JP3914990B2 - Cylindrical fuel cell - Google Patents

Description

The present invention relates to a cylindrical fuel cell, and in particular, a cylindrical series connection type (horizontal stripe cylindrical type) high-temperature solid electrolyte fuel cell (SOFC) using yttria-stabilized zirconia (YSZ) as an electrolyte.
oxide fuel cell).

The high-temperature solid electrolyte fuel cell (SOFC) is capable of power generation processes at high temperatures, so it can be used for several hundred kW class distributed power sources, as well as several hundred MW class large-capacity, high-efficiency composites combined with gas turbines and steam turbines. It is said that it is possible to realize a type of base load power plant. The power generation method using SOFC has high energy conversion efficiency to electric energy, can minimize the emission of air pollutants accompanying power generation, and has a variety of fuels such as coal gas and city gas due to the hydrogen purification function through internal reforming. It is also possible to respond to For these reasons, solid electrolyte fuel cells are highly expected as high-temperature operation fuel cells following phosphoric acid fuel cells (PAFCs) and molten carbonate fuel cells (MCFCs). Research and development is progressing.
Solid electrolyte fuel cells are roughly classified into a flat plate type and a cylindrical type. The cylindrical type is excellent in strength and relatively easy to separate gases. The cylindrical type is further classified into a vertical stripe type (Westinghouse type: high current type) and a horizontal stripe type (series connection type: high voltage type), but the present invention relates to the latter.

  FIG. 11 is a front view showing the upper half of a conventional horizontal stripe cylindrical solid electrolyte fuel cell in a cross-sectional view. As shown in FIG. 11, a dense ceramic film 51 is formed on the circumference of the porous ceramic base tube 50 to form an airtight part (non-power generation part) and a gas permeable part (power generation part). Thereafter, when the fuel electrode 52, the solid electrolyte membrane 53, the interconnector 54, the terminal lead 55 for extracting current, the dense ceramic membrane 56, and the air electrode 57 are sequentially formed, a fuel cell stack is completed. A lead wire 58 for current extraction and a ceramic end cap 59 for gas supply / exhaust are attached to both ends to complete the manufacturing process of the horizontal stripe cylindrical SOFC 200. As described above, although there are some differences in materials, the horizontal-striped cylindrical SOFC connects unit cells of a three-layer structure of fuel electrode-solid electrolyte-air electrode formed on a base tube in series via an interconnector. The configuration is as follows.

Here, the operation of the solid electrolyte fuel cell will be briefly described. A solid electrolyte fuel cell basically has a structure in which a solid electrolyte is sandwiched between electrode plates having good gas permeability. The solid electrolyte is a complex oxide which maintains a fluorite-type cubic crystal structure from room temperature to high temperature and is chemically stable. For example, (Y ₂ O ₃ ) _0.08 (ZrO ₂ ) _0.92 Yttria stabilized zirconia (YSZ) having the following composition is used. Yttria-stabilized zirconia has trivalent yttrium oxide in solid solution in tetravalent zirconium oxide, which causes oxide ion vacancies in the crystal. Move freely. When gas permeable electrodes are attached to both surfaces and an oxygen concentration difference is given to both surfaces, oxygen becomes O ²⁻ from the high concentration side (cathode, generally called an air electrode) and enters YSZ. Carries electrons by moving to the side (anode, commonly called fuel electrode). The O ²⁻ ions that have reached the anode react with the fuel to emit electrons, and the emitted electrons flow through an external circuit to work on the load.

In solid electrolyte fuel cells (SOFC), operating at high temperatures (for example, 800-1000 ° C) can make the most of its advantages, so how to keep thermal stress low is a critical issue. Therefore, it is desirable that all the components of the SOFC are configured by combining materials having a coefficient of thermal expansion. Therefore, oxide conductive materials such as lanthanum chromite oxides (LaCrO ₃ : those containing Mg, Ca and Ti are commonly used for adjusting the thermal expansion coefficient) are used as SOFC interconnector materials. (See, for example, Patent Documents 1 and 2). However, vertical stripes type: In (Westinghouse type high current type) for conductive path of the interconnect portion is short (originally, since a structure in which thought devised to shorten the conductive paths) and particular problem in LaCrO ₃ system material However, in the horizontal stripe type (series connection type: high voltage type), since the conductive path is long due to its structure, the use of an oxide-based material having poor conductivity causes a problem that the internal resistance of the cell becomes very high. Thus, it has been proposed to form an interconnector using a cermet made of an alloy material such as NiAl or NiCr having higher conductivity (see, for example, Patent Documents 3 and 4).
JP-A 52-21743 JP 2002-145658 A JP-A-8-162139 JP-A-8-222246

The interconnector is required to ensure hermeticity (gas tightness) and high conductivity. Conductive materials are also used for fuel electrodes and air electrodes, but these are porous membranes, so they are relatively unaffected by thermal stress, but interconnectors are made of dense membranes to ensure airtightness. As a result, a large internal stress is generated here. In particular, in the case of a horizontal stripe cylindrical type, the thickness of the interconnector becomes thick. Therefore, when using an alloy-based material, even if it is made cermet, the difference in thermal expansion coefficient from the solid electrolyte is large, and the interconnector part is repeatedly operated and stopped. It is easy for deterioration to progress. That is, peeling and cracking are likely to occur here. On the other hand, even if the interconnector is made of an alloy-based material, the interconnector is used as a cermet, so that the resistance value at the cell connection portion increases and it is difficult to ensure high conversion efficiency.
The present invention has been made to solve the above-mentioned problems, and its purpose is first to be able to suppress the internal stress generated in the interconnector portion, and secondly, The resistance at the interconnector portion can be kept low, thereby providing a high-temperature solid electrolyte fuel cell with high reliability, long life and high conversion efficiency, in which the occurrence of peeling and cracking is suppressed. Is something to try to do.

To achieve the above object, according to the present invention, first porous interconnector film which cells are stacked in the annular sequentially from a lower layer, a first electrode, a solid electrolyte film, a second electrode, a second porous interconnector The first porous interconnector membrane and the second porous interconnector membrane between adjacent cells are extended to the upper and lower surfaces of the intermediate interconnector membrane and connected by the intermediate interconnector membrane. The cylindrical fuel cell is characterized in that the intermediate interconnector membrane has at least one dense conductive film.
Preferably, the intermediate interconnector film is composed of a single dense conductive film or a porous conductive film and an upper dense conductive film and a lower dense conductive film sandwiching the porous from above and below. Preferably, the intermediate interconnector film is formed of any one of conductive oxide, NiCrAlY, SUS (stainless steel), inconel ( registered trademark ), or incoloy ( registered trademark ).
Preferably, the first and second porous interconnector films are formed of a material mainly composed of NiCrAlY, SUS (stainless steel), inconel ( registered trademark ), and incoloy ( registered trademark ). Yes.

According to the present invention, the interconnector structure includes a first porous interconnector membrane extending from the fuel electrode, a second porous interconnector membrane extending from the air electrode, and the first and second porous interconnectors. And an intermediate interconnector film sandwiched between the films. According to this structure, since the electrical conduction of the intermediate interconnector film is in the vertical direction, the film can be thinned within a range in which airtightness can be secured (about 20 to 300 μm). If the film thickness can be reduced, the internal stress generated can be kept low even when an alloy material having a difference in thermal expansion coefficient from that of the electrolyte is used. In addition, since the intermediate interconnector film is thinned, the electric resistance of the cell connection portion can be reduced. Furthermore, since the intermediate interconnector film is made thinner, it is possible to use an oxide-based conductive material such as LaCrO ₃ . That is, the resistance value of the cell connection portion can be kept low even if an oxide-based conductive material is used for the intermediate interconnector film.

  Further, according to the interconnector structure of the present invention, the peripheral portion of the intermediate interconnector membrane (that is, the region excluding the connecting portion with the second porous interconnector membrane) can be pressed by the electrolyte membrane. When the intermediate interconnector film is made of an alloy material such as NiCrAlY, the intermediate interconnector film made of a material having a large thermal expansion coefficient is pressed by an oxide having a small thermal expansion coefficient, and the interconnector film can be peeled off. The sex can be made lower.

Furthermore, according to the present invention, the intermediate interconnector film inserted between the first and second porous interconnector films can have a multilayer structure such as a dense film, a porous film, and a dense film. According to this structure, the buffer film is inserted between the dense films, and further, the stress is dispersed by dividing the dense film, so that a more durable interconnector can be realized. Further, since the intermediate interconnector film is divided, the function imposed on the interconnector film can be dispersed in each film, and the range of material selection is widened. That is, for example, the fuel-side dense film can be formed of a material having high reduction resistance, and the air-side dense film can be formed of a material having high oxidation resistance. For example, the dense film on both the fuel side and the air side can be formed of an alloy such as NiCrAlY to reduce the resistance value of the interconnector part. However, the dense film on the fuel side is formed of NiCrAlY and the fuel is reduced. The oxidation resistance can be further enhanced by securing the reduction resistance on the side and forming a dense film on the air side with LaCrO ₃ .

Next, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is a cross-sectional view schematically showing the structure of the cell connection portion according to the first embodiment of the present invention. As shown in FIG. 1, a porous metal IC (interconnector) film 2 is formed on a substrate tube 1, and a fuel electrode 3 and a dense metal IC film 4 are formed thereon. A solid electrolyte film 5 is formed on the fuel electrode 3 and the dense metal IC film 4 so as to cover the entire surface of the fuel electrode 3 and cover the periphery of the dense metal IC film 4. Further, an air electrode 6 is formed on the solid electrolyte membrane 5, and a porous metal IC film 7 is formed thereon so as to cover the air electrode and to cover the exposed portion of the dense metal IC film 4. Further, a peeling prevention film 8 is formed at the cut portion of the porous metal IC film 7 so as to cover the dense metal IC film 4.

A ceramic substrate tube can be used as the substrate tube 1. That is, a calcia-stabilized zirconia (CSZ) tube or an alumina tube can be used. Alternatively, a metal film-based substrate tube proposed by the present inventor in Japanese Patent Application No. 2003-303830 may be used. For example, NiCrAlY or the like is sprayed on a cylindrical Al temporary substrate to form an alloy film, and alumina or the like is sprayed thereon to form a ceramic film, and then the Al temporary substrate is etched away. Is. When operating at a high temperature of about 800 ° C. or higher, it is desirable to form the alloy film with NiCrAlY. However, in recent years, SOFC has a tendency to lower the temperature, and power generation at a lower temperature such as 600 ° C. to 800 ° C. For example, an alloy base tube can be formed using other Ni—Cr alloys such as SUS (stainless steel), inconel ( registered trademark ), and incoloy ( registered trademark ).

The porous metal IC film 2 can be formed by spraying NiCrAlY by, for example, flame spraying. The fuel electrode 3 can be formed, for example, by spraying NiO, for example, by plasma spraying. The dense metal IC film 4 can be formed by spraying NiCrAlY by, for example, flame spraying. The solid electrolyte membrane 5 can be formed by spraying YSZ, for example, by plasma spraying. The air electrode 6 can be formed by spraying, for example, LaMnO ₃ by flame spraying, for example. LaMnO ₃ may be added with oxides such as YSZ, ZrO ₂ , and Al ₂ O ₃ . In addition to or without including them, metals such as Mg, Ca, and Sr may be added. The porous metal IC film 7 can be formed by spraying NiCrAlY by, for example, flame spraying. The peeling prevention film 8 can be formed by spraying alumina, for example, by plasma spraying.

The porous metal IC films 2 and 7 and the dense metal IC film 4 are preferably formed of NiCrAlY if the SOFC is operated at a high temperature of about 800 ° C. or higher, but power generation at a temperature lower than that is preferable. If it aims, it can also form using other Ni-Cr type alloys, such as SUS (stainless steel), inconel ( registered trademark ), and incoloy ( registered trademark ).
An oxide such as alumina, YSZ, ZrO ₂ , or LaCrO ₃ can be added to the porous metal IC films 2 and 7. This facilitates the formation of a porous film during film formation.
It is desirable to keep the dense metal IC film 4 as thin as possible within a range in which airtightness (gas tightness) can be secured in order to keep the resistance value between cells low. From this viewpoint, the film thickness is selected from 20 μm to 300 μm. By reducing the thickness of the dense metal IC film 4, it is possible to simultaneously achieve the two effects of reducing the resistance value between cells and reducing the internal stress. Further, it is desirable that the dense metal IC film 4 is made as small as possible within the allowable range of the inter-cell connection resistance. By miniaturizing the dense metal IC film 4, the internal stress is further reduced, and the possibility of occurrence of cracks and peeling is further reduced. Further, since the intermediate IC film connecting the porous metal IC films 2-7 is thinned in this way, a dense conductive oxide IC film is formed using LaCrO ₃ or the like instead of the dense metal IC film 4. It becomes possible to form. Thus, by using a material having a thermal expansion coefficient close to that of the solid electrolyte for the intermediate IC film, it is possible to suppress an increase in thermal stress while suppressing an increase in resistance value between cells.

FIG. 2A is a perspective view showing a state in which up to the solid electrolyte membrane 5 is formed on the substrate tube, and FIG. 1 is a cross-sectional view taken along the line AA in FIG. . As shown in FIG. 2A, the dense metal IC film 4 is formed in a ring shape on the circumference, and both end portions of the dense metal IC film 4 are covered with the solid electrolyte film 5. That is, both end portions of the dense metal IC film 4 are pressed by the solid electrolyte film 5.
The dense metal IC film 4 is not continuously formed on the circumference, but is formed in a circular or strip shape as shown in FIGS. May be covered. A cross-sectional view taken along line BB in FIGS. 2B and 2C when the dense metal IC film 4 and the solid electrolyte film 5 are formed in this way is shown in FIG. A cross-sectional view taken along line AA in FIGS. 2B and 2C is as shown in FIG. Thus, the thermal stress can be kept very low by forming the dense metal IC film 4 in a small area and non-continuously. Alternatively, the dense metal IC film 4 may be formed in a ring shape (continuously), and a circular or strip-shaped window may be formed in the solid electrolyte film 5. A cross-sectional view taken along line BB in FIGS. 2B and 2C when the dense metal IC film 4 and the solid electrolyte film 5 are formed in this way is shown in FIG.
In the above description, the dense metal IC film 4 is formed directly on the porous metal IC film 2 by a thermal spraying method or the like. Instead of this method, the C-shaped IC shown in FIG. After forming the dense metal foil 4A for use in advance and forming the fuel electrode 3 on the porous metal IC film 2, the dense metal foil 4A for IC is fitted on the porous metal IC film 2 and then solidified from there. You may make it hold down with an electrolyte sprayed film.

  An exfoliation preventing film 8 is formed on the dense metal IC film 4 so as to cover the dense metal IC film 4. The peeling prevention film 8 is formed of an insulating oxide such as a dense alumina film, and its thermal expansion coefficient is smaller than that of the dense metal IC film. Therefore, the dense metal IC film 4 is pressed from above by the peeling prevention film 8 at a high temperature, and peeling of the dense metal IC film 4 is prevented. Even if the peeling prevention film 8 is formed of a porous alumina film, the same effect can be obtained.

FIG. 3A is a perspective view showing a state of the cell portion after the peeling prevention film 8 is formed. As shown in FIG. 3A, the peeling prevention film 8 is formed in a ring shape.
As shown in FIG. 3B, the peeling prevention film 8 may be formed so as to cover the entire surface of the solid electrolyte film 5 and the porous metal IC film 7. In this case, the peeling prevention film 8 is formed of a porous oxide film such as a porous alumina film. Alternatively, as shown in FIG. 3C, an anti-peeling film 8 having a ring-shaped slit may be formed. Further, as shown in FIG. 3D, a round hole may be provided at an appropriate location of the peeling prevention film 8. When formed as shown in FIGS. 3C and 3D, the peeling prevention film 8 is preferably formed of a porous film.
The peeling prevention film 8 is formed so as to cover at least the exposed part of the connection part of different kinds of films. And it is preferable to set it as a porous film at least on an electric power generation part.

[Second Embodiment]
FIG. 4 is a cross-sectional view showing a state of the cell connection portion according to the second embodiment of the present invention. In FIG. 4, the same reference numerals are given to the same parts as those of the first embodiment shown in FIG. In the present embodiment, the intermediate IC film disposed between the porous metal IC films 2-7 has a three-layer structure of the dense metal IC film 4a, the intermediate porous metal IC film 4b, and the dense metal IC film 4c. The Thus, the internal stress generated by dividing the dense metal IC film into two layers and inserting the porous metal IC film 4b serving as a buffer layer between them can be suppressed to a lower level.
All layers of the three-layer structure intermediate IC film may be formed of a conductive oxide such as LaCrO ₃ . Alternatively, only the upper two layers or the upper one layer may be made of a conductive oxide. In the case of forming a lower dense film with NiCrAlY and an upper dense film with LaCrO ₃ , the fuel electrode side can be a highly reducing material and the air electrode side can be a highly oxidizing material. A more durable interconnector can be realized.
When the uppermost layer of the intermediate IC film is formed of a heat resistant alloy such as NiCrAlY, it may be formed by the dense metal foil 4A for IC shown in FIG. 2 (d).
The dense metal IC films 4a and 4c are desirably kept as thin as possible within a range in which airtightness can be secured in order to keep the resistance value between cells low. From this viewpoint, the film thickness is selected from 10 μm to 200 μm. Further, the size (area) of the intermediate IC film (4a to 4c) is formed as small as possible within the allowable range of the inter-cell connection resistance.

[Third Embodiment]
FIGS. 5A and 5B are cross-sectional views showing the state of the cell connection portion according to the third embodiment of the present invention. In FIG. 5, the same reference numerals are concealed in the same parts as the parts of the first and second embodiments shown in FIGS. 1 and 4, and thus the overlapping description is omitted as appropriate.
The difference of the present embodiment from the first and second embodiments is that an auxiliary constraining film 9 is formed on the solid electrolyte film 5 so as to cover the periphery of the intermediate IC film (4; 4a to 4c). It is formed. The auxiliary constraining film 9 is formed of, for example, a porous alumina film, and is formed of a material having a smaller thermal expansion coefficient than an alloy such as an oxide. According to this structure, the intermediate IC film is pressed from above by the auxiliary constraining film 9 in addition to the solid electrolyte film 5, and even if a high temperature / normal temperature cycle is applied due to repeated operation and suspension. An interconnector structure that does not easily peel off can be realized.

FIG. 6A is a perspective view showing a state at the stage where the film formation process of the auxiliary restraint film 9 is completed in the process of manufacturing the SOFC of the present embodiment. As shown in the figure, in the present embodiment, the dense metal IC film 4 (4c) and the auxiliary restraining film 9 are formed in a ring shape.
As shown in FIGS. 6B and 6C, the auxiliary restraint film 9 is formed as one continuous film, and a circular or strip-like window for interconnector connection is opened at an appropriate place. May be. When formed in the state shown in FIGS. 6B and 6C, the dense metal IC film 4 (4c) may be formed continuously in a ring shape, but discontinuously formed in a circular shape or a strip shape. May be.

FIG. 7 is a cross-sectional view of the first embodiment of the present invention. In FIG. 7, the drawings that should be arranged side by side are described in two upper and lower stages. Originally, it should be arranged so that the wavy line in the upper diagram and the wavy line in the lower diagram are opposed to each other. The base tube 1 is formed of a 350 μm thick porous alloy film 1 a made of a NiCrAlY sprayed film and a 250 μm thick porous ceramic film made of an alumina sprayed film. The outer diameter of the base tube 1 is 20 mmφ and the length is 200 mm.
A terminal 10 comprising a terminal porous film 10a and a terminal dense film 10b is formed on both ends of the base tube 1 by thermal spraying of NiCrAlY, and subsequently a porous metal IC film 2 is formed by thermal spraying of NiCrAlY. A dense lead film 11 and a dense metal IC film 4 which are connection portions between the cell and the terminal 10 were formed by thermal spraying. Next, the fuel electrode 3 was formed by spraying NiO, and then the solid electrolyte membrane 5 was formed by spraying YSZ. Further, an air electrode 6 was formed by spraying LaMnO _{3, and} a porous metal IC film 7 was formed by spraying NiCrAlY so as to cover it. Thereafter, a protective film 12 made of an alumina dense film was formed by thermal spraying, and finally, a porous peeling prevention film 8 was formed by thermal spraying of alumina to produce a horizontal stripe cylindrical SOFC 100 consisting of 3 cells.

FIG. 9 is a graph showing the SOFC no-load test results obtained in Example 1. The horizontal axis is the elapsed time after the temperature rose to 915 ° C. The temperature was kept constant at 915 ° C. As can be seen from the figure, the voltage increases slightly over time. This is presumed to be a result of an increase in gas tightness (air tightness) of the dense metal IC film 4 over time. The voltage per unit cell was as high as about 1.047V after 990 hours, and an excellent SOFC with no gas leakage was realized.
FIG. 10 is a graph showing the SOFC load test results obtained in Example 1. The temperature is constant at 915 ° C.
Conventionally, high-temperature solid fuel cells have been formed mainly from oxides (ceramics) as can be seen from the name of SOFC, but this embodiment is formed mainly using alloys that are cheaper materials than ceramics. The conventional high-temperature solid fuel cell is a ceramic type, whereas the one according to the present invention can be called an alloy-type high-temperature solid fuel cell.

FIG. 8 is a cross-sectional view of Embodiment 2 of the present invention. In FIG. 8, the drawings that should be arranged side by side are described in two upper and lower stages. Originally, it should be arranged so that the wavy line in the upper diagram and the wavy line in the lower diagram are opposed to each other. The base tube 1 was a ceramic tube having an outer diameter of 20 mmφ and a length of 200 mm. First, the porous metal IC film 2 was formed by spraying NiCrAlY, and the dense metal IC film 4 and the terminal lead dense film 13a which becomes a part of the terminal lead 13 were also formed by spraying NiCrAlY. Next, the fuel electrode 4 was formed by spraying NiO, and then the solid electrolyte membrane 5 was formed by spraying YSZ. Further, the air electrode 6 is formed by spraying LaMnO _3, the porous metal IC film 7 is formed by spraying NiCrAlY so as to cover the air electrode 6, and the terminal which becomes a part of the terminal lead 13 at the end of the base tube 1 A lead porous film 13b was formed. Thereafter, a protective film 12 made of an alumina dense film was formed by thermal spraying, and finally, a porous peeling prevention film 8 was formed by thermal spraying of alumina to produce a horizontal stripe cylindrical SOFC 100 consisting of 3 cells.

The principal part sectional drawing of the 1st Embodiment of this invention. The perspective view and sectional drawing for demonstrating 1st Embodiment. The perspective view for demonstrating 1st Embodiment. Sectional drawing of the principal part of the 2nd Embodiment of this invention. Sectional drawing of the principal part of the 3rd Embodiment of this invention. The perspective view for demonstrating 3rd Embodiment. Sectional drawing of Example 1 of this invention. Sectional drawing of Example 2 of this invention. The graph which shows the result of the no-load test of Example 1 of this invention. The graph which shows the result of the load test of Example 1 of this invention. The front view which shows the upper half of a prior art example with sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base tube 1a Porous alloy film 1b Porous ceramic film 2, 7 Porous metal IC film 3 Fuel electrode 4, 4a, 4c Dense metal IC film 4A Dense metal foil for IC 4b Intermediate porous metal IC film 5 Solid electrolyte film 6 Air electrode 9 Auxiliary restraint membrane 10 Terminal 10a Terminal porous membrane 10b Terminal dense membrane 11 Lead dense membrane 12 Protective membrane 13 Terminal lead 13a Terminal lead dense membrane 13b Terminal lead porous membrane 50 Porous ceramic substrate tube 51, 56 Dense ceramic Membrane 52 Fuel Electrode 53 Solid Electrolyte Membrane 54 Interconnector 55 Terminal Lead 57 Air Electrode 58 Lead Wire 59 Ceramic End Cap 100, 200 Horizontally Striped Cylindrical SOFC

Claims (15)

The first porous interconnector film which cells are stacked in the annular sequentially from a lower layer, a first electrode, a solid electrolyte film, a second electrode, has a second porous interconnector film, the between adjacent cells 1 A cylindrical fuel cell in which a porous interconnector membrane and a second porous interconnector membrane are extended to the upper and lower surfaces of the intermediate interconnector membrane and connected by the intermediate interconnector membrane, wherein the intermediate interconnector A cylindrical fuel cell, wherein the membrane has at least one dense conductive film. 2. The intermediate interconnector film is constituted by a single dense conductive film or a porous conductive film and an upper dense conductive film and a lower dense conductive film sandwiching the porous from above and below. The cylindrical fuel cell as described. To claim 1 or 2, wherein the first and second porous interconnector film is characterized in that it is formed of a material mainly composed of heat resistance and high oxidation resistance heat and oxidation resistant alloy than Fe The cylindrical fuel cell as described. The cylindrical fuel cell according to claim 1 or 2, wherein the first and second porous interconnector films are made of a material mainly composed of NiCrAlY. 5. The oxide selected from alumina, zirconia, LaCrO ₃ , and YSZ is added to the first and second porous interconnector films. 6. Cylindrical fuel cell. The intermediate interconnector film, cylindrical fuel cell according to any of claims 1 5, characterized in that it is formed of a conductive oxide or NiCrAlY mainly composed of LaCrO _3. 3. The solid electrolyte membrane covers the single dense conductive film or the upper dense conductive film, exposing a connection portion with the second porous interconnector film. The cylindrical fuel cell as described.
The auxiliary constraining film made of a material having a smaller coefficient of thermal expansion than the first and second porous interconnector films is connected to the second porous interconnector film of the single dense conductive film or the upper dense conductive film. 8. The cylindrical fuel cell according to claim 7 , wherein the solid electrolyte membrane above the single dense conductive film or the upper dense conductive film is annularly covered while exposing the substrate . The cylindrical fuel cell according to claim 8 , wherein the auxiliary constraining membrane is a porous alumina membrane. So as to cover at least the intermediate interconnector Makujo, formed on the second porous interconnector film, the peeling prevention film annular made material having a small thermal expansion coefficient than the first and second porous interconnector film cylindrical fuel cell according to any of claims 1 9, characterized in that it is. The cylindrical fuel cell according to claim 10 , wherein an opening is formed at an appropriate place in the peeling prevention film. Cylindrical fuel cell according to any of claims 10 to 11, characterized in that the peeling prevention film is made of alumina. The cell is a ceramic substrate tube, or according to any one of claims 1 to 12, characterized in that it is formed on the heat-resistant alloy film tube into the ceramic film is coated comprising an alloy-based substrate tube on Cylindrical fuel cell. The cylindrical fuel cell according to claim 13 , wherein the ceramic substrate tube is made of alumina or calcia stabilized zirconia (CSZ). 14. The cylindrical fuel cell according to claim 13 , wherein the heat resistant alloy membrane tube is made of NiCrAlY.