JP2014049325A - Fuel battery cell with separator, manufacturing method thereof, and fuel battery stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery cell with a separator with further improved reliability for jointing a fuel battery cell and a separator, a manufacturing method thereof, and a fuel battery stack.SOLUTION: A fuel battery cell with a separator comprises: a fuel battery cell body on which an air electrode 55 is arranged on a single face side across a solid electrolyte layer 56, and a fuel electrode 57 is arranged on a face side opposite to the single face side; and a frame-like metallic separator 53 mounted to the fuel battery cell body via a jointing part 61 constituted of a solder material containing Ag, and having an opening 58. A sealing part 62 having a sealing material containing glass is provided nearer the opening than the solder material between the metallic separator and the fuel battery cell body.

Description

  The present invention relates to a fuel cell with a separator, a method for manufacturing the same, and a fuel cell stack.

  A solid oxide fuel cell using a solid oxide as an electrolyte (hereinafter also referred to as “SOFC” or simply “fuel cell”) is known. The SOFC has, for example, a stack (fuel cell stack) in which a large number of fuel cells each having a fuel electrode and an air electrode are stacked on each surface of a plate-like solid electrolyte layer. Electric power is generated by supplying a fuel gas (for example, hydrogen) and an oxidant gas (for example, oxygen in the air) to the fuel electrode and the air electrode, respectively, and causing a chemical reaction through the solid electrolyte layer.

  The fuel battery cell is generally used by being connected to a separator that divides a section in which fuel gas and oxidant gas are present.

  Here, the following technique is disclosed as a technique for joining a fuel cell and a separator. A technique for sealing a separator and a fuel battery cell using a glass-based sealing material is disclosed (see Patent Document 1). In addition, by brazing between SOFC components operating at 600 to 800 ° C. with a brazing material having a specific component for keeping the gas tightness of the fuel gas and the oxidant gas, the hydrogen of the fuel gas and the oxidant gas A technique for preventing oxygen from diffusing and reacting in the brazing material to generate voids is disclosed (see Patent Document 2).

Japanese Patent No. 0346960 JP 2010-207863 A

However, the reliability when the fuel cell and the separator are joined only with glass or a brazing material of a specific component may not always be sufficient. For example, in the joining with only Ag solder of a specific component, the Ag wax portion is disposed at the boundary between the oxidant gas and the fuel gas because of the structure. For this reason, the constituent atoms (oxygen) of the oxidant gas from the oxidant gas side and the constituent atoms (hydrogen) of the fuel gas from the fuel gas side enter the Ag low part and diffuse and react with each other over a long period of use. , There is a possibility that voids (pores) are generated in the Ag brazing material and gas leaks. In addition, in the case of joining only with glass, the joining strength is weak, and stress is generated in the joining portion due to deformation of the component parts when the fuel cell is used, so that the glass may be peeled off or cracked.
An object of the present invention is to provide a fuel cell with a separator, a method for manufacturing the same, and a fuel cell stack, in which the reliability of joining of the fuel cell and the separator is further improved.

1. A fuel cell with a separator according to the present invention includes a fuel cell main body in which an air electrode is disposed on one side of a solid electrolyte layer and a fuel electrode is disposed on a surface opposite to the one side, and a brazing electrode containing Ag. A separator-equipped fuel cell comprising: a frame-shaped metal separator attached to the fuel cell body through a joint made of a material and having an opening; A sealing portion having a sealing material containing glass is provided between the metallic separator on the opening side and the fuel cell body.

Since the metal separator is joined to the fuel cell body by a joint composed of a brazing material containing Ag, when a stress is applied from the outside, the sealing portion having a sealing material containing glass Deformation is prevented and the possibility of cracking the sealing portion can be reduced.
In addition, since the sealing portion is disposed on the opening side of the joint portion, the joint portion does not directly contact the oxidant gas, so that the movement of the oxidant gas to the joint portion is prevented. As a result, the diffusion of the oxidant gas in the joint can be suppressed, and the generation of voids due to the reaction between hydrogen and oxygen can be prevented.
Further, since the sealing portion is disposed between the plate-shaped metal separator and the fuel cell, the thermal stress acting on the sealing material becomes a shear stress. For this reason, the sealing material is difficult to break, and peeling at the interface between the sealing portion and the metal separator or the fuel battery cell can be suppressed, and the reliability of the sealing portion can be improved.

(2) The joint is composed of a first joint and a second joint located closer to the opening than the first joint, and an oxygen diffusion coefficient in the second joint is the first joint. It may be smaller than the oxygen diffusion coefficient in one junction.

  Between the sealing part and the first joint part, a second joint part having an oxygen diffusion coefficient smaller than that of the first joint part is disposed. As a result, it is possible to limit the diffusion of oxygen to the first joint, prevent the occurrence of voids in the first joint, and improve the reliability of the entire joint.

(3) It is preferable that the said metal separator contains 0.1 mass% or more and 10 mass% or less of Al.
When a metal material (for example, stainless steel) that forms a chromia (chromium oxide) coating on a metal separator is used, the sealing glass is liable to react with chromia, thus reducing the reliability of the sealing portion. When the metal separator contains 0.1% by mass or more of Al, an alumina coating is formed on the surface thereof, and the reliability of the sealing portion and the oxidation resistance of the metal separator are improved. On the other hand, if the metal separator contains more than 10% by mass of Al, the constituent material of the metal separator becomes hard and difficult to process.
More preferably, the metallic separator contains 1.5% by mass or more and 10% by mass or less of Al. Even more preferably, it is preferable that the metallic separator contains 2.0% by mass or more and 10% by mass or less of Al.

(4) The metal separator preferably has a thickness of 0.5 mm or less.
When the metal separator is thicker than 0.5 mm, when a fuel cell stack is formed by stacking a plurality of fuel cell bodies, the stress applied to the fuel cell body is not relieved, and the fuel cell body In other words, the joint and the sealing part for joining the metal separator may crack (damage). When the metal separator has a thickness of 0.5 mm or less, the stress applied to the joint portion and the sealing portion is relieved, and the possibility that the joint portion and the sealing portion are broken is reduced.

(5) You may have a gap | interval between the said junction part and the said sealing part.
Even if the bonding portion and the sealing portion are not in contact with each other, it is possible to reduce the possibility of the sealing portion cracking and to prevent the diffusion of the oxidizing gas in the bonding portion. In addition, even if gas is contained in the gap, the amount is small, and the influence on the reliability of the joint is small.

(6) The melting temperature of the brazing material constituting the joint portion may be higher than the melting temperature of the sealing material.
Even if the melting temperature of the brazing material is higher than the melting temperature of the sealing material, the fuel cell body and the metal separator can be joined and sealed. For example, sealing with a sealing material may be performed after joining with a brazing material. If the difference between the melting temperature of the brazing material and the melting temperature of the sealing material is not large, it is possible to perform bonding and sealing at the same time.

2. A fuel cell stack according to the present invention includes the fuel cell with a separator described above.
By using the fuel cell with a separator described above, the reliability of the entire fuel cell stack is improved.

3. A method for manufacturing a fuel cell with a separator according to the present invention is a method for manufacturing a fuel cell with a separator as described above, wherein the brazing material is disposed in both the metallic separator and the fuel cell body. And a sealing material arranging step of arranging a sealing material containing the glass on at least one of the metal separator and the fuel cell body.

  By arranging the brazing material on both the metallic separator and the fuel cell body, the two brazing materials previously arranged on the metallic separator and the fuel cell body respectively melt and fuse, thereby reducing the contact area. It can be ensured and the bonding strength can be increased.

(1) You may further comprise the joining process which fuse | melts the brazing material arrange | positioned in both the said metal separator and a fuel cell main body, and joins the said metal separator and a fuel cell main body.
By melting the brazing material, the metal separator and the fuel cell body can be joined with high strength.

(2) In the joining step, the brazing material is preferably brazed in the atmosphere. This is because the material used for the air electrode changes its characteristics in a vacuum or a reducing atmosphere.

(3) further comprising a sealing part forming step of melting the sealing material including the glass disposed in at least one of the metal separator and the fuel cell main body to form the sealing part. Also good.
The sealing material can be melted to seal between the metal separator and the fuel cell body.

(4) The joining step and the sealing portion forming step may be performed under the same temperature and the same atmosphere.
Bonding and sealing can be performed simultaneously, which simplifies the manufacturing equipment and improves manufacturing time efficiency.

(5) The sealing material arranging step and the sealing portion forming step may be performed after the joining step.
By performing bonding and sealing separately, it is possible to combine various brazing materials and sealing materials. In order to perform bonding and sealing simultaneously, it is preferable that the bonding temperature of the brazing material and the melting temperature of the sealing material are close to each other to some extent, and the brazing material and the sealing material that can be used are limited.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell with a separator which improved the reliability of joining of a fuel cell and a separator, its manufacturing method, and a fuel cell stack can be provided.

1 is a perspective view showing a solid oxide fuel cell 10. FIG. 1 is a schematic cross-sectional view of a solid oxide fuel cell 10. FIG. 3 is a cross-sectional view of a fuel cell 40. FIG. It is a disassembled perspective view showing the state which decomposed | disassembled the fuel cell main body 44 and the metal separator 53 (fuel cell with a separator). It is a flowchart showing the manufacturing process of a fuel cell with a separator. It is sectional drawing showing the state of the fuel cell with a separator in manufacture. It is sectional drawing showing the state of the fuel cell with a separator in manufacture. It is sectional drawing showing the state of the fuel cell with a separator in manufacture. It is sectional drawing showing the state of the fuel cell with a separator in manufacture. It is sectional drawing showing the state of the fuel cell with a separator in manufacture. It is a flowchart showing the manufacturing process of a fuel cell with a separator. It is sectional drawing showing the state of the fuel cell with a separator in manufacture. It is sectional drawing showing the state of the fuel cell with a separator in manufacture. It is sectional drawing showing the state of the fuel cell with a separator in manufacture. It is sectional drawing showing the state of the fuel cell with a separator in manufacture. It is sectional drawing of the fuel cell 40a. It is a disassembled perspective view showing the state which decomposed | disassembled the fuel cell main body 44 and the metal separator 53 (fuel cell with a separator). It is sectional drawing of the fuel battery cell 40b. It is a disassembled perspective view showing the state which decomposed | disassembled the fuel cell main body 44 and the metal separator 53 (fuel cell with a separator).

  Hereinafter, a solid oxide fuel cell according to the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a perspective view showing a solid oxide fuel cell (fuel cell stack) 10 according to a first embodiment of the present invention. The solid oxide fuel cell 10 generates power by receiving supply of a fuel gas (for example, hydrogen) and an oxidant gas (for example, air (specifically, oxygen in the air)).

  In the solid oxide fuel cell 10, end plates 11 and 12, fuel cells 40 (1) to 40 (4) are laminated, bolts 21, 22 (22a, 22b), 23 (23a, 23b) and nuts 35. It is fixed with.

FIG. 2 is a schematic cross-sectional view of the solid oxide fuel cell 10.
The solid oxide fuel cell 10 is a fuel cell stack configured by stacking fuel cells 40 (1) to 40 (4). Here, for the sake of clarity, four fuel cells 40 (1) to 40 (4) are stacked, but in general, about 20 to 60 fuel cells 40 are often stacked. .

The end plates 11 and 12 and the fuel cells 40 (1) to 40 (4) have through holes 31 and 32 (32a and 32b) corresponding to the bolts 21 and 22 (22a and 22b) and 23 (23a and 23b), 33 (33a, 33b).
The end plates 11 and 12 are holding plates that press and hold the stacked fuel battery cells 40 (1) to 40 (4), and output current from the fuel battery cells 40 (1) to 40 (4). It is also a terminal.

  FIG. 3 is a cross-sectional view of the fuel battery cell 40. FIG. 4 is an exploded perspective view showing a state in which the fuel cell body 44 and the metal separator 53 (fuel cell with separator) are disassembled.

  As shown in FIG. 3, the fuel cell 40 includes a metal separator 53 and a fuel cell main body 44, and includes interconnectors 41 and 45, a current collector 42, and a frame portion 43.

The fuel cell main body 44 includes a solid electrolyte layer 56 sandwiched between an air electrode (also referred to as a cathode or an air electrode layer) 55 and a fuel electrode (also referred to as an anode or a fuel electrode layer) 57. An air electrode 55 and a fuel electrode 57 are arranged on the oxidant gas flow channel 47 side and the fuel gas flow channel 48 side of the solid electrolyte layer 56, respectively.
In the present embodiment, all of the solid electrolyte layer 56, the air electrode 55, and the fuel electrode 57 are formed in a plate shape, but each may be formed in a cylindrical shape.

  As the air electrode 55, perovskite oxides (for example, LSCF (lanthanum strontium cobalt iron oxide), LSM (lanthanum strontium manganese oxide), various noble metals, and cermets of noble metals and ceramics can be used.

  For the solid electrolyte layer 56, materials such as YSZ (yttria stabilized zirconia), ScSZ (scandia stabilized zirconia), SDC (samarium doped ceria), GDC (gadolinium doped ceria), and perovskite oxide can be used.

  The fuel electrode 57 is preferably a metal, and Ni, Ni-ceramic cermets or Ni-based alloys can be used.

  The interconnectors 41 and 45 are plates having conductivity (for example, a metal such as stainless steel) that can secure conduction between the fuel cell main bodies 44 and prevent gas mixing between the fuel cell main bodies 44. Shaped member.

  In addition, only one interconnector (41 or 45) is disposed between the fuel cell main bodies 44 (one interconnector is shared between two fuel cell main bodies 44 connected in series). Because). Further, in each of the uppermost and lowermost fuel cell main bodies 44, conductive end plates 11 and 12 are disposed in place of the interconnectors 41 and 45, respectively.

  The current collector 42 is for ensuring electrical connection between the air electrode 55 of the fuel cell main body 44 and the interconnector 41, and is made of a metal material such as a nickel alloy, for example. Further, the current collector 42 may have elasticity.

  The frame portion 43 has an opening 46 through which an oxidant gas and a fuel gas flow. The opening 46 is kept airtight and is divided into an oxidant gas passage 47 through which an oxidant gas flows and a fuel gas passage 48 through which fuel gas flows. Further, the frame portion 43 of this embodiment includes an air electrode frame 51, an insulating frame 52, a metal separator 53, and a fuel electrode frame 54.

  The air electrode frame 51 is a metal frame disposed on the air electrode 55 side, and has an opening 46 at the center. An oxidant gas flow path 47 is defined by the opening 46.

The insulating frame 52 is a frame that electrically insulates between the interconnectors 41 and 45. For example, ceramics such as Al ₂ O ₃ , mica, vermiculite, and the like can be used, and an opening 46 is provided at the center. An oxidant gas flow path 47 is defined by the opening 46. Specifically, the insulating frame 52 is disposed between the interconnectors 41 and 45 such that one surface contacts the air electrode frame 51 and the other surface contacts the metal separator 53. As a result, the interconnectors 41 and 45 are electrically insulated by the insulating frame 52.

  The metal separator 53 is a frame-shaped metal thin plate (for example, thickness: 0.1 mm) having an opening 58, is attached to the solid electrolyte layer 56 of the fuel cell main body 44, and has an oxidant gas. It is a metal frame that prevents mixing with fuel gas. The metal separator 53 divides the space in the opening 46 of the frame portion 43 into an oxidant gas flow path 47 and a fuel gas flow path 48, thereby preventing mixing of the oxidant gas and the fuel gas.

  An opening 58 is formed in the metal separator 53 by a through-hole penetrating between the upper surface and the lower surface of the metal separator 53, and the air electrode 55 of the fuel cell main body 44 is disposed in the opening 58. . The fuel cell main body 44 to which the metallic separator 53 is joined is referred to as a “fuel cell with separator”. Details of this will be described later.

  Like the insulating frame 52, the fuel electrode frame 54 is an insulating frame disposed on the fuel electrode 57 side, and has an opening 46 in the center. A fuel gas flow path 48 is defined by the opening 46.

  Bolts 21, 22 (22a, 22b), 23 (23a, 23b) are inserted into the air electrode frame 51, the insulating frame 52, the metal separator 53, and the fuel electrode frame 54, or an oxidant gas or a fuel gas is inserted. The through holes 31, 32 (32a, 32b), 33 (33a, 33b) that circulate are provided in the respective peripheral portions.

(Details of fuel cell with separator)
In the present embodiment, a joining portion 61 and a sealing portion 62 are disposed between the fuel cell main body 44 and the metal separator 53 to constitute the separator-equipped fuel cell 50. Along the opening 58, the lower surface of the metallic separator 53 and the upper surface of the solid electrolyte layer 56 are joined by the joining portion 61 and sealed by the sealing portion 62.

The metal separator 53 is made of a metal material containing iron (Fe) as a main component. This metal material preferably contains 0.1 mass% or more and 10 mass% or less (for example, 3 mass%) of Al.
The metal separator has an alumina film formed on the surface thereof, improving oxidation resistance and excellent workability.

The metal separator 53 has a thickness of 0.1 mm, for example.
The metal separator 53 is applied to the joint 61 and the sealing portion 62 that connect the fuel cell body 44 and the metal separator 53 when the solid oxide fuel cell 10 (fuel cell stack) is formed. The stress is relaxed, and the possibility of occurrence of a problem such as damage (cracking) of the joint portion 61 or the sealing portion 62 is reduced.

  The joining portion 61 is made of a brazing material containing Ag, and is disposed over the entire circumference along the opening 58 to join the fuel cell body 44 and the metal separator 53. The joining portion 61 (Ag solder) has, for example, a width of 2 to 6 mm and a thickness of 10 to 80 μm.

As the material of the joining portion 61, various brazing materials mainly composed of Ag can be employed. For example, as a brazing material, a mixture of Ag and an oxide, for example, Ag-Al ₂ O ₃ (a mixture of Ag and Al ₂ O ₃ (alumina)) can be used. Examples of the mixture of Ag and oxide include Ag—CuO, Ag—TiO ₂ , Ag—Cr ₂ O ₃ , and Ag—SiO ₂ . Further, an alloy of Ag and another metal (for example, any one of Ag—Ge—Cr, Ag—Ti, and Ag—Al) can be used as the brazing material.

  The brazing material containing Ag (Ag brazing) is not easily oxidized at the brazing temperature even in an air atmosphere. For this reason, the fuel cell main body 44 and the metal separator 53 can be joined in an air atmosphere using Ag wax, which is preferable in terms of process efficiency.

The sealing portion 62 is disposed on the opening 58 side (inner peripheral side) of the joining portion 61 along the opening 58 over the entire circumference, and the oxidant gas in the opening 58 of the metallic separator 53 In order to prevent mixing with the fuel gas outside the opening 58, the space between the fuel cell main body 44 and the metal separator 53 is sealed. Since the sealing portion 62 is disposed on the opening 58 side of the joint portion 61, the joint portion 61 is not brought into contact with the oxidant gas, and oxygen from the oxidant gas flow path 47 side to the joint portion 61 is eliminated. Movement is prevented. As a result, it is possible to prevent a gas leak from occurring in the junction 61 due to the reaction between hydrogen and oxygen. Furthermore, since the sealing portion 62 is disposed between the metallic separator 53 and the fuel cell main body 44, the thermal stress acting on the sealing portion 62 is not tensile stress but shear stress. For this reason, the sealing material becomes difficult to break, and peeling at the interface between the sealing portion 62 and the metal separator 53 or the fuel cell main body 44 can be suppressed, and the reliability of the sealing portion 62 can be improved.
The sealing part 62 has a width of 1 to 4 mm and a thickness of 80 to 200 μm, for example.

  For the sealing portion 62, a sealing material containing glass, specifically, glass, glass ceramics (crystallized glass), or a composite of glass and ceramics can be used. As an example, glass manufactured by SCHOTT: G018-311 can be used.

(Manufacture of fuel cell with separator)
Hereinafter, a method for manufacturing a fuel cell with a separator (a fuel cell main body 44 to which a metallic separator 53 is joined) will be described. Here, two manufacturing methods (manufacturing methods A and B) will be described.

In any of the manufacturing methods, first, for example, a metal plate 53 having an opening 58 was manufactured by punching a plate material made of SUH21 (18Cr-3Al (a kind of Al-containing ferritic stainless steel)). In addition, a sheet of the solid electrolyte layer 56 was attached to one surface of the green sheet of the fuel electrode 57 to form a laminate, and the laminate was fired once. Thereafter, the material of the air electrode 55 was printed and fired to prepare the fuel cell main body 44.

1. Manufacturing method A
As shown below, in the manufacturing method A, joining (formation of the joining part 61) and formation of the sealing part 62 are performed simultaneously. FIG. 5 is a flowchart showing the manufacturing process of the separator-equipped fuel cell in the manufacturing method A. 6A to 6E are cross-sectional views showing states of the separator-equipped fuel cell being manufactured by the manufacturing method A. FIG.

(1) Arrangement of brazing materials 611 and 612 (step S11, FIG. 6A)
The brazing materials 611 and 612 are disposed on the fuel cell main body 44 and the metal separator 53, respectively. For example, a brazing material containing paste-like Ag is printed in a predetermined shape on the upper surface of the solid electrolyte layer 56 of the fuel cell body 44 and the lower surface of the metal separator 53, so that the fuel cell body 44 and the metal separator 53 respectively. The brazing materials 611 and 612 are disposed on the surface. As a method for arranging the brazing materials 611 and 612, in addition to the above, a dispenser may be used.
For example, the brazing materials 611 and 612 have a width of 2 to 6 mm and a thickness of 10 to 80 μm.

  The two brazing members 611 and 612 previously disposed in the fuel cell main body 44 and the metal separator 53 are melted and fused, so that a contact area can be ensured and the joining strength of the joining portion 61 can be increased.

  When the brazing material is disposed on only one of the fuel cell body 44 and the metal separator 53, the brazing material melts, wets the other surface, and then solidifies, so that the fuel cell body 44 and the metal separator 53 are solidified. The other of the two and the brazing material are combined. Thus, when the brazing material is melted and then comes into contact with the fuel cell body 44 or the metal separator 53, the contact area tends to be small, and it may be difficult to ensure the bonding strength. Since the wettability of the molten brazing material to the fuel cell body 44 and the metal separator 53 is not always good, the brazing material is applied to both the fuel cell body 44 and the metal separator 53 before joining. By arrange | positioning, the joining strength of the junction part 61 can be improved.

(2) Arrangement of sealing material 621 (Step S12, FIG. 6B, FIG. 6D, FIG. 6E)
A sealing material 621 is disposed on the opening 58 side or the air electrode 55 side of at least one of the fuel cell main body 44 and the metal separator 53. For example, the sealing material 621 is disposed on at least one of the fuel cell main body 44 and the metal separator 53 by printing a paste-like sealing material in a predetermined shape. In addition, as a method for arranging the sealing material, a dispenser may be used in addition to the above.
The sealing material 621 has, for example, a width of 1 to 4 mm and a thickness of 80 to 200 μm.

  6B, FIG. 6D, and FIG. 6E each show a form in which sealing materials 621 and 622 are disposed only on the fuel cell main body 44, only the metal separator 53, and both the fuel cell main body 44 and the metal separator 53. . In all the forms, the sealing materials 621 and 622 are disposed on the opening 58 side or the air electrode 55 side of the joint portion (brazing material) 61.

  As described above, the brazing material is preferably disposed on both the fuel cell body 44 and the metal separator 53, but the sealing material is disposed on one of the fuel cell body 44 and the metal separator 53. That's fine. This is due to the difference in wettability when the brazing material and the sealing material are melted. Since the sealing material containing glass has better wettability with respect to the fuel cell main body 44 and the metal separator 53 than the brazing material, the sealing material may be disposed on both of them.

  The metallic separator 53 is made of a material that forms an oxide film (oxide (alumina)) in high-temperature air, and the solid electrolyte layer 56 is also made of an oxide. For this reason, the metal separator 53 and the solid electrolyte layer 56 have better wettability with respect to the sealing material (glass (oxide)) than the brazing material (metal).

  In this embodiment, (1) the placement of the brazing material and (2) the placement of the sealing material are performed in this order, but the reverse or the placement of the brazing material and the sealing material may be performed simultaneously. .

(3) Joining (formation of the joining part 61) and formation of the sealing part 62 (step S13, FIG. 6C)
The brazing materials 611 and 612 were melted, and the fuel cell body 44 and the metal separator 53 were joined (formation of the joining portion 61). At the same time, the sealing material 621 was melted to form the sealing portion 62. By bringing the fuel cell main body 44 in which the brazing materials 611 and 612 and the sealing material 621 are disposed into contact with the metal separator 53 and heating in the air atmosphere at, for example, 850 to 1100 ° C., the brazing material 611, 612 and the sealing material 621 were melted, and the joint portion and the sealing portion were simultaneously formed.

  As described above, the two brazing members 611 and 612 arranged in advance in the fuel cell main body 44 and the metal separator 53 are melted and fused to ensure a contact area and improve the bonding strength. Can do.

  At this time, since the brazing materials 611 and 612 and the sealing material 621 are disposed adjacent to each other, the bonding (formation of the joining portion 61) and the formation of the sealing portion 62 are performed under substantially the same temperature and the same atmosphere. Will be done.

  At the time of joining, a load is applied from above and below the fuel cell body 44 and the metal separator 53 so that the melted brazing material is in close contact with the fuel cell body 44 and the metal separator 53. As a result, a load can be applied to the adjacent sealing material 621 from above and below, and sealing can be performed without a gap.

Since the brazing material contains Ag and is not easily oxidized at the brazing temperature even in the air atmosphere, brazing (bonding) in the air atmosphere is possible, and the fuel in forming the joint portion 61 and the sealing portion 62 (step S13). The performance of the battery cell main body 44 (particularly, the air electrode 55) is deteriorated. Specifically, the crystal structure of the air electrode 55 (for example, LSCF (lanthanum strontium cobalt iron oxide)) of the fuel battery cell main body 44 is caused by the change. Electrode performance can be prevented.
Furthermore, since it is not necessary to use an inert gas such as Ar as the atmosphere at the time of joining in order to prevent the performance deterioration of the fuel cell main body 44, the efficiency of the device or process can be reduced without complicating the device or process. Can be realized.

  As described above, in the manufacturing method A, the bonding (formation of the joining part 61) and the formation of the sealing part 62 are performed under the same temperature and the same atmosphere, thereby simplifying the production apparatus and shortening the production time. Thus, it is possible to efficiently manufacture a fuel cell with a separator.

2. Manufacturing method B
In the manufacturing method B, joining (formation of the joining part 61) and formation of the sealing part 62 are performed separately. FIG. 7 is a flowchart showing the manufacturing process of the separator-equipped fuel cell in the manufacturing method B. 8A to 8D are cross-sectional views showing states of the separator-equipped fuel cell being manufactured by the manufacturing method B. FIG.

(1) Arrangement of brazing materials 611 and 612 (step S21, FIG. 8A)
The brazing materials 611 and 612 are disposed on the fuel cell main body 44 and the metal separator 53, respectively. Since this process is the same as step S11 of manufacturing method A, detailed description thereof is omitted.

(2) Joining (formation of joined part 61) (step S22, FIG. 8B)
The brazing materials 611 and 612 are melted, and the fuel cell main body 44 and the metal separator 53 are joined (formation of the joining portion 61). The fuel cell main body 44 on which the brazing materials 611 and 612 are disposed and the metal separator 53 are brought into contact with each other and heated at 850 to 1100 ° C., for example, so that the brazing materials 611 and 612 are melted and joined.

  As described above, the two brazing members 611 and 612 previously disposed in the fuel cell main body 44 and the metal separator 53 are melted and fused, so that a contact area can be ensured and the bonding strength can be increased. .

(3) Arrangement of sealing material 621 (step S23, FIG. 8C)
A sealing material 621 is disposed on at least one of the fuel cell main body 44 and the metal separator 53. For example, the sealing material 621 can be disposed on at least one of the fuel cell main body 44 and the metal separator 53 by printing a paste containing the sealing material. As described above, since the sealant generally has good wettability, it can be disposed on one of the fuel cell main body 44 and the metal separator 53.

(4) Formation of the sealing part 62 (step S24, FIG. 8D)
The sealing material 621 is melted to form the sealing portion 62. By heating the fuel cell body 44 and the metal separator 53 joined at the joining portion 61 and having the sealing material 621 disposed at 850 to 1100 ° C., for example, the sealing material 621 is melted and sealed. Done.

  As described above, in the manufacturing method B, bonding and sealing are performed separately. By performing bonding and sealing separately, various combinations of brazing material and sealing material are possible.

  In order to perform bonding and sealing simultaneously, it is preferable that the bonding temperature of the brazing material and the melting temperature of the sealing material are close to each other to some extent, and the brazing material and the sealing material that can be used are limited. Generally, the melting point of the brazing material is higher than the melting point of the sealing material (glass). If the bonding temperature of the brazing material and the melting temperature of the sealing material are different, if the bonding and sealing are performed at the same time, sealing may occur due to deterioration of the sealing material component or thinning due to evaporation.

(Method for producing solid oxide fuel cell (fuel cell stack) 10)
For example, a plate material made of SUH21 is punched into a predetermined shape, and end plates 11 and 12, interconnectors 41 and 45, an air electrode frame 51, and a fuel electrode frame 54 are manufactured. On the other hand, an insulating frame 52 was manufactured by processing a plate material made of mica.

  On the air electrode 55 side of the fuel cell body 44 of the separator-equipped fuel cell 50 produced by either the manufacturing method A or B described above, an insulating frame 52, an air electrode frame 51, and an interface are disposed on a metal separator 53. The fuel cell 40 was manufactured by arranging the fuel electrode frame 54 and the interconnector 45 in this order on the fuel electrode 57 side in the order of the connector 41.

  A plurality of fuel cells 40 are stacked, end plates 11 and 12 are arranged on the uppermost layer and the lowermost layer, and the plurality of fuel cells 40 are sandwiched between the end plates 11 and 12 by bolts 21 to 23 and nuts 35. The fuel cell stack 10 was prepared by fixing.

(Modification of the first embodiment)
A modification of the first embodiment will be described. FIG. 9 is a cross-sectional view of a fuel cell 40a according to a modification of the first embodiment. FIG. 10 is an exploded perspective view showing a state in which the fuel cell body 44 and the metal separator 53 (separator-equipped fuel cell 50) according to a modification of the first embodiment are disassembled.

  In the fuel cell 40a, there is a gap between the joint portion 61 and the sealing portion 62. Thus, even if the joining part 61 and the sealing part 62 are not in contact with each other, it is possible to reduce the possibility of the sealing part 62 being broken and to prevent the oxidant gas from diffusing in the joining part 61.

  In the fuel cells 40 and 40a, the joint 61 and the sealing portion 62 are in contact with each other over the entire circumference of the opening 58 or have a gap. As an intermediate aspect thereof, the joining portion 61 and the sealing portion 62 are in contact with each other around the opening 58, and the joining portion 61 and the sealing portion 62 are not in contact with each other around the opening 58. Is also possible.

The separator-attached fuel battery cell according to the modification of the first embodiment can be manufactured using any one of the manufacturing methods A and B, as in the first embodiment.
In that case, the sealing material is arranged with a certain gap with respect to the brazing material, and the fuel cell main body 44 and the metallic separator 53 are joined.

(Second Embodiment)
A second embodiment will be described. FIG. 11 is a cross-sectional view of a fuel battery cell 40b according to the second embodiment. FIG. 12 is an exploded perspective view showing a state in which the fuel cell body 44 and the metal separator 53 (the separator-equipped fuel cell 50) according to the second embodiment are disassembled.

  In the fuel cell 40b, the joint 61 is divided into a joint 61a disposed away from the opening 58 and a joint 61b disposed closer to the opening 58 than the joint 61a. Further, the oxygen diffusion coefficient in the junction 61b is made of a material smaller than the oxygen diffusion coefficient in the junction 61a.

  Between the sealing part 62 and the joining part 61a, a joining part 61b having an oxygen diffusion coefficient smaller than that of the joining part 61a is disposed. That is, even if there is an oxidant gas that has passed through the sealing portion 62, it is possible to suppress the oxidant gas from reaching the joint portion 61a because the oxygen diffusion coefficient at the joint portion 61b is small. As a result, it is possible to suppress the diffusion of oxygen in the joint portion 61a, prevent the occurrence of voids due to oxygen or the like in the joint portion 61a, and improve the reliability of joining the fuel cell 40b and the metal separator 53.

As the material of the joint portion 61a, for example, various brazing materials mainly composed of Ag such as the following materials 1) and 2) can be adopted.
1) Ag brazing material (Ag—Cr ₂ O ₃ brazing material) containing Cr ₂ O ₃ (for example, 1 to 5 wt%)
2) Ag brazing material (Ag-Pd brazing material) containing Pd (for example, 2 to 30% by mass, preferably 3 to 10% by mass)

  The material of the joining part 61b can be appropriately selected according to the material (oxygen diffusion coefficient) of the joining part 61a, and examples thereof include Ni, Pt, and Au. Of these, Ni and Pt are suitable because of their large oxygen diffusion barrier properties (large oxygen diffusion coefficient). In particular, Pt is more suitable as an oxygen diffusion barrier because oxidation does not proceed under the condition of joining an Ag brazing material in the atmosphere.

  The fuel cell with a separator according to the modification of the second embodiment can be manufactured using a method corresponding to the manufacturing methods A and B.

  Specifically, in step S <b> 11 of the manufacturing method A, two types of brazing materials corresponding to the joint portions 61 a and 61 b are disposed on both the fuel cell body 44 and the metal separator 53. Thereafter, the sealing material 621 is disposed (corresponding to step S12) and heated, so that the two kinds of brazing material and the sealing material are melted and can be joined and sealed (corresponding to step S13).

  Further, as a method corresponding to the manufacturing method B, the joining portions 61a and 61b and the sealing portion 62 may be formed sequentially. In this case, it is preferable to arrange these constituent materials and form (heat) the joint portions 61a and 61b and the sealing portion 62 in descending order of the melting points of the constituent materials of the joint portions 61a and 61b and the sealing portion 62. .

(Other embodiments)
Embodiments of the present invention are not limited to the above-described embodiments, and can be expanded and modified. The expanded and modified embodiments are also included in the technical scope of the present invention.

10 Solid oxide fuel cell (fuel cell stack)
11, 12 End plate 21, 22 Bolt 31, 32 Through hole 35 Nut 40, 40, 40a Fuel cell 41, 45 Interconnector 42 Current collector 43 Frame 44 Fuel cell main body 46 Opening 47 Oxidant gas flow path 48 Fuel gas flow path 50 Fuel cell with separator 51 Air electrode frame 52 Insulating frame 53 Metal separator 54 Fuel electrode frame 55 Air electrode 56 Solid electrolyte layer 57 Fuel electrode 58 Openings 61, 61a, 61b Joints 611, 612 Brazing material 62 Sealing part 621,622 Sealing material

Claims (13)

A fuel cell body configured by sandwiching a solid electrolyte layer between an air electrode and a fuel electrode;
A frame-shaped metal separator attached to the fuel cell body through a joint composed of a brazing material containing Ag and having an opening;
A fuel cell with a separator, comprising:
A sealing portion having a sealing material containing glass is provided between the metallic separator on the opening side of the brazing material and the fuel cell body.
A separator-equipped fuel cell. The joint is composed of a first joint and a second joint located on the opening side of the first joint,
The oxygen diffusion coefficient in the second junction is smaller than the oxygen diffusion coefficient in the first junction,
The separator-equipped fuel cell according to claim 1. The metal separator contains 0.1 mass% or more and 10 mass% or less of Al,
The separator-equipped fuel cell according to claim 1 or 2. The metal separator has a thickness of 0.5 mm or less,
The separator-equipped fuel cell according to any one of claims 1 to 3. Having a gap between the joint and the sealing portion;
The fuel cell with a separator according to any one of claims 1 to 4, wherein the fuel cell has a separator. The melting temperature of the brazing material constituting the joint is higher than the melting temperature of the sealing material;
The separator-equipped fuel cell according to any one of claims 1 to 5. A fuel cell with a separator according to any one of claims 1 to 6,
A fuel cell stack comprising: It is a manufacturing method of the fuel cell with a separator of any one of Claims 1 thru | or 7, Comprising:
A brazing material disposing step of disposing the brazing material on both the metal separator and the fuel cell body;
A sealing material disposing step of disposing a sealing material containing the glass on at least one of the metallic separator and the fuel cell body;
Comprising
The manufacturing method of the fuel cell with a separator characterized by the above-mentioned. It is a manufacturing method of the fuel cell with a separator of Claim 8, Comprising:
A fuel cell with a separator, further comprising a joining step of melting the brazing material disposed in both of the metal separator and the fuel cell body and joining the metal separator and the fuel cell body. Cell manufacturing method. It is a manufacturing method of the fuel cell with a separator according to claim 9,
In the joining step, the brazing material is melted in the atmosphere.
The manufacturing method of the fuel cell with a separator characterized by the above-mentioned. It is a manufacturing method of the fuel cell with a separator according to claim 10,
A sealing part forming step for melting the sealing material including the glass disposed in at least one of the metal separator and the fuel cell body, and forming the sealing part;
Further comprising
The manufacturing method of the fuel cell with a separator characterized by the above-mentioned. It is a manufacturing method of the fuel cell with a separator according to claim 11,
The method for manufacturing a fuel cell with a separator, wherein the joining step and the sealing portion forming step are performed simultaneously. It is a manufacturing method of the fuel cell with a separator according to claim 11,
The method for producing a fuel cell with a separator, wherein the sealing material arranging step and the sealing portion forming step are performed after the joining step.

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