JP2003208902A - Solid electrolyte-type fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolyte-type fuel cell in which an electrode activity is improved between an air electrode and an electrolyte, and which is superior in output performance. <P>SOLUTION: This cell is the solid electrolyte-type fuel cell which is provided with the air electrode, the electrolyte, and the fuel electrode, and in which an electrode reaction layer is interposed between the air electrode and the electrolyte, and the electrode reaction layer contains at least a catalyst of ionizing oxygen gas, and has a communicating open-air hole. Preferably, a micro pore diameter which the electrode reaction layer has is 0.1 to 10 μm, and the micro pore diameter which the electrode reaction layer has is smaller than that which the air electrode has. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a solid oxide fuel cell having excellent output performance. In particular, the present invention relates to a solid oxide fuel cell having excellent output performance even at an operating temperature of 700 to 900 ° C.

[0002]

2. Description of the Related Art A conventional solid oxide fuel cell uses lanthanum manganite in which Sr or Ca is dissolved as an air electrode material and zirconia (hereinafter referred to as YSZ) in which yttria is dissolved as an electrolyte material. Therefore, a battery in which an air electrode and an electrolyte are directly laminated is used. (See, for example, Non-Patent Document 1.) Further, by providing a thin layer of zirconia in which yttria is solid-solved between the electrolyte and the air electrode, the contact resistance between the air electrode and the electrolyte can be reduced, and the output performance can be improved. Some say it can be improved. (For example, Patent Document 1). Furthermore, a layer made of a mixed powder of lanthanum manganite having a solid solution of Ca and / or Sr and zirconia having a solid solution of yttria is provided between the air electrode and the electrolyte,
Some say that it is possible to reduce the contact resistance between the air electrode and the electrolyte and improve the output performance.
(For example, refer to Patent Document 2).

[0003]

[Non-Patent Document 1] Kazuo Fueki, Masao Takahashi [Fuel Cell Design Technology] Science Forum Publishing, September 30, 1987, P2
21-230

[Patent Document 1] JP-A-8-180886 (pages 1-4, FIG. 1)

[Patent Document 2] Japanese Patent Laid-Open No. 2000-44245 (pages 1-6)

[0004]

[Problems to be Solved by the Invention] With a structure in which lanthanum manganite in which Sr or Ca is solid-dissolved and YSZ having no gas permeability are laminated, this occurs between the air electrode and the electrolyte (1).
There is a problem that the reaction of the formula becomes a reaction only at the point where the electrolyte surface and the air electrode are in contact, and the output performance is low. _{^{O 2 + 4e - → 2O 2-}} ... (1)

If the methods of Patent Document 1 and Patent Document 2 are adopted, the output performance of the battery is improved by providing these layers if the operating temperature is about 900 to 1000 ° C. But,
When the operating temperature drops to about 700 ° C, the electrode activity of these materials decreases significantly, and the output performance of the cell is 900-1000.
There was a problem that the temperature was greatly reduced compared to the case of ℃.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a solid oxide fuel cell having improved electrode activity between an air electrode and an electrolyte and excellent output performance. .

[0007]

To achieve the above object, a first invention comprises an air electrode, an electrolyte and a fuel electrode, and an electrode reaction layer is interposed between the air electrode and the electrolyte. A solid oxide fuel cell in which the electrode reaction layer includes at least a catalyst for ionizing oxygen gas,
Providing to have open pores in communication.

According to the present invention, since the electrode reaction layer contains a catalyst for ionizing oxygen gas and has open pores communicating with each other, the output performance can be improved.

The reason for this is that the electrode reaction layer has a function of promoting the ionization of oxygen gas, so that the reaction of the formula (1) occurring between the air electrode and the electrolyte can be efficiently advanced,
This is because the output performance can be improved, and because it has open pores that communicate with each other, oxygen gas can be diffused throughout the electrode reaction layer, and the reaction of formula (1) can occur in the entire electrode reaction layer. This is because.

In order to achieve the above object, the second invention is
It is provided that the electrode reaction layer has a pore size of 0.1 to 10 μm.

According to the present invention, since the pore diameter in the electrode reaction layer is limited, the reaction of the formula (1) can be efficiently proceeded, and a solid oxide fuel cell having excellent output performance can be provided.

The reason for this is that if the pore size is smaller than 0.1 μm, there are almost no open pores communicating with each other in the electrode reaction layer, so that oxygen gas cannot be diffused into the electrode reaction layer, and the output performance deteriorates. When the pore diameter is larger than 10 μm, the number of contacts between the electrolyte and the electrode reaction layer is reduced, so that the adhesion is lowered, the contact resistance between the electrolyte and the electrode reaction layer is increased, and the output performance is lowered.

The pore size shown here is determined by the following method. Take a photograph of the cross section of the electrode reaction layer polished by SEM and copy it on a transparent film. The size of the void is measured, and for example, the diameter of the void corresponding to a circle is the pore diameter, and the diameter of a square is the length of one side as the pore diameter.

The term "pore diameter of 0.1 to 10 μm" as used herein means that the pore diameter of 100 pores was measured by the above-mentioned method, and the pore diameter was measured in the range of 3 to 97 when they were arranged in ascending order of diameter. Five
It corresponds to the 0th pore size. That is, in the range of 3% to 97% diameter, the pore diameter corresponding to 50% is 0.1
-10 μm.

In order to achieve the above object, the third invention is:
The pore size of the electrode reaction layer is provided to be smaller than the pore size of the air electrode.

According to the present invention, since the relationship between the electrode reaction layer and the pore diameter of the air electrode is limited, a solid oxide fuel cell having excellent output performance can be provided.

The reason for this is that the pore size of the electrode reaction layer is smaller than the pore size of the air electrode, so that the adhesion with the electrolyte is improved and the output performance is improved as compared with the case where the air electrode and the electrolyte are laminated. This is because

In order to achieve the above object, a fourth invention is:
It is provided that the porosity in the electrode reaction layer is 3 to 40%.

According to the present invention, since the porosity of the electrode reaction layer is limited, the reaction of formula (1) can be efficiently proceeded, and a solid oxide fuel cell having excellent output performance can be provided.

The reason for this is that if the porosity is less than 3%, the number of open pores communicating with each other in the electrode reaction layer is too small, so that oxygen gas cannot efficiently diffuse in the electrode reaction layer and the output performance deteriorates. On the other hand, when it is more than 40%, the contact between the electrolyte and the electrode reaction layer is reduced, so that the adhesiveness is lowered, the contact resistance between the electrolyte and the electrode reaction layer is increased, and the output performance is lowered.

The porosity shown here is obtained by the following method. Take a cross-sectional photograph of the electrode reaction layer portion polished by SEM, and trace the voids and particles on the transparent film in different colors. The color-coded films are subjected to image processing to calculate the ratio of voids.

In order to achieve the above object, a fifth invention is:
The porosity of the electrode reaction layer is equal to or less than the porosity of the air electrode.

According to the present invention, since the relationship between the porosity of the electrode reaction layer and the air electrode is limited, it is possible to provide a solid oxide fuel cell having excellent output performance.

This is because the porosity of the electrode reaction layer is less than the porosity of the air electrode, so that the adhesion with the electrolyte is improved and the output performance is improved as compared with the case where the air electrode and the electrolyte are laminated. Is.

A sixth invention for achieving the above object is as follows:
It is provided that the thickness of the electrode reaction layer is 3 to 50 μm.

According to the present invention, since the thickness of the electrode reaction layer is limited, the reaction of formula (1) can be efficiently proceeded, and a solid oxide fuel cell having excellent output performance can be provided.

The reason for this is that if the thickness of the electrode reaction layer is smaller than 3 μm, the number of reaction fields in which the reaction of the formula (1) can be performed is reduced, so that the output performance is deteriorated. This is because the output performance deteriorates because it cannot be efficiently diffused in the layer.

In order to achieve the above object, a seventh invention is:
It is provided that the thickness of the electrode reaction layer is 5 to 30 μm.

According to the present invention, since the thickness of the electrode reaction layer is further limited, the reaction of the formula (1) can be further efficiently proceeded, and a solid oxide fuel cell excellent in output performance can be provided.

The reason for this is that the thickness of the electrode reaction layer is 5 to 30 μm.
In the range of, there are many reaction fields where the reaction of formula (1) can be performed,
In addition, the oxygen gas can be efficiently diffused in the electrode reaction layer.

In order to achieve the above object, an eighth invention is:
The thickness of the electrode reaction layer is smaller than that of the cathode.

According to the present invention, since the relationship between the electrode reaction layer and the thickness of the air electrode is limited, it is possible to provide a solid oxide fuel cell having excellent output performance.

The reason for this is that if the electrode reaction layer is thicker than the air electrode, the reaction of formula (1) cannot proceed efficiently.

In order to achieve the above object, a ninth invention is:
The electrode reaction layer is a zirconia layer in which scandia is dissolved (hereinafter referred to as SSZ), a cerium oxide layer, and a layer in which zirconia in which scandia is dissolved and cerium oxide are uniformly mixed at a predetermined weight ratio ( Hereinafter, it is provided as any one of the group consisting of SSZ / cerium oxide).

According to the present invention, any one of SSZ, cerium oxide, and SSZ / cerium oxide is used as an electrode reaction layer.
Since it is a seed, it is possible to provide a solid oxide fuel cell excellent in output performance even at 900 ° C or lower.

The reason for this is that SSZ, cerium oxide, and SSZ / cerium oxide are higher than the oxygen ion conductivity of YSZ conventionally used for the electrode reaction layer.

The tenth invention for achieving the above object is as follows:
It is provided that the electrode reaction layer further contains a material having an electronic conductivity of 10 Scm ⁻¹ or more at 1000 ° C.

According to the present invention, since the electrode reaction layer further contains a material having high electron conductivity, the reaction of the formula (1) can be efficiently proceeded, and the solid oxide fuel cell excellent in output performance is obtained. Can be provided.

The reason for this is that the electrode reaction layer contains a material having high electron conductivity, so that the reaction represented by the formula (1) can be promoted. IR loss occurs in the electrode reaction layer when the electron conductivity is only a material smaller than 10 Scm ^-1 ,
This is because the reaction efficiency of the formula (1) decreases.

In order to achieve the above object, an eleventh invention is a layer in which an electrode reaction layer is a layer in which lanthanum manganite and zirconia in which scandia is dissolved as a solid solution are uniformly mixed at a predetermined weight ratio (hereinafter, lanthanum manganite). / SSZ)), a layer in which lanthanum manganite and cerium oxide are uniformly mixed at a predetermined weight ratio (hereinafter referred to as lanthanum manganite / cerium oxide), and lanthanum manganite and scandia are solid-dissolved. And a mixture of zirconia and cerium oxide uniformly mixed in a predetermined weight ratio (hereinafter referred to as lanthanum manganite / SSZ / cerium oxide). To do.

According to the present invention, a mixture of lanthanum manganite having a high electron conductivity and SSZ and / or cerium oxide having a high oxygen ion conductivity is selected as the electrode reaction layer. It is possible to provide a solid oxide fuel cell having excellent output performance even at a power generation temperature.

The reason for this is that lanthanum manganite, which has a high electron conductivity, is included, so that the reaction of the formula (1) can be promoted, and SSZ and cerium, which have a high oxygen ion conductivity even at a low temperature of about 700 ° C. Oxide, and SSZ /
This is because the cerium oxide is included and thus the generated oxygen ions can be efficiently transported to the electrolyte.

In order to achieve the above object, the twelfth invention provides that the solid solution amount of scandia in SSZ in the electrode reaction layer is 3 to 12 mol%.

According to the present invention, since the solid solution ratio of SSZ is limited, it is possible to provide a solid oxide fuel cell having excellent output performance even at a power generation temperature of about 700 to 900 ° C.

The reason why the solid solution amount of scandia is preferably 3 to 12 mol% is that the crystal phase in this range is stable and the oxygen ion conductivity is high. From the viewpoint of high oxygen ion conductivity, a solid solution of 8 to 12 mol% is more preferable.

The reason why the range other than 3 to 12 mol% is not preferable is that the oxygen ion conductivity is low at less than 3 mol% and the output performance is deteriorated at a low power generation temperature.
If it is more than the crystal phase, the rhombohedral phase precipitates in addition to the cubic crystal,
This is because the oxygen ion conductivity is reduced.

In order to achieve the above-mentioned object, a thirteenth invention is that SSZ in the electrode reaction layer further comprises CeO ₂ , Gd ₂ O ₃ and Y ₂
One of rare earth oxides such as O ₃ and Yb ₂ O ₃ and Bi ₂ O ₃ or
It is provided that two or more kinds of oxides are solid-solved, and the total amount of the oxides is 5 mol% or less.

According to the present invention, an appropriate amount of a rare earth oxide such as CeO ₂ , Gd ₂ O ₃ , Y ₂ O _3, Yb ₂ O ₃ and one or more oxides of Bi ₂ O ₃ are solid-dissolved. Therefore, it is possible to provide a solid oxide fuel cell having excellent output performance even at a power generation temperature of about 700 to 900 ° C.

The content of 5 mol% or less is preferable because at least one of the effects of increasing the oxygen ion conductivity and improving the sinterability of the material occurs. That is, if the oxygen ion conductivity is improved, the output performance is improved, and if the sinterability is improved, the low temperature sintering becomes possible. It is preferable to use a solid solution of two or more kinds because both oxygen ion conductivity and sinterability may be exerted. On the other hand 5 mol
This is because if it is contained in an amount of more than 0.1%, a rhombohedral phase is precipitated as a crystal layer in addition to the cubic crystal, and the oxygen ion conductivity is reduced.

In order to achieve the above object, the fourteenth invention is that the lanthanum manganite in the electrode reaction layer is LaAM
It is provided that the lanthanum manganite is represented by nO ₃ (however, either A = Ca or Sr).

According to the present invention, the electrode reaction layer is made of lanthanum manganite represented by LaAMnO ₃ (wherein A = Ca or Sr), so that it has high electronic conductivity and power generation at 700 to 900 ° C. It is possible to provide a solid oxide fuel cell having excellent output performance even at temperature.

The reason is that the electron conductivity is high and the material is stable in an air atmosphere at 700 ° C. or higher.

In order to achieve the above object, the fifteenth invention provides that the cerium oxide in the electrode reaction layer is of the general formula (CeO
₂ ) _1-2X (B ₂ O ₃ ) _X (however, B = Sm, Gd, Y any one, 0.05
≦ X ≦ 0.15) is provided.

According to the present invention, since the composition of cerium oxide is limited, it is possible to provide a solid oxide fuel cell having excellent output performance even at a power generation temperature of about 700 to 900 ° C.

The reason is that the composition represented by the general formula (CeO ₂ ) _1-2X (B ₂ O ₃ ) _X (provided that any one of B = Sm, Gd and Y, 0.05 ≦ X ≦ 0.15) is This is because the oxygen ion conductivity is high and the reaction of the formula (1) can be efficiently advanced even at about 700 ° C.

In order to achieve the above object, the sixteenth invention provides that the electrolyte is YSZ or SSZ.

According to the present invention, since the electrolyte material is YSZ or SSZ, it is possible to provide a solid oxide fuel cell capable of obtaining high output performance even at 700 to 900 ° C.

The reason for this is that YSZ and SSZ have high oxygen ion conductivity and are stable as materials. From the viewpoint of high oxygen ion conductivity, yttria in which an appropriate amount is dissolved and zirconia in which scandia is dissolved are preferable.

In order to achieve the above object, the seventeenth invention provides that the air electrode is lanthanum manganite represented by LaAMnO ₃ (provided that either A = Ca or Sr). .

According to the present invention, since the composition of the air electrode is limited, it is possible to provide a solid oxide fuel cell having excellent output performance even at a power generation temperature of 700 to 900 ° C.

The reason for this is that the electron conductivity is high and the material is stable in an air atmosphere at 700 ° C. or higher.

In order to achieve the above object, the eighteenth aspect of the invention is that the fuel electrode has a layer (hereinafter, referred to as NiO / YS) in which zirconia, which is a solid solution of NiO and yttria, is uniformly mixed.
Denote by Z. ) Is provided.

According to the present invention, since the fuel electrode is NiO / YSZ, it is possible to provide a solid oxide fuel cell having excellent output performance.

The reason for this is that since Ni is contained, the electron conductivity is high, and because YSZ is mixed, the agglomeration of Ni can be suppressed and the durability is excellent. The NiO / YSZ shown here is a layer in which NiO and YSZ are uniformly mixed in a predetermined weight ratio.

In order to achieve the above object, the nineteenth invention is a layer in which zirconia containing NiO and scandia as a solid solution is uniformly mixed in a predetermined weight ratio between the fuel electrode and the electrolyte (hereinafter, referred to as , NiO / SSZ)) is interposed.

According to the present invention, the electrolyte side is provided with a layer in which SSZ having higher oxygen ion conductivity than YSZ is mixed with NiO.
It is possible to provide a solid oxide fuel cell having excellent output performance even at an operating temperature of 700 ° C.

The reason for this is that if the oxygen ion conductivity of the fuel side electrode reaction layer is high, it occurs between the electrolyte and the fuel electrode (3),
This is because equation (4) can be advanced efficiently. 700 ° C
The output performance is excellent even at a moderate operating temperature because the oxygen ion conductivity of SSZ is sufficiently high even at 700 ° C.
Incidentally, NiO in NiO / SSZ and NiO / YSZ is reduced to Ni under the operating atmosphere of the fuel cell, and the layer is Ni / SSZ and Ni.
/ YSZ. ^{_{H 2 + O 2- → H 2}} O + 2e - ... (3) CO + O 2- → CO 2 + 2e - ... (4)

In order to achieve the above object, the 20th invention provides that the interconnector is a lanthanum chromite containing Ca as a solid solution.

According to the present invention, the use of lanthanum chromite containing Ca as a solid solution makes it possible to easily produce a film having no gas permeability and to produce an interconnector having high electronic conductivity.

The reason for this is that lanthanum chromite containing a solid solution of a substance other than Ca requires firing at a temperature higher than 1500 ° C. in order to form a film having no gas permeability, and at this temperature, a solid oxide fuel cell is required. This is because firing of causes a reaction between other constituent materials and reduces output performance.

The membrane having no gas permeability shown here is evaluated by the gas permeation amount permeating between the one side and the opposite side of the interconnector, and the gas permeation amount Q ≦ 2.8 × 10 5. ^-9 ms ^-1 Pa ^-1 (more preferably Q ≦ 2.8 × 10
^-10 ms ^-1 Pa ^-1 ).

[0072]

BEST MODE FOR CARRYING OUT THE INVENTION A solid oxide fuel cell according to the present invention will be described with reference to FIG. FIG. 1 is a view showing a cross section of a cylindrical solid oxide fuel cell. A strip-shaped interconnector 2 and an electrolyte 3 are provided on a cylindrical air electrode support 1, and a fuel electrode 4 is provided on the electrolyte 3 so as not to come into contact with the interconnector 2. When Air is supplied to the inside of the air electrode support and fuel is supplied to the outside, oxygen in Air is converted into oxygen ions at the interface between the air electrode and the electrolyte, and the oxygen ions reach the fuel electrode through the electrolyte. And
Fuel gas and oxygen ions react to produce water and carbon dioxide. These reactions are shown by the equations (3) and (4). Fuel pole 4
Electricity can be extracted to the outside by connecting the and the interconnector 2. ^{_{H 2 + O 2- → H 2}} O + 2e - ... (3) CO + O 2- → CO 2 + 2e - ... (4)

FIG. 2 is a sectional view showing a type in which an electrode reaction layer 5 is provided between the air electrode 1 and the electrolyte 3 and a fuel side electrode reaction layer 6 is provided between the electrolyte 3 and the fuel electrode 4. The electrode reaction layer 5 is a layer provided to efficiently perform the reaction of the formula (1) in which oxygen ions are generated from oxygen gas and electrons from the air electrode side, and the oxygen ions generated in this electrode reaction layer are electrolytes. To the fuel electrode side. Then, the reactions shown in the equations (3) and (4) are performed in the fuel-side electrode reaction layer 6, and the fuel electrode 4
Electricity can be extracted to the outside by connecting the and the interconnector 2. Therefore, the electrode reaction layer, the electrolyte, and the fuel side electrode reaction layer are important for obtaining high output characteristics up to a low temperature of about 700 ° C. _{^{O 2 + 4e - → 2O 2-}} ... (1)

The role of the electrode reaction layer in the present invention is to efficiently perform the reaction of the formula (1) in the air atmosphere of the solid oxide fuel cell. For this purpose, the electrode reaction layer is required to include at least a catalyst for ionizing oxygen gas and have open pores communicating with each other. In order to improve the reaction efficiency, it is preferable to optimize the pore size and the porosity. From this viewpoint, the electrode reaction layer preferably has a small pore size and a large porosity.

The electrode reaction layer in the present invention is not particularly limited as long as it contains at least a catalyst for ionizing oxygen gas. Examples include lanthanum manganite represented by LaAMnO ₃ (A = Sr or Ca), lanthanum cobaltite represented by LaSrCoFeO ₃ , YSZ, SSZ, and the like. The composition of the electrode reaction layer may be the same as that of the air electrode.

The material for the electrode reaction layer preferably has high oxygen ion conductivity. Further, it is more preferable that the electrode reaction layer further has electronic conductivity because the reaction of the formula (1) can be further promoted. Further, it is preferable that the material has a thermal expansion coefficient close to that of the electrolyte material, low reactivity with the electrolyte and the air electrode, and good adhesion.
A good material for all these properties is 700
It is possible to obtain high output characteristics even at a low temperature of about ° C. From the above viewpoint, SSZ and / or cerium oxide, lanthanum manganite / SSZ, lanthanum manganite / cerium oxide, SSZ / cerium oxide, lanthanum manganite / SSZ / cerium oxide and the like are preferable.

In the present invention, the catalyst for ionizing the oxygen gas contained in the electrode reaction layer preferably contains a material having high oxygen ion conductivity. The reason for this is that if a material having a high oxygen ion conductivity is contained, the oxygen ions generated in the electrode reaction layer can be efficiently transported to the electrolyte. From this viewpoint, as the oxygen ion conductivity,
It is preferably 0.1 Scm ^-1 or more at 1000 ° C.

As the material having oxygen ion conductivity of 0.1 Scm ⁻¹ or more at 1000 ° C., SSZ, cerium oxide, a mixed layer of SSZ and cerium oxide, YSZ, (La _1-x Sr _x Ga _1-y Mg _y O ₃ )
_Examples include lanthanum gallate represented by (La _1-x Sr _x Ga _1-y-z Mg _y Co _z O ₃ ). Further, a mixture of SSZ and lanthanum gallate, a mixture of SSZ with CeO ₂ , Bi ₂ O ₃ or the like as a solid solution, and the like are also suitable, and therefore preferable.

There is no particular limitation on the material having an electronic conductivity of 10 Scm ⁻¹ or more at 1000 ° C., which is contained in the electrode reaction layer in the present invention. _{LaAMnO 3 (A = Sr or Ca} ) represented by lanthanum manganite, lanthanum cobaltite represented by _{LaSrCoFeO 3, LaSrFeO 3, LaSrFeCoO 3} , LaNiO 3, SmSrCoO 3, Gd
Examples include SrCoO ₃ .

Although lanthanum manganite represented by LaAMnO ₃ (A = Sr or Ca) is preferred as the lanthanum manganite in the electrode reaction layer in the present invention, 70
Due to electronic conductivity and material stability at 0 ° C and above (La
_1-x Ax) _y The values of x and y in MnO ₃ are 0.15 ≦ x ≦ 0.3, 0.97 ≦ y
The range of ≦ 1 is more preferable.

The reason for this is that the electron conductivity decreases in the range of x <0.15 and x> 0.3, and the reactivity becomes high and the activity of the electrode reaction layer decreases when y <0.97. This is because it reacts with zirconia to form an insulating layer represented by La ₂ Zr ₂ O ₇ and reduces the output performance of the cell.

The lanthanum manganite in the electrode reaction layer in the present invention is Ce, Sm, Gd, Pr, Nd, Co, Al, Fe, Cr, Ni, C.
It may be a solid solution of a, Sr, or the like.

Raw materials used for the electrode reaction layer in the present invention
The average particle diameter of the powder is 0.5 to 10 μm, and the BET value is 0.5 to
20m²g^-1A degree is preferable. The reason for this is that the average particle size is 0.
In the electrode reaction layer consisting of raw material smaller than 5 μm
Oxygen gas diffusion is low because there are almost no pores,
This is because the reaction of formula (1) cannot be carried out efficiently.
Electrode reaction layer composed of raw material larger than 10 μm
Has low sinterability and poor adhesion to air electrode and electrolyte
The output performance is reduced. On the other hand, BET value is 0.5m
²g^-1In the electrode reaction layer composed of smaller ones, (1)
High output performance is obtained because there are few active points that cause the equation reaction
The BET value is 20m²g^-1Bigger one
The formed electrode reaction layer has few open pores
Therefore, the diffusion of oxygen gas is low and the reaction of equation (1) can be performed efficiently.
This is because it cannot be done easily.

The electrode reaction layer in the present invention may have a structure in which the average particle diameter of the raw material powder and the BET value are inclined in order to enhance the electrode activity. For example, 5 [mu] m average particle size from the air electrode side to the electrolyte direction, 3 [mu] m, 1 [mu] m to be or BET value ^{1m 2 g -1, 3m 2 g} -1, 5m 2 g - may be as a ^1. From the viewpoint of efficiently carrying out the reaction of the formula (1), an electrode reaction layer composed of a material having an inclined average particle diameter or BET value is preferable.

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. Furthermore, the average particle size is
Shimadzu laser diffraction particle size distribution analyzer SALD-200
It is the value of the median diameter (50% diameter) obtained by measurement using 0.

In the electrode reaction layer of the present invention, the weight ratio of the mixture of lanthanum manganite / SSZ or the like is preferably about 10/90 to 90/10. The reason for this is SSZ
When the weight ratio of is less than 10% by weight, the oxygen ion conductivity in the electrode reaction layer is reduced, oxygen ions generated by the formula (1) cannot be efficiently sent to the electrolyte, and the output performance is reduced. On the other hand, if the weight ratio of SSZ is more than 90% by weight, the electron conductivity in the electrode reaction layer is lowered, and the reaction represented by the formula (1) is hard to occur.

When a mixture of lanthanum manganite / SSZ or the like is used in the electrode reaction layer of the present invention, the composition may be graded to enhance the electrode activity. For example, from the air electrode side toward the electrolyte, lanthanum manganites / S
SZ: Things like 80/20, 50/50, 20/80 are also acceptable.

There is no particular limitation on the method for preparing the raw material for the electrode reaction layer in the present invention. For SSZ, cerium oxide and lanthanum manganite, methods of producing by a powder mixing method, coprecipitation method, spray pyrolysis method, sol-gel method and the like can be mentioned.

In the case of synthesizing the raw materials in the mixture of lanthanum manganite / SSZ, the respective materials are separately prepared, and then mixed by a wet method such as a spray drying method, and further heat treated to obtain a mixture. And a method of mixing by a dry method of mixing using a universal stirring mixer or the like and further heat-treating to obtain a mixture.

The electrolyte in the present invention preferably has high oxygen ion conductivity, no gas permeability, and no electron conductivity in the air atmosphere and the fuel gas atmosphere of the solid oxide fuel cell. From this viewpoint, zirconia in which yttria or scandia is dissolved is preferable. Also,
It may be zirconia which is a solid solution of yttria and scandia.

The solid solution amount of yttria and scandia in YSZ and SSZ in the present invention is preferably about 3 to 12 mol.

The reason why the solid solution range of yttria is preferably 3 to 12 mol% is that the oxygen ion conductivity is lowered when it is less than 3 mol%, while the crystal phase of cubic crystal is other than cubic when it is more than 12 mol%. This is because the rhombohedral crystal phase is precipitated in and the oxygen ion conductivity is reduced.

However, the solid solution amount of yttria is 3 to 12 mol%.
Even in the range, the oxygen ion conductivity is high in the range of 900 to 1000 ° C, but greatly decreases below 900 ° C. Therefore 700
When YSZ is used as an electrolyte at a low temperature of about ℃, it is preferable to use it as a thin film.

The reason for this is that the use of a thin film can reduce the resistance loss inside the electrolyte and obtain a high output performance even at 700 ° C.

The thin film shown here means that the thickness of the electrolyte is 50 μm.
Indicates less than m.

On the other hand, the scandia solid solution range is 3 to 12 mol.
The reason for limiting to 10% is that if it is less than 3 mol%, the oxygen ion conductivity will be low. On the other hand, if it is more than 12 mol%, the crystal phase will be cubic and rhombohedral phases will precipitate, and the oxygen ion conductivity will be reduced. This is because the

The reason why the solid solution range of scandia is preferable is that
This is because the crystal phase is stable and the oxygen ion conductivity is high in this composition range. From the viewpoint of high oxygen ion conductivity, scandia solid solution containing 8 to 12 mol% is more preferable.

The electrolyte having no gas permeability shown here is
A pressure difference is provided between one side and the other side of the electrolyte, and the amount of gas permeated through the gap is evaluated, and the amount of gas permeation Q ≦ 2.
^{8 × 10 - 9 ms -1 Pa} -1 ( more preferably ^{Q ≦ 2.8 × 10 -10 ms -1} P
a ^-1 ).

CeO ₂ , Sm ₂ O ₃ , and Gd ₂ are used as the electrolyte in the present invention.
It may be a solid solution of O _3, Bi ₂ O ₃ or the like in an amount of 5 mol% or less. In particular, in zirconia containing solid solution of scandia, it is preferable that a small amount of these compositions is contained because oxygen ion conductivity becomes high and low temperature sintering becomes possible. Further, a small amount of a sintering aid may be added to produce an electrolyte having no gas permeability. Examples of the sintering aid include Al ₂ O ₃ and SiO ₂ .

The method for producing the electrolyte raw material in the present invention is not particularly limited as long as it is a method capable of uniformly forming the solid solution of scandia or yttria. The coprecipitation method is common.

The air electrode in the present invention preferably has a high electron conductivity and a high oxygen gas permeability in the air atmosphere of the solid oxide fuel cell. From this viewpoint, lanthanum manganite represented by LaAMnO ₃ (A = Sr or Ca), lanthanum cobaltite represented by LaSrCoFeO ₃ , LaSr
FeO ₃ , LaSrFeCoO ₃ , LaNiO ₃ , SmSrCoO ₃ , GdSrCoO _{3 and the} like are preferable.

As the air electrode in the present invention, LaAMnO ₃ (A =
Although lanthanum manganite represented by (Sr or Ca) is preferred, the value of x, y in (La _1-x Ax) _y MnO ₃ is 0.15 ≦ because of the electronic conductivity at 700 ° C. or higher and the stability of the material. x
The range of ≦ 0.3 and 0.97 ≦ y ≦ 1 is more preferable.

The reason is that the electron conductivity is lowered in the range of x <0.15 and x> 0.3, and the activity of the electrode reaction layer is lowered in the case of y <0.97. When y> 1, it reacts with zirconia. This is because the output performance of the cell is deteriorated because the insulating layer represented by La ₂ Zr ₂ O ₇ is produced.

The lanthanum manganite at the air electrode in the present invention is Ce, Sm, Gd, Pr, Nd, Co, Al, Fe, Cr, Ni, Ca, Sr.
It may be a solid solution of the above.

The method for producing the air electrode raw material in the present invention is not particularly limited. Examples thereof include a powder mixing method, a coprecipitation method, a spray pyrolysis method, and a sol-gel method.

The pore diameter of the air electrode in the present invention is not particularly limited as long as it is larger than the pore diameter of the electrode reaction layer, but other characteristics include high electron conductivity and high oxygen content. Those having gas permeability and good adhesion to the electrode reaction layer are preferable. Further, in the type shown in the present embodiment in which the air electrode is used as a support, the air electrode itself is required to have strength, and therefore, one having higher strength is preferable. From these viewpoints, as the pore size of the air electrode,
2 to 30 μm, 2 to 20 considering high strength
About μm is preferable.

The porosity of the air electrode in the present invention is not particularly limited as long as it is equal to or higher than the porosity of the electrode reaction layer, but other characteristics include high electron conductivity and high oxygen gas permeability. It is preferable that the resin has good properties and has good adhesion to the electrode reaction layer. Further, in the type shown in the present embodiment in which the air electrode is used as a support, the air electrode itself is required to have strength, and therefore, one having higher strength is preferable.
From this viewpoint, the porosity of the air electrode is about 10 to 50%,
Considering that it has high strength, it is preferably about 10 to 45%.

The thickness of the air electrode in the present invention is not particularly limited as long as it is thicker than the electrode reaction layer, but other characteristics include high electron conductivity, high oxygen gas permeability, and It is preferable that the adhesiveness to the reaction layer is good. Further, in the type shown in the present embodiment in which the air electrode is used as a support, the air electrode itself is required to have strength, and therefore, one having higher strength is preferable. From this viewpoint, the thickness of the air electrode is preferably about 30 μm to 3 mm, and considering the case of a support, the thickness is preferably about 1 to 3 mm.

Having high strength as shown here is radial crushing strength.
It indicates a material that exhibits 10 MPa or more. The radial crushing strength was measured by the following test.

The sample was placed between the compression jigs of the tester, pressed from above and below to be destroyed, and the load value at that time was used to calculate from the following formula. σr = P × (D−d) / (I × d ² ) ... (5) (σr: radial crushing strength, P: breaking load, D: sample outer diameter, d:
Wall thickness, I: sample length)

The fuel electrode in the present invention has high electronic conductivity and high fuel gas permeability in the fuel gas atmosphere of the solid oxide fuel cell, and can efficiently carry out the reactions of the formulas (3) and (4). Is preferred. From this viewpoint, NiO / YSZ and the like can be cited as preferable materials. NiO is reduced to Ni during power generation of the solid oxide fuel cell, and the layer becomes Ni / YSZ.

From the viewpoint that the reactions of the equations (3) and (4) can be carried out efficiently and the output performance is improved, it is preferable to provide the fuel side electrode reaction layer between the electrolyte and the fuel electrode.

As the fuel-side electrode reaction layer in the present invention, Ni, which is excellent in both electronic conductivity and oxygen ion conductivity, is used.
O / SSZ is preferred. NiO is reduced to Ni during power generation of the solid oxide fuel cell, and the layer becomes Ni / SSZ. Also, Ni
The O / SSZ ratio is preferably 10/90 to 50/50 by weight. The reason for this is that the electronic conductivity is too low below 10/90,
On the other hand, when it exceeds 50/50, the oxygen ion conductivity is too low.

The solid solution amount of scandia of SSZ in NiO / SSZ of the present invention is preferably 3 to 12 mol%. The reason is that oxygen ion conductivity is high in this range (3), (4)
This is because the reaction can be promoted. Further, since the oxygen ion conductivity is high even at a low temperature of about 700 ° C., it is possible to provide a solid oxide fuel cell having high output performance up to a low temperature of about 700 ° C.

Ce is added to SSZ in NiO / SSZ of the present invention.
O ₂ , Sm ₂ O ₃ , Gd ₂ O ₃ , Bi ₂ O _{3 and the} like may be solid-dissolved in an amount of about 5 mol% or less. Also, two or more kinds of solid solutions may be used. Since it is expected that not only the improvement of the oxygen ion conductivity but also the improvement of the electronic conductivity under the fuel gas atmosphere can be expected when these materials are solid-dissolved, it is preferable to include them.

A layer in which NiO, SSZ, and cerium oxide are uniformly mixed at a predetermined weight ratio (hereinafter referred to as NiO / SSZ /) from the viewpoints of high oxygen ion conductivity and high electron conductivity in a fuel gas atmosphere. Cerium oxide). NiO is reduced to Ni during power generation of the solid oxide fuel cell, and the layer becomes Ni / SSZ / cerium oxide.

The cerium oxide shown here is not particularly limited as long as it is an oxide containing cerium. General formula
(CeO ₂ ) _1-2X (B ₂ O ₃ ) _X (However, any one of B = Sm, Gd, Y,
The one represented by 0.05 ≦ X ≦ 0.15) has high oxygen ion conductivity, which is preferable.

The fuel electrode in the present invention preferably has high electron conductivity in order to reduce IR loss. From this viewpoint, the weight ratio of NiO / YSZ is preferably 50/50 to 90/10. The reason for this is that if it is less than 50/50, the electronic conductivity is low, while if it exceeds 90/10, the output performance deteriorates due to the agglomeration of Ni particles.

Regarding the composition of the fuel electrode in the present invention,
In addition to NiO / YSZ, NiO / SSZ or zirconia in which NiO / calcium is dissolved (hereinafter referred to as NiO / CSZ) may be used. YS from SSZ
YSZ is preferred because Z is cheaper, but CSZ
NiO / CSZ is the most preferable from the viewpoint of cost because is cheaper than YSZ. Note that NiO / CSZ also becomes Ni / CSZ in fuel cell power generation.

The method for synthesizing the fuel electrode raw material in the present invention is not particularly limited as long as the fuel electrode materials such as NiO / SSZ and YSZ are uniformly mixed. A coprecipitation method, a spray dry method, etc. are mentioned.

The interconnector of the present invention preferably has high electron conductivity, no gas permeability, and no oxygen ion conductivity in the air atmosphere and the fuel gas atmosphere of the solid oxide fuel cell. From this viewpoint, lanthanum chromite is preferable.

Since lanthanum chromite is difficult to sinter, it is difficult to produce 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 solid solution amount of lanthanum chromite in which Ca is used as a solid solution used in the interconnector of the present invention. The larger the solid solution amount of Ca, the higher the electronic conductivity, but the stability of the material decreases, so the solid solution amount of Ca is preferably about 10 to 40 mol%.

Regarding the method for producing the interconnector raw material in the present invention, it is preferable that the composition of lanthanum chromite in which Ca is dissolved is made uniform. From this viewpoint, the spray pyrolysis method and the citrate method are preferable.

The shape of the solid oxide fuel cell of the present invention is not particularly limited, and it may be either a flat plate type or a cylindrical type. In the flat plate type, the interconnector is called a separator and has the same role as the interconnector. In the case of a separator, a metal such as stainless steel may be used.

The solid oxide fuel cell according to the present invention is of a microtube type (outer diameter of 10 mm or less, more preferably 5 mm or less).
mm or less) is also applicable.

[0127]

Example 1 Example 1 A cylindrical solid oxide fuel cell shown in FIG. 1 was used. That is, a belt-shaped interconnector 2, an electrolyte 3, and a fuel electrode 4 on the electrolyte so as not to come into contact with the interconnector were used on a cylindrical air electrode support 1. As shown in FIG. 2, an electrode reaction layer 5 was formed between the air electrode and the electrolyte, and a fuel side electrode reaction layer 6 was formed between the fuel electrode 4 and the electrolyte 3.

(1) Preparation of air electrode support The composition of the air electrode is lanthanum manganite in which Sr represented by La _0.75 Sr _0.25 MnO ₃ composition is dissolved, and the air electrode is prepared by heat treatment after coprecipitation. An electrode raw material powder was obtained. Average particle size is 30μ
It was m. A cylindrical molded body was produced by an extrusion molding method. Further, it was fired at 1500 ° C. to obtain an air electrode support. The pore size of the air electrode support was 14 μm, the porosity was 45%, and the wall thickness was 1.5 mm.

(2) Preparation of electrode reaction layer The electrode reaction layer was lanthanum manganite / SSZ,
The composition and the weight ratio thereof are La _0.75 Sr _0.25 MnO ₃
/ 90 mol% ZrO ₂ -10 mol% Sc ₂ O ₃ = 50/50 was used. La, Sr, M
After using each of the aqueous nitrate solutions of n, Zr and Sc to prepare the above composition, oxalic acid was added to cause precipitation.
The precipitate was further heat-treated to control the particle size to obtain a raw material powder. The average particle size was 2 μm. The electrode reaction layer powder
40 parts by weight are mixed with 100 parts by weight of solvent (ethanol), 2 parts by weight of binder (ethyl cellulose), 1 part by weight of dispersant (polyoxyethalene alkylsonate), 1 part by weight of defoaming agent (sorbitan sesquioleate). After that, it was sufficiently stirred to prepare a slurry. This slurry viscosity is 100mPa
It was s. The above slurry was used as an air electrode support (external diameter 15 m
m, wall thickness 1.5 mm, effective length 400 mm) was formed into a film by the slurry coating method and then sintered at 1400 ° C. The thickness was 20 μm.

(3) Preparation of electrolyte slurry: The electrolyte material was SSZ, and the composition was 90 mol% ZrO ₂ -10 mol% Sc ₂ O ₃ . ZrO ₂ was dissolved in 3N or more concentrated nitric acid heated at 100 ° C. and diluted with distilled water to obtain a nitrate aqueous solution. Sc ₂ O ₃
An aqueous nitrate solution was obtained by the same method. Each nitrate aqueous solution was prepared so as to have the above composition, an oxalic acid aqueous solution was added, and coprecipitation was performed. 200 liquid obtained by co-precipitation
It was dried at about ℃, pyrolyzed at 500 ℃, and further heat-treated at 800 ℃ for 10 hours to obtain raw material powder. The average particle size was 0.5 μm. 40 parts by weight of the powder is 100 parts by weight of a solvent (ethanol),
After mixing 2 parts by weight of a binder (ethyl cellulose), 1 part by weight of a dispersant (polyoxyetalene alkylsonate), and 1 part by weight of a defoaming agent (sorbitan sesquioleate), the mixture was sufficiently stirred to prepare a slurry. The viscosity of this slurry was 140 mPas.

(4) Preparation of Electrolyte A film was formed on the electrode reaction layer by a slurry coating method and baked at 1400 ° C. The thickness of the obtained electrolyte 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.

(5) Preparation of Slurry for Fuel Side Electrode Reaction Layer The material for the fuel side electrode reaction layer was NiO / SSZ, and the composition was NiO / 90 mol% ZrO ₂ -10 mol% Sc ₂ O ₃ , Ni, Zr and
After using each nitrate Sc aqueous solution to prepare the above composition, oxalic acid was added for precipitation. The precipitate was further heat-treated to control the particle size to obtain a raw material. The composition of the fuel side electrode reaction layer and its weight ratio are NiO / 90 mol%
_Two types of ZrO ₂ -10 mol% Sc ₂ O ₃ = 20/80 and 50/50 were prepared, and the average particle diameters were both 0.5 μm. The powder 100
Parts by weight and 500 parts by weight of organic solvent (ethanol), 10 parts by weight of binder (ethyl cellulose), 5 parts by weight of dispersant (polyoxyetalene alkyl phosphate ester), 1 part by weight of antifoaming agent (sorbitane sesquiolate), plastic Agent (DBP) 5
After mixing the parts by weight, the slurry was sufficiently stirred to prepare a slurry. The viscosity of this slurry was 70 mPas.

(6) The cell was masked so that the preparation area of the fuel side electrode reaction layer was 150 cm ² .
NiO / 90 mol% ZrO ₂ -1 onto electrolyte by slurry coating method
0mol% Sc ₂ O ₃ (average particle size) = 20/80 (0.5 μm), 50/50 (0.5
(μm) in order. The film thickness (after firing) was 10 μm.

(7) Preparation of fuel electrode slurry: The material of the fuel electrode was NiO / YSZ, and the composition was NiO / 90 mol% ZrO ₂ -10 mol
% Y ₂ O _3, and using Ni, Zr, and Y nitrate aqueous solutions to prepare the above composition, oxalic acid was added to cause precipitation. The precipitate was further heat-treated to control the particle size and obtain a raw material. Composition and weight ratio are NiO / 90
mol% ZrO ₂ -10mol% Y ₂ O ₃ = 70/30, average particle size 5μm
Met. 100 parts by weight of the powder and an organic solvent (ethanol) 5
00 parts by weight, binder (ethyl cellulose) 20 parts by weight,
Dispersant (polyoxyethalene alkyl phosphate) 5
After mixing 1 part by weight, 1 part by weight of a defoaming agent (sorbitan sesquiolate) and 5 parts by weight of a plasticizer (DBP), the mixture was sufficiently stirred to prepare a slurry. The viscosity of this slurry is 250 mPas
Met.

(8) Preparation of Fuel Electrode A fuel electrode was formed on the electrode reaction layer by a slurry coating method. The film thickness (after firing) was 90 μm. Furthermore, the electrode reaction layer and the fuel electrode were co-fired at 1400 ° C.

(9) Fabrication of interconnector: The composition of the interconnector is La _0.80 Ca _0.20 CrO ₃ , Ca represented by
Was obtained as a lanthanum chromite solid solution of which was prepared by spray pyrolysis and then heat-treated. The average particle size of the obtained powder was 1 μm. 40 parts by weight of the powder were used as 100 parts by weight of a solvent (ethanol), 2 parts by weight of a binder (ethyl cellulose), 1 part by weight of a dispersant (polyoxyethalene alkylsonate), and 1 part by weight of a defoaming agent (sorbitan sesquioleate). After mixing, the mixture was thoroughly 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.

Example 2 SSZ was used as the material for the electrode reaction layer, the composition was 90 mol% ZrO ₂ -10 mol% Sc ₂ O ₃ , and the firing temperature was 135.
Same as Example 1 except that the temperature was 0 ° C.

Example 3 A material for the electrode reaction layer was La _0.75 Sr.
A lanthanum manganite in which Sr represented by a composition of _0.25 MnO ₃ was dissolved was used, and the same procedure as in Example 1 was performed except that the average particle size of the raw material was 2 μm. The pore size at this time is 2 μm and the porosity is 20.
%Met.

Comparative Example 1 The same procedure as in Example 1 was carried out except that no electrode reaction layer was provided between the air electrode and the electrolyte.

(Power Generation Test) The power generation test was conducted using the cells (fuel electrode effective area: 150 cm ² ) obtained in Examples 1 to 3 and Comparative Example 1. 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: 800 ° C. Current density: 0.3Acm ^-2

[0141]

[Table 1] Table 1 shows the results of the power generation potential at a current density of 0.3 Acm ^-2 at 800 ° C. At the same current density, the higher the power generation potential, the better the output performance of the solid oxide fuel cell. table 1
As shown in (1), it can be seen that the power generation potential is higher than that of Comparative Example 1. From the above results, it was confirmed that it is preferable to provide the electrode reaction layer between the air electrode and the electrolyte.

Regarding Pore Size (Example 4) The composition of the electrode reaction layer was La _0.75 Sr _0.25 MnO ₃ /
90 mol% ZrO ₂ -10 mol% Sc ₂ O ₃ = 50/50, the average particle size of the raw material was 0.5 μm, and the film was formed on the surface of the air electrode by the slurry coating method. The same method as in Example 1 was used except that sintering was performed.

Example 5 The composition of the electrode reaction layer was La
And _{0.75 Sr 0.25 MnO 3/90 mol} % ZrO 2 -10mol% Sc 2 O 3 = 50/50, the average particle diameter of the raw material is used as consisting of 5 [mu] m, was formed by a slurry coating method on the air electrode surface After that, the same method as in Example 1 was performed except that sintering was performed at 1400 ° C.

Example 6 The composition of the electrode reaction layer was La
And _{0.75 Sr 0.25 MnO 3/90 mol} % ZrO 2 -10mol% Sc 2 O 3 = 50/50, the average particle diameter of the raw material is used as consisting of 10 [mu] m,
After forming a film on the surface of the air electrode by the slurry coating method, 1400 ℃
The same method as in Example 1 was used except that the sintering was carried out in.

Example 7 The composition of the electrode reaction layer was La
And _{0.75 Sr 0.25 MnO 3/90 mol} % ZrO 2 -10mol% Sc 2 O 3 = 50/50, the average particle diameter of the raw material by using one made of 0.2 [mu] m,
After forming a film on the air electrode surface by the slurry coating method, 1350 ℃
The same method as in Example 1 was used except that the sintering was carried out in.

Example 8 The composition of the electrode reaction layer was La
And _{0.75 Sr 0.25 MnO 3/90 mol} % ZrO 2 -10mol% Sc 2 O 3 = 50/50, the average particle diameter of the raw material is used as consisting of 15 [mu] m,
After forming a film on the surface of the air electrode by the slurry coating method, 1400 ℃
The same method as in Example 1 was used except that the sintering was carried out in.

Example 9 The composition of the electrode reaction layer was La
And _{0.75 Sr 0.25 MnO 3/90 mol} % ZrO 2 -10mol% Sc 2 O 3 = 50/50, the average particle diameter of the raw material by using one made of 0.5 [mu] m,
After forming a film on the surface of the air electrode by the slurry coating method, 1400 ℃
The same method as in Example 1 was used except that the sintering was carried out in.

(Power Generation Test) A power generation test was conducted using the cells (fuel electrode effective area: 150 cm ² ) obtained in Example 1 and Examples 4 to 9. 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: 800 ° C. Current density: 0.3 Acm ^-2 Furthermore, after the power generation test, Example 1 and Example 4 to The pore diameter of the electrode reaction layer in 9 was measured.

[0149]

[Table 2] Table 2 shows the results of the generated potential at 800 ° C and a current density of 0.3 Acm ^-2 . It can be seen that the power generation potential varies depending on the pore diameter of the electrode reaction layer, even though the same material is used. It can be seen that the power generation potential is high in Examples 1, 4 to 6 and 9, but the potential is lowered in Examples 7 and 8. However, since it is higher than that of Comparative Example 1 shown in Table 1, there is no particular problem. From the above results, it was confirmed that the pore diameter of the electrode reaction layer is more preferably about 0.1 to 10 μm, which exhibits a high power generation potential.

Porosity After the power generation test, the porosity of the electrode reaction layers in Example 1 and Examples 4 to 9 was measured.

[0151]

[Table 3] Table 3 shows the results of the power generation potential at a current density of 0.3 Acm ^-2 at 800 ° C. It can be seen that the power generation potential differs depending on the porosity of the electrode reaction layer, even though the same material is used. It can be seen that the power generation potential is high in Examples 1, 4 to 6 and 9, but the potential is lowered in Examples 7 and 8. Comparative Example 1 although the potential was lowered in Examples 7 and 8
There is no problem because it is higher than. From the above results, the porosity of the electrode reaction layer shows a high value of the generated potential 3-40.
It has been confirmed that about 10% is more preferable.

Thickness of Electrode Reaction Layer (Example 10) The composition of the electrode reaction layer was La _0.75 Sr _0.25 MnO ₃
/ 90 mol% ZrO ₂ -10 mol% Sc ₂ O ₃ = 50/50, thickness 3 μm
Same as Example 1 except that

Example 11 The composition of the electrode reaction layer was La
And _{0.75 Sr 0.25 MnO 3/90 mol} % ZrO 2 -10mol% Sc 2 O 3 = 50/50, except that the thickness of 5μm were the same as in Example 1.

Example 12 The composition of the electrode reaction layer was La
And _{0.75 Sr 0.25 MnO 3/90 mol} % ZrO 2 -10mol% Sc 2 O 3 = 50/50, except that the thickness of 30μm were the same as in Example 1.

Example 13 The composition of the electrode reaction layer was La
And _{0.75 Sr 0.25 MnO 3/90 mol} % ZrO 2 -10mol% Sc 2 O 3 = 50/50, except that the thickness of 50μm were the same as in Example 1.

Example 14 The composition of the electrode reaction layer was La
And _{0.75 Sr 0.25 MnO 3/90 mol} % ZrO 2 -10mol% Sc 2 O 3 = 50/50, except that the thickness of 2μm were the same as in Example 1.

Example 15 The composition of the electrode reaction layer was La
And _{0.75 Sr 0.25 MnO 3/90 mol} % ZrO 2 -10mol% Sc 2 O 3 = 50/50, except that the thickness of 55μm were the same as in Example 1.

(Power Generation Test) A power generation test was performed using the cells (fuel electrode effective area: 150 cm ² ) obtained in Example 1 and Examples 10 to 15. 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: 800 ° C. Current density: 0.3Acm ^-2

[0159]

[Table 4] Table 4 shows the results of the generated potential at a current density of 0.3 Acm ^-2 at 800 ° C. It can be seen that the power generation potential differs depending on the thickness of the electrode reaction layer, even though the same material is used. It can be seen that the power generation potential is high in Examples 1 and 10 to 13, but the potential is lowered in Examples 14 and 15.
In Examples 14 and 15 as well, although the potential was lowered, it was higher than that in Comparative Example 1, so there was no problem. From the above results, the thickness of the electrode reaction layer shows a high value of the generated potential 3-5.
It was confirmed that about 0 μm is preferable. Further examples
Since the output performance of Examples 1, 11 and 12 is higher when compared with 1 and 10 to 13, the thickness of the electrode reaction layer is 5 to 30 μm.
Was confirmed to be more preferable.

Electrode Reaction Layer Material (Example 16) Example 1 except that the material for the electrode reaction layer was cerium oxide and the composition was (CeO ₂ ) _0.8 (Sm ₂ O ₃ ) _0.1.
Same as.

Example 17 The material of the electrode reaction layer was SSZ / cerium.
Oxide of 90 mol% ZrO₂-10mol% Sc ₂O₃/ (C
eO₂)_0.8(Sm₂O₃)_0.1Same as Example 1 except = 50/50
I chose

[0162] (Example 18) electrode reaction layer material, a lanthanum manganite / cerium oxide, the composition La _{0.7 5} Sr
Except for using _{0.25 MnO 3 / (CeO 2)} 0.8 (Sm 2 O 3) 0.1 = 50/50 were the same as in Example 1.

Example 19 An electrode reaction layer material was lanthanum.
Nganite / SSZ / Cerium oxide_0.75S
r_0.25MnO₃/ 90mol% ZrO₂-10mol% Sc₂O₃ / (CeO₂)_0.8(Sm₂O
₃)_0.1= 50/25/25. La as a raw material synthesis method_0.75Sr
_0.25MnO₃/ 90mol% ZrO₂-10mol% Sc₂O₃And La_{0 .75}Sr_0.25MnO
₃/ (CeO₂)_0.8(Sm₂O₃)_0.1Powders produced by the coprecipitation method
In addition, La _0.75Sr_0.25MnO₃/ 90mol% ZrO₂-10mol% Sc₂O₃ 
/ (CeO₂)_0.8(Sm₂O₃)_0.1= 50/25/25 mixed heat
Processed. Except for these, the same procedure as in Example 1 was performed.

Example 20 The electrode reaction layer material was YSZ,
Example 1 except that the composition was 92 mol% ZrO ₂ -8 mol% Y ₂ O _3.
Same as.

[0165] (Example 21) electrode reaction layer material, a lanthanum manganite / YSZ, the composition La _0.75 Sr _0.25 MnO ₃ / 92mol
Same as Example 1 except that% ZrO ₂ -8 mol% Y ₂ O ₃ = 50/50.

(Power Generation Test) Using the test cells of Examples 1, 2, 16 to 21 and Comparative Example 1 (fuel electrode effective area: 150 cm ² ), the following power generation test was conducted. 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: 700 to 1000 ° C. Current density: 0.3 Acm ^-2

FIG. 3 shows the result of the power generation potential at the power generation temperature. It can be seen that in Examples 1, 18, and 19, a high potential is exhibited at 700 to 1000 ° C. It can be seen that in Examples 2, 16 and 17, the potential was comparatively high up to 700 ° C., though inferior to Examples 1, 18 and 19. Examples 20, 21
Shows a high potential at 900-1000 ℃, but 9
It can be seen that the potential drop increases at temperatures below 00 ° C. On the other hand, in Comparative Example 1, even at 1000 ° C., it is lower than that of the Example, and it is understood that the potential decrease further increases as the power generation temperature decreases. From the above results, it was confirmed that the power generation potentials were higher than those of Comparative Example 1 and were preferable. When the electrode reaction layer is YSZ and lanthanum manganite / YSZ, it has a high output performance at 900 to 1000 ° C, and when the electrode reaction layer is SSZ, cerium oxide, and SSZ / cerium oxide, even at 900 ° C or less. It has been found that it has a high output performance and is preferable. Furthermore, the electrode reaction layer is lanthanum manganite / SSZ, lanthanum manganite /
It was confirmed that cerium oxide and lanthanum manganite / SSZ / cerium oxide are more preferable because they have excellent output performance even at about 700 ° C.

Regarding the solid solution amount of scandia in the electrode reaction layer (Example 22) The composition of the electrode reaction layer and the weight ratio thereof were set to La
Except that the _{0.75 Sr 0.25 MnO 3/97 mol} % ZrO 2 -3mol% Sc 2 O 3 = 50/50 were the same as in Example 1.

[0169] (Example 23) the composition and the weight ratio of the electrode reaction layers _{La 0.75 Sr 0.25 MnO 3/92} mol% ZrO 2 -8mol% Sc 2 O 3
Same as Example 1 except that = 50/50.

[0170] La _0.75 The composition and the weight ratio of (Example 24) electrode reaction layer _{Sr 0.25 MnO 3/88 mol%} ZrO 2 -12mol% Sc 2 O
Same as Example 1 except that ₃ = 50/50.

[0171] (Example 25) the composition and the weight ratio of the electrode reaction layers _{La 0.75 Sr 0.25 MnO 3/98} mol% ZrO 2 -2mol% Sc 2 O 3
Same as Example 1 except that = 50/50.

[0172] La _0.75 The composition and the weight ratio of (Example 26) electrode reaction layer _{Sr 0.25 MnO 3/85 mol%} ZrO 2 -15mol% Sc 2 O
Same as Example 1 except that ₃ = 50/50.

Regarding the batteries of Example 1 and Examples 22 to 26,
A power generation test was conducted under the power generation conditions shown below. Fuel: (H ₂ + 11% H ₂ O): N ₂ = 1: 2 Oxidizing agent: Air Power generation temperature: 800 ° C. Current density: 0.3Acm ^-2

[0174]

[Table 5]

Table 5 shows the results of the power generation potential at 800 ° C. and a current density of 0.3 Acm ⁻² . It can be seen that in Examples 1 and 22 to 24, the potential is high, whereas in Examples 25 and 26, the potential is lowered. However, even in Examples 25 and 26, the potential was much higher than that of Comparative Example 1 shown in Table 1, and therefore it was found that there is no problem if it is reduced to this extent. Since the potential is high, SS in the electrode reaction layer
It was confirmed that the solid solution amount of scandia in Z is preferably in the range of 3 to 12 mol%. In addition, Example 1, Examples 22-2
When the data of Example 4 are compared, the potential of Example 22 is lower than the others, so that the amount of scandia solid solution is 8 to 12 mol.
It has been confirmed that it is more preferable if it is%.

Effect of CeO _{2 and the} like on SSZ (Example 27) The composition of the electrode reaction layer and its weight ratio were changed to La
_0.75 Sr _0.25 MnO ₃ / 88mol% ZrO ₂ -10mol% Sc ₂ O ₃ -2mol% CeO ₂
Same as Example 1 except that = 50/50.

[0177] (Example 28) the composition and the weight ratio of the electrode reaction layers _{La 0.75 Sr 0.25 MnO 3 / 85mol} % ZrO 2 -10mol% Sc 2 O 3 -
Same as Example 1 except that 5 mol% CeO ₂ = 50/50.

[0178] (Example 29) the composition and the weight ratio of the electrode reaction layers _{La 0.75 Sr 0.25 MnO 3 / 84mol} % ZrO 2 -10mol% Sc 2 O 3 -
Same as Example 1 except that 6 mol% CeO ₂ = 50/50.

Example 30 The composition of the electrode reaction layer and the weight ratio thereof were changed to La _0.75 Sr _0.25 MnO ₃ / 88mol% ZrO ₂ -10mol% Sc ₂ O _3-.
Same as Example 1 except that ₂ mol% Bi ₂ O ₃ = 50/50.

Example 31 The composition of the electrode reaction layer and the weight ratio thereof were changed to La _0.75 Sr _0.25 MnO ₃ / 88mol% ZrO ₂ -10mol% Sc ₂ O _3-.
Same as Example 1 except that ₂ mol% Y ₂ O ₃ = 50/50.

Example 32 The composition of the electrode reaction layer and the weight ratio thereof were changed to La _0.75 Sr _0.25 MnO ₃ / 88mol% ZrO ₂ -10mol% Sc ₂ O _3-.
Example 1 except that 1 mol% Y CeO ₂ -1 mol% Bi ₂ O ₃ = 50/50
Same as.

Regarding the batteries of Example 1 and Examples 27 to 32,
A power generation test was conducted under the power generation conditions shown below. Fuel: (H ₂ + 11% H ₂ O): N ₂ = 1: 2 Oxidizing agent: Air Power generation temperature: 800 ° C. Current density: 0.3Acm ^-2

[0183]

[Table 6] Table 6 shows the results of the generated potential at a current density of 0.3 Acm ^-2 at 800 ° C. Comparing Example 1 and Examples 27-29, Example 2
7. In Example 28, the potential increased, but in Example 29, it tended to decrease. It was confirmed that in Examples 30 and 31, the sinterability of the electrode reaction layer material was improved although the potential was the same as that in Example 1. In Example 32, it was confirmed that the potential was increased and the sinterability of the electrode reaction layer material was improved. From the above results, 5% of CeO ₂ was added to SSZ.
It was confirmed that the solid-solution not more than mol% improves the output performance, and it was found to be preferable. Further, it was found that solid solution of Y ₂ O ₃ or Bi ₂ O ₃ improves the sinterability, which is preferable. Other rare earth oxides such as Gd ₂ O ₃ and Yb ₂ O ₃
It was thought that it is preferable because it can be easily inferred that either the output performance or the sinterability is improved even when the solid solution is less than mol%.

Regarding (CeO ₂ ) _1-2x (Sm ₂ O ₃ ) _x (Example 33) The electrode reaction layer material was lanthanum manganite /
Cerium oxide, the composition of which is La _{0.7 5} Sr _0.25 MnO ₃ / (CeO
₂ ) _0.9 (Sm ₂ O ₃ ) _0.05 = 50/50 The procedure was the same as in Example 1.

[0185] (Example 34) electrode reaction layer material, a lanthanum manganite / cerium oxide, the composition La _{0.7 5} Sr
Same as Example 1 except that _0.25 MnO ₃ / (CeO ₂ ) _0.7 (Sm ₂ O ₃ ) _0.15 = 50/50.

[0186] (Example 35) electrode reaction layer material, a lanthanum manganite / cerium oxide, the composition La _{0.7 5} Sr
Same as Example 1 except that _0.25 MnO ₃ / (CeO ₂ ) _0.75 (Sm ₂ O ₃ ) _0.025 = 50/50.

[0187] (Example 36) electrode reaction layer material, a lanthanum manganite / cerium oxide, the composition La _{0.7 5} Sr
_Same as Example 1 except that _0.25 MnO ₃ / (CeO ₂ ) _0.65 (Sm ₂ O ₃ ) _0.175 = 50/50.

Regarding the batteries of Example 18 and Examples 33 to 36,
A power generation test was conducted under the power generation conditions shown below. Fuel: (H ₂ + 11% H ₂ O): N ₂ = 1: 2 Oxidizing agent: Air Power generation temperature: 800 ° C. Current density: 0.3Acm ^-2

[0189]

[Table 7] Table 7 shows the results of the power generation potential at a current density of 0.3 Acm ^-2 at 800 ° C. Comparing Example 18 and Examples 33-36, Example 3
5. It can be seen that the potential is somewhat lower at the x value of Example 36. From the above results, it was confirmed that the range of 0.05 ≦ x ≦ 0.15 is more preferable for (CeO ₂ ) _1-2x (Sm ₂ O ₃ ) _x . Although only Sm is used in this embodiment, Gd and Y
It was considered to be preferable because the above can be easily estimated to have the same effect.

Regarding the composition of lanthanum manganite in the electrode reaction layer (Example 37) The composition of the electrode reaction layer and its weight ratio were La.
Except that the _{0.75 Ca 0.25 MnO 3 / 90mol%} ZrO 2 -10mol% Sc 2 O 3 = 50/50 were the same as in Example 1.

The batteries of Examples 1 and 37 were subjected to a power generation test under the power generation conditions shown below. Fuel: (H ₂ + 11% H ₂ O): N ₂ = 1: 2 Oxidizing agent: Air Power generation temperature: 800 ° C. Current density: 0.3Acm ^-2

[0192]

[Table 8] Table 8 shows the results of the generated potential at 800 ° C and a current density of 0.3 Acm ^-2 . It was confirmed that the lanthanum manganite in the electrode reaction layer may be either lanthanum manganite in which Ca or Sr is formed as a solid solution, since the potentials in Example 1 and Example 31 hardly change.

Regarding Electrolyte Material (Example 38) The electrolyte material was YSZ, and the composition was 92 mol% ZrO 2.
Same as Example 1 except that it was ₂ -8 mol% Y ₂ O ₃ .

Using the test cells of Examples 1 and 38 and Comparative Example 1 (fuel electrode effective area: 150 cm ² ), the following power generation test was conducted. 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: 700 to 1000 ° C. Current density: 0.3 Acm ^-2

FIG. 4 shows the result of the power generation potential at the power generation temperature. In Example 38, the potential is almost the same at 1000 ° C., but the potential decreases at 900 ° C. or less, and it is understood that the potential difference is considerably large at about 700 ° C. as in Example 1. However, it can be seen that there is a large difference from Comparative Example 1. From the above results, it was confirmed that SSZ is preferable as the electrolyte at the power generation temperature of 900 ° C. or lower, but it is almost the same at 900 ° C. or higher, and it is confirmed that there is no problem even if the electrolyte is YSZ.

By interposing the electrode reaction layer shown in Example 1 and Example 19 and Example 27, it is possible to provide a solid oxide fuel cell having a high potential of 0.6 V or more even at a low temperature of about 700 ° C. It was

[0197]

EFFECTS OF THE INVENTION As is clear from the above description, by providing an electrode reaction layer containing a catalyst for ionizing oxygen gas between an air electrode and an electrolyte and having open pores communicating with each other, a solid body having excellent output performance An electrolyte fuel cell 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.

[Figure 3] Power generation temperature (horizontal axis) and power generation potential of test battery (vertical axis)
It is a graph which shows the relationship of.

[Figure 4] Power generation temperature (horizontal axis) and power generation potential of test battery (vertical axis)
It is a graph which shows the relationship of.

[Explanation of symbols]

1: Air electrode support 2: Interconnector 3: Electrolyte 4: Fuel electrode 5: Electrode reaction layer 6: Fuel side electrode reaction layer

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 1, 2002 (2002.11.
1)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0135

[Correction method] Change

[Correction content]

(8) Preparation of Fuel Electrode A fuel electrode was formed on the fuel side electrode reaction layer by a slurry coating method. The film thickness (after firing) was 90 μm. In addition, burn
The material side electrode reaction layer and the fuel electrode were co-fired at 1400 ° C.

Continued front page    F-term (reference) 5H018 AA06 AS01 BB01 BB06 BB08                       BB12 BB16 EE12 HH03 HH04                       HH05 HH06 HH08                 5H026 AA06 BB08 CC06 CV02 EE13                       HH04 HH05 HH06 HH08

Claims (20)

[Claims] 1. An air electrode, an electrolyte, and a fuel electrode are provided,
A solid oxide fuel cell in which an electrode reaction layer is interposed between the air electrode and the electrolyte, wherein the electrode reaction layer contains at least a catalyst for ionizing oxygen gas and has open pores communicating with each other. A characteristic solid oxide fuel cell. 2. The pore size of the electrode reaction layer is 0.1 to 1
The solid oxide fuel cell according to claim 1, wherein the solid oxide fuel cell has a thickness of 0 μm. 3. The solid oxide fuel cell according to claim 1, wherein the electrode reaction layer has a pore size smaller than that of the air electrode. 4. The porosity of the electrode reaction layer is 3 to 40.
%, And the solid oxide fuel cell according to any one of claims 1 to 3. 5. The solid oxide fuel cell according to claim 1, wherein a porosity of the electrode reaction layer is equal to or lower than a porosity of the air electrode. 6. The thickness of the electrode reaction layer is 3 to 50 μm.
The solid oxide fuel cell according to any one of claims 1 to 5, wherein m is m. 7. The thickness of the electrode reaction layer is 5 to 30 μm.
7. The solid oxide fuel cell according to claim 6, wherein m is m. 8. The thickness of the electrode reaction layer is smaller than the thickness of the air electrode.
The solid oxide fuel cell according to any one of items 1 to 7. 9. The group of the electrode reaction layer comprising a scandia solid solution zirconia layer, a cerium oxide layer, and a scandia solid solution zirconia and cerium oxide layer uniformly mixed in a predetermined weight ratio. 9. The solid oxide fuel cell according to claim 1, wherein the solid oxide fuel cell is any one of the above. 10. The solid according to claim 1, wherein the electrode reaction layer further contains a material having an electronic conductivity of 10 Scm ⁻¹ or more at 1000 ° C. Electrolyte fuel cell. 11. The electrode reaction layer is a layer in which lanthanum manganite and zirconia in which scandia is dissolved are uniformly mixed in a predetermined weight ratio, and lanthanum manganite and cerium oxide are uniformly mixed in a predetermined weight ratio. It is characterized by being a mixture of any one of the group consisting of a mixed layer, a layer in which zirconia and cerium oxide in which lanthanum manganite and scandia are dissolved in solid solution are uniformly mixed in a predetermined weight ratio. The solid oxide fuel cell according to any one of claims 1 to 8 and 10. 12. The solid oxide fuel cell according to claim 9, wherein the scandia solid solution contains zirconia in a solid solution amount of 3 to 12 mol%. . 13. The zirconia in which scandia is solid-dissolved further comprises one or two of rare earth oxides such as CeO ₂ , Gd ₂ O ₃ , Y ₂ O ₃ and Yb ₂ O ₃ and Bi ₂ O _3. The solid oxide fuel cell according to any one of claims 9 to 12, wherein the above oxides are solid-dissolved, and the oxide is dissolved in a total amount of 5 mol% or less. 14. The lanthanum manganite in the electrode reaction layer is LaAMnO ₃ (where A = Ca or Sr).
12. The solid oxide fuel cell according to claim 11, which is made of lanthanum manganite represented by 15. The cerium oxide in the electrode reaction layer is represented by the general formula (CeO ₂ ) _1-2X (B ₂ O ₃ ) _{X / 2} (wherein one of B = Sm, Gd and Y, 0.05 ≦ X ≦ 0.15), The solid oxide fuel cell according to claim 9 or 11. 16. The solid oxide fuel cell according to claim 1, wherein the electrolyte is zirconia in which yttria or scandia is dissolved. 17. The lanthanum manganite represented by LaAMnO ₃ (wherein A = Ca or Sr), wherein the air electrode is lanthanum manganite. Solid oxide fuel cell. 18. The fuel electrode according to claim 1, wherein the fuel electrode is composed of a layer in which NiO and yttria are dissolved in zirconia uniformly in a predetermined weight ratio. Solid oxide fuel cell. 19. A Ni electrode is provided between the fuel electrode and the electrolyte.
The fuel side electrode reaction layer comprising a layer in which zirconia in which O and scandia are dissolved as a solid solution is uniformly mixed in a predetermined weight ratio is interposed. Solid oxide fuel cell. 20. The solid oxide fuel cell according to claim 1, wherein the interconnector in the solid oxide fuel cell is lanthanum chromite containing Ca as a solid solution.