JPH07296839A - Solid electrolyte fuel cell - Google Patents

Abstract

PURPOSE:To enhance the creep resistance of a sling tube to enhance the nondefective ratio of the tube during manufacture and to enhance the long-range stability of a cell during power generation by forming the sling tube out of a complex perovskite oxide having a specific composition. CONSTITUTION:A solid electrolyte fuel cell comprises a solid electrolyte 2 and a fuel electrode 3 stacked sequentially on a porous sling tube 1 having the function of an air electrode. The sling tube 1 as made of a complex perovskite oxide having a composition represented by formula I: A is at least one kind selected from Y and a group of rare earth elements; B is at least one kind selected from the group of Ca, Ba and Sr; C is at least one kind selected from the group of Co, Ni, Zr,Ce, Fe and Mg; and (x), (y), (z) and (p) meet: 0.05<=x<=0.3; 0.25<=y<=0.5; 0.9<=z<=1.05; and 0<=p<=0.3. The oxide contains metal impurities other than the above constituent elements, the Al and Si contents of the oxide being 0.2wt.% or less, and the content of metal impurities being 0.8wt.% or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid oxide fuel cell, and more particularly to improvement of a porous support tube having air electrode capability.

[0002]

2. Description of the Related Art Conventionally, two types of fuel cells, a cylindrical type and a flat type, have been known as solid oxide fuel cell units. The flat plate type fuel cell has a characteristic that the output density per unit volume of power generation is high, but when it is put into practical use, there are problems such as incomplete gas sealing and uneven temperature distribution in the cell. On the other hand, in the cylindrical fuel cell,
Although the power density is low, it has the advantages that the mechanical strength of the cell is high and that the temperature distribution inside the cell is uniform.
Both types of solid electrolyte fuel cells are being actively researched and developed by taking advantage of their respective characteristics.

Generally, a single cell of a cylindrical fuel cell is shown in FIG.
As shown in Figure 5, CaO-stabilized Z with open porosity of about 40%
For example, a porous air electrode 12 made of LaMnO ₃ material is formed on the surface of the support tube 11 made of rO ₂ by a slurry dipping method, and a vapor phase synthesis method (EVD) is made on the surface.
Alternatively, a stabilized ZrO ₂ solid electrolyte 13 containing Y ₂ O ₃ is formed by a method such as a thermal spraying method, and a fuel electrode 14 made of porous Ni-zirconia or the like is formed on the surface of the solid electrolyte 13. . The fuel cell module is
A plurality of unit cells having the above structure are connected via an interconnector 15 made of LaCrO ₃ based material or the like.
Power generation is performed at a temperature of 1000 to 1050 ° C. by flowing air (oxygen) inside the support tube 11 and flowing fuel (hydrogen) outside.

In recent years, in producing the above fuel cell,
In order to simplify the process, the air electrode LaMnO ₃
Attempts have been made to use the system material directly as a porous support tube. As a supporting tube material that also has a function as an air electrode, for example, a LaMnO ₃ solid solution material in which La is replaced with 10 to 20 atomic% of Ca or Sr is used.

[0005]

However, when the above-mentioned LaMnO ₃ material in which CaO or SrO is solid-solved is used as a support tube, a vapor phase synthesis method (EV
When the solid electrolyte membrane or the interconnector is coated by D) or the thermal spraying method, the support tube is kept at a high temperature of 1000 ° C. or higher, particularly 1200 ° C. to 1400 ° C. in the vapor phase synthesis method. For this reason, there has been a problem that the supporting tube creeps and deforms during the formation of the solid electrolyte membrane or the interconnector membrane, and the cells cannot be connected. Further, also in power generation, since the cells are held at a high temperature of 1000 ° C. for a long time, similarly, the support tube is deformed, the connection between the cells is deteriorated, and the output is reduced.

The present invention improves the creep resistance of the support tube having the air electrode function, solves the problem of the deformation of the support tube during the cell manufacturing process or during power generation, improves the yield rate of the cell, and improves the high temperature. The purpose of the present invention is to provide a cell having long-term stability even if it is held at.

[0007]

Means for Solving the Problems As a result of repeated studies to solve the above-mentioned problems, the present inventors formed a LaMnO ₃ -based material as a support tube, and formed a part of La in the LaMnO ₃ -based material. Is replaced by a specific trivalent metal at the same time as a predetermined alkaline earth element, and in some cases, a part of Mn is replaced by another transition metal element, and at the same time, the amount of metal impurities is controlled to be a predetermined amount or less. It has been found that the above object can be achieved by substituting a part of Mn in the above system with Cr together with a transition metal in a specific ratio.

That is, the solid oxide fuel cell of the present invention is a solid oxide fuel cell in which a solid electrolyte and a fuel electrode are sequentially laminated on a porous support tube having an air electrode capability. The tube is

[0009]

[Chemical 1]

In the formula, A is at least one selected from the group consisting of Y and rare earth elements, and B is Ca and Ba.
And at least one selected from the group of Sr, C is Co,
At least one selected from the group consisting of Ni, Zr, Ce, Fe and Mg, and x, y, z and p
, 0.05 ≦ x ≦ 0.3, 0.25 ≦ y ≦ 0.5,
It is composed of a complex perovskite type oxide satisfying 0.9 ≦ z ≦ 1.05 and 0 ≦ p ≦ 0.3, and Al and Si in the total amount of metal impurities other than the constituent elements are 0.
2% by weight or less, and the total amount of metal impurities is 0.8% by weight or less.

Further, in a solid oxide fuel cell in which a solid electrolyte and a fuel electrode are sequentially laminated on a porous support tube having an air electrode capability, the support tube has the following chemical formula 2.

[0012]

[Chemical 2]

In the formula, A is at least one selected from the group consisting of Y and rare earth elements, and B is Ca and Ba.
And at least one selected from the group of Sr, C is C
and at least one selected from the group consisting of o, Ni, Zr, Ce, Fe, and Mg, and a, b, c, d, and e are 0.02 ≦ a ≦ 0.50, 0.20 ≦ b ≦
0.60, 0.90 ≦ c ≦ 1.05, 0 ≦ d ≦ 0.40
And a complex perovskite type oxide satisfying 0.02 ≦ e ≦ 0.50.

The present invention will be described in detail below. FIG. 1 is a diagram for explaining one embodiment of a solid oxide fuel cell unit according to the present invention. In FIG. 1, 1 is a support tube, 2 is a solid electrolyte, and 3 is a fuel electrode.

According to the present invention, the support tube 1 itself has a cylindrical shape made of conductive ceramics. A solid electrolyte 2 is formed on the cylindrical support tube 1, and a fuel electrode 3 is further formed on the solid electrolyte 2. When power is generated by the cell having such a structure, a gas containing oxygen such as air is supplied to the inside of the cylindrical support tube 1, while a fuel gas such as hydrogen gas is supplied to the fuel electrode 3 side. Electric power is generated between the support tube 1 and the fuel electrode 3. Therefore, the support tube 1 and the fuel electrode 3 are each made of a porous body having an open porosity of 35 to 40% so that the supplied gas can be supplied to the solid electrolyte. Further, the fuel cell module is configured by connecting a plurality of cells via the interconnector 4.

According to the first aspect of the present invention, in the above-mentioned structure, the support tube 1 has the following structure.

[0017]

[Chemical 1]

In the formula, A is at least one selected from the group consisting of Y and rare earth elements, and B is Ca and Ba.
And at least one selected from the group of Sr, C is Co,
At least one element selected from the group consisting of Ni, Zr, Ce, Fe and Mg
Where x, y, z and p are 0.05 ≦ x ≦ 0.3,
0.25 ≦ y ≦ 0.5, 0.9 ≦ z ≦ 1.05 and 0
A major feature is that the material is made of a material that satisfies ≦ p ≦ 0.3. Further, such a material is composed of a complex perovskite type oxide.

In the present invention, the composition of the supporting tube material is limited to the above range by adding Y to Y, Yb,
If the x value indicating the substitution amount of Sc, Er, etc. is smaller than 0.05 or larger than 0.3, the creep deformation amount becomes large, and the y value showing the substitution amount of Ca, Sr, Ba for La. Of less than 0.25, the amount of creep deformation increases, and when the y value is greater than 0.5, the firing temperature is 1600.
It is necessary to raise the temperature to not less than 0 ° C, which is not economical, and calcination at low temperature deteriorates the sinterability, making it difficult to produce a material having a predetermined open porosity.

The z value showing the ratio of A site to B site is usually 1 in the perovskite type crystal structure, but the same effect can be obtained even if the z value is a nonstoichiometric ratio up to 0.9. However, if it is smaller than 0.9, a different phase containing Mn or the like other than the perovskite type is precipitated and the creep deformation amount increases. On the other hand, when this value exceeds 1.05, La ₂ O ₃ precipitates and the material weathers in a short time.

Further, even if Mn is replaced with Co, Ni, Zr, Ce, Fe or the like on the basis of the LaMnO ₃ type solid solution, the lattice defect structure does not substantially change. However, when the substitution amount p value exceeds 0.3 due to these elements, the creep deformation amount increases.

In the present invention, the particularly desirable range in the composition system of the above chemical formula 1 is 0.05 ≦ x ≦ 0.2, 0.2.
5 ≦ y ≦ 0.4, 0.95 ≦ z ≦ 1.0, 0 ≦ p ≦ 0.
It is 2.

Further, in the system represented by the above chemical formula 1, the amount of metal impurities contained in the material constituting the support tube is 0.8% by weight or less, and Al and Si therein.
It is important that the total amount is 0.2% by weight or less. The metal impurities in the present invention include Al, Si, Ti,
Nb, Na, V, etc. are treated as impurities. The amount of these metal impurities exceeds 0.8% by weight,
Alternatively, when the amount of Al and Si exceeds 0.2% by weight, the amount of creep deformation increases. According to the present invention, it is particularly preferable that the amounts of Al and Si are controlled to 0.1% by weight or less and the total amount of the metal impurities is controlled to 0.5% by weight or less.

Furthermore, according to the present invention, the support tube is
The following formula 2

[0025]

[Chemical 2]

In the formula, A is at least one member selected from the group consisting of Y and rare earth elements, and B is Ca and Ba.
And at least one selected from the group of Sr, C is C
and at least one selected from the group consisting of o, Ni, Zr, Ce, Fe, and Mg, and a, b, c, d, and e are 0.02 ≦ a ≦ 0.50, 0.20 ≦ b ≦
0.60, 0.90 ≦ c ≦ 1.05, 0 ≦ d ≦ 0.40
By using a composite perovskite type oxide satisfying the above condition and 0.02 ≦ e ≦ 0.50, the same effect can be obtained.

In the complex perovskite type oxide having the composition of Chemical formula 2, the composition is limited to the above range because the substitution amount a value of Y or rare earth element to La is smaller than 0.02, or If it is larger than 0.50, the amount of creep deformation becomes large, and even if the amount b of Ca, Sr, or Ba replaced by La is smaller than 0.20, the amount of creep deformation becomes large and the value b becomes large. If it is larger than 0.6, the firing temperature is 160
It is necessary to raise the temperature to 0 ° C. or higher, which is not economical, and calcination at low temperature deteriorates sinterability, making it difficult to produce a material having a predetermined open porosity.

The c value showing the ratio of A site to B site is usually 1 in the perovskite type crystal structure, but the same effect can be obtained even if the z value is a nonstoichiometric ratio up to 0.9. However, if it is smaller than 0.9, a different phase containing Mn or the like other than the perovskite type is precipitated and the creep deformation amount increases. On the other hand, when this value exceeds 1.05, La ₂ O ₃ precipitates and the material weathers in a short time.

Further, when the substitution amount d of Mn such as Co, Ni, Zr, Ce, and Fe exceeds 0.40, the creep deformation amount becomes large. Further, when the substitution amount e of Mn for Cr is smaller than 0.02, the creep deformation amount is large,
When it is larger than 0, the sinterability is deteriorated and it becomes difficult to produce a material having a predetermined open porosity.

In the present invention, the particularly desirable range in the composition system of Chemical Formula 2 is 0.05 ≦ a ≦ 0.20,0.
20 ≦ b ≦ 0.40, 0.95 ≦ c ≦ 1.0, 0 ≦ d ≦
0.3 and 0.05 ≦ e ≦ 0.2 are preferable.

The solid electrolyte used in the fuel cell of the present invention is made of well-known stabilized ZrO ₂ containing a stabilizer such as Y ₂ O ₃ or CaO, and Ni-zirconia or the like is used as the fuel electrode material. Moreover, the interconnector is LaCrO ₃ system, and a part of La is Ca.
A complex oxide substituted with an alkaline earth such as is used.

According to the present invention, even when the air electrode is used as the gas diffuser in the flat plate type fuel cell, the deformation at high temperature is small, so that the connection with the electrolyte is excellent and, as a result, the power generation output due to the connection failure. The decrease can be suppressed.

[0033]

The perovskite type crystal is generally represented by ABO ₃ , and the lattice points in the crystal are divided into three sites, A site, B site and oxygen (O) site. LaMnO ₃ , L
From the detailed results of the study on the lattice defect structure in the material in which CaO or SrO was dissolved in aFeO ₃ or LaCoO ₃ system, the substitution of Ca or Sr for La was found in these materials regardless of the degree of A site defect. If the amount is less than 25 atom%, the following formula 1

[0034]

[Equation 1]

By the reaction of (3), cation vacancies of La and Mn are predominantly produced.

On the other hand, when the substitution amount is 25 atomic% or more, the following formula 2

[0037]

[Equation 2]

It was clarified that the oxygen ion vacancies became dominant by the reaction of.

These results mean that the solid solution has a large diffusion rate of cations through cation vacancies when the substitution amount of Ca or Sr is less than 25 atom%.

Regarding creep deformation, when the deformation occurs due to diffusion and intraparticle (volume) diffusion is dominant, the creep deformation rate is expressed by the following equation 3.

[0041]

[Equation 3]

It is represented by

If grain boundary diffusion is dominant, the following equation 4

[0044]

[Equation 4]

It is expressed as follows.

Generally, DV and Db are the diffusion coefficients of the slower ion of the anion and the cation in the crystal.
In the perovskite type crystal, the diffusion coefficient in equations 1 and 2 is that of cations. According to these equations, it is easily judged that the creep resistance is better as the diffusion coefficient is smaller and the particles are larger.

The substitution ratio (y value) of Ca, Ba and Sr is 2
Considering the above-mentioned lattice defect structure, the reason why the amount of deformation due to creep is large when the content is less than 5 atomic% is that the concentration of cation vacancies generated by Equation 1 is high, so It is considered that the diffusion rate was high, and as a result, the creep deformation rate was high. Also, Y,
Regarding the effect of adding rare earth elements such as Yb, when the addition amount (x value) of the rare earth element is less than 5 atomic% or more than 30 atomic%, the ionic radii of the rare earth ion and the La ion are different. It is considered that a large crystal lattice distortion occurs in the material, the activation energy for cation diffusion decreases, the diffusion coefficient increases, and as a result, the creep deformation rate increases. Similar results are obtained in the non-stoichiometric system lacking the A site because there is essentially no change in the lattice defect structure as compared with the stoichiometric system.

Regarding the amount of impurities in the material, a very small amount is solid-soluted in the crystal, but if it is present in excess of the solid-solution limit, they segregate at the grain boundaries or form a glass phase at the grain boundaries. Form. When such grain boundaries exist, slippage occurs between the grains and the creep rate increases. It is speculated that the creep deformation amount increases when the amount of metal impurities exceeds 0.8% by weight due to the slip between the grain boundaries. In particular, among metal impurities, A
Since 1 and Si easily form a glass phase, it is necessary to control the amount of these in a particularly small range.

Further, even if Mn at the B site is replaced with Ni, Co or the like, it has the same lattice defect structure as LaMnO _3. Therefore, the mechanism of creep deformation is the same as that of LaMnO _{3 in} such a replacement system. However, LaN
The sintering rate of the solid solution system of iO ₃ and LaCoO ₃ is LaMnO.
₃ as compared with that in the early trend. This means La
This means that the cation diffusion coefficient in the solid solution system of NiO ₃ or LaCoO ₃ is larger than that of LaMnO ₃ . Therefore, it is considered that when the substitution amount (p value) of Mn by Ni, Co, etc. exceeds 0.3, the diffusion rate of cations increases due to the addition of Ni or Co and the creep rate increases.

As is clear from the above description, according to the constitution of the present invention, by limiting the x, y, z and p values in the composition system shown in Chemical formula 1 to the above specific ranges, Excellent creep resistance is achieved even when held at high temperatures.

Further, regarding the composition system represented by the chemical formula 2 of the present invention, even if Mn is replaced by Cr, it has the same lattice defect structure as the LaMnO ₃ system. Generally, LaCrO ₃
Is a material used as an interconnector of a fuel cell. Usually, LaCrO ₃ is a material that is difficult to sinter, so
In order to obtain a sintered body, it is necessary to fire at a high temperature near 2000 ° C. in a reducing atmosphere. This means that the cation diffusion coefficient in the LaCrO ₃ solid solution system is smaller than that of LaMnO ₃ . Therefore, Mn of B site
When Cr is replaced by Cr, if the replacement amount (e value) is 0.02 or more, the cation diffusion coefficient becomes small by the addition of Cr, and thus the creep rate is considered to become small.

Furthermore, Mn at the B site is replaced with Ce, Ni, C
Since it has the same lattice defect structure as LaMnO ₃ even when it is substituted with o, Zr, Mg, or in a non-stoichiometric system in which the A site / B site ratio in the perovskite structure is slightly deviated from 1, the mechanism of creep deformation is Is LaM
It is the same as the nO ₃ system.

For the above reason, in the chemical formula 2, a, b,
Creep resistance can be improved by limiting c, d and e to a specific ratio.

According to the present invention, when the solid electrolyte and the fuel electrode are formed on the support tubes made of the materials shown in Chemical formulas 1 and 2, the support tubes must undergo creep deformation during the formation process. Therefore, the solid electrolyte and the fuel electrode membrane are not peeled off, and excellent durability can be imparted even during long-term operation at high temperature as a fuel cell.

[0055]

EXAMPLES Next, the present invention will be explained based on examples. Example 1 Commercially available Y ₂ O ₃ , La ₂ O ₃ , and Yb _{2 having} a purity of 99.9%.
O ₃ , Sc ₂ O ₃ , Nd ₂ O ₃ , Gd ₂ O ₃ , Dy ₂ O
₃ , Er ₂ O ₃ , CaCO ₃ , SrCO ₃ , BaC
O ₃ , Mn ₂ O ₃ , NiO, CoO, ZrO ₂ , CeO
₂ , using FeO and MgO as starting materials,
Further, they were mixed so as to have the composition shown in Table 2 and mixed with zirconia balls for 10 hours, and then solid phase reaction was performed at 1300 ° C. for 10 hours. Further, in some cases, Al ₂ O ₃ , Si
To investigate the effect of O ₂ , TiO ₂ , Nb ₂ O _5, etc.,
The solid solution powder was added separately, and the powder was pulverized and mixed for 24 hours using zirconia balls. Then, it was formed into a cylindrical shape having an outer diameter of 15 mm, an inner diameter of 11 mm, and a length of 200 mm, and was fired at 1450 to 1500 ° C. to obtain a cylindrical sintered body having an open porosity of 38 to 41%. The impurities in the obtained sintered body were measured by fluorescent X-ray analysis, and the amount thereof was measured by ICP emission spectroscopic analysis.

With respect to the above-mentioned sintered body, the distance between fulcrums is 15
It was supported by a zirconia block so as to be 0 mm, kept at 1400 ° C. in the atmosphere for 10 hours, and the ratio of maximum deformation before and after heating divided by distance between fulcrums was taken as creep deformation. The measurement results are shown in Tables 1 and 2.

[0057]

[Table 1]

[0058]

[Table 2]

As is clear from the results of Tables 1 and 2, the amount of deformation is large when the substitution amount (y value) of the divalent metal is smaller than 0.25. On the other hand, when the y value exceeds 0.5, the sinterability deteriorates, and it is not possible to manufacture a cylindrical support tube having a predetermined open porosity. Similarly, the amount of trivalent metal substitution (x value) was less than 0.05 or more than 0.3, the amount of deformation was also large. Regarding the non-stoichiometric ones lacking the A site, when the z value became smaller than 0.9, a heterogeneous phase containing Mn other than the perovskite type was precipitated and the amount of deformation increased. Deformation was observed in all the samples that deviated from the scope of the present invention with respect to other x, y, z, and p values.

Also, the amount of deformation was large when the amount of impurities exceeded 0.8% by weight or the amount of Al or Si exceeded 0.2% by weight.

Example 2 In Tables 1 and 2 of Example 1, samples No. 1, 2, 3, 4, 1 were used.
1, 12, 19, 31, 33, 42, 45, 51, 5
Length 50c consisting of composition of 8, 65, 74, 76, 78
m support tube was prepared, and 11
A solid electrolyte made of ZrO ₂ containing 10 mol% of Y ₂ O ₃ was formed at 00 ° C., and 10 solid electrolytes were prepared for each. Sample No. 1, which was out of the scope of the conventional product and the present invention,
Regarding Nos. 2, 3, 12, 19, 31, and 45, creep deformation occurred and partial peeling of the solid electrolyte membrane was observed, but the other samples of the present invention showed no deformation even when the solid electrolyte was formed. Did not happen.

Example 3 Commercially available Y ₂ O ₃ , La ₂ O ₃ and Yb _{2 having} a purity of 99.9%.
O ₃ , Sc ₂ O ₃ , Nd ₂ O ₃ , Gd ₂ O ₃ , Dy ₂ O
₃ , Er ₂ O ₃ , CaCO ₃ , SrCO ₃ , BaC
O ₃ , Mn ₂ O ₃ , NiO, CoO, ZrO ₂ , CeO
₂ , FeO, Cr ₂ O ₃ and MgO were used as starting materials, and they were mixed to have the compositions shown in Tables 3 and 4 and mixed with zirconia balls for 10 hours, and then solid phase reaction was performed at 1300 ° C. for 10 hours. Let

This solid solution was prepared by using zirconia balls.
After further pulverizing and mixing for 24 hours, it is formed into a cylindrical shape having an outer diameter of 15 mm, an inner diameter of 11 mm, and a length of 200 mm.
Fired at 50-1500 ° C, open porosity is 38-41%
A cylindrical sintered body of was obtained.

For the obtained sintered body, the distance between fulcrums is 1
It was supported by a zirconia block so as to be 50 mm, kept at 1400 ° C. in the atmosphere for 10 hours, and the ratio of the maximum deformation before and after heating divided by the distance between fulcrums was taken as the creep deformation. The measurement results are shown in Tables 3 and 4. The total amount of Al and Si as metal impurities is 1000 ppm or less.
The total amount of 1, Si, Ti, Nb, Na and V is 1% by weight.
It was below.

[0065]

[Table 3]

[0066]

[Table 4]

As is clear from Tables 3 and 4, La
When the amount of substitution of Y with a rare earth element or Ca, Sr, or Ba deviates from the range of the present invention, the amount of deformation increased.

Furthermore, it is understood that the substitution of Cr for Mn at the B site improves the creep resistance. However, when the substitution amount e of Cr exceeds 0.5, the sinterability deteriorates.

[0069]

As described above, according to the present invention, the support tube itself has excellent creep resistance at high temperatures and improves the yield rate of cells in the cell manufacturing process.
It is possible to provide a fuel cell having excellent durability that does not cause defective connection between cells due to deformation even during long-term power generation during high-temperature operation.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a structure of a fuel battery cell according to the present invention.

FIG. 2 is a diagram for explaining the structure of a conventional fuel cell unit.

[Explanation of symbols]

 1 Support tube 2 Solid electrolyte 3 Fuel electrode 4 Interconnector 5 Air electrode

Claims (2)

[Claims] 1. A solid electrolyte fuel cell in which a solid electrolyte and a fuel electrode are sequentially laminated on a porous support tube having an air electrode capability, wherein the support tube has the following chemical formula 1. In the formula, A is at least one selected from the group of Y and rare earth elements, B is at least one selected from the group of Ca, Ba and Sr, and C is Co, Ni, Z.
It is composed of at least one selected from the group consisting of r, Ce, Fe and Mg, and x, y, z and p are 0.0
5 ≦ x ≦ 0.3, 0.25 ≦ y ≦ 0.5, 0.9 ≦ z ≦
1.05 and a composite perovskite type oxide satisfying 0 ≦ p ≦ 0.3, and Al and Si are 0.2 wt% or less in total of metal impurities other than the constituent elements.
A solid oxide fuel cell having a total amount of metal impurities of 0.8% by weight or less. 2. A solid electrolyte fuel cell in which a solid electrolyte and a fuel electrode are sequentially laminated on a porous support tube having an air electrode capability, wherein the support tube has the following chemical formula 2. In the formula, A is at least one selected from the group of Y and rare earth elements, B is at least one selected from the group of Ca, Ba and Sr, and C is Co, Ni, Z.
and at least one selected from the group consisting of r, Ce, Fe and Mg, and a, b, c, d and e are
0.02 ≦ a ≦ 0.50, 0.20 ≦ b ≦ 0.60,
0.90 ≤ c ≤ 1.05, 0 ≤ d ≤ 0.40 and 0.
A solid oxide fuel cell, comprising a composite perovskite oxide satisfying 02 ≦ e ≦ 0.50.