JP7510669B2 - Fuel electrode for solid oxide cell, laminated structure and manufacturing method thereof, and solid oxide cell and manufacturing method thereof - Google Patents

Description

The present invention relates to a fuel electrode for a solid oxide cell, a laminated structure and its manufacturing method, and a solid oxide cell and its manufacturing method.

Research and development is currently underway into solid oxide cells, with the aim of putting them to practical use as devices that enable highly efficient energy conversion. Representative examples of devices that use solid oxide cells include solid oxide fuel cells and solid oxide electrolysis cells. Solid oxide cells consist of a dense electrolyte, primarily made of oxide, sandwiched between two porous electrodes, the air electrode and the fuel electrode.

Solid oxide cells can be used in a wide range of operating temperatures, from 400 to 1000°C, depending on the constituent materials.

The ions that act as charge carriers are mainly oxide ions and protons. Electrolyte materials that conduct oxide ions are called oxide-ion conductive electrolytes, and electrolyte materials that conduct protons are called proton conductive electrolytes. Representative examples of oxide-ion conductive electrolytes include zirconia-based and ceria-based materials, while representative examples of proton conductive electrolytes include perovskite-type oxide materials.

The electrode material is an electronically conductive oxide or metal with catalytic activity (hereinafter referred to as "electronically conductive material"). Although the electronically conductive material may be used alone, it may be mixed with the electronically conductive material and an ionically conductive material that conducts the same ions as the electrolyte ("ions" is a general term for all ions that become conductive carriers, including oxide ions and protons) to expand the reaction field of the electrode, adjust the thermal expansion coefficient, and improve the mechanical strength. In general, the reaction resistance of the electrode is reduced by mixing an electronically conductive material with an ionically conductive material. The reaction resistance depends on the size of the reaction field (or the amount of reactive active sites) per unit area of the electrode and the activity per reaction field.

When an electronically conductive material and an ionically conductive material are mixed, the mixture is called a composite when at least one of the materials has an average particle size of 1 μm or less. By combining the materials, the effect of reducing the reaction resistance of the electrode can be significantly achieved.

Because the electrode is porous, it is possible to supply the gas required for the electrochemical reaction to the reaction field within the electrode and to remove the gas generated by the electrochemical reaction (hereinafter, the supply and removal of gas will be referred to as "gas diffusion"). The resistance within the electrode that arises due to gas diffusion is called gas diffusion resistance. In practice, for gas to diffuse, the pores must be open pores through which the gas can move, and for this to occur, the porosity of the electrode must be at least 15% by volume or more. In actual electrode design, the porosity is often set to about 40% by volume to sufficiently reduce gas diffusion resistance.

The combined resistance of the electrode reaction and gas diffusion resistance is called the electrode resistance.

Examples of electronically conductive materials for the air electrode of a solid oxide cell include perovskite-type oxide materials, such as (LaSr)MnO ₃ , (LaSr)FeO ₃ , (LaSr)CoO ₃ , (LaSr)(CoFe)O ₃ , etc. La in the above electronically conductive materials can be substituted or partially substituted with other lanthanides (Pr, Sm, Gd), and Sr can be substituted or partially substituted with other alkaline earth metals (Ca, Ba).

Metallic materials (Ti, Mn, Fe, Co, Ni, Cu, etc.) are used as electronically conductive materials for the fuel electrode of solid oxide cells. Metallic materials include those that are reduced by gases such as hydrogen, carbon monoxide, hydrocarbons, and biofuels. For example, if NiO (oxide) is used as a manufacturing material, the NiO is reduced to Ni (metal) when the solid oxide cell is constructed and operated by the gases.

One of the important issues for the widespread use of solid oxide cells is improving the energy conversion performance per unit volume, which directly translates into cost reduction. An important factor in the energy conversion performance per unit volume of solid oxide cells is the current per unit area of the electrode (hereafter referred to as "current density"). Currently, various research and development efforts are underway with the aim of increasing the current density.

The dominant factor that determines the current density of a solid oxide cell is the electrode resistance mentioned above. Overvoltage (the voltage difference between the equilibrium state and the operating state) occurs due to electrochemical reactions and gas diffusion that occur at the electrodes, but from the perspective of highly efficient operation, electrodes with low electrode resistance are required that can obtain high current density even with low overvoltage.

In particular, the fuel electrode is manufactured by sintering at a higher temperature than the air electrode, and grain growth occurs, reducing the surface area available for reaction (reaction field), which increases the electrode resistance, which has been an issue.

Previous research and development has disclosed, for example, that the electrode resistance of the fuel electrode can be reduced by controlling the average particle size of the electronically conductive material and the ionically conductive material (Patent Document 1). In addition, a fuel electrode has been disclosed in which the electrode resistance is reduced by mixing an electronically conductive material and an ionically conductive material and then increasing the porosity and pore size, thereby enabling a high current density to be obtained (Patent Document 2). Although a certain degree of effect has been confirmed, in order to reduce the cost of solid oxide cells and promote their widespread use, a technology to further reduce the electrode resistance of the fuel electrode was needed.

JP 2013-152915 A JP 2016-183094 A

As described above, in order to reduce the cost and promote the widespread use of solid oxide cells, it is necessary to dramatically reduce electrode resistance compared to conventional technology. And as mentioned above, there is a demand to further reduce electrode resistance and achieve higher current density.

Therefore, the present invention aims to provide a fuel electrode for a solid oxide cell that has low electrode resistance. The present invention also aims to provide a solid oxide cell that achieves high current density.

In order to realize a fuel electrode that can significantly reduce the electrode resistance, the inventors produced many prototype fuel electrode samples by controlling the material and structure of the fuel electrode and repeatedly evaluated their performance. As a result, they discovered that the electrode resistance of the fuel electrode can be dramatically reduced by using a fuel electrode material that contains an electronic conductive material and an ion conductive material, each of which has a specific particle size and a specific particle size distribution, and that the electrode resistance of the fuel electrode can be further reduced by giving the fuel electrode a specific film thickness or a specific porosity, which led to the development of the present invention.

To solve the above problems, the present invention has the following features:

(1) A fuel electrode for a solid oxide cell, comprising:
The present invention is directed to a sintered body of a raw material containing an electronic conductive material and an ion conductive material,
The average particle size of the electron conductive material is 0.001 to 2.00 μm, and the average particle size of the ion conductive material is 0.001 to 2.00 μm;
When the standard deviation of the particle size distribution of the electron conductive material is A ₁ (μm) and the average particle size of the electron conductive material is B ₁ (μm), the value of (A ₁ /B ₁ )×100 is 0.000 to 20.0,
the standard deviation of the particle size distribution of the ion-conductive material is A ₂ (μm) and the average particle size of the ion-conductive material is B ₂ (μm), the value of (A ₂ /B ₂ )×100 is 0.000 to 20.0;
A fuel electrode for a solid oxide cell, comprising:
(2) The fuel electrode for a solid oxide cell according to claim 1, characterized in that the thickness of the electrode is 1.0 μm to 100.0 μm and the porosity is 15 to 40% by volume.
(3) The electron conductive material is at least one metal or metal oxide including at least one selected from the group consisting of Ni, Cu, Fe, Co, Mn, Cr, La, Sm, Gd, Ce, Pr, Sr, Ca, and Ba;
the ion conductive material is at least one metal oxide containing at least one selected from the group consisting of Sc, Sr, Zr, Y, Ba, Ce, Sm, Gd, and Yb;
the mass ratio of the electronic conductive material to the ion conductive material (mass of the electronic conductive material:mass of the ion conductive material) is 80:20 to 40:60;
2. The solid oxide cell fuel electrode according to claim 1,
(4) An electrolyte and a solid oxide cell fuel electrode according to any one of claims 1 to 3 laminated with the electrolyte,
the membrane thickness of the electrolyte is 0.1 to 20.0 μm, and the electrolyte is a dense body having a relative density of 95 to 100%;
A laminated structure comprising:
(5) A porous support and a solid oxide cell fuel electrode according to any one of claims 1 to 3 laminated on the porous support,
the porosity of the porous support is higher than the porosity of the solid oxide cell anode;
A laminated structure comprising:
(6) A solid oxide cell comprising the fuel electrode according to any one of claims 1 to 3.
(7) A solid oxide cell comprising the laminated structure according to claim 4 or 5.
(8) A method for producing a laminated structure, comprising the steps of applying a first slurry for producing the solid oxide cell fuel electrode onto a porous support, applying a second slurry for producing the electrolyte onto the porous support, and then firing the resulting mixture at a first temperature to form a porous support, a fuel electrode, and an electrolyte.
(9) applying a first slurry for preparing the solid oxide cell anode onto a porous support, then applying a second slurry for preparing the electrolyte onto the porous support, and then firing the first slurry at a first temperature to form a porous support, an anode, and an electrolyte;
applying a third slurry for forming an intermediate layer on the formed electrolyte, and then firing the third slurry at a second temperature to form the intermediate layer;
applying a fourth slurry for producing an air electrode onto the formed intermediate layer, and then firing the resulting mixture at a third temperature to form an air electrode;
2. A method for producing a solid oxide cell comprising the steps of:
In this specification, when a numerical range is indicated using "to", the numerical range includes both ends of the range.

The present invention can provide a fuel electrode with low electrode resistance. In addition, the present invention can provide a solid oxide cell that achieves high current density.

FIG. 2 is a schematic cross-sectional view of a laminated structure of a fuel electrode and an electrolyte according to an embodiment. FIG. 2 is a schematic cross-sectional view of a laminated structure of an anode and a porous support according to an embodiment. FIG. 2 is a schematic cross-sectional view of a laminated structure of an electrolyte, a fuel electrode, and a porous support according to an embodiment. FIG. 2 is a cross-sectional schematic view of a solid oxide cell according to the embodiment. Power generation characteristics of Example 2 Cole-Cole Plot of Example 2 Ultra-low accelerating voltage scanning electron microscope (LV-SEM) images of cross sections of solid oxide cells of Examples 1 to 3 and Comparative Example 1 LV-SEM image of a cross section of the electrolyte portion of Example 2

The solid oxide cell electrode of the present invention, the solid oxide cell using the same, and the manufacturing method thereof will be described below based on the embodiments and examples. Note that in this specification, when a numerical range is indicated using "~", the numerical values at both ends are included.

The solid oxide cell fuel electrode of the present invention is a solid oxide cell fuel electrode,
The present invention is made of a sintered body of a raw material containing an electronic conductive material and an ion conductive material,
The average particle size of the electron conductive material is 0.001 to 2.00 μm, and the average particle size of the ion conductive material is 0.001 to 2.00 μm;
When the standard deviation of the particle size distribution of the electron conductive material is A ₁ (μm) and the average particle size of the electron conductive material is B ₁ (μm), the value of (A ₁ /B ₁ )×100 is 0.000 to 20.0,
the standard deviation of the particle size distribution of the ion-conductive material is A ₂ (μm) and the average particle size of the ion-conductive material is B ₂ (μm), the value of (A ₂ /B ₂ )×100 is 0.000 to 20.0;
The present invention relates to a fuel electrode for a solid oxide cell.

Figure 1 shows a schematic cross section of an electrode according to an embodiment of the present invention. The fuel electrode of this embodiment is porous and has pores for gas diffusion (fuel electrode 1). The fuel electrode 1 contains an electronic conductive material 2 and an ion conductive material 3. The porosity of the fuel electrode 1 is 15 to 40 volume %. The porosity can be measured by image processing using image analysis software based on the contrast of a cross-sectional SEM image of the porous electrode, and the area of the pores when the area of the image analysis target is set to 100% is the porosity (volume %) (porosity (volume %) = pore area ÷ area of image analysis target × 100).

As shown in FIG. 1, the fuel electrode 1 is formed as a laminated structure with the electrolyte 4, which is an ion-conductive material. The electrolyte 4 has a dense layer to prevent gas cross leakage. The entire electrolyte 4 may be dense. The relative density of the dense layer of the electrolyte 4 to the true density (mass) is 95 to 100%, more preferably 97 to 100%, and particularly preferably 98 to 100%. This is because the gas cross leakage prevention function can be further improved. In addition, the thickness of the dense layer of the electrolyte 4 is 0.1 μm to 20.0 μm, more preferably 0.1 μm to 10.0 μm, and particularly preferably 0.1 μm to 5.0 μm. This is because the resistance of the dense layer of the electrolyte 4 can be reduced while maintaining the gas cross leakage prevention function. In order to make the electrolyte 4 thin while preventing gas cross leakage, it is desirable for the entire electrolyte 4 to be dense. The relative density is measured by image processing using image analysis software based on the contrast of the cross-sectional SEM image of the electrolyte, and the area of the electrolyte when the area of the image analysis target is set to 100% is the relative density (%) (relative density (%) = area of electrolyte ÷ area of image analysis target × 100).

In order to improve mechanical strength without impairing gas diffusivity, the fuel electrode 1 is formed on a porous support 5 having a higher porosity than the fuel electrode 1, as in the laminated structure shown in Figure 2. This allows the fuel electrode 1 to be formed as a specialized electrode (called an active layer, catalyst layer, functional layer, etc.) for reducing electrode resistance.

Figure 3 shows a schematic cross-sectional view of a laminated structure according to an embodiment of the present invention. A fuel electrode 1 is formed on a porous support 5, and an electrolyte 4 is formed on the fuel electrode 1. This makes it possible to form a laminated structure that combines the electrolyte 4's function of preventing gas cross-leakage, the fuel electrode 1's function of reducing the electrode resistance, and the porous support 5's function of improving the gas diffusion and electrical current collection properties.

The fuel electrode for solid oxide cells of the present invention is a porous body in which an electronically conductive material and an ionically conductive material are composited. The fuel electrode for solid oxide cells of the present invention is made of a sintered body of raw materials containing an electronically conductive material and an ionically conductive material. In other words, the fuel electrode for solid oxide cells of the present invention contains an electronically conductive material and an ionically conductive material, and is a sintered product obtained by sintering a raw material mixture containing a powdered electronically conductive material and a powdered ionically conductive material.

The electronically conductive material for the fuel electrode refers to a material that can be used in a high-temperature reducing atmosphere, has catalytic activity for the oxidation or reduction reaction of the gas on the fuel electrode side, and has the property of conducting electrons, including materials that are reduced to metals during operation. There are no particular limitations on the electronically conductive material for the fuel electrode, and examples of the electronically conductive material include iron, nickel, and copper. The electronically conductive material for the fuel electrode may be a single type or a combination of two or more types.

A more specific example of an electronically conductive material is a material consisting of one or more metals or metal oxides including one or more selected from the group consisting of Ni, Cu, Fe, Co, Mn, Cr, La, Sm, Gd, Ce, Pr, Sr, Ca, and Ba.

Nickel is a preferred electronically conductive material for the fuel electrode.

An ionically conductive material for a fuel electrode refers to a material that can be used in a high-temperature reducing atmosphere and has the property of conducting ions. There are no particular limitations on the ionically conductive material for a fuel electrode, and examples of the material include oxides based on zirconia, ceria, etc. The ionically conductive material for a fuel electrode may be one type alone or a combination of two or more types.

A more specific example of an ion-conductive material is a material consisting of one or more metal oxides containing one or more selected from the group consisting of Sc, Sr, Zr, Y, Ba, Ce, Sm, Gd, and Yb.

As the ion-conducting material for the anode, ZrO ₂ (Y ₂ O ₃ ) stabilized ZrO ₂ , (Sc ₂ O ₃ ) stabilized ZrO ₂ , Sm-doped CeO ₂ , Gd-doped CeO ₂ are preferred.

The average particle size of the primary particles of the electronic conductive material in the solid oxide cell fuel electrode of the present invention is 0.001 to 2.00 μm, preferably 0.005 to 1.00 μm, and particularly preferably 0.010 to 0.50 μm. The average particle size of the primary particles of the ion conductive material in the solid oxide cell fuel electrode of the present invention is 0.001 to 2.00 μm, preferably 0.005 to 1.00 μm, and particularly preferably 0.010 to 0.50 μm. When the average particle size of the primary particles of the electronic conductive material and the ion conductive material is within the above range, the contact points between the electronic conductive material and the ion conductive material increase and the specific surface area in the electrode increases, expanding the reaction field and lowering the electrode resistance.

In this specification, particle size refers to the particle size of the primary particle unless otherwise specified.

In addition, in the present invention, the average particle size of the primary particles is calculated by X-ray diffraction (e.g., SmartLab, manufactured by Rigaku) and Scherrer's formula (Scherrer constant: 0.9) when the primary particle size is smaller than approximately 100 nm, and is determined by observing the cross section of the electrode with a SEM (e.g., Ultra55, manufactured by Carl Zeiss) and analyzing the SEM image when the primary particle size is larger than approximately 100 nm. Note that the modulus when determining the standard deviation of the particle size distribution and the average particle size by analyzing the SEM image is 100 or more.

In the solid oxide cell fuel electrode of the present invention, when the standard deviation of the particle size distribution of the electronic conductive material is A ₁ (μm) and the average particle size of the electronic conductive material is B ₁ (μm), the value of (A ₁ /B ₁ ) × 100, i.e., (standard deviation of the particle size distribution of the electronic conductive material (A ₁ )/average particle size of the electronic conductive material (B ₁ )) × 100, is 0.000 to 20.0, preferably 0.001 to 15.0, and particularly preferably 0.1 to 10.0.

In the solid oxide cell fuel electrode of the present invention, when the standard deviation of the particle size distribution of the ion conductive material is A ₂ (μm) and the average particle size of the ion conductive material is B ₂ (μm), the value of (A ₂ /B ₂ ) × 100, i.e., (standard deviation of the particle size distribution of the ion conductive material (A ₂ )/average particle size of the ion conductive material (B ₂ )) × 100, is 0.000 to 20.0, preferably 0.001 to 15.0, and particularly preferably 0.1 to 10.0.

In the solid oxide cell fuel electrode of the present invention, the value of "(standard deviation of particle size distribution/average particle size) x 100" of the electronically conductive material and the ionically conductive material is within the above range, so that the number of particles (especially large particles) that deviate significantly from the average particle size can be reduced, and the reaction field is expanded by increasing the contact points and the specific surface area within the electrode, thereby lowering the electrode resistance.

In the fuel electrode for solid oxide cells of the present invention, the mass ratio of the electronically conductive material to the ionically conductive material (mass of the electronically conductive material:mass of the ionically conductive material) is preferably 80:20 to 40:60, preferably 70:30 to 50:50, and particularly preferably 65:35 to 55:45. By having the mass ratio of the electronically conductive material to the ionically conductive material in the fuel electrode within the above range, the number of contact points between the electronically conductive material and the ionically conductive material increases, expanding the reaction field and lowering the electrode resistance.

The solid oxide cell fuel electrode of the present invention may contain materials other than the electronically conductive material and the ionically conductive material, and the content of the materials other than the electronically conductive material and the ionically conductive material contained in the solid oxide cell fuel electrode of the present invention is in the range of 0 to 20 parts by mass when the combined mass of the electronically conductive material and the ionically conductive material is 100 parts by mass.

The thickness of the fuel electrode for solid oxide cells of the present invention is preferably 1.0 μm to 100.0 μm, more preferably 1.0 μm to 30.0 μm, and particularly preferably 1.0 μm to 10.0 μm. By having the thickness of the fuel electrode within the above range, gas diffusion resistance is reduced, resulting in low electrode resistance.

The porosity of the fuel electrode for solid oxide cells of the present invention is preferably 15 to 40% by volume, more preferably 18 to 38% by volume, and particularly preferably 20 to 35% by volume. By having the porosity of the fuel electrode within the above range, the occupancy rate per space of the electronically conductive material and the ionically conductive material in the electrode is increased while maintaining gas diffusibility, expanding the reaction field, and thus reducing the electrode resistance.

The laminate structure of the first embodiment of the present invention comprises an electrolyte and the solid oxide cell fuel electrode of the present invention laminated with the electrolyte,
The electrolyte has a film thickness of 0.1 to 20.0 μm, and is a dense body having a relative density of 95 to 100%;
The laminated structure is characterized by the above.

A laminate structure according to a second embodiment of the present invention comprises a porous support and the solid oxide cell fuel electrode of the present invention laminated on the porous support,
the porosity of the porous support is higher than the porosity of the solid oxide cell anode;
The laminated structure is characterized by the above.

The method for producing a laminated structure of the present invention is characterized by having a step of applying a first slurry for producing the fuel electrode for the solid oxide cell onto a porous support, then applying a second slurry for producing the electrolyte, and then firing at a first temperature to form a porous support, a fuel electrode, and an electrolyte.

The solid oxide cell of the present invention is a solid oxide cell characterized by having the solid oxide cell fuel electrode of the present invention.

The solid oxide cell of the present invention is characterized by having a laminated structure of the first or second embodiment of the present invention.

The method for producing a solid oxide cell of the present invention includes the steps of: applying a first slurry for producing the solid oxide cell fuel electrode onto a porous support; applying a second slurry for producing the electrolyte; and firing the applied slurry at a first temperature to form a porous support, a fuel electrode, and an electrolyte.
applying a third slurry for forming an intermediate layer on the formed electrolyte, and then firing the third slurry at a second temperature to form the intermediate layer;
applying a fourth slurry for producing an air electrode onto the formed intermediate layer, and then firing the resulting mixture at a third temperature to form an air electrode;
The present invention relates to a method for producing a solid oxide cell, comprising the steps of:

The material for forming the electrolyte refers to a material that has the property of conducting ions such as oxide ions and protons. The material for the electrolyte is not particularly limited, and examples include oxides with oxide ion conductivity such as zirconia-based oxides and ceria-based oxides, and oxides with proton conductivity such as perovskite-type oxides. The material for the electrolyte may be one type alone or a combination of two or more types.

More specific examples of the electrolyte material include a material made of one or more metals or metal oxides containing one or more selected from the group consisting of Ca, Sc, Sr, Ga, Y, Zr, In, Ba, La, Ce, Pr, Sm, Gd, and Yb. As the electrolyte material, _ZrO2 -based oxides, _LaGaO3 -based oxides, _BaZrO3 -based oxides, and _BaCeO3 -based oxides are preferred.

The material for forming the intermediate layer refers to a material that conducts ions such as oxide ions and protons, and has high chemical stability with the electrolyte material and the air electrode material. There are no particular limitations on the material for the intermediate layer, and examples of the material include zirconia-based oxides, ceria-based oxides, and perovskite-type oxides. The material for the intermediate layer may be one type alone or a combination of two or more types.

More specific examples of the material for the intermediate layer include a material made of one or more metals or metal oxides containing one or more selected from the group consisting of Ca, Sc, Sr, Ga, Y, Zr, In, Ba, La, Ce, Pr, Sm, Gd, and Yb. _CeO2 -based oxides are preferred as the material for the intermediate layer.

The material for forming the air electrode refers to a material that conducts electrons or holes and has catalytic activity in the air electrode reaction. There are no particular limitations on the material for forming the air electrode, and examples include perovskite-type oxides. The material for forming the air electrode may be one type alone or a combination of two or more types.

More specific examples of the material for forming the air electrode include a material made of one or more metals or metal oxides including one or more selected from the group consisting of Ca, Sc, Cr, Mn, Fe, Co, Ni, Cu, Sr, Ga, Y, Zr, In, Ba, La, Ce, Pr, Sm, Gd, and Yb. Preferred materials for forming the air electrode include _LaMnO3- based oxides, _LaCoO3 -based oxides, _SmCoO3 -based oxides, and (La, Sr) (Co, Fe) _O3 -based oxides.

The fuel electrode, stacked structure, and solid oxide cell of this embodiment are preferably manufactured by the manufacturing method described below.

As shown in FIG. 1, the fuel electrode of the present invention, i.e., fuel electrode 1, is formed as a laminated structure with electrolyte 4. Electrolyte 4 is generally a dense body to prevent gas leakage.

As shown in FIG. 2, the fuel electrode of the present invention, i.e., fuel electrode 1, is formed as a laminated structure of an electrolyte 4 and a porous support 5. The porous support 5 has a higher porosity than the fuel electrode 1 in order to enhance gas diffusion.

The raw material for the fuel electrode 1 is an oxide powder material. The average particle size of the primary particles when formed into the fuel electrode can be controlled by the particle size, dispersion state, firing temperature, or combination of materials to be composited of this oxide powder material.

When forming the fuel electrode 1, the porosity of the fuel electrode 1 can be controlled by changing the amount of binder, plasticizer, or dispersant added or the firing temperature, or by adding and mixing in a pore-forming agent such as carbon, cellulose, or a polymer.

The manufacturing method of the laminated structure 4 includes, for example, a process of applying a first slurry for producing the fuel electrode 1 onto the porous support 5, then applying a second slurry for producing the electrolyte 4, and then co-firing at a first temperature to form a laminated structure of the porous support 5, the fuel electrode 1, and the electrolyte 4.

The porous support 5 has good electrical conductivity and gas diffusibility. The porosity of the porous support 5 is, for example, 10 to 60% by volume, more preferably 30 to 57%, and particularly preferably 40 to 50%. When the porosity of the porous support is within the above range, good electrical conductivity and gas diffusibility can be maintained. The method for producing the porous support 5 can be, but is not limited to, uniaxial pressure molding, injection molding, extrusion molding, or casting molding. The shape of the porous support 5 can be, but is not limited to, a flat plate shape or a tube shape. Examples of the material for the porous support 5 include oxides such as alumina or zirconia, or heat-resistant metals. The fuel electrode may be a mixture of one or more metal oxides containing at least one of the group consisting of Sc, Sr, Zr, Y, Ba, Ce, Sm, Gd, and Yb, which are ion-conductive materials, and an oxide represented by _MeOα (Me=at least one of Ti, Mn, Fe, Co, Ni, and Cu, 0.8≦α≦2.2), which is an electron-conductive metal oxide.

The preferred range of the mass ratio of the ion conductive material to the oxide represented _{by MeOα} is approximately 30:70 to _70:30 , more preferably 35:65 to _65:35 , and particularly preferably 40:60 to 60:40.

A thin-film dense electrolyte layer is obtained by applying a first slurry, which is the fuel electrode material, onto a porous support 5, then applying a second slurry, which is the electrolyte material, and then co-firing at a first temperature. That is, a laminate is obtained that includes an electrolyte 4, which is a thin-film dense electrolyte layer, an anode 1 formed on one side of the electrolyte 4, and a porous support 5, which is the support for these. The above co-firing makes it possible to shrink the electrolyte together with the porous support 5 and the anode 1, and a dense electrolyte layer with a high relative density is obtained.

Examples of the first slurry application method include screen printing, spray coating, transfer, and dip coating. This coating film is sintered by firing at a first temperature, and the thickness of the fuel electrode 1 obtained after firing is 1.0 μm to 100.0 μm, preferably 1.0 μm to 30.0 μm, and particularly preferably 1.0 μm to 10.0 μm.

Methods for applying the second slurry include screen printing, spray coating, transfer, and dip coating. In any application method, a coating film with high molding density can be obtained by optimizing the particle dispersion of the electrolyte material in the second slurry. Sintering of this coating film progresses by firing at the first temperature, and the film thickness of the electrolyte 4 obtained after firing is 0.1 to 20.0 μm, preferably 0.1 μm to 10.0 μm, and particularly preferably 0.1 μm to 5.0 μm.

To reduce electrical resistance, it is preferable to make the electrolyte 4 as thin as possible. On the other hand, making the electrolyte 4 too thin can cause gas leaks due to defects in the electrolyte 4. Therefore, it is appropriate for the electrolyte 4 to have a thickness of 0.1 μm or more to prevent defects, and a thickness of 20 μm or less to make the electrical resistance of the electrolyte 4 1/2 or less of the total electrical resistance of the solid oxide cell.

The firing temperature of these coating films, i.e., the first temperature, is preferably 1250 to 1500°C, more preferably 1300 to 1450°C, and particularly preferably 1350 to 1400°C. This is because at a firing temperature of 1250°C or higher, sintering of the coating film proceeds sufficiently, and a dense electrolyte is obtained. Also, at a firing temperature of 1500°C or lower, diffusion of elements and volatilization of elements constituting the electrolyte 4 are suppressed. The firing time of the coating film is preferably 1 to 8 hours, more preferably 2 to 6 hours, and particularly preferably 3 to 4 hours.

Figure 3 shows a schematic cross-sectional view of a solid oxide cell according to an embodiment of the present invention. The solid oxide cell according to an embodiment of the present invention comprises the fuel electrode 1 of the present invention, an electrolyte 4, and a porous support 5. In addition, an intermediate layer 6 as an intermediate layer for preventing a reaction, and an air electrode 7 are provided on the electrolyte 4.

The method for manufacturing a solid oxide cell of this embodiment includes, for example, a step of applying a first slurry to a porous support 5, then applying a second slurry, and then co-firing at a first temperature to form a fuel electrode 1 and an electrolyte 4, a step of applying a third slurry to the electrolyte 4, then firing at a second temperature to form an intermediate layer 5, and a step of applying a fourth slurry to the intermediate layer 5, then firing at a third temperature to form an air electrode 7. In addition, when the intermediate layer 5 is not used, for example, a step of applying a first slurry to a porous support 5, then applying a second slurry, and then co-firing at a first temperature to form a fuel electrode 1 and an electrolyte 4, and a step of applying a fourth slurry to the electrolyte 4, then firing at a third temperature to form an air electrode 7.

The porosity, material, and mixture mass ratio of the porous support 5 are the same as those described in the method for manufacturing the fuel electrode. The method for applying the first slurry and the thickness of the fuel electrode 1 are the same as those in the method for manufacturing the fuel electrode. The method for applying the second slurry and the thickness of the electrolyte 4 are the same as those in the method for manufacturing the fuel electrode. The preferred range of the first temperature, which is the co-firing temperature of the fuel electrode 1 and the electrolyte 4, and the reason for that are the same as those in the preferred range of the firing temperature of the coating film, which is the material of the fuel electrode 1 and the electrolyte 4, and the reason for that are the same as those in the method for manufacturing the fuel electrode. The preferred range of the co-firing time and the reason for that are the same as those in the preferred range of the firing time of the coating film, which is the material of the fuel electrode 1 and the electrolyte 4, and the reason for that are the same as those in the method for manufacturing the fuel electrode.

The intermediate layer 6 can be either dense or porous, but it is desirable for the relative density to be high in order to enhance the reaction prevention function. Specifically, 60 to 100% is preferable, 70 to 100% is more preferable, and 80 to 100% is particularly preferable. Furthermore, if the chemical stability of the electrolyte 4 and the air electrode 7 is high (if the reaction prevention function is not necessary), a solid oxide cell can be formed without the intermediate layer 6.

Methods for applying the third slurry include screen printing, spray coating, transfer, and dip coating. In any application method, a coating film with high molding density can be obtained by optimizing the particle dispersion of the intermediate layer material in the third slurry. Sintering of this coating film progresses when it is fired at the second temperature, and the thickness of the intermediate layer 6 obtained after firing is preferably 0.1 to 10 μm.

To reduce electrical resistance, it is preferable to make the intermediate layer 6 as thin as possible. On the other hand, making the thickness too thin impairs the reaction prevention function of the intermediate layer 6. Therefore, it is appropriate for the intermediate layer 6 to have a thickness of 0.1 μm or more to maintain the reaction prevention function, and a thickness of 10 μm or less to make the electrical resistance of the intermediate layer 5 1/2 or less of the total electrical resistance of the solid oxide cell.

The firing temperature of this coating film, i.e., the third temperature, is preferably 1000 to 1400°C, more preferably 1100 to 1350°C, and particularly preferably 1150 to 1300°C. This is because a good sintered state is obtained and the effects of mutual diffusion of elements with the electrolyte 4 are suppressed. The firing time of the coating film is preferably 0.5 to 4 hours, more preferably 1 to 3 hours, and particularly preferably 1 to 2 hours.

Examples of the method for applying the fourth slurry include screen printing, spray coating, transfer, and dip coating. This applied film is sintered by firing at the third temperature, and the thickness of the air electrode 7 obtained after firing is preferably 1 to 100 μm.

In the process of forming the air electrode 7, for example, the air electrode 7 is formed on the electrolyte 4 or the intermediate layer 6. The air electrode 7 preferably contains a perovskite-type oxide material as an electronically conductive material.

The air electrode 7 is a material in which an electronically conductive material and an ionically conductive material are mixed or composited. The third temperature, which is the firing temperature of the air electrode 7, is preferably 700 to 1200°C, more preferably 800 to 1100°C, and particularly preferably 850 to 1050°C. The firing time is preferably 0.5 to 8 hours, more preferably 1 to 6 hours, and particularly preferably 1 to 3 hours.

A solid oxide cell is a device in which a fuel electrode 1, an electrolyte 4, an intermediate layer 6 if necessary, an air electrode 7, and a porous electrode if necessary are formed on a porous support 5 as a support.

Next, the present invention will be explained in more detail with reference to examples, but these are merely illustrative and do not limit the present invention.

Fuel electrodes with different ratios of electronically conductive material to ionically conductive material were fabricated according to the following procedure. Here, the oxide powder material used as the raw material for the fuel electrodes was fabricated by spray pyrolysis.

<Synthesis of oxide powder materials by spray pyrolysis method>
The spray pyrolysis method is one of the techniques for synthesizing nano-sized oxide powder materials. It is possible to synthesize a single oxide powder material, but it is also possible to synthesize an oxide powder material in which two or more types of oxides are combined. In this case, a good dispersion state can be obtained for the two or more types of oxides that are combined. Another feature is that the primary particle size can be controlled over a wide range. The synthesis of oxide powder materials by the spray pyrolysis method in the examples is described below.

The spray pyrolysis process involves preparing an aqueous solution for spraying that contains a metal salt of an electronically conductive material source for the fuel electrode and a metal salt of an ionically conductive material source, atomizing the aqueous solution for spraying by ultrasonic vibration, and then introducing the atomized aqueous solution for spraying into a heating furnace to obtain an oxide powder material for the air electrode.

By appropriately selecting the concentration ratio of each metal element contained in the aqueous solution to be sprayed, the composition ratio of the various metal elements constituting the primary particles of the electronically conductive material and the primary particles of the ionically conductive material for the fuel electrode was adjusted.

The aqueous solution to be sprayed in the spraying device was atomized by ultrasonic vibration (frequency: 1.75 MHz), and then the aqueous solution to be sprayed, which had been atomized by flowing with carrier gas air, was introduced into a heating furnace through a pipe connected to the spraying device. The metal salt of the source of the electronic conductive material for the fuel electrode and the metal salt of the source of the ion conductive material in the aqueous solution to be sprayed were thermally decomposed and oxidized to obtain an oxide powder material for the fuel electrode. A four-stage electric furnace was used as the heating furnace, with the temperatures in each stage being 300, 500, 700, and 900°C from the previous stage, and the heating times in each stage (time to pass through the furnace for each stage) being 8 seconds, 8 seconds, 8 seconds, and 8 seconds from the previous stage).

<Preparation of aqueous solution for spraying>
(1) Aqueous solution for spraying s1
18.542 g of nickel nitrate hexahydrate, 8.910 g of zirconyl nitrate dihydrate, and 2.221 g of yttrium nitrate hexahydrate were weighed and dissolved in pure water, and then pure water was further added so that the amount of the aqueous solution became 1000 ml to prepare an aqueous solution s1 for spraying. By spraying and pyrolyzing the aqueous solution s1 for spraying, 0.1 mol per liter of 50% by mass NiO-50% _by mass ( _ZrO2 ) _0.92 ( _Y2O3 ) _0.08 (hereinafter referred to as YSZ) can be synthesized.
(2) Aqueous solution for spraying s2
21.089 g of nickel nitrate hexahydrate, 6.756 g of zirconyl nitrate dihydrate, and 1.684 g of yttrium nitrate hexahydrate were weighed and dissolved in pure water, and then pure water was further added so that the amount of the aqueous solution became 1000 ml to prepare an aqueous solution s2 for spraying. By spraying and pyrolyzing the aqueous solution s1 for spraying, 0.1 mol of 60 mass% NiO-40 mass% YSZ can be synthesized per 1 L.
(3) Aqueous solution for spraying s3
23.384 g of nickel nitrate hexahydrate, 4.816 g of zirconyl nitrate dihydrate, and 1.200 g of yttrium nitrate hexahydrate were weighed and dissolved in pure water, and then pure water was further added so that the amount of the aqueous solution became 1000 ml to prepare an aqueous solution s3 for spraying. By spraying and pyrolyzing the aqueous solution s1 for spraying, 0.1 mol of 70 mass% NiO-30 mass% YSZ per 1 L can be synthesized.
(4) Aqueous solution for spraying s4
14.72 g of samarium nitrate hexahydrate, 4.63 g of strontium nitrate, 12.73 g of cobalt nitrate hexahydrate, and 19.54 g of cerium nitrate hexahydrate were weighed out, and the rest was prepared in the same manner as in the case of the spray aqueous solution s1. By spraying and pyrolyzing the spray aqueous solution s4, 0.1 mol of 50 mass% SSC-50 mass% SDC per 1 L can be synthesized. The spray aqueous solution s4 is used to manufacture an air electrode.

<Preparation of oxide powder materials>
(1) Oxide powder material p1
The sprayed aqueous solution s1 was used to carry out spray pyrolysis by ultrasonic spray pyrolysis to obtain an oxide powder material p1 of NiO-YSZ.
(2) Oxide powder material p2
Using the sprayed aqueous solution s2, an oxide powder material p2 of NiO-YSZ was obtained in the same manner as in the case of the oxide powder material p1.
(3) Oxide powder material p3
Using the sprayed aqueous solution s3, an oxide powder material p3 of NiO-YSZ was obtained in the same manner as in the case of the oxide powder material p1.
(4) Oxide powder material p4
Using the sprayed aqueous solution s4, an SSC-SDC oxide powder material p4 was obtained in the same manner as in the case of the oxide powder material p1.

<X-ray diffraction analysis of oxide powder materials>
When the three NiO-YSZ oxide powder materials p1 to p3 were subjected to X-ray diffraction analysis (SmartLab, manufactured by Rigaku), diffraction peaks identifiable as NiO and YSZ were observed in all of the NiO-YSZ oxide powder materials, and it was confirmed that they were powder materials containing crystalline NiO and YSZ. Furthermore, when the SSC-SDC oxide powder material p4 was subjected to X-ray diffraction analysis, diffraction peaks identifiable as SSC and SDC were observed, and it was confirmed that they were powder materials containing crystalline SSC and SDC.

<Particle size distribution measurement of oxide powder materials>
The particle size distribution of the oxide powder materials p1 to p4 was measured by a laser diffraction particle size distribution measurement method (Microtrac HRA9320-X100, manufactured by Nikkiso Co., Ltd.) to determine the values of the 10% particle size (D10) based on volume, the 50% particle size (D50) based on volume, and the 90% particle size (D90) based on volume. Note that the oxide powder material is an aggregate secondary particle in which finer primary particles are compounded, and the particle size distribution measured here is the value for the aggregate secondary particle. The results are shown below.
<Oxide powder material p1>
D10: 0.49 μm, D50: 0.65 μm, D90: 0.93 μm
<Oxide powder material p2>
D10: 0.47 μm, D50: 0.63 μm, D90: 0.94 μm
<Oxide powder material p3>
D10: 0.49 μm, D50: 0.67 μm, D90: 1.00 μm
<Oxide powder material p4>
D10: 0.62 μm, D50: 0.91 μm, D90: 1.26 μm

<Measurement of the average particle size of primary particles of oxide powder material>
The average particle size of the primary particles of the oxide powder materials p1 to p4 was determined by the peak half-width of X-ray diffraction (SmartLab, manufactured by Rigaku) and Scherrer's formula (Scherrer constant: 0.9). As a result, the primary particles of NiO, YSZ, SSC, and SDC synthesized as primary particles were all about 15 nm.

<Preparation of Porous Support>
NiO (Sumitomo Metal Mining Co., Ltd.) and YSZ (TZ-8YS, Tosoh Corporation) were mixed in a mass ratio of 6:4, and a cellulose-based binder, a pore former, and water were added to the mixed powder and mixed. The pore former was a mixture of carbon and cellulose in a ratio of 2:1, and was added in an amount of 25 mass% based on the sum of the masses of NiO and YSZ.

The mixture was extrusion molded into a flat green sheet with a width of 120 mm and a thickness of 0.7 mm. The green sheet was then cut into pieces with a diameter of 32 mm using a punch, and then fired at 1240°C for 2 hours in an air atmosphere to obtain a calcined porous support body.

<Preparation of slurry for fuel electrode>
(1) Anode slurry S1
The oxide powder material p1 was mixed with ethyl cellulose, a plasticizer, a dispersant, and α-terpineol, and the mixture was kneaded in a kneader at room temperature for 1 minute and 30 seconds to obtain a slurry S1 for the anode.
(2) Anode slurry S2
The oxide powder material p2 was mixed with ethyl cellulose, a plasticizer, a dispersant, and α-terpineol, and the mixture was kneaded in a kneader at room temperature for 1 minute and 30 seconds to obtain a slurry S2 for the anode.
(3) Anode slurry S3
The oxide powder material p3 was mixed with ethyl cellulose, a plasticizer, a dispersant, and α-terpineol, and the mixture was kneaded in a kneader at room temperature for 1 minute and 30 seconds to obtain a slurry S3 for the fuel electrode.

<Preparation of electrolyte slurry>
YSZ powder (TZ-8Y, manufactured by Tosoh Corporation) was mixed with ethyl cellulose, a plasticizer, a dispersant, and α-terpineol, and the mixture was kneaded in a kneader at room temperature for 1 minute and 30 seconds to obtain a slurry for the electrolyte.

<Preparation of intermediate layer slurry>
Ce _0.9 Gd _0.1 O _1.95 powder (CGO90/10, UHSA, manufactured by Solvay Specialchem Japan) was mixed with ethyl cellulose, a plasticizer, a dispersant, and α-terpineol, and the mixture was kneaded in a kneader at room temperature for 1 minute and 30 seconds to obtain a slurry for the intermediate layer.

<Preparation of slurry for air electrode>
The oxide powder material p4 was mixed with ethyl cellulose, a plasticizer, a dispersant, and α-terpineol, and the mixture was kneaded in a kneader at room temperature for 1 minute and 30 seconds to obtain a slurry for the air electrode.

<Preparation of a solid oxide cell as an example>
(1) Example 1
The slurry for the fuel electrode S1 was applied to the calcined porous support body by screen printing, and then the slurry for the electrolyte was applied to the slurry for the fuel electrode S1 applied to the calcined porous support body by screen printing, and then fired at 1360°C for 3 hours in an air atmosphere to obtain a laminated structure of an electrolyte, a fuel electrode, and a porous support. Then, the slurry for the intermediate layer was applied to the electrolyte of the laminated structure by screen printing, and then fired at 1300°C for 1 hour in an air atmosphere to obtain an intermediate layer. Then, the slurry for the air electrode was applied to the intermediate layer by screen printing, and then fired at 900°C for 1 hour in an air atmosphere to obtain an air electrode. In this manner, the solid oxide cell of Example 1 was produced.

(2) Example 2
The slurry for the fuel electrode S2 was applied to the calcined porous support body by screen printing, and then the slurry for the electrolyte was applied to the slurry for the fuel electrode S2 applied to the calcined porous support body by screen printing, and then fired at 1360°C for 3 hours in an air atmosphere to obtain a laminated structure of an electrolyte, a fuel electrode, and a porous support. Then, the slurry for the intermediate layer was applied to the electrolyte of the laminated structure by screen printing, and then fired at 1300°C for 1 hour in an air atmosphere to obtain an intermediate layer. Then, the slurry for the air electrode was applied to the intermediate layer by screen printing, and then fired at 900°C for 1 hour in an air atmosphere to obtain an air electrode. In this manner, the solid oxide cell of Example 2 was produced.

(3) Example 3
The slurry for the fuel electrode S3 was applied to the calcined porous support body by screen printing, and then the slurry for the electrolyte was applied to the slurry for the fuel electrode S3 applied to the calcined porous support body by screen printing, and then fired at 1360°C for 3 hours in an air atmosphere to obtain a laminated structure of an electrolyte, a fuel electrode, and a porous support. Then, the slurry for the intermediate layer was applied to the electrolyte of the laminated structure by screen printing, and then fired at 1300°C for 1 hour in an air atmosphere to obtain an intermediate layer. Then, the slurry for the air electrode was applied to the intermediate layer by screen printing, and then fired at 900°C for 1 hour in an air atmosphere to obtain an air electrode. In this manner, the solid oxide cell of Example 3 was produced.

In the solid oxide cells of Examples 1 to 3, the thickness of each member is about 0.55 mm for the porous support, about 5.0 μm for the fuel electrode, about 3.0 μm for the electrolyte, about 2.0 μm for the intermediate layer, and about 30.0 μm for the air electrode. The thickness of the fuel electrode was 4.0 μm at the thinnest point and 6.0 μm at the thickest point in Example 1, 4.0 μm at the thinnest point and 6.0 μm at the thickest point in Example 2, and 4.0 μm at the thinnest point and 6.0 μm at the thickest point in Example 3. The thickness of the electrolyte was 2.5 μm at the thinnest point and 3.5 μm at the thickest point in Example 1, 2.5 μm at the thinnest point and 3.5 μm at the thickest point in Example 2, and 2.5 μm at the thinnest point and 3.5 μm at the thickest point in Example 3.

<Preparation of a solid oxide cell as a comparative example>
(1) Comparative Example 1
The electrolyte slurry was applied to the calcined porous support body by screen printing, and then fired at 1360°C for 3 hours in an air atmosphere to obtain a laminated structure of the electrolyte and the porous support. Then, the intermediate layer slurry was applied to the electrolyte of the laminated structure by screen printing, and then fired at 1300°C for 1 hour in an air atmosphere to obtain an intermediate layer. Then, the air electrode slurry was applied to the intermediate layer by screen printing, and then fired at 900°C for 1 hour in an air atmosphere to obtain an air electrode. In this manner, the solid oxide cell of Comparative Example 1 was produced. In Comparative Example 1, since the material of the porous support is NiO-YSZ, the porous support functions as a support and at the same time as a fuel electrode of the solid oxide cell in the electrochemical reaction.

The thickness of each component in the solid oxide cell of Comparative Example 1 is approximately 0.55 mm for the porous support, approximately 3.0 μm for the electrolyte, approximately 2.0 μm for the intermediate layer, and approximately 30.0 μm for the air electrode. In the comparative example, the porous support also serves as the fuel electrode. The electrolyte film thickness was 2.5 μm at its thinnest point and 3.5 μm at its thickest point.

<Performance evaluation of solid oxide cells>
For the solid oxide cells of Examples 1 to 3 and Comparative Example 1, power generation characteristics and AC impedance were measured using a potentiostat/frequency analyzer (Autolab PGSTAT302, manufactured by Metrohm). Air was introduced to the air electrode side of the solid oxide cell, and 3% humidified hydrogen was introduced to the fuel electrode side, and measurements were performed at 700°C. As a measurement example, the results of the power generation characteristics and AC impedance measurements (Cole-Cole plots) in Example 2 are shown in Figures 5 and 6, respectively. The results of the power generation characteristics measurements (maximum power density) and the AC impedance measurements (electrode resistance) for the solid oxide cells of Examples 1 to 3 and Comparative Example 1 are shown in Table 1. The electrode resistance of a cell is the difference between the real resistance values of two intercepts on the horizontal axis of a graph obtained by plotting the real resistance value Z' (Ω) and the imaginary resistance value Z" (Ω) for each frequency when the frequency is changed, the real resistance value Z' being plotted on the horizontal axis and the imaginary resistance value Z" being plotted on the vertical axis, the Cole-Cole plot of the cell being measured obtained by the AC impedance method.

<Cross-section processing for fuel electrode observation>
In order to observe the fuel electrode after the performance evaluation of the solid oxide cell, the cell cross sections of Examples 1 to 3 and Comparative Example 1 were smoothed with a cross-section polisher (Ar ion beam, IB-19510CP, manufactured by JEOL Ltd.). Since the performance evaluation of the solid oxide cell had been performed, NiO in the fuel electrode and the porous support was reduced to Ni.

<Observation of the fuel electrode>
After the above cross-section processing, the anode was observed with an LV-SEM (Ultra55, manufactured by Carl Zeiss) and the image is shown in FIG. 7. The porosity of each anode was measured from the contrast of each LV-SEM image by image processing using image analysis software (WinROOF2018, manufactured by Mitani Shoji). In addition, the particle size of the observed Ni particles and YSZ particles was measured on the image using the same image analysis software, and the average particle size and its standard deviation of each material were calculated. These results are shown in Table 2.

As shown in Table 1, Examples 1 to 3 showed a high maximum power density and low electrode resistance compared to Comparative Example 1. This is because the fuel electrode material contains an electronically conductive material and an ionically conductive material in a specific range of mass ratios, and the average particle size, particle size distribution, film thickness, and porosity of each of the electronically conductive material and the ionically conductive material are set within specific ranges, thereby dramatically reducing the electrode resistance of the fuel electrode and, as a result, realizing a high maximum power density.

The porous supports in Examples 1 to 3 are made of the same material as in Comparative Example 1, so the measurement results for Comparative Example 1 shown in Table 2 correspond to the physical property values (porosity, average particle size, and standard deviation of particle size distribution) of the porous supports in Examples 1 to 3.

<Cross-section processing for electrolyte observation>
In order to observe the electrolyte after the performance evaluation of the solid oxide cells, the cell cross sections of Examples 1 to 3 and Comparative Example 1 were smoothed with a cross-section polisher (Ar ion beam, IB-19510CP, manufactured by JEOL Ltd.).

<Observation of electrolyte>
FIG. 8 shows an image of Example 2 in which the electrolyte was observed with an LV-SEM (Ultra55, manufactured by Carl Zeiss) after the above-mentioned cross-section treatment. The relative density of the electrolyte was measured from the contrast of the LV-SEM image by image processing using image analysis software (WinROOF2018, manufactured by Mitani Shoji). As a result, the relative density of Example 2 was 99%. The relative densities of the electrolytes of Examples 1 and 3 and Comparative Example 1, which were measured in the same manner, were also 99%.

By using this invention, it is possible to manufacture a solid oxide cell fuel electrode and a solid oxide cell that have excellent performance and low electrode resistance of the fuel electrode.

Claims (9)

1. A fuel electrode for a solid oxide cell, comprising:
The present invention is made of a sintered body of a raw material containing an electronic conductive material and an ion conductive material,
The average particle size of the electron conductive material is 0.001 to 2.00 μm, and the average particle size of the ion conductive material is 0.001 to 2.00 μm;
When the standard deviation of the particle size distribution of the electron conductive material is A ₁ (μm) and the average particle size of the electron conductive material is B ₁ (μm), the value of (A ₁ /B ₁ )×100 is 0.000 to 20.0,
the standard deviation of the particle size distribution of the ion-conductive material is A ₂ (μm) and the average particle size of the ion-conductive material is B ₂ (μm), the value of (A ₂ /B ₂ )×100 is 0.000 to 20.0;
A fuel electrode for a solid oxide cell, comprising: The fuel electrode for a solid oxide cell according to claim 1, characterized in that the film thickness is 1.0 μm to 100.0 μm and the porosity is 15 to 40 vol %. the electron conductive material is at least one metal or metal oxide including at least one selected from the group consisting of Ni, Cu, Fe, Co, Mn, Cr, La, Sm, Gd, Ce, Pr, Sr, Ca, and Ba;
the ion conductive material is at least one metal oxide containing at least one selected from the group consisting of Sc, Sr, Zr, Y, Ba, Ce, Sm, Gd, and Yb;
the mass ratio of the electronic conductive material to the ion conductive material (mass of the electronic conductive material:mass of the ion conductive material) is 80:20 to 40:60;
2. The solid oxide cell fuel electrode according to claim 1, a solid oxide cell fuel electrode according to any one of claims 1 to 3 laminated with the electrolyte;
The electrolyte has a film thickness of 0.1 to 20.0 μm, and is a dense body having a relative density of 95 to 100%;
A laminated structure comprising: A porous support and a solid oxide cell fuel electrode according to any one of claims 1 to 3 laminated on the porous support,
the porosity of the porous support is higher than the porosity of the solid oxide cell anode;
A laminated structure comprising: A solid oxide cell having a solid oxide cell fuel electrode according to any one of claims 1 to 3. A solid oxide cell having the laminated structure according to claim 4 or 5. 6. A method for producing a laminated structure according to claim 4 or 5 , further comprising the steps of: applying a first slurry for producing an anode for a solid oxide cell onto a porous support; then applying a second slurry for producing an electrolyte onto the porous support; and then firing the resulting mixture at a first temperature to form a porous support, an anode , and an electrolyte. A step of applying a first slurry for preparing an anode for a solid oxide cell onto a porous support, then applying a second slurry for preparing an electrolyte onto the porous support, and then firing at a first temperature to form a porous support, an anode, and an electrolyte;
applying a third slurry for forming an intermediate layer on the formed electrolyte, and then firing the third slurry at a second temperature to form the intermediate layer;
applying a fourth slurry for producing an air electrode onto the formed intermediate layer, and then firing the resulting mixture at a third temperature to form an air electrode;
8. The method for producing a solid oxide cell according to claim 6, further comprising the steps of: