JP3487630B2 - Cylindrical solid electrolyte fuel cell - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolyte fuel cell (SOFC) having a cylindrical vertical stripe shape, and more particularly, to a structure of a fuel electrode tube serving both as a current collecting means and a supporting means. It is about. 2. Description of the Related Art A solid electrolyte fuel cell uses a stabilized zirconia (YSZ) in which yttria is dissolved in ceramic zirconia as a solid ionic conductor as an electrolyte, and a fuel electrode is sandwiched between the electrolytes. And an air electrode. This stabilized zirconia has a temperature of 1000 ° C.
When the temperature becomes high, the permeability of oxygen ions becomes high, and there are characteristics such as almost no electronic conductivity and no permeation of oxygen or hydrogen gas. Therefore, these characteristics are used for the electrolyte. In this case, the solid electrolyte is formed in an extremely thin film because the ion permeability is high but low as compared with other methods. In this way, since all the components are solid, the battery structure is simplified, and since the battery operates at a high temperature, the electrode reaction is very active and the efficiency is improved. On the other hand, since the solid electrolyte operates at a high temperature of 1000 ° C., the air electrode and the fuel electrode necessarily have a high-temperature atmosphere, and are affected by high-temperature heating, strong oxidation and reduction reactions, thermal expansion, and the like. Therefore, the air electrode is required to be chemically stable in a high-temperature atmosphere of oxygen, to have high electron conductivity, to have good oxygen gas permeability, and to have good thermal expansion matching with the electrolyte. A thin porous film is formed using, for example, a perovskite-type lanthanum-based composite oxide as a material satisfying the above conditions. The fuel electrode is required to have good electron conductivity and good thermal expansion matching with the electrolyte, good combustion reaction with hydrogen and removal of reactants, and so on.For example, a cermet of a mixture of metal nickel and zirconia is required. Used to form a thin porous membrane. Ceramics that are stable and have high conductivity in a high-temperature atmosphere are also used as interconnectors for connecting a plurality of cells. When a cell is actually constituted by a solid electrolyte of these ceramics, two electrodes, etc., for example, a porous insulating support which is mechanically supported is used, and various thin films are formed on the support. It is formed as a three-layer integrated film by laminating a plurality of layers. In the case of thin film formation, various thermal spraying methods, slurry methods, and the like are used to satisfy different conditions required for each film. Further, in the case of a flat plate shape, there is a problem of gas sealing at an end portion, so that a cylindrical structure is often used. Conventionally, a solid electrolyte fuel cell having a cylindrical vertical stripe shape is constructed as shown in FIG. 3, for example. That is, the fuel cell 1 has a porous insulating tubular support tube 2 using alumina or zirconia, and a single cell 3 that is long in the axial direction is arranged on the support tube 2. That is, an air electrode 4 of a composite oxide porous film is formed on the innermost part of the support tube 2, and a stabilized zirconia solid electrolyte 5 is formed on the outer peripheral side of the air electrode 4. A fuel electrode 6 of a porous membrane of cermet of nickel and zirconia is formed on the outermost side, and is formed as a three-layer integrated membrane. Further, in order to form an external circuit by collecting current, an interconnector 7 made of ceramics having good conductivity is formed on the entire outer peripheral portion of the air electrode 4 in the axial direction so as to be exposed to the outside. And the outermost fuel electrodes 6 are brought into contact with the metal current collectors 8, 9, respectively. Then, they are connected to the fuel electrode 6 'and the interconnector 7' of the other cells by the metal current collectors 8, 9, respectively. In this manner, the fuel cell 1 has a structure in which the cells 3 are arranged in a thin tubular shape and the cells 3 are arranged in a vertical stripe pattern. Therefore, when the fuel cell 1 is operated, the cell 3 is kept at a high temperature of 1000 ° C. to continuously supply oxygen in the air into the inside of the support tube 2 and hydrogen as fuel to the surroundings. Then, in the air electrode 4, oxygen reacts with the electrons flowing in the external circuit and is ionized, and the oxygen ions reach the fuel electrode 6 through the solid electrolyte 5. In the fuel electrode 6, the oxygen ions combine with hydrogen to generate electrons and water, and generate electricity by such an electrochemical reaction. In this case, the electricity of the cell 3 is collected by the interconnector 7 and the metal current collectors 8 and 9 in a reducing atmosphere of hydrogen and is taken out. [0008] In the above-mentioned prior art, the fuel electrode 6 is a cermet containing a certain mixture of nickel and zirconia.
In this configuration, the metal current collectors 8 and 9 are simply brought into contact with each other, so that the current collecting resistance is increased, which causes a decrease in the output of the battery. In addition, since the adjacent cells are connected by the metal current collectors 8 and 9 while being in contact with each other, workability is poor, and it is difficult to obtain a uniform contact resistance. As a method for reducing the current collecting resistance between the air electrode 4 and the fuel electrode 6, it is conceivable to form a metal or a mixture of metals on the outer surfaces of the interconnector 7 and the fuel electrode 6, but the production becomes troublesome. There is a problem that the reduction in contact resistance with other cells cannot be eliminated. SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to improve the configuration of a support tube, a fuel electrode, and a current collector to reduce current collection resistance and simplify the structure. It is. In order to achieve the above object, the present invention relates to a cell comprising a fuel cell, a solid electrolyte, and an air electrode formed at least in a cylindrical shape and laminated in a thin film multilayer in a radial direction. In a cylindrical solid electrolyte fuel cell in which current collecting means is provided for each of the fuel electrode and the air electrode , a metal current collecting portion is provided on the inner peripheral portion, and the collector is provided on the outer peripheral side.
High mixing ratio of lamic and metal mixing ratio on inner circumference
It also functions as a current collecting means and support pipe with a tilted structure
The fuel electrode tube is provided at the center . According to the present invention having the above-described structure, the fuel electrode tube having the function of the fuel electrode has a metal current collector on the inner periphery.
Due to the function of tilting the metal in the thickness direction, it becomes thermally matched in a high-temperature atmosphere. When the battery operates, electrons generated in the fuel electrode tube are collected in the axial direction with low resistance. In a high-temperature atmosphere, the fuel electrode tube is joined to the solid electrolyte and the ceramics by the function of tilting the ceramics in the thickness direction, so that a large adhesive strength is obtained, and the solid electrolyte and the air electrode are also thermally matched. . Therefore, these three members are firmly and integrally connected in the entire region in the circumferential and axial directions, and the cells are supported in this connected state, so that a support or the like becomes unnecessary. Embodiments of the present invention will be described below with reference to the drawings. 1 and 2, the overall configuration of a cylindrical vertical stripe solid electrolyte fuel cell will be described. Reference numeral 1 denotes a solid electrolyte fuel cell, which is a relatively thick tubular fuel electrode tube 1.
0, and a single cell 3 is arranged in the fuel electrode tube 10. The fuel electrode tube 10 is formed as a cermet porous film in which nickel, which is a metal having good conductivity, and stabilized zirconia having good thermal compatibility with the solid electrolyte 5 are mixed, and functions as a fuel electrode throughout the axial direction. Have. In this case, for example, in the case of manufacturing by a thermal spraying method, by controlling the compounding ratio of the material, the stabilized zirconia is increased on the outer peripheral side, and the nickel is compounded on the inner peripheral side so as to increase the nickel. A porous current collecting portion 11 made of only nickel is formed at the innermost periphery and is made to be able to serve both as current collecting and supporting. Next, the structure of the cell 3 will be described. A solid electrolyte 5 made of stabilized zirconia is formed on the outer peripheral side of the fuel electrode tube 10 in substantially the entire area in the axial direction, and similarly on the outer peripheral side of the solid electrolyte 5. An air electrode 4 of a porous film of a composite oxide is formed. In this way, the cylindrical fuel electrode tube 10, the solid electrolyte 5, and the air electrode 4 are laminated in a thin-film multilayer in the radial direction without any gap, thereby forming a substantially three-layer integrated film. Then, the arrangement of the fuel electrode 6 and the air electrode 4 is reversed from that in the conventional case, so that hydrogen is supplied to the inner fuel electrode tube 10 and oxygen in the air is supplied to the outer air electrode 4. On the other hand, since the current is collected to form an external circuit,
A metal current collector ring 12 is attached to one end of the inner fuel electrode tube 10.
Are screwed so as to be in contact with the current collector 11 on the inner periphery.
A current collecting ring 13 is fitted to a part of the air electrode 4,
These current collecting rings 12 and 13 are connected to other cells by a connection 14. Next, the operation of this embodiment will be described. First, when the cell 3 is heated to a high temperature of 1000 ° C. during the operation of the fuel cell 1, the fuel electrode tube 10, the solid electrolyte 5 and the air electrode 4 are heated to a high temperature. Therefore, the fuel electrode tube 10
In this case, the joint portion of the inner periphery of the nickel with the current collector 11 is thermally matched by the function of inclining the nickel in the thickness direction, so that a large adhesive strength is ensured without causing separation or the like even in the high-temperature atmosphere. . The joint between the fuel electrode tube 10 and the solid electrolyte 5 becomes a joint between the stabilized zirconia due to the function of tilting the stabilized zirconia in the thickness direction of the fuel electrode tube 10 and is thermally matched. Further, the solid electrolyte 5 and the air electrode 4
Is naturally joined thermally by joining ceramics. Thus, the fuel electrode tube 10, the solid electrolyte 5
In addition, the air electrode 4 is firmly and integrally bonded in the entire area in the circumferential and axial directions in a high-temperature atmosphere, and the cell 3 is supported in this connected state, so that a support or the like becomes unnecessary. Subsequently, when fuel hydrogen or the like is continuously supplied to the inside of the fuel electrode tube 10 and oxygen in the air is supplied to the surroundings, the fuel electrode tube 10, the solid electrolyte 5 and the air electrode 4 are brought into a state where there is no gap. By laminating the thin film multilayer in the radial direction with, electrochemical reaction occurs in the entire area in the circumferential and axial directions. That is, in the air electrode 4 in the high-temperature atmosphere, oxygen actively reacts with the electrons flowing in the external circuit to be ionized, and the ions pass through the stabilized zirconia solid electrolyte 5 in the high-temperature atmosphere due to its characteristics. Then, in the fuel electrode tube 10, oxygen ions that have passed through the solid electrolyte 5 are actively combined with hydrogen, and a combustion reaction occurs to generate electrons and water, thereby efficiently generating electricity. At this time, the fuel electrode tube 10 generates power in substantially the entire axial direction, and the electrons are generated by the nickel current collector 1 on the inner periphery.
1, the electrons are collected with low resistance, and the electrons are
And the connection 14. In the air electrode 4,
Electrons are favorably introduced by the connection 14 and the current collection ring 13. Although the embodiment of the present invention has been described above, it goes without saying that the present invention can be similarly applied to the case where the material and configuration of the fuel electrode tube are different. As described above , according to the present invention, in a cylindrical solid electrolyte fuel cell, a cylindrical fuel electrode tube having a function of a fuel electrode of a porous membrane in which metal and ceramics are mixed. Since the fuel electrode tube has a metal current collecting portion on the inner periphery, the current collecting resistance particularly in the axial direction on the fuel electrode side can be significantly reduced. Also, fuel electrode
Tubes, are inclined the mixing ratio of the metals and ceramics the thickness direction, the solid electrolyte and thermally at a high temperature atmosphere, which is configured to mechanically strong coupling, the support or the like not
It can be important. As a result, the cell structure is simplified.
Can be Therefore, cylindrical solid electrolyte fuel cells
Production time can be shortened, thus reducing costs
Can be achieved. Since the fuel electrode tube is made of a metal and ceramic material, the cost can be reduced. Furthermore, since the cylindrical fuel electrode tube, the solid electrolyte, and the air electrode are formed as a cylindrical vertical stripe in a radially stacked state with no gaps, the power generation efficiency is improved . Furthermore, since the adjacent cells are connected by the current collecting ring and the connection, the present invention is excellent in terms of workability and reduction in resistance when modularized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an embodiment of a cylindrical solid oxide fuel cell according to the present invention. FIG. 2 is an overall perspective view of the embodiment. FIG. 3 is a cross-sectional view showing a conventional cylindrical vertical stripe solid electrolyte fuel cell. [Description of Signs] 1 ... Cylindrical solid electrolyte fuel cell, 3 ... Cell, 4 ... Air electrode, 5 ... Solid electrolyte, 10 ... Fuel electrode tube, 1
1 ... current collector.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoru Yamaoka 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. (72) Mikiyuki Ono 1-1-1, Kiba, Koto-ku, Tokyo Co., Ltd. In Fujikura (56) References JP-A-3-95859 (JP, A) JP-A-5-13090 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 8/02 H01M 8/12

Claims (1)

(57) Claims 1. A fuel electrode formed at least in a cylindrical shape,
A cell is formed by laminating a solid electrolyte and an air electrode in a thin film multilayer in the radial direction, and in a cylindrical solid electrolyte fuel cell in which a current collecting means is provided for each of the fuel electrode and the air electrode , a metal material is formed on an inner peripheral portion. With a current collector, and a ceramic
Increasing the mixing ratio and increasing the metal mixing ratio on the inner circumference side
Fuel electrode tube that has the function of the current collector and support tube of the oblique structure
A cylindrical solid electrolyte fuel cell characterized in that is provided at the center .