JP4888682B2 - Electrode for solid oxide fuel cell and method for producing the same - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a solid oxide fuel cell (SOFC), which has a small electrical resistance in the surface direction, excellent durability and current collecting performance, and particularly an electrode for a solid oxide fuel cell that is suitably used as an air electrode. The present invention relates to a structure and a manufacturing method thereof.

  In the current collector of a solid oxide fuel cell, since there are technically difficult elements regarding the connection between the power generation element and the external interconnector, there are many inventions and proposals that match the form of the power generation element. Has been made.

Among these, especially when targeting an air electrode, in order to ensure the electrical conductivity in the in-plane lateral direction, a method using an extremely thick air electrode is often employed (for example, Patent Document 1). reference).
International Publication No. 02/35628 Pamphlet

  However, a thick electrode layer as described in Patent Document 1 is difficult to form in the first place, obstructing gas exchange essential for power generation reaction, and making it difficult to increase the output. However, there are many problems such as application of thermal stress to other layers having different thermal expansion coefficients due to the difference in the thickness, causing peeling and cracking, and reducing reliability.

On the other hand, as a structure using other materials, for example, a technique such as embedding a platinum mesh in the electrode layer is also used, which is considered to be a very effective technique for improving the performance. It is bulky and very expensive.
In addition, such a method of embedding a platinum mesh is expensive and requires a high-temperature process corresponding to the sintering process, and a low-temperature manufacturing process aiming at low cost using a recent metal structure It is not always suitable for a cell operated at a low temperature.

  The present invention has been made to solve the above-mentioned problems in electrodes of solid oxide fuel cells, and the object of the present invention is to provide a solid oxide fuel cell aimed at low temperature operation at about 600 ° C. or lower. A high-performance electrode structure that is low-cost, excellent in durability, excellent in current collecting function and electrical conductivity, its manufacturing method, and such an electrode structure An object of the present invention is to provide a solid oxide fuel cell.

  In order to solve the above-mentioned problems in solid oxide fuel cell electrodes, the present inventors have made extensive studies on electrode materials, formation methods, film formation conditions, and the like. It has been found that by providing a sidewall of a metal piece made of a corrosion-resistant metal containing as a main component, durability is increased and conductivity in the electrode surface direction is improved, and the present invention has been completed.

The present invention is based on the above knowledge, and the electrode for a solid oxide fuel cell of the present invention is an electrode used in a fuel cell provided with an electrolyte made of a solid oxide, Protrusions made of a heat-resistant material that can ignore oxidation and softening at the operating temperature are regularly arranged on the surface of the electrolyte, made of a corrosion-resistant metal containing Ni and / or Co, and a porous electrode material. have a height that exceeds the maximum diameter of the particles constituting the metal piece surrounding at least side surfaces of the projections are spaced, with the porous electrode material is connected to the electrolyte surface, the metal strip It is characterized by covering at least a part of.

Also, the method for producing an electrode for a solid oxide fuel cell according to the present invention includes a heat resistant material layer on the surface of an electrolyte composed of a solid oxide, which can ignore oxidation and softening at the operating temperature of the solid oxide fuel cell. Forming step A, patterning the refractory material layer obtained by step A by photolithography and etching, leaving the refractory material as a protrusion on the surface of the electrolyte, and the surface of the electrolyte on which the protrusion is formed Coating with a metal film made of a corrosion-resistant metal containing Ni and / or Co, and the metal film obtained by the process C using an anisotropic etching method is etched by a film thickness to form the protrusions. A process D for leaving a metal piece on the side surface, a process E for reducing the height of the protrusion by etching, and a process for forming a porous electrode layer on the surface of the electrolyte after the processes up to E. It is characterized by including F.

  Furthermore, the solid oxide fuel cell of the present invention is characterized in that the electrode of the present invention is provided as an air electrode and / or a fuel electrode.

According to the present invention, since the metal pieces arranged at intervals on the surface of the solid oxide electrolyte make the electrical connection in the lateral direction of the electrode layer without completely covering the electrolyte surface, the lateral resistance is reduced. In particular, in an air electrode with generally high electrical resistance, the thickness can be greatly reduced to not only solve the conventional problems related to gas exchange but also to reduce costs and improve yield. Can do.
In addition, by using a metal material that does not become an insulating oxide as the metal piece material, even if the surface is oxidized during long-term operation, the metal oxide dispersion can be achieved as in the conventional simple electrode material. Unlike a porous body made of fine particles, it can function as a continuous electric conductor like a wiring material.

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

1A and 1B show a reference example of a solid oxide fuel cell electrode according to the present invention. The solid oxide fuel cell electrode 1 shown in the figure is made of a solid oxide. On the surface of the electrolyte 2, for example, metal pieces 3 made of a corrosion-resistant metal mainly composed of Ni, Co, or the like are formed in a grid shape at intervals, and the metal pieces 3 and the solid oxide electrolyte 2 are made of a porous electrode material. 4 is covered, and a folding screen-like and sidewall-like metal piece 3 is embedded in the porous electrode material 4.
Depending on the combination of the electrode material 4 and the electrolyte 2, as shown in FIG. 1A, a buffer intermediate layer 5 can be provided between them, but this is not always necessary.

  At this time, the solid oxide electrolyte 2 is not particularly limited, and known electrolyte materials such as YSZ (yttrium stabilized zirconia), SSZ (scandium stabilized zirconia), SDC (samarium doped ceria), GDC (gallium). Doped ceria), LSGM (lanthanum gallate), or the like can be used.

In addition, as an electrode material, a fuel electrode material such as cermet material such as Ni, Ni-YSZ, Ni-SSZ, Ni-SDC, Ni-GDC, Co-YSZ, Co-SSZ, Co-SDC, Co-GDC, etc. the use, can function the electrode as the fuel _{electrode, LSC (La 1-X Sr} X CoO 3), SSC (Sm 1-X Sr X CoO 3) cobalt oxide or the like, LSM ( _{La 1-X Sr X MnO 3} ), by using the _{LCM (La 1-X Ca X} MnO 3) air electrode materials, lanthanum-manganese oxide or the like, such as, can function the electrode as the fuel electrode.

In such an electrode structure, the metal piece 3 is embedded in a porous electrode material 4 in a folding screen shape or a side wall shape, and has a longitudinally long cross section, while ensuring conductivity in the thickness direction. , The obstruction factor of gas exchange is reduced.
Further, as shown in FIG. 2, the distance a between the metal pieces 3 can be 10 to 20 μm even in projection exposure or the like, and can be about 1 μm depending on conditions such as the flatness of the base. When the current collector 6 made of a current collecting material having a wire diameter much larger than the electrode thickness is brought into contact, the metal piece 3 makes the electrode thinner. Therefore, not only the problem of gas permeability can be solved, but also in-plane variations in electrode performance caused by variations in electron supply capability can be eliminated, and power generation performance can be improved.

The current collector 6 in contact with the electrode 1 is required to have gas permeability and flexibility, and as shown in FIG. 3, fibers made of heat-resistant and oxidation-resistant metal are used, or a thin plate processed into a dimple projection shape is pressed. However, in the case of a thin plate, the pitch of the dimples is on the order of millimeters or more, and even if the fiber diameter is small, it is realistic that about 50 μm. Therefore, even in the case of a mesh-type current collector, the fiber spacing b is 100 μm or more. However, the metal piece 3 improves the contact state with the current collector 6.
Moreover, in the electrode 1, since the metal piece 3 has reached the lower layer direction of the electrode material, electrons are supplied with lower resistance from the surface to the vicinity of the electrolyte than when the current collector 6 is brought into contact. Will also contribute to improved power generation performance.

  1 shows an example in which the metal piece 3 is formed in a bowl shape, but it is not limited to such a shape. For example, various shapes such as a mesh shape, a round shape, and a polygon shape may be arbitrarily selected. Can be selected.

In the solid oxide fuel cell electrode of the present invention, protrusions having heat resistance are regularly arranged on the surface of the electrolyte 2 so that the metal pieces 3 surround at least the side surfaces of the protrusions . Thereby, even when the metal piece 3 is thin, the contact pressure of the interconnector is received by the protrusions, and the metal piece 3 can carry out electrical conduction while protecting the porous fragile electrode material layer. In this case, it is preferable that the width of the protrusion is not so large.

In this case, it is desirable that the height of the metal piece 3 is larger than the protrusion. That is, when the metal piece 3 protrudes further upward from the side wall of the protrusion and has a structure like a so-called folding screen, the top of the metal piece 3 is pushed at the time of contact with the interconnector or the current collector. Is crushed and covers the upper end of the protrusion, which becomes an electrical connection point with the interconnector or the current collector.
In particular, when it is manufactured by a process described later, it tends to bend to the top of a protrusion having heat resistance in shape and tends to be a strong electrical connection point. Thus, not only does the electrical connection point increase within the electrode, it also greatly improves the electrical connection to the interconnector or current collector.

  Furthermore, in the electrode for a solid oxide fuel cell of the present invention, a porous electrode material layer can be provided between the electrolyte 2 and the bottom of the metal piece 3, and by adopting such a structure, Since the metal piece 3 and the lower part of the protrusion also function as active points, the effective area of the electrolyte surface is maintained as in the case where the metal piece 3 is not formed.

  Below, the manufacturing method of the electrode for solid oxide fuel cells of the said structure is demonstrated based on Fig.3 (a)-(i).

First, as shown in FIG. 3A, a heat-resistant material layer 11 is deposited on the surface of the electrolyte 2 (step A).
As such a heat-resistant material, Si, SiO ₂ , GeO ₂ , Al ₂ O ₃ or the like can be used.

  Next, as shown in FIG. 3B, a photoresist 12 used in a semiconductor process is formed on the heat-resistant material layer 11, and as shown in FIG. 3C, a resist pattern is formed by photolithography. To do.

As shown in FIG. 3D, the resist pattern is used as a mask, and etching is performed according to the type of the heat-resistant material layer 11 so that the side wall of the heat-resistant material layer 11 is close to the electrolyte vertical.
For example, in the case where the heat-resistant material layer 11 is Si, an RIE that applies high frequency power of 13.56 MHz to the electrolyte 2 side using an etching gas in which HBr, NF ₃ , O _2, and He are mixed is used. Etching can be easily performed by adopting a known technique called “active ion etching”. In addition to the above, combinations of various gas types can be used depending on the type of heat-resistant material. For SiO ₂ , etching using CF ₄ and H ₂ gas or the like is possible, and for Al ₂ O ₃ , a gas containing a chlorine-based etching gas such as BCl ₃ can be used.

  After the etching, as shown in FIG. 3E, the resist 12 is removed by an ashing process, whereby the protrusions 13 made of the heat-resistant material remain on the surface of the electrolyte 2 (process B).

Next, as shown in FIG. 3F, a metal film 14 such as Ni is formed with good step coverage to coat the surfaces of the electrolyte 2 and the protrusions 13 (step C). This corresponds to what is called “conformal” in the semiconductor field.
As the metal film 14, in addition to Ni, Fe, Co, or an alloy thereof can be used.

Next, as shown in FIG. 3G, the metal film 14 is etched only in the vertical direction by an amount corresponding to the film thickness by using an anisotropic etching method, so that the metal film 14 is formed only on the side surface of the protrusion 13. Leave (step D). This corresponds to what is called a “side wall” in the semiconductor process.
That is, in the case of an etching method in which etching proceeds preferentially in the vertical direction, the thickness of the film formed on the side surface of the protrusion 13 corresponds to the thickness of the flat portion, and thus the flat portion is removed by etching. On the other hand, the metal film 14 is left on the vertical side surface to become the metal piece 3.

In the field of semiconductors, the above etching method requires anisotropy as in the case of the RIE method. However, when a transition metal is used for the metal film as in the present invention, etching is performed with an etching gas used in semiconductors. I can't.
This is because the vapor pressure of transition metal chlorides and fluorides is very low, and after the reactants are formed on the surface during the etching operation, they are not removed by evaporation, so the reaction does not proceed, and as a result This is because etching does not proceed.

In the present invention, etching can be performed by using a method called “ion milling” in which Ar ions collide with the surface from the vertical direction and are physically removed. In addition, etching is performed by activating a mixed gas of CO gas and NH ₃ gas with low-temperature plasma (glow discharge) to form a carbonyl compound having a vapor pressure on the surface of the transition metal and removing it. When this method is used, a practical etching rate can be obtained as compared with the ion milling method.

Then, after forming the sidewalls of the metal pieces 3 on the side surfaces of the protrusions 13 by the above process, the protrusions 13 made of a heat-resistant material are completely removed by etching as shown in FIG. (Process E).
In addition to the RIE method, there are other methods for removing the protrusions 13. Since anisotropy is not required at the time of removal as in the RIE method, simple plasma etching using a fluorine-based compound gas or wet etching using phosphoric acid may be used particularly for Al ₂ O _3, and in the case of GeO ₂ , Can be removed.

Thereafter, as shown in FIG. 3 (i), the porous electrode material 4 as described above that functions as an air electrode or a fuel electrode is formed on the sidewall surfaces of the electrolyte 2 and the metal piece 3 (step F). Thus, the solid oxide fuel cell electrode 1 having the structure shown in FIG. 1 is completed.
For forming the porous electrode material 4 at this time, methods such as sputtering vapor deposition, gas deposition, aerosol deposition, cold spray, plasma spraying, CVD, and spray pyrolysis deposition are used alone. Or a combination of two or more techniques can be applied.

The protrusion 13 described above is used as a mechanical pressure-resistant structure by being left on the surface of the electrolyte 2 without being completely removed, thereby forming the electrode structure of the present invention .
This manufacturing process will be described with reference to FIGS.

That is, the steps shown in FIGS. 4A to 4G are basically the same as those shown in FIG.
After the side wall of the metal piece 3 is formed, the top portion of the protrusion 13 is slightly etched in the etching of the protrusion 13, and the tip of the side wall (metal piece 3) is protruded as shown in FIG. The shape protruded on the top 13.

  In this state, as shown in FIG. 4I, the formation of the solid oxide fuel cell electrode 1 is completed by forming the porous electrode material 4 in the same manner as described above.

After the porous electrode material 4 is formed, when the current collector 6 is brought into contact with the surface of the electrode 1 as shown in FIG. 5 (a), a metal piece as a side wall as shown in FIG. 5 (b). The tip of 3 falls to the upper end side of the protrusion 13 and becomes an electrical contact with the current collector 6.
In the case of such a structure, the projection 13 receives not only the pressing pressure of the current collector 6 and prevents the porous electrode material 4 from being crushed, but also the electrode due to friction of the current collector 6 due to thermal expansion and contraction. Can also be prevented.

  The protrusion 13 in this case needs to be a heat-resistant material that can ignore oxidation and softening at the operating temperature of the solid oxide fuel cell. For example, in addition to Si, the above-described electrolyte material Alternatively, a dense (non-porous) electrode material or the like can be used.

  Further, prior to the step A shown in FIG. 3A, that is, the step of forming the heat-resistant material layer 11 on the surface of the electrolyte 2, the heat-resistant material layer 11 with the electrode material layer 7 formed on the surface of the electrolyte 2. 6 is performed, and thereafter, the same process is carried out, whereby the metal piece 3 can be structured so as to float in the electrode material as shown in FIG. 6, whereby the lower part of the metal piece 3 (side wall) is formed. In addition, gas can permeate, and the electrode area increases accordingly, which improves battery performance.

  Similarly, prior to step A shown in FIG. 4A, the heat-resistant material layer 11 is vapor-deposited in a state where the electrode material layer 7 is formed on the surface of the electrolyte 2, and thereafter the same steps are repeated, whereby FIG. As shown in FIG. 3, the metal piece 3 and the protrusion 13 that reinforces the metal piece 3 can float in the electrode material, so that the current collector 6 (mesh structure only) can be obtained without sacrificing the area of the electrolyte interface. In addition, a plate-like current collector can also be used to disperse and receive stress from the surface, and the lower layer of the metal piece 3 can also be used as an active part while maintaining the pressure-resistant structure. It becomes like this.

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

( Reference Example 1)
8YSZ (8 mol% yttrium-stabilized zirconia) was used as the electrolyte 2, and Si having a thickness of 2 μm was vapor-deposited on this surface to form the heat-resistant material layer 11 (see FIG. 3A).
Next, a photoresist 12 used in a semiconductor process was formed on the Si layer (see FIG. 3B), and a resist pattern was formed by photolithography (see FIG. 3C).

Next, using the resist pattern as a mask, etching is performed by the Si dry etching process, that is, the RIE method (etching gas: HBr + NF ₃ + O ₂ + He mixed gas, applied high frequency: 13.56 MHz) so that the side wall of Si becomes nearly vertical. (See FIG. 3 (d)).
Then, by removing the photoresist 12 by an ashing process, a protrusion 13 for forming a metal piece was formed (see FIG. 3E).

Next, a metal film 14 made of Ni was formed to a thickness of 1 μm on the surfaces of the electrolyte 2 and the protrusions 13 (see FIG. 3F).
Further, the Ni film 14 is anisotropically etched using an ion milling method in which Ar ions collide from the vertical direction, and the Ni film 14 remains only on the side surfaces of the protrusions 13 by etching the Ni film by the thickness. Thus, a metal piece 3 was obtained (see FIG. 3G).

After forming the side wall (metal piece 3) made of Ni on the side surface of the protrusion 13 by the above process, the protrusion 13 made of Si was completely removed by exposing it to NF ₃ gas plasma (FIG. 3 ( h)).

  Thereafter, using the AD method (aerosol deposition method), SSC (samarium-strontium-cobalt composite oxide) is used as the porous air electrode material 4 on the surface of the electrolyte 2 and the Ni sidewall (metal piece 3). By forming the film, a solid oxide fuel cell electrode (air electrode) 1 having the structure shown in FIG. 1 was obtained (see FIG. 3I).

  Next, as the current collector 6, a fiber body in which fibers of 100 μm diameter made of Inconel 750 are combined to a thickness of 1.3 mm is prepared, and a stainless steel material having a thickness of 100 μm (product name: ZMG232, manufactured by Hitachi Metals, Ltd.) is prepared. A current collector layer that also serves as a gas flow path was configured by sandwiching between the metal separator and the air electrode 1 formed in the above process.

When 10 layers of cells having such a structure are stacked and pressed so that each of the fibrous bodies has a thickness of 1 mm, the pressure becomes 20 g / cm ² , and the current collector 6 made of the fibrous body has each air electrode. Are pressed at the same pressure.
Gas pipes are connected to each layer to supply gas necessary for power generation. By holding the cell stack having such a structure in an atmosphere of 600 ° C., six power generation tests are performed. Repeated.

As a result, although there was some variation, it was confirmed that the performance in which the electrical resistance component was reduced by about 10% was maintained. In addition, due to the pressing pressure as described above, although some indentation on the upper part of the metal piece is recognized, the generation of scratches and chipping powder due to deformation and contraction of the metal fiber due to thermal stress is not recognized in the electrode material part, It has been found that a good electrode surface is maintained.
The present invention can also be applied to the fuel electrode side. In this case, a typical example of securing the current collection in the fuel electrode layer in a cell called an air electrode support type using a lanthanum gallate material is typical. It will be something.

(Example 2)
An example in which the protrusion 13 is left on the surface of the electrolyte 2 and used as a mechanical pressure-resistant structure will be described.

In the reference example 1, when the protrusion 13 is etched after forming the Ni sidewall (metal piece 3), the top of the protrusion 13 is slightly etched as shown in FIG. 4 (h). The tip of the sidewall was shaped to protrude from the upper end surface of the protrusion 13 by being held in place.
And as shown in FIG.4 (i), the electrode (air electrode) 1 of the solid oxide fuel cell of this example was obtained by forming SSC as the air electrode material 4 into a film.

  In the air electrode 1 of this example, when the current collector 6 is brought into contact with the surface, the tip of the sidewall 3 falls to the protrusion side due to its shape, and as shown in FIG. The projection 13 receives the pressing force of the current collector 6 to prevent the air electrode material 4 from being crushed and also prevents the air electrode from being broken due to friction with the current collector 6. It will be.

( Reference Example 3)
Here, an example in which the electrode material layer 7 is formed in the lower layer of the metal piece 3 in order to ensure the effective area of the electrolyte 2 will be described.
That is, prior to the step shown in FIG. 3A for forming the heat-resistant material layer 11 on the surface of the electrolyte 2, the porous electrode material layer 7 also made of SSC was formed on the surface of the electrolyte 2.

Hereinafter, similarly to the reference example 1, by repeating the steps of FIGS. 3A to 3I, the solid oxide fuel cell electrode (air electrode) 1 having the structure shown in FIG. 6 is obtained. Obtained.

  In the air electrode 1 of the present example, as described above, the effective area of the electrolyte 2 is ensured at the same level as the case where the metal piece 3 is not formed, and gas can permeate the lower part of the metal piece 3. Therefore, the electrode area is also increased, and the battery performance can be improved.

Example 4
Here, an example in which the electrode material layer 7 is formed in the lower layer of the metal piece 3 in order to ensure the effective area of the electrolyte 2 while maintaining the pressure-resistant structure by leaving the protrusions 13 will be described.
That is, prior to the step shown in FIG. 4A for forming the heat-resistant material layer 11 on the surface of the electrolyte 2, the porous electrode material layer 7 also made of SSC was formed on the surface of the electrolyte 2.

  Thereafter, in the same manner as in Example 2 above, by repeating the steps of FIGS. 4A to 4I, a solid oxide fuel cell electrode (air electrode) 1 having a structure as shown in FIG. Obtained.

  In the air electrode 1 of the present example, the effective area of the electrolyte 2 is similarly secured at the same level as when the metal piece 3 is not formed, and the lower layer of the metal piece 3 can also be used as an active part to improve battery performance. At the same time, the protrusion 13 and the metal piece 3 can receive and distribute the pressure of the current collector 6 on the upper end surface.

It is sectional drawing (a) and top view (b) which show the structure of the electrode for solid oxide fuel cells as a reference example of this invention. It is sectional drawing which shows the state which has arrange | positioned the electrical power collector to the electrode for solid oxide fuel cells shown in FIG. FIG. 2 is a process diagram for sequentially explaining a production process of the solid oxide fuel cell electrode shown in FIG. 1. It is process drawing which demonstrates sequentially the manufacturing process of the electrode for solid oxide fuel cells of this invention. (A) It is sectional drawing which shows the state which has arrange | positioned the electrical power collector to the electrode for solid oxide fuel cells manufactured by the process shown in FIG. (B) It is a principal part expanded sectional view of Fig.5 (a). It is sectional drawing which shows the structure of the electrode for solid oxide fuel cells which concerns on the form which interposed the electrode material layer between electrolyte and the metal piece. It is sectional drawing which shows the structure of the electrode for solid oxide fuel cells which concerns on other embodiment of this invention which interposed the electrode material layer between electrolyte and the metal piece.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode for solid oxide fuel cells 2 Electrolyte 3 Metal piece 4 Porous electrode material 7 Electrode material layer 11 Heat-resistant material layer 13 Protrusion 14 Metal film

Claims (6)

An electrode used in a fuel cell having an electrolyte made of a solid oxide ,
Projections made of a heat-resistant material that can ignore oxidation and softening at the operating temperature of the solid oxide fuel cell are regularly arranged on the surface of the electrolyte.
Made corrosion resistant metal containing Ni and / or Co, greater than the maximum diameter of the particles constituting the porous electrode material have a height, metal piece surrounding at least side surfaces of the projections are spaced apart ,
A solid oxide fuel cell electrode, wherein a porous electrode material is connected to an electrolyte surface and covers at least a part of the metal piece. 2. The electrode for a solid oxide fuel cell according to claim 1, wherein the metal pieces are arranged in a bowl shape. Solid oxide fuel cell electrode according to claim 1 or 2 height of the metal strip being greater than the height of the projections of the metal strip is surrounded. The electrode for a solid oxide fuel cell according to any one of claims 1 to 3, wherein a metal piece is disposed on the surface of the electrolyte via a porous electrode material layer. Forming a heat-resistant material layer capable of ignoring oxidation and softening at the operating temperature of the solid oxide fuel cell on the surface of the electrolyte made of solid oxide; and
Patterning the refractory material layer by photolithography and etching to leave a protrusion made of the refractory material on the surface of the electrolyte; and
Coating the surface of the electrolyte that has undergone the above-described process with a metal film made of a corrosion-resistant metal containing Ni and / or Co ; and
A step D of etching the metal film by a thickness using an anisotropic etching method to leave a metal piece on the side surface of the protrusion; and
Step E of reducing the height of the protrusions by etching;
A method for producing an electrode for a solid oxide fuel cell, comprising sequentially performing a step F of forming a porous electrode layer on the surface of the electrolyte that has undergone the above steps.
  A solid oxide fuel cell comprising the electrode according to any one of claims 1 to 4.

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