JP4470474B2 - Solid oxide fuel cell - Google Patents

Description

  The present invention provides a solid electrolyte type in which each electrode of a fuel electrode and an air electrode is formed so as to sandwich a flat plate type solid electrolyte to form a power generation unit, and a frame portion is bonded to the outer peripheral side of the power generation unit using a bonding material The present invention relates to a fuel cell.

For example, Patent Document 1 below discloses a configuration in which a fuel electrode and an air electrode are arranged on both sides of a flat solid electrolyte, and a holding thin plate frame is attached to the air electrode side surface on the outer peripheral side of the flat solid electrolyte. Has been.
JP 2000-331692 A

  In the above-described conventional solid oxide fuel cell, when the power generation unit is laminated with the separator by attaching the holding thin plate frame to the power generation unit in which the fuel electrode and the air electrode are formed so as to sandwich the solid electrolyte, In addition to closing the gap between the separator and the power generation unit and preventing mixing of the fuel gas and the oxidizing gas, the stress generated by stacking by stacking a large number of separators and power generation units, and the power generation unit and other components in the stack The structure is such that the thermal stress due to the difference in thermal expansion coefficient from the constituent members is absorbed by the holding thin plate frame.

  Therefore, in order to further reduce the stress due to the holding thin plate frame, it is desirable to make the thickness of the holding thin plate frame as thin as possible. However, when this holding thin plate frame and the power generation part are joined, the joining is mainly performed using a glass sealing material mainly composed of metal brazing or silicon oxide mainly composed of metal. The material is greatly different in coefficient of thermal expansion from metal oxide ceramics and refractory metals that make up solid oxide fuel cells, metal brazing is about 1.2 to 2 times, and glass sealing material is about half to 80%. It is.

  In particular, in a solid oxide fuel cell, since the difference between the normal temperature and the operating temperature is large, the thermal stress generated by this bonding material is also large, which may cause damage to the power generation unit, damage the holding thin plate frame, or Causes the holding thin frame to be distorted.

  When the power generation unit or the holding thin plate frame is damaged, a gas leak occurs inside the fuel cell, and the fuel gas and air are mixed and burned, resulting in a decrease in fuel utilization rate and a decrease in output. In addition, the strain of the holding thin plate frame is the same, which causes gas leakage from the laminated portion layers and causes the same adverse effect. In addition, this gas causes local temperature rise and non-uniform thermal stress distribution due to mixing and combustion, causing distortion and cracks in various parts, eventually shortening the life of the fuel cell and reducing reliability. become.

  Therefore, an object of the present invention is to reduce the thermal stress at the joint between the power generation unit and the frame and improve the reliability of the joint.

The present invention forms a power generation part by forming each electrode of a fuel electrode and an air electrode so as to sandwich a flat solid electrolyte, and joins a frame part using a joining material on the outer peripheral side of the power generation part In the solid oxide fuel cell formed by stacking the power generation unit and the separator bonded to each other, the frame includes a protrusion on the surface opposite to the bonding and corresponds to the bonding. the thickness of the portion that is rather thick than the thickness of the other portions, the corresponding surface at the junction of the said power generating portion of the frame portion, a recess continuously extending along said frame portion, the bonding material in the recess The main feature is that the region where the bonding material is exposed to an oxidizing atmosphere or a reducing atmosphere is narrowed .

According to the present invention, since the thickness of the portion corresponding to the joint portion of the frame portion is thicker than the thickness of the other portion, the thermal stress generated from the joint portion between the power generation portion and the frame portion is reduced, and the reliability of the joint portion is reduced. Can be improved.
Also, on the surface corresponding to the joint portion of the frame portion with the power generation portion, a concave portion that is continuous along the frame portion is provided, and the joint material is provided in the concave portion to form the joint portion. A region where the bonding material is exposed to an oxidizing atmosphere or a reducing atmosphere can be narrowed, and deterioration of the bonding material can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1A is a plan view showing a basic configuration of a solid oxide fuel cell according to a first reference example of the present invention, and FIG. 1B is a cross-sectional view taken along line AA in FIG. 1 (c) is an enlarged view of a portion B in FIG. 1 (b).

  As shown in FIG. 1 (b), this solid oxide fuel cell is configured to generate power by arranging a fuel electrode 3 and an air electrode 5 on both sides thereof so as to sandwich a flat solid electrolyte 1 as a base material. A unit cell 7 is configured as a unit.

For example, yttria-stabilized zirconia (hereinafter YSZ) is used for the solid electrolyte 1, NiO / YSZ cermet is used for the fuel electrode 3, and (LaxSr1-x) CoO ₃ (hereinafter LSC) is used for the air electrode. It is baked at high temperature on YSZ of the material (solid electrolyte 1).

  The above-described solid electrolyte 1 has an outer peripheral portion protruding over the entire circumference with respect to the fuel electrode 3 and the air electrode 5, and a frame 9 as a frame portion is attached to the protruding portion on the air electrode 5 side.

  The frame 9 is made of a ferritic stainless steel thin plate having a thermal expansion coefficient close to that of the material constituting the solid electrolyte 1 and excellent in heat resistance, and has an opening 11 larger than the region of the air electrode 5 of the single cell 7 at the center. Is formed. Further, in the four directions around the frame 9, the oxidizing gas and the fuel gas are supplied to and discharged from the single cell 7 through the oxidizing gas supply port 13 and the exhaust port 15, and the fuel gas supply port 17 and the exhaust port 19. It is provided.

  Then, as shown in FIG. 1C, the joining portion 21 between the solid electrolyte 1 and the frame 9 is a metallic brazing material having a high joining temperature, for example, mainly composed of gold, silver, nickel, palladium. It joins using the joining material 23 which consists of. The frame 9 has a projection 9 i formed on the surface opposite to the bonding material 23, so that the portion corresponding to the bonding portion 21 of the frame 9 is thicker than the other portions.

  The thickness of the frame 9 excluding the protrusion 9i is about several tens of μm. The protrusion 9i has a width of about several mm and a height (thickness) of about several tens to 100 μm. It is provided all around. The frame 9 having such a structure is manufactured by pressing or etching a stainless alloy foil thinned by rolling or the like.

  The structure in which the frame 9 is joined to the single cell 7 shown in FIG. 1 is referred to as a cell plate 25 in the following description. FIG. 2 is an exploded perspective view showing components of the entire fuel cell including the cell plate 25.

  Spacers 27 and 29 made of an electrically insulating material are disposed on both the upper and lower sides of the cell plate 25 in FIG.

  The upper spacer 27 connects between the oxidizing gas supply port 13 and the exhaust port 15 of the cell plate 25 and has an opening 31 in the center for supplying oxidizing gas to the surface of the air electrode 5 of the single cell 7. In addition, through holes 33 and 35 respectively aligned with the fuel gas supply port 17 and the exhaust port 19 of the cell plate 25 are provided outside the opening 31.

  On the other hand, the spacer 29 on the lower side has an opening 37 for connecting the fuel gas supply port 17 and the exhaust port 19 of the cell plate 25 and supplying fuel gas to the surface of the fuel electrode 3 of the single cell 7. In addition, through holes 39 and 41 respectively aligned with the oxidizing gas supply port 13 and the exhaust port 15 of the cell plate 25 are provided outside the opening 37.

On the side opposite to the cell plate 25 of the spacer 27 (or on the side opposite to the cell plate 25 of the spacer 29), a separator 43 made of a conductive material capable of gas separation, for example, ceramic such as LaCrO ₃ is provided. Deploy.

  The separator 43 includes through holes 45, 47, 49, and 51 that are aligned with the oxidizing gas supply port 13 and the exhaust port 15 and the fuel gas supply port 17 and the exhaust port 19 of the cell plate 25, respectively.

  Further, metal meshes 53 and 55 for current collection are arranged on the surfaces of the fuel electrode 3 and the air electrode 5 in the single cell 7, respectively, and the plurality of single cells 7 to be stacked include the metal meshes 53 and 55 and separators. 43 is connected in series.

  3 is a cross-sectional view corresponding to a cross section taken along the line C-C in the separator 43 shown in FIG. 2 when two single cells 7 are stacked and assembled, and FIG. 4 is equivalent to a cross section taken along the line D-D. It is sectional drawing.

  3 shows the flow of the fuel gas from the fuel gas inlet manifold 57 constituted by the fuel gas supply port 17 of the cell plate 25, the through hole 33 of the spacer 27, the opening 37 of the spacer 29, and the through hole 49 of the separator 43. Fuel gas is supplied, and this fuel passes through the fuel electrode 3 of each single cell 7 and is consumed for power generation. Thereafter, surplus fuel gas is exhausted from the fuel gas outlet manifold 59 formed by the fuel gas exhaust port 19 of the cell plate 25, the through hole 35 of the spacer 27, the opening 37 of the spacer 29, and the through hole 51 of the separator 43.

  4 shows the flow of the oxidizing gas, from the oxidizing gas inlet manifold 61 constituted by the oxidizing gas supply port 13 of the cell plate 25, the opening 31 of the spacer 27, the through hole 39 of the spacer 29, and the through hole 45 of the separator 43. An oxidizing gas is supplied, and this oxidizing gas passes through the air electrode 5 of each single cell 7 and is consumed for power generation. Thereafter, excess oxidizing gas is exhausted from an oxidizing gas outlet manifold 63 constituted by the oxidizing gas exhaust port 15 of the cell plate 25, the opening 31 of the spacer 27, the through hole 41 of the spacer 29, and the through 47 of the separator 43.

  By generating such a flow of fuel gas and oxidizing gas, power is generated in each single cell 7 and the fuel cell is started. At this time, particularly in the case of a solid oxide fuel cell, the operating temperature is as high as about 800 ° C. due to the limitation due to its operating principle.

  Here, the frame 9 is interposed in order to relieve the stress from the whole fuel cell to the single cell 7, but in order to further reduce the stress by this frame 9, the thickness of the frame 9 should be made as thin as possible. desirable. However, when the frame 9 and the power generation unit (single cell 7) are joined, they are joined using a glass sealing material mainly composed of metal brazing or silicon oxide mainly composed of metal. This material has a large thermal expansion coefficient different from that of the metal oxide ceramic or heat-resistant metal constituting the solid oxide fuel cell, so that the thermal stress generated by this bonding material is also large, which causes damage to the power generation section.

For this reason, in the first reference example described above, as shown in FIG. 1 (c), the protrusion 9i as a reinforcing portion is provided at the inner end of the frame 9, thereby reducing the thickness of the entire frame 9. The strength of the joint portion 21 is improved by increasing the thickness of only the portion corresponding to the joint portion 21 while keeping it as it is. As a result, the expansion and contraction due to the temperature change of the bonding material 23 are suppressed by the strength of the frame 9 to prevent the bonding portion 21 from being damaged, and the thin frame 9 can be prevented from being damaged and the frame 9 can be prevented from being deformed .
As a result, the occurrence of gas leakage from the joint 21 can be prevented, the fuel utilization rate can be prevented from lowering due to the mixing / combustion of the fuel gas and the oxidizing gas, and the output can be prevented from being lowered. It is possible to prevent the rise and non-uniformity of thermal stress distribution, and to achieve a long life as a fuel cell.

FIG. 5 (a) is a plan view of a solid oxide fuel cell showing a second reference example of the present invention, and FIG. 5 (b) is an enlarged EE cross-sectional view of FIG. 5 (a). In FIG. 5A, the oxidizing gas supply port 13, the exhaust port 15, the fuel gas supply port 17, and the exhaust port 19 shown in FIG. 1A are omitted. In the second reference example , two protrusions 9i1 and 9i2 are provided on the entire circumference so as to be parallel to each other as reinforcing portions. Three or more such protrusions may be provided.

FIG. 6A is a plan view of the main part of a solid oxide fuel cell according to a third reference example of the present invention, and FIG. 6B is a cross-sectional view taken along line FF in FIG. In this reference example , the two protrusions 9i1 and 9i2 in the second reference example shown in FIG. 5 are connected to each other by a connecting protrusion 9j. The connecting projections 9j are provided over the entire circumference at equal intervals along the extending direction of the projections 9i1 and 9i2, and the projections 9i1 and 9i2 and the connecting projections 9j form a ladder shape as shown in FIG. Form. As shown in FIG. 6B, the protrusions 9i1 and 9i2 and the connection protrusion 9j have the same height, and constitute a reinforcing part.

FIG. 7A is a plan view of the main part of a solid oxide fuel cell showing a fourth reference example of the present invention, and FIG. 7B is a cross-sectional view taken along the line GG of FIG. This reference example is provided with cross projections 9m and 9n that intersect with each other between adjacent connection projections 9j after widening the interval between the connection projections 9j in the third reference example shown in FIG. These projecting portions 9i1, 9i2, connecting projecting portions 9j and intersecting projecting portions 9m, 9n form a beam structure as shown in FIG. The protrusions 9i1, 9i2, the connecting protrusion 9j, and the cross protrusions 9m, 9n have the same height as shown in FIG. 7B, and constitute a reinforcing part.

In this way, as in each of the reference examples shown in FIGS. 5 to 7 described above, the reinforcing portion is divided into two protrusions 9i1 and 9i2, or a ladder shape or a beam structure is used to increase the strength. While securing, it is possible to reduce the weight as compared with the case where one wide protruding portion 9i is provided as in the first embodiment, and the weight can be reduced by reducing the height.

In each of the reference examples described above, the single cell 7 and the frame 9 are both rectangular, but other shapes such as a circle or an ellipse may be used, and a plurality of openings 11 may be formed in one frame 9. The present invention can also be applied to a configuration in which the single cells 7 are arranged corresponding to the openings 11, that is, a configuration in which the single cells 7 are arranged in parallel.

FIG. 8 is a cross-sectional view corresponding to FIG. 1C, showing the first embodiment of the present invention. The example of FIG. 8A is provided with a convex portion 9a that protrudes toward the solid electrolyte 1 at the edge on the opening 11 side of the frame 9 with respect to the first reference example shown in FIG. Thereby, the frame 9 in the outer part of the convex portion 9a has the concave portion 9b. The convex portion 9 a is provided on the entire circumference of the opening 11, and a bonding material 23 is provided at a portion of the concave portion 9 b on the outer side facing the solid electrolyte 1, and this is used as the bonding portion 21.

  When the fuel cell is started up, particularly in the case of a solid oxide fuel cell, the operating temperature becomes as high as about 800 ° C. due to the limitation due to its operating principle as described above.

  However, in the example of FIG. 8A described above, the projection 9 a is provided at the inner end of the frame 9 to cover the bonding material 23, so that the bonding material 23 made of metal brazing is in the air electrode 5. Exposure to a high-temperature oxidizing atmosphere can be prevented, and the progress of oxidation in a high-temperature oxidizing atmosphere unavoidable for metal materials can be suppressed.

  Thereby, deterioration such as corrosion and erosion of the bonding material 23 can be suppressed, deterioration of the sealing performance at the bonding portion 21 can be prevented, and occurrence of gas leakage from the bonding portion 21 can be prevented. In addition, by preventing the occurrence of gas leaks, it is possible to prevent a decrease in fuel utilization and output due to mixing and combustion of fuel gas and oxidant gas, as well as local temperature increase due to the above-mentioned combustion, and a lack of thermal stress distribution. Uniformity can be prevented and a long life as a fuel cell can be achieved.

8B is different from the first reference example shown in FIG. 1C in that a recess 9c is provided on the opening 11 side of the frame 9, and the contact surface 9d of the frame outside the recess 9c is solid. It is in contact with the electrolyte 1. Thereby, in this example, the contact surface 9d is brought into contact with the solid electrolyte 1, whereby the bonding material 23 can be prevented from being exposed to the reducing atmosphere on the fuel electrode 3 side. Therefore, when a material mainly composed of an oxide such as glass is used for the bonding material 23, it is possible to prevent the oxide-based bonding material 23 from being reduced in a reducing atmosphere.

  Thereby, even when the bonding material 23 is made of an oxide, it is possible to obtain the same effect as in the example of FIG. 8A that the deterioration of the bonding material 23 can be prevented and the occurrence of gas leak can be prevented.

  The example of FIG. 8C is a combination of the examples of FIG. 8A and FIG. 8B. A groove 9e as a recess is provided in a portion of the frame 9 facing the solid electrolyte 1, and the groove 9e The inner convex portion 9 a is in contact with the solid electrolyte 1, and the outer contact surface 9 d of the groove 9 e is in contact with the solid electrolyte 1.

  In other words, the convex portion 9a and the contact surface 9d cover and confine both the inside and outside of the bonding material 23, and the bonding material 23 can be prevented from being exposed to both the oxidizing atmosphere and the reducing atmosphere. .

  For this reason, in the example of FIG. 8C, the same effect as the example of FIGS. 8A and 8B can be obtained, and since it is difficult to be exposed to either atmosphere, resistance to the atmosphere is selected in the selection of the bonding material 23. Therefore, the choice of the bonding material 23 can be expanded, and a cheaper bonding material 23 and an easy-to-handle bonding material 23 can be employed.

Figure 9 shows a second embodiment of the present invention. In this embodiment, with respect to the example of FIG. 8C, two grooves 9f are provided in a portion facing the solid electrolyte 1, and a bonding material 23 is provided in the two grooves 9f, which are connected to the bonding portion 21. It is said.

  In order to ensure reliability in the joint portion 21, it is desirable to set the width wide. However, if the width is excessively large, as shown in FIG. 10, a large stress is generated not only in the circumferential direction but also in the width direction (F). May occur, and the stress in the two directions may cause damage to the single cell 7 or distortion of the frame 9. However, according to the sixth embodiment, by dividing the bonding material 23 into two parts to reduce the width, the stress in the width direction is reduced as shown in FIG. The stress generated from can be reduced. Further, reliability can be ensured by forming the bonding material 23 in a plurality of rows.

FIG. 11A is a plan view of the frame 9 as viewed from the solid electrolyte 1 side, showing a third embodiment of the present invention, and FIG. 11B is a cross-sectional view taken along line HH in FIG. FIG. 10 is a cross-sectional view corresponding to FIG. In this embodiment, a single groove 9g is provided in a portion of the frame 9 that faces the solid electrolyte 1, and the straight line portion is subdivided so that the groove 9g is not formed linearly but is bent along the frame 9. The structure is different from the example of FIG.

  When the groove 9e is linearized as shown in FIG. 8C, the stress F generated in the whole is large as shown in FIG. 12A, but the structure in which the groove 9g is bent as shown in FIG. By doing so, as shown in FIG. 12B, the dimensional change due to the temperature change is also divided, and the generated stress F is also reduced.

As described above, in the third embodiment, it is possible to reduce macro stress generated in the circumferential direction by dividing the linear portion.

FIG. 13A is a cross-sectional view of the cell plate 25 corresponding to FIG. 1B, showing a fifth reference example of the present invention. This reference example uses a so-called electrode-supported single cell 70 in which the fuel electrode 30 is a base material, the solid electrolyte 1 is disposed thereon, and the air electrode 5 is disposed thereon.

  FIG. 13B is a cross-sectional view showing details of the joint portion 21 between the frame 9 and the solid electrolyte 1 in FIG. 13A, and the end portion on the outer peripheral side of the solid electrolyte 1 is from the same end portion of the fuel electrode 30. The bonding material 23 is provided between the frame 9 and the stationary electrolyte 1 and between the frame 9 and the fuel electrode 30 so as to be located inside and to cover the outer peripheral end of the solid electrolyte 1 in this state. Yes.

  FIG. 13C shows an example in which two protrusions 9i1 and 9i2 are provided as reinforcing portions on the frame 9 as shown in FIG. 5B.

FIG. 13D shows a fourth embodiment in which a groove 9 e is provided in a portion of the frame 9 that faces the solid electrolyte 1, and a bonding material 23 is provided on the outer periphery side of the groove 9 e and the solid electrolyte 1. .

Figure 14 (a), (b) , (c) shows a sixth reference example according to the diagram 13 and the same electrode support type single cell 70. In this reference example , as shown in FIG. 14A, the frame 9 is joined to the fuel electrode 30 on the side opposite to the solid electrolyte 1 via a joining portion 21. Further, in this example, a sealing material 65 is provided from the solid electrolyte 1 to the frame 9 so as to cover the side portion of the fuel electrode 30 outside the joint portion 21.

  FIG. 14B is a cross-sectional view showing details of the joint portion 21 between the frame 9 and the fuel electrode 30 in FIG. 14A, and is the opposite side of the joint material 23 of the frame 9 as in FIG. Is provided with a protrusion 9i.

  In FIG. 14C, two projecting portions 9i1 and 9i2 are provided as reinforcing portions.

FIG. 14D shows a fifth embodiment in which a groove 9e is provided in a portion of the frame 9 facing the solid electrolyte 1, and a bonding material 23 is provided in the groove 9e.

  According to the present invention, by providing the reinforcing portion on the surface opposite to the joint portion of the frame portion, the thermal stress generated from the joint portion between the power generation portion and the frame portion is reduced, and the reliability of the joint portion is improved. can do.

  By making the reinforcing part a protrusion provided on the surface opposite to the joint part of the frame part, thermal stress generated from the joint part between the power generation part and the frame part is reduced, and the reliability of the joint part is improved. Can be improved.

  Since the protrusion is continuous along the frame portion, the thermal stress generated from the joint between the power generation portion and the frame can be reliably reduced, and the reliability of the joint can be reliably improved. .

  A concave portion that is continuous along the frame portion is provided on a surface corresponding to a joint portion of the frame portion with the power generation portion, and the bonding material is provided in the concave portion to form the joint portion. By enclosing, the region where the bonding material is exposed to an oxidizing atmosphere or a reducing atmosphere can be narrowed, and deterioration of the bonding material can be prevented.

  Since the concave portion is constituted by a groove, and the groove is provided in a plurality of rows along the frame portion, the bonding material can be divided into a plurality of portions to reduce the width, and the stress generated from each row of the bonding material is reduced. Can be made. Further, reliability can be ensured by arranging the bonding materials in a plurality of rows.

  It is possible to reduce the macro stress generated in the circumferential direction by dividing the linear portion by forming the concave portion with a groove and bending the groove along the frame portion.

(A) is a plan view showing a basic configuration of a solid oxide fuel cell according to a first reference example of the present invention, (b) is a cross-sectional view taken along line AA in (a), and (c) is a portion B in (b). FIG. It is a disassembled perspective view which shows the structural member of the whole fuel cell containing the cell board by a 1st reference example . FIG. 3 is a cross-sectional view corresponding to a cross section taken along the line CC of the separator shown in FIG. 2 when two single cells according to the first reference example are stacked and assembled. It is sectional drawing equivalent to the DD sectional view in the separator of FIG. 2 of the state which laminated | stacked and assembled two single cells by the 1st reference example . (A) is a top view of the solid oxide fuel cell which shows the 2nd reference example of this invention, (b) is expanded EE sectional drawing of (a). (A) is a top view of the principal part of the solid oxide fuel cell which shows the 3rd reference example of this invention, (b) is FF sectional drawing of (a). (A) is a top view of the principal part of the solid oxide fuel cell which shows the 4th reference example of this invention, (b) is GG sectional drawing of (a). Shows a first embodiment of the present invention, it is a cross-sectional view corresponding in Figure 1 (c). It is sectional drawing corresponding to FIG.1 (c) which shows the 2nd Embodiment of this invention. It is supplementary explanatory drawing of 2nd Embodiment. (A) is the top view seen from the solid electrolyte side of the flame | frame which shows the 3rd Embodiment of this invention, (b) is sectional drawing corresponding to the HH line | wire cross section of (a), and corresponding to FIG. It is. It is supplementary explanatory drawing of 3rd Embodiment. (A) is a cross-sectional view of a cell plate corresponding to FIG. 1 (b), showing a fifth reference example of the present invention, and (b) is a cross-section showing details of the joint between the frame and the solid electrolyte in (a). FIG, (c) is a sectional view, (d) is shown to cross-sectional view of a fourth embodiment shaped state showing another example of the fifth reference example. (A) is a cross-sectional view of a cell plate corresponding to FIG. 1 (b), showing a sixth reference example of the present invention, and (b) is a cross-section showing details of the joint between the frame and the solid electrolyte in (a). FIG, (c) is a sectional view, (d) is shown to cross-sectional view of a fifth embodiment forms state of showing another example of the sixth embodiment.

Explanation of symbols

1 Solid electrolyte 3,30 Fuel electrode 5 Air electrode 7,70 Single cell (power generation unit)
9 frame (frame part)
9b, 9c Recess 9e, 9f, 9g Groove (recess)
9i Protruding part (reinforcing part)
9j Connecting protrusion (reinforcing part)
9m, 9n Intersection protrusion (reinforcement part)
21 Joining part 23 Joining material 43 Separator

Claims (4)

Forming each electrode of the fuel electrode and the air electrode so as to sandwich the solid electrolyte of the flat plate type to form a power generation part, and provided with a joint part for joining the frame part using a joining material on the outer peripheral side of this power generation part, In the solid oxide fuel cell formed by laminating the power generation unit and the separator bonded to the frame portion , the frame portion includes a protrusion on the surface opposite to the bonding portion and has a thickness corresponding to the bonding portion. Saga rather thickness than the thickness of the other portions, the corresponding surface at the junction of the said power generating portion of the frame portion, the concave portion continuously extending along the frame part is provided, said the bonding material disposed in the recess A solid oxide fuel cell, characterized in that a region where the bonding material is exposed to an oxidizing atmosphere or a reducing atmosphere is narrowed . The protrusions solid oxide fuel cell according to claim 1, characterized in that in succession along said frame portion. 3. The solid oxide fuel cell according to claim 1, wherein the concave portion is constituted by a groove, and a plurality of the grooves are provided along the frame portion. 3. The solid oxide fuel cell according to claim 1, wherein the concave portion is constituted by a groove, and the groove is bent along the frame portion.

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