JP2531824B2 - Solid oxide fuel cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a solid oxide fuel cell.

(Prior Art) Recently, a fuel cell has attracted attention as a power generation device. This is a device that can directly convert the chemical energy of fuel into electrical energy. It is not restricted by the Carnot cycle, so it has essentially high energy conversion efficiency and can diversify the fuel (naphtha, natural gas). ,methanol,
It is a very promising technology that has low pollution and power generation efficiency is not affected by the equipment scale.

In particular, solid oxide fuel cells (hereinafter referred to as SOFC)
The electrode reaction to operate at a high temperature of 1000 ° C is extremely active, no expensive precious metal catalyst such as platinum is required, the polarization is small, and the output voltage is relatively high. Remarkably high compared to Further, since the structural material is composed entirely of solid, it is stable and has a long life.

The components of the SOFC element are generally composed of an air electrode, a solid electrolyte and a fuel electrode.

The flat plate type SOFC device is promising because it has a large effective battery area per unit volume. A large number of such flat-plate SOFC elements are arranged in parallel, each element is rigidly sealed to form a power generation chamber, and oxidizing gas and fuel gas are sent from one side of the power generation chamber and combustion exhaust gas is discharged from the other side. What is known is.

(Problems to be solved by the invention) However, the one in which each SOFC element is fixed and sealed rigidly is in a state where the SOFC elements are hermetically bound to each other in order to form an airtight power generation chamber, Due to the high temperature, large thermal strain stress is generated at the edge of the SOFC element.
Particularly, when the base portion of the SOFC element is rigidly supported by the partition wall provided between the air supply chamber and the exhaust gas combustion chamber, the pressing stress due to this is large, and cracks are easily generated in the fragile SOFC element.

An object of the present invention is to provide a solid oxide fuel cell that is excellent in reliability and durability by relaxing stress at the edge portion of the SOFC element and preventing the occurrence of cracks.

(Means for Solving the Problems) The present invention provides a solid oxide fuel cell having at least a solid electrolyte, an air electrode provided on one side of the solid electrolyte, and a fuel electrode provided on the other side. An element; a gas supply chamber for supplying a gas to a gas flow passage provided inside the solid oxide fuel cell device; and an exhaust gas combustion chamber for causing a combustion reaction of the exhaust gas discharged from the gas flow passage In the solid oxide fuel cell having, the outer periphery of the solid oxide fuel cell element is held by a porous material between the gas supply chamber and the exhaust gas combustion chamber, the surface of this porous material is the gas supply The present invention relates to a solid oxide fuel cell, wherein the surface is covered with an airtight material so as not to be substantially exposed to the chamber and the exhaust gas combustion chamber.

The present invention also provides a solid electrolyte type fuel cell element having at least a solid electrolyte, an air electrode provided on one side of the solid electrolyte, and a fuel electrode provided on the other side; Solid electrolyte fuel having a gas supply chamber for supplying gas to a gas flow passage provided inside the fuel cell element; and an exhaust gas combustion chamber for performing a combustion reaction of exhaust gas discharged from the gas flow passage In the battery, the outer periphery of the solid oxide fuel cell element between the gas supply chamber and the exhaust gas combustion chamber is held by a substantially gas-impermeable porous material, a solid electrolyte Type fuel cell.

(Embodiment) FIG. 1 is a cross-sectional view showing an example of SOFC (cross-section AA of FIG. 2), FIG. 2 is a cross-sectional view of the same SOFC cut in the lateral direction, and FIG.
FIG. 4 is a sectional view taken along the line BB in FIG. 2, and FIG. 4 is a sectional view showing an SOFC device in which SOFC elements are integrated.

In this SOFC element 11, as shown in FIGS. 1 to 3, the elongated flat plate-shaped air electrode body 3 is used as a support body, and the air electrode body 3 is used.
In FIG. 1, the airtight interconnector 12 is formed in a film shape on the lower surface, and the airtight solid electrolyte membrane 9 is formed on the upper surface and the side surface. Cover the surroundings. The interconnector 12 is formed under the air electrode body 3 up to the end of the SOFC element 11. Similarly, the airtight solid electrolyte 9 is also provided on the upper surface of the air electrode body 3 with the SOFC element 11
To the end of. The air electrode body 3 is the exhaust gas combustion chamber 7
This is because it is vulnerable to CO gas and reducing gas such as water vapor. The fuel electrode membrane 10 is provided over the upper surface and the side surface of the solid electrolyte membrane 9 so as not to contact the interconnector 12.

 The SOFC element 11 is held as follows.

That is, the airtight partition 24 is provided near the left end of the SOFC element 11 in FIGS. 1 and 2, and the end of the SOFC element 11 is inserted into the through hole 24a provided in the airtight partition 24. To do.
Then, the gap between the through hole 24a and the outer peripheral surface of the SOFC element 11 is filled with the porous material 23, and the
The outer periphery of the FC element 11 is softly held. In FIG. 1 and FIG. 2 of the airtight partition wall 24 and the porous material 23, the left side is the oxidizing gas supply chamber 21, and the right side is the exhaust gas combustion chamber 7.

Further, an airtight wall portion 25 is further provided on the oxidizing gas supply chamber side of the airtight partition wall 24, and the porous material 23 is formed by the airtight wall portion 25.
The surface of is covered so that this surface is not exposed to the oxidizing gas supply chamber 21 side. An edge portion of the airtight wall portion 25 near the outer periphery of the SOFC element 11 is a slant portion 25a having a sharp tip, and the tip of the slant portion 25a contacts the outer periphery of the SOFC element 11. Slope 2
5a makes contact so that the SOFC element 11 is not substantially fixed, and therefore the SOFC element 11 and the inclined portion 25 are locally contacted at this contact portion.
Allow a gap to form with a.

On the other hand, an airtight inclined projection 22 having a sharp tip is provided on the outer periphery of the SOFC element 11, the surface of the porous material 23 on the exhaust gas combustion chamber side is covered with the inclined projection 22, and the surface of the porous material 23 is Exposure to the exhaust gas combustion chamber 7 is prevented. Also,
Preferably, a porous partition wall 2 is provided to separate the exhaust gas combustion chamber 7 from the power generation chamber 8, and the SOFC element 11 is also softly supported by the partition wall 2.

As the porous material 23, for example, ceramic fiber felt, ceramic fiber board, refractory heat insulating brick, heat insulating castable, etc. are preferable. As a material of the airtight wall portion 25, for example, refractory cement such as alumina, mullite, zirconia, mortar, or the like is preferable. Inclined protrusion 22
May be provided by adhering, adhering, or adhering this inclined protrusion to the outer periphery of the SOFC element 11.
Alternatively, the outer circumference of the element 11 may be formed to be thick, and then the inclined protrusion may be cut out by grinding.

The airtight wall portion 25 and the inclined protruding portion 25a can be formed integrally with the airtight partition wall 24 and made of a heat resistant material such as alumina, mullite, or zirconia. Further, the airtight wall portion 25 and the inclined protruding portion 25a may be formed of refractory cement on the surfaces of the airtight partition wall 24 and the porous material 23.

The flat air electrode body 3 is composed of doped or undoped LaMnO ₃ , CaMnO ₃ , LaNiO ₃ , LaCo.
La that can be made of O ₃ , LaCrO ₃ etc. and has strontium added
MnO ₃ is preferred. The airtight solid electrolyte membrane 9 can generally be manufactured from yttria-stabilized zirconia or the like. Fuel electrode membrane
Generally, 10 is preferably nickel-zirconia cermet or cobalt-zirconia cermet.

A plurality of rows of oxidizing gas transport paths 4A and 4B are provided inside the flat air electrode body 3, and an oxidizing gas supply port 16 and a closed portion 5 are alternately provided facing the oxidizing gas supply chamber 21. . SOFC
During the operation of, the oxidizing gas is sent from the oxidizing gas introduction hole 16 into the oxidizing gas transport path 4A as shown by the arrow E, reaches the end of the SOFC element on the power generation chamber side, and changes the direction here in the opposite direction. Then, it flows toward the oxidizing gas supply chamber 21 again in the oxidizing gas transport path 4B. Oxidizing gas supply chamber 21 of oxidizing gas transport path 4B
The closing portion 5 is provided at the side end as described above,
Moreover, the oxidant gas discharge port 6 is provided facing the exhaust gas combustion chamber 7. Therefore, the oxidizing gas is transferred to the oxidizing gas transport paths 4A, 4
While reciprocating in B, oxygen ions are supplied to the fuel electrode membrane 10 through the air electrode body 3 and the solid electrolyte membrane 9 to
The exhaust gas that has reacted with the fuel and contributes to power generation and has a reduced oxygen concentration is exhausted from the exhaust port 6 to the exhaust gas combustion chamber 7. On the other hand, it is designed such that the fuel gas flows to the exhaust gas combustion chamber 7 with a slight pressure difference between the power generation chamber 8 and the exhaust gas combustion chamber 7, and the reverse flow from the exhaust gas combustion chamber 7 to the power generation chamber 8 is generated. prevent. The fuel gas flows in the power generation chamber 8 as shown by an arrow F and is used for power generation. A mixed gas of steam, carbon dioxide gas and unreacted fuel gas generated by the reaction is generated in the partition wall 2 and the SOFC.
It flows into the exhaust gas combustion chamber 7 through the gap with the element, where it comes into contact with the exhaust oxidizing gas and burns, preheating the fresh oxidizing gas passing through the inside of the oxidizing gas transport path 4A.

Oxidizing gas produces oxygen ions at the interface between the air electrode body 3 and the solid electrolyte membrane 9, and these oxygen ions move through the solid electrolyte membrane 9 to the fuel electrode membrane 10 to react with the fuel gas and generate electrons. It is released to the fuel electrode film 10. Then, the Inco connector 12 connected to the air electrode which is the positive electrode,
A load is connected between the anode and the fuel electrode film 10 to extract electric power.

When a stack is formed as shown in FIG. 4, the airtight interconnector 12 is electrically connected to the fuel electrode film 10 of the lower SOFC element 11 via the nickel felt 14, and the SOFC element 11 Connect in series. Further, in FIG. 4, the fuel electrode films 10 of the SOFC elements 11 which are laterally adjacent to each other are electrically connected to each other through the nickel felt 13 so that the adjacent SO
The FC elements 11 are connected in parallel. In the example of FIG. 4, only two columns and two columns are shown for convenience, but the number of SOFC elements can be freely changed.

According to the solid electrode type fuel cell of the present embodiment, the following effects can be obtained.

(1) When holding the SOFC element 11 made of fragile ceramics, only one end of the base is fixedly held, and importantly, the outer periphery of the SOFC element 11 is held by the porous material 23.

Therefore, unlike the method of fixing the four circumferences of the SOFC element to the rigid like the conventional SOFC, structurally excessive strain stress is unlikely to occur, and since it is held by the porous material 23, the SOFC element 11 The strain stress can be further alleviated, and damage to this element can be effectively prevented.

(2) By supplying the oxidizing gas under pressure from the exhaust gas combustion chamber 7, the exhaust oxidizing gas is continuously discharged from the exhaust gas discharge port 6, and the fuel gas also passes through the gap between the partition wall 2 and the SOFC element 11. Since the structure is such that it is discharged into the exhaust gas combustion chamber 7, it is not necessary to seal and fix the four circumferences of the SOFC element.
It is sufficient to seal one end of the FC element 11.

Then, as described above, the airtight wall portion 25 and the inclined protruding portion
Since the surface of the porous material 23 is substantially covered with 22 and 22, the sealing between the oxidizing gas supply chamber 21 and the exhaust gas combustion chamber 7 is sufficiently performed. To describe this point in more detail, even if some fresh oxidizing gas enters the porous material 23 through the gap between the airtight wall portion 25 and the SOFC element 11, this oxidizing gas remains in the porous material 23. Once diffused, they move randomly in the porous material 23. Therefore, after the oxidizing gas moves in the porous material 23,
In addition, it is necessary to pass through the gap between the airtight partition wall 24 and the inclined protrusion portion 22, and this opportunity is very small. Further, due to the pressure loss in the porous material 23, the movement of the oxidizing gas to the exhaust gas combustion chamber 7 can be further reduced.

As described above, since it is not necessary to rigidly seal the SOFC element 11, strain stress due to this is less likely to occur, and the reliability as a structure is improved.

(3) Since the tip of the airtight wall portion 25 is the inclined portion 25a, even if the tip of the inclined portion 25a comes into contact with the outer periphery of the SOFC element 11, this contact area is extremely small, and therefore the pressing stress due to this contact is small. can do.

(4) Since the exhaust gas combustion chamber 7 is provided adjacent to the oxidizing gas supply chamber 21, for example, the oxidizing gas leaking from the oxidizing gas supply chamber 21 does not come into direct contact with fresh fuel gas, and the power generation chamber is already in use. After passing through No. 8, the residual fuel ratio becomes small and it comes into contact with the waste fuel gas containing a large amount of water vapor. Therefore, it is possible to prevent local rapid heat generation due to combustion at the end of the SOFC element 11,
It is possible to prevent cracking of the SOFC element due to thermal strain. Moreover, since excessive local heat generation is prevented, local deterioration of the SOFC element can be prevented, and the durability of the SOFC element is improved.

(5) Conventionally, since the fuel content is still large in the vicinity of the fuel gas introduction part, the electrochemical reaction is active and the temperature rises, and the temperature rise causes the reaction to become more active. On the other hand, at the other end, since the concentration of the fuel gas is considerably reduced, the reaction is inactive and the temperature is low, and the low temperature makes the reaction even more inactive. Moreover, the reacted fuel gas contains a considerable amount of CO ₂ , water vapor, etc.,
Since this adheres to the electrode surface and hinders the reaction, the temperature further decreases. This tendency becomes more pronounced as the size of the planar SOFC device increases.

On the other hand, in the present embodiment, the oxidizing gas supply ports 16 and the closed portions 5 are alternately provided, and the oxidizing gas once supplied from the oxidizing gas supply port 16 is reciprocated in the longitudinal direction of the SOFC element 11. The active part of the electrochemical reaction is not concentrated in only a part, but is relatively dispersed over the entire SOFC element. Therefore,
The temperature gradient of the entire SOFC element can be reduced, and thermal strain stress can be reduced, power generation can be made uniform, and power generation effect can be improved throughout the SOFC element and the SOFC element parallel connection stack.

(6) In each oxidizing gas transport path 4b, adjacent exhaust oxidizing gas outlets 6 are not provided on the same plane in the lateral direction of the SOFC element 1, but are provided obliquely and alternately with respect to the horizontal plane of the SOFC element 11. There is. Therefore, the outlets 6 that reduce the structural strength are not aligned in the horizontal direction on the same plane, which is advantageous in structural mechanics and can prevent the strength of the SOFC element 11 from being reduced due to bending stress.

(7) Not only the fuel electrode film 10 on the main surface side of the SOFC element 11,
The electrode area can be further increased because it is provided so as to expand to the side surface within the range where it does not contact the interconnector 12.

(8) In the power generation chamber 8 and the exhaust gas combustion chamber 7, since the outer peripheral surface of the air electrode body 3 is covered with the airtight interconnector 12 and the airtight solid electrolyte 9, the reducing gas and steam generated by the combustion are generated. It is possible to effectively prevent the air electrode body 3 from coming into contact with it and deteriorating it.

(9) Since the SOFC element has a box-type multi-channel structure, the structural strength of the element itself can be improved.

In the above example, the fuel electrode film 10 is provided so as to cover the main surface (upper side surface in the drawing) and the side surface of each element 11, but such a fuel electrode film is used for the main surface (upper side surface in the drawing) of each SOFC element 11. It is also possible to provide only on the side and not to extend to the side surface of the element. Then, at the time of electrical connection between the SOFC elements, nickel felt was brought into contact with the lower surface of the interconnector and the upper surface of the fuel electrode film, and a plurality of SOFC elements were vertically arranged in the same manner as shown in FIG. The SOFC elements are connected in series by arranging them to form a stack. Then, in order to equalize the distribution of the entire potential and the band composed of a plurality of stacks, SOFC elements that are laterally adjacent to each other are connected by the above-mentioned nickel felt of an integral body, and the stacks may be connected in parallel. Desirable but also laterally adjacent SOFCs
Do not connect the fuel electrode films of the elements directly with nickel felt.For example, configure multiple stacks with SOFC elements directly connected, and connect the fuel electrode films at the top of each stack with a common metal electrode. The current may be collected, and the interconnector at the lower end of each stack may be connected with a common metal electrode to collect the current.

In this way, if the fuel electrode membrane is not provided on the side surface of the SOFC element, only the insulating solid electrolyte membrane is exposed on this side surface, and therefore, for example, the fuel electrode membrane and the interconnector are electrically short-circuited. There is no danger of it becoming more practical.

FIG. 5 shows a stack in which a plurality of SOFC elements 11 are connected. FIG. 2 is a partial sectional view similar to FIG. 1. SOFC of this example
In the above, the configuration of each SOFC element 11 is the same as that of the SOFC in FIG.

Also in the SOFC of this embodiment, a unique structure is adopted as the seal and partition structure between the oxidizing gas chamber 21 and the exhaust gas combustion chamber 7.

That is, the airtight partition wall 24 shown in FIG. 1 is not adopted, but instead, the porous material 34 is filled in the gap between the adjacent SOFC elements 11, and the outer periphery of the end portion of each SOFC element 11 is filled with the porous material 34. Cover with SO
The FC element 11 was held. As a result, the SOFC elements 11 are flexibly supported by the porous material 11 in a vertically stacked state as shown in FIG.

Then, in order to prevent the leakage of the oxidizing gas from the oxidizing gas chamber 21 to the exhaust gas combustion chamber 7, the airtight chamber material is used for sealing. That is, each of the SOFC elements 11 is provided with an airtight inclined protrusion 32 or 33, and the inclined protrusions of the SOFC elements 11 vertically adjacent to each other are provided.
32 and 33 are brought into contact with each other or separated with a slight gap therebetween so that the surface of the porous material 34 is covered so as not to be substantially exposed to the exhaust gas combustion chamber side. Further, on the surface of the porous material 34 on the side of the oxidizing gas chamber, an airtight holding member 35 having a triangular cross section is provided, and an edge of the airtight holding member 35 is brought into contact with the outer peripheral surface of the SOFC element 11, or a slight amount. Porous material fixed with a gap
The surface of the oxidizing gas chamber side of 34 is covered with an airtight holding member 35 so as not to be substantially exposed. The airtight holding member 35 is preferably formed of, for example, refractory cement, mortar, or the like,
Alternatively, a small protrusion may be provided on the outer periphery of the end portion of the SOFC element 11, and the small protrusion may be used to fix the airtightness holding member 35 so as not to shift its position toward the outside of the stack.

The SOFC of this embodiment can also achieve the same effects as the SOFC of FIG. Moreover, since the structure in which the SOFC element 11 is held only by the porous material 34 without using the airtight partition wall 24 (FIG. 1), the structure is simpler and the spatial integration degree of the SOFC element 11 is improved. It is even easier to raise it.

Instead of disposing the airtight holding member 35, an inclined protrusion may be provided on the outer circumference of the SOFC element 11 to cover the surface of the porous material 34, or fire-resistant cement, mortar or the like may be thinly applied. The surface of the porous material 34 may be covered. Also,
Water glass, colloidal filter, or metal foil such as iron may be provided instead of the airtight holding member.

FIG. 6 is a cross-sectional view of another SOFC taken along the same cross-section as in FIG. The same functional members as those of the SOFC of FIG. 1 are designated by the same reference numerals, and the description thereof is omitted.

In the SOFC of this example, the surface of the porous material is not covered with the airtight material, and a substantially gas-impermeable porous material is used as the porous material 43. Specifically, such a porous material has substantially no gas permeability because most of the pores are closed pores and there are no or almost no open pores, and the open pores are not in communication with each other. It is a thing. As such a porous material, for example, a material in which glass beads or the like are fired in ceramics such as Aruna or silica to form closed pores is preferable.

According to the SOFC of the present embodiment, the SOFC element 11 is held in the lift by the substantially gas impermeable porous material 43, and at the same time, the seal between the oxidizing gas supply chamber 21 and the exhaust gas combustion chamber 7 is sufficient. Therefore, the same effect as the SOFC in FIG. 1 can be obtained. Moreover, since the holding structure is simpler, it is more preferable from the viewpoint of manufacturing.

As described above, although the embodiment in which the present invention is applied to the flat-plate SOFC element having the special structure has been described, for example, the holding structure of the cylindrical SOFC with both ends opened, the bag-shaped cylindrical SOFC with one end sealed The present invention can be applied to a holding structure, a general flat SOFC holding structure, and the like.

 The above-described embodiment can be variously modified as follows, for example.

The shape, size and structure of the porous material and the shape and structure of the airtight material covering the surface of the porous material can be variously changed.

As shown in FIG. 1 to FIG. 4, instead of extending the fuel electrode film 10 to the side surface of the SOFC element 11, the interconnector 12 is provided to the side surface of the SOFC element in a range not in contact with the fuel electrode film 10. You may extend inside. At this time, the fuel electrode membrane 10 may be retracted as necessary to avoid a short circuit with the interconnector 12. Also, the airtight interconnector 12
May be provided on the airtight solid electrolyte membrane 9, or the solid electrolyte membrane 9 may be set back so that they do not overlap, but the airtight solid electrolyte membrane 9 and the airtight interconnector
It is preferable that the surface of the air electrode body 3 is not exposed from between 12 and 12.

Although the number and sectional shape of the oxidizing gas transport paths may be variously changed, it is preferable that the oxidizing gas transport paths 4A and 4B are alternately provided from the viewpoint of thermal gradient as shown in FIG.

When forming the blocking portion 5, for example, a method is used in which a mold is made of an organic material, and an air electrode material is poured into the shape of the blocking portion 5 to burn and the organic material disappears. The blocking portion 5 is individually molded and fired to supply an oxidizing gas supply port. Various methods such as a method of adhering, fixing, adhering, fitting, etc. can be adopted.

In the above example, the air electrode body was provided with the oxidizing gas transport passage, and the solid electrolyte membrane and the fuel electrode membrane were sequentially formed on this, but conversely, the flat fuel electrode body was provided with the fuel gas transport passage, and on top of this. It is also possible to sequentially form the solid electrolyte membrane and the air electrode membrane, and to allow the oxidizing gas to flow into the power generation chamber.

When the partition wall 2 is made of an air-permeable porous material, the gas on the power generation chamber side can be made to flow into the exhaust gas combustion chamber side.

A porous air electrode film may be formed on the porous flat plate-shaped conductive electrode support, and a solid electrolyte may be further formed on the porous air electrode film to have the same structure as that described above. In Figure 1, each SOFC
Although the element 11 is supported horizontally, the entire power generation device may be vertical or may be tilted at a predetermined angle.

The planar shape of the planar SOFC element is not limited to a square or a rectangle, but may be a triangle, a hexagon, a circle, or the like.

Further, the plate-like form of the plate-like SOFC element may be a corrugated shape, a conical shape, a pyramid shape, a spherical shape or the like other than the flat shape.

(Effect of the Invention) According to the solid oxide fuel cell of the present invention, since the outer periphery of the solid oxide fuel cell element is held by the porous material between the gas supply chamber and the exhaust gas combustion chamber, the solid electrolyte Unlike the method of rigidly fixing the four circumferences of the fuel cell element, the strain stress that is structurally excessive is unlikely to occur, the strain stress can be relaxed, and damage to the solid oxide fuel cell element can be effectively prevented.

Moreover, the surface of the porous material is covered with the airtight material,
Since the surface of the porous material is not substantially exposed to the gas supply chamber and the exhaust gas combustion chamber, it is very difficult for fresh gas to leak from the gas supply chamber to the exhaust gas combustion chamber, and a sufficient seal is provided. It can be carried out. Therefore, since it is not necessary to rigidly seal the solid oxide fuel cell device, strain stress caused by this is less likely to occur, and the reliability of the structure is improved.

Further, according to the solid oxide fuel cell of the present invention,
Since the outer periphery of the solid oxide fuel cell device is held by the porous material between the gas supply chamber and the exhaust gas combustion chamber,
Unlike the method of fixing the four circumferences of the solid oxide fuel cell device to the rigid, it is difficult for structurally excessive strain stress to occur,
The strain stress can be relaxed, and damage to the solid oxide fuel cell device can be effectively prevented.

Moreover, since the porous material is substantially gas impermeable, it is very difficult for fresh gas to leak from the gas supply chamber to the exhaust gas combustion chamber, and sufficient sealing can be performed. Therefore, since it is not necessary to rigidly seal the solid oxide fuel cell device, strain stress caused by this is less likely to occur, and the reliability of the structure is improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing the holding state of the SOFC element (A in FIG. 2).
-A cross-section), Fig. 2 is a cross-sectional view of the SOFC of Fig. 1 cut laterally, Fig. 3 is a cross-sectional view taken along the line BB of Fig. 2, and Fig. 4 is a series of SOFC elements connected in series. Fig. 5 is a sectional view showing a state in which the SOFC element is held by another holding structure (cut in the same direction as in Fig. 1), and Fig. 6 is a sectional view showing another SOFC element. It is sectional drawing which shows a holding state. 2 ... (Porous) partition wall 3 ... Flat plate air electrode assembly 4A ... Oxidizing gas transport path (outgoing path) 4B ... Oxidizing gas transport path (return path) 5 ... Closure part 6 ... Exhaust oxidizing gas exhaust port 7 ...... Exhaust gas combustion chamber 8 …… Power generation chamber 9 …… Solid electrolyte membrane 10 …… Fuel electrode membrane 11 …… SOFC element 12 …… Airtight interconnector 13,14 …… Nickel felt 21 …… Oxidation gas chamber 22,32 , 33 …… Airtight slanted protrusion 23, 34 …… Porous material 24 …… Airtight partition 24a …… Through hole 25 …… Airtight wall 35 …… Airtight holding member 43 …… Substantially gas Impermeable porous material E ... flow of oxidizing gas F ... flow of fuel gas

Claims (2)

(57) [Claims] 1. A solid electrolyte fuel cell element comprising at least a solid electrolyte, an air electrode provided on one side of the solid electrolyte, and a fuel electrode provided on the other side; Solid electrolyte fuel cell having a gas supply chamber for supplying gas to a gas flow passage provided inside the cell element; and an exhaust gas combustion chamber for causing a combustion reaction of exhaust gas discharged from the gas flow passage In, the outer periphery of the solid oxide fuel cell element is held by a porous material between the gas supply chamber and the exhaust gas combustion chamber, the surface of the porous material in the gas supply chamber and the exhaust gas combustion chamber A solid oxide fuel cell, wherein the surface is covered with an airtight material so as not to be substantially exposed. 2. A solid electrolyte fuel cell element comprising at least a solid electrolyte, an air electrode provided on one side of the solid electrolyte, and a fuel electrode provided on the other side; Solid electrolyte fuel cell having a gas supply chamber for supplying gas to a gas flow passage provided inside the cell element; and an exhaust gas combustion chamber for causing a combustion reaction of exhaust gas discharged from the gas flow passage In the above, the outer periphery of the solid oxide fuel cell element between the gas supply chamber and the exhaust gas combustion chamber is held by a substantially gas impermeable porous material. Fuel cell.