JP4781823B2 - Cylindrical horizontal stripe fuel cell - Google Patents

Description

  The present invention relates to a method for manufacturing a cylindrical horizontal stripe solid electrolyte fuel cell (SOFC).

  A cylindrical horizontal stripe type solid electrolyte fuel cell (SOFC, hereinafter also referred to as “cylindrical horizontal stripe type fuel cell”) has a power generation single element made of a functional film formed in a stripe shape on the surface of a cylindrical base tube. A plurality (N) are arranged.

FIG. 18 shows an outline of a base tube of a thermal spray type solid oxide fuel cell. As shown in FIG. 18, a thermal spray type solid oxide fuel cell (SOFC) includes a base tube 1 of a calcia-stabilized zirconia (CSZ) porous cylindrical tube, Ni and yttria-stabilized zirconia (YSZ) as a fuel electrode 2. A cermet is formed by plasma spraying. Next, an oxygen ion conductive YSZ is formed thereon as an electrolyte film 3 by plasma spraying. Thereafter, a LaCoO ₃ film is formed thereon as an air electrode 4 by acetylene flame spraying to constitute a fuel cell. Finally, the fuel electrode 2 and the air electrode 4 are connected in series by a conductive connecting material (interconnector) 5 formed of NiAl and alumina cermet. In addition, the code | symbol 6 has illustrated the central axis (patent document 1).

JP 2000-106192 A

By the way, a power generation device using a cylindrical horizontal stripe type fuel cell is composed of a plurality (100 to 200) of the cylindrical horizontal stripe type fuel cells. However, there is a demand for downsizing and cost reduction of the device. Yes.
Therefore, an increase in the output of one cell tube is eagerly desired.

  By the way, in order to increase the output of one cell tube, the resistance of the material itself and the electrochemical reaction resistance are lowered, and the cell structure (size) is optimized (the number of elements N is optimized and the element length is optimized). However, the present situation is that no suitable fuel cell has yet appeared.

  In view of the above problems, an object of the present invention is to provide a cylindrical horizontal stripe fuel cell capable of increasing the output of one cell tube.

A first invention of the present invention for solving the above-described problem is a cylindrical horizontal stripe fuel cell in which a plurality of functional films are formed in a horizontal stripe shape at a predetermined interval on the surface of a cylindrical substrate tube, and the electrolyte Two different types of functional films interposing a film are stacked and formed in a plurality of horizontal stripes offset from the base end side, and the outermost functional film and the innermost functional film are electrically connected. The interconnector to be connected to each other constitutes one unit of a striped cell, and the effective power generation part (X) of each cell of the functional film , and the offset inter-element part (L ) Is a relationship of X / L = 1 to 2 and the overall cell length / cell length of the base tube is 40 cells or more .

  According to a second aspect of the invention, there is provided the cylindrical horizontal stripe type fuel cell according to the first aspect, wherein the innermost functional film is a fuel electrode and the outermost functional film is an air electrode.

  According to a third aspect of the invention, there is provided the cylindrical horizontal striped fuel cell according to the first aspect, wherein the innermost functional film is an air electrode and the outermost functional film is a fuel electrode.

According to a fourth aspect of the present invention, there is provided a fuel electrode formed in a horizontal stripe shape with a predetermined interval on the surface of a cylindrical base tube, and a surface of the fuel electrode at a terminal end in an axial direction from the base end side of the base tube. The horizontal stripe-shaped electrolyte is formed while connecting the electrolyte having the horizontal stripe shape and the electrolyte that is formed in a horizontal stripe shape while being offset toward the end portion side of the fuel electrode and is in contact with the base tube. An interconnector that covers the base end side of the fuel electrode, and is formed on the surface of the electrolyte in the form of a horizontal stripe while offset from the base end side of the base tube 1 toward the terminal end in the axial direction. A plurality of horizontally-striped cells comprising an air electrode covering a part of the air electrode, and an effective power generation unit (X) of each cell of the air electrode , a fuel electrode, an electrolyte membrane, The offset element-to-element part (L) is in the relationship of X / L = 1 to 2 In addition, there is a cylindrical horizontal stripe fuel cell characterized in that the total cell length of the base tube / cell length = 40 cells or more .

A fifth aspect of the present invention is the length according to the second aspect, wherein the effective power generation part (X) is in contact with the air electrode and the electrolyte from the base end part of the air electrode of the first cell, Cylindrical horizontal stripe characterized in that the inter-element portion (L) is a length between the base end portion of the second fuel electrode of the second cell and the base end portion of the second electrolyte. Type fuel cell.

  According to the present invention, the output of one cell tube can be increased, and the power generator can be reduced in size and cost.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

A cylindrical horizontal stripe fuel cell according to Example 1 of the present invention will be described with reference to the drawings.
1 is a conceptual diagram illustrating a cylindrical horizontal stripe fuel cell according to a first embodiment.
As shown in FIG. 1, a cylindrical horizontal stripe fuel cell 10 according to this embodiment includes fuel electrodes 12-1, 12-2, 12-12 formed in a horizontal stripe pattern with a predetermined interval on the surface of a cylindrical base tube 11. (Hereinafter, it may be described as “12” in some cases.) And terminates in the axial direction from the base end side of the base tube 11 on each surface of the fuel electrodes 12-1, 12-2. Are formed in horizontal stripes while being offset toward the portion, and the end portions 13e of the fuel electrodes 12-1, 12-2,. The electrolytes 13-1, 13-2 (which may be referred to as “13” hereinafter) and the horizontally striped electrolytes 13-1, 13-2 are connected to each other. Interconnectors 15-1, 15-2 that cover the base end sides of the fuel electrodes 12-1, 12-2 (note that .., And offset from the base end side of the base tube 11 toward the end portion in the axial direction on the surfaces of the electrolytes 13-1, 13-2. However, the air electrodes 14-1, 14-2,... (Hereinafter referred to as “symbols”) are respectively formed in a horizontal stripe shape and cover a part of each interconnector 15-1, 15-2 on the terminal end side. 14 ”, and a plurality of horizontally-striped cells 16-1, 16-2,... Formed in the axial direction, and an effective power generation unit X of each cell. The offset inter-element portion L of each cell has a relationship of X / L = 0.5-5.

  Here, in this embodiment, the base end portion of the cylindrical horizontal stripe type fuel cell is illustrated, and as shown in FIG. 17 described above, the cells are formed in a plurality of stripes over the terminal end side. Although not shown in the figure. Here, when counting the number of a plurality of provided cells, they are expressed as a first cell 16-1, a second cell 16-2,. Further, as will be described later, the cell length represents a portion where electricity flows between the first cell and the second cell.

  In the first cell 16-1, the effective power generation unit X in the present invention is defined by the air electrode 14-1, the electrolyte 13-1, and the base electrode 14-1a. Is the length of contact with the entire surface.

  In the present invention, the inter-element portion L means, in the first cell 16-1, the base end portion 12-1a of the first fuel electrode 12-1 and the base of the first electrolyte 13-1. This is an offset length between the end portion 13-1a.

Moreover, the cell length Y in the present invention, first a base end portion of the air electrode 14-1 14-1a of the first cell 16-1, the second electrolyte of the second cell 16-2 13 -2 to the base end portion 13-2a.

  Here, the base tube 11 is made of, for example, calcia-stabilized zirconia (CSZ), has an outer diameter of 10 mm to 30 mm, and a thickness of 0.5 to 4 mm, more preferably 0.5 to 3 mm.

  The fuel electrode 12 is made of, for example, a mixture of Ni and yttrium stabilized zirconia (YSZ) and has a thickness of 20 to 300 μm, more preferably 50 to 200 μm.

  Moreover, the electrolyte 13 consists of YSZ etc., for example, The thickness is 5-80 micrometers, More preferably, it is 10-50 micrometers.

The air electrode 14 is made of, for example, LaMnO ₃ , LaCoO ₃ , LaCaMnO _3, etc., and has a thickness of 1000 to 2000 μm.

The interconnector 15 is made of, for example, a perovskite oxide such as SrTiO ₃ , LaCrO ₃ or the like, and has a thickness of 5 to 50 μm.

Then, the substrate tube 11 of the example 1000 mm, placing the unit cells of the cell length Y in series. The length of the base tube 11 is not limited to 1000 mm.

[Test Example 1 to Test Example 3]
Hereinafter, the relationship between the effective power generation portion X, the inter-element portion L, and the output (W) / line when the cell is mounted using the base tube 11 of 1000 mm is shown.
Figure 1 is a LaMnO ₃ used as an air electrode 14, a SrTiO ₃ is used as interconnectors 15, fuel pole 12 ... are, for example, when using the mixture of Ni and yttrium-stabilized zirconia (YSZ) The number of cells is 20 cells (Y = 5), 30 cells (Y = 3.3), 40 cells (Y = 2.5), 50 cells (Y = 2), and 60 cells (Y = 1.7). ), The output per cell when 70 cells (Y = 1.5) were measured.

Table 1 shows the conductivity. The test results are shown in FIG.
As shown in FIG. 2, since the conventional cell is about 100 W, it was found that in the case of 30 cells, it exceeds 100 W / line in the case of 0.5 ≦ X / L <3. In addition, in the case of 30 cells or more, it was found that when 0.5 ≦ X / L ≦ 5, it exceeded 100 W / line.
In addition, when the material was changed as in Test Example 2 and Test Example 3, it was found that the output was further improved over the conventional 100 W / line in all cases of 30 cells or more.

The relationship between the number of cells and the maximum output in FIG. 5 shows the relationship between the cell length Y and the maximum output in FIG.
The results of these figures, the number of cells is 50 to 60 cells, and found that the cell length Y be 1.7 position is maximum, the maximum output be too much the number of cells (short cell length is) It turned out not to increase.

As a result, as shown in FIGS. 2 to 4, in 30 cells (Y = 2.5) or more, X / L is 0.5 to 5, more preferably, X / L is in the range of 0.5 to 3. The output per one became 100 W or more, and high output could be achieved.
Moreover, it was confirmed that the output was further improved when a highly conductive air electrode or interconnector was used as the air electrode.

Further, in the above 60 elements, the output also to shorten the cell length Y was found not improved.
Therefore, in the case of 1000 mm, 60 elements is the maximum, and in the case of mass production, it is preferable to set it to 50 elements or less.

From any of the test examples, it was found that the maximum output ( effective power generation part X / element-to-element part L) is more preferably about 1-2.

Next, an example of a method for producing a cylindrical horizontal stripe fuel cell according to the present invention will be described.
First, an organic solvent (including an additive) is mixed with a well-ground ceramic powder for base tube to form a uniform slurry.
Next, the slurry is put into an extrusion molding machine, and a tubular ceramic molded body is produced by extrusion. For example, with respect to the tube length, if a 20% shrinkage is expected as a whole, a ceramic molded body of 1250 mm is produced when the length of the sintered body (target length) is 1000 mm. The ceramic molded body that becomes the base tube is dried at, for example, 50 to 200 ° C. in a drying furnace.

Subsequently, a paste-like fuel electrode material is applied by screen printing onto an unfired ceramic molded body and dried at, for example, 50 to 200 ° C. in a drying furnace. The fuel electrode material is printed on the outer periphery of the ceramic molded body in a striped pattern with a certain width in the longitudinal direction to form a fuel electrode.
At this time, offset printing is performed so that the effective power generation unit X / inter-element portion L is approximately in the vicinity of 1-2.
Next, a paste-like electrolyte material is applied thereon (screen printing) and dried in a drying furnace at, for example, 50 to 200 ° C. to obtain an electrolyte. Here, the electrolyte is offset to the fuel electrode of a predetermined length and printed in a striped pattern.
Subsequently, a paste is formed on the electrolytes 13-1, 13-2,... Printed at predetermined intervals so that the first electrolyte and the second fuel electrode are connected by the first interconnector. The interconnector material (lanthanum chromite) is applied in layers (screen printing) and dried at about 50 to 200 ° C. in a drying furnace to form an interconnector.

  Thereafter, the ceramic molded body that has been coated and dried is set in a firing furnace in order to fire. The temperature is raised to a holding temperature (1200 to 1400 ° C.) at a predetermined rate of temperature rise. When the holding temperature is reached, the temperature is held for an appropriate time.

  Next, an air electrode material is layered on the electrolyte 13 printed at a predetermined interval and applied (screen printing), and dried at, for example, 50 to 200 ° C. in a drying furnace to form an air electrode. Here, the air electrode is offset to an electrolyte of a predetermined length and printed in a striped pattern.

  Thereafter, the ceramic formed body after the application and drying of the air electrode is set in a firing furnace for firing. The temperature is raised to a holding temperature (1200 to 1700 ° C.) at a predetermined rate of temperature rise. Then, when the holding temperature is reached, the temperature is held for an appropriate time, and the ceramic molded body is sintered for a predetermined time, and then cooled to obtain a cylindrical horizontal stripe fuel cell.

  In addition, although the manufacturing method mentioned above is a two-stage baking method, this invention is not limited to this, It is good also as a one-stage baking method.

[Reference Example 1]
Next, Reference Example 1 of the present invention will be described. FIG. 7 is a schematic view of a cylindrical horizontal stripe fuel cell of this reference example.
In this reference example, as shown in FIG. 7, the air electrode 14 is a mixture of two different particle sizes of coarse particles 30 and fine particles 31, and the porosity is reduced as compared with the conventional coarse particles 30 alone. Thus, the adhesion with the interconnector is improved.

First, the fine particles 31 of the air electrode are those having an average particle size of 5 μm, and the coarse particles 30 are those having 10 μm particles, 20 μm particles, 40 μm particles, 50 μm particles, and 60 μm particles to adjust the slurry, Baked in air for hours.
The result is shown in FIG. From the results of FIG. 8, it was found that the porosity is good when the mixing rate is 0.2 to 0.8 in the combination of coarse particles and fine particles of 20 μm or more.

Further, the fine particles 31 of the air electrode are those having an average particle diameter of 1 μm, and the coarse particles 30 are those of 10 μm particles, 20 μm particles, 40 μm particles, 50 μm particles, and 60 μm particles, and the slurry is adjusted to obtain 1300 ° C., 3 μm. Baked in air for hours.
The result is shown in FIG. From the results shown in FIG. 9, it was found that in the combination of coarse particles and fine particles of 10 μm particles or more, when the mixing rate is 0.2 to 0.8, the porosity is very good at 0.2 or less.

The combination of the average particle size of 50 μm and the average particle size of 5 μm has a porosity of about 0.2 (Test Example 4), and the combination of the average particle size of 10 μm and the average particle size of 5 μm has a porosity of about 0.1. The voltage between the interconnector 15 and the air electrode 14 with three (Comparative Example 1) was measured.
The result is shown in FIG.
As shown in FIG. 10, it is expected that the lower the voltage between the interconnector 15 and the air electrode 14, the more the cell output is improved by about 10%.

  Further, the improvement in densification due to the porosity is not limited to the combination of two types of materials, but as a mixture of three different particle sizes of coarse particles and fine particles, and intermediate particles composed of coarse particles and fine particles. Also good. As a result, the tightly packed structure is strengthened, and the contact area (number of contact points) between the interconnector and the air electrode is further increased.

FIG. 11 shows a mixture of particles of 50 μm, 5 μm, and 1 μm. 50 μm coarse particles are fixed to 50% by volume, 60% by volume, and 70% by volume, and the particle mixing ratio of 1 μm and 5 μm is changed in each. It was.
The result is shown in FIG. As shown in FIG. 11, a three-component system in which coarse particles of 50 μm are 70% by volume has a low porosity and good results. In particular, it was found that the void ratio was 0.09 when 50 μm was 70% by volume, 5 μm was 5% by volume, and 1 μm was 25% by volume.

[Reference Example 2]
Next, Reference Example 2 of the present invention will be described. FIG. 12 is a schematic view of a cylindrical horizontal stripe fuel cell of this reference example.
In this reference example, as shown in FIG. 12, a diffusion prevention layer 21 is interposed between the air electrode 14 and the interconnector 15, and the diffusion prevention layer 21 is used to connect to the interconnector 15. The diffusion of the air electrode 14 material is prevented.
In particular, in the case of LaCaMnO ₃ containing a Ca component as the air electrode 14, a diffusion preventing layer 21 such as LaSrMnO 3 not containing a Ca component that prevents the Ca component from diffusing is provided.

The thickness of the diffusion preventing layer 21 may be 20 to 30 μm.
As a result, the Ca component contained in the air electrode 14 is prevented from diffusing into the interconnector 15, and power can be stably generated over a long period of time.

[Reference Example 3]
Next, Reference Example 3 of the present invention will be described. FIG. 13 is a schematic view of a cylindrical horizontal stripe fuel cell of this reference example.
In this reference example, as shown in FIG. 13, an intermediate layer 22 is provided between the electrolyte 13 and the fuel electrode 12.
The intermediate layer 22 may be an oxide such as CeO ₃ or TiO ₃ .
Since the intermediate layer 22 is made of an oxide such as CeO ₃ or TiO ₃ , electron conductivity is generated in addition to oxygen ion conductivity in a reducing atmosphere, and so-called mixed conductivity is exhibited.

  Then, by providing the intermediate layer 22 between the fuel electrode (electron conductivity) 12 and the electrolyte (oxygen ion conductivity) 13, the transfer of electrons and oxygen ions between the fuel electrode 12 and the electrolyte 13 is more effective. To be done. As a result, the contact resistance at the interface between the fuel electrode 12 and the electrolyte 13 is reduced.

  Further, in the electrolyte, a 2 μm to 5 μm projection made of the same material as the electrolyte may be provided on the surface, or the electrolyte may have a concavo-convex structure.

FIG. 14 shows the current-voltage characteristics evaluated in a hydrogen and water vapor atmosphere as a pellet test. A fuel electrode made of Ni and YSZ was formed on the surface of a YSZ pellet, and an intermediate layer 22 made of an oxide of CeO ₃ was interposed between them.
As shown in FIG. 14, it was found that the test example 5 in which the intermediate layer 22 is interposed reduces the contact resistance as compared with the comparative example 2 in which the intermediate layer 22 is not interposed.

[Reference Example 4]
Next, Reference Example 4 of the present invention will be described. FIG. 15 is a schematic view of a cylindrical horizontal stripe fuel cell of this reference example.
In this reference example, as shown in FIG. 15, an electrolyte protrusion 23 is formed on the surface of the electrolyte 13, and an air electrode 14 is formed on the protrusion 23.
In addition, it is not limited to the protrusion 23, It is good also as an unevenness | corrugation.

  In the case of forming the protrusions 23 and the like, after the electrolyte 13 having a predetermined thickness is formed, a slurry containing 2 μm to 5 μm ceramic of the same material as the electrolyte 13 is further printed and fired to form the protrusions 23. I am trying to provide it.

  FIG. 16 shows the voltage drop of the element portion when the protrusion is formed (Test Example 6) and when the protrusion is not formed (Comparative Example 3). Since the contact area is increased by forming the protrusion 23, it was confirmed that it contributes to the voltage effect.

  As described above, the cylindrical horizontal stripe fuel cell according to the present invention can increase the output of one cell tube, and is suitable for improving the cell output of the fuel cell.

1 is a schematic view of a cylindrical horizontal stripe fuel cell according to Example 1. FIG. It is a figure which shows the relationship between the element length / element length of a test example 1, and an output. It is a figure which shows the relationship between the element length / element length of Test Example 2, and an output. It is a figure which shows the relationship between the element length / element length of a test example 3, and an output. It is a figure which shows the relationship between the cell number of Test Examples 1-3, and an output. It is a figure which shows the relationship between the cell length of Test Examples 1-3, and an output. 2 is a schematic view of a cylindrical horizontal stripe fuel cell according to Reference Example 1. FIG. It is a figure which shows the relationship between the mixing rate of two components (coarse grain and fine grain (average particle diameter of 5 micrometers)) and the porosity which concern on the reference example 1. FIG. It is a figure which shows the relationship between the mixing rate and the porosity of the coarse grain and fine grain (average particle diameter of 5 micrometers) which concern on the reference example 1. FIG. It is a figure which shows the relationship of the voltage between the air electrode which concerns on the test example 4 and the comparative example 1, and an interconnector. It is a figure which shows the relationship between the mixing ratio and the porosity of the three components (coarse particles and fine particles (average particle diameter 1 μm, 5 μm)) according to Reference Example 1 . 6 is a schematic view of a cylindrical horizontal stripe fuel cell according to Reference Example 2. FIG. 10 is a schematic view of a cylindrical horizontal stripe fuel cell according to Reference Example 3. FIG. It is a figure which shows the relationship of the voltage between the air electrode which concerns on Test Example 5 and Comparative Example 2, and an interconnector. 6 is a schematic view of a cylindrical horizontal stripe fuel cell according to Reference Example 4. FIG. It is a figure which shows the relationship of the voltage between the air electrode which concerns on the test example 6 and the comparative example 3, and an interconnector. 1 is a schematic view of a cylindrical tube fuel cell. 1 is a schematic configuration diagram of a fuel cell.

11 substrate tube 12 the fuel electrode 13 electrolyte 14 air electrode 15 interconnector X between the effective power generation unit L element Y cell length

Claims (5)

A cylindrical horizontal stripe type fuel cell in which a plurality of functional films are formed in a horizontal stripe shape at a predetermined interval on the surface of a cylindrical substrate tube,
Two kinds of different functional films formed by interposing an electrolyte film are stacked and formed in a plurality of horizontal stripes while offset from the base end side,
The outermost layer functional film and the interconnector that electrically connects the innermost layer functional film constitute one striped cell unit, and an effective power generation unit (X) of each cell of the functional film; And the offset inter-element portion (L) of two different functional films,
X / L = 1-2
As well as a relationship,
A cylindrical horizontal stripe type fuel cell characterized in that the total cell length of the base tube / cell length = 40 cells or more . In claim 1,
A cylindrical horizontal stripe type fuel cell, wherein the innermost functional film is a fuel electrode and the outermost functional film is an air electrode. In claim 1,
A cylindrical horizontal stripe type fuel cell, wherein the innermost functional film is an air electrode and the outermost functional film is a fuel electrode. A fuel electrode formed in a horizontal stripe pattern at a predetermined interval on the surface of a cylindrical base tube;
The surface of the fuel electrode is formed in a horizontal stripe shape while being offset from the base end side of the base tube in the axial direction toward the terminal end, and the end of the fuel electrode is covered with the base end. An electrolyte in contact with the tube;
An interconnector that covers the base end side of the horizontal stripe fuel electrode while connecting the horizontal stripe electrolytes;
A horizontally striped cell formed on the surface of the electrolyte, having a horizontal striped shape, offset from the base end side of the base tube toward the terminal end in the axial direction, and an air electrode covering a part of the interconnector Are formed in the axial direction,
and,
The effective power generation part (X) of each cell of the air electrode, and the inter-element part (L) offset between the fuel electrode and the electrolyte membrane ,
X / L = 1-2
As well as a relationship,
A cylindrical horizontal-striped fuel cell characterized in that the total cell length of the substrate tube / cell length = 40 cells or more . In claim 2,
Effective power generation part (X)
From the base end of the air electrode of the first cell, the air electrode and the electrolyte are in contact with each other,
The inter-element portion (L) is
A cylindrical horizontal stripe type fuel cell having a length between a base end portion of a second fuel electrode of the second cell and a base end portion of the second electrolyte.

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