JP5679893B2 - Solid oxide fuel cell and method for producing the same - Google Patents

Description

  The present invention includes a cell main body in which at least a fuel electrode layer, an air electrode layer, and a solid electrolyte layer are laminated, a metal separator that separates the fuel gas flow path and the air flow path, and a metal frame that surrounds the cell main body. The present invention relates to a flat solid oxide fuel cell having

  Conventionally, a flat-type solid oxide fuel cell (SOFC) is known. In general, a flat SOFC has a cell body formed by disposing a fuel electrode layer in contact with a fuel gas on one side of a solid electrolyte layer and an air electrode layer in contact with an oxidant gas (air) on the other side. The cell main body is joined to a metal separator to isolate the fuel gas flow path and the oxidant gas flow path. The metal separator is made of, for example, a frame-shaped metal plate, and is integrally joined to the cell body in a region surrounding the opening. Furthermore, the metal separator with which the cell main body is integrated is integrally joined with a metal frame surrounding the cell main body (see, for example, Patent Document 1). In general, when a metal frame and a metal separator are joined together, a structure capable of obtaining good gas sealing properties is required. For example, welding without using a brazing material or welding (brazing) using a brazing material. The joining method is known.

JP 2007-207668 A

  In the structure in which the metal frame and the metal separator are integrated, the fuel gas flow path and the air flow path exist above and below the gas frame, so it is necessary to arrange a gas seal member for sealing each flow path. . For example, when a gas seal member is disposed on the upper part of a metal frame integrated with a metal separator, it is necessary to maintain sufficient adhesion of the gas seal member in order to maintain good gas leakage. However, when the metal frame and the metal separator are joined by welding, the welded portion is heated to form a projection, and the flatness of the surface cannot be maintained. Further, even when joining by brazing, a protrusion may be formed on the cell surface due to brazing pool or the like. Therefore, when the gas seal member is disposed on the upper part of the metal frame integrated with the metal separator, the bottom surface of the gas seal member comes into contact with the protruding portion, and the adhesion may be impaired. As a result, there is a problem that the gas leak property of the unit cell is deteriorated, for example, gas leak partially occurs due to insufficient adhesion of the gas seal member.

  The present invention has been made to solve these problems, and is a solid oxide capable of maintaining good gas leakage of a unit cell even when a metal frame and a metal separator are welded together. An object is to provide a fuel cell.

  In order to solve the above-mentioned problems, a solid oxide fuel cell according to the present invention includes a fuel electrode in contact with a fuel gas, an air electrode in contact with an oxidant gas, and the fuel electrode disposed on one side and the other side. In a solid oxide fuel cell comprising a solid electrolyte layer having the air electrode disposed on the side, the fuel cell is divided into a first region on the outer peripheral side and a second region on the inner peripheral side, and the surface of the second region is A frame-shaped metal frame having a step structure formed lower than a surface of the first region by a predetermined height, and a fuel gas flow path that is welded and joined to the surface of the second region of the metal frame. And a metal separator that separates the flow path of the oxidant gas, and a frame-shaped gas seal member that is disposed in close contact with the surface of the first region of the metal frame. The inner peripheral side protrudes above the second region, Welded parts of the genus separator is characterized in that the predetermined height so that the gas sealing member and the non-contact state is set.

  According to the solid oxide fuel cell of the present invention, the metal separator that separates the flow path of the fuel gas and the flow path of the oxidant gas in the unit cell is welded to the metal frame, and the gas seal member is further bonded to the metal frame. The metal frame is provided with a step structure, the gas seal member is disposed in close contact with the surface of the first region on the outer peripheral side, and the surface of the second region on the inner peripheral side that is lower than the first region. A metal separator is welded together. When the metal separator is welded and joined to the surface of the second region, a welding projection (or a projection due to the brazing material pool) is formed at the welded portion of the metal separator by heating, but due to the step structure of the metal frame, the welding projection Is kept in contact with the bottom surface of the upper gas seal member. Therefore, the adhesion between the gas seal member and the metal frame is not impaired after the formation of the weld projection, and the metal separator is not exposed on the side surface of the unit cell, and good gas sealability can be maintained.

  For example, a cell body in which a fuel electrode layer, an air electrode layer, and a solid electrolyte layer are laminated can be joined to the metal separator. In this case, it is desirable to arrange in such a positional relationship that the surface of the cell body (for example, the surface of the air electrode layer) is exposed from the opening formed in the metal frame.

  The metal frame and the gas seal member can be arranged in various positional relationships. For example, the metal frame and the gas seal member are formed such that end portions on the outer peripheral side thereof are in the same position in plan view, and the gas seal member has an end portion on the inner peripheral side of the metal frame. You may form the edge part of an inner peripheral side in the position near inner periphery by planar view. With such a structure, the presence of the gas seal member protruding above the second region can suppress deformation due to the flexible thin metal separator bending upward.

Dimension conditions associated with the step structure of the metal frame is not specifically limited, for example, the predetermined height, it is desirable to set the above values plus 0.1mm thickness of the gold Shokuse separator. Generally, since the welding projection formed by welding joining has a height sufficiently lower than 0.1 mm, such a setting can reliably avoid the situation where the welding projection contacts the upper gas seal member. For example, the metal separator is preferably formed with a thickness in the range of 30 μm to 200 μm from the balance between flexibility and strength. With the above settings, the step structure of the metal frame can be easily formed while taking into consideration the thickness of the metal separator and the height of the weld projection.

  As the gas seal member, various insulating materials that can maintain gas leakage can be used. For example, the gas seal member can be formed using insulating mica.

In order to solve the above problems, a method for producing a solid oxide fuel cell according to the present invention includes a fuel electrode in contact with the fuel gas, an air electrode in contact with an oxidant gas, and the fuel electrode on one surface side. And a solid electrolyte layer having the air electrode disposed on the other surface side, wherein the fuel gas flow path and the oxidant gas flow path are separated from each other A first step of welding and joining a metal separator to be adhered to a surface of the second region of the frame-shaped metal frame divided into a first region on the outer peripheral side and a second region on the inner peripheral side A second step of joining the cell body integrally laminated with the fuel electrode, the solid electrolyte layer, and the air electrode to a metal separator welded to the metal frame, and an insulating frame shape the gas sealing member, the first territory of the metal frame The metal frame has a step structure in which the surface of the second region is formed to be lower than the surface of the first region by a predetermined height, The predetermined height is set so that the inner peripheral side of the gas seal member protrudes above the second region, and the welded portion of the metal separator is not in contact with the gas seal member. Yes.

  According to the method for manufacturing a solid oxide fuel cell of the present invention, since the welded joint is used to integrate the metal frame and the metal separator in the first step, for example, compared to the case of using brazing. In addition to simplifying the process, it is possible to prevent deterioration of gas leakage by the action of the step structure. In the first step, for example, laser welding can be applied as a welding joining method for joining the metal separator to the surface of the second region.

  According to the present invention, when the metal separator constituting the unit cell is welded to the metal frame, the weld projection formed by heating contacts the bottom surface of the upper gas seal member by providing the metal frame with a step structure. Therefore, it is possible to realize a solid oxide fuel cell capable of maintaining good gas sealing performance of the unit cell while maintaining sufficient adhesion between the gas sealing member and the metal frame.

It is a side view of the solid oxide fuel cell of this embodiment. FIG. 2 is a top view of the solid oxide fuel cell of FIG. 1. It is a typical section structure figure of the state where each constituent element was disassembled about one unit cell. It is a top view of an interconnector in a unit cell. It is a top view of a gas seal member in a unit cell. It is a figure which shows the structure of the metal frame in a unit cell. It is a plane structure figure of the metal separator in a unit cell. It is a top view of a cell body in a unit cell. It is a characteristic sectional structure figure in a unit cell of this embodiment. It is a figure explaining the process relevant to a characteristic structure among the manufacturing processes of the unit cell of this embodiment.

  Hereinafter, an embodiment of a solid oxide fuel cell to which the present invention is applied will be described in detail. FIG. 1 shows a side view of the solid oxide fuel cell 1 of the present embodiment, and FIG. 2 shows a top view of the solid oxide fuel cell 1 of FIG. 1 corresponds to a side view seen from the direction of arrow A in FIG.

  As shown in FIGS. 1 and 2, the solid oxide fuel cell 1 of the present embodiment is a fuel cell stack in which a plurality of fuel cell cells (hereinafter referred to as unit cells) 3, which are basic structural units, are stacked. 2 is provided. The fuel cell stack 2 is integrally fixed by a plurality of bolts B1 to B8 and a plurality of nuts N. Of the bolts B1 to B8, the four bolts B1, B3, B5, and B7 located at the four corners in the rectangular plane of FIG. 2 are used only as connecting members for fixing the fuel cell stack 2. On the other hand, among the bolts B1 to B8, the four bolts B2, B4, B6, and B8 located on the four sides in the rectangular plane of FIG. 2 communicate with the through holes along the stacking direction in addition to the connecting members. These function as a part of a fuel gas flow path (fuel gas flow path) or an oxidant gas flow path (air flow path). Specifically, the bolt B2 communicates with the fuel gas introduction pipe Fin on the inlet side of the fuel gas flow path, and the bolt B6 opposite to the bolt B2 communicates with the fuel gas discharge pipe Fout on the outlet side of the fuel gas flow path. . Further, the bolt B4 communicates with the air introduction pipe Ain on the inlet side of the air flow path, and the bolt B8 at a position opposite to the bolt B4 communicates with the air discharge pipe Aout on the outlet side of the air flow path.

  Next, the basic structure of the unit cell 3 included in the solid oxide fuel cell 1 of FIG. 1 will be described. FIG. 3 shows a schematic cross-sectional structure of each unit cell 3 in a state where each component is disassembled. The unit cell 3 shown in FIG. 3 includes a cell body 10 that performs a power generation function. The cell body 10 is formed by laminating a fuel electrode layer 11, a solid electrolyte layer 12, and an air electrode layer 13 in order from the lower layer side. The unit cell 3 includes a pair of upper and lower interconnectors 20, 21, a fuel electrode side current collector 22 disposed between the lower interconnector 20 and the fuel electrode layer 11, and an upper interconnector 21. The air electrode side current collector 23 disposed between the air electrode layer 13, the metal frame 24 surrounding the side surface of the fuel electrode layer 11, and the cell body 10 are integrally joined to the fuel electrode layer 11 side. A metal separator 25 that separates the fuel gas flow path Fp from the air electrode layer 13 and a gas seal member 26 disposed between the metal frame 24 and the lower interconnector 20; And a gas seal member 27 disposed between the metal separator 25 and the upper interconnector 21.

  The fuel electrode layer 11 is in contact with a fuel gas serving as a hydrogen source and functions as an anode of the unit cell 3. Since the fuel electrode layer 11 serves as a support base layer that supports the cell body 10, it is desirable to form the fuel electrode layer 11 with a sufficient thickness to ensure mechanical strength. For example, as the material of the fuel electrode layer 11, cermet made of metal particles such as Ni and ceramic particles can be used. The solid electrolyte layer 12 is made of various solid electrolytes having ionic conductivity. For example, as the material of the solid electrolyte layer 12, YSZ, ScSZ, SDC, GDC, perovskite oxide, or the like can be used. The air electrode layer 13 is in contact with air gas serving as an oxygen source and functions as a cathode of the unit cell 3. For example, as the material of the air electrode layer 13, perovskite oxides, various noble metals, and cermets of noble metals and ceramics can be used. The fuel electrode layer 11, the solid electrolyte layer 12, and the air electrode layer 13 all have a square (eg, square) planar shape.

  Hereinafter, the structure of the main constituent members in the unit cell 3 will be described with reference to FIGS. 4 to 9 are the same as those in FIG. 2 in the plane. First, the lower interconnector 20 is responsible for electrical connection with the unit cell 3 adjacent to the lower layer, and the upper interconnector 21 is responsible for electrical connection with the unit cell 3 adjacent to the upper layer. As shown in FIG. 4, the interconnectors 20 and 21 are thin metal plates made of, for example, ferritic stainless steel, and eight round holes through which the bolts B1 to B8 pass are formed in the outer edge portions. The fuel electrode side current collector 22 joined to the lower interconnector 20 is made of, for example, Ni felt having air permeability, and the air electrode side current collector 23 joined to the upper interconnector 21 is For example, it consists of a metal and a conductive ceramic.

  The lower gas seal member 26 is made of, for example, an insulating material such as mica, and serves to seal the fuel gas flow path Fp in the unit cell 3. As shown in FIG. 5, an opening 30 is formed at the center of the frame-like gas seal member 26, and eight round holes through which the bolts B1 to B8 pass are formed at the outer edge. Of these, the opening 30 is formed with four notches that extend to the outer edge on two opposing sides of the square. As will be described later, the notch formed in the opening 30 becomes a part of the fuel gas flow path Fp. Since the upper gas seal member 27 has a planar structure obtained by rotating the gas seal member 26 of FIG. 5 by 90 degrees in a plane, the description thereof is omitted. In this case, the notch formed in the opening 30 of the upper gas seal member 27 becomes a part of the air flow path Ap.

  The metal frame 24 is made of a metal material such as ferritic stainless steel, for example, and has a role of fixing the cell body 10 and the metal separator 25 to the unit cell 3. 6A shows a plan view of the metal frame 24, and FIG. 6B shows a side view of the AA cross section of FIG. 6A. As shown in FIG. 6A, an opening 31 is formed in the center of the frame-shaped metal frame 24, four openings 32 are formed along each of the four sides, and four corners are formed at the four corners. Four round holes corresponding to the bolts B1, B3, B5, and B7 are formed. The central opening 31 faces the rectangular portion of the opening 30 (FIG. 5) of the gas seal member 26, but is not formed with a notch. The four openings 32 on each side are formed in a groove shape extending on both sides in the side direction from a portion overlapping each round hole of the interconnector 20 (21) and the gas seal member 26 (27).

  Therefore, the fuel gas flow path Fp from the bolt B2 on the inlet side to the bolt B6 on the outlet side through the surface of the fuel electrode layer 11 has a round hole on each of the two sides of the interconnector 20 and the gas seal member 26, and a metal. Each of the opening portions 32 on the two sides of the frame 24 and the cutouts of the opening portions 30 of the gas seal member 26 are included. The air flow passage Ap extending from the bolt B4 on the inlet side to the bolt B8 on the outlet side via the surface of the air electrode layer 13 has a round hole on each of the two sides of the interconnector 21 and the gas seal member 27, and a gas seal. Each of the cutouts of the opening 30 of the member 27 is formed (the cutout of the opening 30 of the gas seal member 26 in FIG. 5 is formed at a position rotated 90 degrees).

  As shown in FIG. 6B, the cross-sectional structure of the metal frame 24 is formed at different heights on the outer peripheral side and the inner peripheral side. That is, the metal frame 24 is divided into an outer peripheral region R1 and an inner peripheral region R2 (around the opening 31), and the surface of the region R1 is higher than the surface of the region R2 with respect to the respective bottom surfaces. Is set. Thus, the metal frame 24 is formed with a step structure S based on regions R1 and R2 having different heights. The step structure S is provided for welding the metal separator 25 to the surface of the region R2, and a more specific joining structure will be described later.

  Next, the metal separator 25 is formed into a frame-shaped thin plate having a thickness of about 0.02 to 0.3 mm using a metal material having flexibility, such as a ferritic stainless steel. As shown in FIG. 7, an opening 33 is formed in the center of the metal separator 25. The overall shape of the metal separator 25 is a square smaller in size than the metal frame 24 and the gas seal member 27 and further smaller in size than the boundary portion between the regions R1 and R2 of the metal frame 24. The opening 33 of the metal separator 25 is a square facing the opening 31 of the metal frame 24, is smaller in size than the opening 31 of the metal frame 24, and is smaller than the opening 30 of the gas seal member 27. A square with a large size.

  As shown in FIG. 8, the cell body 10 has a square outer peripheral shape. Since the cell body 10 is joined to the metal separator 25, the cell body 10 has a rectangular outer peripheral shape that is smaller in size than the outer peripheral shape of the metal separator 25 and larger in size than the opening 33 of the metal separator 25. On the other hand, the outer peripheral shape of the upper air electrode layer 13 of the cell main body 10 is a square smaller in size than the outer peripheral shape of the cell main body 10 and smaller in size than the opening 33 of the metal separator 25. As a result, as described with reference to the cross-sectional structure of FIG. 3, the structure in which the air electrode layer 13 can be exposed from the opening 33 in a state where the outer peripheral side of the cell body 10 is bonded to the metal separator 25 can be obtained. .

  Hereinafter, a characteristic cross-sectional structure of the unit cell 3 of the present embodiment will be described with reference to FIG. FIG. 9A is a diagram showing a partial cross-sectional structure of the unit cell 3 (FIG. 3) according to the present embodiment, in the vicinity of the left end including the metal frame 24, the metal separator 25, and the gas seal member 27. The part is shown enlarged. As described above, the metal frame 24 is divided into the region R1 having the width W1 on the outer peripheral side and the region R2 having the width W2 on the inner peripheral side, and the height from the bottom surface of each surface is the height H1 in the region R1. The region R2 has a height H2 and satisfies the relationship of H1> H2. The metal frame 24 is disposed in a state where the surface of the region R <b> 1 is in close contact with the bottom surface of the gas seal member 27. When the adhesion between the metal frame 24 and the gas seal member 27 is impaired, the gas seal performance is deteriorated, so that it is necessary to secure the width W1 of the region R1 to some extent. FIG. 9A corresponds to a cross-sectional structure of a portion where the notch of the opening 30 of the gas seal member 27 is not formed.

Further, the step structure S of the metal frame 24 is formed so that the metal separator 25 is integrally welded. The welding connection between the metal frame 24 and the metal separator 25 is performed in a state in which the surface of the region R2 and the bottom surface of the metal separator 25 are in contact with each other in a welding process described later. As a result of welding, a welding projection P is formed at a predetermined position on the surface of the metal separator 25 on the region R2 by heating during the welding process. This weld projection P is formed over the entire circumference of the band-shaped region R2. As shown in FIG. 9A, the apex of the welding projection P on the metal separator 25 does not reach the height of the region R1 of the metal frame 24. In other words, the thickness T of the metal separator 25 and the height Hp of the welding projection P satisfy the relationship of the following expression (1) with respect to H1-H2 that is the height of the step structure S.
H1-H2> T + Hp (1)

  Here, FIG. 9B shows a cross-sectional structure when the step structure S is not provided in the metal frame 24 as a comparative example with respect to FIG. 9A. In the comparative example of FIG. 9B, the metal frame 24 is not divided into the regions R1 and R2, and the metal separator 25 is welded to the flat surface of the metal frame 24, and the same welding protrusion as in FIG. 9A. The portion P is formed, and the gas seal member 27 is arranged on the upper portion. In the case of this comparative example, since the gas seal member 27 is disposed in contact with the weld projection P, it is difficult to maintain the adhesion as shown in FIG. For this reason, in the comparative example of FIG. 9B, the oxidant gas leaks from the air flow path Ap through the space between the gas seal member 27 and the metal separator 25, and deterioration of gas leakage is unavoidable. On the other hand, if the structure of FIG. 9 (A) is adopted, as long as the expression (1) is satisfied, the welding projection P formed by welding joining is kept in a state of not contacting the bottom surface of the upper gas seal member 27. Therefore, it is possible to ensure good gas leakage without impairing the adhesion between the metal frame 24 and the gas seal member 27.

  On the other hand, in addition to the above structure, the gas seal member 27 is disposed above the step structure S so that the inner peripheral side of the gas seal member 27 protrudes. As described above, the opening 30 of the gas seal member 27 is smaller in size than the opening 33 (FIG. 7) of the metal separator 25. The upper portion is covered with the gas seal member 27 while maintaining a non-contact state with the gas seal member 27 including P. However, the structure as shown in FIG. 9A is not provided immediately below the notch of the opening 30 of the gas seal member 27. With such a structure, even if the flexible metal separator 25 bends upward, the upper gas seal member 27 acts to restrict the deformation of the metal separator 25.

In one embodiment of the unit cell 3 adopting the structure of FIG. 9A, an example of dimensional conditions related to the step structure S will be given below.
H1 = 2mm
H2 = 1.5mm
W1 = 50mm
W2 = 3mm
T = 0.1mm

  Moreover, about the welding projection part P formed at the time of joining, about Hp = 0.05mm is assumed, for example. Therefore, according to the dimensional condition, T + Hp = 0.15 mm with respect to H1−H2 = 0.5 mm. Therefore, a sufficient margin is provided between the weld projection P and the bottom surface of the gas seal member 27 in the step structure S. Can be secured. In FIG. 9A, for easy understanding, the size (H1-H2, W2) of the portion of the stepped structure S is shown enlarged from the actually assumed dimensional condition.

  As described above, considering the normal dimensions of the weld projection P, the height H1-H2 of the step structure S (predetermined height of the present invention) is a value obtained by adding 0.1 mm to the thickness T of the metal separator 25. It is desirable to set it above. This is because when the value of H1−H2 is smaller than 0.1 mm, a margin with respect to the height Hp of the weld projection P cannot be obtained. The thickness T of the metal separator 25 is desirably set within a range of 50 μm to 100 μm (0.1 mm). This is because when the thickness T of the metal separator 25 is too large, sufficient flexibility cannot be secured, and when the thickness T of the metal separator 25 is too small, the strength becomes insufficient.

  Next, of the manufacturing steps of the unit cell 3 according to the present embodiment, steps relating to a characteristic structure will be described with reference to FIG. First, a metal separator 25 having a planar structure shown in FIG. 7 is manufactured by punching a thin metal plate by a known method. Further, the metal frame 24 having the structure shown in FIG. 6 is manufactured by punching a metal plate material by a known method. At this time, a step structure S shown in FIG. 6B is formed on the inner peripheral side of the metal frame 24.

  Next, as shown in FIG. 10A, the metal separator 25 is positioned with respect to the surface of the region R2 of the metal frame 24 while aligning the metal separator 25 with the metal frame 24. . In this state, the metal frame 24 and the metal separator 25 are integrally welded by irradiating the outer edge portion of the metal separator 25 with laser light from above using, for example, a fiber laser welding machine. When the welding joining is completed, a welding projection P shown in FIG. 9A is formed on the surface of the metal separator 25 at the top of the region R2.

  Next, a fuel electrode green sheet to be a support base layer is formed by a well-known technique, a solid electrolyte green sheet is formed, and a laminate of the solid electrolyte green sheet is formed on the upper layer of the fuel electrode green sheet. Subsequently, the obtained laminate is processed into a predetermined rectangular shape and then fired to obtain a sintered body including the fuel electrode layer 11 and the solid electrolyte layer 12. Subsequently, the cell body 10 having the planar structure of FIG. 8 is produced by forming the air electrode layer 13 in a predetermined position on the upper layer of the obtained sintered body.

  Next, as shown in FIG. 10B, a brazing material is applied to the bottom surface of the metal separator 25, and a brazing material is applied to the upper surface of the outer edge portion of the solid electrolyte layer 12 of the cell body 10. As the brazing material, for example, an Ag-based brazing material containing Ag as a main component and some Pd is used. In this state, as shown in FIG. 10C, the cell body 10 is integrated with the metal separator 25 by heating the brazing material while aligning the metal separator 25 and the cell body 10. The unit cell 3 can be obtained by incorporating the portion including the metal frame 24, the metal separator 25, and the cell body 10 obtained as described above.

  The contents of the present invention have been specifically described above based on the present embodiment, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. For example, the material, shape, dimensional conditions, and the like of the metal frame 24, the metal separator 25, and the gas seal member 27 can be variously set as long as the object of the present invention can be achieved. In addition, when the metal frame 24 and the metal separator 25 are welded and joined, the laser device is not limited to a fiber laser welding machine or the like, and other methods may be adopted. Further, each layer constituting the cell body 10 is not limited to the fuel electrode layer 11, the solid electrolyte layer 12, and the air electrode layer 13, and may include functional layers having various roles. In this case, the layer serving as the support base in the cell body 10 is not limited to the fuel electrode layer 11 and may be another layer. Regarding the other points, the contents of the present invention are not limited by the above embodiments, and can be appropriately changed as long as the effects of the present invention can be obtained. For example, the structure, shape, material, formation method, and the like of each constituent member in the unit cell 3 can be appropriately changed as long as the effects of the present invention can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Solid oxide fuel cell 2 ... Fuel cell stack 3 ... Unit cell (fuel cell)
DESCRIPTION OF SYMBOLS 10 ... Cell main body 11 ... Fuel electrode layer 12 ... Solid electrolyte layer 13 ... Air electrode layer 20, 21 ... Interconnector 22 ... Fuel electrode side collector 23 ... Air electrode side collector 24 ... Metal frame 25 ... Metal separator 26 27 ... Gas seal members B1 to B8 ... Bolt N ... Nut Ain ... Air introduction pipe Aout ... Air discharge pipe Ap ... Air flow path Fin ... Fuel gas introduction pipe Fout ... Fuel gas discharge pipe Fp ... Fuel gas flow path P ... Welding Projection S ... Step structure

Claims (8)

A solid oxide comprising a fuel electrode in contact with a fuel gas, an air electrode in contact with an oxidant gas, and a solid electrolyte layer in which the fuel electrode is disposed on one side and the air electrode is disposed on the other side In fuel cell,
A frame having a step structure that is divided into a first region on the outer peripheral side and a second region on the inner peripheral side, and the surface of the second region is formed lower than the surface of the first region by a predetermined height. With a metal frame,
A metal separator that is welded to the surface of the second region of the metal frame and separates the fuel gas flow path and the oxidant gas flow path;
A frame-shaped gas seal member disposed in close contact with the surface of the first region of the metal frame;
With
An inner peripheral side of the gas seal member protrudes above the second region, and the predetermined height is set so that a welded portion of the metal separator is not in contact with the gas seal member. A solid oxide fuel cell.   The metal separator is joined to a cell body in which the fuel electrode, the solid electrolyte layer, and the air electrode are integrally laminated, and the surface of the cell body is exposed from the opening of the metal frame. The solid oxide fuel cell according to claim 1.   Each of the metal frame and the gas seal member has an outer peripheral end portion formed at the same position in plan view, and an inner peripheral side of the gas seal member as compared to an inner peripheral end portion of the metal frame. 3. The solid oxide fuel cell according to claim 1, wherein an end of the solid oxide fuel cell is formed at a position closer to the inner periphery in a plan view. Wherein the predetermined height, the solid oxide according to any one of claims 1 to 3, characterized in that it is set to more than a value obtained by adding 0.1mm to the thickness of the gold Shokuse separator Fuel cell.   5. The solid oxide fuel cell according to claim 4, wherein a thickness of the metal separator is set in a range of 30 μm to 200 μm.   6. The solid oxide fuel cell according to claim 1, wherein the gas seal member is formed using insulating mica. A solid oxide comprising a fuel electrode in contact with a fuel gas, an air electrode in contact with an oxidant gas, and a solid electrolyte layer in which the fuel electrode is disposed on one side and the air electrode is disposed on the other side In the manufacturing method of the fuel cell,
The metal separator that separates the flow path of the fuel gas and the flow path of the oxidant gas is divided into a first region on the outer peripheral side and a second region on the inner peripheral side. A first step of welding and bonding in close contact with the surface of the two regions;
A second step of joining the cell body integrally laminated with the fuel electrode, the solid electrolyte layer, and the air electrode to a metal separator welded to the metal frame;
A third step of closely disposing an insulating frame-shaped gas seal member on the surface of the first region of the metal frame;
The metal frame has a step structure in which a surface of the second region is formed to be lower than a surface of the first region by a predetermined height, and an inner peripheral side of the gas seal member is the second region. And the predetermined height is set so that the welded portion of the metal separator is not in contact with the gas seal member.   8. The method of manufacturing a solid oxide fuel cell according to claim 7, wherein in the first step, the metal separator is joined to the surface of the second region by laser welding.

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