JP4146738B2 - Fuel cell, cell stack and fuel cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell, a cell stack, and a fuel cell, and relates to a fuel cell, a cell stack, and a fuel cell that have a good current collecting effect.
[0002]
[Prior art]
In recent years, various types of fuel cells in which a cell stack composed of a plurality of fuel cells is accommodated in a storage container have been proposed as next-generation energy.
[0003]
FIG. 5 shows a cell stack of a conventional solid oxide fuel cell. This cell stack aggregates a plurality of fuel cells 1 (1a, 1b), and one fuel cell 1a and the other fuel cell. A current collecting member 5 made of metal felt is interposed between the cell 1b and the fuel side electrode 7 of one fuel cell 1a and the oxygen side electrode 11 of the other fuel cell 1b are electrically connected. It had been.
[0004]
The fuel cell 1 (1a, 1b) is configured by sequentially providing a solid electrolyte 9 and an oxygen side electrode 11 made of conductive ceramics on the outer peripheral surface of a fuel side electrode 7 whose main component is a cylindrical metal. The fuel-side electrode 7 exposed from the solid electrolyte 9 and the oxygen-side electrode 11 is provided with an interconnector 13 so as not to be connected to the oxygen-side electrode 11 and is electrically connected to the fuel-side electrode 7.
[0005]
The interconnector 13 reliably blocks the fuel gas flowing inside the fuel side electrode 7 and the oxygen-containing gas flowing outside the oxygen-side electrode 11 and is not densely changed by the fuel gas and the oxygen-containing gas. New conductive ceramics are used.
[0006]
The electrical connection between one fuel cell 1a and the other fuel cell 1b is made by connecting the fuel side electrode 7 of one fuel cell 1a to the interconnector 13 provided on the fuel side electrode 7 and the current collecting member 5. It is performed by connecting to the oxygen side electrode 11 of the other fuel battery cell 1b via.
[0007]
The fuel cell is configured by accommodating the cell stack in a storage container. Fuel (hydrogen) is caused to flow inside the fuel side electrode 7 and air (oxygen) is allowed to flow to the oxygen side electrode 11 to generate power at 600 to 1000 ° C. The
[0008]
In recent years, in order to make the thermal expansion coefficients of the solid electrolyte and the fuel side electrode closer, the fuel side electrode is made of Ni and ZrO. ₂ Mullite (3Al ₂ O ₃ ・ 2SiO ₂ ) And spinel (MgAl ₂ O ₄ , CaAl ₂ O ₄ ) Is formed (see Patent Document 1).
[0009]
In such a fuel cell, since the thermal expansion coefficient of the fuel side electrode can be brought close to the thermal expansion coefficient of the solid electrolyte, cracking of the solid electrolyte and separation of the solid electrolyte from the fuel side electrode can be suppressed.
[0010]
[Patent Document 1]
JP-A-7-029574
[0011]
[Problems to be solved by the invention]
However, since the fuel cell 1 described above is provided with the interconnector 13 made of conductive ceramics on the fuel-side electrode 7 whose main component is metal, and this interconnector 13 is connected to the current collecting member 5 made of metal, There was a problem that the electron conductivity from the current collecting member 5 to the fuel side electrode 7 was low, and the power generation efficiency was low.
[0012]
The reason for this is not clear, but may be due to the following reasons. That is, generally, an oxygen side electrode made of a cylindrical conductive ceramic is supported, a fuel electrolyte electrode made of solid electrolyte and metal is formed on the outer surface of the support tube, and an interconnector made of ceramic is connected to the oxygen side electrode. When electrically connecting to the fuel side electrode of another fuel battery cell via a current collecting member made of metal, as shown in FIG. 6 (a), the oxygen side electrode of one fuel battery cell is used. Since a current flows through the fuel side electrode of the other fuel cell, no potential barrier is created between the interconnector and the current collecting member, and the current from the oxygen side electrode of one fuel cell passes through the current collecting member. Can be efficiently transmitted to the other fuel cell.
[0013]
However, as shown in FIG. 5, when the fuel side electrode 7 is used as a support pipe and the solid electrolyte 9 and the oxygen side electrode 11 are formed on the outer surface of the support pipe, the interconnector 13 is provided on the fuel side electrode 7. Since the current collecting member 5 is connected to the interconnector 13, the current flows from the oxygen side electrode of the other fuel battery cell to the fuel of one fuel battery cell as shown in FIG. 6 (b). Since it flows to the side electrode, a potential barrier is created between the current collecting member and the interconnector, rectification occurs, contact becomes non-ohmic, and current from the oxygen side electrode of the other fuel cell is passed through the current collecting member. Therefore, there is a problem in that it cannot be sufficiently transmitted to the fuel-side electrode of one of the fuel cells. Expression attention ...
An object of the present invention is to provide a fuel cell, a cell stack, and a fuel cell that can improve the current collection effect.
[0014]
[Means for Solving the Problems]
The fuel battery cell of the present invention is provided with an oxygen side electrode made of conductive ceramics on one side of a solid electrolyte, a fuel side electrode containing a metal or metal oxide on the other side, and the fuel side electrode made of conductive ceramics. An interconnector is provided, and a P-type semiconductor connected to a current collecting member for electrical connection between cells is provided in the interconnector.
[0015]
In such a fuel cell, the reason is not clear, but the current from the oxygen side electrode of the other fuel cell is supplied to the fuel side of one fuel cell via a current collecting member, a P-type semiconductor, and an interconnector. It can be efficiently transmitted to the electrode. That is, in the present invention, an interconnector and a P-type semiconductor are sequentially provided on the fuel side electrode, and can be connected to a current collecting member for electrical connection with the oxygen side electrode of the other cell. When current flows through the semiconductor, there is a potential barrier, but the contact is ohmic, there is no rectifying effect, and the P-type semiconductor of one fuel cell and the interconnector are connected from the oxygen side electrode of the other fuel cell. Thus, the current flow to the fuel side electrode can be promoted, and the current collecting effect can be improved. Thereby, a fuel cell excellent in power generation performance can be provided.
[0016]
In the fuel battery cell of the present invention, it is desirable that one or more fuel gas passages are provided inside the fuel side electrode, and a solid electrolyte and an oxygen side electrode are sequentially provided on the outer surface of the fuel side electrode. . As such a fuel battery cell, for example, the fuel side electrode is plate-like, and a solid electrolyte and an oxygen side electrode are sequentially provided on one side main surface of the fuel side electrode, and on the other side main surface, Some interconnectors and P-type semiconductors are sequentially provided. In such a fuel cell, as described above, although the reason is not clear, the current from the oxygen side electrode of the other fuel cell is provided on the current collector and the other main surface of the fuel side electrode. It can be efficiently transmitted to the fuel side electrode via the P-type semiconductor and the interconnector.
[0017]
The P-type semiconductor is characterized in that it is formed in a planar shape on the surface of the interconnector so as to face the oxygen-side electrode through the fuel-side electrode. In such a fuel cell, the current flowing from the oxygen side electrode of the other fuel cell to the P-type semiconductor flows to the fuel side electrode at the shortest distance, and the P-type semiconductor and the oxygen side electrode are opposed to each other. In addition, a cell stack in which a plurality of power generation units sandwiching a solid electrolyte between a fuel side electrode and an oxygen side electrode can be connected at the shortest distance, and current loss can be minimized.
[0018]
In the fuel cell of the present invention, the P-type semiconductor is preferably made of the same component as the oxygen side electrode. Thereby, while reducing the kind of material which comprises a fuel battery cell, for example, after forming the solid electrolyte outside the fuel side electrode, and forming the laminated body which provided the interconnector in the fuel side electrode by integral firing, Formation of the oxygen side electrode on the surface of the solid electrolyte and formation of the P-type semiconductor on the surface of the interconnector can be performed simultaneously.
[0019]
Furthermore, in the fuel cell of the present invention, the thickness of the P-type semiconductor is 10 μm or more. By setting the thickness of the P-type semiconductor to 10 μm or more, for example, even when a part of the current collecting member comes into contact with the P-type semiconductor, the current from the current collecting member is directed in multiple directions from the contact part with the P-type semiconductor. For example, in the case of the plate-like fuel side electrode described above, current flows through the fuel side electrode in the thickness direction at the shortest distance, and current loss can be suppressed to a minimum.
[0020]
The cell stack of the present invention comprises a plurality of the above-described fuel cells, and a current collecting member containing metal interposed between one fuel cell and the other fuel cell, and the one fuel The fuel-side electrode of the battery cell may be electrically connected to the oxygen-side electrode of the other fuel battery cell via an interconnector provided on the fuel-side electrode, a P-type semiconductor, and the current collecting member. desirable.
[0021]
In the cell stack of the present invention, the fuel side electrode of one fuel battery cell is electrically connected to the oxygen side electrode of the other fuel battery cell via an interconnector, a P-type semiconductor, and a current collecting member provided on the fuel side electrode. Therefore, the electric current is connected from the oxygen side electrode made of ceramic of the other fuel cell to the P-type semiconductor of one fuel cell and the interconnector made of conductive ceramic through the current collecting member made of metal. It can flow efficiently to the fuel-side electrode containing metal as a main component, improve the electron conductivity between the cells, and improve the power generation efficiency of the fuel cell.
[0022]
The fuel cell of the present invention is obtained by housing the cell stack in a storage container. In such a fuel cell, since the electron conductivity between cells can be improved as described above, the power generation characteristics of the fuel cell can be improved.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Form 1
FIG. 1 shows a cross section of a fuel cell according to the present invention. The fuel cell has a cylindrical shape. In this fuel cell, a dense solid electrolyte 33 and an oxygen-side electrode 35 made of porous conductive ceramics are sequentially laminated on the outer surface of a fuel-side electrode 31 mainly composed of a cylindrical porous metal, An interconnector 37 and a P-type semiconductor 39 are sequentially formed on the outer surface of the fuel side electrode 31, and the fuel side electrode 31 serves as a support.
[0024]
The fuel-side electrode 31 is mainly composed of any one of Ni, Co, Ti, and Ru, or a metal oxide, or an alloy or alloy oxide thereof. In order to improve the bonding strength to 33 and approximate the thermal expansion coefficient of the solid electrolyte 33, it is desirable to contain a solid electrolyte material. As the metal or metal oxide, Ni or NiO is desirable from the viewpoint of cost.
[0025]
Inside the fuel side electrode 31, one fuel gas passage 31 a formed concentrically in the axial direction of the fuel side electrode 31 is formed. The outer diameter of the cylindrical fuel-side electrode 31 is preferably 3 to 30 mm from the viewpoint of improving the power density per volume, and the wall thickness is preferably 0.5 to 5 mm from the viewpoint of improving the cell strength. The fuel side electrode 31 does not need to be cylindrical, and may be an elliptical cylinder or a square cylinder.
[0026]
The solid electrolyte 33 provided on the outer surface of the fuel side electrode 31 is partially stabilized or stabilized ZrO containing 3 to 15 mol% Y and rare earth elements. ₂ Dense ceramics are used. In order to improve the bonding strength between the fuel side electrode 31 and the solid electrolyte 33, a bonding layer made of a dense layer may be interposed. The thickness of the solid electrolyte 33 is preferably 10 to 100 μm from the viewpoint of preventing gas permeation.
[0027]
The oxygen side electrode 35 is made of LaMnO. ₃ Material, LaFeO ₃ Material, LaCoO ₃ It is comprised from the at least 1 type of porous electroconductive ceramics of a system material. The oxygen-side electrode 35 is LaFeO because it has high electrical conductivity at a relatively low temperature of about 600 to 1000 ° C. ₃ System materials are desirable. The thickness of the oxygen-side electrode 35 is preferably 30 to 100 μm from the viewpoint of current collection.
[0028]
A part of the outer surface of the fuel side electrode 31 has a portion in which the solid electrolyte 33 and the oxygen side electrode 35 are not formed in the axial length direction, and is exposed from the solid electrolyte 33 and the oxygen side electrode 35. An interconnector 37 made of conductive ceramics is formed on the outer surface of the fuel side electrode 31.
[0029]
The thickness of the interconnector 37 is preferably 30 to 200 μm from the viewpoint of denseness and electrical resistance. The interconnector 37 is LaCrO ₃ It is composed of a conductive ceramic material. The interconnector 37 is made dense to prevent leakage of fuel gas and oxygen-containing gas inside and outside the fuel-side electrode 31, and the inner and outer surfaces of the interconnector 37 are in contact with the fuel gas and oxygen-containing gas. Therefore, it has reduction resistance and oxidation resistance.
[0030]
A bonding layer may be interposed between the end face of the interconnector 37 and the end face of the solid electrolyte 33 in order to improve the sealing performance.
[0031]
In the fuel cell of the present invention, a porous P-type semiconductor 39 is provided on the entire outer surface of the interconnector 37. The P-type semiconductor 39 is not a general impurity semiconductor, but LaCrO constituting the interconnector 37 in order to operate in a use environment. ₃ The same component as that of the oxygen side electrode 35 which is a P-type semiconductor made of ceramic having a higher electronic conductivity than the base material, that is, LaMnO ₃ Material, LaFeO ₃ Material, LaCoO ₃ It is desirable to consist of at least one type of system material. In particular, the same component as that of the oxygen-side electrode 35 is desirable, and further, the same composition is desirable.
[0032]
The thickness of the P-type semiconductor 39 is preferably 10 μm or more, particularly 50 μm or more from the viewpoint of current collection, and is 100 μm or less from the viewpoint of reducing the difference in thermal expansion from other members (solid electrolyte, etc.). It is desirable. Furthermore, it is desirable to be porous from the viewpoint of reducing the difference in thermal expansion with other members.
[0033]
A method for manufacturing the fuel cell as described above will be described. First, for example, NiO powder and ZrO containing Y ₂ A fuel-side electrode material in which (YSZ) powder, an organic binder, and a solvent are mixed is extruded to produce a cylindrical fuel-side electrode molded body, which is dried.
[0034]
Next, for example, a sheet-like molded body is prepared using a solid electrolyte material in which YSZ powder, an organic binder, and a solvent are mixed, and this sheet-shaped molded body is formed on the fuel-side electrode molded body at both ends thereof. It winds so that a space | interval may space apart, and it dries.
[0035]
After this, for example, LaCrO ₃ A sheet-like molded body is prepared using an interconnector material in which a system material, an organic binder, and a solvent are mixed, and this sheet-shaped molded body is laminated on the exposed outer surface of the fuel-side electrode molded body to form a cylindrical shape. A laminated molded body in which a solid electrolyte sheet-shaped molded body and an interconnector sheet-shaped molded body are laminated on the fuel-side electrode molded body is prepared.
[0036]
Next, the laminated molded body is treated to remove the binder, and co-fired at 1300 to 1600 ° C. in an oxygen-containing atmosphere. ₃ It is immersed in a paste containing a system material and a solvent, and an oxygen-side electrode molded body is formed on the surface of the solid electrolyte by dipping, and LaFeO ₃ The above-mentioned paste containing the system material is applied to the outer surface of the interconnector and baked at 1000 to 1300 ° C., thereby forming the porous oxygen side electrode 35 and the P-type semiconductor 39 at the same time. Can be made.
[0037]
As shown in FIG. 2, the cell stack of the present invention includes a plurality of fuel battery cells 40 (40a, 40b), and between one fuel battery cell 40a and the other fuel battery cell 40b, A current collecting member 41 made of metal felt and / or a metal plate is interposed, and the fuel side electrode 31 of one fuel cell 40a is connected to an interconnector 37, a P-type semiconductor 39, a current collector provided on the fuel side electrode 31. It is configured to be electrically connected to the oxygen side electrode 35 of the other fuel battery cell 40b via the member 41. The current collecting member 41 is preferably made of at least one of Pt, Ag, Ni-base alloy, and Fe—Cr steel alloy from the viewpoint of heat resistance, oxidation resistance, and electrical conductivity.
[0038]
In the fuel cell of the present invention, the cell stack of FIG. 2 is accommodated in a storage container to constitute a fuel cell. During power generation, as indicated by an arrow in FIG. 2, the current from the oxygen-side electrode 35 of the other fuel cell 40b is supplied to the current collecting member 41, the P-type semiconductor 39 of the one fuel cell 40a, and the interconnector 37. Is transmitted to the fuel-side electrode 31 via.
[0039]
Therefore, the current flows as shown in FIG. 6B. However, since the P-type semiconductor 39 is provided between the current collecting member 41 and the interconnector 37, the current can flow efficiently.
[0040]
Form 2
FIG. 3 shows another embodiment of the fuel battery cell of the present invention. The fuel battery cell of FIG. 3 has a flat cross section and a flat plate shape as a whole, and a plurality of fuel gases are contained therein. A passage 51 is formed.
[0041]
This fuel battery cell has a flat cross section and an oxygen side electrode 57 made of a dense solid electrolyte 55 and porous conductive ceramics on the outer surface of a porous fuel side electrode 53 that is plate-like as a whole. Are sequentially stacked, and an interconnector 59 is formed on the outer surface of the fuel side electrode 53 opposite to the oxygen side electrode 57. A plurality of fuel gas passages 51 are formed in the fuel side electrode 53.
[0042]
That is, the fuel cell has a cross-sectional shape including arc-shaped portions m provided at both ends in the width direction and a pair of flat portions n connecting these arc-shaped portions m, and the pair of flat portions n is flat. And are formed substantially in parallel. One of the pair of flat portions n is configured by forming an interconnector 59 on one main surface of the plate-like fuel-side electricity 53, and the other flat portion n is formed of the plate-like fuel-side electrode 53. A solid electrolyte 55 and an oxygen side electrode 57 are formed on the other main surface.
[0043]
The distance between the arc-shaped portions mm of the fuel battery cell 33 is preferably in the range of 10 mm to 80 mm, and more preferably in the range of 15 mm to 40 mm, from the viewpoint that the fuel battery cell can be downsized to obtain a desired power generation amount. . The distance between the flat portions nn is preferably in the range of 2 mm to 10 mm, and more preferably in the range of 3 mm to 5 mm, from the viewpoint of reducing the potential drop (current loss) in the fuel side electrode 53. .
[0044]
The P-type semiconductor 61 is formed in a planar shape on the surface of the interconnector 59 so as to face the oxygen-side electrode 57 through the fuel-side electrode 53. That is, the solid electrolyte 55 and the oxygen side electrode 57 are provided on one main surface of the plate-like fuel side electrode 53, and the interconnector 59 and the P-type semiconductor 61 are connected to the other side of the plate-like fuel side electrode 53. As shown by the arrow in FIG. 3, the plate-like fuel side electrode 53 is provided in a plane shape on the main surface and the current flowing from the oxygen side electrode of the other fuel cell to the P-type semiconductor 61. Since the P-type semiconductor 61 and the oxygen-side electrode 57 are opposed to each other in the thickness direction, and the P-type semiconductor 61 and the oxygen-side electrode 57 are opposed to each other, the power generation units sandwiching the solid electrolyte 55 between the fuel-side electrode 53 and the oxygen-side electrode 57 are connected to each other. And current loss in the cell stack can be minimized. The solid electrolyte 55 is formed up to the arc-shaped portion m and joined to the end portion of the interconnector 59 formed only on the other main surface of the fuel side electrode 53.
[0045]
The thickness of the P-type semiconductor 61 is 10 μm or more. Thereby, for example, even when the current collecting member 63 makes point contact with the P-type semiconductor 61 (including the case where the current collecting member 63 is linearly contacted), a large amount of current from the current collecting member 63 is generated from the contact portion with the P-type semiconductor 61. Dispersed in the direction, current flows between the plate-like fuel side electrodes 53 at the shortest distance in the thickness direction, and current loss at the fuel side electrode 53 can be minimized. It is desirable that the thickness be 50 μm or more from the viewpoint that current is distributed in multiple directions from the contact portion with the P-type semiconductor 61. On the other hand, the thickness of the P-type semiconductor 61 is preferably 100 μm or less and more preferably porous from the viewpoint of suppressing peeling due to a difference in thermal expansion with other members.
[0046]
Such a fuel battery cell is first composed of, for example, Ni and / or NiO powder and a rare earth element such as ZrO containing Y. ₂ (YSZ), an organic binder, and a solvent are mixed and extruded to produce a flat fuel-side electrode molded body, which is dried and degreased.
[0047]
Next, ZrO in which rare earth elements are dissolved ₂ Using a solid electrolyte material in which powder, an organic binder, and a solvent are mixed, a sheet-shaped solid electrolyte molded body is produced, and the sheet-shaped solid electrolyte molded body is formed on one main surface of the fuel-side electrode molded body. Laminated and wound so that both ends are spaced apart by a predetermined distance, and dried.
[0048]
Next, a sheet-like interconnector molded body is produced using an interconnector material in which a lanthanum-chromium oxide powder, an organic binder, and a solvent are mixed, and the interconnector molded body is formed at both ends of the solid electrolyte molded body. Is laminated on the fuel side electrode molded body exposed from the portion.
[0049]
Thereby, while laminating | stacking a solid electrolyte molded object on the one side main surface of a flat fuel side electrode molded object, the laminated molded object by which the interconnector molded object was laminated | stacked on the surface of the other flat part is produced. Each molded body can be produced by sheet molding using a doctor blade, printing, slurry dip, spraying by spraying, or the like, or a combination thereof.
[0050]
Next, the multilayer molded body is degreased and cofired at 1300 to 1600 ° C. in an oxygen-containing atmosphere.
[0051]
Next, a transition metal perovskite oxide powder that is a P-type semiconductor, for example, LaFeO ₃ A system powder and a solvent are mixed to prepare a paste, and the laminate is dipped in the paste or directly sprayed and baked at 1000 to 1300 ° C., so that the surface of the solid electrolyte 55 and the interconnector 61 is obtained. Each of the porous oxygen side electrode 57 and the P-type semiconductor 61 is simultaneously formed to produce the fuel cell of the present invention.
[0052]
The oxygen side electrode 57 and the P-type semiconductor 61 may be made of different materials. However, the oxygen-side electrode 57 and the P-type semiconductor 61 are made of the same component, in particular, the same composition from the viewpoint of easy production. It is desirable to configure.
[0053]
In such a cell stack of flat fuel cells, a current collecting member 63 made of a metal felt and / or a metal plate is interposed between one fuel cell and the other fuel cell, and one fuel cell is interposed. The fuel-side electrode 53 of the battery cell is electrically connected to the oxygen-side electrode of the other fuel cell via an interconnector 59, a P-type semiconductor 61, and a current collecting member 63 provided on the fuel-side electrode 53. Composed.
[0054]
The current collecting member 63 is preferably made of at least one of Pt, Ag, Ni-base alloy, and Fe—Cr steel alloy from the viewpoint of heat resistance, oxidation resistance, and electrical conductivity.
[0055]
The fuel cell of the present invention is configured by storing a cell stack including a plurality of the fuel cells shown in FIG. 3 in a storage container. The storage container is provided with an introduction pipe for introducing a fuel gas such as hydrogen and an oxygen-containing gas such as air into the fuel cell from outside, and generates electricity when the fuel cell is heated to a predetermined temperature. Excess fuel gas and oxygen-containing gas are burned and discharged out of the storage container as combustion gas.
[0056]
In addition, this invention is not limited to the said form, A various change is possible in the range which does not change the summary of invention.
[0057]
【Example】
First, NiO powder having an average particle diameter of 0.5 μm and ZrO containing 8 mol% of Y having an average particle diameter of 0.5 μm. ₂ (YSZ) The fuel side electrode material which mixed the powder, the organic binder which consists of a pore agent and PVA, and the solvent which consists of water was extrusion-molded, the cylindrical fuel side electrode molded object was produced, and this was dried. .
[0058]
Next, the YSZ powder, an organic binder made of an acrylic resin, and a solvent made of toluene are mixed to produce a sheet-like molded body, and the sheet-shaped molded body is formed into a fuel-side electrode. It was wound on the body so that the both ends thereof were separated from each other with a predetermined interval, and dried.
[0059]
After this, LaCrO having an average particle diameter of 2 μm ₃ A sheet-like molded body is prepared using an interconnector material in which a system material, an organic binder made of an acrylic resin, and a solvent made of toluene are mixed, and this sheet-like molded body is made of an exposed fuel-side electrode molded body. A laminated molded body was prepared by laminating on the outer surface and laminating a sheet-shaped molded body of solid electrolyte and a sheet-shaped molded body of interconnector on a cylindrical fuel-side electrode molded body.
[0060]
Next, the laminated molded body was debindered and co-fired at 1500 ° C. in the air. This laminate is made of La having an average particle diameter of 2 μm. _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ Immerse in a paste containing a powder and a normal paraffin solvent and dip an oxygen-side electrode molded body on the surface of the solid electrolyte. Apply the paste to the outer surface of the interconnector and bake at 1150 ° C. A porous oxygen-side electrode was formed, and a porous P-type semiconductor was formed on the outer surface of the interconnector to produce a fuel cell of the present invention as shown in FIG.
[0061]
A Pt paste is applied to the oxygen side electrode and the P-type semiconductor of the fuel cell, and a Pt mesh (current collecting member) is pressed against the P-type semiconductor to pass a current having a predetermined current density between the oxygen side electrode and the P-type semiconductor. The voltage drop between the fuel side electrode and the P-type semiconductor was measured and shown in FIG. 4 with a solid line.
[0062]
The outer diameter of the fuel side electrode was 15 mm, the inner diameter was 12 mm, the thickness of the solid electrolyte was 40 μm, the thickness of the oxygen side electrode was 50 μm, the thickness of the interconnector was 50 μm, and the thickness of the P-type semiconductor was 50 μm.
[0063]
Further, a fuel cell of a comparative example was produced in the same manner as described above except that no P-type semiconductor was formed, a Pt mesh (current collecting member) was pressed against the interconnector, and the voltage drop was measured in the same manner as described above. Is indicated by a broken line.
[0064]
From FIG. 4, the fuel cell of the present invention in which a P-type semiconductor is formed on the outer surface of the interconnector has a smaller voltage drop than the fuel cell of the comparative example, can increase the current collection characteristics, and can obtain a high output. I understand.
[0065]
Example 2
A flat fuel cell as shown in FIG. 3 was produced using the same material and production method as in Example 1. At this time, the distance (width) between m and m of the fuel cell is 26 mm, the distance (thickness) between nn is 3.5 mm, the length is 200 mm, the thickness of the dense solid electrolyte 55 is 30 μm, porous The thickness of the fine oxygen side electrode 57 was 50 μm, the thickness of the dense interconnector 59 was 50 μm, and the thickness of the porous P-type semiconductor 61 was 50 μm. In addition, as a comparative example, a fuel cell that does not form a P-type semiconductor was also produced.
[0066]
When the voltage drop of these fuel cells was determined in the same manner as in Example 1, the current density was 1.25 A / cm. ² At that time, the voltage drop was 0.6 V in the fuel cell of the present invention, whereas it was as large as 1.4 V in the fuel cell of the comparative example. Moreover, in the fuel battery cell of the present invention, the P-type semiconductor was not peeled off due to the difference in thermal expansion.
[0067]
Further, the present inventors produced a fuel cell as shown in FIG. 3 in the same manner as described above except that the thickness of the P-type semiconductor 61 was changed to 10 μm, 70 μm, and 100 μm, and evaluated the voltage drop. .
[0068]
As a result, the current density was 1.25 A / cm. ² When the thickness of the P-type semiconductor 61 was 10 μm, 70 μm, and 100 μm, the voltage drops were 0.62 V, 0.59 V, and 0.58 V, respectively. Moreover, in the fuel battery cell of the present invention, the P-type semiconductor was not peeled off due to the difference in thermal expansion.
[0069]
【The invention's effect】
In the fuel battery cell of the present invention, an oxygen-side electrode made of conductive ceramics is provided on one side of the solid electrolyte, a fuel-side electrode containing a metal or metal oxide is provided on the other side, and an interface made of conductive ceramics is provided on the fuel-side electrode. Since a connector is provided and a P-type semiconductor connected to a current collecting member for electrical connection between cells is provided in the interconnector, the current from the oxygen side electrode of the other fuel cell is supplied to the current collecting member. Thus, the fuel cell can be efficiently transmitted to the P-type semiconductor, the interconnector, and the fuel side electrode of one of the fuel cells, and the current collecting performance can be improved, thereby providing a fuel cell having excellent power generation performance.
[Brief description of the drawings]
1A and 1B show a fuel cell of the present invention, in which FIG. 1A is a cross-sectional view and FIG. 1B is a perspective view.
FIG. 2 is a cross-sectional view showing a cell stack of the present invention.
FIG. 3 is a cross-sectional view showing another fuel battery cell of the present invention in which a plurality of fuel gas passages are formed in a fuel side electrode.
FIG. 4 is a graph showing a voltage drop between a P-type semiconductor and a fuel-side electrode.
FIG. 5 is a cross-sectional view showing a conventional cell stack.
6A and 6B show a connection structure between cells and a current flow. FIG. 6A is an explanatory diagram showing a case where an oxygen side electrode is used as a support tube, and FIG. 6B is an explanatory diagram showing a case where a fuel side electrode is used as a support tube. is there.
[Explanation of symbols]
31, 53 ... Fuel side electrode
33, 55 ... Solid electrolyte
35, 57 ... Oxygen side electrode
37, 59 ... interconnector
39, 61... P-type semiconductor
40 (40a, 40b): Fuel cell
41, 63 ... current collecting member

Claims (9)

An oxygen-side electrode made of conductive ceramics is provided on one side of the solid electrolyte, a fuel-side electrode containing a metal or metal oxide is provided on the other side, and an interconnector made of conductive ceramics is provided on the fuel-side electrode. And a P-type semiconductor connected to a current collecting member for electrical connection between the cells. 2. The fuel according to claim 1, wherein one or more fuel gas passages are provided inside the fuel side electrode, and a solid electrolyte and an oxygen side electrode are sequentially provided on the outer surface of the fuel side electrode. Battery cell. The fuel side electrode is plate-shaped, the solid electrolyte and the oxygen side electrode are sequentially provided on one main surface of the fuel side electrode, and the interconnector and the P-type semiconductor are sequentially provided on the other main surface. The fuel cell according to claim 1 or 2, wherein 4. The fuel cell according to claim 3, wherein the P-type semiconductor is formed in a planar shape on the surface of the interconnector so as to face the oxygen side electrode through the fuel side electrode. 5. The fuel cell according to claim 1, wherein the P-type semiconductor is made of the same component as the oxygen-side electrode. 6. The fuel cell according to claim 1, wherein the P-type semiconductor is formed simultaneously with the oxygen side electrode. The fuel cell according to claim 1, wherein the P-type semiconductor has a thickness of 10 μm or more. A plurality of fuel cells according to any one of claims 1 to 7 are assembled, and a current collecting member containing metal is interposed between one fuel cell and the other fuel cell, The fuel side electrode of one fuel cell is electrically connected to the oxygen side electrode of the other fuel cell via an interconnector provided on the fuel side electrode, a P-type semiconductor, and the current collecting member. A cell stack characterized by 9. A fuel cell comprising the cell stack according to claim 8 housed in a housing container.

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