WO2023203870A1 - Electrochemical cell - Google Patents

Electrochemical cell Download PDF

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Publication number
WO2023203870A1
WO2023203870A1 PCT/JP2023/006760 JP2023006760W WO2023203870A1 WO 2023203870 A1 WO2023203870 A1 WO 2023203870A1 JP 2023006760 W JP2023006760 W JP 2023006760W WO 2023203870 A1 WO2023203870 A1 WO 2023203870A1
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Prior art keywords
electrolyte
hydrogen electrode
concentration
electrode
mol
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PCT/JP2023/006760
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French (fr)
Japanese (ja)
Inventor
隆平 小原
陽平 岡田
真司 藤崎
誠 大森
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日本碍子株式会社
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Publication of WO2023203870A1 publication Critical patent/WO2023203870A1/en

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/02—Hydrogen or oxygen
    • C25B1/04—Hydrogen or oxygen by electrolysis of water
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • 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
    • 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
    • H01M8/1213—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the electrode/electrolyte combination or the supporting material
    • 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
    • H01M8/1253—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 zirconium oxide
    • 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

Definitions

  • the present invention relates to an electrochemical cell.
  • a fuel cell is known as an example of an electrochemical cell (see, for example, Patent Document 1).
  • a fuel cell includes a hydrogen electrode, an oxygen electrode, and an electrolyte disposed between the hydrogen electrode and the oxygen electrode.
  • the electrolyte is composed of an ionically conductive material.
  • a typical example of the ion conductive material is YSZ (yttria stabilized zirconia).
  • An object of the present invention is to provide an electrochemical cell that can reduce the resistance overvoltage of the electrolyte near the hydrogen electrode.
  • the electrochemical cell according to the present invention includes a hydrogen electrode, an oxygen electrode, and an electrolyte disposed between the hydrogen electrode and the oxygen electrode.
  • the electrolyte has a first portion that is within 3 ⁇ m from the surface on the hydrogen electrode side, and a second portion that is more than 3 ⁇ m from the surface on the hydrogen electrode side.
  • Each of the first and second portions includes yttria stabilized zirconia. The yttrium concentration in the first portion is higher than the yttrium concentration in the second portion.
  • an electrochemical cell that can reduce resistance overvoltage in the vicinity of the hydrogen electrode in the electrolyte.
  • FIG. 1 is a perspective view of a fuel cell.
  • FIG. 2 is a cross-sectional view of the fuel cell.
  • FIG. 3 is a partially enlarged view of FIG. 2.
  • FIG. 1 is a perspective view of a fuel cell 10.
  • FIG. 2 is a cross-sectional view of the fuel cell 10 taken along a gas flow path 21, which will be described later.
  • the fuel cell 10 includes a support substrate 20 and a plurality of power generation element sections 30.
  • the support substrate 20 is formed into a flat plate shape.
  • the dimension in the length direction (x-axis direction) is longer than the dimension in the width direction (y-axis direction), but the dimension in the width direction may be longer than the length direction. .
  • the support substrate 20 has a first main surface S1 and a second main surface T1.
  • the first main surface S1 and the second main surface T1 face oppositely to each other in the thickness direction (z-axis direction) of the support substrate 20.
  • the first main surface S1 and the second main surface T1 support each power generation element section 30.
  • the support substrate 20 is made of a porous material that does not have electronic conductivity.
  • the support substrate 20 is made of, for example, CSZ (calcia stabilized zirconia).
  • the support substrate 20 may be composed of NiO (nickel oxide) and YSZ (yttria stabilized zirconia), or may be composed of NiO (nickel oxide) and Y 2 O 3 (yttria).
  • the porosity of the support substrate 20 can be, for example, 20% or more and 60% or less. In this specification, porosity is the ratio of the area of the gas phase to the total area of the solid phase and gas phase in cross-sectional observation using a SEM (scanning electron microscope).
  • a plurality of gas channels 21 are formed inside the support substrate 20.
  • Each gas flow path 21 is supplied with fuel gas such as hydrogen gas.
  • each gas flow path 21 extends in the length direction (x-axis direction) within the support substrate 20.
  • Each gas flow path 21 penetrates the support substrate 20. It is preferable that each gas flow path 21 is arranged at substantially equal intervals.
  • the support substrate 20 is covered with a dense layer 22.
  • the dense layer 22 covers a region of the surface of the support substrate 20 that is not covered by each power generation element section 30 .
  • the dense layer 22 suppresses the gas diffused within the support substrate 20 from being discharged to the outside.
  • the dense layer 22 is made of, for example, CSZ (calcia-stabilized zirconia), YSZ (8YSZ) (yttria-stabilized zirconia), LSGM (lanthanum gallate), MgO (magnesium oxide) and MgAlO 4 (magnesia alumina spinel), GDC (gadolinium-doped Ceria) or LaCrO 3 (lanthanum chromite).
  • the dense layer 22 is denser than the support substrate 20.
  • the porosity of the dense layer 22 can be, for example, 0% or more and 7% or less.
  • each power generation element section 30 is supported by the first main surface S1 or the second main surface T1 of the support substrate 20.
  • the number of power generation element sections 30 arranged on the first main surface S1 and the number of power generation element sections 30 arranged on the second main surface T1 may be the same or different.
  • the sizes of the power generating element sections 30 may be the same or different.
  • the power generation element sections 30 are arranged at intervals along the length direction (x-axis direction) in which the gas flow path 21 extends.
  • the power generation element sections 30 are electrically connected in series to each other by an electrical connection section 9, which will be described later.
  • the power generation element section 30 includes a first current collecting section 1 , a hydrogen electrode 2 , an electrolyte 3 , a reaction prevention layer 4 , an oxygen electrode 5 , a second current collecting section 6 , and an interconnector 7 .
  • the first current collector 1 is arranged within the recess 23 of the support substrate 20.
  • the first current collector 1 has a first recess 11 and a second recess 12 .
  • the hydrogen electrode 2 is placed inside the first recess 11 .
  • the interconnector 7 is arranged within the second recess 12 .
  • the first current collector 1 is made of a porous material having electron conductivity.
  • the first current collector 1 can be made of, for example, NiO (nickel oxide) and Y 2 O 3 (yttria).
  • the first current collector 1 may be composed of NiO (nickel oxide) and 8YSZ (yttria stabilized zirconia), or may be composed of NiO (nickel oxide) and CSZ (calcia stabilized zirconia). Good too.
  • the porosity of the first current collector 1 can be, for example, 10% or more and 50% or less.
  • the thickness of the first current collector 1 can be, for example, 50 ⁇ m or more and 500 ⁇ m or less.
  • Hydrogen electrode 2 is arranged within first recess 11 of first current collector 1 . Fuel gas is supplied to the hydrogen electrode 2 from the gas flow path 21 via the support substrate 20 and the first current collector 1 . At the hydrogen electrode 2, an electrode reaction expressed by the following formula (1) occurs. H2 + O2- ⁇ H2O +2e -... (1)
  • the hydrogen electrode 2 is made of a porous material that has electronic conductivity and ionic conductivity.
  • the porosity of the hydrogen electrode 2 can be, for example, 10% or more and 50% or less.
  • the thickness of the hydrogen electrode 2 can be, for example, more than 10 ⁇ m and less than 100 ⁇ m. The configuration of the hydrogen electrode 2 will be described later.
  • the electrolyte 3 is arranged to cover the hydrogen electrode 2. Both ends of the electrolyte 3 in the length direction (x-axis direction) are connected to an interconnector 7 .
  • the electrolyte 3 is made of a dense material that has ionic conductivity and no electronic conductivity.
  • the porosity of the electrolyte 3 can be, for example, 0% or more and 7% or less.
  • the thickness of the electrolyte 3 can be, for example, 3 ⁇ m or more and 50 ⁇ m or less. The structure of the electrolyte 3 will be described later.
  • Reaction prevention layer 4 is arranged between electrolyte 3 and oxygen electrode 5.
  • the reaction prevention layer 4 is in contact with the electrolyte 3 and the oxygen electrode 5, respectively.
  • the reaction prevention layer 4 is arranged at a position corresponding to the hydrogen electrode 2 with the electrolyte 3 interposed therebetween.
  • the reaction prevention layer 4 is provided to prevent the constituent materials of the electrolyte 3 and the constituent materials of the oxygen electrode 5 from reacting to form a reaction layer with high electrical resistance.
  • the reaction prevention layer 4 can be made of an ion conductive material.
  • the porosity of the reaction prevention layer 4 can be, for example, 0.1% or more and 50% or less.
  • the thickness of the reaction prevention layer 4 can be, for example, 1 ⁇ m or more and 50 ⁇ m or less.
  • Oxygen electrode 5 is placed on reaction prevention layer 4 .
  • Oxygen-containing gas for example, air
  • Oxygen-containing gas for example, air
  • an electrode reaction expressed by the following equation (2) occurs. (1/2) ⁇ O 2 +2e ⁇ ⁇ O 2 ⁇ ...(2)
  • the oxygen electrode 5 is made of a porous material having electronic conductivity.
  • the porosity of the oxygen electrode 5 can be, for example, 10% or more and 50% or less.
  • the thickness of the oxygen electrode 5 can be, for example, 10 ⁇ m or more and 100 ⁇ m or less.
  • the second current collector 6 is connected to the oxygen electrode 5 and the interconnector 7.
  • the second current collector 6 is made of a porous material having electron conductivity.
  • the second current collector 6 may or may not have oxygen ion conductivity.
  • the second current collector 6 can be made of, for example, LSCF, LSC, Ag (silver), Ag-Pd (silver-palladium alloy), or the like.
  • the porosity of the second current collector 6 can be, for example, 25% or more and 50% or less.
  • the thickness of the second current collector 6 can be, for example, 50 ⁇ m or more and 500 ⁇ m or less.
  • the interconnector 7 is arranged within the second recess 12 of the first current collector 1 . Both ends of the interconnector 7 in the length direction (x-axis direction) are connected to the electrolyte 3 .
  • the interconnector 7 is made of a dense material that has electronic conductivity.
  • the interconnector 7 can be made of, for example, LaCrO 3 (lanthanum chromite), (Sr,La)TiO 3 (strontium titanate), or the like.
  • the porosity of the interconnector 7 can be, for example, 0% or more and 7% or less.
  • the thickness of the interconnector 7 can be, for example, 10 ⁇ m or more and 100 ⁇ m or less.
  • FIG. 3 is a partially enlarged view of FIG. 2.
  • the electrolyte 3 As shown in FIG. 3, the electrolyte 3 has a first portion 101 and a second portion 102.
  • the first portion 101 is a region of the electrolyte 3 on the hydrogen electrode 2 side. Specifically, the first portion 101 is a region of the electrolyte 3 within 3 ⁇ m from the hydrogen electrode side surface S3. Therefore, the thickness of the first portion 101 is 3 ⁇ m.
  • the first portion 101 is connected to the hydrogen electrode 2 .
  • the hydrogen electrode side surface S3 of the electrolyte 3 is in direct contact with the electrolyte side surface S2 of the hydrogen electrode 2.
  • the interface between the hydrogen electrode 2 and the electrolyte 3 (that is, the electrolyte side surface S2 of the hydrogen electrode 2 and the hydrogen electrode side surface S3 of the electrolyte 3) is defined as follows. First, the interface between the reaction prevention layer 4 and the oxygen electrode 5 is identified by classifying the brightness of a cross-sectional SEM image parallel to the thickness direction (z-axis direction in FIG. 3) into 256 gradations. Next, on the cross-sectional SEM image, a line having the same shape as the interface between the reaction prevention layer 4 and the oxygen electrode 5 (hereinafter referred to as the "reference line”) is translated in parallel toward the hydrogen electrode 2 side. Next, the reference line is stopped at a position where it comes into contact with nickel (Ni) contained in the hydrogen electrode 2 for the first time. The reference line at this time is the interface between the hydrogen electrode 2 and the electrolyte 3.
  • the second portion 102 is a region of the electrolyte 3 on the side opposite to the hydrogen electrode 2. Specifically, the second portion 102 is a region of the electrolyte 3 that is more than 3 ⁇ m from the hydrogen electrode side surface S3. That is, the second portion 102 is a region of the electrolyte 3 excluding the first portion 101. The second portion 102 is integrally formed with the first portion 101. The second portion 102 is connected to the anti-reaction layer 4 .
  • the first portion 101 and the second portion 102 each contain YSZ (yttria stabilized zirconia).
  • the Y (yttrium) concentration in the first portion 101 is higher than the yttrium concentration in the second portion 102.
  • the ionic conductivity of the first portion 101 of the electrolyte 3 connected to the hydrogen electrode 2 can be improved, so that the resistance overvoltage due to ion conduction can be reduced in the vicinity of the hydrogen electrode 2 of the electrolyte 3. I can do it.
  • the reaction overvoltage of the hydrogen electrode 2 can be reduced.
  • each of the first portion 101 and the second portion 102 contain YSZ as a main component.
  • "containing YSZ as a main component” means that the content of YSZ is 70 mol% or more.
  • the Y concentration in the first portion 101 can be 3.0 mol% or more and 8.0 mol% or less.
  • the Y concentration in the first portion 101 is particularly preferably 4.5 mol% or more and 7.0 mol% or less.
  • the Y concentration in the second portion 102 can be 2.0 mol% or more and 7.0 mol% or less.
  • the Y concentration in each of the first portion 101 and the second portion 102 can be adjusted by using a YSZ raw material containing a desired Y concentration.
  • the Zr concentration and Y concentration in the first portion 101 and the second portion 102 are obtained by line analysis using an atomic concentration profile, that is, elemental mapping using an EPMA (Electron Probe Micro Analyzer). Specifically, concentration distribution data of each element is obtained by performing line analysis in the z-axis direction using EPMA in a cross section along the thickness direction (z-axis direction in FIG. 3).
  • EPMA is a concept that includes EDS (Energy Dispersive x-ray Spectroscopy).
  • the hydrogen electrode 2 has a third portion 103 and a fourth portion 104.
  • the third portion 103 is a region of the hydrogen electrode 2 on the electrolyte 3 side. Specifically, the third portion 103 is a region within 10 ⁇ m from the electrolyte side surface S2 of the hydrogen electrode 2. Therefore, the thickness of the third portion 103 is 10 ⁇ m.
  • the third part 103 is connected to the electrolyte 3.
  • the electrolyte side surface S2 of the hydrogen electrode 2 is in direct contact with the hydrogen electrode side surface S3 of the electrolyte 3.
  • the third portion 103 preferably includes a solid solution of ceria-based oxide and ZrO 2 (zirconia) to which a rare earth element is added, and Ni.
  • a solid solution of ceria-based oxide and zirconia to which a rare earth element is added has both ionic conductivity derived from the ceria-based oxide and electronic conductivity derived from ZrO 2 .
  • the three-phase interface (reaction field) can be increased. Reaction resistance can be reduced.
  • a solid solution is one in which a ceria-based oxide to which a rare earth element is added and ZrO 2 are dissolved together to form a uniform solid phase.
  • ceria-based oxides doped with rare earth elements include, but are not limited to, gadolinium-doped ceria (GDC), samarium-doped ceria (SDC), and yttrium-doped ceria (YDC).
  • the Ce (cerium) concentration in the third portion 103 can be 8.0 mol% or more and 30 mol% or less.
  • the rare earth element concentration in the third portion 103 can be 0.5 mol% or more and 10 mol% or less.
  • the Zr (zirconium) concentration in the third portion 103 can be 1.0 mol% or more and 20 mol% or less.
  • the Zr concentration in the third portion 103 is particularly preferably 5.0 mol% or more and 15 mol% or less. In the third portion 103, the Zr concentration may be lower than the Ce concentration.
  • the Ni concentration in the third portion 103 can be 12 mol% or more and 50 mol% or less.
  • the fourth portion 104 is a region of the hydrogen electrode 2 on the side opposite to the electrolyte 3. Specifically, the fourth portion 104 is a region of the hydrogen electrode 2 that is more than 10 ⁇ m from the electrolyte side surface S2. That is, the fourth portion 104 is a region of the hydrogen electrode 2 excluding the third portion 103. The fourth portion 104 is integrally formed with the third portion 103. The fourth portion 104 is connected to the first current collector 1 .
  • the fourth portion 104 includes a ceria-based oxide added with a rare earth element and Ni.
  • ceria-based oxides doped with rare earth elements include, but are not limited to, GDC, SDC, and YDC.
  • the rare earth element-added ceria-based oxide contained in the fourth portion 104 is preferably the same as the rare-earth element-added ceria-based oxide contained in the fourth portion 104, but may be different.
  • the Ce concentration in the fourth portion 104 can be 10 mol% or more and 35 mol% or less.
  • the rare earth element concentration in the fourth portion 104 can be 1.0 mol% or more and 15 mol% or less.
  • the Ni concentration in the fourth portion 104 can be 12 mol% or more and 50 mol% or less.
  • the fourth portion 104 preferably includes ZrO 2 forming a solid solution with a ceria-based oxide to which a rare earth element is added.
  • the Zr concentration in the fourth portion 104 can be 0.0 mol% or more and 15 mol% or less.
  • the Zr concentration in the third portion 103 is preferably higher than the Zr concentration in the fourth portion 104 .
  • the three-phase interface in the third portion 103 can be further increased, so that the reaction resistance of the hydrogen electrode 2 can be further reduced.
  • the Ce concentration, rare earth element concentration, Zr concentration, and Ni concentration in the third portion 103 and the fourth portion 104 are obtained by line analysis using the atomic concentration profile described above.
  • a so-called horizontal striped fuel cell was described as an example of a fuel cell, but the electrochemical cell is not limited to this.
  • the present invention is applicable to an electrochemical cell in which a hydrogen electrode and an oxygen electrode are arranged on both sides of an electrolyte layer.
  • An electrochemical cell consists of an element with a pair of electrodes arranged so that an electromotive force is generated from the overall redox reaction, and an element that converts chemical energy into electrical energy. It is a generic term.
  • electrochemical cells include vertical striped fuel cells, flat plate fuel cells, cylindrical fuel cells, and hydrogen generation cells that utilize the electrolysis reaction of water.
  • An example is an electrolytic cell that performs this.
  • O 2 - (oxygen ions) are used as carriers, but OH - (hydroxide ions) or protons may be used as carriers.
  • a fuel cell of a comparative example was produced in the following manner.
  • 10 power generation element parts were formed on each main surface of the support substrate.
  • a slurry for forming a support substrate was prepared by mixing MgO powder, Y 2 O 3 powder, binder, pore-forming material, and dispersion material in a ball mill.
  • a molded body of a support substrate was created by extrusion molding and cutting this slurry for forming a support substrate.
  • a slurry for the first current collector was prepared by mixing NiO powder, Y 2 O 3 powder, binder, pore-forming material, and dispersion material in a ball mill. This slurry for the first current collector was applied by screen printing into the first recess of the molded body of the support substrate to form the molded body of the first current collector.
  • a slurry for a hydrogen electrode was prepared by mixing NiO powder, YSZ powder, binder, pore-forming material, and dispersing material in a ball mill. This hydrogen electrode slurry was applied to the second recess of the first current collector by screen printing to form a hydrogen electrode molded body.
  • a slurry for an interconnector was prepared by adding LaCrO 3 powder and a binder and mixing in a ball mill. This interconnector slurry was applied to the third recess of the first current collector by screen printing to form a molded interconnector.
  • an electrolyte slurry was prepared by mixing the YSZ powder and the binder in a ball mill. This electrolyte slurry was applied to cover the supporting substrate by screen printing to form an electrolyte molded body.
  • reaction prevention layer slurry was prepared by mixing the GDC powder and the binder in a ball mill. This reaction prevention layer slurry was applied onto the electrolyte molded body by screen printing to form a reaction prevention film molded body.
  • the laminate of each molded body was co-fired (1300°C, 5 hours) to produce a co-fired body of the support substrate, first current collector, hydrogen electrode, interconnector, electrolyte, and reaction prevention layer. .
  • a slurry for an oxygen electrode was prepared by mixing the LSCF powder, binder, pore forming material, and dispersing material in a ball mill. This oxygen electrode slurry was applied onto the reaction prevention film by screen printing to form a molded oxygen electrode.
  • a slurry for the second current collector was prepared by mixing the LSCF powder, binder, pore-forming material, and dispersing material in a ball mill. This slurry for forming a second current collector was applied from the oxygen electrode to the interconnector by a screen printing method to form a molded body of the second current collector.
  • Examples 1 to 6 Fuel cells of Examples 1 to 6 (see FIGS. 1 to 3) were produced in the same process as the comparative example except that the electrolyte had a two-layer structure.
  • the slurry for the first part was prepared by mixing the YSZ powder and the binder in a ball mill. At this time, the Y concentration in the first portion was adjusted as shown in Table 1 by changing the Y concentration contained in the YSZ powder for each example. Then, the slurry for the first portion was applied by screen printing so as to cover the support substrate, thereby forming a molded body of the first portion of the electrolyte.
  • a slurry for the second portion was prepared by mixing the YSZ powder and the binder in a ball mill.
  • the Y concentration in the second part of Examples 1 to 5 was made the same as the Y concentration in the electrolyte of the comparative example, as shown in Table 1.
  • the Y concentration in the second portion of Example 6 was lower than the Y concentration in the electrolyte of the comparative example.
  • the slurry for the second portion was applied onto the molded body of the first portion by screen printing to form a molded body of the second portion of the electrolyte.
  • Example 7 A fuel cell of Example 7 was fabricated using the same process as Example 1 except that the hydrogen electrode had a two-layer structure and ZrO 2 was added only to the third portion.
  • a slurry for the third portion was prepared by mixing NiO powder, YSZ powder, ZrO 2 powder, binder, pore-forming material, and dispersion material in a ball mill. Then, the slurry for the third portion was applied into the second recess of the first current collector by screen printing to form a molded body for the third portion of the hydrogen electrode.
  • a slurry for the fourth portion was prepared by mixing NiO powder, YSZ powder, binder, pore-forming material, and dispersing material in a ball mill. Then, the slurry for the fourth part was applied onto the molded body of the third part by a screen printing method to form a molded body of the fourth part of the hydrogen electrode.
  • Example 8 to 12 Fuel cells of Examples 8 to 12 were produced in the same process as Example 7 except that ZrO 2 was also added to the fourth portion of the hydrogen electrode.
  • a slurry for the third portion was prepared by mixing NiO powder, YSZ powder, ZrO 2 powder, binder, pore-forming material, and dispersion material in a ball mill.
  • the Zr concentration in the third portion was adjusted as shown in Table 1 by changing the Zr concentration contained in the ZrO 2 powder for each example.
  • the slurry for the third portion was applied into the second recess of the first current collector by screen printing to form a molded body for the third portion of the hydrogen electrode.
  • a slurry for the fourth portion was prepared by mixing NiO powder, YSZ powder, ZrO 2 powder, binder, pore-forming material, and dispersion material in a ball mill.
  • the amount of ZrO 2 powder added was the same as in the third part of Example 7.
  • the slurry for the fourth part was applied onto the molded body of the third part by a screen printing method to form a molded body of the fourth part of the hydrogen electrode.
  • Reaction overvoltage suppression rate (%) of each example 100 ⁇ ((reaction overvoltage of comparative example) - (reaction overvoltage of each example)) / (reaction overvoltage of comparative example)... (3)
  • the calculated reaction overvoltage suppression rate values and their evaluations are shown in Table 1.
  • Table 1 when the reaction overvoltage suppression rate is 25% or more, it is evaluated as “A”, when it is 20% or more and less than 25%, it is evaluated as “B”, and when it is 10% or more and less than 20%, it is evaluated as "B”. The case where it was less than 10% was evaluated as "C”, and the case where it was less than 10% was evaluated as "D”.
  • Heat cycle test While maintaining a reducing atmosphere by supplying a mixed gas of Ar and hydrogen (hydrogen: 4% to Ar) to the hydrogen electrode, the temperature was raised from room temperature to 750°C in 2 hours, and then cooled down to room temperature in 4 hours. This step was repeated 10 times as one cycle.
  • the initial performance can be further improved compared to Example 1. did it. This result was obtained because the three-phase interface (reaction field) could be increased in the third portion 103.
  • the existence of the ceria-based oxide containing rare earth elements and the solid solution of ZrO2 in the third part was confirmed by elemental mapping by area analysis using EDX (energy dispersive X-ray spectrometer) . This was confirmed by being observed at the same location.
  • Example 8 to 12 in which the fourth part of the hydrogen electrode includes a ceria-based oxide to which a rare earth element is added, a ZrO 2 solid solution, and Ni, the durability in the thermal cycle test is improved compared to Example 1. I was able to do it. This result was obtained because the addition of ZrO 2 strengthened the ceria-based oxide skeleton in the fourth portion. The existence of the rare earth element-doped ceria-based oxide and ZrO 2 solid solution in the second part is confirmed by the fact that Zr and CeO 2 are observed at the same position in elemental mapping by surface analysis using EDX. confirmed.
  • Examples 9 to 12 in which both the third and fourth parts of the hydrogen electrode contained ZrO 2 and the zirconium concentration in the third part was higher than the zirconium concentration in the fourth part, Examples 7 and 8 We were able to improve the initial performance compared to . This result was obtained because the three-phase interface in the third portion could be further increased.
  • Example 9 to 12 in Examples 10 and 11 in which the zirconium concentration in the third portion was 5 mol% or more and 15 mol% or less, the initial performance could be further improved.
  • Fuel cell 20 Support substrate 30 Power generation element section 1 First current collector 2 Hydrogen electrode 103 Third section 104 Fourth section 3 Electrolyte 101 First section 102 Second section 4 Reaction prevention layer 5 Oxygen electrode 6 Second current collector Part 7 Interconnector

Abstract

A fuel battery cell (10) comprises a hydrogen electrode (2), an oxygen electrode (5), and an electrolyte (3). The electrolyte (3) has: a first portion (101) within 3 μm from a hydrogen electrode-side surface (S3); and a second portion (102) which is more than 3 μm away from the hydrogen electrode-side surface (S3). The first portion (101) and the second portion (102) each contain YSZ. The Y concentration in the first portion (101) is higher than the Y concentration in the second portion (102).

Description

電気化学セルelectrochemical cell
　本発明は、電気化学セルに関するものである。 The present invention relates to an electrochemical cell.
　電気化学セルの一例として燃料電池が知られている（例えば、特許文献１参照）。燃料電池は、水素極と、酸素極と、水素極及び酸素極の間に配置される電解質とを備える。電解質は、イオン伝導性材料によって構成される。イオン伝導性材料としては、ＹＳＺ（イットリア安定化ジルコニア）が代表的である。 A fuel cell is known as an example of an electrochemical cell (see, for example, Patent Document 1). A fuel cell includes a hydrogen electrode, an oxygen electrode, and an electrolyte disposed between the hydrogen electrode and the oxygen electrode. The electrolyte is composed of an ionically conductive material. A typical example of the ion conductive material is YSZ (yttria stabilized zirconia).
特開２０１３－２４１６４４号公報Japanese Patent Application Publication No. 2013-241644
　燃料電池では、電解質のうち水素極近傍における抵抗過電圧を低減させることによって電池特性を向上させることが期待されている。また、電解質のうち水素極近傍における抵抗過電圧を低減させることは、燃料電池に限らず電解セルなどの電気化学セル一般に有用である。 In fuel cells, it is expected that cell characteristics will be improved by reducing the resistance overvoltage near the hydrogen electrode in the electrolyte. Further, reducing the resistance overvoltage in the vicinity of the hydrogen electrode in the electrolyte is useful not only for fuel cells but also for general electrochemical cells such as electrolytic cells.
　本発明の課題は、水素極近傍の電解質の抵抗過電圧を低減可能な電気化学セルを提供することである。 An object of the present invention is to provide an electrochemical cell that can reduce the resistance overvoltage of the electrolyte near the hydrogen electrode.
　本発明に係る電気化学セルは、水素極と、酸素極と、水素極及び酸素極の間に配置される電解質とを備える。電解質は、水素極側表面から３μｍ以内の第１部分と、水素極側表面から３μｍ超の第２部分とを有する。第１部分及び第２部分それぞれは、イットリア安定化ジルコニアを含む。第１部分におけるイットリウム濃度は、第２部分におけるイットリウム濃度より高い。 The electrochemical cell according to the present invention includes a hydrogen electrode, an oxygen electrode, and an electrolyte disposed between the hydrogen electrode and the oxygen electrode. The electrolyte has a first portion that is within 3 μm from the surface on the hydrogen electrode side, and a second portion that is more than 3 μm from the surface on the hydrogen electrode side. Each of the first and second portions includes yttria stabilized zirconia. The yttrium concentration in the first portion is higher than the yttrium concentration in the second portion.
　本発明によれば、電解質のうち水素極近傍における抵抗過電圧を低減可能な電気化学セルを提供することができる。 According to the present invention, it is possible to provide an electrochemical cell that can reduce resistance overvoltage in the vicinity of the hydrogen electrode in the electrolyte.
図１は、燃料電池セルの斜視図である。FIG. 1 is a perspective view of a fuel cell. 図２は、燃料電池セルの断面図である。FIG. 2 is a cross-sectional view of the fuel cell. 図３は、図２の部分拡大図である。FIG. 3 is a partially enlarged view of FIG. 2.
　（燃料電池セル１０）
　電気化学セルの一例として燃料電池セル１０について説明する。図１は、燃料電池セル１０の斜視図である。図２は、後述するガス流路２１に沿って切断した燃料電池セル１０の断面図である。 (Fuel cell cell 10)
A fuel cell 10 will be described as an example of an electrochemical cell. FIG. 1 is a perspective view of a fuel cell 10. FIG. 2 is a cross-sectional view of the fuel cell 10 taken along a gas flow path 21, which will be described later.
　図１及び図２に示すように、燃料電池セル１０は、支持基板２０及び複数の発電素子部３０を備える。 As shown in FIGS. 1 and 2, the fuel cell 10 includes a support substrate 20 and a plurality of power generation element sections 30.
　［支持基板２０］
　図１に示すように、支持基板２０は、扁平な板状に形成される。本実施形態に係る支持基板２０では、長さ方向（ｘ軸方向）の寸法が、幅方向（ｙ軸方向）の寸法より長いが、長さ方向より幅方向の寸法の方が長くてもよい。 [Support board 20]
As shown in FIG. 1, the support substrate 20 is formed into a flat plate shape. In the support substrate 20 according to this embodiment, the dimension in the length direction (x-axis direction) is longer than the dimension in the width direction (y-axis direction), but the dimension in the width direction may be longer than the length direction. .
　図２に示すように、支持基板２０は、第１主面Ｓ１と、第２主面Ｔ１とを有する。第１主面Ｓ１と第２主面Ｔ１とは、支持基板２０の厚さ方向（ｚ軸方向）において互いに反対を向いている。第１主面Ｓ１及び第２主面Ｔ１は、各発電素子部３０を支持する。 As shown in FIG. 2, the support substrate 20 has a first main surface S1 and a second main surface T1. The first main surface S1 and the second main surface T1 face oppositely to each other in the thickness direction (z-axis direction) of the support substrate 20. The first main surface S1 and the second main surface T1 support each power generation element section 30.
　支持基板２０は、電子伝導性を有さない多孔質材料によって構成される。支持基板２０は、例えば、ＣＳＺ（カルシア安定化ジルコニア）によって構成される。或いは、支持基板２０は、ＮｉＯ（酸化ニッケル）とＹＳＺ（イットリア安定化ジルコニア）とによって構成されてもよいし、ＮｉＯ（酸化ニッケル）とＹ２Ｏ３（イットリア）とによって構成されてもよいし、ＭｇＯ（酸化マグネシウム）とＭｇＡｌ２Ｏ４（マグネシアアルミナスピネル）とによって構成されてもよい。支持基板２０の気孔率は、例えば、２０％以上６０％以下とすることができる。本明細書において、気孔率とは、ＳＥＭ（走査電子顕微鏡）を用いた断面観察における固相と気相の総面積に対する気相の面積の割合である。 The support substrate 20 is made of a porous material that does not have electronic conductivity. The support substrate 20 is made of, for example, CSZ (calcia stabilized zirconia). Alternatively, the support substrate 20 may be composed of NiO (nickel oxide) and YSZ (yttria stabilized zirconia), or may be composed of NiO (nickel oxide) and Y 2 O 3 (yttria). , MgO (magnesium oxide) and MgAl 2 O 4 (magnesia alumina spinel). The porosity of the support substrate 20 can be, for example, 20% or more and 60% or less. In this specification, porosity is the ratio of the area of the gas phase to the total area of the solid phase and gas phase in cross-sectional observation using a SEM (scanning electron microscope).
　支持基板２０の内部には、複数のガス流路２１が形成されている。各ガス流路２１には、水素ガスなどの燃料ガスが供給される。本実施形態において、各ガス流路２１は、支持基板２０内を長さ方向（ｘ軸方向）に延びる。各ガス流路２１は、支持基板２０を貫通する。各ガス流路２１は、実質的に等間隔に配置されることが好ましい。 A plurality of gas channels 21 are formed inside the support substrate 20. Each gas flow path 21 is supplied with fuel gas such as hydrogen gas. In this embodiment, each gas flow path 21 extends in the length direction (x-axis direction) within the support substrate 20. Each gas flow path 21 penetrates the support substrate 20. It is preferable that each gas flow path 21 is arranged at substantially equal intervals.
　図１に示すように、支持基板２０は、緻密層２２によって覆われている。緻密層２２は、支持基板２０の表面のうち各発電素子部３０によって覆われていない領域を覆う。緻密層２２は、支持基板２０内に拡散されたガスが外部に排出されることを抑制する。緻密層２２は、例えば、ＣＳＺ（カルシア安定化ジルコニア）、ＹＳＺ（８ＹＳＺ）（イットリア安定化ジルコニア）、ＬＳＧＭ（ランタンガレート）、ＭｇＯ（酸化マグネシウム）とＭｇＡｌＯ４（マグネシアアルミナスピネル）、ＧＤＣ（ガドリニウムドープセリア）又はＬａＣｒＯ３（ランタンクロマイト）などによって構成される。緻密層２２は、支持基板２０よりも緻密である。緻密層２２の気孔率は、例えば、０％以上７％以下とすることができる。 As shown in FIG. 1, the support substrate 20 is covered with a dense layer 22. The dense layer 22 covers a region of the surface of the support substrate 20 that is not covered by each power generation element section 30 . The dense layer 22 suppresses the gas diffused within the support substrate 20 from being discharged to the outside. The dense layer 22 is made of, for example, CSZ (calcia-stabilized zirconia), YSZ (8YSZ) (yttria-stabilized zirconia), LSGM (lanthanum gallate), MgO (magnesium oxide) and MgAlO 4 (magnesia alumina spinel), GDC (gadolinium-doped Ceria) or LaCrO 3 (lanthanum chromite). The dense layer 22 is denser than the support substrate 20. The porosity of the dense layer 22 can be, for example, 0% or more and 7% or less.
　［発電素子部３０］
　図１に示すように、各発電素子部３０は、支持基板２０の第１主面Ｓ１又は第２主面Ｔ１に支持されている。第１主面Ｓ１に配置される発電素子部３０の数と第２主面Ｔ１に配置される発電素子部３０の数とは、互いに同じであってもよいし異なっていてもよい。また、各発電素子部３０の大きさは、互いに同じであってもよいし異なっていてもよい。 [Power generation element section 30]
As shown in FIG. 1, each power generation element section 30 is supported by the first main surface S1 or the second main surface T1 of the support substrate 20. The number of power generation element sections 30 arranged on the first main surface S1 and the number of power generation element sections 30 arranged on the second main surface T1 may be the same or different. Furthermore, the sizes of the power generating element sections 30 may be the same or different.
　各発電素子部３０は、ガス流路２１が延びる長さ方向（ｘ軸方向）に沿って間隔をあけて配置される。各発電素子部３０は、後述する電気的接続部９によって、互いに電気的に直列に接続される。 The power generation element sections 30 are arranged at intervals along the length direction (x-axis direction) in which the gas flow path 21 extends. The power generation element sections 30 are electrically connected in series to each other by an electrical connection section 9, which will be described later.
　発電素子部３０は、第１集電部１、水素極２、電解質３、反応防止層４、酸素極５、第２集電部６、及びインターコネクタ７を備える。 The power generation element section 30 includes a first current collecting section 1 , a hydrogen electrode 2 , an electrolyte 3 , a reaction prevention layer 4 , an oxygen electrode 5 , a second current collecting section 6 , and an interconnector 7 .
　第１集電部１は、支持基板２０の凹部２３内に配置される。第１集電部１は、第１凹部１１及び第２凹部１２を有する。第１凹部１１内には、水素極２が配置される。第２凹部１２内には、インターコネクタ７が配置される。 The first current collector 1 is arranged within the recess 23 of the support substrate 20. The first current collector 1 has a first recess 11 and a second recess 12 . The hydrogen electrode 2 is placed inside the first recess 11 . The interconnector 7 is arranged within the second recess 12 .
　第１集電部１は、電子伝導性を有する多孔質材料によって構成される。第１集電部１は、例えば、ＮｉＯ（酸化ニッケル）とＹ２Ｏ３（イットリア）とによって構成することができる。或いは、第１集電部１は、ＮｉＯ（酸化ニッケル）と８ＹＳＺ（イットリア安定化ジルコニア）とによって構成されてもよいし、ＮｉＯ（酸化ニッケル）とＣＳＺ（カルシア安定化ジルコニア）とによって構成されてもよい。 The first current collector 1 is made of a porous material having electron conductivity. The first current collector 1 can be made of, for example, NiO (nickel oxide) and Y 2 O 3 (yttria). Alternatively, the first current collector 1 may be composed of NiO (nickel oxide) and 8YSZ (yttria stabilized zirconia), or may be composed of NiO (nickel oxide) and CSZ (calcia stabilized zirconia). Good too.
　第１集電部１の気孔率は、例えば、１０％以上５０％以下とすることができる。第１集電部１の厚さは、例えば、５０μｍ以上５００μｍ以下とすることができる。 The porosity of the first current collector 1 can be, for example, 10% or more and 50% or less. The thickness of the first current collector 1 can be, for example, 50 μm or more and 500 μm or less.
　水素極２は、第１集電部１の第１凹部１１内に配置される。水素極２には、支持基板２０及び第１集電部１を介して、ガス流路２１から燃料ガスが供給される。水素極２では、次の式（１）で表される電極反応が起こる。
　Ｈ２＋Ｏ２－→Ｈ２Ｏ＋２ｅ－　　　　　…（１） Hydrogen electrode 2 is arranged within first recess 11 of first current collector 1 . Fuel gas is supplied to the hydrogen electrode 2 from the gas flow path 21 via the support substrate 20 and the first current collector 1 . At the hydrogen electrode 2, an electrode reaction expressed by the following formula (1) occurs.
H2 + O2- → H2O +2e -... (1)
　水素極２は、電子伝導性及びイオン伝導性を有する多孔質材料によって構成される。水素極２の気孔率は、例えば、１０％以上５０％以下とすることができる。水素極２の厚さは、例えば、１０μｍ超１００μｍ以下とすることができる。水素極２の構成については後述する。 The hydrogen electrode 2 is made of a porous material that has electronic conductivity and ionic conductivity. The porosity of the hydrogen electrode 2 can be, for example, 10% or more and 50% or less. The thickness of the hydrogen electrode 2 can be, for example, more than 10 μm and less than 100 μm. The configuration of the hydrogen electrode 2 will be described later.
　電解質３は、水素極２を覆うように配置される。長さ方向（ｘ軸方向）における電解質３の両端部それぞれは、インターコネクタ７に接続される。電解質３は、イオン伝導性を有し且つ電子伝導性を有さない緻密質材料によって構成される。電解質３の気孔率は、例えば、０％以上７％以下とすることができる。電解質３の厚さは、例えば、３μｍ以上５０μｍ以下とすることができる。電解質３の構成については後述する。 The electrolyte 3 is arranged to cover the hydrogen electrode 2. Both ends of the electrolyte 3 in the length direction (x-axis direction) are connected to an interconnector 7 . The electrolyte 3 is made of a dense material that has ionic conductivity and no electronic conductivity. The porosity of the electrolyte 3 can be, for example, 0% or more and 7% or less. The thickness of the electrolyte 3 can be, for example, 3 μm or more and 50 μm or less. The structure of the electrolyte 3 will be described later.
　反応防止層４は、電解質３及び酸素極５の間に配置される。反応防止層４は、電解質３及び酸素極５それぞれと接触する。反応防止層４は、電解質３を介して水素極２と対応する位置に配置される。反応防止層４は、電解質３の構成材料と酸素極５の構成材料とが反応して電気抵抗の大きい反応層が形成されることを抑制するために設けられている。反応防止層４は、イオン伝導性材料によって構成することができる。反応防止層４は、例えば、ＧＤＣ＝（Ｃｅ，Ｇｄ）Ｏ２（ガドリニウムドープセリア）によって構成することができる。反応防止層４の気孔率は、例えば、０．1％以上５０％以下とすることができる。反応防止層４の厚さは、例えば、１μｍ以上５０μｍ以下とすることができる。 Reaction prevention layer 4 is arranged between electrolyte 3 and oxygen electrode 5. The reaction prevention layer 4 is in contact with the electrolyte 3 and the oxygen electrode 5, respectively. The reaction prevention layer 4 is arranged at a position corresponding to the hydrogen electrode 2 with the electrolyte 3 interposed therebetween. The reaction prevention layer 4 is provided to prevent the constituent materials of the electrolyte 3 and the constituent materials of the oxygen electrode 5 from reacting to form a reaction layer with high electrical resistance. The reaction prevention layer 4 can be made of an ion conductive material. The reaction prevention layer 4 can be made of, for example, GDC=(Ce,Gd)O 2 (gadolinium-doped ceria). The porosity of the reaction prevention layer 4 can be, for example, 0.1% or more and 50% or less. The thickness of the reaction prevention layer 4 can be, for example, 1 μm or more and 50 μm or less.
　酸素極５は、反応防止層４上に配置される。酸素極５には、第２集電部６を介して、酸素を含むガス（例えば、空気）が供給される。酸素極５では、次の式（２）で表される電極反応が起こる。
　（１／２）・Ｏ２＋２ｅ－→Ｏ２－　　　…（２） Oxygen electrode 5 is placed on reaction prevention layer 4 . Oxygen-containing gas (for example, air) is supplied to the oxygen electrode 5 via the second current collector 6 . At the oxygen electrode 5, an electrode reaction expressed by the following equation (2) occurs.
(1/2)・O 2 +2e − →O 2 − …(2)
　酸素極５は、電子伝導性を有する多孔質材料によって構成される。酸素極５は、例えば、ＬＳＣＦ＝（Ｌａ，Ｓｒ）（Ｃｏ，Ｆｅ）Ｏ３（ランタンストロンチウムコバルトフェライト）、ＬＳＦ＝（Ｌａ，Ｓｒ）ＦｅＯ３（ランタンストロンチウムフェライト）、ＬＮＦ＝Ｌａ（Ｎｉ，Ｆｅ）Ｏ３（ランタンニッケルフェライト）、ＬＳＣ＝（Ｌａ，Ｓｒ）ＣｏＯ３（ランタンストロンチウムコバルタイト）等によって構成することができる。酸素極５の気孔率は、例えば、１０％以上５０％以下とすることができる。酸素極５の厚さは、例えば、１０μｍ以上１００μｍ以下とすることができる。 The oxygen electrode 5 is made of a porous material having electronic conductivity. The oxygen electrode 5 is made of, for example, LSCF=(La,Sr)(Co,Fe)O 3 (lanthanum strontium cobalt ferrite), LSF=(La,Sr)FeO 3 (lanthanum strontium ferrite), LNF=La(Ni,Fe ) O 3 (lanthanum nickel ferrite), LSC=(La,Sr)CoO 3 (lanthanum strontium cobaltite), or the like. The porosity of the oxygen electrode 5 can be, for example, 10% or more and 50% or less. The thickness of the oxygen electrode 5 can be, for example, 10 μm or more and 100 μm or less.
　第２集電部６は、酸素極５及びインターコネクタ７に接続される。第２集電部６は、電子伝導性を有する多孔質材料によって構成される。第２集電部６は、酸素イオン伝導性を有していてもよいし、有していなくてもよい。第２集電部６は、例えば、ＬＳＣＦ、ＬＳＣ、Ａｇ（銀）、Ａｇ－Ｐｄ（銀パラジウム合金）等によって構成することができる。第２集電部６の気孔率は、例えば、２５％以上５０％以下とすることができる。第２集電部６の厚さは、例えば、５０μｍ以上５００μｍ以下とすることができる。 The second current collector 6 is connected to the oxygen electrode 5 and the interconnector 7. The second current collector 6 is made of a porous material having electron conductivity. The second current collector 6 may or may not have oxygen ion conductivity. The second current collector 6 can be made of, for example, LSCF, LSC, Ag (silver), Ag-Pd (silver-palladium alloy), or the like. The porosity of the second current collector 6 can be, for example, 25% or more and 50% or less. The thickness of the second current collector 6 can be, for example, 50 μm or more and 500 μm or less.
　インターコネクタ７は、第１集電部１の第２凹部１２内に配置される。長さ方向（ｘ軸方向）におけるインターコネクタ７の両端部それぞれは、電解質３に接続される。インターコネクタ７は、電子伝導性を有する緻密質材料によって構成される。インターコネクタ７は、例えば、ＬａＣｒＯ３（ランタンクロマイト）、（Ｓｒ，Ｌａ）ＴｉＯ３（ストロンチウムチタネート）等によって構成することができる。インターコネクタ７の気孔率は、例えば、０％以上７％以下とすることができる。インターコネクタ７の厚さは、例えば、１０μｍ以上１００μｍ以下とすることができる。 The interconnector 7 is arranged within the second recess 12 of the first current collector 1 . Both ends of the interconnector 7 in the length direction (x-axis direction) are connected to the electrolyte 3 . The interconnector 7 is made of a dense material that has electronic conductivity. The interconnector 7 can be made of, for example, LaCrO 3 (lanthanum chromite), (Sr,La)TiO 3 (strontium titanate), or the like. The porosity of the interconnector 7 can be, for example, 0% or more and 7% or less. The thickness of the interconnector 7 can be, for example, 10 μm or more and 100 μm or less.
　（電解質３及び水素極２の構成）
　次に、電解質３及び水素極２の構成について説明する。図３は、図２の部分拡大図である。 (Configuration of electrolyte 3 and hydrogen electrode 2)
Next, the configurations of the electrolyte 3 and the hydrogen electrode 2 will be explained. FIG. 3 is a partially enlarged view of FIG. 2.
　［電解質３］
　図３に示すように、電解質３は、第１部分１０１と、第２部分１０２とを有する。 [Electrolyte 3]
As shown in FIG. 3, the electrolyte 3 has a first portion 101 and a second portion 102.
　第１部分１０１は、電解質３のうち水素極２側の領域である。具体的には、第１部分１０１は、電解質３のうち水素極側表面Ｓ３から３μｍ以内の領域である。従って、第１部分１０１の厚さは、３μｍである。第１部分１０１は、水素極２に接続される。電解質３の水素極側表面Ｓ３は、水素極２の電解質側表面Ｓ２と直接的に接触する。 The first portion 101 is a region of the electrolyte 3 on the hydrogen electrode 2 side. Specifically, the first portion 101 is a region of the electrolyte 3 within 3 μm from the hydrogen electrode side surface S3. Therefore, the thickness of the first portion 101 is 3 μm. The first portion 101 is connected to the hydrogen electrode 2 . The hydrogen electrode side surface S3 of the electrolyte 3 is in direct contact with the electrolyte side surface S2 of the hydrogen electrode 2.
　水素極２と電解質３との界面（すなわち、水素極２の電解質側表面Ｓ２及び電解質３の水素極側表面Ｓ３）は、次のように規定される。まず、厚み方向（図３のｚ軸方向）に平行な断面ＳＥＭ画像の輝度を２５６階調に分類することによって、反応防止層４と酸素極５との界面を特定する。次に、断面ＳＥＭ画像上において、反応防止層４と酸素極５との界面と同じ形状の線（以下、「基準線」という。）を水素極２側に向かって平行移動させる。次に、水素極２に含まれるニッケル（Ｎｉ）と初めて接する位置で基準線を停止させる。このときの基準線が、水素極２と電解質３との界面である。 The interface between the hydrogen electrode 2 and the electrolyte 3 (that is, the electrolyte side surface S2 of the hydrogen electrode 2 and the hydrogen electrode side surface S3 of the electrolyte 3) is defined as follows. First, the interface between the reaction prevention layer 4 and the oxygen electrode 5 is identified by classifying the brightness of a cross-sectional SEM image parallel to the thickness direction (z-axis direction in FIG. 3) into 256 gradations. Next, on the cross-sectional SEM image, a line having the same shape as the interface between the reaction prevention layer 4 and the oxygen electrode 5 (hereinafter referred to as the "reference line") is translated in parallel toward the hydrogen electrode 2 side. Next, the reference line is stopped at a position where it comes into contact with nickel (Ni) contained in the hydrogen electrode 2 for the first time. The reference line at this time is the interface between the hydrogen electrode 2 and the electrolyte 3.
　第２部分１０２は、電解質３のうち水素極２と反対側の領域である。具体的には、第２部分１０２は、電解質３のうち水素極側表面Ｓ３から３μｍ超の領域である。すなわち、第２部分１０２は、電解質３のうち第１部分１０１を除いた領域である。第２部分１０２は、第１部分１０１と一体的に形成される。第２部分１０２は、反応防止層４に接続される。 The second portion 102 is a region of the electrolyte 3 on the side opposite to the hydrogen electrode 2. Specifically, the second portion 102 is a region of the electrolyte 3 that is more than 3 μm from the hydrogen electrode side surface S3. That is, the second portion 102 is a region of the electrolyte 3 excluding the first portion 101. The second portion 102 is integrally formed with the first portion 101. The second portion 102 is connected to the anti-reaction layer 4 .
　第１部分１０１及び第２部分１０２それぞれは、ＹＳＺ（イットリア安定化ジルコニア）を含む。第１部分１０１におけるＹ（イットリウム）濃度は、第２部分１０２におけるイットリウム濃度より高い。これによって、電解質３のうち水素極２に接続される第１部分１０１のイオン伝導性を向上させることができるため、電解質３のうち水素極２近傍において、イオン伝導に伴う抵抗過電圧を低減させることができる。また、水素極２のうち電解質３近傍における三相界面のイオン伝導性が向上することで、水素極２の反応過電圧を低減させることができる。 The first portion 101 and the second portion 102 each contain YSZ (yttria stabilized zirconia). The Y (yttrium) concentration in the first portion 101 is higher than the yttrium concentration in the second portion 102. As a result, the ionic conductivity of the first portion 101 of the electrolyte 3 connected to the hydrogen electrode 2 can be improved, so that the resistance overvoltage due to ion conduction can be reduced in the vicinity of the hydrogen electrode 2 of the electrolyte 3. I can do it. Furthermore, by improving the ionic conductivity of the three-phase interface in the vicinity of the electrolyte 3 in the hydrogen electrode 2, the reaction overvoltage of the hydrogen electrode 2 can be reduced.
　第１部分１０１及び第２部分１０２それぞれは、ＹＳＺを主成分として含んでいることが好ましい。本明細書において、主成分として含むとはＹＳＺの含有率が７０ｍｏｌ％以上であることを意味する。 It is preferable that each of the first portion 101 and the second portion 102 contain YSZ as a main component. In this specification, "containing YSZ as a main component" means that the content of YSZ is 70 mol% or more.
　第１部分１０１におけるＹ濃度は、３．０ｍｏｌ％以上８．０ｍｏｌ％以下とすることができる。第１部分１０１におけるＹ濃度は、４．５ｍｏｌ％以上７．０ｍｏｌ％以下が特に好ましい。第２部分１０２におけるＹ濃度は、２．０ｍｏｌ％以上７．０ｍｏｌ％以下とすることができる。第１部分１０１及び第２部分１０２それぞれにおけるＹ濃度は、所望のＹ濃度を含むＹＳＺ原料を使用することによって調整できる。 The Y concentration in the first portion 101 can be 3.0 mol% or more and 8.0 mol% or less. The Y concentration in the first portion 101 is particularly preferably 4.5 mol% or more and 7.0 mol% or less. The Y concentration in the second portion 102 can be 2.0 mol% or more and 7.0 mol% or less. The Y concentration in each of the first portion 101 and the second portion 102 can be adjusted by using a YSZ raw material containing a desired Y concentration.
　第１部分１０１及び第２部分１０２におけるＺｒ濃度及びＹ濃度は、原子濃度プロファイルによるライン分析、すなわちＥＰＭＡ（Ｅｌｅｃｔｒｏｎ　Ｐｒｏｂｅ　Ｍｉｃｒｏ　Ａｎａｌｙｚｅｒ）を用いた元素マッピングによって得られる。具体的には、厚み方向（図３のｚ軸方向）に沿った断面において、ＥＰＭＡを用いてｚ軸方向にライン分析を行うことにより、各元素の濃度分布データが取得される。なお、ＥＰＭＡは、ＥＤＳ（Ｅｎｅｒｇｙ　Ｄｉｓｐｅｒｓｉｖｅ　ｘ－ｒａｙ　Ｓｐｅｃｔｒｏｓｃｏｐｙ）を含む概念である。 The Zr concentration and Y concentration in the first portion 101 and the second portion 102 are obtained by line analysis using an atomic concentration profile, that is, elemental mapping using an EPMA (Electron Probe Micro Analyzer). Specifically, concentration distribution data of each element is obtained by performing line analysis in the z-axis direction using EPMA in a cross section along the thickness direction (z-axis direction in FIG. 3). Note that EPMA is a concept that includes EDS (Energy Dispersive x-ray Spectroscopy).
　［水素極２］
　図３に示すように、水素極２は、第３部分１０３と、第４部分１０４とを有する。 [Hydrogen electrode 2]
As shown in FIG. 3, the hydrogen electrode 2 has a third portion 103 and a fourth portion 104.
　第３部分１０３は、水素極２のうち電解質３側の領域である。具体的には、第３部分１０３は、水素極２のうち電解質側表面Ｓ２から１０μｍ以内の領域である。従って、第３部分１０３の厚さは、１０μｍである。第３部分１０３は、電解質３に接続される。水素極２の電解質側表面Ｓ２は、電解質３の水素極側表面Ｓ３と直接的に接触する。 The third portion 103 is a region of the hydrogen electrode 2 on the electrolyte 3 side. Specifically, the third portion 103 is a region within 10 μm from the electrolyte side surface S2 of the hydrogen electrode 2. Therefore, the thickness of the third portion 103 is 10 μm. The third part 103 is connected to the electrolyte 3. The electrolyte side surface S2 of the hydrogen electrode 2 is in direct contact with the hydrogen electrode side surface S3 of the electrolyte 3.
　第３部分１０３は、希土類元素が添加されたセリア系酸化物及びＺｒＯ２（ジルコニア）の固溶体と、Ｎｉとを含むことが好ましい。希土類元素が添加されたセリア系酸化物及びジルコニアの固溶体は、セリア系酸化物由来のイオン伝導性と、ＺｒＯ２由来の電子伝導性との両方を有する。このように、水素極２のうち電極反応が活発な第３部分１０３にＺｒＯ２を含有する固溶体を含ませることによって、三相界面（反応場）を増大させることができるため、水素極２の反応抵抗を低減させることができる。 The third portion 103 preferably includes a solid solution of ceria-based oxide and ZrO 2 (zirconia) to which a rare earth element is added, and Ni. A solid solution of ceria-based oxide and zirconia to which a rare earth element is added has both ionic conductivity derived from the ceria-based oxide and electronic conductivity derived from ZrO 2 . In this way, by including a solid solution containing ZrO 2 in the third portion 103 of the hydrogen electrode 2 where the electrode reaction is active, the three-phase interface (reaction field) can be increased. Reaction resistance can be reduced.
　固溶体とは、希土類元素が添加されたセリア系酸化物とＺｒＯ２とが互いに溶け合って、全体が均一の固相となっているものをいう。希土類元素が添加されたセリア系酸化物としては、例えば、ガドリニウムドープセリア（ＧＤＣ）、サマリウムドープセリア（ＳＤＣ）、イットリウムドープセリア（ＹＤＣ）などが挙げられるが、これらには限られない。 A solid solution is one in which a ceria-based oxide to which a rare earth element is added and ZrO 2 are dissolved together to form a uniform solid phase. Examples of ceria-based oxides doped with rare earth elements include, but are not limited to, gadolinium-doped ceria (GDC), samarium-doped ceria (SDC), and yttrium-doped ceria (YDC).
　第３部分１０３におけるＣｅ（セリウム）濃度は、８．０ｍｏｌ％以上３０ｍｏｌ％以下とすることができる。第３部分１０３における希土類元素濃度は、０．５ｍｏｌ％以上１０ｍｏｌ％以下とすることができる。第３部分１０３におけるＺｒ（ジルコニウム）濃度は、１．０ｍｏｌ％以上２０ｍｏｌ％以下とすることができる。第３部分１０３におけるＺｒ濃度は、５．０ｍｏｌ％以上１５ｍｏｌ％以下が特に好ましい。第３部分１０３において、Ｚｒ濃度はＣｅ濃度より低くてよい。第３部分１０３におけるＮｉ濃度は、１２ｍｏｌ％以上５０ｍｏｌ％以下とすることができる。 The Ce (cerium) concentration in the third portion 103 can be 8.0 mol% or more and 30 mol% or less. The rare earth element concentration in the third portion 103 can be 0.5 mol% or more and 10 mol% or less. The Zr (zirconium) concentration in the third portion 103 can be 1.0 mol% or more and 20 mol% or less. The Zr concentration in the third portion 103 is particularly preferably 5.0 mol% or more and 15 mol% or less. In the third portion 103, the Zr concentration may be lower than the Ce concentration. The Ni concentration in the third portion 103 can be 12 mol% or more and 50 mol% or less.
　第４部分１０４は、水素極２のうち電解質３と反対側の領域である。具体的には、第４部分１０４は、水素極２のうち電解質側表面Ｓ２から１０μｍ超の領域である。すなわち、第４部分１０４は、水素極２のうち第３部分１０３を除いた領域である。第４部分１０４は、第３部分１０３と一体的に形成される。第４部分１０４は、第１集電部１に接続される。 The fourth portion 104 is a region of the hydrogen electrode 2 on the side opposite to the electrolyte 3. Specifically, the fourth portion 104 is a region of the hydrogen electrode 2 that is more than 10 μm from the electrolyte side surface S2. That is, the fourth portion 104 is a region of the hydrogen electrode 2 excluding the third portion 103. The fourth portion 104 is integrally formed with the third portion 103. The fourth portion 104 is connected to the first current collector 1 .
　第４部分１０４は、希土類元素が添加されたセリア系酸化物とＮｉとを含む。希土類元素が添加されたセリア系酸化物としては、例えば、ＧＤＣ、ＳＤＣ、ＹＤＣなどが挙げられるが、これらには限られない。第４部分１０４が含む希土類元素が添加されたセリア系酸化物は、第４部分１０４が含む希土類元素が添加されたセリア系酸化物と同じであることが好ましいが異なっていてもよい。 The fourth portion 104 includes a ceria-based oxide added with a rare earth element and Ni. Examples of ceria-based oxides doped with rare earth elements include, but are not limited to, GDC, SDC, and YDC. The rare earth element-added ceria-based oxide contained in the fourth portion 104 is preferably the same as the rare-earth element-added ceria-based oxide contained in the fourth portion 104, but may be different.
　第４部分１０４におけるＣｅ濃度は、１０ｍｏｌ％以上３５ｍｏｌ％以下とすることができる。第４部分１０４における希土類元素濃度は、１．０ｍｏｌ％以上１５ｍｏｌ％以下とすることができる。第４部分１０４におけるＮｉ濃度は、１２ｍｏｌ％以上５０ｍｏｌ％以下とすることができる。 The Ce concentration in the fourth portion 104 can be 10 mol% or more and 35 mol% or less. The rare earth element concentration in the fourth portion 104 can be 1.0 mol% or more and 15 mol% or less. The Ni concentration in the fourth portion 104 can be 12 mol% or more and 50 mol% or less.
　第４部分１０４は、希土類元素が添加されたセリア系酸化物との固溶体を構成するＺｒＯ２を含むことが好ましい。これによって、水素と水蒸気が共存する雰囲気において不安定になりやすいセリア系酸化物の骨格を強化できるため、水素極２の耐久性を向上させることができる。第４部分１０４におけるＺｒ濃度は、０．０ｍｏｌ％以上１５ｍｏｌ％以下とすることができる。 The fourth portion 104 preferably includes ZrO 2 forming a solid solution with a ceria-based oxide to which a rare earth element is added. As a result, the skeleton of the ceria-based oxide, which tends to become unstable in an atmosphere where hydrogen and water vapor coexist, can be strengthened, so that the durability of the hydrogen electrode 2 can be improved. The Zr concentration in the fourth portion 104 can be 0.0 mol% or more and 15 mol% or less.
　第４部分１０４がＺｒＯ２を含有している場合、第３部分１０３におけるＺｒ濃度は、第４部分１０４におけるＺｒ濃度より高いことが好ましい。これによって、第３部分１０３における三相界面を更に増大させることができるため、水素極２の反応抵抗を更に低減させることができる。 When the fourth portion 104 contains ZrO 2 , the Zr concentration in the third portion 103 is preferably higher than the Zr concentration in the fourth portion 104 . As a result, the three-phase interface in the third portion 103 can be further increased, so that the reaction resistance of the hydrogen electrode 2 can be further reduced.
　第３部分１０３及び第４部分１０４におけるＣｅ濃度、希土類元素濃度、Ｚｒ濃度及びＮｉ濃度は、上述した原子濃度プロファイルによるライン分析によって得られる。 The Ce concentration, rare earth element concentration, Zr concentration, and Ni concentration in the third portion 103 and the fourth portion 104 are obtained by line analysis using the atomic concentration profile described above.
　（実施形態の変形例）
　以上、本発明の実施形態について説明したが、本発明はこれらに限定されるものではなく、本発明の趣旨を逸脱しない限りにおいて種々の変更が可能である。 (Modified example of embodiment)
Although the embodiments of the present invention have been described above, the present invention is not limited to these, and various changes can be made without departing from the spirit of the present invention.
　上記実施形態では、燃料電池の一例として、いわゆる横縞型の燃料電池セルについて説明したが、電気化学セルはこれに限られない。本発明は、電解質層の両側に水素極と酸素極とが配置された電気化学セルに適用可能である。 In the above embodiment, a so-called horizontal striped fuel cell was described as an example of a fuel cell, but the electrochemical cell is not limited to this. The present invention is applicable to an electrochemical cell in which a hydrogen electrode and an oxygen electrode are arranged on both sides of an electrolyte layer.
　電気化学セルとは、電気エネルギーを化学エネルギーに変えるため、全体的な酸化還元反応から起電力が生じるように一対の電極が配置された素子と、化学エネルギーを電気エネルギーに変えるための素子との総称である。 An electrochemical cell consists of an element with a pair of electrodes arranged so that an electromotive force is generated from the overall redox reaction, and an element that converts chemical energy into electrical energy. It is a generic term.
　電気化学セルとしては、横縞型の燃料電池セルのほか、縦縞型の燃料電池セル、平板型の燃料電池セル、筒型の燃料電池セル、更に、水の電気分解反応を利用して水素の生成を行う電解セルなどが挙げられる。また、上記実施形態では、Ｏ２－（酸素イオン）をキャリアとしたが、ＯＨ－（水酸化物イオン）やプロトンをキャリアとしてもよい。 In addition to horizontal striped fuel cells, electrochemical cells include vertical striped fuel cells, flat plate fuel cells, cylindrical fuel cells, and hydrogen generation cells that utilize the electrolysis reaction of water. An example is an electrolytic cell that performs this. Furthermore, in the above embodiments, O 2 - (oxygen ions) are used as carriers, but OH - (hydroxide ions) or protons may be used as carriers.
　以下、本発明に係る電気化学セルの実施例について説明するが、本発明はこれらの実施例に限定されるものはない。 Examples of the electrochemical cell according to the present invention will be described below, but the present invention is not limited to these examples.
　（比較例）
　以下のようにして、比較例の燃料電池セルを作製した。なお、以下の燃料電池セルでは、支持基板の各主面上に、１０個の発電素子部を形成した。 (Comparative example)
A fuel cell of a comparative example was produced in the following manner. In addition, in the following fuel cell, 10 power generation element parts were formed on each main surface of the support substrate.
　まず、ＭｇＯ粉末、Ｙ２Ｏ３粉末、バインダー、造孔材、及び分散材をボールミルにて混合することにより支持基板形成用スラリーを調製した。この支持基板形成用スラリーを押し出し成形と切削によって支持基板の成形体を作成した。 First, a slurry for forming a support substrate was prepared by mixing MgO powder, Y 2 O 3 powder, binder, pore-forming material, and dispersion material in a ball mill. A molded body of a support substrate was created by extrusion molding and cutting this slurry for forming a support substrate.
　次に、ＮｉＯ粉末、Ｙ２Ｏ３粉末、バインダー、造孔材、及び分散材をボールミルにて混合することにより第１集電部用スラリーを調製した。この第１集電部用スラリーをスクリーン印刷法によって、支持基板の成形体の第１凹部内に塗布し、第１集電部の成形体を形成した。 Next, a slurry for the first current collector was prepared by mixing NiO powder, Y 2 O 3 powder, binder, pore-forming material, and dispersion material in a ball mill. This slurry for the first current collector was applied by screen printing into the first recess of the molded body of the support substrate to form the molded body of the first current collector.
　次に、ＮｉＯ粉末、ＹＳＺ粉末、バインダー、造孔材、及び分散材をボールミルにて混合することにより水素極用スラリーを調製した。この水素極用スラリーをスクリーン印刷法によって第１集電部の第２凹部内に塗布して、水素極の成形体を形成した。 Next, a slurry for a hydrogen electrode was prepared by mixing NiO powder, YSZ powder, binder, pore-forming material, and dispersing material in a ball mill. This hydrogen electrode slurry was applied to the second recess of the first current collector by screen printing to form a hydrogen electrode molded body.
　次に、ＬａＣｒＯ３粉末及びバインダーを添加し、ボールミルにて混合することにより、インターコネクタ用スラリーを調製した。このインターコネクタ用スラリーをスクリーン印刷法によって、第１集電部の第３凹部内に塗布し、インターコネクタの成形体を形成した。 Next, a slurry for an interconnector was prepared by adding LaCrO 3 powder and a binder and mixing in a ball mill. This interconnector slurry was applied to the third recess of the first current collector by screen printing to form a molded interconnector.
　次に、ＹＳＺ粉末及びバインダーをボールミルにて混合することにより電解質用スラリーを調製した。この電解質用スラリーをスクリーン印刷法によって、支持基板を覆うように塗布し、電解質の成形体を形成した。 Next, an electrolyte slurry was prepared by mixing the YSZ powder and the binder in a ball mill. This electrolyte slurry was applied to cover the supporting substrate by screen printing to form an electrolyte molded body.
　次に、ＧＤＣ粉末及びバインダーをボールミルにて混合することにより反応防止層用スラリーを調製した。この反応防止層用スラリーをスクリーン印刷法によって電解質の成形体上に塗布し、反応防止膜の成形体を形成した。 Next, a reaction prevention layer slurry was prepared by mixing the GDC powder and the binder in a ball mill. This reaction prevention layer slurry was applied onto the electrolyte molded body by screen printing to form a reaction prevention film molded body.
　次に、各成形体の積層体を共焼成（１３００℃、５時間）して、支持基板、第１集電部、水素極、インターコネクタ、電解質、及び反応防止層の共焼成体を作製した。 Next, the laminate of each molded body was co-fired (1300°C, 5 hours) to produce a co-fired body of the support substrate, first current collector, hydrogen electrode, interconnector, electrolyte, and reaction prevention layer. .
　次に、ＬＳＣＦ粉末、バインダー、造孔材、及び分散材をボールミルにて混合することにより酸素極用スラリーを調製した。この酸素極用スラリーをスクリーン印刷法によって反応防止膜上に塗布し、酸素極の成形体を形成した。 Next, a slurry for an oxygen electrode was prepared by mixing the LSCF powder, binder, pore forming material, and dispersing material in a ball mill. This oxygen electrode slurry was applied onto the reaction prevention film by screen printing to form a molded oxygen electrode.
　次に、ＬＳＣＦ粉末、バインダー、造孔材、及び分散材をボールミルにて混合することにより第２集電部用スラリーを調製した。この第２集電部形成用スラリーをスクリーン印刷法によって酸素極からインターコネクタまで塗布し、第２集電部の成形体を形成した。 Next, a slurry for the second current collector was prepared by mixing the LSCF powder, binder, pore-forming material, and dispersing material in a ball mill. This slurry for forming a second current collector was applied from the oxygen electrode to the interconnector by a screen printing method to form a molded body of the second current collector.
　次に、酸素極及び第２集電部の各成形体を焼成（１０５０℃、３時間）した。 Next, the molded bodies of the oxygen electrode and the second current collector were fired (1050°C, 3 hours).
　（実施例１～６）
　電解質を２層構造にしたこと以外は比較例と同様の工程にて実施例１～６の燃料電池セル（図１～３参照）を作製した。 (Examples 1 to 6)
Fuel cells of Examples 1 to 6 (see FIGS. 1 to 3) were produced in the same process as the comparative example except that the electrolyte had a two-layer structure.
　具体的には、ＹＳＺ粉末及びバインダーをボールミルにて混合することにより第１部分用スラリーを調製した。この際、ＹＳＺ粉末に含まれるＹ濃度を実施例ごとに変更することによって、表１に示すように第１部分におけるＹ濃度を調整した。そして、第１部分用スラリーをスクリーン印刷法によって、支持基板を覆うように塗布し、電解質のうち第１部分の成形体を形成した。 Specifically, the slurry for the first part was prepared by mixing the YSZ powder and the binder in a ball mill. At this time, the Y concentration in the first portion was adjusted as shown in Table 1 by changing the Y concentration contained in the YSZ powder for each example. Then, the slurry for the first portion was applied by screen printing so as to cover the support substrate, thereby forming a molded body of the first portion of the electrolyte.
　次に、ＹＳＺ粉末及びバインダーをボールミルにて混合することにより第２部分用スラリーを調製した。この際、ＹＳＺ粉末に含まれるＹ濃度を実施例ごとに変更することによって、表１に示すように、実施例１～５の第２部分におけるＹ濃度を比較例の電解質におけるＹ濃度と同じとし、実施例６の第２部分におけるＹ濃度を比較例の電解質におけるＹ濃度より低くした。そして、第２部分用スラリーをスクリーン印刷法によって、第１部分の成形体上に塗布し、電解質のうち第２部分の成形体を形成した。 Next, a slurry for the second portion was prepared by mixing the YSZ powder and the binder in a ball mill. At this time, by changing the Y concentration contained in the YSZ powder for each example, the Y concentration in the second part of Examples 1 to 5 was made the same as the Y concentration in the electrolyte of the comparative example, as shown in Table 1. , the Y concentration in the second portion of Example 6 was lower than the Y concentration in the electrolyte of the comparative example. Then, the slurry for the second portion was applied onto the molded body of the first portion by screen printing to form a molded body of the second portion of the electrolyte.
　（実施例７）
　水素極を２層構造にして第３部分のみにＺｒＯ２を添加したこと以外は実施例１と同様の工程にて実施例７の燃料電池セルを作製した。 (Example 7)
A fuel cell of Example 7 was fabricated using the same process as Example 1 except that the hydrogen electrode had a two-layer structure and ZrO 2 was added only to the third portion.
　具体的には、ＮｉＯ粉末、ＹＳＺ粉末、ＺｒＯ２粉末、バインダー、造孔材、及び分散材をボールミルにて混合することにより第３部分用スラリーを調製した。そして、第３部分用スラリーをスクリーン印刷法によって第１集電部の第２凹部内に塗布して、水素極のうち第３部分の成形体を形成した。 Specifically, a slurry for the third portion was prepared by mixing NiO powder, YSZ powder, ZrO 2 powder, binder, pore-forming material, and dispersion material in a ball mill. Then, the slurry for the third portion was applied into the second recess of the first current collector by screen printing to form a molded body for the third portion of the hydrogen electrode.
　次に、ＮｉＯ粉末、ＹＳＺ粉末、バインダー、造孔材、及び分散材をボールミルにて混合することにより第４部分用スラリーを調製した。そして、第４部分用スラリーをスクリーン印刷法によって第３部分の成形体上に塗布して、水素極のうち第４部分の成形体を形成した。 Next, a slurry for the fourth portion was prepared by mixing NiO powder, YSZ powder, binder, pore-forming material, and dispersing material in a ball mill. Then, the slurry for the fourth part was applied onto the molded body of the third part by a screen printing method to form a molded body of the fourth part of the hydrogen electrode.
　（実施例８～１２）
　水素極の第４部分にもＺｒＯ２を添加したこと以外は実施例７と同様の工程にて実施例８～１２の燃料電池セルを作製した。 (Examples 8 to 12)
Fuel cells of Examples 8 to 12 were produced in the same process as Example 7 except that ZrO 2 was also added to the fourth portion of the hydrogen electrode.
　具体的には、ＮｉＯ粉末、ＹＳＺ粉末、ＺｒＯ２粉末、バインダー、造孔材、及び分散材をボールミルにて混合することにより第３部分用スラリーを調製した。この際、ＺｒＯ２粉末に含まれるＺｒ濃度を実施例ごとに変更することによって、表１に示すように第３部分におけるＺｒ濃度を調整した。そして、第３部分用スラリーをスクリーン印刷法によって第１集電部の第２凹部内に塗布して、水素極のうち第３部分の成形体を形成した。 Specifically, a slurry for the third portion was prepared by mixing NiO powder, YSZ powder, ZrO 2 powder, binder, pore-forming material, and dispersion material in a ball mill. At this time, the Zr concentration in the third portion was adjusted as shown in Table 1 by changing the Zr concentration contained in the ZrO 2 powder for each example. Then, the slurry for the third portion was applied into the second recess of the first current collector by screen printing to form a molded body for the third portion of the hydrogen electrode.
　次に、ＮｉＯ粉末、ＹＳＺ粉末、ＺｒＯ２粉末、バインダー、造孔材、及び分散材をボールミルにて混合することにより第４部分用スラリーを調製した。ＺｒＯ２粉末の添加量は、実施例７の第３部分と同じとした。そして、第４部分用スラリーをスクリーン印刷法によって第３部分の成形体上に塗布して、水素極のうち第４部分の成形体を形成した。 Next, a slurry for the fourth portion was prepared by mixing NiO powder, YSZ powder, ZrO 2 powder, binder, pore-forming material, and dispersion material in a ball mill. The amount of ZrO 2 powder added was the same as in the third part of Example 7. Then, the slurry for the fourth part was applied onto the molded body of the third part by a screen printing method to form a molded body of the fourth part of the hydrogen electrode.
　（初期性能評価）
　比較例及び実施例１～１２の燃料電池セルを７５０℃まで昇温させた状態で、水素極に水蒸気及び水素の混合ガス（混合比５０：５０）を供給するとともに酸素極に空気を供給した。続いて、０．５Ａ／ｃｍ２の電流値を掃引しながら、電流遮断法を用いて、全過電圧から抵抗過電圧を差し引いた反応過電圧を取得した。そして、比較例の反応過電圧を基準とし、下記（３）式を用いて、反応過電圧抑制率を算出した。 (Initial performance evaluation)
While the fuel cells of Comparative Examples and Examples 1 to 12 were heated to 750° C., a mixed gas of water vapor and hydrogen (mixing ratio 50:50) was supplied to the hydrogen electrode, and air was supplied to the oxygen electrode. . Subsequently, while sweeping the current value of 0.5 A/cm 2 , the reaction overvoltage was obtained by subtracting the resistance overvoltage from the total overvoltage using the current interruption method. Then, using the reaction overvoltage of the comparative example as a reference, the reaction overvoltage suppression rate was calculated using the following equation (3).
　各実施例の反応過電圧抑制率（％）＝１００×（（比較例の反応過電圧）－（各実施例の反応過電圧））/（比較例の反応過電圧）・・・（３） Reaction overvoltage suppression rate (%) of each example = 100 × ((reaction overvoltage of comparative example) - (reaction overvoltage of each example)) / (reaction overvoltage of comparative example)... (3)
　算出した反応過電圧抑制率の値とその評価を表１に示した。表１では、反応過電圧抑制率が２５％以上であった場合を「Ａ」と評価し、２０％以上２５％未満であった場合を「Ｂ」と評価し、１０％以上２０％未満であった場合を「Ｃ」と評価し、１０％未満であった場合を「Ｄ」と評価した。 The calculated reaction overvoltage suppression rate values and their evaluations are shown in Table 1. In Table 1, when the reaction overvoltage suppression rate is 25% or more, it is evaluated as "A", when it is 20% or more and less than 25%, it is evaluated as "B", and when it is 10% or more and less than 20%, it is evaluated as "B". The case where it was less than 10% was evaluated as "C", and the case where it was less than 10% was evaluated as "D".
　（熱サイクル試験）
　水素極にＡｒ及び水素の混合ガス（水素はＡｒに対して４％）を供給することで還元雰囲気に維持した状態で、常温から７５０℃まで２時間で昇温した後に４時間で常温まで降温させる工程を１サイクルとして１０回繰り返した。 (Heat cycle test)
While maintaining a reducing atmosphere by supplying a mixed gas of Ar and hydrogen (hydrogen: 4% to Ar) to the hydrogen electrode, the temperature was raised from room temperature to 750°C in 2 hours, and then cooled down to room temperature in 4 hours. This step was repeated 10 times as one cycle.
　その後、水素極の断面をＦＥ－ＳＥＭで観察して、長さ３μｍ以上クラックが水素極に発生しているか否かを確認した。表１では、水素極にクラックが発生していないもの、及びクラックが発生していても３μｍ未満であったものを「〇」と評価し、水素極に３μｍ以上のクラックが発生したものを「△」と評価した。 Thereafter, the cross section of the hydrogen electrode was observed using FE-SEM to confirm whether or not a crack with a length of 3 μm or more had occurred in the hydrogen electrode. In Table 1, those with no cracks on the hydrogen electrode and those with cracks less than 3 μm in size are evaluated as "○", and those with cracks on the hydrogen electrode with a size of 3 μm or more are evaluated as " The evaluation was ``△''.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示すように、電解質を２層構造にし、かつ、第１部分におけるＹ濃度を第２部分におけるＹ濃度より高くした実施例１～１２では、比較例に比べて初期性能を向上させることができた。このような結果が得られたのは、電解質のうち水素極に接続される第１部分のイオン伝導性を向上させ、かつ、水素極のうち電解質近傍における三相界面のイオン伝導性を向上させられたためである。 As shown in Table 1, in Examples 1 to 12, in which the electrolyte had a two-layer structure and the Y concentration in the first part was higher than the Y concentration in the second part, the initial performance was improved compared to the comparative example. was completed. These results were obtained by improving the ionic conductivity of the first part of the electrolyte connected to the hydrogen electrode, and by improving the ionic conductivity of the three-phase interface near the electrolyte in the hydrogen electrode. This is because it was done.
　また、第１部分におけるＹ濃度を４．５ｍｏｌ％以上７．０ｍｏｌ％以下とした実施例２～４，６では、実施例１，５に比べて初期性能をより向上させることができた。 Furthermore, in Examples 2 to 4 and 6, in which the Y concentration in the first portion was set to 4.5 mol% or more and 7.0 mol% or less, the initial performance was able to be further improved compared to Examples 1 and 5.
　また、水素極の第３部分が希土類元素の添加されたセリア系酸化物及びＺｒＯ２の固溶体とＮｉとを含む実施例７，８では、実施例１に比べて初期性能をより向上させることができた。このような結果が得られたのは、第３部分１０３において三相界面（反応場）を増大できたためである。なお、希土類元素の添加されたセリア系酸化物及びＺｒＯ２の固溶体が第３部分に存在することは、ＥＤＸ（エネルギー分散型Ｘ線分析装置）を用いた面分析による元素マッピングでＺｒとＣｅＯ２が同じ位置で観察されることをもって確認した。 Furthermore, in Examples 7 and 8, in which the third portion of the hydrogen electrode includes a ceria-based oxide to which a rare earth element is added, a ZrO 2 solid solution, and Ni, the initial performance can be further improved compared to Example 1. did it. This result was obtained because the three-phase interface (reaction field) could be increased in the third portion 103. The existence of the ceria-based oxide containing rare earth elements and the solid solution of ZrO2 in the third part was confirmed by elemental mapping by area analysis using EDX (energy dispersive X-ray spectrometer) . This was confirmed by being observed at the same location.
　また、水素極の第４部分が希土類元素の添加されたセリア系酸化物及びＺｒＯ２の固溶体とＮｉとを含む実施例８～１２では、実施例１に比べて熱サイクル試験における耐久性を向上させることができた。このような結果が得られたのは、ＺｒＯ２の添加によって第４部分におけるセリア系酸化物の骨格を強化できたためである。なお、希土類元素の添加されたセリア系酸化物及びＺｒＯ２の固溶体が第２部分に存在することは、ＥＤＸを用いた面分析による元素マッピングでＺｒとＣｅＯ２が同じ位置で観察されることをもって確認した。 Furthermore, in Examples 8 to 12, in which the fourth part of the hydrogen electrode includes a ceria-based oxide to which a rare earth element is added, a ZrO 2 solid solution, and Ni, the durability in the thermal cycle test is improved compared to Example 1. I was able to do it. This result was obtained because the addition of ZrO 2 strengthened the ceria-based oxide skeleton in the fourth portion. The existence of the rare earth element-doped ceria-based oxide and ZrO 2 solid solution in the second part is confirmed by the fact that Zr and CeO 2 are observed at the same position in elemental mapping by surface analysis using EDX. confirmed.
　また、水素極の第３部分及び第４部分の両方がＺｒＯ２を含み、かつ、第３部分におけるジルコニウム濃度を第４部分におけるジルコニウム濃度より高くした実施例９～１２では、実施例７，８に比べて初期性能をより向上させることができた。このような結果が得られたのは、第３部分における三相界面をより増大できたためである。 Furthermore, in Examples 9 to 12, in which both the third and fourth parts of the hydrogen electrode contained ZrO 2 and the zirconium concentration in the third part was higher than the zirconium concentration in the fourth part, Examples 7 and 8 We were able to improve the initial performance compared to . This result was obtained because the three-phase interface in the third portion could be further increased.
　さらに、実施例９～１２のうち、第３部分におけるジルコニウム濃度を５ｍｏｌ％以上１５ｍｏｌ％以下とした実施例１０，１１では、初期性能を更に向上させることができた。 Further, among Examples 9 to 12, in Examples 10 and 11 in which the zirconium concentration in the third portion was 5 mol% or more and 15 mol% or less, the initial performance could be further improved.
１０　　燃料電池セル
２０　　支持基板
３０　　発電素子部
１　　　第１集電部
２　　　水素極
１０３　第３部分
１０４　第４部分
３　　　電解質
１０１　第１部分
１０２　第２部分
４　　　反応防止層
５　　　酸素極
６　　　第２集電部
７　　　インターコネクタ 10 Fuel cell 20 Support substrate 30 Power generation element section 1 First current collector 2 Hydrogen electrode 103 Third section 104 Fourth section 3 Electrolyte 101 First section 102 Second section 4 Reaction prevention layer 5 Oxygen electrode 6 Second current collector Part 7 Interconnector

Claims (6)

  1. 　水素極と、
    　酸素極と、
    　前記水素極及び前記酸素極の間に配置される電解質と、
    　前記酸素極と前記電解質との間に配置される反応防止層と、
    を備え、
    　前記電解質は、水素極側表面から３μｍ以内の第１部分と、前記水素極側表面から３μｍ超の第２部分とを有し、
    　前記第１部分及び前記第２部分それぞれは、イットリア安定化ジルコニアを含み、
    　前記第１部分におけるイットリウム濃度は、前記第２部分におけるイットリウム濃度より高い、
    電気化学セル。     hydrogen electrode,
    an oxygen electrode,
    an electrolyte disposed between the hydrogen electrode and the oxygen electrode;
    a reaction prevention layer disposed between the oxygen electrode and the electrolyte;
    Equipped with
    The electrolyte has a first portion within 3 μm from the surface on the hydrogen electrode side, and a second portion over 3 μm from the surface on the hydrogen electrode side,
    each of the first portion and the second portion includes yttria-stabilized zirconia;
    The yttrium concentration in the first portion is higher than the yttrium concentration in the second portion.
    electrochemical cell.
  2. 　前記第１部分におけるイットリウム濃度は、４．５ｍｏｌ％以上７．０ｍｏｌ％以下である、
    請求項１に記載の電気化学セル。     The yttrium concentration in the first portion is 4.5 mol% or more and 7.0 mol% or less,
    An electrochemical cell according to claim 1.
  3. 　前記水素極は、電解質側表面から１０μｍ以内の第３部分と、前記電解質側表面から１０μｍ超の第４部分とを有し、
    　前記第３部分は、希土類元素が添加されたセリア系酸化物及びジルコニアの固溶体と、ニッケルとを含む、
    請求項１又は２に記載の電気化学セル。     The hydrogen electrode has a third portion within 10 μm from the electrolyte side surface and a fourth portion more than 10 μm from the electrolyte side surface,
    The third portion includes a solid solution of ceria-based oxide and zirconia to which a rare earth element is added, and nickel.
    The electrochemical cell according to claim 1 or 2.
  4. 　前記第４部分は、希土類元素が添加されたセリア系酸化物及びジルコニアの固溶体と、ニッケルとを含む、
    請求項１又は２に記載の電気化学セル。     The fourth portion includes a solid solution of ceria-based oxide and zirconia to which a rare earth element is added, and nickel.
    The electrochemical cell according to claim 1 or 2.
  5. 　前記第３部分におけるジルコニウム濃度は、前記第４部分におけるジルコニウム濃度より高い、
    請求項４に記載の電気化学セル。     The zirconium concentration in the third portion is higher than the zirconium concentration in the fourth portion.
    The electrochemical cell according to claim 4.
  6. 　前記第３部分におけるジルコニウム濃度は、５．０ｍｏｌ％以上１５ｍｏｌ％以下である、
    請求項５に記載の電気化学セル。     The zirconium concentration in the third portion is 5.0 mol% or more and 15 mol% or less,
    The electrochemical cell according to claim 5.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0757746A (en) * 1993-08-06 1995-03-03 Fujikura Ltd Electrode structure of solid electrolytic fuel cell
JPH08213029A (en) * 1995-02-06 1996-08-20 Fujikura Ltd Fuel electrode of solid electrolyte fuel cell
JP2004362913A (en) * 2003-06-04 2004-12-24 Nissan Motor Co Ltd Electrolyte for solid oxide fuel cell, and manufacturing method of the same
JP2010027457A (en) * 2008-07-22 2010-02-04 Mitsubishi Heavy Ind Ltd Power generation membrane of solid electrolyte fuel cell, and solid electrolyte fuel cell equipped with the same, as well as method of manufacturing power generation membrane of solid electrolyte fuel cell
JP2013101907A (en) * 2011-10-14 2013-05-23 Ngk Insulators Ltd Fuel cell

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0757746A (en) * 1993-08-06 1995-03-03 Fujikura Ltd Electrode structure of solid electrolytic fuel cell
JPH08213029A (en) * 1995-02-06 1996-08-20 Fujikura Ltd Fuel electrode of solid electrolyte fuel cell
JP2004362913A (en) * 2003-06-04 2004-12-24 Nissan Motor Co Ltd Electrolyte for solid oxide fuel cell, and manufacturing method of the same
JP2010027457A (en) * 2008-07-22 2010-02-04 Mitsubishi Heavy Ind Ltd Power generation membrane of solid electrolyte fuel cell, and solid electrolyte fuel cell equipped with the same, as well as method of manufacturing power generation membrane of solid electrolyte fuel cell
JP2013101907A (en) * 2011-10-14 2013-05-23 Ngk Insulators Ltd Fuel cell

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