２Ｏ３）を、４モル％以上１５モル％以下で含んでいることが好ましい。形態３－Ｂにおけるジルコニア系酸化物の結晶系が正方晶系である場合、当該ジルコニア系酸化物は酸化スカンジウム（Ｓｃ２Ｏ３）を４モル％以上６．５モル％以下で含んでいることが好ましい。形態３－Ｂにおけるジルコニア系酸化物の結晶系が立方晶系である場合、当該ジルコニア系酸化物は酸化スカンジウム（Ｓｃ２Ｏ３）を９モル％以上１３モル％以下で含んでいることが好ましく、９．５モル％以上１２モル％以下で含んでいることがより好ましく、１０モル％以上１１．５モル％以下で含んでいることがより一層好ましい。 The zirconia-based oxide in Form 3-B preferably contains scandium oxide (Sc 2 O 3 ) in an amount of 4 mol% to 15 mol%. When the crystal system of the zirconia-based oxide in Form 3-B is a tetragonal system, the zirconia-based oxide contains scandium oxide (Sc 2 O 3 ) in an amount of 4 mol% to 6.5 mol%. Is preferred. When the crystal system of the zirconia-based oxide in Form 3-B is a cubic system, the zirconia-based oxide preferably contains scandium oxide (Sc 2 O 3 ) in an amount of 9 mol% to 13 mol%. 9.5 mol% or more and 12 mol% or less, more preferably 10 mol% or more and 11.5 mol% or less.
　本実施形態のＳＯＦＣ用単セル（以下、本実施形態のＳＯＦＣ用単セルとは、形態３－ＡのＳＯＦＣ用単セル及び形態３－ＢのＳＯＦＣ用単セルの両方を指す。）のタイプは、特に制限されない。本実施形態のＳＯＦＣ用単セルの構成は、電解質支持型セル（以下、「ＥＳＣ」と記載することがある。）、燃料極支持型セル（以下、「ＡＳＣ」と記載することがある。）、空気極支持型セル（以下、「ＣＳＣ」と記載することがある。）及び金属支持型セル（以下、「ＭＳＣ」と記載することがある。）等のいずれにも適用可能である。 The type of the SOFC single cell of the present embodiment (hereinafter, the SOFC single cell of the present embodiment refers to both the single cell for SOFC of form 3-A and the single cell for SOFC of form 3-B). There is no particular restriction. The configuration of the single cell for SOFC of this embodiment is an electrolyte support cell (hereinafter sometimes referred to as “ESC”) and a fuel electrode support cell (hereinafter sometimes referred to as “ASC”). It can be applied to any of an air electrode support cell (hereinafter sometimes referred to as “CSC”) and a metal support cell (hereinafter sometimes referred to as “MSC”).
　ここでは、本実施形態のＳＯＦＣ用単セルが燃料極支持型セルの場合を例に挙げて説明する。図２に示すように、本実施形態のＳＯＦＣ用単セル２は、燃料極活性層（燃料極）２１と、空気極２２と、燃料極活性層２１と空気極２２との間に配置された固体電解質層２３と、燃料極活性層２１の固体電解質層２３と反対側の表面に設けられて、燃料極活性層２１、固体電解質層２３及び空気極２２を支持している燃料極支持基板２４と、を備えている。 Here, a case where the single cell for SOFC of this embodiment is a fuel electrode support type cell will be described as an example. As shown in FIG. 2, the SOFC single cell 2 of the present embodiment is disposed between the fuel electrode active layer (fuel electrode) 21, the air electrode 22, and the fuel electrode active layer 21 and the air electrode 22. A solid electrolyte layer 23 and a fuel electrode support substrate 24 provided on the surface of the fuel electrode active layer 21 opposite to the solid electrolyte layer 23 and supporting the fuel electrode active layer 21, solid electrolyte layer 23, and air electrode 22. And.
　燃料極支持基板２４及び燃料極活性層２１は、導電成分と骨格成分とを含む材料によって形成されている。導電成分は、燃料極支持基板２４及び燃料極活性層２１に導電性を付与するための成分である。骨格成分は、燃料極支持基板２４及び燃料極活性層２１の骨格を形成する成分であり、必要な強度を確保する上で重要な成分である。導電成分には、ＳＯＦＣ用単セルの燃料極に用いられる公知の材料を用いることができる。骨格成分には、本実施形態のジルコニア系酸化物が含まれていることが望ましい。骨格成分が、本実施形態のジルコニア系酸化物と、燃料極の骨格成分として公知である他の材料との組み合わせであってもよい。 The fuel electrode support substrate 24 and the fuel electrode active layer 21 are formed of a material containing a conductive component and a skeleton component. The conductive component is a component for imparting conductivity to the fuel electrode support substrate 24 and the fuel electrode active layer 21. The skeletal component is a component that forms the skeleton of the fuel electrode support substrate 24 and the fuel electrode active layer 21, and is an important component in securing necessary strength. As the conductive component, a known material used for the fuel electrode of the single cell for SOFC can be used. It is desirable that the skeletal component contains the zirconia-based oxide of this embodiment. The skeleton component may be a combination of the zirconia-based oxide of this embodiment and another material known as a skeleton component of the fuel electrode.
　燃料極活性層２１の厚さは、特に限定されないが、例えば５μｍ以上が望ましく、７μｍ以上がより望ましく、１０μｍ以上がさらに望ましい。また、燃料極活性層１１の厚さは、１００μｍ以下が望ましく、５０μｍ以下がより望ましく、３０μｍ以下がさらに望ましい。燃料極活性層２１の厚さが上記範囲内であれば、電極反応が効率的に行われ、燃料極支持型セルとした場合に発電性能がより良好となる。 The thickness of the fuel electrode active layer 21 is not particularly limited, but is preferably 5 μm or more, more preferably 7 μm or more, and further preferably 10 μm or more. The thickness of the anode active layer 11 is preferably 100 μm or less, more preferably 50 μm or less, and further preferably 30 μm or less. If the thickness of the fuel electrode active layer 21 is within the above range, the electrode reaction is efficiently performed, and the power generation performance becomes better when the fuel electrode support cell is used.
　燃料極支持基板２４の厚さは、特に限定されないが、例えば１００μｍ以上が望ましく、１２０μｍ以上がより望ましく、１５０μｍ以上がさらに望ましい。また、燃料極支持基板１４の厚さは、３ｍｍ以下が望ましく、２ｍｍ以下がより望ましく、１ｍｍ以下がさらに望ましく、５００μｍ以下が特に望ましい。燃料極支持基板３４の厚さが上記範囲内であれば、燃料極支持基板２４の機械的強度とガス通過性とをバランス良く両立しやすくなる。 The thickness of the fuel electrode support substrate 24 is not particularly limited, but is preferably, for example, 100 μm or more, more preferably 120 μm or more, and further preferably 150 μm or more. Further, the thickness of the fuel electrode support substrate 14 is preferably 3 mm or less, more preferably 2 mm or less, further preferably 1 mm or less, and particularly preferably 500 μm or less. If the thickness of the fuel electrode support substrate 34 is within the above range, the mechanical strength and gas permeability of the fuel electrode support substrate 24 can be easily balanced.
　固体電解質層２３は、本実施形態のジルコニア系酸化物を含むことが望ましい。例えば、固体電解質層２３は、本実施形態のジルコニア系酸化物の焼結体によって形成されていてもよい。すなわち、固体電解質層２３に含まれる電解質成分が、本実施形態のジルコニア系酸化物からなっていてもよい。あるいは、固体電解質層２３は、本実施形態のジルコニア系酸化物と、ＳＯＦＣ用の固体電解質層の材料として公知である他の材料との混合物の焼結体であってもよい。すなわち、固体電解質層２３に含まれる電解質成分が、本実施形態のジルコニア系酸化物と、ＳＯＦＣ用の固体電解質層の材料として公知である他の材料との混合物であってもよい。電解質成分がこのような混合物である場合、本実施形態のジルコニア系酸化物は、５０質量％以上含まれていることが望ましく、７０質量％以上含まれていることがより望ましい。 The solid electrolyte layer 23 desirably contains the zirconia-based oxide of the present embodiment. For example, the solid electrolyte layer 23 may be formed of the sintered body of the zirconia-based oxide of the present embodiment. That is, the electrolyte component contained in the solid electrolyte layer 23 may be made of the zirconia-based oxide of the present embodiment. Alternatively, the solid electrolyte layer 23 may be a sintered body of a mixture of the zirconia-based oxide of the present embodiment and another material known as a material for the solid electrolyte layer for SOFC. That is, the electrolyte component contained in the solid electrolyte layer 23 may be a mixture of the zirconia-based oxide of this embodiment and another material known as a material for the solid electrolyte layer for SOFC. When the electrolyte component is such a mixture, the zirconia-based oxide of the present embodiment is desirably contained in an amount of 50% by mass or more, and more desirably 70% by mass or more.
　固体電解質層２３の厚さは、特に限定されないが、例えば３μｍ以上が望ましく、４μｍ以上がより望ましく、５μｍ以上がさらに望ましい。また、固体電解質層２３の厚さは、５０μｍ以下が望ましく、３０μｍ以下がより望ましく、２０μｍ以下がさらに望ましい。固体電解質層２３の厚さが上記範囲内であれば、燃料極支持型セルとした場合に、ガスのクロスリークを防ぎつつも、発電性能がより良好となる。 The thickness of the solid electrolyte layer 23 is not particularly limited, but is preferably 3 μm or more, more preferably 4 μm or more, and further preferably 5 μm or more, for example. Further, the thickness of the solid electrolyte layer 23 is desirably 50 μm or less, more desirably 30 μm or less, and further desirably 20 μm or less. When the thickness of the solid electrolyte layer 23 is within the above range, when the fuel electrode support cell is used, the power generation performance is improved while preventing gas cross-leakage.
　空気極２２は、一般に、電子伝導性に優れ、酸化雰囲気下でも安定な、ペロブスカイト形酸化物が用いられる。具体的には、Ｌａ０．８Ｓｒ０．２ＭｎＯ３、Ｌａ０．６Ｓｒ０．４ＣｏＯ３、Ｌａ０．６Ｓｒ０．４ＦｅＯ３及びＬａ０．６Ｓｒ０．４Ｃｏ０．２Ｆｅ０．８Ｏ３等のランタンの一部をストロンチウムで置換したランタンマンガナイト、ランタンフェライト及びランタンコバルタイト等が好適に用いられる。また、空気極２２が、本実施形態のジルコニア系酸化物を含んでいてもよい。　 The air electrode 22 is generally made of a perovskite oxide that has excellent electron conductivity and is stable even in an oxidizing atmosphere. Specifically, La 0.8 Sr 0.2 MnO 3 , La 0.6 Sr 0.4 CoO 3 , La 0.6 Sr 0.4 FeO 3 and La 0.6 Sr 0.4 Co 0.2 Lanthanum manganite, lanthanum ferrite, lanthanum cobaltite, etc. in which a part of lanthanum such as Fe 0.8 O 3 is substituted with strontium are preferably used. Moreover, the air electrode 22 may contain the zirconia-type oxide of this embodiment.
　空気極２２の厚さは、特に限定されないが、例えば５μｍ以上が望ましく、７μｍ以上がより望ましく、１０μｍ以上がさらに望ましい。また、空気極１２の厚さは、８０μｍ以下が望ましく、７０μｍ以下がより望ましく、６０μｍ以下がさらに望ましい。空気極２２の厚さが上記範囲内であれば、電極反応が効率的に行われ、燃料極支持型セルとした場合に、発電性能がより良好となる。　 The thickness of the air electrode 22 is not particularly limited, but is preferably 5 μm or more, more preferably 7 μm or more, and further preferably 10 μm or more. Further, the thickness of the air electrode 12 is desirably 80 μm or less, more desirably 70 μm or less, and further desirably 60 μm or less. When the thickness of the air electrode 22 is within the above range, the electrode reaction is efficiently performed, and the power generation performance is improved when the fuel electrode support cell is used. *
　次に、ＳＯＦＣ用単セル２の製造方法について説明する。　 Next, a method for manufacturing the SOFC single cell 2 will be described. *
　本実施形態のジルコニア系酸化物を用いて固体電解質層２３等が形成される場合、まず本実施形態のジルコニア系酸化物の原料粉末が準備される。この原料粉末は、実施形態１の電解質シートに含まれるジルコニア系酸化物の原料粉末と同じ方法を利用して製造できるので、ここでは詳細な説明を省略する。 When the solid electrolyte layer 23 or the like is formed using the zirconia-based oxide of the present embodiment, first, a raw material powder of the zirconia-based oxide of the present embodiment is prepared. Since this raw material powder can be manufactured using the same method as the raw material powder of the zirconia-based oxide contained in the electrolyte sheet of Embodiment 1, detailed description is omitted here.
　ＳＯＦＣ用単セル２を製造する方法の一例は、燃料極支持基板２４、燃料極活性層２１及び固体電解質層２３を含む多層焼成体を作製する工程と、得られた多層焼成体を所定の形状に切断及び／又は打ち抜きする工程と、所定の形状に切断された多層焼成体において、燃料極活性層２１と反対側の面に空気極２２を作製する工程と、を含む方法である。　 An example of a method for manufacturing the single cell 2 for SOFC includes a step of producing a multilayer fired body including the fuel electrode support substrate 24, the fuel electrode active layer 21, and the solid electrolyte layer 23, and the obtained multilayer fired body is formed into a predetermined shape. And the step of producing the air electrode 22 on the surface opposite to the fuel electrode active layer 21 in the multilayer fired body cut into a predetermined shape. *
　多層焼成体は、
（１）燃料極支持基板２４用のグリーンシート上に、燃料極活性層２１用のスクリーン印刷等で形成された層やグリーンシート層などのグリーン層と、固体電解質層２３用のスクリーン印刷等で形成された層やグリーンシート層などのグリーン層とが順に積み重ねられた積層体を形成した後、これら全体を一括してあるいは順次焼成する方法、
又は、
（２）燃料極支持基板２４用のグリーンシートを焼成して燃料極支持基板２４を作製し、その上に燃料極活性層２１用のグリーン層と、固体電解質層２３用のグリーン層とが順に積み重ねられた積層体を形成した後、これらを焼成する方法、
を用いて作製できる。ここでは、（１）の方法を例に挙げて、多層焼成体の作製方法を説明する。　 The multilayer fired body
(1) On a green sheet for the anode support substrate 24, a layer formed by screen printing for the anode active layer 21, a green layer such as a green sheet layer, and screen printing for the solid electrolyte layer 23, etc. A method of firing the whole or all at once after forming a laminate in which green layers such as formed layers and green sheet layers are sequentially stacked,
Or
(2) The green sheet for the fuel electrode support substrate 24 is fired to produce the fuel electrode support substrate 24, and the green layer for the fuel electrode active layer 21 and the green layer for the solid electrolyte layer 23 are sequentially formed thereon. A method of firing these after forming stacked laminates,
Can be used. Here, the method for producing a multilayer fired body will be described by taking the method (1) as an example.
　まず、燃料極支持基板２４用のグリーンシートを準備する。燃料極支持基板２４用のグリーンシートは、原料粉末（導電成分の粉末及び骨格成分の粉末）と、バインダー及び溶剤とを混合し、さらに必要に応じて気孔形成剤、分散剤及び可塑剤等を添加してスラリーを調製し、このスラリーをドクターブレード法、カレンダーロール法、押出し法等の任意の方法で所定の厚さを有するシート状に成形し、これを乾燥させて溶剤を揮発除去することによって、得られる。導電成分及び骨格成分として使用可能な材料は、上記のとおりである。また、気孔形成剤、バインダー、溶剤、分散剤及び可塑剤等は、ＳＯＦＣの燃料極支持基板の製造方法において公知となっている気孔形成剤、バインダー、溶剤、分散剤及び可塑剤等の中から適宜選択できる。　 First, a green sheet for the fuel electrode support substrate 24 is prepared. The green sheet for the fuel electrode support substrate 24 is a mixture of raw material powder (conductive component powder and skeletal component powder), a binder and a solvent, and further, if necessary, a pore forming agent, a dispersing agent, a plasticizer and the like. Add slurry to prepare a slurry, and form the slurry into a sheet having a predetermined thickness by any method such as doctor blade method, calender roll method, extrusion method, etc., and dry this to volatilize and remove the solvent. Is obtained by The materials that can be used as the conductive component and the skeleton component are as described above. Further, the pore-forming agent, binder, solvent, dispersant, plasticizer, and the like can be selected from pore-forming agents, binders, solvents, dispersants, plasticizers, and the like that are known in the manufacturing method of the SOFC fuel electrode support substrate. It can be selected as appropriate. *
　燃料極支持基板２４用のグリーンシート上に、燃料極活性層２１用のペーストを用いて、燃料極活性層２１用のグリーン層が形成される。燃料極活性層２１用のペーストは、原料粉末（導電成分の粉末及び骨格成分の粉末）と、バインダー及び溶剤とを混合し、さらに必要に応じて気孔形成剤、分散剤及び可塑剤等を添加することによって、調製される。このペーストを燃料極支持基板２４用のグリーンシート上に、スクリーン印刷等の方法を用いて塗布し、これを乾燥させることによって、燃料極活性層２１用のグリーン層が形成される。導電成分及び骨格成分として使用可能な材料は、上記のとおりである。また、気孔形成剤、バインダー、溶剤、分散剤及び可塑剤等は、ＳＯＦＣの燃料極活性層の製造方法において公知となっている気孔形成剤、バインダー、溶剤、分散剤及び可塑剤等の中から適宜選択できる。 The green layer for the fuel electrode active layer 21 is formed on the green sheet for the fuel electrode support substrate 24 using the paste for the fuel electrode active layer 21. The paste for the anode active layer 21 is a mixture of raw material powder (conductive component powder and skeletal component powder), a binder and a solvent, and further, a pore forming agent, a dispersing agent, a plasticizer and the like are added as necessary. To be prepared. This paste is applied on a green sheet for the fuel electrode support substrate 24 by using a method such as screen printing, and dried to form a green layer for the fuel electrode active layer 21. The materials that can be used as the conductive component and the skeleton component are as described above. The pore-forming agent, binder, solvent, dispersant, plasticizer, etc. are selected from among pore-forming agents, binders, solvents, dispersants, plasticizers, etc. known in the SOFC fuel electrode active layer manufacturing method. It can be selected as appropriate.
　燃料極活性層２１用のグリーン層の上に、固体電解質層２３用のペーストを用いて、固体電解質層２３用のグリーン層が形成される。固体電解質層２３用のペーストは、少なくとも電解質成分の原料となる粉末と溶媒とを混合して作製される。電解質成分として使用可能な材料は、上記のとおりである。固体電解質層２３用のペーストに用いられる溶媒には、ＳＯＦＣの固体電解質層のペーストを作製する際に用いられている公知の材料を使用できる。固体電解質層２３用のペーストに、電解質成分の原料となる粉末及び溶媒に加えて、バインダー、分散剤、可塑剤、界面活性剤、消泡剤等を添加してもよい。バインダー、分散剤、可塑剤、界面活性剤、消泡剤等は、ＳＯＦＣの固体電解質層の製造方法において公知となっているバインダー、分散剤、可塑剤、界面活性剤、消泡剤等の中から適宜選択できる。　 The green layer for the solid electrolyte layer 23 is formed on the green layer for the fuel electrode active layer 21 using the paste for the solid electrolyte layer 23. The paste for the solid electrolyte layer 23 is prepared by mixing at least a powder that is a raw material for the electrolyte component and a solvent. The materials that can be used as the electrolyte component are as described above. As the solvent used for the paste for the solid electrolyte layer 23, a known material used in preparing a solid electrolyte layer paste of SOFC can be used. A binder, a dispersant, a plasticizer, a surfactant, an antifoaming agent, and the like may be added to the paste for the solid electrolyte layer 23 in addition to the powder and solvent that are the raw materials for the electrolyte component. Binders, dispersants, plasticizers, surfactants, antifoaming agents, etc. are among the binders, dispersants, plasticizers, surfactants, antifoaming agents, etc. known in the SOFC solid electrolyte layer manufacturing method. Can be selected as appropriate. *
　固体電解質層２３用のグリーン層上に、必要であればバリア層用のグリーン層を形成してもよい。バリア層用のグリーン層も、燃料極活性層２１及び固体電解質層２３と同様に、バリア層を構成する原料粉末を含むペーストを調製し、それを固体電解質層２３用のグリーン層上に塗布し、乾燥させることによって形成できる。 If necessary, a green layer for a barrier layer may be formed on the green layer for the solid electrolyte layer 23. Similarly to the fuel electrode active layer 21 and the solid electrolyte layer 23, the green layer for the barrier layer is prepared by preparing a paste containing the raw material powder constituting the barrier layer and applying it to the green layer for the solid electrolyte layer 23. It can be formed by drying.
　燃料極支持基板２４用のグリーンシート上に、燃料極活性層２１用のグリーン層と、固体電解質層２３用のグリーン層と、バリア層を設ける構成の場合はバリア層用のグリーン層と、が順に積み重ねられることによって形成された積層体が、一括してあるいは順次焼成される。積層体の焼成温度は、特に限定されないが、１１００℃以上が望ましく、１２００℃以上がより望ましく、１２５０℃以上がさらに望ましい。また、焼成温度は、１５００℃以下が望ましく、１４００℃以下がより望ましく、１３５０℃以下がさらに望ましい。また、焼成時の焼成時間は、特に限定されないが、０．１時間以上が望ましく、０．５時間以上がより望ましく、１時間以上がさらに望ましい。また、焼成時間は、１０時間以下が望ましく、７時間以下がより望ましく、５時間以下がさらに望ましい。　 On the green sheet for the anode support substrate 24, there are a green layer for the anode active layer 21, a green layer for the solid electrolyte layer 23, and a green layer for the barrier layer in the case of providing a barrier layer. Laminates formed by sequentially stacking are fired collectively or sequentially. The firing temperature of the laminate is not particularly limited, but is preferably 1100 ° C. or higher, more preferably 1200 ° C. or higher, and further preferably 1250 ° C. or higher. The firing temperature is preferably 1500 ° C. or lower, more preferably 1400 ° C. or lower, and further preferably 1350 ° C. or lower. The firing time during firing is not particularly limited, but is preferably 0.1 hours or longer, more preferably 0.5 hours or longer, and even more preferably 1 hour or longer. The firing time is preferably 10 hours or less, more preferably 7 hours or less, and even more preferably 5 hours or less. *
　以上のような方法によって、多層焼成体が得られる。次に、得られた多層焼成体を所定の形状に切断及び／又は打ち抜きする。 A multilayer fired body is obtained by the method as described above. Next, the obtained multilayer fired body is cut and / or punched into a predetermined shape.
　次に、所定の形状に切断された多層焼成体において、燃料極支持基板２４と反対側の面上に、空気極２２を作製する。空気極２２用のペーストを用いて空気極２２用のグリーン層を形成し、それを焼成することによって空気極２２が作製される。空気極２２用のペーストは、空気極２２を構成する原料粉末、バインダー及び溶媒と、必要により分散剤及び可塑剤等とを共に均一に混合することによって、調製される。空気極２２を構成する材料として使用可能な材料は、上記のとおりである。また、バインダー、溶剤、分散剤及び可塑剤等は、ＳＯＦＣの空気極の製造方法において公知となっているバインダー、溶剤、分散剤及び可塑剤等の中から適宜選択できる。調製したペーストを、多層焼成体上にスクリーン印刷等により塗布し、乾燥させることによって、空気極２２用のグリーン層が形成される。これを焼成することによって、空気極２２が作製される。焼成温度は、特に限定されないが、８００℃以上が望ましく、８５０℃以上がより望ましく、９５０℃以上がさらに望ましい。また、焼成温度は、１４００℃以下が望ましく、１３５０℃以下がより望ましく、１３００℃以下がさらに望ましい。また、焼成時の焼成時間は、特に限定されないが、０．１時間以上が望ましく、０．５時間以上がより望ましく、１時間以上がさらに望ましい。また、焼成時間は、１０時間以下が望ましく、７時間以下がより望ましく、５時間以下がさらに望ましい。 Next, in the multilayer fired body cut into a predetermined shape, the air electrode 22 is produced on the surface opposite to the fuel electrode support substrate 24. A green layer for the air electrode 22 is formed using the paste for the air electrode 22, and the air electrode 22 is produced by firing the green layer. The paste for the air electrode 22 is prepared by uniformly mixing together the raw material powder, the binder, and the solvent that constitute the air electrode 22 and, if necessary, the dispersant, the plasticizer, and the like. The materials that can be used as the material constituting the air electrode 22 are as described above. The binder, solvent, dispersant, plasticizer, and the like can be appropriately selected from binders, solvents, dispersants, plasticizers, and the like that are known in the SOFC air electrode manufacturing method. The prepared paste is applied on the multilayer fired body by screen printing or the like and dried to form a green layer for the air electrode 22. By baking this, the air electrode 22 is produced. Although a calcination temperature is not specifically limited, 800 degreeC or more is desirable, 850 degreeC or more is more desirable, and 950 degreeC or more is still more desirable. The firing temperature is preferably 1400 ° C. or lower, more preferably 1350 ° C. or lower, and further preferably 1300 ° C. or lower. The firing time during firing is not particularly limited, but is preferably 0.1 hours or longer, more preferably 0.5 hours or longer, and even more preferably 1 hour or longer. The firing time is preferably 10 hours or less, more preferably 7 hours or less, and even more preferably 5 hours or less.
　以上のような方法により、ＳＯＦＣ用単セル２を製造することができる。 The SOFC single cell 2 can be manufactured by the method as described above.
　なお、ここでは燃料極支持型セルを例に挙げて説明したが、電解質支持型セル、空気極支持型セル及び金属支持型セルの場合であっても、同様に、本実施形態のジルコニア系酸化物を燃料極、空気極及び／又は固体電解質層に用いることが可能である。 Here, the fuel electrode support type cell has been described as an example. However, even in the case of an electrolyte support type cell, an air electrode support type cell, and a metal support type cell, the zirconia-based oxidation of the present embodiment is similarly applied. It is possible to use the object for the fuel electrode, the air electrode and / or the solid electrolyte layer.
　（実施形態４）
　本発明のＳＯＦＣの実施形態について説明する。本実施形態のＳＯＦＣは、実施形態２で説明した電解質支持型セル、又は、実施形態３で説明したＳＯＦＣ用単セルを備えている。本実施形態のＳＯＦＣは、例えば、積層されて互いに直列接続（スタック化）された複数の単セルを備えている。このとき、隣接する単セルを互いに電気的に接続すると同時に、マニホールドを介して燃料極と空気極とにそれぞれ燃料ガスと酸化剤ガスとを適正に分配する目的で、セル間に金属またはセラミックスからなるセパレータが配置される。なお、セパレータは、インタコネクタとも呼ばれる。 (Embodiment 4)
An embodiment of the SOFC of the present invention will be described. The SOFC of this embodiment includes the electrolyte-supported cell described in Embodiment 2 or the SOFC single cell described in Embodiment 3. The SOFC of this embodiment includes, for example, a plurality of single cells that are stacked and connected in series (stacked). At this time, the adjacent single cells are electrically connected to each other, and at the same time, the fuel gas and the oxidant gas are properly distributed to the fuel electrode and the air electrode through the manifold, respectively. A separator is arranged. The separator is also called an interconnector.
　本実施形態のＳＯＦＣに用いられる単セルは、実施形態２及び３で説明したとおり、硫黄成分を含む雰囲気に曝されても耐久性が低下しにくい。したがって、本実施形態のＳＯＦＣも、同様に、硫黄成分を含む雰囲気に曝されても耐久性が低下しにくい。これにより、本実施形態のＳＯＦＣは、都市ガスを改質することで生成した水素が燃料として用いられる場合であって、しかもその燃料に硫黄成分が含まれる可能性がある場合であっても、耐久性の低下を小さく抑えることができる。例えば、都市ガスを燃料に利用するＳＯＦＣシステムにおいて、燃料電池外に改質器を設けて都市ガスを改質するシステムの場合、改質器と共に脱硫装置も設けられる場合が多い。しかし、都市ガスをＳＯＦＣ内で直接改質する内部改質型のＳＯＦＣが用いられるシステムでは、脱硫装置が設けられない場合もある。したがって、本実施形態のＳＯＦＣの構成は、特に、内部改質型のＳＯＦＣとした際に優れた効果を奏する。 As described in the second and third embodiments, the single cell used in the SOFC of the present embodiment is less likely to be deteriorated in durability even when exposed to an atmosphere containing a sulfur component. Therefore, the durability of the SOFC of the present embodiment is not easily lowered even when exposed to an atmosphere containing a sulfur component. Thereby, the SOFC of the present embodiment is a case where hydrogen generated by reforming city gas is used as a fuel, and even if the fuel may contain a sulfur component, A decrease in durability can be kept small. For example, in an SOFC system that uses city gas as fuel, in a system that reforms city gas by providing a reformer outside the fuel cell, a desulfurization device is often provided along with the reformer. However, in a system in which an internal reforming SOFC that directly reforms city gas in the SOFC is used, a desulfurization apparatus may not be provided. Therefore, the configuration of the SOFC of the present embodiment has an excellent effect particularly when an internal reforming SOFC is used.
　次に、本発明について、実施例を用いて具体的に説明する。なお、本発明は、以下に示す実施例によって何ら限定されるものではない。また、以下、例えば、「ｘＳｃ ｙＣｅ ｚＧｄ ＳＺ」との表記は、ｘモル％の酸化スカンジウム（Ｓｃ２Ｏ３）と、ｙモル％の酸化セリウム（ＣｅＯ２）と、ｚモル％の酸化ガドリニウム（Ｇｄ２Ｏ３）と、残部の酸化ジルコニウム（ＺｒＯ２）とを含んだ安定化ジルコニアを意味する。 Next, the present invention will be specifically described using examples. In addition, this invention is not limited at all by the Example shown below. Further, hereinafter, for example, the notation “xSc yCe zGd SZ” refers to x mol% scandium oxide (Sc 2 O 3 ), y mol% cerium oxide (CeO 2 ), and z mol% gadolinium oxide ( Gd 2 O 3 ) and the remaining zirconium oxide (ZrO 2 ) means stabilized zirconia.
（１）ジルコニア系酸化物粉末の調製
　Ｓｃ２Ｏ３が１０モル％、ＣｅＯ２が１モル％、微量の希土類酸化物としてのＧｄ２Ｏ３が０．１モル％、微量の希土類酸化物としてのＹ２Ｏ３が０．０５モル％、残部がＺｒＯ２となるように、オキシ塩化ジルコニウムと、塩化スカンジウムと、塩化セリウムと、微量の塩化ガドリニウム及び塩化イットリウムとの混合水溶液を調製した。混合水溶液は、ＺｒＯ２が０．２モル／Ｌとなるように調製された。攪拌機付槽型反応器に純水３００ｍＬを入れ、さらにアンモニア水を加えて、ｐＨ８．５とした。これに上記混合水溶液を液速５０ｍＬ／分の割合で、また、アンモニア水（２８質量％水溶液）を５０ｍＬ／時の割合で、定量ポンプを用いてそれぞれ攪拌下注加した。反応器内の液量がほぼ一定となるように別の定量ポンプで反応液を排出しながら、中和共沈反応を連続的に行った。反応中ｐＨが８．５±０．２の範囲になるように、該混合水溶液およびアンモニア水の液速を微調整しながら中和共沈反応を行った。排出液中の水酸化物を濾過により母液から分離し、次いで水洗を繰り返すことによって塩化アンモニウムを除去した。得られた水酸化物をｎ－ブタノール中に分散し、溶液温度が１０５℃になるまで常圧蒸留を行うことにより脱水を行った。次いで、この脱水された水酸化物を含むｎ－ブタノール分散液を噴霧乾燥させ、流動性の良い粉末を得た。この粉末を１０００℃で１時間焼成することにより、凝集塊の認められない、比表面積が９ｍ２／ｇの１０Ｓｃ１Ｃｅ０．１Ｇｄ０．０５ＹＳＺ粉末（表１の試料１）を得た。 (1) Preparation of zirconia-based oxide powder Sc 2 O 3 is 10 mol%, CeO 2 is 1 mol%, Gd 2 O 3 as a trace amount of rare earth oxide is 0.1 mol%, and a trace amount of rare earth oxide A mixed aqueous solution of zirconium oxychloride, scandium chloride, cerium chloride, and a small amount of gadolinium chloride and yttrium chloride was prepared so that Y 2 O 3 in the mixture was 0.05 mol% and the balance was ZrO 2 . The mixed aqueous solution was prepared so that ZrO 2 was 0.2 mol / L. 300 mL of pure water was put into a tank reactor with a stirrer, and ammonia water was further added to adjust the pH to 8.5. The above mixed aqueous solution was poured into the mixture at a rate of 50 mL / min, and ammonia water (28 mass% aqueous solution) was added at a rate of 50 mL / hr with stirring using a metering pump. The neutralization coprecipitation reaction was continuously performed while discharging the reaction solution with another metering pump so that the amount of the solution in the reactor was almost constant. A neutralization coprecipitation reaction was carried out while finely adjusting the liquid speed of the mixed aqueous solution and aqueous ammonia so that the pH was in the range of 8.5 ± 0.2 during the reaction. The hydroxide in the effluent was separated from the mother liquor by filtration and then the ammonium chloride was removed by repeated washing with water. The obtained hydroxide was dispersed in n-butanol and dehydrated by performing atmospheric distillation until the solution temperature reached 105 ° C. Next, the n-butanol dispersion containing the dehydrated hydroxide was spray-dried to obtain a powder with good fluidity. This powder was fired at 1000 ° C. for 1 hour to obtain a 10Sc1Ce0.1Gd0.05YSZ powder (sample 1 in Table 1) having a specific surface area of 9 m 2 / g and no agglomerates.
　試料２～１６のジルコニア系酸化物粉末については、表１に示す試料２～１６の組成となるように、所定量のオキシ塩化ジルコニウムと、塩化スカンジウムと、塩化セリウムと、さらに希土類酸化物としての微量の塩化ガドリニウム、塩化イットリウム、硝酸サマリウム、硝酸ネオジウム及び硝酸イッテルビウムと、硝酸アルミニウムとを適宜用いて混合水溶液を調製し、試料１のジルコニア系酸化物と同様の方法でジルコニア系酸化物粉末を得た。 With respect to the zirconia oxide powders of Samples 2 to 16, a predetermined amount of zirconium oxychloride, scandium chloride, cerium chloride, and a rare earth oxide were prepared so as to have the compositions of Samples 2 to 16 shown in Table 1. Prepare a mixed aqueous solution using a small amount of gadolinium chloride, yttrium chloride, samarium nitrate, neodymium nitrate, ytterbium nitrate, and aluminum nitrate, and obtain a zirconia-based oxide powder in the same manner as the zirconia-based oxide of Sample 1. It was.
　また、試料１７～３１のジルコニア系酸化物粉末については、表２に示す試料１７～３１の組成になるように、所定量のオキシ塩化ジルコニウムと、塩化スカンジウムと、さらに希土類酸化物としての微量の塩化セリウム、塩化ガドリニウム、塩化イットリウム、硝酸サマリウム、硝酸ネオジウム及び硝酸イッテルビウムと、硝酸アルミニウムとを適宜を用いて混合水溶液を調製し、試料１のジルコニア系酸化物と同様の方法でジルコニア系酸化物粉末を得た。 The zirconia-based oxide powders of Samples 17 to 31 have a predetermined amount of zirconium oxychloride, scandium chloride, and a trace amount of rare earth oxide so as to have the compositions of Samples 17 to 31 shown in Table 2. Prepare a mixed aqueous solution using cerium chloride, gadolinium chloride, yttrium chloride, samarium nitrate, neodymium nitrate, ytterbium nitrate, and aluminum nitrate as appropriate, and use the zirconia oxide powder in the same manner as the zirconia oxide of sample 1 Got.
（２）ジルコニア系酸化物粉末の組成分析
　試料１～３１の各ジルコニア系酸化物粉末の組成分析については、ジルコニア（ＺｒＯ２）と、スカンジア（Ｓｃ２Ｏ３）を除くその他の全希土類酸化物の希土類元素と、その他の元素との定量は、ＩＣＰ（Ｔｈｅｒｍｏ　Ｆｉｓｈｅｒ　ＳＣＩＥＮＴＩＦＩＣ社製、型式：ｉ　ＣＡＰ　６５００　Ｄｕｏ）で３回行い、スカンジアの定量はＸＲＦ（ＢＲＵＫＥＲ　ＡＸＳ社製、型式：Ｓ８　ＴＩＧＥＲ）で３回行い、それぞれの平均値から、各粉末中の含有量を計算した。なお、希土類酸化物の元素以外にＡｌ２Ｏ３、ＳｉＯ２、ＴｉＯ２、Ｆｅ２Ｏ３、Ｎａ２Ｏ、ＣａＯ２及びＣｌも不純物として検出されるが、例えば、ＳｉＯ２量はジルコニア粉末に対して０．００５質量％以下、ＳｉＯ２を除く不純物はそれぞれ０．００１質量％以下と極微量であった。各ジルコニア系酸化物粉末の組成計算法について、以下に述べる。 (2) Composition analysis of zirconia-based oxide powder Regarding composition analysis of each zirconia-based oxide powder of Samples 1 to 31, all other rare earth oxides except zirconia (ZrO 2 ) and scandia (Sc 2 O 3 ) Quantification of rare earth elements and other elements in ICP (Thermo Fisher SCIENTIFIC, model: iCAP 6500 Duo) was performed three times, and Scandia was quantified in XRF (manufactured by BRUKER AXS, model: S8 TIGER). It carried out 3 times and calculated content in each powder from each average value. In addition to the rare earth oxide elements, Al 2 O 3 , SiO 2 , TiO 2 , Fe 2 O 3 , Na 2 O, CaO 2 and Cl are also detected as impurities. For example, the amount of SiO 2 is in the zirconia powder. 0.005 mass% for less impurities excluding SiO 2 was 0.001 mass% as trace amount, respectively. The composition calculation method of each zirconia-based oxide powder will be described below.
［ジルコニア系酸化物粉末の組成計算法］
（Ｉ）各希土類元素分析値の平均値を用いて、Ｘ２Ｏ３酸化物（Ｘは希土類元素を示す）に換算した値を、ジルコニア系酸化物粉末中の各希土類元素酸化物の含有量（質量％）とした。ただし、酸化セリウムはＣｅＯ２とした。
（II）スカンジア（Ｓｃ２Ｏ３）の分析値の平均値を、ジルコニア系酸化物粉末中のスカンジア含有量（質量％）とした。
（III）ジルコニア系酸化物粉末が、ジルコニア（ＺｒＯ２）と、各希土類元素の酸化物（Ｘ２Ｏ３）と、スカンジア（Ｓｃ２Ｏ３）とのみからなると仮定し、各希土類酸化物（Ｘ２Ｏ３）含有量（質量％）とスカンジア含有量（質量％）との合計（質量％）を求め、その残部をジルコニアの含有量（質量％）とした。
（IV）（III）で得られた質量基準での含有量（質量％）より、ジルコニア系酸化物粉末の単位質量に含まれる、各希土類元素の酸化物（Ｘ２Ｏ３、ＣｅＯ２）と、スカンジア（Ｓｃ２Ｏ３）と、ジルコニア（ＺｒＯ２）とのそれぞれのモル数を計算する。
（Ｖ）各希土類元素の酸化物（Ｘ２Ｏ３、ＣｅＯ２）及びスカンジア（Ｓｃ２Ｏ３）のそれぞれのモル数を、各希土類元素の酸化物（Ｘ２Ｏ３、ＣｅＯ２）、スカンジア（Ｓｃ２Ｏ３）及びジルコニア（ＺｒＯ２）のモル数の合計で除することにより得られた値を、各希土類元素の酸化物（Ｘ２Ｏ３）及びスカンジア（Ｓｃ２Ｏ３）のジルコニア系酸化物粉末に対する含有量（モル％）とした。 [Composition calculation method of zirconia oxide powder]
(I) The content of each rare earth element oxide in the zirconia-based oxide powder obtained by converting the value converted to X 2 O 3 oxide (X represents a rare earth element) using the average value of each rare earth element analysis value (Mass%). However, cerium oxide was CeO 2.
(II) The average value of the analysis value of scandia (Sc 2 O 3 ) was defined as the scandia content (% by mass) in the zirconia-based oxide powder.
(III) It is assumed that the zirconia-based oxide powder is composed only of zirconia (ZrO 2 ), oxides of each rare earth element (X 2 O 3 ), and scandia (Sc 2 O 3 ). The total (mass%) of the X 2 O 3 ) content (mass%) and the scandia content (mass%) was determined, and the remainder was defined as the zirconia content (mass%).
(IV) From the content (mass%) on a mass basis obtained in (III), each rare earth element oxide (X 2 O 3 , CeO 2 ) contained in the unit mass of the zirconia-based oxide powder and The number of moles of each of scandia (Sc 2 O 3 ) and zirconia (ZrO 2 ) is calculated.
(V) The number of moles of each rare earth element oxide (X 2 O 3 , CeO 2 ) and scandia (Sc 2 O 3 ) is changed to each rare earth element oxide (X 2 O 3 , CeO 2 ), scandia. The value obtained by dividing by the total number of moles of (Sc 2 O 3 ) and zirconia (ZrO 2 ) is the zirconia of each rare earth oxide (X 2 O 3 ) and scandia (Sc 2 O 3 ). The content (mol%) relative to the system oxide powder was used.
（３）グリーンシートの作製
　電解質成分として、上記のようにして調製した表１、表２に示す組成を有する試料１～３１のジルコニア系酸化物粉末を用い、それぞれのジルコニア粉末１００質量部に対し、メタクリル系共重合体からなるバインダー（数平均分子量；１００，０００、ガラス転移温度；－８℃）を固形分換算で１６質量部、分散剤としてソルビタン酸トリオレート２質量部、可塑剤としてジブチルフタレート３質量部、溶剤としてトルエン／イソプロパノール（質量比＝３／２）の混合溶剤５０質量部を、ジルコニアボールが装入されたナイロンミルに入れ、４０時間ミリングしてスラリーを調製した。得られたスラリーを、碇型の攪拌機を備えた内容積５０Ｌのジャケット付丸底円筒型減圧脱泡容器へ移し、攪拌機を３０ｒｐｍの速度で回転させながら、ジャケット温度４０℃とし、減圧（約４～２１ｋＰａ）下で濃縮脱泡し、２５℃での粘度を３Ｐａ・ｓに調整して、塗工用スラリーとした。この塗工用スラリーを、ドクターブレード法によりポリエチレンテレフタレート（ＰＥＴ）フィルム上に連続的に塗工した。次いで、４０℃、８０℃、１１０℃で乾燥させることによって、長尺のグリーンテープを得た。このグリーンテープを打抜き刃（中山紙器材料社製）で約３８ｍｍφの円形に切断し、さらにＰＥＴフィルムから剥離して、それぞれのジルコニアグリーンシートを作製した。 (3) Production of Green Sheet As the electrolyte component, zirconia-based oxide powders of Samples 1 to 31 having the compositions shown in Tables 1 and 2 prepared as described above were used, and 100 parts by mass of each zirconia powder. , A binder composed of a methacrylic copolymer (number average molecular weight; 100,000, glass transition temperature: −8 ° C.) in terms of solid content, 16 parts by mass, 2 parts by mass of sorbitan acid trioleate as a dispersant, and dibutyl as a plasticizer 3 parts by mass of phthalate and 50 parts by mass of a mixed solvent of toluene / isopropanol (mass ratio = 3/2) as a solvent were placed in a nylon mill charged with zirconia balls and milled for 40 hours to prepare a slurry. The obtained slurry was transferred to a jacketed round bottom cylindrical vacuum degassing vessel having an internal volume of 50 L equipped with a bowl-shaped stirrer, and the jacket temperature was adjusted to 40 ° C. while rotating the stirrer at a speed of 30 rpm. The slurry was concentrated and degassed under a pressure of ˜21 kPa, and the viscosity at 25 ° C. was adjusted to 3 Pa · s to obtain a slurry for coating. This coating slurry was continuously coated on a polyethylene terephthalate (PET) film by a doctor blade method. Next, a long green tape was obtained by drying at 40 ° C., 80 ° C., and 110 ° C. This green tape was cut into a circular shape of about 38 mmφ with a punching blade (manufactured by Nakayama Paper Equipment Co., Ltd.) and further peeled from the PET film to prepare each zirconia green sheet.
（４）電解質シートの作製
　上記（３）で得たそれぞれのジルコニアグリーンシートを用い、当該グリーンシートの上下をウネリ最大高さが１０μｍの９９．５％アルミナ多孔質板（気孔率：３０％）で挟んで、当該グリーンシート５枚を含む積層体を作製した。この積層体を電気炉に搬入して脱脂した後、１４２０℃で３時間加熱焼成し、３０ｍｍφ、厚さ０．２８ｍｍの安定化ジルコニア電解質シートを作製した。得られたそれぞれの電解質シートの相対密度（アルキメデス法で測定された密度／理論密度）は、９８．１～９９．５％の範囲であった。 (4) Production of electrolyte sheet Using each of the zirconia green sheets obtained in (3) above, a 99.5% alumina porous plate (porosity: 30%) with a maximum height of 10 μm above and below the green sheet. A laminate including the five green sheets was produced. After carrying this laminated body into an electric furnace and degreasing | defatting, it heat-baked at 1420 degreeC for 3 hours, and produced the stabilized zirconia electrolyte sheet of 30 mm diameter and thickness 0.28 mm. The relative density (density measured by Archimedes method / theoretical density) of each obtained electrolyte sheet was in the range of 98.1 to 99.5%.
（５）ＳＯＦＣ用単セルの作製
　（ｉ）ＥＳＣの作製
　上記（４）で得た電解質シート（試料１～３、６～９、１２、１３、１５（１６）、１９～２５、２８、２９及び３１の電解質シート）のそれぞれについて、一方の面に燃料極を、他方の面に空気極を形成し、ＳＯＦＣ用のＥＳＣを作製した。詳しくは、３０ｍｍφで厚さが０．２８ｍｍのそれぞれの電解質シートの一方面において、周縁部３ｍｍ幅の領域を除く約２４ｍｍφの領域に、塩基性炭酸ニッケルを熱分解して得た酸化ニッケル粉末（ｄ５０（メジアン径）：０．９μｍ）６５質量部と市販の８ＹＳＺ系粉末（第一稀元素社製、ＨＳＹ－８．０）３５質量部とを含む燃料極ペーストをスクリーン印刷で塗布し、乾燥させた。また、それぞれの電解質シートの他方面にも同様に、周縁部３ｍｍ幅の領域を除く約２４ｍｍφの領域に、市販のストロンチウムドープドランタンマンガン複合酸化物粉末（ＡＧＣセイミケミカル社製：Ｌａ０．６Ｓｒ０．４ＭｎＯ３）８０質量部と市販の２０モル％ガドリニアドープセリア粉末（ＡＧＣセイミケミカル社製：ＧＤＣ２０）２０質量部とを含む空気極ペーストを、スクリーン印刷で塗布し、乾燥させた。次いで、両面に電極を塗布したそれぞれの電解質シートを、１３００℃で３時間焼成して、厚さが４０μｍの燃料極層と厚さが３０μｍの空気極層が形成された３層構造の３０ｍｍφの、表３および４に示す各ＥＳＣを作製した。 (5) Production of single cell for SOFC (i) Production of ESC Electrolyte sheets obtained in (4) above (Samples 1 to 3, 6 to 9, 12, 13, 15 (16), 19 to 25, 28, 29 And 31 electrolyte sheets), a fuel electrode was formed on one surface, and an air electrode was formed on the other surface, thereby producing an ESC for SOFC. Specifically, a nickel oxide powder obtained by thermally decomposing basic nickel carbonate in a region of about 24 mmφ excluding a region having a width of 3 mm on the one side of each electrolyte sheet having a thickness of 30 mmφ and a thickness of 0.28 mm ( d50 (median diameter): 0.9 μm) A fuel electrode paste containing 65 parts by mass and 35 parts by mass of commercially available 8YSZ-based powder (manufactured by Daiichi Rare Element Co., Ltd., HSY-8.0) was applied by screen printing and dried. I let you. Similarly, on the other side of each electrolyte sheet, a commercially available strontium-doped lanthanum manganese composite oxide powder (manufactured by AGC Seimi Chemical Co., Ltd .: La 0.6 An air electrode paste containing 80 parts by mass of Sr 0.4 MnO 3 ) and 20 parts by mass of a commercially available 20 mol% gadolinia dope ceria powder (manufactured by AGC Seimi Chemical Co., Ltd .: GDC20) was applied by screen printing and dried. Next, each electrolyte sheet coated with electrodes on both sides was baked at 1300 ° C. for 3 hours to form a 30-mmφ 30-mmφ three-layer structure in which a fuel electrode layer having a thickness of 40 μm and an air electrode layer having a thickness of 30 μm were formed. Each ESC shown in Tables 3 and 4 was prepared.
　（ii）ＡＳＣの作製
　（ａ）燃料極支持基板の作成
　市販の３ＹＳＺ系粉末（第一稀元素社製：ＨＳＹ－３．０）５０質量部と、市販の酸化ニッケル粉末（キシダ化学社製、ｄ５０（メジアン径）：０．６μｍ）５０質量部との合計１００質量部に対し、上記（３）で用いたものと同様のバインダー（固形分換算で１５質量部）、可塑剤（２質量部）及び混合溶剤（５０質量部）と、気孔形成剤として市販のトウモロコシ澱粉５質量部とを、ジルコニアボールが装入されたボールミルポットに入れ、約６０ｒｐｍで２０時間混練することにより燃料極支持基板用スラリーを調製した。このスラリーを減圧脱泡機に入れて、スラリー中に浸された碇型攪拌羽根を１０ｒｐｍの回転速度で２４時間回転させながら濃縮脱泡し、２５℃での粘度を８Ｐａ・ｓに調整して塗工用スラリーとした。この塗工用スラリーを、ドクターブレード法によりＰＥＴフィルム上に連続的に塗工し、次いで、４０℃、８０℃、１１０℃で乾燥させて長尺のグリーンテープを得た。このグリーンテープを打抜き刃で約３８ｍｍφに切断して、さらにＰＥＴフィルムから剥離して、３ＹＳＺ／ＮｉＯグリーンシートを作製した。このグリーンシートを、グリーンシートの周縁がはみ出さない様に、ウネリ最大高さが１０μｍの９９．５％ニッケルアルミネート多孔質板（気孔率：３０％）で挟み、厚さ２０ｍｍの棚板（東海高熱工業社製、商品名「ダイヤライトＤＣ－Ｍ」）上に載置し、１３５０℃で焼成した。これにより、３０ｍｍφの円形で、厚さが０．５ｍｍの燃料極支持基板が作製された。得られた燃料極支持基板に、上記（５）（ｉ）で用いた燃料極ペーストを燃料極支持基板の周縁から３ｍｍ幅の周縁部を除いてスクリーン印刷で塗布し、乾燥させた後、１３００℃で焼成することによって、燃料極活性層付燃料極支持基板を作製した。 (Ii) Production of ASC (a) Production of fuel electrode support substrate 50 parts by mass of commercially available 3YSZ-based powder (Daiichi Rare Element Co., Ltd .: HSY-3.0) and commercially available nickel oxide powder (manufactured by Kishida Chemical Co., Ltd.) d50 (median diameter): 0.6 μm) For 100 parts by mass in total with 50 parts by mass, the same binder as used in (3) above (15 parts by mass in terms of solid content), plasticizer (2 parts by mass) ) And a mixed solvent (50 parts by mass) and 5 parts by mass of commercially available corn starch as a pore-forming agent are placed in a ball mill pot charged with zirconia balls and kneaded at about 60 rpm for 20 hours, thereby supporting the fuel electrode support substrate. A slurry was prepared. This slurry is put in a vacuum degassing machine, and the vertical stirring blade immersed in the slurry is concentrated and degassed while rotating at a rotation speed of 10 rpm for 24 hours, and the viscosity at 25 ° C. is adjusted to 8 Pa · s. A slurry for coating was obtained. This coating slurry was continuously applied onto a PET film by a doctor blade method, and then dried at 40 ° C., 80 ° C., and 110 ° C. to obtain a long green tape. This green tape was cut to about 38 mmφ with a punching blade, and further peeled from the PET film to produce a 3YSZ / NiO green sheet. This green sheet is sandwiched between 99.5% nickel aluminate porous plates (porosity: 30%) with a maximum ridge height of 10 μm so that the peripheral edge of the green sheets does not protrude, and a shelf plate with a thickness of 20 mm ( The product was placed on a product name “Dialite DC-M” manufactured by Tokai Koetsu Kogyo Co., Ltd. and fired at 1350 ° C. As a result, a fuel electrode support substrate having a circular shape of 30 mmφ and a thickness of 0.5 mm was produced. The fuel electrode paste used in (5) (i) above was applied to the obtained fuel electrode support substrate by screen printing except for the 3 mm wide periphery from the periphery of the fuel electrode support substrate, dried, and then 1300 A fuel electrode supporting substrate with a fuel electrode active layer was produced by firing at 0 ° C.
　（ｂ）電解質層の作製
　上記（１）で得た１０Ｓｃ１Ｃｅ０．１ＧｄＳＺ粉末（試料２）、１０Ｓｃ１Ｃｅ０．１Ｇｄ０．０５ＹＳＺ粉末（試料１）及び１０Ｓｃ１ＣｅＳＺ粉末（試料１５，１６）それぞれ２５質量部に、α－テルピネオール３０質量部とエチルアルコール１００質量部とを混合した後、バインダーとしてのエチルセルロース１．５質量部と分散剤としてソルビタン酸トリオレート１質量部とを添加・混合・攪拌して、３つの電解質層用スラリーを得た。各電解質膜用スラリーを、上記（５）（ii）（ａ）で作製された燃料極活性層付燃料極支持基板の表面（燃料極活性層の表面）に塗布し、乾燥させた。スラリーの塗布及び乾燥を４回繰りかえした後、１３２０℃で３時間焼成して、燃料極活性層の上に電解質層を形成し、３つの燃料極支持型ハーフセル（１０Ｓｃ１Ｃｅ０．１ＧｄＳＺ電解質層を備えたハーフセル、１０Ｓｃ１Ｃｅ０．１Ｇｄ０．０５ＹＳＺ電解質層を備えたハーフセル、１０Ｓｃ１ＣｅＳＺ電解質層を備えたハーフセル）を作製した。 (B) Preparation of electrolyte layer 10Sc1Ce0.1GdSZ powder (sample 2) obtained in (1) above, 10Sc1Ce0.1Gd0.05YSZ powder (sample 1) and 10Sc1CeSZ powder (samples 15 and 16) were added to 25 parts by mass of α- After mixing 30 parts by mass of terpineol and 100 parts by mass of ethyl alcohol, 1.5 parts by mass of ethyl cellulose as a binder and 1 part by mass of sorbitan acid trioleate as a dispersing agent were added, mixed and stirred to form three electrolyte layers. A slurry was obtained. Each slurry for electrolyte membrane was apply | coated to the surface (surface of a fuel electrode active layer) of the fuel electrode active layer provided fuel electrode active layer produced by said (5) (ii) (a), and was dried. After applying and drying the slurry four times, the slurry was fired at 1320 ° C. for 3 hours to form an electrolyte layer on the anode active layer, and provided with three anode supported half cells (10Sc1Ce0.1GdSZ electrolyte layer) A half cell with a 10Sc1Ce0.1Gd0.05YSZ electrolyte layer and a half cell with a 10Sc1CeSZ electrolyte layer) were produced.
　（ｃ）空気極層の作製
　上記（５）（ii）（ｂ）で作製した各燃料極支持型ハーフセルの電解質層の表面に、上記（５）（ｉ）で用いた空気極ペーストをスクリーン印刷で塗布して乾燥させた。その後、１３００℃で焼成して、電解質層の上に空気極層を形成し、表５に示す３種のＡＳＣを作製した。 (C) Production of air electrode layer Screen printing of the air electrode paste used in (5) (i) above on the surface of the electrolyte layer of each fuel electrode supported half cell produced in (5), (ii) and (b) above. And dried. Then, it baked at 1300 degreeC, the air electrode layer was formed on the electrolyte layer, and three types of ASC shown in Table 5 were produced.
　（iii）ＭＳＣの作製
　板厚０．３ｍｍの多孔質フェライト系ステンレス鋼（１７％Ｃｒ－Ｆｅ）からなる金属基板の表面に、上記（５）（ｉ）で用いた燃料極ペーストをスクリーン印刷で塗布して、乾燥させた。その後、水素還元雰囲気中において１２５０℃で焼成して、金属基板上に燃料極層を形成した。この燃料極層の上に、ＳＰＤ法（熱スプレー分解法）によって、Ｇｄを含む電解質粉末（上記（１）で得た１０Ｓｃ１Ｃｅ０．１ＧｄＳＺ粉末（試料２）とＧｄを含まない電解質粉末（上記（１）で得た１０Ｓｃ１ＣｅＳＺ粉末（試料１５，１６））を用いて、それぞれを５μｍの厚さに成膜して電解質層を形成した。さらにその上に、市販のストロンチウムドープドランタン鉄コバルト複合酸化物（Ｌａ０．６Ｓｒ０．４Ｃｏ０．２Ｆｅ０．８Ｏ３）の粉末を溶射によって３０μｍの厚さに積層することによって空気極層を形成し、表６に示す２種のＭＳＣを作製した。 (Iii) Production of MSC The electrode paste used in (5) (i) above was screen printed on the surface of a metal substrate made of porous ferritic stainless steel (17% Cr—Fe) having a plate thickness of 0.3 mm. It was applied and dried. Then, it baked at 1250 degreeC in hydrogen reduction atmosphere, and formed the fuel electrode layer on the metal substrate. On this fuel electrode layer, electrolyte powder containing Gd (10Sc1Ce0.1GdSZ powder (sample 2) obtained in (1) above) and electrolyte powder not containing Gd (above (1) are obtained by SPD (thermal spray decomposition). 10Sc1CeSZ powders (samples 15 and 16)) obtained in step 1) were formed to a thickness of 5 μm to form an electrolyte layer, on which a commercially available strontium-doped lanthanum iron cobalt complex oxide was formed. An air electrode layer was formed by laminating powder of (La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 ) to a thickness of 30 μm by thermal spraying, and two types of MSCs shown in Table 6 were formed. Produced.
（６）評価試験
　（ｉ）電解質シートの酸素イオン導電率
　上記（３）で作製したグリーンシートを、それぞれ１４２０℃で３時間加熱焼成し、幅１０ｍｍ×長さ５０ｍｍの短冊状電解質シートを作製した。それぞれの相対密度は表１及び２に示すとおりである。 (6) Evaluation test (i) Oxygen ion conductivity of electrolyte sheet The green sheets prepared in (3) above were each heated and fired at 1420 ° C. for 3 hours to prepare strip-shaped electrolyte sheets having a width of 10 mm and a length of 50 mm. . Respective relative densities are as shown in Tables 1 and 2.
　得られた短冊状電解質シートをテストピースとし、８００℃に保持した電気炉中で、ターシャリーブチルメルカプタン（硫黄化合物）を１０ｐｐｍ含有する空気（以下、硫黄成分含有空気）を流通させながら、１００時間後、１０００時間後及び２０００時間後、また、試料１、２、１５、２０、２８及び３１についてはさらに３０００時間経過後の、テストピースの酸素イオン導電率を測定した。 The obtained strip-shaped electrolyte sheet was used as a test piece, and in an electric furnace maintained at 800 ° C., air containing 10 ppm of tertiary butyl mercaptan (sulfur compound) (hereinafter, sulfur component-containing air) was circulated for 100 hours. Thereafter, the oxygen ion conductivity of the test piece was measured after 1000 hours and 2000 hours, and for Samples 1, 2, 15, 20, 28, and 31 after 3000 hours had elapsed.
　具体的には、図３に示すように、テストピース３１に１ｃｍ間隔で４ヵ所に直径０．２ｍｍの金線３２ａ～３２ｄを巻付け、金ペーストを塗ってから１００℃で乾燥・固定して電流・電圧端子とし、金線３２ａ、３２ｄがテストピース３１に密着する様に、金線３２ａ、３２ｄを巻いたテストピース３１の両端をアルミナ板３３で挟み、その上から約５００ｇの荷重３４をかけた状態で８００℃に保持し、外側の２端子（金線３２ａ、３２ｄ）に０．１ｍＡの一定電流を流し、内側の２端子（金線３２ｂ、３２ｃ）の電圧をデジタルマルチメーター（アドバンテスト社製、商品名「ＴＲ６８４５型」）（図示せず）を使用し、直流４端子法で測定した。また、リード線（図示せず）にも金線を用いた。 Specifically, as shown in FIG. 3, gold wires 32 a to 32 d having a diameter of 0.2 mm are wound around 4 pieces at 1 cm intervals around a test piece 31, coated with gold paste, dried and fixed at 100 ° C. A current / voltage terminal is used, and both ends of the test piece 31 wound with the gold wires 32a and 32d are sandwiched between alumina plates 33 so that the gold wires 32a and 32d are in close contact with the test piece 31, and a load 34 of about 500 g is applied from above. The temperature is kept at 800 ° C., a constant current of 0.1 mA is applied to the outer two terminals ( gold wires 32a and 32d), and the voltage of the inner two terminals ( gold wires 32b and 32c) is changed to a digital multimeter (Advantest). (Trade name “TR6845 type”) (not shown) was used, and the measurement was performed by the direct current four-terminal method. Also, a gold wire was used for a lead wire (not shown).
　なお、テストピースは、管状電気炉に載置したガラス管の中央部に位置するように配置された。このガラス管両端の一方から他方へ硫黄成分含有空気を連続的に流通することによって、テストピースが常に硫黄成分含有空気に暴露される状態とした。 In addition, the test piece was disposed so as to be located at the center of the glass tube placed on the tubular electric furnace. By continuously circulating the sulfur component-containing air from one end of the glass tube to the other, the test piece was always exposed to the sulfur component-containing air.
　酸素イオン導電率の耐久安定性（導電率の低下率）は、硫黄成分含有空気に曝される前のテストピースの導電率（初期導電率）と、硫黄成分含有空気に所定時間曝された後のテストピースの導電率（所定時間後の導電率）との測定結果を用いて、下記式によって求めた。
導電率の低下率＝［（初期導電率－所定時間後の導電率）／初期導電率］×１００（％） The durability stability of oxygen ion conductivity (conductivity decrease rate) is determined by the test piece conductivity (initial conductivity) before exposure to sulfur component-containing air and after exposure to sulfur component-containing air for a predetermined time. Using the measurement result with the electrical conductivity of the test piece (conductivity after a predetermined time), the following test was performed.
Rate of decrease in conductivity = [(initial conductivity−conductivity after a predetermined time) / initial conductivity] × 100 (%)
　各電解質シートの導電率の低下率の結果は、表１及び表２されている。 Tables 1 and 2 show the results of the decrease rate of the conductivity of each electrolyte sheet.
　なお、試料１６の電解質シートについての導電率の低下率の結果は、硫黄成分含有空気によって導電率が低下することを確認するための参考例として、試料１５と同じグリーンシートを用いて作製されたテストピースを用いて、上記評価試験方法においてテストピースが暴露される空気を硫黄成分含有空気から硫黄成分を含有しない空気へ変更した場合の結果である。 In addition, the result of the rate of decrease in conductivity for the electrolyte sheet of Sample 16 was prepared using the same green sheet as Sample 15 as a reference example for confirming that the conductivity is decreased by the sulfur component-containing air. It is a result at the time of changing the air which a test piece is exposed in the said evaluation test method from the sulfur component containing air to the air which does not contain a sulfur component using a test piece.
　表１及び２に示すように、１００時間経過後の導電率の低下率は、１０Ｓｃ１Ｃｅ１ＡｌＳＺ電解質シート（試料１４）と９Ｓｃ１ＡｌＳＺ電解質シート（試料３０）とでは２％以上であるが、その他の電解質シートでは１．７％以下で大きな差は確認されなかった。 As shown in Tables 1 and 2, the rate of decrease in conductivity after 100 hours is 2% or more in the 10Sc1Ce1AlSZ electrolyte sheet (sample 14) and the 9Sc1AlSZ electrolyte sheet (sample 30), but in other electrolyte sheets, A large difference was not confirmed at 1.7% or less.
　しかし、２０００時間経過後では、本発明の電解質シートの要件を満たす電解質シート、すなわち、表１に示す、Ｓｃ２Ｏ３及びＣｅＯ２で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物Ａを含むジルコニア系酸化物で構成されている電解質シート（試料１～１１の電解質シート（実施例））、及び、表２に示す、Ｓｃ２Ｏ３で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物Ｂを含むジルコニア系酸化物で構成されている電解質シート（試料１７～２７の電解質シート（実施例））の導電率の低下率は、いずれも８％未満であったのに対し、本発明の電解質シートの要件を満たさない試料１２～１５及び２８～３１の電解質シート（比較例）の導電率の低下率は、いずれも８％以上であった。このように、本発明の電解質シートの要件を満たす電解質シートは、２０００時間経過後の導電率の低下率が小さく、さらに３０００時間経過後では導電率の低下率の差がさらに大きくなった。この結果から、本発明の電解質シートは、硫黄成分含有雰囲気下において、酸素イオン導電率の経時変化が小さいということが確認された。 However, after 2000 hours, the electrolyte sheet satisfying the requirements of the electrolyte sheet of the present invention, that is, stabilized with Sc 2 O 3 and CeO 2 shown in Table 1, and 0.003 mol% or more and 0.5 An electrolyte sheet composed of zirconia-based oxides containing less than mol% rare earth oxide A (electrolyte sheets of Examples 1 to 11 (Examples)), and stabilized with Sc 2 O 3 shown in Table 2 And the conductivity of an electrolyte sheet (an electrolyte sheet (Example) of Samples 17 to 27) made of zirconia-based oxide containing rare earth oxide B of 0.003 mol% or more and less than 0.5 mol%. While the decrease rate was less than 8%, the decrease rate of the conductivity of the electrolyte sheets (Comparative Examples) of Samples 12 to 15 and 28 to 31 that did not satisfy the requirements of the electrolyte sheet of the present invention was Less than 8% It was on. Thus, the electrolyte sheet satisfying the requirements of the electrolyte sheet of the present invention has a small decrease in conductivity after 2000 hours, and further has a larger difference in decrease in conductivity after 3000 hours. From this result, it was confirmed that the electrolyte sheet of the present invention has a small change with time in the oxygen ion conductivity in an atmosphere containing a sulfur component.
　また、１０Ｓｃ１Ｃｅ０．１ＧｄＳＺ電解質シート（試料２）の低下率と、１０Ｓｃ１Ｃｅ０．１Ｇｄ０．０５ＹＳＺ電解質シート（試料１）の低下率とを比較すると、酸化ガドリニウム（Ｇｄ２Ｏ３）に加えて酸化イットリウム（Ｙ２Ｏ３）をさらに含む電解質シートは、酸化イットリウム（Ｙ２Ｏ３）を含まない電解質シートよりも、１０００時間～３０００時間経過後の導電率の低下率が小さかった。この結果から、酸化ガドリニウム（Ｇｄ２Ｏ３）と酸化イットリウム（Ｙ２Ｏ３）とを共に含む電解質シートは、酸化イットリウム（Ｙ２Ｏ３）を含まない電解質シートよりも、酸素イオン導電率の経時変化を抑制する効果が高いことが確認された。 Further, when the decrease rate of the 10Sc1Ce0.1GdSZ electrolyte sheet (sample 2) and the decrease rate of the 10Sc1Ce0.1Gd0.05YSZ electrolyte sheet (sample 1) are compared, in addition to gadolinium oxide (Gd 2 O 3 ), yttrium oxide (Y further electrolyte sheet containing 2 O 3), rather than the electrolyte sheet containing no yttrium oxide (Y 2 O 3), was small rate of decrease in conductivity after 1000 hours to 3000 hours. From this result, the electrolyte sheet containing both and gadolinium oxide (Gd 2 O 3) and yttrium oxide (Y 2 O 3), rather than the electrolyte sheet containing no yttrium oxide (Y 2 O 3), oxygen ion conductivity It was confirmed that the effect of suppressing the change with time was high.
　なお、同じ１０Ｓｃ１ＣｅＳＺ電解質シートを用いて測定された、暴露される空気中に硫黄成分が含まれている場合の導電率の低下率と、硫黄成分が含まれていない場合の低下率とを比較すると（試料１５と試料１６の電解質シートの導電率の低下率を比較すると）、本発明者が見出した、「硫黄成分含有雰囲気下では、従来の固体電解質層では酸素イオン導電率の経時変化が大きくなる」、という課題の存在が確認できる。 In addition, when using the same 10Sc1CeSZ electrolyte sheet, the decrease rate of conductivity when the sulfur component is contained in the exposed air is compared with the decrease rate when the sulfur component is not included. (Comparing the rate of decrease in the conductivity of the electrolyte sheets of Sample 15 and Sample 16), the present inventor found, “Under the sulfur component-containing atmosphere, the time-dependent change in oxygen ion conductivity is large in the conventional solid electrolyte layer. It can be confirmed that there is a problem "
　（ii）電解質シートの３点曲げ強度
　上記（６）（ｉ）と同じテストピースを２０本用いて、ＪＩＳ Ｒ１６０１に準拠して３点曲げ強度を測定した。この測定は、３点曲げ強度試験用治具を取り付けた万能材料試験装置（インストロン社製；型式４３０１）を用いて行った。スパンは２０ｍｍとし、クロスヘッド速度は０．５ｍｍ／分とした。そして、各測定値の平均値を計算し、これを３点曲げ強度とした。その結果を表１及び２にまとめて示す。 (Ii) Three-point bending strength of electrolyte sheet Three-point bending strength was measured based on JIS R1601 using 20 test pieces identical to (6) and (i) above. This measurement was performed using a universal material testing apparatus (Instron; model 4301) equipped with a three-point bending strength test jig. The span was 20 mm and the crosshead speed was 0.5 mm / min. And the average value of each measured value was calculated, and this was made into 3 point | piece bending strength. The results are summarized in Tables 1 and 2.
　（iii）電解質シートの結晶相
　上記の直径３０ｍｍφで厚さ０．２８ｍｍの各電解質シートについて、Ｘ線回折測定を行った。この測定は、理学電器社製の「ＲＵ－３０００」を用いて行った。Ｘ線はＣｕＫα１（５０ｋＶ／３００ｍＡ）とし、広角ゴニオメータ及び湾曲結晶モノクロメータを用いて、２θ＝２５°～７０°の範囲で測定した。そして、立方晶に対応したピークとともに、菱面体晶に特徴的な２θ＝３０．６°などのピーク、単斜晶に特徴的な２θ＝２８．２°などのピーク、及び正方晶に特徴的な２θ＝３０．２°などのピークを観察した。なお、立方晶のメインピーク［（１１１）面］は、２θ＝３０．５°付近に現れる。そのため、上記菱面体晶のメインピーク［（１０１）面］や正方晶のメインピーク［（１１１）面］は、立方晶のメインピークと重なり確認が困難な場合がある。そこで、菱面体晶の確認は、立方晶のピークに影響され難い２θ＝５１．３°付近のピークの有無で行った。なお、このときに観察されたピークの半価幅は１°以下であった。観察結果を表１及び２にまとめて示す。 (Iii) Crystal phase of electrolyte sheet X-ray diffraction measurement was performed on each electrolyte sheet having a diameter of 30 mm and a thickness of 0.28 mm. This measurement was performed using “RU-3000” manufactured by Rigaku Corporation. The X-ray was CuKα1 (50 kV / 300 mA), and was measured in the range of 2θ = 25 ° to 70 ° using a wide-angle goniometer and a curved crystal monochromator. In addition to peaks corresponding to cubic crystals, peaks such as 2θ = 30.6 ° characteristic of rhombohedral crystals, peaks such as 2θ = 28.2 ° characteristic of monoclinic crystals, and tetragonal crystals are characteristic. Peaks such as 2θ = 30.2 ° were observed. The cubic main peak [(111) plane] appears around 2θ = 30.5 °. Therefore, the rhombohedral main peak [(101) plane] and the tetragonal main peak [(111) plane] may be difficult to confirm with the cubic main peak. Therefore, the confirmation of rhombohedral crystal was performed by the presence or absence of a peak in the vicinity of 2θ = 51.3 ° which is not easily affected by the peak of the cubic crystal. The half width of the peak observed at this time was 1 ° or less. The observation results are summarized in Tables 1 and 2.
　（iv）発電特性
　表３及び４に示すＥＳＣ（セル番号：ＥＳＣ－１～ＥＳＣ－２０）、表５に示すＡＳＣ（セル番号：ＡＳＣ－１～ＡＳＣ－３）、さらに、表６に示すＭＳＣ（セル番号：ＭＳＣ－１、ＭＳＣ－２）の各セルを、各々図４に示す公知の単セル発電評価装置を用いて、１００時間、１０００時間及び２０００時間経過後の電圧（Ｖ）を測定した。また、セル番号ＥＳＣ－１、ＥＳＣ－２、ＥＳＣ－１０、ＥＳＣ－１４、ＥＳＣ－１８及びＥＳＣ－１９のＥＳＣについては、３０００時間経過後の電圧（Ｖ）も測定した。図４中、４１は電気炉、４２はジルコニア製外筒管、４３はジルコニア製内筒管、４４は金リード線、４５は固体電解質層、４６はシール材、４８は空気極、４７は燃料極を示す。なお、ＥＳＣの場合は作動温度が８５０℃、ＡＳＣの場合は作動温度が７５０℃、ＭＳＣの場合は作動温度が７００℃であった。また、電圧測定器としてはアドバンテスト社製の商品名「ＴＲ６８４５」を用い、電流電圧発生器としては高砂製作所社製の商品名「ＧＰＯ１６－２０Ｒ」を使用した。燃料極側に燃料ガスとしてターシャリーブチルメルカプタンを１０ｐｐｍ含有する水素を１リットル／分、空気極側に酸化剤として空気を１リットル／分流通下、０．３Ａ／ｃｍ２の一定電流を通電させながら運転を行った。 (Iv) Power generation characteristics ESCs (cell numbers: ESC-1 to ESC-20) shown in Tables 3 and 4, ASCs (cell numbers: ASC-1 to ASC-3) shown in Table 5, and MSCs shown in Table 6 Measure the voltage (V) of each cell (cell number: MSC-1, MSC-2) after 100 hours, 1000 hours and 2000 hours using the known single cell power generation evaluation apparatus shown in FIG. did. For the ESCs of cell numbers ESC-1, ESC-2, ESC-10, ESC-14, ESC-18 and ESC-19, the voltage (V) after 3000 hours was also measured. In FIG. 4, 41 is an electric furnace, 42 is a zirconia outer tube, 43 is a zirconia inner tube, 44 is a gold lead wire, 45 is a solid electrolyte layer, 46 is a sealing material, 48 is an air electrode, and 47 is a fuel. Show poles. In the case of ESC, the operating temperature was 850 ° C., in the case of ASC, the operating temperature was 750 ° C., and in the case of MSC, the operating temperature was 700 ° C. In addition, the product name “TR6845” manufactured by Advantest Corporation was used as the voltage measuring device, and the product name “GPO16-20R” manufactured by Takasago Seisakusho was used as the current voltage generator. A constant current of 0.3 A / cm 2 was applied to the fuel electrode side under a flow of 1 liter / min of hydrogen containing 10 ppm of tertiary butyl mercaptan as a fuel gas and air as an oxidant on the air electrode side. While driving.
　セル発電特性の低下率は、１００時間後の電圧に対する所定時間後の電圧の変化率を測定し、下記式によって求めた。結果は、表３～６に示されている。
発電特性の低下率＝［（１００時間後の電圧－所定時間経過後の電圧）／（１００時間後の電圧）］×１００（％） The rate of decrease in cell power generation characteristics was determined by measuring the rate of change in voltage after a predetermined time with respect to the voltage after 100 hours, and calculating the rate by the following equation. The results are shown in Tables 3-6.
Reduction rate of power generation characteristics = [(Voltage after 100 hours−Voltage after lapse of predetermined time) / (Voltage after 100 hours)] × 100 (%)
　表３に示す、本発明の単セルの要件を満たすセル、すなわち、固体電解質層に、Ｓｃ２Ｏ３及びＣｅＯ２で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物Ａを含むジルコニア系酸化物で構成されている電解質シートが用いられているＥＳＣ（ＥＳＣ－１～ＥＳＣ－７（実施例））は、その発電特性の低下率が、表３に示すように、２０００時間経過後でも１４％未満であった。これに対し、本発明の単セルの要件を満たさないＥＳＣ－８～ＥＳＣ１０のＥＳＣ（比較例）では、発電特性の低下率が１６％以上であった。本発明の単セルの要件を満たすセルと満たさないセルとの発電特性の低下率の差は、３０００時間経過後ではますます大きくなり、発電特性の低下率で５％以上になった。 The cells satisfying the requirements of the single cell of the present invention shown in Table 3, that is, the solid electrolyte layer, stabilized with Sc 2 O 3 and CeO 2 and not less than 0.003 mol% and less than 0.5 mol% Table 3 shows the rate of decrease in power generation characteristics of ESCs (ESC-1 to ESC-7 (Examples)) in which electrolyte sheets composed of zirconia-based oxides including rare earth oxide A are used. Thus, even after 2000 hours, it was less than 14%. On the other hand, in the ESC-8 to ESC10 (comparative examples) that do not satisfy the requirements of the single cell of the present invention, the rate of decrease in power generation characteristics was 16% or more. The difference in the rate of decrease in power generation characteristics between cells that satisfy the requirements of the single cell of the present invention and cells that do not satisfy the requirement became larger after 3000 hours, and the rate of decrease in power generation characteristics reached 5% or more.
　表４に示す、本発明の単セルの要件を満たすセル、すなわち、固体電解質層に、Ｓｃ２Ｏ３で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物Ｂを含むジルコニア系酸化物で構成されている電解質シートが用いられているＥＳＣ（ＥＳＣ－１１～ＥＳＣ－１７（実施例））は、その発電特性の低下率は、表４に示すように、２０００時間経過後でも１５％未満であった。これに対し、本発明の単セルの要件を満たさないＥＳＣ－１９及びＥＳＣ２０のＥＳＣ（比較例）では、発電特性の低下率が１５％以上であった。なお、ＥＳＣ－１８では、２０００時間経過後の発電特性の低下率が低く抑えられているが、これは、１０００～２０００時間の間にＥＳＣ－１８のＥＳＣの評価に用いられた燃料ガスへの硫黄成分の供給に不備があったためであると考えられる。２０００～３０００時間の間では硫黄成分の供給に問題がなかったため、ＥＳＣ－１８のＥＳＣは、３０００時間経過後にその導電率の低下率がＥＳＣ－１９と同程度の２０％以上になった。すなわち、本発明の単セルの要件を満たすセルと満たさないセルとの発電特性の低下率の差は、３０００時間経過後では、発電特性の低下率で５％以上になった。 A cell satisfying the requirements of the single cell of the present invention shown in Table 4, that is, a rare earth oxide of 0.003 mol% or more and less than 0.5 mol% that is stabilized with Sc 2 O 3 in the solid electrolyte layer ESCs (ESC-11 to ESC-17 (examples)) in which an electrolyte sheet composed of a zirconia-based oxide containing B is used are shown in Table 4. Even after 2000 hours, it was less than 15%. In contrast, in ESC-19 and ESC20 (comparative examples) that do not satisfy the requirements of the single cell of the present invention, the rate of decrease in power generation characteristics was 15% or more. In ESC-18, the rate of decrease in power generation characteristics after 2000 hours is kept low. This is due to the fuel gas used for ESC evaluation of ESC-18 between 1000 and 2000 hours. This is thought to be because there was a defect in the supply of sulfur components. Since there was no problem with the supply of sulfur components between 2000 and 3000 hours, the ESC-18 ESC had a decrease rate of conductivity of 20% or more, which was about the same as that of ESC-19 after 3000 hours. That is, the difference in the rate of decrease in power generation characteristics between cells that satisfy the requirements of the single cell of the present invention and cells that do not satisfy the requirement was 5% or more in terms of the rate of decrease in power generation characteristics after 3000 hours.
　これらの結果から、硫黄成分含有雰囲気下における電極への影響を加味しても、本発明の電解質シートを用いたＥＳＣ、すなわち本発明の電解質支持型セルは、発電特性の低下率が抑制されることが判る。 From these results, even when the influence on the electrode in a sulfur component-containing atmosphere is taken into account, the ESC using the electrolyte sheet of the present invention, that is, the electrolyte-supported cell of the present invention, suppresses the rate of decrease in power generation characteristics. I understand that.
　表５に示すＡＳＣ及び表６に示すＭＳＣの発電特性の低下率も、本発明の単セルの要件を満たすセルと満たさないセルとの発電特性の低下率の差は、２０００時間経過でいずれも５％以上になった。 The rate of decrease in the power generation characteristics of the ASC shown in Table 5 and the MSC shown in Table 6 is also the difference in the rate of decrease in the power generation characteristics between the cells that satisfy the requirements of the single cell of the present invention and the cells that do not satisfy the requirements. It became 5% or more.
　以上の結果から、本発明の単セルは、硫黄成分含有雰囲気下において優れた耐久性を示すといえる。 From the above results, it can be said that the single cell of the present invention exhibits excellent durability in a sulfur component-containing atmosphere.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
　本発明のＳＯＦＣ用電解質シートは、例えば都市ガス等の硫黄化合物が含まれる燃料が利用される場合であっても、耐久性の低下を小さく抑えることができる。したがって、本発明のＳＯＦＣ用電解質シートは、例えば都市ガス等を燃料に利用する家庭用ＳＯＦＣの電解質層としても、好適に利用できる。また、本発明のＳＯＦＣ用単セル及びＳＯＦＣは、燃料に硫黄化合物が含まれる場合であっても、耐久性の低下を小さく抑えることができるので、例えば都市ガス等を燃料に利用するＳＯＦＣとして好適に利用できる。
 
  The SOFC electrolyte sheet of the present invention can suppress a decrease in durability even when a fuel containing a sulfur compound such as city gas is used. Therefore, the electrolyte sheet for SOFC of the present invention can be suitably used as an electrolyte layer for household SOFC that uses city gas or the like as fuel. In addition, the SOFC single cell and SOFC of the present invention can be used as a SOFC that uses city gas or the like as the fuel, for example, because it can suppress a decrease in durability even when the fuel contains a sulfur compound. Available to:

Claims (20)

  1. 　電解質成分を含み、
    　前記電解質成分が、酸化スカンジウム（Ｓｃ２Ｏ３）及び酸化セリウム（ＣｅＯ２）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物を含むジルコニア系酸化物で構成されており、
    　前記希土類酸化物は、Ｓｃ及びＣｅを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である、
    固体酸化物形燃料電池用電解質シート。     Including electrolyte components,
    The electrolyte component is a zirconia-based oxide that is stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ) and contains a rare earth oxide of 0.003 mol% or more and less than 0.5 mol%. Configured,
    The rare earth oxide is an oxide of at least one element selected from rare earth elements excluding Sc and Ce.
    Electrolyte sheet for solid oxide fuel cell.
  2. 　前記ジルコニア系酸化物は、８モル％以上１５モル％以下の酸化スカンジウム（Ｓｃ２Ｏ３）及び０．５モル％以上２．５モル％以下の酸化セリウム（ＣｅＯ２）を含む、
    請求項１に記載の固体酸化物形燃料電池用電解質シート。     The zirconia-based oxide includes 8 mol% or more and 15 mol% or less of scandium oxide (Sc 2 O 3 ) and 0.5 mol% or more and 2.5 mol% or less of cerium oxide (CeO 2 ).
    The electrolyte sheet for solid oxide fuel cells according to claim 1.
  3. 　前記希土類酸化物が、Ｙ、Ｓｍ、Ｇｄ及びＹｂからなる群から選択される少なくとも何れか１種の元素の酸化物である、
    請求項１に記載の固体酸化物形燃料電池用電解質シート。     The rare earth oxide is an oxide of at least one element selected from the group consisting of Y, Sm, Gd and Yb;
    The electrolyte sheet for solid oxide fuel cells according to claim 1.
  4. 　前記ジルコニア系酸化物が、前記希土類酸化物として、０．００３モル％以上０．２モル％以下の酸化ガドリニウム（Ｇｄ２Ｏ３）を含む、
    請求項３に記載の固体酸化物形燃料電池用電解質シート。     The zirconia-based oxide contains 0.003 mol% or more and 0.2 mol% or less of gadolinium oxide (Gd 2 O 3 ) as the rare earth oxide.
    The electrolyte sheet for solid oxide fuel cells according to claim 3.
  5. 　前記ジルコニア系酸化物が、前記希土類酸化物として、０．００３モル％以上０．２モル％以下の酸化イットリウム（Ｙ２Ｏ３）をさらに含む、
    請求項４に記載の固体酸化物形燃料電池用電解質シート。     The zirconia-based oxide further contains 0.003 mol% or more and 0.2 mol% or less of yttrium oxide (Y 2 O 3 ) as the rare earth oxide.
    The electrolyte sheet for solid oxide fuel cells according to claim 4.
  6. 　電解質成分を含み、
    　前記電解質成分が、酸化スカンジウム（Ｓｃ２Ｏ３）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物を含むジルコニア系酸化物で構成されており、
    　前記希土類酸化物は、Ｓｃを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である、
    固体酸化物形燃料電池用電解質シート。     Including electrolyte components,
    The electrolyte component is composed of a zirconia-based oxide that is stabilized with scandium oxide (Sc 2 O 3 ) and contains a rare earth oxide of 0.003 mol% or more and less than 0.5 mol%,
    The rare earth oxide is an oxide of at least one element selected from rare earth elements excluding Sc.
    Electrolyte sheet for solid oxide fuel cell.
  7. 　前記ジルコニア系酸化物は、４モル％以上１５モル％以下の酸化スカンジウム（Ｓｃ２Ｏ３）を含む、
    請求項６に記載の固体酸化物形燃料電池用電解質シート。     The zirconia-based oxide includes 4 mol% or more and 15 mol% or less of scandium oxide (Sc 2 O 3 ).
    The electrolyte sheet for solid oxide fuel cells according to claim 6.
  8. 　前記希土類酸化物が、Ｙ、Ｃｅ、Ｓｍ、Ｇｄ及びＹｂからなる群から選択される少なくとも何れか１種の元素の酸化物である、
    請求項６に記載の固体酸化物形燃料電池用電解質シート。     The rare earth oxide is an oxide of at least one element selected from the group consisting of Y, Ce, Sm, Gd and Yb;
    The electrolyte sheet for solid oxide fuel cells according to claim 6.
  9. 　燃料極と、空気極と、前記燃料極と前記空気極との間に配置された請求項１又は６に記載の固体酸化物形燃料電池用電解質シートと、を備えた電解質支持型セル。 An electrolyte supporting cell comprising: a fuel electrode; an air electrode; and the electrolyte sheet for a solid oxide fuel cell according to claim 1 or 6 disposed between the fuel electrode and the air electrode.
  10. 　燃料極と、空気極と、前記燃料極と前記空気極との間に配置された固体電解質層とを備え、
    　前記燃料極、前記空気極及び前記固体電解質層から選ばれる少なくとも何れか１つが、酸化スカンジウム（Ｓｃ２Ｏ３）及び酸化セリウム（ＣｅＯ２）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物を含むジルコニア系酸化物を電解質成分として含み、
    　前記希土類酸化物は、Ｓｃ及びＣｅを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である、
    固体酸化物形燃料電池用単セル。     A fuel electrode, an air electrode, and a solid electrolyte layer disposed between the fuel electrode and the air electrode,
    At least one selected from the fuel electrode, the air electrode, and the solid electrolyte layer is stabilized with scandium oxide (Sc 2 O 3 ) and cerium oxide (CeO 2 ), and is 0.003 mol% or more and 0 A zirconia-based oxide containing less than 5 mol% rare earth oxide as an electrolyte component;
    The rare earth oxide is an oxide of at least one element selected from rare earth elements excluding Sc and Ce.
    Single cell for solid oxide fuel cells.
  11. 　前記ジルコニア系酸化物は、８モル％以上１５モル％以下の酸化スカンジウム（Ｓｃ２Ｏ３）及び０．５モル％以上２．５モル％以下の酸化セリウム（ＣｅＯ２）を含む、
    請求項１０に記載の固体酸化物形燃料電池用単セル。     The zirconia-based oxide includes 8 mol% or more and 15 mol% or less of scandium oxide (Sc 2 O 3 ) and 0.5 mol% or more and 2.5 mol% or less of cerium oxide (CeO 2 ).
    The single cell for solid oxide fuel cells according to claim 10.
  12. 　前記希土類酸化物が、Ｙ、Ｓｍ、Ｇｄ及びＹｂからなる群から選択される少なくとも何れか１種の元素の酸化物である、
    請求項１０に記載の固体酸化物形燃料電池用単セル。     The rare earth oxide is an oxide of at least one element selected from the group consisting of Y, Sm, Gd and Yb;
    The single cell for solid oxide fuel cells according to claim 10.
  13. 　前記ジルコニア系酸化物が、前記希土類酸化物として、０．００３モル％以上０．２モル％以下の酸化ガドリニウム（Ｇｄ２Ｏ３）を含む、
    請求項１２に記載の固体酸化物形燃料電池用単セル。     The zirconia-based oxide contains 0.003 mol% or more and 0.2 mol% or less of gadolinium oxide (Gd 2 O 3 ) as the rare earth oxide.
    The single cell for solid oxide fuel cells according to claim 12.
  14. 　前記ジルコニア系酸化物が、前記希土類酸化物として、０．００３モル％以上０．２モル％以下の酸化イットリウム（Ｙ２Ｏ３）をさらに含む、
    請求項１３に記載の固体酸化物形燃料電池用単セル。     The zirconia-based oxide further contains 0.003 mol% or more and 0.2 mol% or less of yttrium oxide (Y 2 O 3 ) as the rare earth oxide.
    The single cell for solid oxide fuel cells according to claim 13.
  15. 　燃料極と、空気極と、前記燃料極と前記空気極との間に配置された固体電解質層とを備え、
    　前記燃料極、前記空気極及び前記固体電解質層から選ばれる少なくとも何れか１つが、酸化スカンジウム（Ｓｃ２Ｏ３）で安定化され、かつ、０．００３モル％以上０．５モル％未満の希土類酸化物を含むジルコニア系酸化物を電解質成分として含み、
    　前記希土類酸化物は、Ｓｃを除く希土類元素から選択される少なくとも何れか１種の元素の酸化物である、
    固体酸化物形燃料電池用単セル。     A fuel electrode, an air electrode, and a solid electrolyte layer disposed between the fuel electrode and the air electrode,
    At least one selected from the fuel electrode, the air electrode, and the solid electrolyte layer is stabilized with scandium oxide (Sc 2 O 3 ), and the rare earth is not less than 0.003 mol% and less than 0.5 mol% A zirconia oxide containing oxide is included as an electrolyte component,
    The rare earth oxide is an oxide of at least one element selected from rare earth elements excluding Sc.
    Single cell for solid oxide fuel cells.
  16. 　前記ジルコニア系酸化物は、４モル％以上１５モル％以下の酸化スカンジウム（Ｓｃ２Ｏ３）を含む、
    請求項１５に記載の固体酸化物形燃料電池用単セル。     The zirconia-based oxide includes 4 mol% or more and 15 mol% or less of scandium oxide (Sc 2 O 3 ).
    The single cell for solid oxide fuel cells according to claim 15.
  17. 　前記希土類酸化物が、Ｙ、Ｃｅ、Ｓｍ、Ｇｄ及びＹｂからなる群から選択される少なくとも何れか１種の元素の酸化物である、
    請求項１５に記載の固体酸化物形燃料電池用単セル。     The rare earth oxide is an oxide of at least one element selected from the group consisting of Y, Ce, Sm, Gd and Yb;
    The single cell for solid oxide fuel cells according to claim 15.
  18. 　前記固体電解質層に含まれる電解質成分が、前記ジルコニア系酸化物で構成されている、
    請求項１０又は１５に記載の固体酸化物形燃料電池用単セル。     The electrolyte component contained in the solid electrolyte layer is composed of the zirconia-based oxide,
    The single cell for solid oxide fuel cells according to claim 10 or 15.
  19. 　前記燃料極及び前記空気極から選ばれる少なくとも何れか１つが、前記ジルコニア系酸化物を電極組成物の一部として含んでいる、
    請求項１０又は１５に記載の固体酸化物形燃料電池用単セル。     At least one selected from the fuel electrode and the air electrode contains the zirconia-based oxide as a part of the electrode composition.
    The single cell for solid oxide fuel cells according to claim 10 or 15.
  20. 　請求項９に記載の電解質支持型セル、又は、請求項１０又は１５に記載の固体酸化物形燃料電池用単セルを備えた、固体酸化物形燃料電池。
          A solid oxide fuel cell comprising the electrolyte-supported cell according to claim 9 or the single cell for a solid oxide fuel cell according to claim 10 or 15.
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