JP2007179965A - Solid electrolyte fuel cell, and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolyte fuel cell having flexibility required when stacking it as a matter of course, and having little possibility of causing a fault such as a crack or the like in a join part of a unit cell and a support plate supporting it. <P>SOLUTION: This solid electrolyte fuel cell is equipped with the unit cell 2 formed by holding an electrolyte layer 5 between a pair of electrode layers 3, 4, and the cell support plate 6 supporting the unit cell 2. A highly rigid join part 11 joined to the unit cell 2, and an assembly 10 positioned around the join part 11 while having a stress relaxing part 12 having rigidity lower than that of the join part 11 are provided between the unit cell 12 and the support plate 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solid oxide fuel cell having a single cell in which a solid electrolyte layer is sandwiched between a pair of electrode layers, and a method for manufacturing the same.

  As a conventional solid electrolyte fuel cell, for example, a cell having a single cell formed by sequentially laminating an electrolyte layer and an air electrode layer on a fuel electrode layer, and a metal cell support plate that supports the single cell. In this solid oxide fuel cell, the electrolyte layer of the single cell and the cell support plate are joined.

Such a solid oxide fuel cell is required to be compact and lightweight for the convenience of stacking and stacking, and also to be flexible in order to mitigate thermal and mechanical shocks. A thin metal plate is used as the support plate.
JP 2004-220954 A

  However, in the above-described conventional solid oxide fuel cell, since a metal thin plate is used as the cell support plate, the cell support plate is deformed during assembly or when the battery is used. There is a problem that thermal and mechanical stress is applied to the joint part with the material, and as a result, there is a risk that a defect such as a crack may occur in the joint part. It has been a conventional problem to solve this problem It was.

  The present invention has been made paying attention to the above-described conventional problems, and of course has the flexibility required for stacking, as well as a single cell and a cell support plate that supports the cell. It is an object of the present invention to provide a solid oxide fuel cell and a method for manufacturing the same, which are unlikely to cause defects such as cracks at the joint.

  The present invention relates to a solid oxide fuel cell including a single cell formed by sandwiching an electrolyte layer between a pair of electrode layers, and a metal cell support plate that supports the single cell. In the meantime, it is characterized in that a joined body having a highly rigid joint part joined to a single cell and a stress relaxation part located around the joint part and having lower rigidity than the joint part is provided. Therefore, the configuration of the solid oxide fuel cell is used as a means for solving the above-described conventional problems.

  In the solid oxide fuel cell of the present invention, even if the metal cell support plate is deformed during assembly or when the battery is used, the low-rigidity stress relaxation portion of the joined body located between the single cell and the cell support plate However, since the deformation of the cell support plate is flexibly absorbed, thermal and mechanical stress is hardly transmitted to the joint portion between the single cell and the joined body, and for example, the joint portion between the single cell and the joined body. Even if a slight amount of thermal and mechanical stress is applied, since the joint portion of the joined body has high rigidity, it is possible to avoid the occurrence of defects such as cracks at the joint portion with the single cell.

  According to the present invention, since it is configured as described above, it is needless to say that the flexibility required for stacking can be maintained as in the conventional case, and the unit cell and the cell support plate that supports the cell are joined. This provides an excellent effect that a solid oxide fuel cell can be provided which has almost no possibility of occurrence of defects such as cracks in the portion.

  In the solid oxide fuel cell of the present invention, high rigidity that is bonded to a separator between a metal separator that contacts a single cell via a current collector and a metal separator support plate that supports the separator. And a joined body having a stress relieving portion which is positioned around the joint portion and has rigidity lower than that of the joint portion.

  In this case, even if the metal separator is deformed during assembly or when the battery is used, the low-rigidity stress relaxation portion of the joined body located between the separator and the separator support plate flexibly deforms the separator. Absorption causes avoidance of contact failure between the separator and the current collector and between the current collector and the electrode portion of the single cell.

  Further, in the solid oxide fuel cell of the present invention, the joint portion that is positioned around the stress relaxation portion of the joined body and is joined to the cell support plate or the separator support plate is a joint portion having higher rigidity than the stress relaxation portion. It is possible to adopt a configuration, and in this case, all of the joint portions located across the stress relaxation portion of the joined body may have a substantially identical cross-sectional shape.

  Adopting this configuration, for example, even if the metal cell support plate is deformed at the time of assembly or battery use, the low-rigidity stress relaxation part of the joined body flexibly absorbs the deformation of the cell support plate. The joined part of the joined body to the cell support plate is hardly subjected to thermal and mechanical stress, and even if a slight thermal and mechanical stress is applied to the joined part, the joined part of the joined body is increased. Since it is rigid, it is avoided that defects such as cracks occur in the joint portion with respect to the cell support plate.

  Furthermore, in the solid oxide fuel cell according to the present invention, it is possible to employ a configuration in which the joint portion and the stress relaxation portion of the joined body are formed of the same material, for example, ferritic stainless steel. In addition, the stress relaxation portion may be integrally formed, or the joint portion and the stress relaxation portion that are separate from each other may be joined by brazing or the like.

  Here, as a means for giving a difference in rigidity between the joint part and the stress relaxation part of the joined body, use a configuration in which the thickness of the stress relaxation part of the joined body is made thinner than that of the high-rigidity joint to lower the rigidity. Specifically, it is desirable that the stress relaxation portion of the joined body has a configuration in which the cross section has a groove shape, a saddle shape, or a waveform.

  Furthermore, in the solid oxide fuel cell of the present invention, the joint portion and the stress relaxation portion of the joined body may be formed of different materials. For example, the joint of the joined body can be made of ferritic stainless steel, and the stress relaxation part can be made of austenitic stainless steel.

  When manufacturing any of the solid oxide fuel cells described above, a joined body having a highly rigid joint portion and a stress relaxation portion having a rigidity lower than that of the joint portion between the single cell and the cell support plate. It is possible to employ a manufacturing method in which the single cell and the cell support plate are joined by arranging and joining the joint portion of the joined body to the single cell and joining the stress relaxation portion side to the cell support plate.

At this time, in consideration of matching the coefficient of thermal expansion for joining the joint portion of the joined body and the single cell, glass composed of barium oxide, silica, alumina and calcia (referred to as BSAC glass; Ba (52 wt%) _{) -SiO 2 (33wt%) -} Al 2 O 3 (3wt%) - it is desirable to use CaO (12wt%)).

  In the present invention, by stacking any of the solid oxide fuel cells described above, a stack structure of the solid oxide fuel cell can be formed. At this time, the metal structure of the solid oxide fuel cell is made of metal. Since the cell support plate and the separator have flexibility, thermal shock and mechanical shock during operation are alleviated.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example.

[Example 1]
FIG. 1 shows an embodiment of a solid oxide fuel cell according to the present invention. As shown in FIG. 1, this solid oxide fuel cell 1 has an electrolyte layer 5 between a pair of electrode layers 3 and 4. The single cell 2 formed by sandwiching it and a metal cell support plate 6 that supports the single cell 2 form a disk shape as a whole, and between the single cell 2 and the cell support plate 6 A high-rigidity joint 11 joined to the single cell 2 via the adhesive 14, a stress relaxation part 12 positioned around the joint 11 and having a lower rigidity than the joint 11, and the stress relaxation part Is provided with a joint 10 having a highly rigid joint 13 that is joined to the cell support plate 6, and at this time, joints 11 and 13 that are located across the stress relaxation part 12 of the joint 10. Have substantially the same cross-sectional square shape.

  In this embodiment, the unit cell 2 is a so-called fuel electrode support type cell, and has a Ni—YSZ cermet porous layer having a diameter of 80 mm and a thickness of 0.6 mm made of nickel and 8YSZ (8 mol% yttria stabilized zirconia). As the fuel electrode layer 3, 8YSZ having a thickness of 8 μm is formed as the electrolyte layer 5 on the entire upper surface of the fuel electrode layer 3, and the air electrode layer 4 is within a range of φ60 mm from the center on the upper surface of the electrolyte layer 5. A single cell 2 was formed by forming a lanthanum-strontium-manganese oxide film having a thickness of 15 μm.

  On the other hand, the cell support plate 6 was formed into a donut shape using a ferrite stainless steel (SUS430) having a thickness of 100 μm.

  As shown in FIG. 2, the joined body 10 positioned between the single cell 2 and the cell support plate 6 is a ferrite having a ring shape with an outer diameter of φ80 mm having a square cross section with a thickness of 0.4 mm and a width of 4 mm. Stress relaxation between a joint 11 made of a stainless steel (SUS430) and a joint 13 made of a ferritic stainless steel (SUS430) having a ring shape with an outer diameter of φ100 mm having a square cross section with a thickness of 0.4 mm and a width of 4 mm The part 12 is formed by joining with a ferritic stainless steel (SUS430) foil having a thickness of 50 μm, and the joints 11 and 13 are joined to the stress relaxation part 12 by brazing with nickel / silver brazing.

  In this case, the stress relaxation part 12 of the joined body 10 was molded so that the cross section thereof had a groove shape, and the depth of the groove was adjusted to about 0.2 mm.

  And while joining the electrolyte layer 5 of the single cell 2 and the junction part 11 of the conjugate | zygote 10 via the BSAC glass 14, the junction part 13 and the cell support plate 6 of the conjugate | zygote 10 are joined, and this Example The solid oxide fuel cell 1 was obtained.

  Next, the solid oxide fuel cells 1 thus obtained are sequentially stacked, that is, as shown in FIG. 3, the single cell 2 and the cell support plate 6 joined by the joined body 10 are formed into a flat plate separator 7. 4 and the current collector 8 shown in FIG. 4, and the cell support plate 6 and the separator 7 are joined and fixed to the stainless steel frame 9 through the BSAC glass 14 to form a 15-stage stack (3 stages in FIG. 3). A structure was obtained.

  Accordingly, air is supplied to the air electrode layer 4 side of the unit cell 2 of the solid oxide fuel cell 1 in the stack structure, and hydrogen is supplied to the fuel electrode layer 3 side of the unit cell 2 to increase the temperature from room temperature to 700 ° C. When the temperature was increased and decreased 30 times, not only the single cell 2 and the cell support plate 6 but also the joint portion between the single cell 2 and the joint portion 11 of the joined body 10 were cracked. There were no problems. As a matter of course, no gas leak occurred between the anode chamber and the cathode chamber.

  As a result, it has been demonstrated that the solid oxide fuel cell 1 and the stack structure formed by laminating the same in this example have excellent durability while maintaining the required flexibility as in the past. did it.

[Example 2]
FIG. 5 shows another embodiment of the solid oxide fuel cell of the present invention. As shown in FIG. 5, the solid oxide fuel cell 21 of this embodiment is the same as that of the previous embodiment. The battery 1 is different from the battery 1 in that a joined body 30 is formed of a ferritic stainless steel (SUS430) joined portion 31 having a ring shape with an outer diameter of φ80 mm having a square cross section with a thickness of 4 mm and a thickness of 4 mm. A ferritic stainless steel (SUS430) foil having a thickness of 50 μm as a stress relieving portion 32 is formed by joining a joint 33 made of ferritic stainless steel (SUS430) having an outer diameter of φ100 mm having a square cross section of 1.0 mm and a width of 4 mm. The other structure is the same as the previous embodiment.

  The stack structure formed by laminating the solid oxide fuel cells 21 in this example was operated in the range of room temperature to 700 ° C. as in the previous example. In addition to the single cell 2 and the cell support plate 6, defects such as cracks did not occur in the joint portion between the single cell 2 and the joint portion 31 of the joined body 30.

  Therefore, it can be demonstrated that the solid oxide fuel cell 21 and the stack structure formed by laminating the same in this embodiment also have excellent durability while maintaining the required flexibility as in the past. It was.

[Example 3]
FIG. 6 shows still another embodiment of the solid oxide fuel cell of the present invention. As shown in FIG. 6, the solid electrolyte fuel cell 41 of this embodiment is the same as the solid electrolyte type of the previous embodiment. The difference from the fuel cell 1 is that the stress relaxation portion 52 of the joined body 50 is formed so that the cross section thereof has a bowl shape, and other configurations are the same as those of the previous embodiment.

  When the stack structure formed by stacking the solid oxide fuel cells 41 in this example was operated in the range of room temperature to 700 ° C. as in the previous example, even if the temperature was raised and lowered 30 times, In addition to the single cell 2 and the cell support plate 6, defects such as cracks did not occur in the joint portion between the single cell 2 and the joint portion 51 of the joined body 50.

  Therefore, it can be demonstrated that the solid oxide fuel cell 41 and the stack structure formed by laminating the same in this embodiment also have excellent durability while maintaining the required flexibility as in the past. It was.

[Example 4]
FIG. 7 shows still another embodiment of the solid oxide fuel cell of the present invention. As shown in FIG. 7, the solid electrolyte fuel cell 61 of this embodiment is the same as the solid electrolyte type of the previous embodiment. The difference from the fuel cell 1 is that the stress relaxation portion 72 of the joined body 70 is shaped so that its cross section has a waveform, and other configurations are the same as in the previous embodiment.

  The stack structure formed by stacking the solid oxide fuel cells 61 in this example was operated in the range of room temperature to 700 ° C. as in the previous example. In addition to the single cell 2 and the cell support plate 6, defects such as cracks did not occur in the joint portion between the single cell 2 and the joint portion 71 of the joined body 70.

  Therefore, it can be proved that the solid oxide fuel cell 61 and the stack structure formed by laminating the same in this embodiment also have excellent durability while maintaining the required flexibility as in the past. It was.

[Example 5]
FIG. 8 shows a metal separator 87 of a solid oxide fuel cell 81 and a metal separator support plate 88 that supports the separator 87 in still another embodiment of the present invention. In this embodiment, a joined body 90 is also provided between the separator 87 and the separator support plate 88, and other configurations are the same as those of the first embodiment.

  In this example, the separator 87 and the separator support plate 88 are both made of ferrite stainless steel (SUS430) having a thickness of 100 μm.

  The joined body 90 positioned between the separator 87 and the separator support plate 88 is a joined part made of ferritic stainless steel (SUS430) having a ring shape with an outer diameter of φ80 mm having a square cross section with a thickness of 0.4 mm and a width of 4 mm. 91 and a ferrite-based stainless steel (SUS430) joint 93 having a ring shape with an outer diameter of φ100 mm having a square cross section with a thickness of 0.4 mm and a width of 4 mm is used as a stress-relieving portion 92 of a ferrite system having a thickness of 50 μm. It joined by stainless steel (SUS430) foil, and the joining parts 91 and 93 were joined to the stress relaxation part 92 by brazing with nickel / silver brazing.

  In this case, the stress relaxation portion 92 of the joined body 90 was molded so that the cross section thereof was a waveform.

  And while joining the separator 87 and the junction part 91 of the conjugate | zygote 90, the junction part 93 and the separator support plate 88 of the conjugate | zygote 90 were joined, and the solid oxide fuel cell 81 of this Example was obtained.

  Next, as shown in FIG. 9, the solid oxide fuel cells 81 thus obtained are sequentially stacked, and the cell support plate 6 and the separator support plate 88 are bonded and fixed to the stainless steel frame 9 via the BSAC glass 14. Thus, a stack structure having 15 levels (3 levels in FIG. 9) was obtained.

  Accordingly, air is supplied to the air electrode layer 4 side of the single cell 2 of the solid oxide fuel cell 81 in the stack structure, and hydrogen is supplied to the fuel electrode layer 3 side of the single cell 2 so that the temperature is 700 ° C. from room temperature. When the temperature was raised and lowered 30 times, not only the single cell 2 and the cell support plate 6 but also the joined portion of the single cell 2 and the joined body 10 or the separator 87 and the joined body 90 There were no defects such as cracks at the joints. As a matter of course, no gas leak occurred between the anode chamber and the cathode chamber.

  As a result, it has been demonstrated that the solid oxide fuel cell 81 and the stack structure formed by laminating the same in this embodiment have excellent durability while maintaining the required flexibility as in the past. did it.

  In addition, in this embodiment, since both the metal separator 87 and the metal separator support plate 88 can maintain flexibility, it is avoided that a contact failure occurs between the separator 87 and the current collector 8. Will be.

  In the above-described embodiments, the solid oxide fuel cells of the present invention have been described by way of example in the form of a disk, but the present invention is not limited to this, and for example, a square shape is formed. It may be.

  Further, in the above-described embodiment, the case where both the joint portion and the stress relaxation portion of the joined body are made of ferritic stainless steel has been described as an example, but the joint portion and the stress relaxation portion of the joined body are made of different materials. The Young's modulus of the stress relaxation part may be set to be larger than the Young's modulus of the joint part. For example, the joint part of the joined body is made of ferritic stainless steel, and the stress relaxation part is made of austenite. It can be made of a stainless steel.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory plan view (a) and an explanatory sectional view (b) showing one embodiment of a solid oxide fuel cell of the present invention. Example 1 It is the whole perspective explanatory drawing (a), (b) from the front and back which shows the assembly of the solid oxide fuel cell of FIG. Example 1 FIG. 2 is a cross-sectional explanatory view of a stack structure formed by stacking the solid oxide fuel cells of FIG. 1. Example 1 FIG. 4 is an overall perspective view of the current collector shown in FIG. 3. Example 1 It is a section explanatory view showing other examples of a solid oxide fuel cell of the present invention. (Example 2) FIG. 6 is a cross-sectional explanatory view showing still another embodiment of the solid oxide fuel cell of the present invention. (Example 3) FIG. 6 is a cross-sectional explanatory view showing still another embodiment of the solid oxide fuel cell of the present invention. (Example 4) FIG. 6 is a cross-sectional explanatory view showing a separator of a solid oxide fuel cell according to still another embodiment of the present invention. (Example 5) FIG. 9 is a cross-sectional explanatory view of a stack structure formed by stacking the solid oxide fuel cells of FIG. 8. (Example 5)

Explanation of symbols

1, 21, 41, 61, 81 Solid oxide fuel cell 2 Single cell 3 Fuel electrode layer (electrode layer)
4 Air electrode layer (electrode layer)
5 Electrolyte layer 6 Cell support plate 7, 87 Separator 8 Current collector 10, 30, 50, 70, 90 Junction 11, 13, 31, 33, 51, 71, 91, 93 Junction 12, 32, 52, 72 , 92 Stress relief part 88 Separator support plate

Claims (14)

  In a solid electrolyte fuel cell including a single cell formed by sandwiching an electrolyte layer between a pair of electrode layers and a metal cell support plate that supports the single cell, between the single cell and the cell support plate, A solid oxide fuel cell comprising: a high-rigidity joint that is joined to a single cell; and a joined body that includes a stress relaxation portion that is positioned around the joint and has rigidity lower than that of the joint.   A metal separator that comes into contact with a single cell via a current collector and a metal separator support plate that supports the separator, and a high-rigidity bond between the separator and the separator support plate that is also bonded to the separator 2. The solid oxide fuel cell according to claim 1, further comprising a joint and a stress relaxation portion that is positioned around the joint and has rigidity lower than that of the joint.   3. The solid electrolyte fuel according to claim 1, wherein a joint portion positioned around the stress relaxation portion of the joined body and joined to the cell support plate or the separator support plate is a joint portion having higher rigidity than the stress relaxation portion. battery.   4. The solid oxide fuel cell according to claim 3, wherein joints located across the stress relaxation part of the joined body have substantially the same cross-sectional shape. 5.   The solid oxide fuel cell according to any one of claims 1 to 4, wherein a joint portion and a stress relaxation portion of the joined body are formed of the same material.   6. The solid oxide fuel cell according to claim 5, wherein the thickness of the stress relaxation part of the joined body is made thinner than that of the highly rigid joined part to lower the rigidity.   The solid oxide fuel cell according to claim 6, wherein the stress relaxation portion of the joined body has a cross-sectional groove shape.   The solid oxide fuel cell according to claim 6, wherein the stress relaxation portion of the joined body has a cross-sectional saddle shape.   The solid oxide fuel cell according to claim 6, wherein the stress relaxation portion of the joined body has a corrugated cross section.   The solid oxide fuel cell according to any one of claims 1 to 9, wherein the joined body having the joint portion and the stress relaxation portion integrally is made of ferritic stainless steel.   The solid electrolyte according to any one of claims 1 to 4, wherein the bonded portion and the stress relaxation portion of the bonded body are formed of different materials, and the Young's modulus of the stress relaxation portion is set larger than the Young's modulus of the bonded portion. Type fuel cell.   The solid oxide fuel cell according to claim 11, wherein the joined portion of the joined body is made of ferritic stainless steel, and the stress relaxation portion is made of austenitic stainless steel.   When manufacturing the solid oxide fuel cell according to any one of claims 1 to 12, between the single cell and the cell support plate, a high-rigidity joint and a stress relaxation part with lower rigidity than the joint. A solid body characterized in that a joined body having a structure is disposed, a joined portion of the joined body is joined to a single cell, a stress relaxation portion side is joined to a cell support plate, and the single cell and the cell support plate are joined. A method for producing an electrolyte fuel cell.   A stack structure of a solid oxide fuel cell, comprising the solid oxide fuel cell according to any one of claims 1 to 12.

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