JP2001015128A - Cylindrical solid electrolyte type fuel cell and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical solid electrolyte type fuel cell and its manufacturing method, causing power generating characteristics and yield to be enhanced, by enhancing the adhesive force of an air electrode layer to a solid electrolyte layer. SOLUTION: This cylindrical solid electrolyte type fuel cell is made up of a cylindrical first air electrode 11, a second air electrode 12 formed on an outer circumferential surface of the first air electrode 11, a solid electrolyte layer 13 formed on an outer circumferential surface of the second air electrode 12, and a fuel electrode layer 14 formed on an outer circumferential surface of the solid electrolyte layer 13. The thickness of the solid electrolyte layer 13 is 20 to 150 μm and the thickness of the second air electrode 12 is 50 to 300 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical solid oxide fuel cell and a method for producing the same.

[0002]

2. Description of the Related Art Solid-electrolyte fuel cells are highly expected as third-generation fuel cells because of their high power generation efficiency and high-quality heat. ing.

[0003] A cylindrical solid oxide fuel cell is shown in FIG.
As shown in FIG. 1, a solid electrolyte layer 2 of, for example, stabilized ZrO ₂ containing Y ₂ O ₃ is formed on the surface of an air electrode 1 made of a LaMnO ₃ -based material, and a Ni / ZrO 2 is formed on this surface as a fuel electrode layer 3. ₂ (containing Y ₂ O ₃ ) is formed.
An interconnector layer 4 made of a LaCrO ₃ -based material is formed so as to penetrate the solid electrolyte layer 2 and contact the air electrode layer 1 for connection between cells. Thus, a plurality of cells are connected via the interconnector layer 4. Power generation is performed at 1000 ° C. by supplying air (oxygen) inside the air electrode 1 and hydrogen, methane, etc. outside the fuel electrode layer 3.

[0004] In such a fuel cell, generally, a support made of, for example, an air electrode is prepared, and a solid electrolyte, an interconnector and a fuel electrode are formed on the surface of the support by a slurry coating method, a thermal spraying method, an electrochemical deposition method. (EVD) or the like. In some cases, a method in which a solid electrolyte, an interconnector, and a fuel electrode are sequentially formed by a method combining them is adopted.

However, according to the above-described manufacturing method, the manufacturing process itself is complicated, the apparatus is extremely expensive, and the number of cell components is large. However, there was a drawback that was extremely high.

Therefore, conventionally, a sheet-shaped solid electrolyte layer molded body made of a solid electrolyte material is wound around a cylindrical molded body composed of at least an air electrode, and this is simultaneously fired. According to the method, a fuel cell can be manufactured in a very simple and small number of steps (see Japanese Patent Application Laid-Open No. H10-162847).

[0007]

However, in the manufacturing method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 10-162847, it is difficult to handle a thin sheet-like solid electrolyte layer molded body, and as a result, the yield of cell production is poor. There was a problem of becoming. Further, a method is disclosed in which a sheet-shaped solid electrolyte layer formed body made of a solid electrolyte material is simply wound around a cylindrical air electrode formed body made of an air electrode material and fired at the same time. There was also a problem that the adhesion of the electrolyte layer was weak, resulting in low power generation performance.

An object of the present invention is to provide a cylindrical solid electrolyte fuel cell capable of improving the adhesive force between an air electrode and a solid electrolyte layer and improving power generation characteristics and yield, and a method of manufacturing the same.

[0009]

According to the present invention, there is provided a cylindrical solid oxide fuel cell unit comprising: a first air electrode having a cylindrical shape; a second air electrode layer formed on an outer peripheral surface of the first air electrode; It comprises a solid electrolyte layer formed on the outer peripheral surface of the second air electrode layer, and a fuel electrode layer formed on the outer peripheral surface of the solid electrolyte layer. Here, the thickness of the solid electrolyte layer is 20 to 150.
μm, and the thickness of the second air electrode layer is desirably 50 to 300 μm.

Further, the method for manufacturing a cylindrical solid oxide fuel cell according to the present invention comprises the steps of: forming a cylindrical first air electrode formed body made of an air electrode forming material; Producing a second air electrode layer molded article, producing a sheet-shaped solid electrolyte layer molded article made of the solid electrolyte forming material, and applying the solid electrolyte layer molded article to the second air electrode layer molded article. And forming a composite sheet compact on the outer peripheral surface of the first cathode compact, and applying the second cathode layer compact to the first cathode compact. This is a method including a step of winding and laminating so as to be in contact with each other, and a step of firing the cylindrical laminated molded body.

Here, the method further includes a step of producing a sheet-shaped fuel electrode layer molded article made of the fuel electrode forming material, and a step of producing a sheet-shaped interconnector layer molded article made of the interconnector forming material. A step of laminating a fuel electrode layer molded article on the surface of the composite sheet molded article after the step of winding and laminating the sheet molded article, and exposing the second air electrode layer between both end faces of the solid electrolyte layer molded article. And laminating the interconnector layer molded body on the surface of the molded body.

Further, after the step of producing the first cathode electrode molded body, a step of calcining the first cathode electrode molded body is provided, and the step of winding and laminating the composite sheet molded body is performed by the first air electrode forming step. Preferably, a step of winding and laminating the composite sheet compact on the outer peripheral surface of the pole calcined body such that the second cathode layer compact abuts on the first cathode calcined body is desirable.

[0013]

According to the cylindrical solid electrolyte fuel cell of the present invention, the second air electrode layer is formed on the outer peripheral surface of the first cylindrical air electrode, and the solid electrolyte is formed on the outer peripheral surface of the second air electrode layer. Since the layer is formed, the bonding strength between the first air electrode and the solid electrolyte layer is improved, and the performance of the cell can be improved. The thickness of the solid electrolyte layer is 20 to 150 μm, and the thickness of the second air electrode layer is 50 to 300 μm.
By setting the thickness to μm, the joining strength between the first air electrode and the solid electrolyte layer can be further improved, and the performance of the cell can be further improved.

In addition, such a cylindrical solid oxide fuel cell has a cylindrical first air electrode formed body made of an air electrode forming material, and a sheet-shaped second air electrode layer formed body made of an air electrode forming material. Producing a sheet-shaped solid electrolyte layer molded body made of a solid electrolyte forming material, producing a composite sheet molded body in which the solid electrolyte layer molded body is laminated on the second air electrode layer molded body,
It can be easily obtained by winding and laminating a composite sheet molded body on the outer peripheral surface of the first air electrode molded body and firing the cylindrical laminated molded body.

Further, by employing such a manufacturing method, the thickness of the composite sheet molded body wound around the cylindrical first air electrode molded body is large, so that the handling becomes easy, and the production yield at the time of winding can be improved. In addition, the second
The solid electrolyte layer molded body is laminated on the air electrode layer molded body, and thereafter, the composite sheet molded body is formed on the outer peripheral surface of the first air electrode molded body, and the second air electrode layer molded body is formed of the first air electrode molded body. The second air electrode layer molded body and the first air electrode molded body, and the second air electrode layer molded body and the solid electrolyte layer molded body are well conformed to each other because they are wound and laminated so as to contact with each other. The first air electrode molded body and the second air electrode layer molded body are made of the same air electrode forming material, so that the conformity is good, and as a whole, the bonding strength between the first air electrode and the solid electrolyte layer after firing can be improved. . Further, the contact at the interface between the second air electrode layer molded body and the solid electrolyte layer molded body becomes good, and the polarization resistance caused by the poor contact can be reduced, and as a result, the power generation characteristics can be improved.

Further, since the first air electrode, the second air electrode layer, the solid electrolyte layer, the fuel electrode layer, and the interconnector layer can be simultaneously fired at once, the manufacturing process of the cylindrical solid electrolyte fuel cell can be greatly reduced. Yes, and more easily.

Further, after the step of manufacturing the first cathode electrode molded body, the method further comprises a step of calcining the first cathode electrode molded body, and a step of winding and laminating the composite sheet molded body.
Since the composite sheet compact was wound and laminated on the outer peripheral surface of the first cathode calcined body so that the second cathode layer compact was in contact with the first cathode calcined body, First
Since the first air electrode calcined body has higher strength than the air electrode molded body, it is possible to improve the production yield when winding the composite sheet molded body.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A cylindrical solid oxide fuel cell according to the present invention will be described with reference to FIG. In FIG. 1, the fuel cell includes a cylindrical first air electrode 11, a second air electrode layer 12 formed on the outer peripheral surface of the first air electrode 11, and an outer peripheral surface of the second air electrode layer 12. Solid electrolyte layer 13 formed on
And a fuel electrode layer 14 formed on the outer peripheral surface of the solid electrolyte layer 13, and an interconnector layer 15 connected to the second air electrode layer 12 and having a surface exposed to the outside.

The thickness of the solid electrolyte layer 13 is 20 to 150 μm.
m, the thickness of the second air electrode layer 12 is 50 to 300 μm. The thickness of the solid electrolyte layer 13 is particularly 50 to 100 μm.
m is desirable, and the thickness of the second air electrode layer 12 is particularly 100 to 100.
200 μm is desirable.

When the thickness of the solid electrolyte layer 13 is less than 20 μm and when the thickness of the second air electrode layer 12 is less than 50 μm, the power generation performance is excellent, but the solid electrolyte layer 13 and the second air electrode layer 12 are manufactured. This makes it difficult to handle the molding sheet, and the yield of cell production deteriorates. When the thickness of the solid electrolyte layer 13 is greater than 150 μm, and when the thickness of the second air electrode layer 12 is greater than 300 μm, the bonding state between the solid electrolyte layer 13 and the second air electrode layer 12 is deteriorated, and This is because the output density at the time tends to decrease.

A method for manufacturing a cylindrical solid oxide fuel cell according to the present invention will be described. First, a cylindrical first air electrode molding made of an air electrode forming material, a sheet-shaped second air electrode layer molding made of an air electrode forming material, and a sheet solid electrolyte layer molding made of a solid electrolyte forming material are prepared. Make it.

The cylindrical first air electrode molded body is produced to a predetermined size by a method such as extrusion molding or hydrostatic molding (rubber press) of an air electrode forming material, and has a thickness of 1 to 3 mm. Is appropriate. At this time, as the air electrode-forming material consists of LaMnO ₃ based compositions, Ca part of La 10-20 atomic% in particular, Sr, LaMnO ₃ based composition substituted with alkaline earth elements such as Ba A substance comprising a substance and a desired organic component is used.

The sheet-shaped second air electrode layer molded article and the sheet-shaped solid electrolyte layer molded article can be obtained by preparing sheet-shaped molded articles by a well-known method such as a doctor blade method or an extrusion method. Can be In this case, the second air electrode layer molded body may use the same material as the first air electrode molded body. Further, the solid electrolyte layer molded body is Y, Yb, Sc, S
oxides composed of rare earth elements such as m, Nb and Dy
A partially stabilized ZrO ₂ powder or stabilized ZrO ₂ powder containing 20 mol%, the solid electrolyte-forming material comprising the desired organic component is used.

The thickness of the solid electrolyte layer molded body is about 30
The thickness of the second air electrode layer molded body is suitably about 70 to 350 μm.

Next, a composite sheet molded body is prepared by laminating and joining the second air electrode layer molded body and the solid electrolyte layer molded body.
The composite sheet compacts can be joined together by isostatic pressing or by passing between rolls heated to a temperature of around 50 ° C. Further, the composite sheet molded body may be joined by a biaxial press in a heated state. At this time, the pressure applied to the composite sheet molded body is 0.1 to 0.5 t.
A relatively small pressure of / cm ² is preferred. Further, an acrylic resin or an organic solvent may be interposed between the second air electrode layer molded body and the solid electrolyte layer molded body for the purpose of strengthening the adhesive force. And / or an adhesive obtained by mixing a solid electrolyte forming material and a commercially available binder may be interposed.

Thereafter, a composite sheet compact is wound around the outer peripheral surface of the first cathode compact, wound and laminated so that the second cathode layer compact is in contact with the first cathode compact, and joined. . At this time, it is preferable that the bonding is performed with an acrylic resin, an organic solvent, or the like interposed in the same manner as above.

Next, the cylindrical laminated molded article formed by winding and joining the composite sheet molded article on the outer peripheral surface of the first air electrode molded article is fired. Baking is performed at 1300-1500 ° C. in an oxidizing atmosphere.
At the same time for 3 to 10 hours so that at least the solid electrolyte layer becomes dense with a relative density of 96% or more. At this time, it is sufficient that the relative density of the first air electrode molded body and the second air electrode layer molded body is about 60 to 80%.

As shown in FIG. 1, an interconnector layer 15 and a fuel electrode layer 14 are present in a cylindrical solid oxide fuel cell. The interconnector layer 15 and the fuel electrode layer 14 are composed of a first air electrode molded body, a second air electrode layer molded body,
It can be formed after the simultaneous firing of the solid electrolyte layer molded body.

Specifically, a fuel electrode forming material is applied to the surface of the solid electrolyte layer obtained as described above by slurry dipping, or a sheet-like fuel made of the fuel electrode forming material manufactured by a doctor blade method. The electrode layer can be wound and baked or sintered at 1300 to 1400 ° C. in an oxidizing atmosphere to form a fuel electrode layer.

Similarly, the interconnector layer 15 is formed by applying an interconnector forming material on the second air electrode layer between both end faces of the solid electrolyte layer by slurry dipping, or by using an interconnector forming material prepared by a doctor blade method. A sheet-like interconnector molded body made of 1300-150 in an oxidizing atmosphere
Baking or sintering at 0 ° C. can form an interconnector layer.

From the viewpoint of simplifying the manufacturing process, it is desirable to form the fuel electrode layer or the fuel electrode layer and the interconnector layer simultaneously with the first air electrode, the second air electrode layer, and the solid electrolyte layer. .

Specifically, a composite sheet molded body obtained by laminating the solid electrolyte layer molded body on the second air electrode layer molded body is wound around the first air electrode molded body and laminated, and the fuel electrode is formed on the surface of the composite sheet molded body. This is a method in which layer molded bodies are laminated, an interconnector layer molded body is laminated on the exposed surface of the second air electrode layer molded body between both end faces of the solid electrolyte layer molded body, and these are simultaneously fired.

In addition, as an intermediate method between them, the first method
A cylindrical molded body composed of the air electrode molded body, the second air electrode layer molded body, the solid electrolyte layer molded body, and the interconnector layer molded body is simultaneously fired, and then the fuel electrode forming material is applied to the surface of the solid electrolyte by slurry dipping. Alternatively, a sheet-like fuel electrode layer formed body made of a fuel electrode forming material produced by a doctor blade method is attached and
The fuel electrode layer may be formed by baking at a temperature of 00 to 1400 ° C.

As a fuel electrode forming material, NiO / ZrO
₂ (containing Y ₂ O ₃ ), and a LaCrO ₃ -based composition is used as a material for forming an interconnector.
LaCrO _{3 in} which Cr is partially substituted by Mg
A system composition is preferred.

The production of the cylindrical solid oxide fuel cell is carried out from the economical point of view by adding the solid electrolyte layer molded article, the fuel electrode layer molded article, and the first air electrode molded article to the second air electrode layer molded article. It is most desirable that the connector layer molded body be co-fired.

After the composite sheet molded body is wound around the outer periphery of the first air electrode molded body and laminated, the second air electrode layer molded body and the solid electrolyte layer molded body constituting the composite sheet molded body are calcined. Is also good. In this case, handling when laminating the interconnector layer molded body and / or the fuel electrode layer molded body is facilitated.

[0037]

EXAMPLES Each of the powders is a commercially available powder having a purity of 99.9% or more and has an average crystal grain size of 10 μm as an air electrode forming material.
a _0.85 Sr _0.15 MnO ₃ powder, stabilized ZrO ₂ powder containing 10 mol% Y ₂ O ₃ having an average crystal grain size of 0.5 μm as a solid electrolyte forming material, and an average crystal grain size as a fuel electrode forming material A mixed powder of ₃ μm NiO / ZrO ₂ (containing Y ₂ O ₃ ) and a La _0.8 Ca _0.22 CrO ₃ powder having an average crystal grain size of 1 μm were prepared as interconnector forming materials.

First, a powder for extruding the above-mentioned air electrode forming powder using water as a solvent was prepared, and a hollow cylindrical first air electrode having a length of 200 mm, an outer diameter of 16 mm and an inner diameter of 11 mm was formed by an extruder. The body was made. On the other hand, the air electrode forming material and the solid electrolyte forming material were formed into sheets of various thicknesses by a doctor blade method to produce a second air electrode layer formed body and a solid electrolyte layer formed body. Similarly, a slurry was formed using water as a solvent, and a sheet-shaped interconnector layer molded article and a fuel electrode layer molded article each having a thickness of 100 μm were prepared by a doctor blade method.

Thereafter, the molded body of the solid electrolyte layer and the molded body of the second air electrode layer were joined by hydrostatic pressure molding of 0.5 (t / cm ² ) to produce a composite sheet molded body. The composite sheet molded body is wound around the cylindrical first air electrode molded body using an acrylic resin adhesive, and then the interconnector layer molded body and the fuel electrode layer molded body are laminated to form a cylindrical laminated body. A molded body was prepared, and thereafter, baked in air at 1450 ° C. for 3 hours to prepare a cylindrical solid oxide fuel cell as shown in FIG.

On the other hand, for comparison, a solid electrolyte molded body, an interconnector layer molded body and a fuel electrode layer molded body were sequentially laminated on a cylindrical molded body made of an air electrode forming material, and fired at 1450 ° C. for 3 hours in air. Was performed to produce a cylindrical solid oxide fuel cell as shown in FIG.

In any of the fuel cells manufactured as described above, the relative densities of the air electrode layer, the solid electrolyte layer, the fuel electrode layer, and the interconnector layer are 60 to 65, respectively.
%, 97-99%, 60-70%, 96-99%. The thicknesses of the solid electrolyte layer and the second air electrode layer were measured by observing the fractured surface with a scanning electron microscope, and the results are shown in Table 1.

After that, oxygen was supplied to the air electrode side and hydrogen was supplied to the fuel electrode side, and the results of power generation at 1000 ° C. are shown in Table 1. In addition, the manufacturing yield described the ratio of non-defective products when 100 pieces were manufactured. A non-defective product or a defective product was determined to be defective when the interface between the solid electrolyte layer and the air electrode was peeled off by observation with a scanning electron microscope. Table 1 shows the results.

[0043]

[Table 1]

From Table 1, it can be seen that the cylindrical solid oxide fuel cell (No. 1) of FIG. 2 having no second air electrode layer has a low output density of 0.32 W / cm ² and a high production yield. Was 73%.

On the other hand, the cylindrical solid oxide fuel cell of the present invention has an output density of 0.41 W / cm ² or more and a production yield of 88% or more, and the sample of the present invention has a good production yield. It can be seen that the power density is high.

[0046]

According to the cylindrical solid oxide fuel cell of the present invention, the bonding strength between the first air electrode and the solid electrolyte layer is improved, and the performance of the cell can be improved. Set the thickness of the solid electrolyte layer to 2
0 to 150 μm, the thickness of the second air electrode layer is 50 to 300 μm
By setting m, the joining strength between the first air electrode and the solid electrolyte layer can be further improved, and the performance of the cell can be further improved.

According to the method for manufacturing a cylindrical solid oxide fuel cell of the present invention, the cylindrical solid oxide fuel cell can be easily obtained, and the cylindrical first air electrode molded body can be obtained. Since the thickness of the composite sheet molded article to be wound can be increased, handling becomes easy, and the production yield at the time of winding can be improved.

Further, in order to laminate the solid electrolyte layer molded body on the second air electrode layer molded body in advance, and to wind and laminate the composite sheet molded body on the outer peripheral surface of the first air electrode molded body, 2 The air electrode layer molded body and the first air electrode molded body, the second air electrode layer molded body and the solid electrolyte layer molded body have good conformity, and the first air electrode molded body and the second air electrode layer molded body Since the body is made of the same air electrode forming material, the body has good conformity, and as a whole, the bonding strength between the first air electrode and the solid electrolyte layer after firing can be improved.

Further, the contact at the interface between the second air electrode layer molded body and the solid electrolyte layer molded body becomes good, and the polarization resistance caused by the poor contact can be reduced, and as a result, the power generation characteristics can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a cylindrical solid oxide fuel cell according to the present invention.

FIG. 2 is a perspective view showing a conventional cylindrical solid oxide fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... 1st air electrode 12 ... 2nd air electrode layer 13 ... Solid electrolyte layer 14 ... Fuel electrode layer 15 ... Interconnector layer

Claims (5)

[Claims] 1. A first air electrode having a cylindrical shape, a second air electrode layer formed on an outer peripheral surface of the first air electrode, and a solid electrolyte layer formed on an outer peripheral surface of the second air electrode layer. And a fuel electrode layer formed on the outer peripheral surface of the solid electrolyte layer. 2. The solid electrolyte layer has a thickness of 20 to 150 μm.
The cylindrical solid oxide fuel cell according to claim 1, wherein the thickness of the second air electrode layer is 50 to 300 m. 3. A step of producing a cylindrical first air electrode molded body made of an air electrode forming material; a step of producing a sheet-shaped second air electrode layer molded article made of said air electrode forming material; A step of producing a sheet-shaped solid electrolyte layer molded article made of an electrolyte-forming material; a step of producing a composite sheet molded article obtained by laminating the solid electrolyte layer molded article on the second air electrode layer molded article; Winding and laminating the composite sheet compact on the outer peripheral surface of the cathode compact so that the second cathode laminate is in contact with the first cathode compact; and forming the cylindrical laminate compact. And a step of firing the solid-state fuel cell. 4. A composite sheet comprising a step of producing a sheet-like fuel electrode layer molded body made of a fuel electrode forming material and a step of producing a sheet-shaped interconnector layer molded article made of an interconnector forming material. A step of laminating a fuel electrode layer molded body on the surface of the composite sheet molded body after the step of winding and laminating the molded body; and forming the exposed second air electrode layer between both end surfaces of the solid electrolyte layer molded body. Laminating the interconnector layer molded body on the surface of the body. The method for producing a cylindrical solid oxide fuel cell according to claim 3, further comprising: 5. After the step of producing the first air electrode molded body,
A step of calcining the first air electrode molded body, and the step of winding and laminating the composite sheet molded body includes, on the outer peripheral surface of the first air electrode calcined body, the composite sheet molded body,
5. The cylindrical solid oxide fuel cell according to claim 3, wherein the second air electrode layer molded body is wound and laminated so as to abut on the first air electrode calcined body. Production method.