JPH07235315A - Cylindrical solid electrolyte fuel cell - Google Patents

Abstract

PURPOSE:To reduce current collecting resistance, simplify structure, and reduce cost by performing the improvement by inclining a support tube, a fuel electrode and a part of a current collecting lead. CONSTITUTION:When cells 20a and 20b are put in a high temperature atmosphere of 1000 deg.C when a fuel cell 1 is actuated, current collecting parts 13, fuel electrodes 11 and insulating parts 12 different in materials of a fuel electrode tube 10 are heated. In joining places of the current collecting parts 13 of nickel and the insulating parts 12 of zirconia, though thermal expansions are different from each other, the same kind joining as a part of inclined parts 14a between both is performed. Thereby, the joining sides of both cause the same thermal expansion as a part of the inclined parts 14a, and do not separate from each other due to thermal fitting. The inclined parts 14a and 14e on both left and right ends abundantly contain metallic nickel in a current collecting part side boundary. Since left and right current collecting parts 13 are metallic nickel and are comparatively thickly formed as a constitutive element of the fuel electrode tube 10, resistance is very small. Since a voltage loss becomes very small by the inclined parts 14a and 14b and the current collecting parts 13, an electric current can be efficiently collected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical horizontal stripe type solid oxide fuel cell (SOFC), and more particularly to a structure of a fuel electrode tube which also serves as a current collecting means and a supporting means.

[0002]

2. Description of the Related Art In a solid electrolyte fuel cell, stabilized zirconia (YSZ), which is a solid solution of yttria in ceramic zirconia as a solid ionic conductor, is used as an electrolyte. The electrolyte layer is sandwiched between the fuel electrode and the air. And an electrode. This stabilized zirconia is 1000
At high temperatures of ° C, oxygen ions have high permeability, have almost no electronic conductivity, and do not permeate oxygen or hydrogen gas. Therefore, this property is used for the electrolyte. In this case, although the ion permeability is high compared with other methods, the solid electrolyte is formed in an extremely thin film. In this way, all of the constituent elements are solid, so that the battery structure is simplified, the electrode reaction is very active and the efficiency is improved because it operates at high temperature, and there is an advantage that a catalyst or the like is unnecessary.

On the other hand, since the solid electrolyte operates at a high temperature of 1000 ° C., the air electrode and the fuel electrode inevitably become the high temperature atmosphere, and are affected by high temperature heating, strong oxidation and reduction reaction, thermal expansion and the like. Therefore, the air electrode is required to be chemically stable in a high temperature atmosphere of oxygen, have high electronic conductivity, have good oxygen gas permeability, and have good thermal expansion matching with the electrolyte. For example, a perovskite-type lanthanum-based composite oxide is used as a material satisfying the above conditions to form a thin porous film. The fuel electrode is required to have good electron conductivity and thermal expansion matching with the electrolyte, and to have good combustion reaction with hydrogen and removal of reactants. Therefore, for example, a cermet of a mixture of metallic nickel and zirconia is used. It is formed into a thin porous membrane. Also, as the interconnector for connecting a plurality of cells, ceramics that are stable and have good conductivity in a high temperature atmosphere are used.

When a cell is actually constituted by these ceramic solid electrolytes, two electrodes, etc., for example, a mechanically supporting porous insulating support is used, and various thin films are formed on the support. It is laminated in multiple layers to form a three-layer integrated film. In the case of forming this thin film, various spraying methods, slurry methods and the like are used in order to satisfy different conditions required for each film. Further, in the case of the flat plate shape, there is a problem of gas sealing at the end portion, and therefore, a cylindrical structure is often used.

Conventionally, a cylindrical horizontal stripe type solid electrolyte fuel cell is constructed, for example, as shown in FIG. That is, the fuel cell 1 has a porous insulating tubular support tube 2 made of alumina or zirconia, and three cells 3a to 3c are arranged in series on the support tube 2, for example. That is, the fuel electrode 4 is intermittently formed of a cermet porous film of nickel and zirconia on the innermost side of the support tube 2 and is stabilized between the outer peripheral side of the fuel electrode 4 and the fuel electrodes 4. The solid electrolyte 5 made of zirconia is formed in a step shape also as an insulator. Further, an interconnector 6 is formed from the outer peripheral side of the fuel electrode 4 to the solid electrolyte 5 side, and an air electrode 7 is formed of a porous film of a composite oxide across the solid electrolyte 5 and the interconnector 6. ing. Thus cell 3a
3c are supported by the support tube 2 to form a three-layer integrated film, cells 3a to 3c are insulated from each other by the solid electrolyte 5, and electrons are passed by the interconnector 6 and connected in series.

On the other hand, current collecting leads 8a and 8b are formed of a thin film on the left and right sides of the support tube 2 which are separated from the cells 3a and 3c. In order to match the thermal expansion of the current collecting leads 8a and 8b with the support tube 2, a metal such as nickel or a cermet of nickel and zirconia is used. The positive electrode side current collecting lead 8a on the right side of the drawing is connected to the air electrode 7 of the right side cell 3a via the interconnector 6, and the negative electrode side current collecting lead 8b on the left side is connected to the fuel electrode 4 of the left side cell 3c. ing. In addition, current collecting leads 8a, 8b
The outer peripheral side of the above is covered with a gas seal layer 9, and thus the fuel cell 1 has a structure of a thin tubular shape as a whole in which three cells 3a to 3c are arranged in a horizontal stripe pattern.

Therefore, when the fuel cell 1 is in operation, the cell 3a
˜3c is set to a high temperature atmosphere of 1000 ° C. to continuously supply hydrogen as a fuel into the support tube 2 and oxygen in the air to the surroundings. Then, in the air electrode 7, oxygen reacts with the electrons flowing in the external circuit and is ionized, and the oxygen ions reach the fuel electrode 4 through the solid electrolyte 5. At the fuel electrode 4, the oxygen ions combine with hydrogen to generate electrons and water, and electricity is generated by such an electrochemical reaction. In this case, since the three cells 3a to 3c are connected in series, the total voltage obtained by adding the voltages of the three cells 3a to 3c is collected by the left and right current collecting leads 8a and 8b and taken out. .

[0008]

By the way, in the above-mentioned prior art, the current collecting leads 8a, 8b are formed of a thin film and are long. Therefore, there is a problem that the resistance of the current collecting leads 8a and 8b is increased and the voltage loss is large.

In view of the above, the present invention improves the structure of the support tube, the fuel electrode and the current collecting lead,
The purpose is to reduce current collecting resistance and simplify the structure.

[0010]

To achieve this object, the present invention is directed to a fuel collecting part, an insulating part, and a fuel electrode, which are made of different materials, which are formed in a cylindrical shape having the same diameter and are arranged in a straight line in the axial direction. A solid electrolyte and an air electrode are formed in a thin film multilayer on a concentric circle with the electrode to form a cell, and the fuel electrode is connected to a current collector on one end side in the axial direction, and the air electrode is the other end in the axial direction. A cylindrical solid oxide fuel cell connected to the current collector of the side, the intermediate part of the current collector, the insulating part and the fuel electrode of different materials, the material of the parts located on both sides of the intermediate part. An inclined portion is provided which is mixed and whose mixing ratio is inclined in the axial direction, and a current collecting portion is provided via this inclined portion.
It is characterized in that the insulating portion and the fuel electrode are sequentially joined to form a fuel electrode tube which also serves as a current collecting means and a supporting means.

Further, according to the present invention, the fuel electrode can be connected to the current collector through the inclined portion, and the air electrode can be connected to the current collector through the interconnector and the inclined portion.

Further, in the present invention, the current collecting portion may be formed of nickel metal, the insulating portion may be formed of zirconia, and the fuel electrode may be formed of cermet of nickel and zirconia.

[0013]

In the present invention having the above-described structure, the fuel electrode tube is formed by sequentially joining the current collecting portion, the insulating portion, and the fuel electrode through the inclined portion having the inclination function. When nickel, zirconia is used for the insulating part, and nickel and zirconia cermet is used for the fuel electrode, all of these components are in the state of being joined together by the inclined part.

Therefore, when the fuel electrode tube is operated in a high temperature atmosphere of 1000 ° C., the fuel electrode tube is joined to the inclined portion by the thermal expansion of the same kind of joint between the collector portion, the insulator portion and the fuel electrode which are made of different materials. It is thermally aligned to ensure a high adhesive strength, and is mechanically strong and integrally held. Therefore, it becomes possible to securely support the cell with the fuel electrode tube,
Supporting tubes are unnecessary. Further, the electricity generated in the cell is collected by the nickel-rich portion of the inclined portion of the fuel electrode tube and the nickel current collector, and the voltage loss is greatly reduced.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the overall configuration of a cylindrical horizontal stripe solid oxide fuel cell will be described. Reference numeral 1 denotes a solid electrolyte fuel cell, which has a relatively thick tubular fuel electrode tube 10, and for example, two cells 20a, 2 are provided in this fuel electrode tube 10.
0b are arranged in series. In this fuel electrode tube 10, nickel, which is a metal having good conductivity, is used as the current collecting portion 13, zirconia having good insulating properties is used as the insulating portion 12, and cermet of nickel and zirconia is used as the fuel electrode 11 of the porous membrane. used. Current collector 1 made of different materials
3, the insulating portion 12 and the fuel electrode 11 are formed in a cylindrical shape having the same diameter and are arranged on a straight line in the axial direction as shown in FIG. 1, so that they can serve both as a collector and a support.

Here, the current collecting portion 13 and the insulating portion 1 made of different materials are used.
Simply joining 2 and the fuel electrode 11 results in joining different materials. Therefore, in a high temperature atmosphere of 1000 ° C,
Due to the difference in thermal expansion at the joint, thermal mismatch occurs and peeling occurs. Therefore, the fuel electrode tube 1 in this high temperature atmosphere
In order to strengthen the mechanical properties by thermally matching at the joints of different materials of 0, the first to the 5th joints of the two current collecting portions 13, the insulating portions 12 and the fuel electrodes 11 are formed respectively. Fifth inclined portions 14a to 14e are provided.

The first sloping portion 14a on the rightmost side of the drawing is a joint portion of the insulating portion 12 of zirconia and the current collecting portion 13 of nickel, so that both zirconia and nickel materials are mixed. As shown in FIG. 2, the mixing ratio of these materials is about 100% nickel at the boundary of the current collecting portion side, and the current collecting portion 13
The same type of zirconia is bonded at the boundary of the insulating part.
%, It changes in the axial direction and is inclined so as to join the insulating portion 12 with the same kind. Since the second inclined portion 14b is a joint portion between the fuel electrode 11 of the cermet of nickel and zirconia and the insulating portion 12 of zirconia, nickel and zirconia are mixed, and the mixing ratio thereof is as shown in the figure. At the boundary, zirconia is approximately 100%, and at the boundary on the fuel electrode side, the composition ratio is the same as that of cermet.

The third and fourth inclined portions 14c and 14d are inclined similarly to the second inclined portion 14b. Since the leftmost fifth inclined portion 14e is the joint between the nickel current collector 13 and the cermet fuel electrode 11, nickel and zirconia are mixed, and the mixing ratio is the same as that of cermet at the fuel electrode side boundary. In the blending ratio, nickel is graded to about 100% at the boundary on the current collector side. The tilting function of these tilted portions 14a to 14e is, for example, when a thermal spraying method is used, by controlling the blending ratio at the time of material supply at the time of molding the tilted portion, the blending ratio in the axial direction can be arbitrarily changed to make the tilt. can do.

In this way, the current collecting portion 13, the insulating portion 12 and the fuel electrode 11 which are made of different materials of the fuel electrode tube 10 are all aligned in a straight line by the inclined portions 14a to 14e in the joined state of the same material as shown in FIG. Joined and integrated. Further, since the metallic nickel is contained in all the inclined portions 14a to 14e, the conductivity is improved, and therefore the inclined portion 14a is formed.
It becomes possible to use ~ 14e in an electric circuit.

Next, the structure of the cells 20a and 20b will be described. In the first cell 20a, a solid electrolyte 21 made of stabilized zirconia is formed on the outer peripheral side of the fuel electrode 11 and the inclined portion 14b. Further, a ceramic interconnector 23 which is stable and has good conductivity in a high temperature atmosphere is formed on the outer peripheral side of the inclined portion 14a and the insulating portion 12. Further, a porous membrane air electrode 22 made of a complex oxide is formed on the outer peripheral side of the solid electrolyte 21 and the interconnector 23 to substantially form a three-layer integrated membrane. Further, the second cell 20b has the same solid electrolyte 21 on the outer peripheral side of the fuel electrode 11 and the inclined portion 14d.
The same interconnector 23 is formed on the outer peripheral side of the inclined portion 14c and the insulating portion 12. The same air electrode 22 is formed on the outer peripheral side of the solid electrolyte 21 and the interconnector 23 to form a three-layer integrated film. Further, the outer peripheral sides of the nickel current collectors 13 at the left and right ends are covered with a gas seal layer 24.

Thus, the two cells 20a and 20b are provided on the outer peripheral side of the fuel electrode tube 10 so as to be mechanically supported. The cells 20a and 20b are insulated from each other by the insulating part 1.
It is insulated by 2, and is connected in series by the interconnector 23 and the third inclined portion 14c. The air electrode side of the first cell 20a is connected to the interconnector 23 and the first inclined portion 1
4a is connected to the right side current collecting part 13, and the fuel electrode side of the second cell 20b is connected to the left side current collecting part 13 by the fifth inclined part 14e. Therefore, the fuel cell 1 has a structure in which two cells 20a and 20b are arranged in a horizontal stripe pattern in a thin tubular shape as a whole.

Next, the operation of this embodiment will be described. First, when the cells 20a and 20b are subjected to a high temperature atmosphere of 1000 ° C. during the operation of the fuel cell 1, the current collecting portion 13, the fuel electrode 11 and the insulating portion 12 made of different materials of the fuel electrode tube 10 are heated to a high temperature. Therefore, for example, the joint portion between the nickel current collector 13 and the zirconia insulating portion 12 has different thermal expansions, but both the current collector 13 and the insulating portion 12 have a sloped portion 14a between them. It is the same kind of joint as the department. Therefore, the joint side between the current collecting portion 13 and the insulating portion 12 is thermally expanded and thermally matched in the same manner as a part of the inclined portion 14a, and thus a large adhesive strength is achieved without peeling or the like even in the high temperature atmosphere. Reserved.

In the same manner, the sloped portions 14b to 14b are also formed at other joints of the current collector 13, the fuel electrode 11 and the insulator 12.
14e provides thermal bonding in a high temperature atmosphere and ensures a high adhesive strength. Therefore, the fuel electrode tube 1 in a high temperature atmosphere
No. 0 is held in a state where the current collector 13, the fuel electrode 11, and the insulating portion 12 made of different materials are firmly joined together, and the fuel electrode tube 10 reliably supports the two cells 20a, 20b.

Then, when hydrogen or the like of the fuel is continuously supplied to the inside of the fuel electrode tube 10 and oxygen in the air is continuously supplied to the surroundings, an electrochemical reaction is caused in each of the two cells 20a and 20b insulated by the insulating portion 12. To do. That is, the air electrode 2 in a high temperature atmosphere
In 2, oxygen is actively reacted with the electrons flowing in the external circuit and ionized, and the ions pass through the solid electrolyte 21 of stabilized zirconia in a high temperature atmosphere due to its characteristics. Then, in the fuel electrode 11, the oxygen ions that have passed through the solid electrolyte 21 are actively combined with hydrogen, and a combustion reaction is generated so as to generate electrons and water to generate electricity. At this time, the two cells 20a, 20b
The voltage generated at 1 is added by the serial connection of the interconnector 23 and the third inclined portion 14c, and this total voltage is added to the interconnector 23 and the inclined portions 14a, 1 at the left and right ends.
Current is collected by the current collector 13 via 4e.

In this case, the inclined portions 14a, 1 at the left and right ends
4e contains a large amount of metallic nickel at the boundary on the current collector side. Further, the left and right current collectors 13 are made of nickel metal and are formed relatively thick as constituent elements of the fuel electrode tube 10, so that the resistance is very small. Therefore, these inclined portions 14
Power is efficiently collected by a and 14e and the current collector 13 with a very small voltage loss.

The embodiments of the present invention have been described above. The materials of the current collecting portion, the insulating portion and the fuel electrode of the fuel electrode tube,
Of course, when the arrangement is different, the same can be applied to the case where other components are added.

[0027]

As described above, according to the present invention, in a cylindrical solid electrolyte fuel cell, a current collecting part, an insulating part and a fuel electrode made of different materials are joined to each other,
A configuration is provided in which a sloped portion is provided in which both materials are mixed and the mixing ratio thereof is inclined in the axial direction, and the current collector, the insulating portion, and the fuel electrode are sequentially joined via the sloped portion to form a fuel electrode tube. Therefore, it is possible to thermally align all the joints in a high temperature atmosphere to form a mechanically strong fuel electrode tube.
In addition, since the inclined portion of the fuel electrode tube having a large amount of metal and the metal current collecting tube collect current, the current collecting resistance can be greatly reduced. Further, since the cells are directly supported by the fuel electrode tube, a supporting tube or the like is not required, and the structure is greatly simplified. Due to the simplification of the structure, the manufacturing time can be shortened and the cost can be reduced. And since the fuel electrode tube is made of materials centered on metal,
An effect such as cost reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a cylindrical solid electrolyte fuel cell according to the present invention.

FIG. 2 is a diagram showing a material distribution state of a fuel electrode tube.

FIG. 3 is a cross-sectional view showing a conventional cylindrical horizontal stripe solid oxide fuel cell.

[Explanation of symbols]

1 ... Cylindrical solid electrolyte fuel cell, 10 ... Fuel electrode tube,
11 ... Fuel electrode, 12 ... Insulating part, 13 ... Current collecting part,
14a, -14e ... inclined part, 20a, 20b ... cell,
21 ... Solid electrolyte, 22 ... Air electrode.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Satoru Yamaoka 1-5-1 Kiba, Koto-ku, Tokyo Fujikura Ltd. (72) Inventor Mikiyuki Ono 1-1-5 Kiba, Koto-ku, Tokyo Shares Inside Fujikura

Claims (3)

[Claims] 1. A current collecting portion, an insulating portion, and a fuel electrode made of different materials are formed in a cylindrical shape having the same diameter and arranged in a straight line in the axial direction, and a solid electrolyte and an air electrode are formed in a thin film multilayer on a concentric circle with the fuel electrode. Cylindrical solid electrolyte fuel whose fuel electrode is connected to the current collector on one end side in the axial direction and whose air electrode is connected to the current collector on the other end side in the axial direction In the battery, an inclined portion in which the materials of portions located on both sides of the intermediate portion are mixed with each other in the intermediate portion of the current collecting portion, the insulating portion, and the fuel electrode of different materials, and the mixing ratio thereof is inclined in the axial direction is provided. A cylindrical solid electrolyte fuel cell, characterized in that a fuel electrode tube serving as a current collecting means and a supporting means is formed by sequentially connecting the current collecting section, the insulating section and the fuel electrode through the inclined section. 2. The fuel electrode is connected to the current collector via an inclined portion, and the air electrode is connected to the current collector via an interconnector and an inclined portion. The cylindrical solid electrolyte fuel cell described in 1 .. 3. The cylindrical solid electrolyte fuel cell according to claim 1, wherein the current collecting portion is metallic nickel, the insulating portion is zirconia, and the fuel electrode is a cermet of nickel and zirconia.