JP2003272668A - Fuel battery cell and cell stack as well as fuel battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel battery cell, and a cell stack as well as a fuel battery, capable of improving a power-generating capacity per unit cell, easy to manufacture, with improved reliability, and capable of reducing a stack volume per a given power generation volume. <P>SOLUTION: A circular solid electrolyte 37 is fitted around an outer periphery face of a planiform fuel side electrode 35 so as to surround the fuel side electrode 35, and a circular oxygen side electrode 39 is fitted on an outer periphery face of the solid electrolyte 37 so as to surround the solid electrolyte 37. The planiform shape is structured of a pair of flat parts 34a formed almost in parallel and an arc-shaped part 35b connecting both end parts of the flat parts 34a. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell, a cell stack and a fuel cell, and more particularly to a fuel cell, a cell stack and a fuel cell capable of improving power generation.

[0002]

2. Description of the Related Art In recent years, various fuel cells in which a stack of fuel cells are housed in a container have been proposed as next-generation energy.

FIG. 8 shows a cell stack of a conventional solid oxide fuel cell unit. In this cell stack, a plurality of fuel cell units 1 (1a, 1b) are assembled into one fuel cell unit 1a and the other fuel cell unit 1a. The current collecting member 5 made of metal felt is interposed between the fuel cell 1b and the other fuel cell 1b, and the inner electrode 7 of one fuel cell 1a and the outer electrode 11 of the other fuel cell 1b are electrically connected in series. Was configured.

In the fuel cell 1 (1a, 1b), a solid electrolyte 9 and an outer electrode 11 are provided on the outer peripheral surface of a cylindrical inner electrode 7.
The inner connector 7 exposed from the solid electrolyte 9 and the outer electrode 11 is provided with an interconnector 13 so as not to be connected to the outer electrode 11.

The interconnector 13 has an inner electrode 7
In order to reliably shut off the gas flowing inside the gas from the gas flowing outside the outer electrode 11, a dense conductive ceramic is used which is not easily altered by the fuel gas and the oxygen-containing gas.

The electrical connection between one fuel cell 1a and the other fuel cell 1b will be specifically described. The inner electrode 7 of one fuel cell 1a is connected to the interconnector 13 provided on the inner electrode 7. It was carried out by connecting to the outer electrode 11 of the other fuel cell 1b through the current collecting member 5.

FIG. 9 shows a cell stack of a conventional solid electrolyte type fuel cell of an interconnectorless type.
This cell stack includes a plurality of fuel cells 2 (2a, 2a
b) is assembled, and the cell 2 is formed by forming the solid electrolyte 19 on the entire circumferential surface of the cylindrical inner electrode 17 and forming the outer electrode 21w on the entire circumferential surface of the solid electrolyte 19. ing.

In each of the left and right fuel battery cell rows, a current collecting member 23 made of metal felt or the like for connecting the outer electrodes 21 is interposed between the one fuel battery cell 2a and the other fuel battery cell 2b. The inner electrodes 17 were electrically connected to each other, and the outer electrode 21 of the left fuel cell array and the inner electrode 17 of the right fuel cell array were electrically connected.

FIG. 10 shows a cell stack of a flat solid oxide fuel cell unit. This cell stack is formed by assembling a plurality of fuel cell units 3 (3a, 3b).
A current collecting member 25 made of metal felt or the like is interposed between one fuel battery cell 3a and the other fuel battery cell 3b, and an inner electrode 27 of one fuel battery cell 3a and an outer electrode of the other fuel battery cell 3b. 31 was electrically connected.

The fuel cell 3 (3a, 3b) is formed by sequentially providing a solid electrolyte 29 and an outer electrode 31 on the outer peripheral surface of a flat inner electrode 27, and is exposed from the solid electrolyte 29 and the outer electrode 31. The outer electrode 3 is attached to the inner electrode 27
An interconnector 33 is provided so as not to be connected to 1. A plurality of gas passage holes 32 are formed in the inner electrode 27.

The electrical connection between the one fuel battery cell 3a and the other fuel battery cell 3b is performed by connecting the inner electrode 27 of the one fuel battery cell 3a to the interconnector 33 provided on the inner electrode 27 and a current collecting member. It was carried out by connecting to the outer electrode 31 of the other fuel cell 3b via 25.

[0012]

However, in the fuel cell of FIG. 8, since the portion where the interconnector 13 is formed does not generate power, there is a drawback that about 20% of the entire circumference does not contribute to power generation.

Further, in the fuel cell of the interconnectorless type shown in FIG. 9, the inner electrode, the solid electrolyte and the outer electrode are formed on the entire circumference of the cell as compared with the cell shown in FIG. Although it has advantages, its effect is only improved by about 20% compared to the case of FIG.
It does not lead to a dramatic increase in the amount of power generation per unit cell.

Further, in the flat fuel cell of FIG. 10, the unit cell can be made larger than that of the cell of FIG. 8 so that the power generation amount per unit cell increases, but the portion where the interconnector is formed does not generate power. Therefore, about 40% of the entire circumference did not contribute to power generation, and the advantage of this shape was not fully utilized.

Further, although the interconnectors 13 and 33 are provided in FIGS. 8 and 10, the interconnectors 13 and 3 are provided.
3 is required to reliably block the gas flowing inside the inner electrodes 7 and 27 and the gas flowing outside the outer electrodes 11 and 31 and to be not deteriorated by the fuel gas and the oxygen-containing gas. There is a problem in that long-term reliability is low because it takes time to manufacture and the possibility of gas leakage cannot be abandoned.

Further, a solid oxide fuel cell (SOFC)
In the above, since it is necessary to heat the power generation cell to a high temperature of 600 to 1000 ° C. due to the characteristics of the solid electrolyte, it is necessary to reduce the volume of the heated portion. The smaller the volume of the heated portion, the smaller the energy consumed for heating the cell at the time of start-up or steady operation, so that the start-up becomes faster and the power generation efficiency can be increased. For these reasons, particularly in a solid oxide fuel cell (SOFC), not only the power generation amount of a single cell but also the reduction of the stack volume per a predetermined power generation amount is an important factor.

That is, when the cylindrical type interconnectorless type cell of FIG. 9 is used, although there are some improvements, a large number of cells are required to generate a predetermined amount of power, and the stack volume is large accordingly. In addition, since many cells are required, the reliability tends to decrease.

In the flat fuel cell shown in FIG. 10, the amount of power generation per cell can be increased by increasing the size (widening the width) of the fuel cell.
Since about 40% of the entire circumference is a non-power generation portion due to the formation, many cells are required to generate a predetermined amount of power, the stack volume increases, and the connection reliability tends to decrease accordingly.

The present invention provides a fuel cell, a cell stack, and a fuel cell that can improve the amount of power generation per unit cell, can be easily manufactured, can improve reliability, and can reduce the stack volume per predetermined amount of power generation. The purpose is to provide.

[0020]

In the fuel cell of the present invention, an annular solid electrolyte is provided on the outer surface of a flat inner electrode so as to surround the inner electrode, and the solid electrolyte is provided on the outer surface of the solid electrolyte. It is characterized in that an annular outer electrode is provided so as to surround the.

In such a fuel cell, since the annular solid electrolyte and the outer electrode are sequentially formed on the outer peripheral surface of the inner electrode and the interconnector is not formed, the manufacturing is easy and the entire circumference of the cell is Can be the power generation section,
It is possible to effectively use the entire circumference of the cells to generate power, and increase the amount of power generation per fuel cell, and as a result, it is possible to reduce the number of cells required per predetermined amount of power generation. Further, as the number of cells decreases, the total number of connections between cells decreases, and the total number of connecting parts that may cause a failure can be reduced, so that reliability is improved.

Further, by forming a solid electrolyte and an outer electrode on a flat inner electrode to form a flat cell,
The amount of power generation per fuel cell can be increased by making the cell larger (wider), but even if the cell is made larger in this way, the stack volume required to generate a certain amount of power will be larger than in the past. The size of the fuel cell can be made smaller, and the volume of the heated part required can be reduced, the energy used for heating the cell at the time of startup or steady operation can be minimized, and the startup can be accelerated.
The power generation efficiency can be improved.

Further, the fuel cell of the present invention is preferably a flat shape composed of a pair of flat portions formed substantially parallel to each other and an arcuate portion connecting the end portions of the flat portions.

In the fuel cell having such a structure, the stack volume required to generate a predetermined amount of power can be minimized, and the stress generated in the solid electrolyte and the external electrode in the arcuate portion can be suppressed, resulting in peeling and peeling. Generation of cracks can be suppressed.

That is, the fuel cells are arranged in the storage container so that the flat portions of the adjacent cells are opposed to each other. For example, when the flat portions are connected (parallel connection), they are connected via a conductive member. Since the cells can be connected in the entire flat part, the connection reliability can be improved, and the reliability can be improved to reduce the distance between the cells. On the other hand, when connecting in series, the flat parts are connected to each other. However, since the facing surfaces of the cells are flat, the distance between the cells can be reduced and the stack volume can be reduced.

The fuel cell of the present invention has a minor axis R1.
It is desirable that the ratio R2 / R1 of the long diameter R2 is 2 or more. As a result, the amount of power generation per cell can be increased, so that the number of cells required to generate a predetermined amount of power can be reduced and the number of connections between cells can be reduced.

It is desirable that the minor axis R1 is 10 mm or less. As a result, the stack volume required to generate a predetermined amount of power can be further reduced.

In the fuel cell of the present invention, it is desirable that at least one gas passage hole is formed in the inner electrode in the axial direction. This ensures the gas flow in the inner electrode.

Further, in the fuel cell of the present invention, it is desirable that a conductive member which is electrically connected to the inner electrode is provided in the gas passage hole of the inner electrode. The outer surface of the fuel cell is an interconnectorless type in which an interconnector that connects the cells is not formed, but by electrically connecting the conductive member to the inner electrode, a current is transmitted from the inner electrode through the conductive member. You can take it out.

A long conductive member is inserted into the gas passage hole of the inner electrode, and the long conductive member and the inner electrode are provided between the long conductive member and the inner surface of the inner electrode. It is desirable to provide a conductive member for connection for electrically connecting with. Thereby, the electric current can be taken out from the elongated conductive member via the conductive member for connection which is electrically connected to the inner electrode.

The cell stack of the present invention comprises a plurality of the above fuel cells. In such a cell stack, since the amount of power generation per cell can be increased, the number of cells required to generate a predetermined amount of power can be reduced,
Moreover, since the cell shape is flat, the stack volume for obtaining a predetermined amount of power generation can be reduced.

Further, the fuel cell of the present invention comprises a plurality of the above-mentioned fuel cells stored in a storage container. In such a fuel cell, downsizing can be achieved and manufacturing cost can be reduced.
It is possible to improve power generation efficiency, mountability, mount reliability, and maintainability.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a fuel cell of the present invention. (A) is a cross-sectional view and (b) is a perspective view.
The fuel cell 34 of the present invention has a flat shape with no interconnector, and a dense solid material is formed on the entire outer peripheral surface of the fuel-side electrode (inner electrode) 35 containing a flat and porous metal as a main component. An electrolyte 37 is formed, and an oxygen-side electrode (outer electrode) 39 made of porous conductive ceramics is sequentially laminated on the entire outer peripheral surface of the solid electrolyte 37. The fuel-side electrode 35 serves as a support. ing.

That is, in the fuel cell 34, an annular solid electrolyte 37 is provided on the outer surface of the flat fuel-side electrode 35 so as to surround the fuel-side electrode 35.
An annular oxygen-side electrode 39 is provided on the outer surface of the so as to surround the solid electrolyte 37. The fuel electrode 35 has one fuel gas passage hole 41 formed in the axial direction. It should be noted that when manufacturing a fuel cell, the cells are supported and fixed, but the oxygen side electrode 39 may not be formed in this supported and fixed portion.

The fuel-side electrode 35 is provided with a pair of flat portions 35a provided so as to face each other substantially in parallel, and an arcuate portion 35b provided at both ends in the width direction so as to smoothly connect the end portions of the pair of flat portions 35a. And the arcuate portions 35b are arcuate shapes projecting outward.
Inside the fuel-side electrode 35, one gas passage hole 41 having a cross-sectional shape similar to the outer shape is formed.

The fuel cell unit 34 has a pair of flat portions 34a whose outer shapes are formed substantially parallel to each other and a pair of flat portions 34a formed at both ends of the flat portions 34a, depending on the shape of the fuel-side electrode 35. It is composed of an arc-shaped portion 34b that connects the ends of the flat portion 34a.

2A and 2B show another fuel cell 43 of the present invention. FIG. 2A is a transverse sectional view and FIG. 2B is a perspective view.
In this fuel battery cell 43, except that a plurality of fuel gas passage holes 45 are formed in the fuel side electrode 44 in the axial direction,
It has the same structure as in FIG. Reference numeral 46 is a solid electrolyte, 47 is an oxygen side electrode, 43a is a flat portion of the fuel cell 43, 43b is an arcuate portion of the fuel cell 43, 44a is a flat portion of the fuel side electrode 44, and 44b is a fuel side electrode 44. Shows the arcuate portion of.

FIG. 3 shows another fuel cell 4 according to the present invention.
In this fuel cell 49, except that an annular solid electrolyte 53 and an oxygen side electrode 55 are formed on a part of the outer peripheral surface of the fuel side electrode 51 in the axial direction,
It has the same structure as in FIG. Therefore, the fuel-side electrode 51 projects from one end of the fuel cell 49.
Reference numeral 57 indicates a fuel gas passage hole, 49a indicates a flat portion of the fuel cell 49, and 49b indicates an arc-shaped portion of the fuel cell 49.

The fuel side electrodes 35, 44, 51 are made of Ni, C
o, Ti, or Ru containing any one kind of metal or metal oxide, or an alloy or alloy oxide thereof as a main component, and other than these, a solid electrolyte 37 on the outer surface,
46, 55 to improve the bonding strength, solid electrolyte 37, 4
In order to approximate the thermal expansion coefficient of 6,55, 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.
When the fuel-side electrode is made of metal oxide, it is reduced in a reducing atmosphere to generate electricity.

The ratio R2 / R1 of the minor axis R1 and the major axis R2 of the fuel cell of FIGS. 1 to 3 is preferably 2 or more. As a result, the number of cells required to generate a predetermined amount of power can be reduced. In particular, R2 / R1 is preferably 4 or more, and more preferably 8 or more.

The fuel cells 34, 43, 49 have a pair of flat portions 34a, 43a, 49a as described above.
And the flat portions 34a, 43a, 49a are formed into a flat elliptical shape including arc-shaped portions 34b, 43b, 49b that smoothly connect both ends of the flat portions 34a, 43a, 49a.
The distance between 4a, 43a and 49a was defined as the minor axis R1, and the maximum distance in the direction perpendicular to this minor axis R1 was defined as the major axis R2.

The minor axis R1 of the fuel cell is preferably 10 mm or less. As a result, the volume of the fuel cell unit can be reduced and the power density per volume can be improved. In particular, it is preferably 8 mm or less, more preferably 6 mm or less.

The solid electrolytes 37, 46, 55 provided on the outer surfaces of the fuel side electrodes 35, 44, 51 are made of partially stabilized or stabilized ZrO ₂ containing 3 to 15 mol% Y and a rare earth element. Dense ceramics are used. Fuel-side electrodes 35, 44, 51 and solid electrolyte 3
A bonding layer composed of a dense layer may be interposed between 7, 46 and 55 to improve the bonding strength. The thickness of the solid electrolytes 37, 46 and 55 is preferably 10 to 100 μm from the viewpoint of preventing gas permeation.

The oxygen side electrodes 39, 47 and 55 are made of LaMn.
It is composed of at least one kind of porous conductive ceramics of O ₃ based material, LaFeO ₃ based material, and LaCoO ₃ based material. The oxygen side electrodes 39, 47, 55 are 600-
The LaFeO ₃ -based material is desirable because it has high electric conductivity at a relatively low temperature of about 1000 ° C. Oxygen side electrode 3
The thickness of 9, 47, 55 is 30 to 1 from the viewpoint of current collecting property.
It is preferably 00 μm.

A method for manufacturing the above fuel cell will be described. First, for example, a fuel-side electrode material obtained by mixing NiO powder, ZrO ₂ (YSZ) powder containing Y, an organic binder, and a solvent is extruded to form a fuel gas passage hole in the axial direction. A flat fuel-side electrode molded body is prepared and dried.

Next, for example, a sheet-shaped molded body is prepared by using a solid electrolyte material in which YSZ powder, an organic binder and a solvent are mixed, and the sheet-shaped molded body is formed on the fuel-side electrode molded body. Wrap and dry so that both ends overlap and do not separate.

Next, the laminated compact was subjected to binder removal treatment and co-fired at 1300 to 1600 ° C. in an oxygen-containing atmosphere,
This laminated body is dipped in a paste containing, for example, a LaFeO ₃ material and a solvent, and an oxygen-side electrode molded body is formed on the surface of the solid electrolyte by dipping.
The fuel cell of the present invention can be produced by baking at 1300 ° C.

A solid electrolyte sheet-shaped compact may be formed on the surface of the fuel-side electrode compact, and then an oxygen-side electrode compact may be formed, followed by simultaneous firing. Also, the fuel-side electrode molded body is dipped in a slurry containing the solid electrolyte material and dried, and further, this is dipped in a slurry containing the oxygen-side electrode material, dried, and co-fired. good.

In the fuel cell constructed as described above, the annular solid electrolytes 37, 46 are formed on the outer surfaces of the flat fuel-side electrodes 35, 41, 47 so as to surround the fuel-side electrodes 35, 44, 51. , 55, and the solid electrolyte 3
On the outer surface of 7, 46, 55, the solid electrolytes 37, 46, 55
The annular oxygen-side electrodes 39, 47, 55 are provided so as to surround the fuel-side electrodes, and the annular solid electrolytes 37, 46, 55, the oxygen-side electrodes 39, 47, 5 are provided on the outer peripheral surfaces of the fuel-side electrodes 35, 44, 51.
5 is formed without forming the interconnector, the manufacturing is easy, and the entire circumference of the cell can be used as a power generation portion. The amount of power generation per body is increased, and as a result, the number of cells required to obtain a predetermined amount of power generation can be reduced.

Further, as the number of cells decreases, the total number of connections between cells also decreases, and the number of connecting parts that may cause a failure can be reduced, so that mounting reliability can be improved.

Further, the flat fuel side electrodes 35, 44,
51 is a solid electrolyte 37, 46, 55, an oxygen side electrode 39,
By forming 47 and 55 and forming flat cells, the stack volume required to generate a predetermined amount of power can be made smaller than before, the required heated part volume can be reduced, and at the time of startup or steady operation. The energy required for heating the cell during operation can be reduced.

FIG. 4 shows a cell stack of the present invention formed by using the fuel cell of FIG. As shown in FIG. 4, the cell stack is composed of a plurality of the fuel cells shown in FIG. As shown in FIGS. 4 and 5B, in the fuel cell 34 of this cell stack, an inner elongated conductive member 61 is inserted into the center portion of the fuel gas passage hole 41 of the fuel-side electrode 35. An inner elongated conductive member 61 is provided between the elongated conductive member 61 and the inner surface of the fuel electrode 35.
A conductive member 63 for connection is provided to electrically connect the fuel electrode 35 to the fuel electrode 35.

The inner elongated conductive member 61 has a conductive rod shape or a plate shape, and the connecting conductive member 63 is made of Ni felt so that fuel gas can pass therethrough. The inner elongated conductive member 61 and the connecting conductive member 63 do not necessarily need to be made of Ni.

An outer elongated conductive member 65 is provided on the outer surface of the oxygen-side electrode 39 corresponding to the flat portion 34a of the fuel cell 34 and is electrically connected thereto. The outer long conductive member 65 may be formed on a part of the oxygen-side electrode 39 or may be formed on the entire surface.

Adjacent fuel cells 34 are connected to each other by connecting an inner long conductive member 61 of one fuel cell 34 and an outer long conductive member 65 of the other fuel cell 34 to each other. The cells 34 are electrically connected in series.

The outer elongated conductive member 65 is made of at least one of Pt, Ag, Ni-based alloy and Fe-Cr steel alloy from the viewpoint of having heat resistance, oxidation resistance and electric conductivity during power generation. Is desirable.

As shown in FIG. 5A, the connecting conductive member 63 made of Ni felt is inserted into the fuel gas passage hole 41 of the fuel electrode 35 without inserting the inner elongated conductive member. Although it may be provided, from the viewpoint of current collection property, as shown in FIG.
It is desirable to insert the inner elongated conductive member 61 as shown in (b).

Further, as shown in FIG. 5C, both ends of the inner elongated conductive member 61 may be projected outward from both ends of the fuel cell unit 34. In this case,
Current can be drawn from both sides of the cell.

The fuel cell 43 shown in FIG. 2 may also have the cell stack structure shown in FIGS. 4 and 5. In this case, the inner elongated conductive member may be inserted into all of the plurality of fuel gas passage holes 45, or may be inserted into some of the fuel gas passage holes 45. Further, in the fuel cell 49 shown in FIG. 3, since one of the fuel-side electrodes 51 is exposed, in addition to the cell stack structure as shown in FIGS. Electric power can be taken out by using the fuel side electrode 51 without using a conductive member.

The fuel cell of the present invention is constructed by accommodating the above cell stack in an accommodating container. That is, the storage container is provided with a supply pipe for introducing an oxygen-containing gas (air) and a supply pipe for introducing a fuel gas into the cell stack, and the oxygen-containing gas flows along the oxygen-side electrode of the fuel cell unit. At the same time, the fuel gas is caused to flow along the fuel side electrode,
For example, the fuel cell unit starts power generation by heating to about 1000 ° C.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention. For example, the oxygen-side electrode may be the inner electrode.

[0062]

EXAMPLES First, NiO powder having an average particle size of 0.5 μm,
ZrO containing 8 mol% Y and having an average particle size of 0.5 μm
₂ (YSZ) powder, an organic binder composed of a pore agent and PVA, and a solvent composed of water are mixed by extrusion molding to prepare a flat fuel-side electrode molded body,
It was dried.

Next, a sheet-shaped molded body was prepared using a solid electrolyte material obtained by mixing the YSZ powder, an organic binder made of an acrylic resin, and a solvent made of toluene. Wrap it on the electrode molded body so that both ends overlap and do not separate, and dry,
A laminated molded body was produced by stacking a sheet-shaped molded body of a solid electrolyte on the fuel-side electrode molded body.

Next, the laminated molded body was subjected to a binder removal treatment and cofired at 1500 ° C. in the atmosphere. This laminated body was laminated with La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O having an average particle diameter of 2 μm.
₃ powder and dipping in a paste containing a solvent consisting of normal paraffin, an oxygen-side electrode molded body is prepared by dipping on the surface of the solid electrolyte and baked at 1150 ° C. to form an oxygen-side electrode, as shown in FIG. A fuel cell of the present invention was produced.

By changing the minor axis and major axis of the fuel electrode, the minor axis R1 and major axis R2 of the fuel cell were varied to produce fuel cell cells having different R2 / R1 ratios.

Next, Pt having an oxidation resistance for the oxygen side electrode
An outer long conductive member made of a system metal is connected, and an inner long conductive member is inserted in the center of the fuel gas passage hole in the fuel side electrode of the created cell. The side electrode was connected with a connecting conductive member made of Ni felt to fabricate a cell as shown in FIG. 5 (b).

The produced fuel cell was heated to 900 ° C., hydrogen gas was passed through the fuel gas passage hole in the fuel side electrode, and air was passed outside the fuel cell to generate electricity per cell. Was measured. Based on this measurement result,
The number of cells required to obtain a power generation amount of 1.5 KW and the volume of the cell stack formed by the required number of cells were determined. At this time, in order to prevent an electrical short circuit, or from the viewpoint of fabrication, a space of 6 mm was required on the outer circumference of the cell, and the calculation was performed. The results are shown in FIG.

FIG. 6 shows the relationship between the minor axis R1, the R2 / R1 ratio and the volume of the cell stack, which is necessary for obtaining a power generation amount of 1.5 KW in a cylindrical cell having a diameter of 4 mm. The stack volume when using the number of cells is 100,000
And In FIG. 6, the point of R2 / R1 = 1 shows the result of the cylindrical cell.

From the results shown in FIG. 6, when the minor axis R1 is 20 mm, the volume tends to increase with an increase in the R2 / R1 ratio, there is no effect of reducing the volume of the heated portion of the cell stack, and the thermal efficiency is Rather, it can be seen that it tends to decline.
It can be seen that when R1 is 10 mm, the volume is slightly reduced as the R2 / R1 ratio is increased.

Further, when R1 is 8 mm or less, R2
It is clear that the volume decreases with increasing / R1 ratio. It can be seen that in the cell with R1 of 4 mm, when the R2 / R1 ratio is 8, the volume can be reduced by about 35% as compared with the cylindrical shape. Therefore, from this result, it is understood that the stack volume can be reduced by setting R1 to 10 mm or less and the R2 / R1 ratio to 2 or more.

FIG. 7 shows the relationship between the minor axis R1, the R2 / R1 ratio and the number of cells. It can be seen from FIG. 7 that the larger the R1, the smaller the number of cells. However, R1 is 2
In the case of 0 mm, there is no effect of reducing the volume from the result of FIG.

For cells with R1 of 10 mm or less, R
1, the number of cells tends to decrease as the R2 / R1 ratio increases, but in the case of a cell with R1 of 4 mm, R2 /
It can be seen that when the R1 ratio is 8, the number of cells is 1/5 or less compared to when R2 / R1 is 1, and the number of cells can be significantly reduced. Therefore, from the results of FIG. 6 and FIG.
It is possible to reduce the volume of the heated portion and further reduce the number of cells at the same time by setting the ratio to be equal to or less than mm and setting the R2 / R1 ratio to 2 or more, that is, by making the cell shape flat. For example, in the case of a cell with R1 of 4 mm, when the R2 / R1 ratio is 8, the volume can be 70% compared with the case where a cell with an R2 / R1 ratio of 1 is used. Can be reduced to 1/5 or less.

[0073]

EFFECTS OF THE INVENTION In the fuel cell of the present invention, the cell shape is made flat and the interconnectorless type is adopted, so that the production is easy and the power generation amount as a single cell can be improved, and the desired power generation amount can be obtained. On the other hand, it is possible to simultaneously reduce the number of cells, the volume that requires heating including the cell power generation unit and its peripheral members, and reduce the manufacturing cost.
It is possible to improve power generation efficiency, mountability, mount reliability, and maintainability.

[Brief description of drawings]

FIG. 1 shows a fuel cell of the present invention having one gas passage hole, (a) is a cross-sectional view and (b) is a perspective view.

2A and 2B show a fuel cell of the present invention in which a plurality of gas passage holes are formed, wherein FIG. 2A is a cross-sectional view and FIG. 2B is a perspective view.

FIG. 3 is a perspective view showing a fuel cell of the present invention in which a plurality of gas passage holes are formed and inner electrodes are projected.

FIG. 4 is a cross-sectional view showing a cell stack of the present invention.

FIG. 5 (a) is a vertical cross-sectional view of a fuel cell in which a conductive member for connection is inserted in a gas passage hole, and FIG. 5 (b) shows an inner elongated conductive member and a conductive member for connection arranged in the gas passage hole. 2C is a vertical cross-sectional view of the fuel cell, and FIG. 3C is a vertical cross-sectional view of the fuel cell in which the inner long conductive member is projected on both sides.

FIG. 6 is a ratio of the minor axis R1 and the major axis R2 of the fuel cell (R
2 is a graph showing the relationship between 2 / R1) and volume.

FIG. 7: Ratio (R of short diameter R1 and long diameter R2 of fuel cell)
2 is a graph showing the relationship between 2 / R1) and the number of cells.

FIG. 8 is a cross-sectional view showing a conventional cell stack in which a plurality of cylindrical fuel battery cells having interconnectors are connected.

FIG. 9 is a cross-sectional view showing a conventional cell stack in which a plurality of fuel cells without interconnectors are connected in parallel.

FIG. 10 is a cross-sectional view showing a conventional cell stack in which a plurality of flat fuel cell units having interconnectors are connected in series.

[Explanation of symbols]

34, 43, 49 ... Fuel cell 34a, 43a, 49a ... Flat parts of cells 34b, 43b, 49b ... Arc-shaped portions of cells 35, 44, 51 ... Fuel side electrode (inner electrode) 37, 46, 53 ... Solid electrolyte 39, 47, 55 ... Oxygen side electrode (outer side electrode) 41, 45, 57 ... Gas passage hole 61 ... Inner long conductive member 63 ... Connection conductive member R1 ... Short diameter R2 ... long diameter

Claims (9)

[Claims] 1. A flat inner electrode is provided with an annular solid electrolyte surrounding the inner electrode, and an outer surface of the solid electrolyte is provided with an annular outer electrode surrounding the solid electrolyte. A fuel battery cell characterized by the above. 2. The fuel cell according to claim 1, wherein the fuel cell has a flat shape composed of a pair of flat portions formed substantially in parallel with each other and an arc-shaped portion connecting end portions of the flat portions. cell. 3. The ratio R2 / R1 of the short diameter R1 and the long diameter R2 is 2.
It is above, The fuel cell of Claim 1 or 2 characterized by the above-mentioned. 4. The fuel cell according to claim 1, wherein the minor axis R1 is 10 mm or less. 5. The fuel cell according to claim 1, wherein at least one gas passage hole is formed in the axial direction in the inner electrode. 6. The fuel cell according to claim 5, wherein a conductive member that is electrically connected to the inner electrode is provided in the gas passage hole of the inner electrode. 7. An elongated conductive member is inserted into the gas passage hole of the inner electrode, and the elongated conductive member and the inner electrode are provided between the elongated conductive member and the inner surface of the inner electrode. 7. The fuel battery cell according to claim 5, further comprising a conductive member for connection for electrically connecting the fuel cell and the fuel cell. 8. A cell stack comprising a plurality of the fuel cells according to any one of claims 1 to 7 assembled together. 9. A fuel cell comprising a plurality of fuel battery cells according to claim 1 housed in a housing container.