JP2003277058A - Zirconia material forming solid solution with scandia and solid oxide type fuel cell provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zirconia material forming a solid solution with scandia which has excellent sintering property and suitable for an electrolyte film of a solid oxide type fuel cell. <P>SOLUTION: The zirconia material forming the solid solution with scandia has 5-20 m<SP>2</SP>g<SP>-1</SP>BET value and 0.1-2.0 μm particle size distribution. It is further preferable that the zirconia material forming the solid solution with scandia has 0.3-1.0 μm average particle diameter. The quantity of scandia forming the solid solution is preferably 3-12 mol%. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a zirconia (hereinafter referred to as SSZ) material in which scandia is dissolved.
In particular, it relates to an SSZ material having excellent sinterability and suitable for an electrolyte membrane of a solid oxide fuel cell.

[0002]

2. Description of the Related Art Conventionally, Japanese Patent Laid-Open No. 8-31432 proposes to use an SSZ material having a solid solution amount of scandia of 8 to 15 mol% for an electrolyte membrane of a solid oxide fuel cell.

In Japanese Patent Laid-Open No. 7-73891, an SSZ material is produced by a sol-gel method or a coprecipitation method, then heat-treated and ground to obtain an average particle diameter of
It has been proposed to use a material having a thickness of 2 to 3 μm for an electrolyte membrane of a solid oxide fuel cell.

Conventionally, in Japanese Patent Laid-Open No. 10-158894, a zirconia (hereinafter referred to as YSZ) material containing yttria as a solid solution has been used as an electrolyte membrane of a solid oxide fuel cell.

[Problems to be Solved by the Invention]

The composition of the SSZ material disclosed in JP-A-8-31432 has a high ionic conductivity, and it is expected that the output performance will be improved if it is used in the electrolyte membrane of a solid oxide fuel cell. However, although we prepared an electrolyte membrane of a solid oxide fuel cell using the SSZ material of the above composition, we could not produce an electrolyte membrane without gas permeability, and conversely the output performance was low. It was It was considered that the reason why the electrolyte membrane having no gas permeability could not be produced was that the BET value and particle size distribution of the SSZ material were not appropriate.

An electrolyte membrane for a solid oxide fuel cell was produced from the SSZ material obtained by the method disclosed in JP-A-7-73891, but an electrolyte membrane having no gas permeability could not be produced. It was considered that this was because the average particle size of 2 to 3 μm was too large.

The electrolyte membrane having no gas permeability shown here is provided with a pressure difference between one side and the opposite side of the electrolyte membrane, and is evaluated by the amount of gas permeation that passes through the gap, and the amount of gas permeation Q ≦ 2.8 × 10 ⁻⁹ ms ⁻¹ Pa ⁻¹ (more preferably Q ≦ 2.8 × 10
^-10 ms ^-1 Pa ^-1 ).

As an electrolyte membrane of a solid oxide fuel cell,
When the YSZ material is used, when the power generation temperature is 900 ° C. or lower, the ionic conductivity of the YSZ material is reduced, and thus the output performance is significantly reduced.

An object of the present invention is to provide an SSZ material which has excellent sinterability and is suitable as an electrolyte membrane of a solid oxide fuel cell.

[0010]

Means for Solving the Problems To achieve the above object, the first invention is that the BET value is 5 to ²⁰ m ² g ^-1 and the particle size distribution is
An SSZ material having a range of 0.1 to 2.0 μm is provided.

According to the present invention, since the BET value and the particle size distribution of the SSZ material are limited to the above ranges, it is possible to provide the SSZ material having excellent sinterability, and the material is used as an electrolyte for a solid oxide fuel cell. When used as a membrane, an electrolyte membrane having no gas permeability can be provided.

[0012] The reason is because the BET value 5 m ² g ^-1 smaller than sinterability can not be made gas permeable free electrolyte membrane low, whereas BET value than 20 m ² g ^-1 This is because if it is large, the sinterability is too high and cracks occur in the electrolyte membrane. In addition, the reason why the particle size distribution outside the range of 0.1 to 2.0 μm is bad is
This is because if a material smaller than 0.1 μm is included, the sinterability is too high and cracks occur in the electrolyte membrane.On the other hand, if a material larger than 2.0 μm is included, the sinterability decreases and an electrolyte membrane without gas permeability is produced. This is because what cannot be done and the adhesion between the air electrode and the fuel electrode is deteriorated and peeling may occur.

The BET value shown here is a value obtained by measurement using a flow type specific surface area measuring apparatus Flowsorb II2300 manufactured by Shimadzu Corporation. The particle size distribution is a value obtained by measurement using a laser diffraction particle size distribution analyzer SALD-2000 manufactured by Shimadzu Corporation.

In order to achieve the above object, a second invention is SS
It is provided that the average particle diameter in the Z material is 0.3 to 1.0 μm.

According to the present invention, the average particle size is limited in addition to the BET value and the particle size distribution, so that it is possible to provide an SSZ material having excellent sinterability, which is used for a solid oxide fuel cell. When used as an electrolyte membrane, it is possible to provide an electrolyte membrane having no gas permeability.

The reason for this is that if it is less than 0.3 μm, the sinterability is too high and cracks may occur in the electrolyte membrane, while if it is more than 1.0 μm, the sinterability is lowered and the electrolyte membrane does not have gas permeability. This is because it becomes difficult to fabricate. When the average particle size is in the range of 0.3 to 1.0 μm, the gas permeation amount Q ≦
2.8 × 10 ^-10 ms ^-1 Pa ^-1 electrolyte membrane can be prepared,
This is because it is more preferable.

The average particle diameter shown here is the value of the median diameter (50% diameter) obtained by measurement using a laser diffraction particle size distribution analyzer SALD-2000 manufactured by Shimadzu Corporation.

In order to achieve the above object, a third invention is S
It is provided that the solid solution amount of scandia in the SZ material is 3 to 12 mol%.

According to the present invention, since the solid solution amount of scandia is further limited, the ionic conductivity is high and the sinterability is excellent.
SSZ material can be provided. When the material is used for an electrolyte membrane of a solid oxide fuel cell, an electrolyte membrane having no gas permeability can be produced, and a solid oxide fuel cell having excellent output performance can be provided.

The reason for this is that the amount of scandia dissolved is 3 mol.
If it is less than%, the ionic conductivity will decrease, and the output performance will decrease even if an electrolyte membrane having no gas permeability can be produced.
On the other hand, when the content is more than 12 mol%, the crystal phase precipitates a rhombohedral phase in addition to the cubic crystal, so the ionic conductivity decreases, and the output performance decreases even if an electrolyte membrane without gas permeability can be produced. is there.

In order to achieve the above object, a fourth invention is S
CeO ₂ is further solid-dissolved in the SZ material, and the solid solution amount of the component is
It is provided that it is 0.5 to 5 mol%.

According to the invention, the SSZ material is additionally provided with CeO _2.
Since it is 0.5 to 5 mol% solid solution, it has high ionic conductivity,
It is possible to provide an SSZ material having excellent sinterability. When the material is used for an electrolyte membrane of a solid oxide fuel cell, an electrolyte membrane having no gas permeability can be produced, and a solid oxide fuel cell having excellent output performance can be provided.

[0023] This is because the solid solution amount of CeO ₂ is not a solid solution of CeO ₂ for a small amount of solid solution is less than 0.5 mol% SSZ
Because there is no difference between the material and ionic conductivity, on the other hand, the amount of solid solution is
This is because if it is more than 5 mol%, it has electronic conductivity in a reducing atmosphere, and if it is used as an electrolyte membrane of a solid oxide fuel cell, the output performance is reduced.

In order to achieve the above object, a fifth invention is
The SSZ material is further solid solution Bi ₂ O ₃ and CeO _2, the Bi ₂ O
It is provided that the total solid solution amount of ₃ and CeO ₂ is 0.5 to 5 mol%.

According to the present invention, the SSZ material contains 0.5 to 5 mol% of Bi ₂ O ₃ and CeO _{2 as} a solid solution, so that the SSZ material has high ionic conductivity and excellent sinterability. You can When the material is used for an electrolyte membrane of a solid oxide fuel cell, an electrolyte membrane having no gas permeability can be produced even at a low temperature, so that a solid oxide fuel cell having excellent output performance can be provided.

[0026] Bi ₂ O ₃ reasons be preferable to solid solution is, Bi ₂ O ₃ has a melting point as low as about 820 ° C., and a boiling point of 1900 ° C.
Because of its high temperature, it is not only possible to sinter the SSZ material at low temperature, but also an electrolyte membrane that does not have gas permeability even at the firing temperature (1350 to 1500 ° C) of the air electrode and fuel electrode of the solid oxide fuel cell. This is because it can be easily manufactured.

When the total amount of solid solution is less than 0.5 mol%, the ionic conductivity and sinterability are improved as compared with the SSZ material in which the amount of solid solution is too small to dissolve Bi ₂ O ₃ and CeO ₂ in solid solution. On the other hand, if the solid solution amount is more than 5 mol%, the sinterability becomes too high and cracks occur in the electrolyte membrane, and the solid oxide fuel has electronic conductivity in a reducing atmosphere. This is because when it is used as an electrolyte membrane of a battery, output performance may be reduced.

Note that Bi₂O₃About melting point is about 820 ℃
It is low, but if fired at a high temperature of 1 degree, Bi₂O ₃On the crystal layer of SSZ
Power generation of solid oxide fuel cell because it is solid-solved and stabilized
There is no problem because it does not diffuse at temperature.

In order to achieve the above object, a sixth invention is
The SSZ material is provided by being heat-treated at 800-1000 ° C and crushed.

According to the present invention, the SSZ material excellent in sinterability can be provided because it is heat-treated at 800 to 1000 ° C. and pulverized, and the material can be used as an electrolyte membrane of a solid oxide fuel cell. If used, an electrolyte membrane having no gas permeability can be provided.

The reason for this is that the heat treatment at a temperature lower than 800 ° C. causes a crack in the electrolyte membrane when the material is used for the electrolyte membrane because the particle size of the primary particles is too small. On the other hand, a heat treatment higher than 1000 ° C. This is because the sinterability of SSZ material is too low and the sinterability is not improved even if the particles are further crushed to make the particles finer, and an electrolyte membrane having no gas permeability cannot be produced.

In order to achieve the above object, a seventh invention is:
A cell comprising an electrolyte membrane, a fuel electrode on one surface of the electrolyte membrane, and an air electrode provided on the opposite surface of the electrolyte membrane, and a cell connected to the air electrode or the surface of the fuel electrode and serving as an electrical connection. A solid oxide fuel cell comprising the interconnector having the above, wherein the electrolyte membrane is made of the SSZ material according to any one of the first invention to the sixth invention.

According to the present invention, since the SSZ material according to any one of the first to sixth inventions is used for the electrolyte membrane of the solid oxide fuel cell, the conventional YSZ material is used for the electrolyte membrane. It is possible to provide a solid oxide fuel cell having higher output performance than the solid oxide fuel cell.

The reason for this is that an SSZ material having a higher ionic conductivity than the YSZ material can be used to form an electrolyte membrane having no gas permeability, so that the internal resistance of the electrolyte membrane becomes small.
This is because it is possible to obtain higher output performance than the solid oxide fuel cell in which the YSZ material is used for the electrolyte membrane.

[0035]

DETAILED DESCRIPTION OF THE INVENTION A solid oxide fuel cell will be described as an embodiment of the present invention. FIG. 1 is a view showing a cross section of a cylindrical solid oxide fuel cell. A strip-shaped interconnector 2 and an electrolyte membrane 3 are provided on a cylindrical air electrode support 1, and a fuel electrode membrane 4 is formed on the electrolyte membrane 3 so as not to come into contact with the interconnector 2. When Air is flown inside the air electrode support and fuel is flown outside, oxygen in Air is converted into oxygen ions at the interface between the air electrode and the electrolyte membrane, and these oxygen ions reach the fuel electrode through the electrolyte. Then, the fuel gas and oxygen ions react to form water and carbon dioxide. These reactions are shown by the equations (1) and (2). Electricity can be taken out by connecting the fuel electrode 4 and the interconnector 2. ^{_{H 2 + O 2- → H 2}} O + 2e - ... (1) CO + O 2- → CO 2 + 2e - ... (2)

FIG. 2 is a cross section showing a type in which an air side electrode reaction layer 1a is provided between the air electrode 1 and the electrolyte membrane 3 and a fuel side electrode reaction layer 4a is provided between the electrolyte membrane 3 and the fuel electrode 4. It is a figure. The air side electrode reaction layer 1a is a layer provided in order to efficiently perform the reaction of formula (3) in which oxygen ions are generated from oxygen gas and electrons from the air electrode.
Oxygen ions generated in 1a move to the fuel electrode side through the electrolyte membrane 3. Then, the reactions shown in the equations (1) and (2) are performed in the fuel side electrode reaction layer 4a, and the fuel electrode 4 and the interconnector 2
Electricity can be taken out by connecting with.
Therefore, the air-side electrode reaction layer, the electrolyte membrane, and the fuel-side electrode reaction layer are important in order to obtain high output performance especially at a low temperature of about 700 to 900 ° C. ^{_{1 / 2O 2 + 2e - →}} O 2- ... (3)

The electrolyte membrane in the present invention is required to have high oxygen ion conductivity, no gas permeability, and no electronic conductivity in the air atmosphere and the fuel atmosphere at the power generation temperature of the solid oxide fuel cell. To be done. From this viewpoint, an electrolyte membrane made of SSZ material is preferable.

Since the SSZ material has low sinterability as compared with the conventionally used YSZ material, the BET value, particle size distribution and average particle diameter of the SSZ material are required to prepare an electrolyte membrane having no gas permeability. It has to be more appropriate. From this viewpoint, the BET value is 5 to ²⁰ m ² g ^-1 , and the particle size distribution is 0.1 to 2.0 μm.
Is preferred. Further, when the average particle diameter is limited to 0.3 to 1.0 μm, an electrolyte membrane having a gas permeation amount Q ≦ 2.8 × 10 ⁻¹⁰ ms ⁻¹ Pa ⁻¹ can be produced, which is more preferable.

In the SSZ material, the solid solution amount of scandia is preferably 3 to 12 mol% from the viewpoint of high oxygen ion conductivity and no electronic conductivity, and 8 to 12 mol% from the viewpoint of high oxygen ion conductivity. Is more preferable.

In the present invention, it is preferable that 0.5 to 5 mol% of CeO ₂ be solid-dissolved in order to improve the oxygen ion conductivity of the SSZ material. However, in addition to CeO ₂ , atomic number 39
And a rare earth oxide of 57 to 71 may be solid-dissolved. As a solid solution method, Sm ₂ O ₃ , Gd ₂ O ₃ or the like may be solid solution alone, or Sm ₂ O ₃ may be solid solution in the form of CeO _2. Furthermore, ₂ of Sm ₂ O ₃ and Gd ₂ O ₃
It may be a solid solution of a plurality of oxides such as a solid solution of various kinds. All of the above examples can improve the oxygen ion conductivity, and are therefore preferable as the electrolyte membrane material of the solid oxide fuel cell.

The SSZ material in the present invention may contain a sintering aid in order to improve the sinterability.
As a sintering aid, Bi ₂ O ₃ can be dissolved in solid solution, Al ₂ O ₃ , SiO ₂
Etc. may be added.

The SSZ material in the present invention is preferably heat-treated at 800 to 1000 ° C. and pulverized. As a pulverization method at this time, the BET value is 5 to ²⁰ m ² g ⁻¹ and the particle size is There is no particular limitation as long as the distribution is 0.1 to 2.0 μm.
Examples thereof include bead milling, ball milling, and planetary milling. Milling with a bead mill is preferable from the viewpoint that it can be produced in a short time.

The method for synthesizing the starting material for the SSZ material in the present invention is not particularly limited as long as it is a method in which scandia is uniformly dissolved. The coprecipitation method and the like can be mentioned.

The role of the fuel-side electrode reaction layer in the present invention is to function under the fuel atmosphere at the power generation temperature of the solid oxide fuel cell.
It is to carry out the reaction of the equations (1) and (2) efficiently. For this purpose, the fuel-side electrode reaction layer has a high oxygen ion conductivity, a high gas permeability of hydrogen and carbon monoxide gas, an electron conductivity, and a thermal expansion coefficient of SSZ material value. It is required to be close. As a material that satisfies these required characteristics, a layer in which NiO and SSZ are uniformly mixed (hereinafter, N
iO / SSZ), a layer in which NiO and YSZ are uniformly mixed (hereinafter,
NiO / YSZ) and a layer in which NiO and cerium oxide are uniformly mixed (hereinafter referred to as NiO / cerium oxide) are preferable. NiO is reduced to Ni under the operating atmosphere of a solid oxide fuel cell, and the layers are Ni / SSZ, Ni / YSZ and Ni /
Becomes cerium oxide.

In the fuel-side electrode reaction layer, since it has oxygen ion conductivity and electron conductivity, the ratio of NiO is 10-5.
It is preferably 0 part by weight. Further, the structure may be such that the ratio of NiO is inclined from the electrolyte membrane toward the fuel electrode side such as 10, 30 and 50 parts by weight. From the viewpoint of reducing the difference in thermal expansion between the electrolyte membrane and the fuel electrode, it is preferable to incline.

The cerium oxide may contain Sm, Gd, Y and the like, and from the viewpoint of high oxygen ion conductivity, (CeO ₂ ) _1-X (A ₂ O ₃ ) _X (where A = Any one of Sm, Gd, Y,
The one represented by 0.05 ≦ X ≦ 0.15) is more preferable.

The fuel electrode of the present invention has a high electron conductivity, a high fuel gas permeability, an excellent durability, and a thermal expansion coefficient of SSZ material in a fuel gas atmosphere at the power generation temperature of a solid oxide fuel cell. It is required to be close to the value of. From this viewpoint, a layer (hereinafter referred to as NiO / CSZ) in which NiO / YSZ, NiO / SSZ, NiO / cerium oxide, and zirconia in which NiO and Ca are solid-dissolved is uniformly mixed is preferable. NiO is reduced to Ni under the operating atmosphere of the solid oxide fuel cell, and the layers become Ni / YSZ, Ni / SSZ, Ni / cerium oxide and Ni / CSZ.

The roles of YSZ, SSZ, cerium oxide and CSZ in the fuel electrode are stable as long as they are stable in the fuel gas atmosphere of the solid oxide fuel cell and can suppress Ni agglomeration. If it is performance, it is preferable that the cost is low. From this viewpoint, YSZ and CSZ are preferable.

From the viewpoint of high electronic conductivity, the weight ratio of NiO in the fuel electrode is preferably 50 to 90 parts by weight, and from the viewpoint of high gas permeability, the average particle size of the raw material powder used for the fuel electrode is high. The diameter is preferably 0.5 to 10 μm. The reason for this is that if the weight ratio of NiO is less than 50 parts by weight, the electronic conductivity of the fuel electrode becomes low, and if it is more than 90 parts by weight, Ni reduced in the operating atmosphere of the solid oxide fuel cell aggregates. Therefore, the durability is reduced. On the other hand, if the fuel electrode is made from a raw material powder smaller than 0.5 μm, a fuel electrode with high gas permeability cannot be made.On the other hand, if the fuel electrode is made from a raw material powder larger than 10 μm, the porosity of the fuel electrode becomes too large. This is because a fuel electrode having high electronic conductivity cannot be obtained.

The role of the air-side electrode reaction layer in the present invention is to function under the air atmosphere at the power generation temperature of the solid oxide fuel cell.
Efficiently performing the reaction of formula (3). For this purpose, it is required that the air-side electrode reaction layer has high oxygen ion conductivity, high oxygen gas permeability, electron conductivity, and a thermal expansion coefficient close to that of the SSZ material. . As a material that meets these required characteristics, Ca or Sr
Is a solid solution of lanthanum Manganite and SSZ are uniformly mixed (hereinafter referred to as LaBMnO ₃ / SSZ (where B = Ca or Sr)), and lanthanum in which Ca or Sr is dissolved. A layer in which manganite and YSZ are uniformly mixed (referred to as LaBMnO ₃ / YSZ), and a layer in which lanthanum manganite in which Ca or Sr is dissolved as a solid solution and cerium oxide are uniformly mixed (hereinafter referred to as LaBMn
Indicated as O ₃ / cerium oxide. ) And the like.

Also, in the air side electrode reaction layer, Ca or
Lanthanum manganite in which Sr is dissolved is Ce, Sm, for improving electronic conductivity and oxygen ion conductivity.
It may be a solid solution of Pr, Nd, Co, Fe, Ni or the like.

The cerium oxide may contain Sm, Gd, Y and the like, and from the viewpoint of high oxygen ion conductivity, (CeO ₂ ) _1-X (A ₂ O ₃ ) _X (where A = Any one of Sm, Gd, Y,
The one represented by 0.05 ≦ X ≦ 0.15) is more preferable.

The air electrode of the present invention is required to have high electronic conductivity, high oxygen gas permeability, and thermal expansion coefficient close to that of the SSZ material in the air atmosphere of the solid oxide fuel cell. From this viewpoint, a layer made of lanthanum manganite in which Ca or Sr is dissolved is preferable.

The air electrode comprising the lanthanum manganite layer in which Ca or Sr is solid-solved in the present invention contains Ce, Sm, Gd, Pr, Nd, Co, Fe, Ni, etc. for reasons such as improvement of electronic conductivity. It may be a solid solution.

The interconnector of the present invention has high electronic conductivity in the air atmosphere and fuel atmosphere of the solid oxide fuel cell, no gas permeability, no oxygen ion conductivity, and a thermal expansion coefficient of SSZ material. It is required to be close to the value of. From this viewpoint, lanthanum chromite is most preferable.

Since lanthanum chromite is difficult to sinter, it is difficult to manufacture an interconnector having no gas permeability at the firing temperature (1500 ° C. or lower) of a solid oxide fuel cell. In order to improve the sinterability, it is preferable to use Ca, Sr, and Mg as a solid solution. A solid solution of Ca is most preferable because it has the highest sinterability and can form a membrane having no gas permeability at a temperature similar to that of other materials of the solid oxide fuel cell.

There is no particular limitation on the amount of lanthanum chromite in which Ca is used as a solid solution for the interconnector. The higher the solid solution amount of Ca, the higher the electronic conductivity, but
Lanthanum chromite 10 due to reduced material stability
About 10 to 40 mol% is preferable with respect to 0 mol%.

The shape of the solid oxide fuel cell in the present invention is not particularly limited, and may be a flat plate type or a cylindrical type.

[0059]

Example 1 A cylindrical solid oxide fuel cell shown in FIG. 1 was used. That is, a strip-shaped interconnector 2, an electrolyte membrane 3, and a fuel electrode 4 on the electrolyte membrane were used on the cylindrical air electrode support 1 so as not to come into contact with the interconnector. As for the air electrode, the electrolyte membrane and the fuel electrode, as shown in FIG. 2, the air side electrode reaction layer 1a is provided between the air electrode and the electrolyte membrane, and the fuel side electrode reaction layer 4a is provided between the electrolyte membrane and the fuel electrode. The thing of the structure was used.

(1) Preparation of air electrode The composition of the air electrode was lanthanum manganite in which Sr represented by La _0.75 Sr _0.25 MnO ₃ composition was dissolved, and the air electrode material was prepared by coprecipitation and then heat-treated. A powder was obtained. Average particle size is 30 μm
Met. A cylindrical molded body was produced by an extrusion molding method. Further, it was fired at 1500 ° C. to obtain an air electrode support.

(2) Preparation of air side electrode reaction layer The composition of the air-side electrode reaction layer is La_0.75Sr_0.25MnO₃/
90 mol% ZrO₂-10mol% Sc ₂O₃And the weight ratio is 50 /
The one consisting of 50 was used. Each of La, Sr, Mn, Zr and Sc
Using an aqueous nitrate solution of
After that, oxalic acid was added to cause precipitation. Heat the precipitate further
After processing and controlling the particle size, a raw material powder was obtained. Average particle size
Was 2 μm. 40 parts by weight of the powder of the electrode reaction layer was mixed with a solvent (
(Tanol) 100 parts by weight, binder (ethyl cellulose)
2 parts by weight, dispersant (polyoxyethalene alkylsonate
Stell) 1 part by weight, defoamer (sorbitan sesquioleate) 1
After mixing with parts by weight, agitate well to adjust the slurry.
It was The viscosity of this slurry was 100 mPas. The slurry
The air electrode support (outer diameter 15 mm, wall thickness 1.5 mm, effective length
(400 mm) at 1400 ° C after film formation by slurry coating method
Sintered. The thickness was 20 μm.

(3) Preparation of material for electrolyte membrane The composition of the electrolyte membrane is 90 mol% ZrO₂-10mol% Sc₂O₃age
It was ZrO₂ Is dissolved in 3N or more concentrated nitric acid heated at 100 ℃.
And diluted with distilled water to obtain a nitrate aqueous solution. Sc₂O ₃
An aqueous nitrate solution was obtained by the same method. Each
Prepare an aqueous nitrate solution to the above composition and warm it to 80 ° C.
The aqueous oxalic acid solution was added and coprecipitated. Coprecipitate
The obtained liquid is dried at about 200 ° C, pyrolyzed at 500 ° C, and further
It was heat-treated at 900 ℃ for 10 hours. Powder with a bead mill
The material was crushed to obtain an electrolyte membrane material. BET value of electrolyte membrane material
Is 10 m²g^-1, Particle size distribution is 0.3 ~ 1.1μm and average particle size
Was 0.5 μm.

(4) Preparation of Electrolyte Membrane Slurry 40 parts by weight of the material is used as 100 parts by weight of solvent (ethanol), 2 parts by weight of binder (ethyl cellulose), 1 part by weight of dispersant (polyoxyetalene alkylsonate), and After mixing with 1 part by weight of a foaming agent (sorbitan sesquioleate), the mixture was thoroughly stirred to prepare a slurry. This slurry viscosity is 14
It was 0 mPas.

(5) Preparation of Electrolyte Membrane A film was formed on the air-side electrode reaction layer by a slurry coating method,
It was baked at 20 ° C. The thickness of the obtained electrolyte membrane was 30 μm. Note that masking was applied to a portion where an interconnector was formed in a later step so that the film was not applied.

(6) Preparation of slurry for fuel-side electrode reaction layer The composition of the fuel-side electrode reaction layer was NiO / 90 mol% ZrO ₂ -10 mol%
Sc ₂ O ₃ was used to prepare Ni, Zr and Sc nitrate aqueous solutions so as to have the above composition, and then oxalic acid was added to cause precipitation. The precipitate was further heat-treated to control the particle size to obtain a raw material. The composition and the weight ratio of the fuel side electrode reaction layer are NiO / 90 mol% ZrO ₂ -10 mol% Sc ₂ O ₃ = 20/80,
It was 0/50, and the average particle size was 0.5 μm in each case. 100 parts by weight of the powder, 500 parts by weight of an organic solvent (ethanol), 10 parts by weight of a binder (ethyl cellulose), 5 parts by weight of a dispersant (polyoxyetalene alkyl phosphate ester), 1 part by weight of a defoaming agent (sorbitane sesquiolate). Parts, plasticizer (D
After mixing 5 parts by weight of BP), the mixture was thoroughly stirred to prepare a slurry. The viscosity of this slurry was 70 mPas.

(7) Preparation of slurry of fuel electrode: The composition of the fuel electrode was NiO / 90 mol% ZrO ₂ -10 mol% Y ₂ O _3, and Ni, Z
Each of r and Y nitrate solutions was used to prepare the above composition, and then oxalic acid was added to cause precipitation. The precipitate was further heat-treated to control the particle size and obtain a raw material. Fuel electrode composition and its weight ratio are NiO / 90 mol% ZrO ₂
-10 mol% Y ₂ O ₃ = 70/30 and the average particle size was 2 μm. 100 parts by weight of the powder, 500 parts by weight of organic solvent (ethanol), 20 parts by weight of binder (ethyl cellulose), dispersant
After mixing 5 parts by weight of (polyoxyethalene alkyl phosphate), 1 part by weight of antifoaming agent (sorbitane sesquiolate) and 5 parts by weight of plasticizer (DBP), the mixture was sufficiently stirred to prepare a slurry. The viscosity of this slurry was 250 mPas.

(8) Preparation of fuel electrode Area of fuel electrode is 150 cm^TwoTo the battery so that
And the fuel-side electrode reaction layer is first coated by the slurry coating method.
Onto the electrolyte by NiO / 90 mol% ZrO₂-10mol% Sc₂O ₃ (flat
Uniform particle size) = 20/80 (0.5 μm), 50/50 (0.5 μm)
did. The film thickness (after firing) was 10 μm. On top of this,
The fuel electrode was formed into a film by the slurry coating method. Film thickness (baking
After) was 90 μm. Further, it was baked at 1400 ° C.

(9) Preparation of interconnector The composition of the interconnector was La _0.80 Ca _0.20 CrO ₃ and was obtained by subjecting it to lanthanum chromite in which Ca was solid-solved, prepared by spray pyrolysis, and then subjected to heat treatment. . The average particle size of the obtained powder was 1 μm. 40 parts by weight of the powder, 100 parts by weight of solvent (ethanol), binder (ethyl cellulose) 2
Parts by weight, dispersant (polyoxyethalene alkylsonate) 1 part by weight, defoamer (sorbitan sesquioleate)
After mixing with 1 part by weight, the slurry was sufficiently stirred to prepare a slurry. The viscosity of this slurry was 100 mPas. An interconnector was formed into a film by a slurry coating method and baked at 1400 ° C. The thickness after firing was 40 μm.

(10) Gas Leakage Test Nitrogen gas is flown into the inside of the air electrode support, and the inside of the air electrode is adjusted to 0.
A pressure of 1 MPa was applied and the amount of gas permeating through the electrolyte membrane was measured. From this, it was evaluated whether the electrolyte membrane was a membrane having no gas permeability. The portion where the electrolyte was not formed was sealed with a resin so as not to leak gas.

(Example 2) The pulverization conditions of a bead mill were controlled so that the BET value of the electrolyte membrane material was 5 m ² g ^-1 and the particle size distribution was 0.4.
~ 1.5 μm and Example except that the average particle size was 0.8 μm
Same as 1.

Example 3 The BET value of the material for the electrolyte membrane was 20 m ² g ⁻¹ and the particle size distribution was 0.1 by controlling the grinding conditions of the bead mill.
~ 0.9 μm and Example except that the average particle size was 0.3 μm
Same as 1.

Example 4 The pulverization conditions of the bead mill were controlled so that the BET value of the electrolyte membrane material was 10 m ² g ⁻¹ and the particle size distribution was 0.1.
~ 2.0 μm and Example except that the average particle size was 0.5 μm
Same as 1.

Example 5 The BET value of the material for the electrolyte membrane was 8 m ² g ⁻¹ and the particle size distribution was 0.1 by controlling the crushing conditions of the bead mill.
~ 2.0 μm and Example except that the average particle size was 1.0 μm
Same as 1.

(Example 6) The pulverization conditions of the bead mill were controlled, the BET value of the material for the electrolyte membrane was 8 m ² g ^-1 , and the particle size distribution was 0.1.
~ 2.0 μm and Example except that the average particle size was 1.1 μm
Same as 1.

(Example 7) The pulverization conditions of the bead mill were controlled so that the BET value of the electrolyte membrane material was 20 m ² g ^-1 and the particle size distribution was 0.1.
Example 1 was repeated except that the average particle size was ˜0.8 μm and the average particle size was 0.25 μm.

(Comparative Example 1) The BET value of the material for the electrolyte membrane was 4 m ² g ^-1 and the particle size distribution was 0.4 by controlling the grinding conditions of the bead mill.
~ 2.0 μm and Example except that the average particle size was 0.8 μm
Same as 1.

Comparative Example 2 The BET value of the material for the electrolyte membrane was 22 m ² g ⁻¹ and the particle size distribution was 0.1 by controlling the grinding conditions of the bead mill.
~ 0.8 μm and Example except that the average particle size was 0.3 μm
Same as 1.

Comparative Example 3 The BET value of the material for the electrolyte membrane is 10 m ² g ⁻¹ and the particle size distribution is 0.3 by controlling the crushing conditions of the bead mill.
~ 2.2 μm and Example except that the average particle size was 0.6 μm
Same as 1.

Example 1 was repeated except that the pulverization conditions of the bead mill were controlled, the BET value of the material for the electrolyte membrane was 11 m ² g ⁻¹ , the particle size distribution was 0.08 to 1.5 μm, and the average particle size was 0.5 μm. did.

[0080]

[Table 1]

Table 1 shows the results of the appearance and gas permeation amount of the electrolyte membrane with respect to the BET value, particle size distribution and average particle diameter of the material. In Examples 1 to 7, cracks are not seen in the appearance of the electrolyte membrane, and the gas permeation amount Q ≦ 2.8 × 10 ⁻⁹ ms ⁻¹ Pa ⁻¹
It was confirmed that the gas permeation required for the electrolyte membrane was reached. On the other hand, cracks were found in the electrolyte membrane in Comparative Example 2 and Comparative Example 4, it was found that the conditions are unsuitable as an electrolyte membrane, further cracks were not found in Comparative Examples 1 and 3 Gas permeation rate Q> 2.8
It became × 10 ^-9 ms ^-1 Pa ^-1 , and the gas permeability required for the electrolyte membrane was not obtained. From the above results, BET value of 5 ~
It was confirmed that it is preferable that the particle size distribution is 20 m ² g ⁻¹ and the particle size distribution is 0.1 to 2 μm. Further, in Examples 1 to 5, the gas permeation amount Q ≦ 2.8 × 10 ⁻¹⁰ ms ⁻¹ Pa ⁻¹ and the average particle size of these is in the range of 0.3 to 1.0 μm, and thus the average particle size is 0.3 to It was confirmed that 1.0 μm was more preferable.

Regarding solid solution amount of scandia (Example 8) The composition of the electrolyte membrane was 97 mol% ZrO ₂ -3 mol% Sc ₂ O.
_{The same} procedure as in Example 1 was performed except that the number was changed to ₃ .

Example 9 The composition of the electrolyte membrane was 88 mol% ZrO 2.
_{The same} procedure was performed as in Example 1 except that 2-12 mol% Sc ₂ O ₃ was used.

Example 10 The composition of the electrolyte membrane was set to 98 mol% Zr.
The same procedure was performed as in Example 1 except that O ₂ -2 mol% Sc ₂ O ₃ was used.

(Example 11) The composition of the electrolyte membrane was changed to 85 mol% Zr.
Same as Example 1 except that O ₂ -15 mol% Sc ₂ O ₃ was used.

(11) Power Generation Test A power generation test was carried out using the cells obtained in Example 1, Examples 8 to 11 and Comparative Example 1 (fuel electrode effective area: 150 cm ² ). The operating conditions at this time were as follows. Fuel: (H ₂ + 11% H ₂ O): N ₂ = 1: 2 Oxidizing agent: Air Power generation temperature: 900 ° C. Current density: 0.3 Acm ^-2

[0087]

[Table 2]

Table 2 shows Example 1, Examples 8 to 11 and Comparative Example 1
The result of the gas permeation amount of the electrolyte membrane and the result of the power generation test in FIG. In Examples 1 and 8 to 11, it was confirmed that the gas permeation amount of the electrolyte was Q ≦ 2.8 × 10 ⁻⁹ ms ⁻¹ Pa ⁻¹ and the gas permeation required for the electrolyte membrane was reached. Further, in Examples 1, 8 and 9, the gas permeation amount Q ≦
It was confirmed to be 2.8 × 10 ⁻¹⁰ ms ⁻¹ Pa ⁻¹ , which was more preferable. On the other hand, in terms of output performance, Example 1 was the best, followed by Examples 9 and 8, and Examples 10 and 11 showed slightly lower performance, but was confirmed to be superior to Comparative Example 1. It was From the above results, it was confirmed that if the BET value and the particle size distribution are proper, an electrolyte membrane having no gas permeability can be produced, and the output performance is superior to that of Comparative Example 1. From the results of the gas permeation amount and the output performance of the electrolyte membrane, it was confirmed that the solid solution amount of scandia is more preferably 3 to 12 mol%.

Regarding the solid solution amount of CeO ₂ (Example 12) The composition of the electrolyte membrane material was 89.5 mol% ZrO ₂ -10 m
Example 1 was repeated except that ol% Sc ₂ O ₃ -0.5 mol% CeO ₂ was used.

Example 13 The composition of the electrolyte membrane material was 88 mol.
% ZrO ₂ -10 mol% Sc ₂ O ₃ -2 mol% CeO ₂ Example 1
Same as.

Example 14 The composition of the electrolyte membrane material was 85 mol.
% ZrO ₂ -10 mol% Sc ₂ O ₃ -5 mol% CeO ₂ Example 1
Same as.

Example 15 The composition of the electrolyte membrane material was 89.7 m
ol% ZrO ₂ -10 mol% Sc ₂ O ₃ -0.3 mol% CeO ₂ was the same as in Example 1.

Example 16 The composition of the electrolyte membrane material was 84 mol.
% ZrO ₂ -10 mol% Sc ₂ O ₃ -6 mol% CeO ₂ Example 1
Same as.

[0094]

[Table 3]

Example 1 under the same conditions as in the power generation test method
2, power generation tests of Example 13, Example 14, Example 15, and Example 16 were performed. Table 3 shows the power generation test results. The output performance was higher in Examples 12 to 14 as compared with Example 1, but there was no change in Example 15 and it was rather worse in Example 16. From the above results, the solid solution amount of CeO ₂ is 0.5 to 5mo.
It was confirmed that the l% range was preferable.

Regarding the amount of solid solution of Bi ₂ O ₃ and CeO ₂ (Example 17) The composition of the electrolyte membrane material was 89.5 mol% ZrO ₂ -10 mol
Same as Example 1 except that% Sc ₂ O ₃ -0.2 mol% Bi ₂ O ₃ -0.3 mol% CeO ₂ was used.

(Example 18) The composition of the electrolyte membrane material was 88 mol%.
Example 1 was repeated except that ZrO ₂ -10 mol% Sc ₂ O ₃ -1 mol% Bi ₂ O ₃ -1 mol% CeO ₂ was used.

Example 19 The composition of the electrolyte membrane material was 85 mol%
Example 1 was repeated except that ZrO ₂ -10 mol% Sc ₂ O ₃ -2 mol% Bi ₂ O ₃ -3 mol% CeO ₂ was used.

Example 20 The composition of the electrolyte membrane material was 89.7 mol
% ZrO₂-10mol% Sc₂O₃-0.1mol% Bi₂O₃-0.2mol% CeO ₂age
The same as Example 1 except that

Example 21 The composition of the electrolyte membrane material is 84 mol% Z
The same procedure as in Example 1 was performed except that rO ₂ -10mol% Sc ₂ O ₃ -3mol% Bi ₂ O ₃ -3mol% CeO ₂ was used.

[0101]

[Table 4]

Example 1 under the same conditions as in the power generation test method
The power generation tests of 7, Example 18, Example 19, Example 20, and Example 21 were performed. Table 4 shows the power generation test results. The output performance was higher in Examples 17 to 19 as compared with Example 1, but there was no change in Example 20 and rather worse in Example 21. From the above results, the solid solution amount of Bi ₂ O ₃ + CeO ₂ is 0.
It was confirmed that the range of 5 to 5 mol% was preferable.

Heat Treatment Temperature and Grinding (Example 22) A material having a composition of 90 mol% ZrO ₂ -10 mol% Sc ₂ O ₃ was prepared by a coprecipitation method, then heat treated at 800 ° C. for 10 hours, and further ground by a bead mill. Then, a material for an electrolyte membrane was obtained. The electrolyte membrane material was prepared in the same manner as in Example 1 except that the BET value was 10 m ² g ^-1 , the particle size distribution was 0.3 to 1.1 μm, and the average particle size was 0.5 μm.

Example 23 A material having a composition of 90 mol% ZrO ₂ -10 mol% Sc ₂ O ₃ was prepared by a coprecipitation method, heat-treated at 1000 ° C. for 10 hours, and further pulverized by a bead mill to be used as an electrolyte membrane. Got the material. The BET value of the material for the electrolyte membrane is 10 m ² g ^-1 , and the particle size distribution is
Example 1 was repeated except that the average particle size was 0.3 to 1.1 μm and the average particle size was 0.5 μm.

Comparative Example 5 A material having a composition of 90 mol% ZrO ₂ -10 mol% Sc ₂ O ₃ was prepared by a coprecipitation method, then heat-treated at 750 ° C. for 10 hours, and further pulverized by a bead mill to prepare an electrolyte membrane. Got the material. BET value of the material for electrolyte membrane is 15 m ² g ^-1 , particle size distribution is 0.0
Example 1 was repeated except that the average particle size was 8 to 1.1 μm and the average particle size was 0.5 μm.

(Comparative Example 6) A material having a composition of 90 mol% ZrO ₂ -10 mol% Sc ₂ O ₃ was prepared by a coprecipitation method, then heat-treated at 1100 ° C. for 10 hours, and further pulverized with a bead mill to form an electrolyte membrane. Got the material. BET value of electrolyte membrane material is 10 m ² g ^-1 , particle size distribution is 0.2
.About.2.2 .mu.m and the average particle size was 0.6 .mu.m.

Comparative Example 7 A material having a composition of 90 mol% ZrO ₂ -10 mol% Sc ₂ O ₃ was prepared by a coprecipitation method, and then heat-treated at 900 ° C. for 10 hours to obtain a material for an electrolyte membrane. The electrolyte membrane material was prepared in the same manner as in Example 1 except that the BET value was 10 m ² g ^-1 , the particle size distribution was 0.3 to 4.5 μm, and the average particle size was 0.6 μm.

[0108]

[Table 5]

Example 1, Example 22, Example 23, Comparative Example 5,
The gas leakage test was performed on the batteries of Comparative Example 6 and Comparative Example 7. Table 5 shows the test results. Example 1, Example
In 22 and Example 23, the amount of gas permeation of the electrolyte Q ≦ 2.8 × 10 ⁻⁹
It was ms ⁻¹ Pa ⁻¹ , and it was confirmed that the gas permeation required for the electrolyte membrane was reached. On the other hand, in Comparative Example 5, cracks were generated in the electrolyte membrane, which increased the gas permeation amount. In Comparative Examples 6 and 7, there was no crack, but the gas permeation amount was not reached. From the above results, it was confirmed that the heat treatment of the material for the electrolyte membrane is preferably performed at 800 to 1000 ° C. and further pulverized.

Comparison with YSZ material (Comparative Example 8) The composition of the electrolyte membrane was 90 mol% ZrO ₂ -10 mol% Y ₂ O.
_{It was 3} . After heat treatment at 900 ° C. for 10 hours, it was pulverized with a bead mill and the BET value was 10 m ² g ⁻¹ , the particle size distribution was 0.3 to 1.1 μm, and the average particle size was 0.5 μm. Same as 1.

The following power generation tests were carried out on the batteries of Example 1 and Comparative Example 8. Fuel: (H ₂ + 11% H ₂ O): N ₂ = 1: 2 Oxidizing agent: Air Power generation temperature: 700 to 1000 ° C. Current density: 0.3Acm ^-2

FIG. 3 shows the output results of Example 1 and Comparative Example 8 at 700 to 1000 ° C. About 2W at 1000 ℃, but about 4W at 900 ℃, 10W at 800 ℃, 22 at 700 ℃
It can be seen that the difference in the output performance between Example 1 and Comparative Example 8 increases as the power generation temperature decreases about W. From the above results, if the SSZ material of the present invention is used for the electrolyte membrane of the solid oxide fuel cell, the output performance is superior to that of the battery using the conventional YSZ material for the electrolyte membrane of the solid oxide fuel cell, and 700 ° C. It was confirmed that a solid oxide fuel cell having high output performance even at a low temperature can be provided.

[0113]

EFFECTS OF THE INVENTION As is clear from the above description, since an SSZ material having a BET value of 5 to ²⁰ m ² g ^-1 and a particle size distribution of 0.1 to 2.0 μm was proposed, it has excellent sinterability. An SSZ material can be provided, and when the material is used as an electrolyte membrane of a solid oxide fuel cell, an electrolyte membrane having no gas permeability can be obtained.

Since the electrolyte membrane having no gas permeability could be obtained with the SSZ material, the solid oxide fuel having higher output performance than the solid oxide fuel cell which used the conventional YSZ material for the electrolyte membrane. A battery can be provided.

[Brief description of drawings]

FIG. 1 is a view showing a cross section of a cylindrical solid oxide fuel cell.

FIG. 2 is a cross-sectional view showing in detail the air electrode, electrolyte and fuel electrode configuration of the solid oxide fuel cell shown in FIG.

FIG. 3 is a graph showing the relationship between the power generation temperature (horizontal axis) and the initial output of the battery (vertical axis).

[Explanation of symbols]

1: Air electrode (support) 2: Interconnector 3: Electrolyte membrane 4: Fuel electrode 1a: Air side electrode reaction layer 4a: Fuel side electrode reaction layer

Claims (7)

[Claims] 1. A zirconia material in which scandia is dissolved, which has a BET value of 5 to ²⁰ m ² g ^-1 and a particle size distribution of 0.1 to 2.0 μm. 2. The scandia solid-solution zirconia material according to claim 1, wherein the scandia solid-solution zirconia material has an average particle diameter of 0.3 to 1.0 μm. 3. The scandia solid solution zirconia material according to claim 1, wherein the scandia solid solution amount of the scandia solid solution is 3 to 12 mol%. 4. The zirconia material in which scandia is solid-dissolved further has CeO ₂ solid-dissolved therein, and the solid-solution amount of the component is 0.5 to 5 mol%.
A zirconia material in which the scandia according to any one of items 1 to 4 is dissolved. The method according to claim 5 zirconia material was a solid solution of the scandia, further solid solution Bi ₂ O ₃ and CeO _2, and the Bi ₂ O ₃
Zirconia material was a solid solution of scandia according to any one of claims 1 to 3, wherein the sum of CeO ₂ solid solution amount is 0.5~5mol%. 6. The scandia solid solution according to any one of claims 1 to 5, wherein the scandia solid solution zirconia material is heat-treated at 800 to 1000 ° C. and pulverized. Made zirconia material. 7. A unit cell including an electrolyte membrane, a fuel electrode on one surface of the electrolyte membrane, and an air electrode provided on the opposite surface of the electrolyte membrane, and an electric cell connected to the air electrode or the fuel electrode surface. A solid oxide fuel cell comprising an interconnector having a role of electrical connection, wherein the electrolyte membrane is made of a zirconia material in which scandia as a solid solution according to any one of claims 1 to 6 is formed. And a solid oxide fuel cell.