JP4720238B2 - Air electrode for solid oxide fuel cell and method for producing the same - Google Patents

Description

  The present invention relates to an air electrode used in a solid oxide fuel cell, and has a low reaction resistance during power generation and enables efficient power generation, and such a fuel cell. The present invention also relates to a method for producing an air electrode for use, and further to a solid oxide fuel cell using the air electrode.

In a solid oxide fuel cell (SOFC), an electrode reaction proceeds on the electrode.
On the air electrode, oxygen molecules involved in the reaction are dissociated into oxygen atoms and ionized. Therefore, the larger the surface area of the air electrode, the more reaction fields, and the electrode reaction proceeds smoothly. Further, the air electrode is required to have the ability to supply electrons as soon as possible to oxygen molecules or atoms, that is, high electron conductivity in order to ionize oxygen molecules.

If these conditions are satisfied, the electrode reaction at the air electrode, that is, the dissociation and ionization of oxygen molecules proceed smoothly, and efficient power generation is performed.
Generally, as the air electrode material of the solid oxide fuel cell, the general formula _{A 1-x B x C 1} -y D y O 3 (0.1 ≦ x ≦ 0.5,0 ≦ y ≦ 0. 3), A is one or both of La and Sm, B is at least one element selected from the group consisting of Sr, Ca and Ba, C is one or both of Co and Mn, D An oxide electrode in which is one or both of Fe and Ni is used.

In the solid oxide fuel cell, in principle, a material having high oxygen ion conductivity as an electrolyte and a material whose electron conductivity is negligible is used as an electrolyte, and a material having electron conductivity is used as an air electrode material. These must generally be oxide materials.
In addition, oxygen ions must move between the electrolyte material and the air electrode material, and must be firmly joined to the electrolyte material.

Thus, since the electrolyte material and the air electrode material are different materials, a joining process by sintering at a high temperature is required in order to firmly join the two.
However, the cathode material, whose starting form is particles, undergoes sintering during this high-temperature process, and as the particle diameter grows, the electrode surface area tends to decrease, the internal resistance of the cell increases, and the power generation capacity improves. There is a problem that is disturbed.

In order to solve such problems, a method has been proposed in which yttria-stabilized zirconia (YSZ), which is a typical electrolyte material, is mixed into the air electrode material to suppress sintering of the air electrode material (for example, , See Patent Document 1).
Japanese Patent Laid-Open No. 05-089884

  However, in the method described in Patent Document 1, since YSZ, which is an electrolyte material, does not have electronic conductivity, mixing YSZ with the air electrode material adversely affects the electronic conductivity as an electrode. Is concerned.

  The present invention has been made to solve the above-mentioned problems in the air electrode of a solid oxide fuel cell, and its object is to perform particle sintering without sacrificing electronic conductivity as much as possible. An object of the present invention is to provide an air electrode for a solid oxide fuel cell that can be suppressed, a method for manufacturing the air electrode, and a solid oxide fuel cell configured using such an air electrode.

  As a result of intensive studies on the air electrode material, its formation method, conditions, etc. in order to solve the above-mentioned problems in the air electrode of the solid oxide fuel cell, the present inventors By adding a small amount of an oxide of a transition metal such as Fe or Co, it was found that sintering during sintering can be suppressed without impairing the electronic conductivity of the air electrode material. It came to completion.

The present invention is based on the above knowledge, and the air electrode for a solid oxide fuel cell of the present invention has a porous structure in which particles of an air electrode material are connected to each other through a gap, Selected from the group consisting of particles of a first air electrode material represented by the general formula Sm _1-x Sr _x CoO ₃ (0.1 ≦ x ≦ 0.5) and Fe, Co, Ni, Cu and Zn It consists of particles of a second air electrode material made of an oxide of at least one element, and the mass ratio of the second air electrode material is in the range of 0.2 to 40 with respect to the first material 100. In the method for producing an air electrode of the present invention, the starting material for the first air electrode material is represented by the general formula Sm _1-x Sr _x CoO ₃ (0.1 ≦ x ≦ 0.5). As the starting material for the second air electrode material, air is used. An oxide precursor that can produce at least one oxide selected from the group consisting of iron oxide, cobalt oxide, nickel oxide, copper oxide, and zinc oxide by firing in , or the first air electrode material The oxide powder is finer than the oxide powder that is the starting material.
The solid oxide fuel cell of the present invention is characterized in that a dense electrolyte made of a solid oxide is sandwiched between the air electrode and the porous fuel electrode of the present invention.

According to the present invention, the second air electrode composed of an oxide of at least one element selected from the group consisting of the first air electrode material represented by the above general formula, Fe, Co, Ni, Cu and Zn. Since the material is mixed at a ratio of 0.2 to 40 with respect to the first material 100, the sintering phenomenon in which the material particles of the air electrode are combined at a high temperature to grow the particle size is inhibited, and the particle growth is prevented. In spite of the high temperature process, the particle size can remain small, the surface area of the air electrode can be kept high, and a large number of oxygen reaction fields can be secured. In general, an oxide is an insulator at room temperature, but has an electron conductivity above 400 ° C., which is the operating temperature of a solid oxide fuel cell (for example, Bull. Korean C em.Soc., 7 (5), 341 (1986), Bull.Korean Chem.Soc., 20 (9), 1005 (1999), CSJ Series Volume 5, Electroceramics in Japan II, 67-70 (1999), Advance. in Materials Science & Technology, 1 (1), 1 (1996)), even if added to the air electrode material, the adverse effect on the electron conductivity of the entire air electrode can be minimized, which is important as an electrode. Since the electronic conductivity as a performance can be kept high, the electrode reaction as an air electrode proceeds smoothly, and the electrode performance is improved.

  Applying such an air electrode to a solid oxide fuel cell, that is, forming a cell structure in which a dense electrolyte made of a solid oxide is sandwiched between the air electrode and the porous fuel electrode of the present invention described above. Thus, a solid oxide fuel cell having high power generation efficiency can be obtained.

Moreover, as a starting material of the first air electrode material represented by the general formula (Sm _1-x Sr _x CoO ₃ ), an oxide represented by such a general formula is used, and the second air electrode material As the starting material, an oxide precursor that can generate an oxide of at least one metal selected from the above metal group by firing in air is used, or at least one selected from the above metal group Since it is an oxide of a seed metal that is finer than the oxide powder that is the starting material of the first air electrode material, the adhesion between the air electrode material particles is improved. Thus, the baking temperature can be lowered, and the fuel cell air electrode of the present invention can be manufactured smoothly at low cost.

  Hereinafter, the air electrode for a solid oxide fuel cell of the present invention will be described in more detail together with the production method thereof.

Solid oxide fuel cell air electrode of the present invention, as described above, a powder of a first cathode material represented by a predetermined general formula, a second cathode material composed of transition metal oxides, In other words, it is composed of material particles that have electronic conductivity at the operating temperature of the fuel cell and have the function of suppressing sintering during sintering. As the oxide, for example, an oxide of Fe (iron), Co (cobalt), Ni (nickel), Cu (copper), or Zn (zinc) alone, or a material containing two or more of these in an arbitrary ratio Is used.

  In the air electrode for a solid oxide fuel cell according to the present invention, the ratio of the first material to the second material is set to a mass ratio of 0.2% for the second material relative to the first material 100. A range of 2 to 40 is desirable. That is, when the second material is less than 0.2 with respect to the first material 100, the sintering of the air electrode material during sintering cannot be suppressed, and the first material 100 If it exceeds 40, the electrode performance is likely to be lowered.

As the particle diameter of the oxide constituting the air electrode for the solid oxide fuel cell of the present invention, the average particle diameter of the oxide powder constituting the second material is the oxide powder constituting the first material. It is desirable to make it smaller than this, thereby improving the adhesion between the air electrode material powders, making it possible to form a strong electrode film, and so that the electrode can be baked at a lower temperature. It becomes possible to save energy in the manufacturing process.
In order to obtain an air electrode having such a particle structure, as described below, as a starting material for the second material, for example, an oxide precursor composed of an inorganic salt or an organic compound that becomes an oxide by firing in air, for example. When using a body, or as a starting material for the second material, an oxide that is not an oxide precursor but an oxide from the beginning, the oxide powder that is the starting material for the first material is used. Can also be produced by using fine oxide powder.

That is, as a first method for producing an air electrode for a solid oxide fuel cell of the present invention, an oxide represented by the above general formula is used as a starting material for the first material, As a starting material for the second material, it is desirable to use an oxide precursor that becomes a metal oxide as described above by firing in air .
For example, an ink or paste prepared by preparing an oxide powder that is a starting material of a first material, a binder, a dispersant, a solvent, and an oxide precursor that is a starting material of a second material is prepared. An air electrode for a solid oxide fuel cell can be obtained by applying it to the film formation surface, for example, the surface of an electrolyte made of a solid oxide or the surface of a support substrate, followed by firing in air.

Here, as the oxide powder that is a starting material of the first air electrode material, for example, a powder such as Sm _0.5 Sr _0.5 CoO ₃ can be used. Moreover, it is also possible to use the oxide powder which produces the said complex oxide by the solid-phase reaction in an electrode baking process as raw material powder.

  In addition, the type and amount of the binder, dispersion medium, solvent and the like are not particularly limited and may be appropriately selected from those conventionally used. Examples of the binder include methyl cellulose, ethyl cellulose, polyethylene oxide, and polyvinyl. Butyral, etc., as a dispersion medium, for example, polycarboxylic acid ammonium salt, polycarboxylic acid amine salt, various activators, etc. In addition to water etc., as a solvent, for example, organic solvents such as alcohol, toluene, xylene, methyl ethyl ketone, turpentine oil, etc. Can be used.

And as an oxide precursor which is a starting material of the second material, for example, iron oxide (Fe ₂ O ₃ ), cobalt oxide (CoO), nickel oxide (NiO), copper oxide is fired in air. An oxide precursor that becomes a transition metal oxide such as (CuO) or zinc oxide (ZnO), that is, an inorganic salt or an organic compound of a transition metal element can be used.
Specifically, iron chloride (FeCl ₃ ), iron acetate (Fe (CH ₃ COO) ₂ ), tri-isopropoxy iron (Fe (OCH (CH ₃ ) CH ₂ OCH ₃ ) ₃ ), cobalt chloride (CoCl ₂₎ ), cobalt acetate _{(Co (CH 3 COO) 2} ), di - iso propoxy cobalt _{(Co (Oi-C 3 H} 7) 2), nickel chloride (NiCl _2), nickel acetate _{(Ni (CH 3 COO) 2} ) , Nickel carbonate (NiCO ₃ ), cupric nitrate (Cu (NO ₃ ) ₂ ), cupric chloride (CuCl ₂ ), cupric acetate (Cu (CH ₃ COO) ₂ ), zinc nitrate (Zn (NO _{3) 2),} zinc chloride (ZnCl _2), zinc acetate _(Zn (CH 3 _COO) 2), di -n- propoxy zinc _{(Zn (OnC 3 H 7)} 2) , etc. can be suitably used.

  In addition to the above components, carbon or resin can be added to the ink or paste as a pore-forming agent as necessary.

In addition, as a second method for producing the air electrode for a solid oxide fuel cell of the present invention, an oxide is used similarly as a starting material of the first material, while the second material As the starting material, it can be produced by using an oxide powder having a finer particle size than the oxide powder that is the starting material of the first material.
That is, for example, iron oxide (Fe ₂ O ₃ ), cobalt oxide (CoO), nickel oxide (NiO) having an oxide powder as described above that is a starting material of the first material and a finer particle size configuration than that. ), Transition metal oxides such as copper oxide (CuO), zinc oxide (ZnO), and a binder, dispersant, solvent prepared ink or paste, and this ink or paste was applied to the film formation surface Thereafter, an air electrode for a solid oxide fuel cell can be obtained by firing in air. In addition, about a binder, a dispersion medium, a solvent, a pore making agent, etc., the same thing as the above can be used.

  The solid oxide fuel cell of the present invention uses the above-described air electrode, that is, a dense electrolyte made of a solid oxide is sandwiched between a porous fuel electrode and the above air electrode. Here, the electrolyte material in the fuel cell is not particularly limited, and known electrolyte materials such as YSZ, SSZ (scandium stabilized zirconia), SDC (samarium doped ceria), CGO (gallium doped ceria), and LSGM. (Lanthanum gallate) or the like can be used. As the fuel electrode material, a metal material such as Ni or a cermet material such as Ni—YSZ, Ni—SDC, Ni—CGO, Cu—YSZ, Cu—SDC, or Cu—GDC is used.

  Hereinafter, the present invention will be specifically described based on examples. Needless to say, the present invention is not limited to these examples.

Example 1
(1) Fabrication of fuel electrode substrate A mixed electrode of NiO and YSZ, a pore-forming agent, a binder, a dispersant, and a solvent are mixed, kneaded, and then molded by a press device, and a fuel electrode having a porosity of about 25%. A substrate was produced.

(2) Preparation of YSZ paste YSZ paste was prepared by mixing YSZ powder, a binder, a dispersant, and a solvent.

(3) Production of SDC paste An SDC paste was produced by preparing SDC powder, a binder, a dispersant, and a solvent.

(4) Preparation of air electrode paste Sm _0.5 Sr _0.5 CoO ₃ powder (average particle size 0.8 μm), FeCl ₃ , a binder, a dispersant, and a solvent were prepared to prepare an air electrode paste.
The addition amount of FeCl _3, assuming the FeCl ₃ is oxidized to all after firing _Fe 2 _{O 3,} the weight ratio of Sm _{0.5 Sr 0.5} CoO ₃ and _Fe 2 _{O 3} is 100: It was set to 1.

(5) Production of solid oxide fuel cell single cell The YSZ paste prepared in step (2) was applied to one side of the fuel electrode substrate obtained in step (1) by screen printing, and was sufficiently dried. Thereafter, the SDC paste prepared in the step (3) was further applied by screen printing and baked at a temperature of 1300 ° C. for 1 hour or longer to obtain a fuel electrode / electrolyte substrate.
A solid oxide fuel cell unit cell is obtained by applying an air electrode paste to the upper surface of the SDC layer of the fuel electrode / electrolyte substrate obtained as described above by screen printing and firing at a temperature of 1100 ° C. for 1 hour. Formed. The formation of the SDC layer is intended to avoid direct contact between the electrolyte layer made of YSZ and the air electrode layer containing Sm _0.5 Sr _0.5 CoO ₃ .

Example 2
An air electrode paste was prepared using CoCl ₂ instead of FeCl ₃ in the step (4) of Example 1. The amount of CoCl ₂ added was such that the mass ratio of Sm _0.5 Sr _0.5 CoO ₃ and CoO was 100: 1, assuming that this CoCl ₂ was all oxidized to CoO after firing. .
The solid oxide fuel cell single cell of this example was formed by repeating the same operation as in Example 1 except for the above.

Example 3
An air electrode paste was prepared using NiCl ₂ instead of FeCl ₃ in the step (4) of Example 1. It should be noted that the amount of NiCl ₂ added is such that the mass ratio of Sm _0.5 Sr _0.5 CoO ₃ and NiO is also 100: 1, assuming that this NiCl ₂ is all oxidized to NiO after firing. Blended into
The solid oxide fuel cell single cell of this example was formed by repeating the same operation as in Example 1 except for the above.

Comparative Example 1
The solid oxide fuel cell unit of this example was repeated by repeating the same operation as in Example 1 except that the air electrode paste was prepared in Step (4) of Example 1 without adding FeCl _3. A cell was formed.

Comparative Example 2
An air electrode paste was prepared using La _0.8 Sr _0.2 MnO ₃ (average particle size 0.8 μm) instead of Sm _0.5 Sr _0.5 CoO ₃ in step (4) of Example 1 above. .
By repeating the same operation as in Example 1 except that this air electrode paste was used and that the application of the SDC paste was omitted in step (5), the solid oxide fuel cell unit of this example was A cell was formed.

Comparative Example 3
In step (4) of Example 1 above, La _0.8 Sr _0.2 MnO ₃ (average particle size 0.8 μm) was used instead of Sm _0.5 Sr _0.5 CoO ₃ , and instead of FeCl ₃ . An air electrode paste was prepared using CoCl ₂ . At this time, the amount of CoCl ₂ added is such that the mass ratio of La _0.8 Sr _0.2 MnO ₃ and CoO is 100: 1, assuming that this CoCl ₂ is all oxidized to CoO after firing. did.
Except for this, the same operation as in Comparative Example 2 was repeated to form the solid oxide fuel cell single cell of this example.

Comparative Example 4
In step (4) of Example 1 above, La _0.8 Sr _0.2 MnO ₃ (average particle size 0.8 μm) was used instead of Sm _0.5 Sr _0.5 CoO ₃ , and instead of FeCl ₃ . An air electrode paste was prepared using NiCl ₂ . At this time, the amount of NiCl ₂ added is such that the mass ratio of La _0.8 Sr _0.2 MnO ₃ and NiO is 100: 1, assuming that this NiCl ₂ is all oxidized to NiO after firing. did.
Except for this, the same operation as in Comparative Example 2 was repeated to form the solid oxide fuel cell single cell of this example.

Comparative Example 5
In step (4) of Example 1 above, La _0.8 Sr _0.2 MnO ₃ was used instead of Sm _0.5 Sr _0.5 CoO ₃ and an air electrode paste was prepared without adding FeCl _3. did. Except for this, the same operation as in Comparative Example 2 was repeated to form the solid oxide fuel cell single cell of this example.

Example 7
An air electrode paste was prepared using Fe ₂ O ₃ powder (average particle size 40 nm) instead of FeCl ₃ in the step (4) of Example 1 above. The amount of Fe ₂ O ₃ powder added was such that the mass ratio of Sm _0.5 Sr _0.5 CoO ₃ and Fe ₂ O ₃ was 100: 1.
Then, the air electrode paste is applied by screen printing on the upper surface of the SDC layer of the fuel electrode / electrolyte substrate obtained in the same manner as in step (5) of Example 1, and fired at a temperature of 1000 ° C. for 1 hour. By doing so, a solid oxide fuel cell single cell was formed.

Example 8
An air electrode paste was prepared using CoO powder (average particle size 25 nm) in place of FeCl ₃ in step (4) of Example 1 above. Note that the amount of CoO _powder, the mass ratio of Sm _{0.5 Sr} 0.5 CoO ₃ and CoO 100: was 1.
Except for this, the same operation as in Example 7 was repeated to form the solid oxide fuel cell unit cell of this example.

Example 9
An air electrode paste was prepared using NiO powder (average particle size 25 nm) instead of FeCl ₃ in the step (4) of Example 1 above. Note that the amount of NiO _powder, the mass ratio of Sm _{0.5 Sr 0.5} CoO ₃ and NiO is 100: was 1.
Except for this, the same operation as in Example 7 was repeated to form the solid oxide fuel cell unit cell of this example.

Example 10
An air electrode paste was prepared using CuO powder (average particle size 50 nm) instead of FeCl ₃ in the step (4) of Example 1. Note that the amount of CuO _powder, the mass ratio of CuO and Sm _{0.5 Sr 0.5} CoO ₃ is 100: was 1.
Except for this, the same operation as in Example 7 was repeated to form the solid oxide fuel cell unit cell of this example.

Example 11
An air electrode paste was prepared using ZnO powder (average particle size 35 nm) in place of FeCl ₃ in step (4) of Example 1 above. Note that the amount of ZnO _powder, the mass ratio of Sm _{0.5 Sr 0.5} CoO ₃ and ZnO is 100: was 1.
Except for this, the same operation as in Example 7 was repeated to form the solid oxide fuel cell unit cell of this example.

Comparative Example 6
The same as in Example 1 except that the air electrode paste was prepared without adding FeCl3 in Step (4) of Example 1 and that the baking temperature of the air electrode in Step (5) was 1000 ° C. By repeating the operation, the solid oxide fuel cell unit cell of this example was formed.
In this example, since the air electrode was not sufficiently baked, the air electrode peeled after the baking step.

Measurement of Cell Output Each cell was evaluated for power generation using the single cells obtained in Examples 1 to 3, Examples 7 to 11 and Comparative Examples 1 to 6 .
The power generation temperature was 600 ° C., a power generation test was performed using hydrogen gas containing 3% water vapor on the fuel electrode side and dry air on the air electrode side, and a current-voltage curve was measured while controlling the output current. . The maximum output at that time is shown in Table 1.

As is apparent from the results of Table 1, solid oxide fuel cell single cells according to Examples 1 to 3 of the present invention baked using an Sm-Sr-Co based cathode paste containing an oxide precursor of a transition metal In comparison with Comparative Example 1, it was confirmed that power was generated at a high output even though the main component of the air electrode material was the same. On the other hand, in the single cells according to Comparative Examples 2 to 4 using La-Sr-Mn-based air electrode paste containing the same oxide precursor, compared to Comparative Example 5 not containing the transition metal oxide precursor, Although improved slightly, it turned out that it is inferior to the above-mentioned Examples 1-3.
Moreover, the solid oxide fuel cell single cell by Examples 7-11 of this invention which baked the air electrode paste containing the transition metal oxide powder finer than the oxide powder which is a starting material of the 1st air electrode material In Comparative Example 6 , that is, the transition metal oxide was not included, and the strength of the air electrode could not be sufficiently secured, so that it was difficult to measure the cell output, and it was baked at the same temperature condition. Regardless, it was found that the air electrode was sufficiently baked, and it was possible to generate electric power with an output equal to or higher than that of Comparative Example 1 baked at a higher temperature.

FIG. 1 shows cross-sectional photomicrographs (HAADF-STEM images, 20,000 times) of the air electrode layer of fuel cell single cells obtained in Examples 1 to 3 and Comparative Example 1. It can be seen that the air electrode layers in 1 to 3 clearly have more pores than Comparative Example 1, and the sintering of the air electrode material particles is suppressed. Moreover, in Example 7, since baking was possible at a temperature lower by 100 ° C., it can be seen that sintering of the air electrode material is suppressed as compared with other examples.
In addition, in the air electrodes of Examples 1 to 3 and 7, the presence of fine particles that are not observed in Comparative Example 1 has been confirmed, as marked with circles. Then, for the marked part, in the embodiment 1 is detected _Sm 0.5 _Sr 0.5 CoO ₃ not included in the (first material) Fe, in Example 3 Ni were detected. Further, in Example 2, it was found that a larger amount of Co component was contained than in the first material component. Furthermore, in Example 7, Fe was detected.

It is a microscope picture which shows the cross section of the air electrode obtained in Examples 1-3, 7 of this invention compared with the air electrode cross section of the comparative example 1. FIG.

Claims (8)

Having a porous structure in which particles of the air electrode material are connected to each other through a void;
Particles of a first air electrode material represented by the general formula Sm _1-x Sr _x CoO ₃ (0.1 ≦ x ≦ 0.5);
Comprising particles of a second air electrode material comprising an oxide of at least one element selected from the group consisting of Fe, Co, Ni, Cu and Zn ;
The air electrode for a solid oxide fuel cell, wherein the mass ratio of the second air electrode material is in the range of 0.2 to 40 with respect to the first material 100 . 2. The air electrode for a solid oxide fuel cell according to claim 1, wherein x is 0.5 in the general formula Sm _1-x Sr _x CoO ₃ . A claim 1 or 2 method for manufacturing a fuel cell air electrode according to, as a starting material of the first cathode material formula _{Sm 1-x Sr x CoO 3} (0.1 ≦ x ≦ 0. 5) is used, and the starting material for the second air electrode material is selected from the group consisting of iron oxide, cobalt oxide, nickel oxide, copper oxide and zinc oxide by firing in air. A method for producing an air electrode for a solid oxide fuel cell, wherein an oxide precursor capable of generating at least one oxide is used. An ink or paste prepared by preparing an oxide powder that is a starting material of the first air electrode material, a binder, a dispersant, a solvent, and an oxide precursor that is a starting material of the second air electrode material is prepared. The method for producing an air electrode for a solid oxide fuel cell according to claim 3 , wherein the ink or paste is applied and then fired in air. As a starting material of the second cathode material, Fe, Co, Ni, claim, characterized in that an inorganic salt and / or organic compound of at least one element selected from the group consisting of Cu and Zn 3 Or 4. A method for producing an air electrode for a solid oxide fuel cell as described in 4 . A claim 1 or 2 method for manufacturing a fuel cell air electrode according to the general formula as the starting material of the first cathode material _{Sm 1-x Sr x CoO 3} (0.1 ≦ x ≦ 0.5 using the oxide represented by), the starting material of the second cathode material, Fe, Co, Ni, an oxide of at least one element selected from the group consisting of Cu and Zn A method for producing an air electrode for a solid oxide fuel cell, comprising using an oxide powder finer than an oxide powder that is a starting material of the first air electrode material. A first oxide powder that is a starting material of the first air electrode material; and a second oxide powder that is a starting material of the second air electrode material and is finer than the first oxide powder. 7. A solid oxide fuel cell according to claim 6 , wherein an ink or paste prepared by mixing a binder, a dispersant, and a solvent is prepared, and the ink or paste is applied and then fired in air. Manufacturing method for air electrode. A cell for a solid oxide fuel cell, wherein a dense electrolyte made of a solid oxide is sandwiched between a porous fuel electrode and an air electrode according to claim 1 .

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