JPH11283657A - Flat solid-electrolyte fuel cell and cell-stack using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the strength of a cell-stack, to reduce the cost of machining by making it easier to machine parts, to enhance output characteristic, and to reduce the cost of materials. SOLUTION: A cell 1 has a fuel electrode (porous fuel electrode) 2 made of a porous material, an electrolyte film 3 formed on either the front or back surface of the porous fuel electrode 2, an air electrode film 4 formed over the electrolyte film 3, a separator film 5 formed on the other surface of the porous fuel electrode 2, and a porous air electrode 6 joined with the air electrode film 4. The cells 1 are stacked and a manifold plate 11 is mounted on the side faces thereof to form a cell-stack 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat cell type solid electrolyte fuel cell and a cell stack using the same. More specifically, the present invention relates to an improvement in the structure of a single cell.

[0002]

2. Description of the Related Art A solid electrolyte fuel cell has an air electrode supplied with air containing oxygen from the outside, a fuel electrode supplied with a fuel gas such as hydrogen or carbon monoxide or methane from the outside,
An electrolyte through which oxygen ions can pass is provided between these two electrodes, and power is generated by an electrochemical reaction between fuel gas and oxide ions. The air electrode receives electrons from the outside and reacts with oxygen in the air to generate oxygen ions. Then, when the oxygen ions pass through the electrolyte and reach the fuel electrode, the oxygen ions react with the fuel gas at the fuel electrode to release products and send out electrons to an external circuit.

[0003] As one type of the solid electrolyte fuel cell, there is a flat type. In a flat plate type solid electrolyte fuel cell, a single cell is formed by forming a fuel electrode film on one surface of the electrolyte plate, for example, the front surface side, and forming an air electrode film on the other surface, the back surface side. The cell stack is formed by stacking single cells with a separator plate having a gas flow path formed therebetween, and attaching a metal manifold plate for distributing gas for each electrode to the periphery.

[0004]

However, in the above-mentioned flat solid electrolyte fuel cell, the strength of the cell stack is maintained by the electrolyte plate and the separator plate. In order to prevent the cell stack from being damaged, very high precision is required for the dimensions and flatness of the electrolyte plate and the separator plate. For this reason, the processing cost increases and quality control must be strict.

[0005] Further, since the separator plate and the single cell are stacked as separate members, the electrical resistance between them becomes large, and the electric output of the cell stack is lost.

In addition, since the separator plate is provided with ribs and the like to allow gas to flow therethrough to form a flow path between each electrode, the separator plate is apt to be damaged due to lack of strength, and the processing cost is increased.

Further, since the material used for the separator plate is relatively expensive, the material cost of the cell stack increases.

Further, since the manifold plate provided around the stacked body in which the single cells are stacked is made of metal, the coefficient of thermal expansion is greatly different from that of the single cell stacked body. For this reason, thermal stress is generated between the stacked body and the manifold plate at the time of power generation, which causes damage to the cell stack.

Accordingly, the present invention provides a flat solid electrolyte fuel cell which improves the strength of a cell stack, facilitates component processing, reduces processing costs, improves output characteristics, and further reduces material costs. The purpose is to provide.

[0010]

In order to achieve the above object, a single cell of the flat solid electrolyte fuel cell according to the first aspect of the present invention comprises a fuel cell made of a porous material, and either a front surface or a back surface of the fuel electrode. An electrolyte film formed on one surface, an air electrode film formed on the electrolyte film, a separator film formed on the other surface of the fuel electrode, and air formed of a porous material bonded to the air electrode film Poles. Claim 2
The single cell of the flat plate type solid electrolyte fuel cell described above, an air electrode made of a porous body, an electrolyte film formed on one of the front surface and the back surface of the air electrode, and formed on the electrolyte film A fuel electrode membrane, a separator film formed on the other surface of the air electrode, and a fuel electrode made of a porous material bonded to the fuel electrode film are provided.

Therefore, since the fuel electrode and the air electrode are formed of the porous material, the gas can flow through the inside of each electrode member and contact the electrode members to cause a reaction. For this reason, there is no need to provide ribs or the like for forming the gas flow path, so that the structure of the single cell can be simplified and the strength can be improved.

Further, since a porous body is used for the fuel electrode and the air electrode, it can be made softer than a solid solid made of the material of each electrode member. For this reason, since the thermal stress at the time of the power generation operation of the cell stack in which the single cells are stacked can be absorbed and reduced, the flexibility of the cell stack can be improved and the strength can be improved. Further, since high processing accuracy of a single cell for preventing damage due to thermal stress is not required, manufacturing cost can be reduced.

Furthermore, since the gas is circulated inside the porous body, the contact area with the gas per unit volume of the electrode member can be increased. For this reason, the power generation performance in a single cell can be improved.

Further, since the separator is directly formed on the fuel electrode or the air electrode made of a porous material, the separator film enters into a large number of minute holes of the fuel electrode or the air electrode, and the separator film enters between them. The contact area can be increased. For this reason, the contact resistance between the fuel electrode or the air electrode and the separator (electric resistance of the contact portion) can be significantly reduced, so that the power generation performance can be improved.

In addition, since both the separator and the electrolyte are membranes, power loss due to their internal resistance can be reduced. Thereby, power generation performance can be improved. Further, since the separator is formed of a membrane, the amount of expensive separator material used can be reduced. Therefore, the manufacturing cost of the single cell can be reduced.

According to a third aspect of the present invention, there is provided a cell stack for a flat solid electrolyte fuel cell, wherein the single cells according to the first or second aspect are stacked in series, and a conductive property is provided between adjacent single cells in the stacking direction. Is provided with a laminate in which the bonding material is interposed.

Therefore, the contact area between the porous body of the single cell adjacent in the laminating direction and the separator film can be increased, and the contact resistance between them can be reduced. Thereby, the power generation performance by the cell stack can be improved.

Further, in the cell stack of the flat solid electrolyte fuel cell according to the fourth aspect, a ceramic manifold plate is provided for the stacked body. Therefore, since the manifold plate can be easily cut, a gas flow hole can be formed in the manifold plate after assembling the laminate and providing the manifold plate around the laminate. Here, this perforation work can be performed by attaching the manifold plate to the laminate, and then checking the position where the circulation hole is to be formed by observing the side surface of the laminate where the manifold plate is not attached. It is not necessary to form a hole, and the accuracy of the position of the through hole can be easily improved. For this reason, it is not necessary to previously form the flow holes in the manifold plate before mounting based on the actually measured values of the laminate as in the related art, so that high processing accuracy can be eliminated.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on an example of an embodiment shown in the drawings. As shown in FIGS. 1 and 5, a single cell 1 of the flat solid electrolyte fuel cell according to the present embodiment includes a fuel electrode (hereinafter, referred to as a porous fuel electrode) 2 made of a porous material, and a porous fuel electrode. An electrolyte membrane 3 formed on one of the front surface and the back surface of 2;
An air electrode membrane 4 formed on the electrolyte membrane 3 and a porous fuel electrode 2
And a cathode (hereinafter, referred to as a porous cathode) 6 made of a porous material and bonded to the cathode membrane 4.

The porous fuel electrode 2 is made of a porous plate material obtained by mixing nickel (nickel oxide at the time of production) and zirconia (YSZ) stabilized by dissolving yttria in a solid solution and sintering the mixture. This mixed material of nickel and YSZ is generally used as a fuel electrode material for a flat plate solid electrolyte fuel cell (SOFC). The porous plate is formed so that the fuel gas can be sufficiently circulated and the strength required for the single cell 1 and the sufficient conductivity of electrons and oxygen ions are provided. For this reason, since the fuel electrode is formed of the porous body, the contact area with the fuel gas per unit volume of the electrode member can be widened and the power generation performance can be improved.
Further, since the structure of the single cell 1 can be simplified as compared with the complicated structure of the conventional single cell in which a gas passage is formed by providing ribs and the like, it is not necessary to increase the assembly accuracy. Therefore, the manufacture of the cell stack 14 can be facilitated, and the strength of the cell stack 14 against thermal stress and external force can be increased. Further, since the strength of the cell stack 14 is increased, the dimensions of the porous fuel electrode 2 and the like can be enlarged, and the power generation performance of the cell stack 14 can be improved.

Here, as the material to be used for the porous fuel electrode 2, it is preferable to use the fuel electrode material according to the invention which has been already filed by the present applicant. This fuel electrode material is a mixture of YSZ coarse particles having a relatively large particle size, YSZ fine particles having a relatively small particle size, and nickel oxide or nickel particles (see Japanese Patent Application No. 7-127375). .
According to this mixture, since the skeleton is formed by the YSZ coarse particles inside the porous fuel electrode 2, the strength of the single cell 1 can be improved, and the porosity change and the volume change under a high temperature and reducing atmosphere. Since the shrinkage can be extremely reduced, it is possible to extend the life of the porous fuel electrode 2 and stabilize the high performance for a long time.

In this embodiment, the porous fuel electrode 2 is made of a mixed material of nickel and YSZ. However, the present invention is not limited to this, and it goes without saying that a known or new material can be used as the fuel electrode material. . Also in this case, since the fuel electrode is formed by the porous fuel electrode 2, the power generation performance can be improved, and the structure of the unit cell 1 is simplified to increase the strength against thermal stress and external force. Can be.

As the electrolyte membrane 3 interposed between the fuel electrode and the air electrode, for example, it is preferable to use a YSZ film that is dense enough to prevent the flow of fuel gas or air. In the present embodiment, the electrolyte membrane 3 is formed not only on one of the front surface and the back surface of the porous fuel electrode 2 but also on a part of the peripheral side surface. The portion covering either the front surface or the back surface of the porous anode 2 functions as an electrolyte, and the electrolyte film 3 covering the side surface functions as a gas seal film. Each is configured. Further, the sealing portion 8 covers the entire edge portion of the pair of side surfaces of the porous fuel electrode 2 facing the electrolyte portion 7 and performs gas sealing of the edge portion 8a.
And a corner film portion 8b for performing gas sealing so as to cover both corners of another pair of opposed side surfaces and leave the gas inflow / outlet opening 18 on the side surface therebetween.

Further, YSZ of the electrolyte membrane 3 enters many small holes of the porous fuel electrode 2 depending on the film formation method. For this reason, compared with the conventional case where a relatively dense fuel electrode is formed on a YSZ flat plate, the contact area of the fuel electrode with the electrolyte is increased to increase the electrode reaction field and increase the oxygen ion path. Can be formed. Therefore, the performance of the flat solid electrolyte fuel cell can be improved. In the present embodiment, the electrolyte membrane 3 is made of a YSZ film. However, the present invention is not limited to this, and a known or new material that can be used as an electrolyte membrane may be used. Also in this case, the contact area between the fuel electrode and the electrolyte can be increased to increase the electrode reaction field.

In this embodiment, since the fuel electrode and the air electrode are made of a porous material, the strength of the unit cell 1 can be secured by the fuel electrode and the air electrode themselves. For this reason, in the conventional single cell 1, the electrolyte and the separator, which had to be a plate material having a certain thickness in order to secure its strength, can be used as a membrane. For example, the thicknesses of the electrolyte membrane 3 and the separator 5 are set to about several tens of μm. Therefore, power loss in the electrolyte membrane 3 and the separator 5 can be prevented, and the power generation performance of the flat solid electrolyte fuel cell can be improved.

The separator membrane 5 is interposed between the single cells 1 and separates the fuel gas and the air so as not to mix. The separator film 5 is formed of a ceramic film such as strontium dopantran chromite-based oxide (lanthanum chromite) that is dense enough not to allow fuel gas or air to flow. In the present embodiment, the separator membrane 5 is composed of a pair of a surface of the porous fuel electrode 2 opposite to the surface on which the electrolyte portion 7 is formed, and a pair of the porous fuel electrode 2 on which the edge film portion 8a is formed. The film is formed so as to cover the entire side surface. For this reason, since the separator film 5 functions as a gas seal film over the entire area where the film is formed, the porous fuel electrode 2 is provided with a gas inflow / outflow opening at the center of a pair of side surfaces where the separator film 5 and the electrolyte film 3 are not formed. Only at 18 gas can enter and exit. Therefore, the fuel gas flows in one direction in the porous fuel electrode 2 as a whole.

The separator film 5 has the same thickness as the electrolyte film 3, that is, the film thickness is about several tens μm. Therefore, power loss in the separator membrane 5 can be prevented, and the power generation performance of the flat solid electrolyte fuel cell can be improved. In addition, the amount of material required for the separator film 5 can be extremely reduced as compared with the case where a conventional separator plate is used. Therefore, material cost can be reduced by reducing expensive separator materials. In the present embodiment, the separator film 5 is formed of a ceramic film such as lanthanum chromite. However, the present invention is not limited to this, and a known or new material used for the separator film 5 may be used. Also in this case, power loss in the separator membrane 5 can be prevented, and the power generation performance of the flat solid electrolyte fuel cell can be improved.

Further, in the present embodiment, the gas inflow / outflow opening 18 to the porous fuel electrode 2 is formed in advance in the single cell manufacturing stage. However, the invention is not limited to this. For example, as shown in FIG. The gas inlet / outlet may not be provided in the single cell manufacturing stage so that not only 7 but also the entire side surface of the porous fuel electrode 2 is covered with the electrolyte membrane 3. In this case, at the stage of manufacturing the single cell 1, the gas inflow / outflow opening 18 to the porous fuel electrode 2 is not formed, but at the stage of assembling the cell stack 14, the fuel gas passage 12 and the air passage 13 are formed in the manifold plate 11. At the same time, a portion of the electrolyte membrane 3 facing the fuel gas flow port 12 and the air flow port 13 may be cut off at the same time as making the holes in the manifold plate 11 to form the gas outflow / inflow opening 18.

On the other hand, as shown in FIG.
It is formed on the opposite side of the porous fuel electrode 2 across the electrolyte membrane 3. In the present embodiment, the air electrode membrane 4 is formed so as to overlap the electrolyte part 7 of the electrolyte membrane 3. The air electrode film 4 is made of a film of lanthanum strotium manganite (a compound of La, Sr, Mn, and O). This lanthanum strontium manganite is generally used as an air electrode material of a flat solid electrolyte fuel cell.

Here, the thermal expansion coefficients of the materials of the porous fuel electrode 2, the electrolyte membrane 3, the separator membrane 5, and the air electrode membrane 4 are set to be equal to each other so that each member is not damaged by thermal stress or the like. . Thereby, even if thermal expansion occurs in each member due to heat generated during operation of the fuel cell, it is possible to prevent the single cell from being damaged.

Further, the porous air electrode 6 is made of a porous plate obtained by sintering lanthanum strotium manganite. The porous plate material is formed so that air can be sufficiently circulated, and that it has sufficient strength as the single cell 1 and sufficient conductivity of electrons and oxygen ions. For this reason, since the air electrode is provided with the porous body, the contact area with the air per unit volume of the electrode member can be widened and the power generation performance can be improved. Further, since the structure of the unit cell 1 can be simplified as compared with the complicated structure of the conventional unit cell having ribs, it is not necessary to increase the assembly accuracy. Therefore, the manufacture of the cell stack 14 can be facilitated, and the strength of the cell stack 14 against thermal stress and external force can be increased.

As the material used for the air electrode membrane 4 and the porous air electrode 6, the air electrode material according to the invention which has been already filed by the present applicant is preferable. This air electrode material has an element (La)
_1-x Sr _x ) _1-y MnO _3-z and strontium dopourantan manganite satisfying 0 <x <0.2 and 0.025 <y <0.75 (see Japanese Patent Application No. 2-273174) ). According to this material, since it is single-phase and chemically stable even near the operating temperature of the fuel cell, YSZ
When the YSZ film is formed or during the power generation operation, there is no reaction product which adversely affects the power generation performance. In the present embodiment, the air electrode membrane 4 and the porous air electrode 6 are made of lanthanum strontium manganite. However, the present invention is not limited to this, and it goes without saying that any known or new air electrode material can be used. .
Also in this case, since the air electrode is formed by the air electrode film and the porous air electrode 6, the power generation performance can be improved, and the structure of the single cell 1 is simplified to have high strength against thermal stress and external force. Can be achieved.

A stack is formed by stacking the unit cells 1 configured as described above and connecting them in series. That is, a plurality of the above-mentioned unit cells 1 are stacked in series, and a conductive bonding material 9 is interposed between the porous air electrode 6 and the separator film 5 of the adjacent unit cells 1 in the stacking direction. Is formed.

The joining material 9 is made of, for example, La, Cr, Ni, O
Is made of ceramics having electronic conductivity as a main constituent element. The bonding material 9 is formed on the surface of the porous air electrode 6 on the side opposite to the air electrode film 4. This joining material 9
The separator film 5 of the unit cell 1 adjacent to the bonding member 9 is bonded to the bonding material 9 by a chemical reaction. Therefore, the contact area between the porous air electrode 6 and the separator membrane 5 can be increased, so that the electrical contact resistance between them can be reduced, and the power generation performance of the cell stack 14 can be reduced. Can be improved. In the present embodiment, the joining material 9 is made of ceramics whose main constituent elements are La, Cr, Ni, and O. However, the present invention is not limited to this, and known or new materials that can be used as a joining material having electronic conductivity. It is good. Also in this case, since the contact area between the porous air electrode 6 and the separator membrane 5 can be increased,
The power generation performance of the cell stack 14 can be improved.

Further, the cell stack 14 includes the laminate 7
And a ceramic manifold plate 1 surrounding its side to distribute fuel gas and air to each of the electrode porous bodies 2 and 6.
1 is provided. In the present embodiment, the manifold plate 1
1 is made of glass ceramics. By welding the manifold plate 11 to the side of the stacked body 7, gas sealing of the cell stack 14 is performed and the unit cells 1 are connected to each other. Here, since the manifold plate 11 is made of glass ceramic, the perforation work of the fuel gas passage 12 and the air passage 13 can be easily performed after the manifold plate 11 is attached to the laminated body 10 due to its easy-cutting property. . In the present embodiment, the manifold plate 11 is made of glass ceramic, but is not limited to this, and may be made of another ceramic. Also in this case, the perforation work can be easily performed after the manifold plate 11 is attached to the laminate 10 due to the free-cutting property of the ceramics.

A pair of manifold plates 11, 11, which face the side surfaces of the porous anode 2 of the laminate 7 that are exposed without being covered with the electrolyte membrane 3, have gas inlet / outlet openings of the porous anode 2. Fuel gas flow opening 1 opening at a position facing
2 and an air flow opening 13 which is open at a position facing the side surface of the porous air electrode 6 which is a gas inflow / outflow opening. Therefore, the fuel gas flow path and the air flow path can be made parallel. For example, if fuel gas and air are taken in from one of the set of manifold plates 11 and exhausted from the other, the flow direction of the fuel gas and air can be made the same. Also, if one of the pair of manifold plates 11, 11 is configured to inhale fuel gas to exhaust air and to exhaust fuel gas to inhale air on the other side, the flow of fuel gas and air may be reduced. The directions can be opposite.

Here, the flow of the gas inside the porous bodies 2 and 6 is in one direction from one side to the other side when viewed as a whole. 2,6
Due to the random arrangement of the small holes, the gas cannot flow straight, but is directed in each direction of up, down, left and right.

In the present embodiment, the plate members forming the unit cells 1 are installed horizontally, and the unit cells 1 are stacked in the vertical direction. Therefore, the flow directions of the fuel gas and the air are all horizontal. In the present embodiment, the respective plate members forming the single cell 1 are installed horizontally. However, the present invention is not limited to this, and each plate member forming the single cell 1 can be utilized by utilizing the fact that the single cell 1 of the present embodiment has high strength. The plate can also be installed vertically. That is,
In a conventional cell stack in which a porous body is not used for an electrode member, if each plate material is installed vertically, it may not be able to support its own weight and may be warped. Is high in strength, so that even if it is installed vertically, the strength against warpage can be improved as compared with the conventional one.
Further, in this case, the flow directions of the fuel gas and the air can be set to the same vertical direction or opposite directions. In addition, depending on the installation direction of the cell stack 14, the flow paths of the fuel gas and the air can be set obliquely in addition to horizontal and vertical.

In this embodiment, the fuel gas flow port 12 and the air flow port 13 are provided in a pair of manifold plates 11, 11, which face the porous fuel electrode 2 of the cell stack 14 and are exposed without being covered with the electrolyte membrane 3. However, the present invention is not limited to this, and as shown in FIG. 8, one set of manifold plates 1 facing the side surface where the porous fuel electrode 2 of the cell stack 14 is exposed.
Only one fuel gas flow port 12 may be formed in one, and an air flow port 13 may be formed in another set of manifold plates 11, 11. In this case, the fuel gas flow path and the air flow path can be made orthogonal to each other when the cell stack 14 is viewed from the stacking direction. When the cell stack 14 is installed with the plate members of the unit cell 1 being horizontal, the flow directions of the fuel gas and air are all horizontal. Further, when the cell stack 14 is installed with the plate members of the unit cell 1 being vertical, one of the fuel gas and the air is vertical and the other is horizontal, or both of the fuel gas and the air are horizontal. The direction becomes oblique.

A procedure for manufacturing a flat solid electrolyte fuel cell having the above-described cell stack 14 will be described below. When manufacturing the porous fuel electrode 2, nickel oxide and YSZ are mixed, and then a molding agent such as methylcellulose or polyvinyl alcohol is added and press-molded. Alternatively, the mixture of nickel oxide, YSZ, and a molding agent is extruded in a clay state. Then, the obtained molded material is 1400
The porous fuel electrode 2 is formed by sintering at about ° C. here,
The manufacturing conditions such as the pressure and the sintering temperature of the pressing and the extrusion are such that the formed porous fuel electrode 2 has a porosity that allows the fuel gas to easily pass therethrough, and the mechanical properties required for the single cell 1 Set to have strength. Here, when the mechanical strength is set to be weaker than that of a solid solid made of the material of the porous fuel electrode, the thermal stress during the power generation operation of the cell stack 14 can be absorbed and reduced. Can be improved in strength.

An electrolyte membrane 3 is formed on the obtained porous fuel electrode 2 as shown in FIG. Further, a separator film 5 is formed on the porous fuel electrode 2 as shown in FIG. As a method for forming the electrolyte membrane 3 and the separator membrane 5, any of a known wet method, a slurry coating method, a coating thermal decomposition method, a sol-gel method, and the like can be used, and is not limited to a specific method. Either method can form a film with a thickness of several tens of μm. Further, for example, it is also possible to attach the unsintered porous fuel electrode 2 to an unsintered film produced by a tape casting method, and sinter them at the same time. In this case, the number of heat treatments can be reduced, so that the manufacturing cost can be reduced.

Further, as shown in FIG. 4, an air electrode film 4 is formed on the electrolyte film 3. This film forming method is not particularly limited as in the case of the film forming method for the electrolyte membrane 3 and the like, and the various methods described above can be used.

When the porous air electrode 6 is manufactured, a molding agent such as methylcellulose or polyvinyl alcohol is added to lanthanum strotium manganite and press-formed or extruded similarly to the porous fuel electrode 2. From about 1100 to 1200 ° C. At this time,
The porous air electrode 6 is set so as to have a porosity that allows the air to easily pass through the air and the mechanical strength required for the single cell 1. Here, the sintering temperature (1100 to 1200 ° C.) of the porous air electrode 6 is lower than the sintering temperature (1400 ° C.) of the porous fuel electrode 2. Therefore, the porous air electrode 6 has lower mechanical strength than the porous fuel electrode 2 and has deformability. Thereby, the stress generated inside the cell stack 14 due to thermal stress or external force at the time of power generation can be absorbed by deformation of the porous air electrode 6 to prevent breakage.

Then, as shown in FIG. 5, the porous fuel electrode 2 is placed with the separator membrane 5 facing downward. The porous air electrode 6 is placed on the air electrode film 4 of the porous fuel electrode 2.
Further, a bonding material 9 slurried is applied to the upper surface of the porous air electrode 6. Another porous fuel electrode 2 is placed on the bonding material 9 with the separator membrane 5 facing downward. In this way, the stacked body 10 is formed by stacking the single cells 1. The number of stacked single cells 1 is set according to the voltage required for the flat solid electrolyte fuel cell to be formed.

Further, as shown in FIG. 6, two manifold plates 11 and 11 having no fuel gas circulation port 12 and no air circulation port 13 are provided on a pair of side faces located on opposite sides of the laminate 10. Contact and bundle. In this state, for example, a heat treatment at about 1100 ° C. is performed. By this heat treatment,
The laminate 10 and the manifold plate 11 can be welded and joined, and the porous air electrode 6 and the separator membrane 5 can be joined.

After the heat treatment is completed, a hole is formed in the manifold plate 11 to form the fuel gas passage 12 and the air passage 13 as shown in FIG. This drilling is performed on the laminated body 10 on which the manifold plate 11 is not provided.
Since the positions of the porous fuel electrode 2 and the porous air electrode 6 can be viewed from the side surfaces of the fuel cell, the fuel gas circulation port 12 and the air circulation port 13 can be easily formed at appropriate positions. In addition, in the present embodiment, since the manifold plate 11 is made of glass ceramics, a boring process can be easily performed by its free cutting property. For this reason, even with the manifold plate 11 attached to the laminate 10, the fuel gas passage 12 and the air passage 13 can be easily formed. Thereby, the cell stack 14 can be manufactured. In addition, in the present embodiment, since the manifold plate 11 is made of glass ceramic, the coefficient of thermal expansion can be made equal to that of the laminate 10. Therefore, it is possible to prevent the cell stack 14 from being broken due to thermal stress.

Here, when the porous fuel electrode 2 entirely covered with the electrolyte membrane 3 shown in FIG. 11 is used, the fuel gas circulation port 12 and the air circulation port 13 are formed in the manifold plate 11. At the same time, the electrolyte membrane 3 is scraped off to form a gas flow port. As shown in FIG. 8, the fuel gas passage 12 and the air passage 13 are separated from each other by a pair of manifold plates 1.
1 and 11, a set of manifold plates 11 and 11 is attached first, and the
2 and then another set of manifold plates 1
1 and 11 are attached to form an air circulation port 13. In this case, the position of the porous air electrode 6 inside the laminate 10 cannot be seen when the air flow opening 13 is perforated, but the position of the air flow opening 13 is determined based on the position of the fuel gas flow opening 12. Can be determined.

According to the cell stack 14 of the present embodiment,
Since the fuel electrode and the air electrode are formed by the porous bodies 2 and 6 and the fuel gas or air is circulated inside, the contact between the electrode member and the gas per unit volume of the electrode member is smaller than that of the conventional flat plate-shaped electrode plate. The area can be increased. Therefore, it is possible to improve the power generation performance by increasing the number of electrode reaction fields. Further, the rib of the separator used in the conventional flat plate type structure can be eliminated. Therefore, it is not necessary to increase the assembling accuracy by simplification of the structure of the single cell 1, so that the production of the cell stack 14 is facilitated and the strength against thermal stress and external force can be enhanced. As a result, the size of the cell stack 14 can be increased, so that the power generation performance can be improved.

Further, according to the cell stack 14 of the present embodiment, the porous air electrode 6 is formed to be soft enough to absorb the thermal stress, so that it is easily deformed by the thermal stress and the external force of the cell stack 14. High flexibility that can follow the requirement can be achieved. And the cell stack 14
Can be maintained in a high strength regardless of whether it is installed vertically or horizontally. In addition, in the conventional stacking of flat cells, high processing accuracy is required to prevent breakage due to stress during manufacturing and power generation.
According to this, high processing accuracy is not required, so that quality control can be easily performed.

Further, according to the cell stack 14 of the present embodiment, since the separator is formed of a film, the amount of expensive separator material used can be reduced.
Therefore, the cost of the cell stack 14 can be reduced.

Further, according to the cell stack 14 of the present embodiment, since the separator film 5 is formed directly on the porous fuel electrode 2, the contact area between the porous fuel electrode 2 and the separator film 5 can be increased. Can be. For this reason, the electrical contact resistance between the fuel electrode and the separator, which has been a problem in the past, can be significantly reduced, and the power generation performance can be improved.

The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this embodiment, and various modifications can be made without departing from the gist of the present invention. For example, the single cell 1 of the present embodiment has a porous fuel electrode 2
An electrolyte membrane 3, a separator membrane 5, and an air electrode membrane 4 are formed on the substrate, and a porous air electrode 6 is laminated thereon. However, the present invention is not limited to this, and as shown in FIG. The electrolyte membrane 3, the separator membrane 5, and the fuel electrode film 16 may be formed, and the porous fuel electrode 17 may be laminated thereon.

More specifically, the porous air electrode 15 is made of, for example, a porous plate obtained by sintering lanthanum strotium manganite. The electrolyte membrane 3 and the separator membrane 5 are formed on the porous air electrode 15. The materials and the method of forming the electrolyte membrane 3 and the separator membrane 5 are the same as those for the porous fuel electrode 2 described above, and therefore the description is omitted. Further, the porous air electrode 15 is formed with a sealing portion 8 composed of an edge film portion 8a and a corner film portion 8b of the electrolyte membrane 3, similarly to the porous fuel electrode 2 of FIG. here,
The fuel electrode film 16 is made of a porous plate material obtained by mixing nickel and YSZ and sintering them. Further, the porous fuel electrode 17 is made of a porous plate material obtained by sintering a mixture of nickel and YSZ. In this embodiment, the porous fuel electrode 17 is a porous plate material obtained by sintering a mixture of nickel and YSZ. However, the present invention is not limited to this. For example, the porous fuel electrode 17 may be formed of nickel felt.

Then, a plurality of the unit cells 1 described above are stacked in series, and a conductive bonding material 9 is interposed between the porous air electrode 15 and the separator film 5 of the unit cells 1 adjacent in the stacking direction. A laminate 10 is formed. This laminate 10
And the same manifold plate 1 as the cell stack 14 described above.
1 to form a cell stack 14.

The cell stack 1 of the embodiment shown in FIG.
Also, according to the fourth embodiment, the fuel electrode and the air electrode are formed into porous bodies 15 and 17 as fuel gas or air passages in the same manner as in the embodiment shown in FIG. The power generation performance can be improved by increasing the contact area. In addition, since the ribs of the separator can be omitted, the production of the cell stack 14 is facilitated and the strength against thermal stress and external force can be increased. Furthermore, since the porous fuel electrode 17 is formed to be soft enough to absorb the stress, it follows the thermal stress and the external force of the cell stack 14 in any direction by deformation, thereby securing high flexibility and ensuring high flexibility. Strength can be improved, and high processing accuracy is not required, and quality control can be easily performed. In addition, since the separator is formed of a film, the cost of the cell stack 14 can be reduced. Furthermore, since the separator film 5 is directly formed on the porous air electrode 15, the contact area between the porous air electrode 15 and the separator film 5 can be increased, and the power generation performance can be improved.

In each of the above-described embodiments, the cell stack 14 includes the stacked body 10 in which a plurality of single cells 1 are stacked. However, the present invention is not limited to this. 14 may be formed. Also in this case, since the fuel electrode and the air electrode are made porous and the fuel gas or air is circulated inside, the contact area between the gas and the electrode member can be widened to improve the power generation performance. The same effects as those of the above-described embodiments can be obtained.

In the present embodiment, the sealing portion 8 of the electrolyte membrane 3
Is composed of an edge film portion 8a and a corner film portion 8b, but is not particularly limited thereto. For example, as shown in FIG. Only the seal portion 8a that covers the edge of the portion 7 may be formed. In this case, a seal portion 8a may be formed on the entire side surface of the porous fuel electrode 2 as shown in FIG.
Further, as in the case of the edge film portion 8a shown in FIG. 2, the entire edge portion of the side surface near the electrolyte portion 7 may be covered.

[0058]

As is apparent from the above description, according to the single cell of the flat solid electrolyte fuel cell according to the first or second aspect, the fuel electrode and the air electrode are formed of a porous material. The gas can contact and react with the electrode members while flowing inside each electrode member. For this reason, there is no need to provide ribs or the like for forming the gas flow path, so that the structure of the single cell can be simplified and the strength can be improved. As a result, the size of the single cell can be increased, so that the power generation characteristics can be improved.

Since the fuel electrode and the air electrode are made of a porous material, they can be made softer than a solid solid made of the material of each electrode member. For this reason, since the thermal stress at the time of the power generation operation of the cell stack in which the single cells are stacked can be absorbed and reduced, the flexibility of the cell stack can be improved and the strength can be improved. In addition, since high processing accuracy of a single cell for preventing damage due to thermal stress is not required, manufacturing cost can be reduced and quality control can be easily performed.

Further, since the gas is circulated inside the porous body, the contact area with the gas per unit volume of the electrode member can be increased. For this reason, the power generation performance in a single cell can be improved.

Further, since the separator is directly formed on the fuel electrode or the air electrode made of a porous material, the separator film enters into a large number of minute holes of the fuel electrode or the air electrode, and the separator film enters between them. The contact area can be increased. For this reason, the contact resistance between the fuel electrode or the air electrode and the separator can be significantly reduced, and the power generation performance can be improved.

Moreover, since both the separator and the electrolyte are membranes, the power loss due to their internal resistance can be reduced. Thereby, power generation performance can be improved. Further, since the separator is formed of a membrane, the amount of expensive separator material used can be reduced. Therefore, the manufacturing cost of the single cell can be reduced.

In the cell stack of the flat type solid electrolyte fuel cell according to the third aspect, the single cells according to the first or second aspect are stacked in series, and a conductive property is provided between adjacent single cells in the stacking direction. Is provided, the contact area between the porous body and the separator membrane can be increased. For this reason, the electrical contact resistance between them can be reduced, and the power generation performance by the cell stack can be improved.

Furthermore, in the cell stack of the flat solid electrolyte fuel cell according to the fourth aspect, since the ceramic manifold plate surrounding the laminate is provided, the laminate is assembled and the manifold plate is provided around the laminate. Gas flow holes can be drilled. Here, since this perforation work can be performed by attaching the manifold plate to the laminate and then checking the position where the hole is to be formed by looking at the side surface of the laminate where the manifold plate is not attached, the through-hole is previously formed in the manifold plate. It is not necessary to form the through hole, and the accuracy of the position of the through hole can be easily improved. For this reason, it is not necessary to previously form the flow holes in the manifold plate before mounting based on the actually measured values of the laminate as in the related art, so that high processing accuracy can be eliminated. As a result, the manufacturing cost can be reduced and quality control can be easily performed.

Moreover, since the manifold plate is made of ceramics, the thermal expansion coefficient can be made equal to that of the laminate. For this reason, the generation of thermal stress during power generation or the like can be suppressed to prevent the cell stack from being broken.

[Brief description of the drawings]

FIG. 1 is a side view showing a cell stack of a flat solid electrolyte fuel cell according to the present invention.

FIG. 2 is a perspective view showing a state in which an electrolyte membrane is formed on a porous fuel electrode.

FIG. 3 is a perspective view showing a state in which a separator membrane is formed on the porous fuel electrode shown in FIG.

FIG. 4 is a perspective view showing a state in which an air electrode film is formed on the porous fuel electrode shown in FIG.

FIG. 5 is a perspective view illustrating a state in which a single cell is stacked to form a stacked body.

FIG. 6 is a perspective view showing a state in which a manifold plate is attached to a laminate.

FIG. 7 is a perspective view showing a cell stack of the flat solid electrolyte fuel cell of the present invention.

FIG. 8 is a perspective view showing another embodiment of the cell stack of the flat solid electrolyte fuel cell.

FIG. 9 is a perspective view showing another embodiment of the laminate.

FIG. 10 is a perspective view showing another embodiment of the electrolyte membrane.

FIG. 11 is a perspective view showing another embodiment of the electrolyte membrane.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single cell 2 Porous fuel electrode 3 Electrolyte film 4 Air electrode film 5 Separator film 6 Porous air electrode 9 Joining material 11 Manifold plate 14 Cell stack 15 Porous air electrode 16 Fuel electrode film 17 Porous fuel electrode

Claims (4)

[Claims] A fuel electrode comprising a porous body; an electrolyte film formed on one of the front surface and the back surface of the fuel electrode; an air electrode film formed on the electrolyte film; A flat cell type solid electrolyte fuel cell, comprising: a separator film formed on the other surface of the above; and an air electrode made of a porous material bonded to the air electrode film. 2. An air electrode made of a porous material, an electrolyte film formed on one of the front and back surfaces of the air electrode, a fuel electrode film formed on the electrolyte film, and the air electrode A flat cell type solid electrolyte fuel cell, comprising: a separator film formed on the other surface of the fuel cell; and a fuel electrode made of a porous material bonded to the fuel electrode film. 3. A laminated body comprising the unit cells according to claim 1 or 2 stacked in series, and having a conductive bonding material interposed between the unit cells adjacent in the stacking direction. A cell stack of a flat solid electrolyte fuel cell. 4. The cell stack of a flat solid electrolyte fuel cell according to claim 3, wherein a ceramic manifold plate is provided for the laminate.