JP2005174658A - Solid electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superior solid electrolyte fuel cell in which a gas seal part that is superior in joining strength can be formed, and which is tough against thermal stress and which can be manufactured with a superior yield by suppressing sagging of a cement. <P>SOLUTION: The fuel cell is provided with a power generation layer 2, and laminating members 31, 32, 33 and laminated members 21 are joined with the cement in which metal is the main component and a gas seal part 10 is formed between both members and basin parts 311, 321, 331 on which the joining agent may be collected are installed at least at the laminating member among the laminating members and the laminated members. It is preferable that the laminating members are composed of a heat-resistant metal. Furthermore, it is preferable that the basin part is formed by a chamfer part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a solid oxide fuel cell. More specifically, the present invention is capable of forming a gas seal portion having excellent bonding strength, is strong against thermal stress, and can be manufactured with high yield by suppressing sagging of the bonding agent. The present invention relates to a solid oxide fuel cell.

  2. Description of the Related Art Conventionally, a flat plate type solid oxide fuel cell (hereinafter also referred to as SOFC) is used as a structure (hereinafter also referred to as a stack) in which a plurality of single cells are stacked. As a general structure of a flat plate type SOFC stack, for example, a solid electrolyte plate made of yttria-stabilized zirconia (YSZ), a fuel electrode made of nickel and YSZ, a perovskite composite oxide {for example, lanthanum manganese knight (LSM) ) Etc.} is formed by laminating a single cell having a power generation layer formed with an air electrode made of lanthanum chromite complex oxide or a separator made of a refractory metal. The solid electrolyte plate and the separator are hermetically sealed with a glassy sealing material.

  In recent years, research has been actively conducted to reduce the internal resistance by forming a solid electrolyte plate such as YSZ as much as possible to reduce the internal resistance and operate the SOFC at a relatively low temperature of 800 ° C. or lower. It is attracting attention. In particular, if an inexpensive stainless material can be applied, the cost can be greatly reduced. However, as long as the sealing material is made of glass, it is not possible to improve the bonding reliability.

In order to solve this problem, the present inventors have proposed an SOFC in which a gas seal portion is formed using, for example, a bonding agent mainly composed of Ag and Pd (for example, Patent Documents). 1 and Patent Document 2).
However, in the above-described joint structure, although a gas seal portion having excellent joint strength has been achieved, the use of a conductive metallic joint agent, depending on the shape of the joint surface and the coating amount of the joint agent. In such a case, there is a possibility that the sagging of the bonding agent may occur, resulting in a short circuit failure. As a result, the yield may be reduced.

Japanese Patent Application No. 2002-377846 Japanese Patent Application No. 2002-377848

  As described above, the present invention solves the problems shown in the above prior art, and can form a gas seal portion with excellent bonding strength, is strong against thermal stress, and suppresses sagging of the bonding agent and is manufactured with high yield. An object of the present invention is to provide a solid oxide fuel cell that can be used.

The present invention is as follows.
[1] A power generation layer having a solid electrolyte body, a fuel electrode provided on one surface of the solid electrolyte body, and an air electrode provided on the other surface, and the laminated member and the laminated member are mainly made of metal. In a solid oxide fuel cell formed by bonding with a bonding agent as a component to form a gas seal portion between both members,
A solid oxide fuel cell characterized in that at least a part of the joining edge part of at least one of the laminated member and the laminated member is provided with a reservoir part in which the bonding agent can be accumulated.
[2] The solid oxide fuel cell according to [1], wherein the laminated member is made of a heat-resistant metal.
[3] The solid oxide fuel cell according to the above [2], wherein the pool portion is a chamfered portion.
[4] The solid oxide fuel cell according to [2] or [3], wherein the layered member is made of ceramic, and the layered member is provided with a protruding portion that protrudes from a joint surface of the layered member.
[5] The above [1] to [4], wherein the laminated member is a separator made of a heat-resistant metal for separating the power generation layer and other power generation layers, and the laminated member is the solid electrolyte body. The solid oxide fuel cell according to any one of claims.
[6] The above-mentioned laminated member is a metal frame made of a refractory metal for accommodating the power generation layer, and the laminated member is a ceramic frame made of ceramic for accommodating the power generation layer. The solid oxide fuel cell according to any one of [1] to [4].

According to the solid oxide fuel cell of the present invention, the laminated member and the member to be laminated are joined by the joining agent mainly composed of metal, and the excess joining agent is stored in the reservoir provided in the laminated member. Therefore, a gas seal portion with excellent bonding strength can be formed, and it can be tough against thermal stress. Moreover, generation | occurrence | production of the dripping of a bonding agent can be suppressed, generation | occurrence | production of a short circuit defect can be suppressed effectively, and it can manufacture with a yield.
Moreover, when the said laminated member consists of a heat-resistant metal, the workability of a reservoir part can be improved.
Moreover, when the said reservoir part is formed by the chamfered part, while being able to improve the workability of a reservoir part, the excess joining agent can be more efficiently stored, suppressing the reduction | decrease of a joining area as much as possible.
In addition, when the laminated member is made of ceramic and the laminated member is provided with a protruding portion that protrudes from the bonding surface of the laminated member, the occurrence of short-circuit failure is further suppressed by suppressing the occurrence of dripping of the bonding agent as much as possible. Can be suppressed.
Further, when the laminated member is a separator made of a heat-resistant metal for separating the power generation layer and other power generation layers, and the laminated member is the solid electrolyte body, a so-called self-supporting membrane type solid electrolyte is used. The fuel cell can have a structure that is strong against thermal stress, and can be manufactured with high yield.
Further, the laminated member is a first frame member made of a heat-resistant metal for accommodating the power generation layer, and the laminated member is a second frame member made of ceramic for accommodating the power generation layer. The so-called support membrane type solid oxide fuel cell can have a structure strong against thermal stress and can be manufactured with high yield.

1. Solid oxide fuel cell The solid oxide fuel cell according to this embodiment includes one or more power generation layers described below. This solid oxide fuel cell is formed by joining a later-described laminated member and a laminated member with a bonding agent to form a gas seal portion between the two members.

  The “power generation layer” includes a solid electrolyte body, a fuel electrode provided on one surface of the solid electrolyte body, and an air electrode provided on the other surface. This solid electrolyte body has ion conductivity capable of moving at least a part of one of the fuel gas introduced into the fuel electrode or the combustion-supporting gas introduced into the air electrode during the operation of the battery as ions. Although what kind of ion can be conducted is not particularly limited, examples of the ion include oxygen ion and hydrogen ion. The fuel electrode is in contact with a fuel gas serving as a hydrogen source and functions as a negative electrode in a flat plate SOFC. Further, the air electrode is in contact with a combustion-supporting gas serving as an oxygen source and functions as a positive electrode in a flat plate type SOFC.

The “laminate member” is not particularly limited in material, application, shape, etc., as long as a later-described reservoir is provided at least at a part of the joining edge. Examples of the material of the laminated member include refractory metals and ceramics. This laminated member is preferably made of a heat-resistant metal from the viewpoint of the workability of the pool portion described later. Specific examples of the refractory metal include, for example, an Fe-based alloy, stainless steel, a nickel-based alloy, a chromium-based alloy, and the like. Examples of the Fe-based alloy include a practical Fe—Cr alloy ZMG232 manufactured by Hitachi Metals, Ltd. Examples of the stainless steel include ferritic stainless steel, martensitic stainless steel, and austenitic stainless steel. Examples of the nickel-based alloy include Inconel 600 (registered trademark), Inconel 718 (registered trademark), Incoloy 802 (registered trademark), and the like. Further, examples of the chromium-based alloy include Ducrloy CRF (94Cr5Fe1Y ₂ O ₃ ).

  Specific examples of the ceramic include oxide ceramics, nitride ceramics, carbide ceramics, silicide ceramics, and the like. Examples of the oxide ceramic include zirconia, magnesia, spinel, alumina, and titania. Moreover, the ceramic which consists of complex oxide containing 2 or more types of elements is mentioned. Examples of the nitride ceramic include silicon nitride, titanium nitride, and boron nitride. Examples of the carbide ceramic include silicon carbide and tungsten carbide. Examples of the silicide ceramic include molybdenum silicide. These ceramics can be selected depending on the use of the laminated member.

  For example, (1) a separator for isolating the power generation layer from other power generation layers stacked on the power generation layer, and (2) the above, depending on the structure of the flat plate SOFC. Examples include a separator for separating the flow path of the fuel gas and the flow path of the combustion-supporting gas in the power generation layer, (3) a frame body for housing the power generation layer, and (4) the solid electrolyte body. it can. The shape of this laminated member can be selected as appropriate according to its use.

  The “joining edge portion” usually means an outer peripheral side and / or an inner peripheral side edge portion of the joining surface portion of the laminated member. However, in the internal manifold type flat plate type SOFC, the joint edge portion can be an edge portion on the peripheral side of the manifold in the joint surface portion of the laminated member. Thus, even when a later-described pool portion is formed on the peripheral edge of the manifold, it is possible to sufficiently effectively improve the bonding strength of the gas seal portion and suppress the sagging of the bonding agent.

  The “reservoir portion” is not particularly limited in its shape, arrangement position, processing method, and the like as long as it can retain the bonding agent described later. From the viewpoints of the bonding strength of the gas seal portion and the capacity of the bonding agent, it is preferable that the pool member has a space shape that can effectively accommodate the excess bonding agent while suppressing the reduction of the bonding area as much as possible. Examples of the space shape include a chamfered portion, an R portion (fillet portion), a cutout portion that opens in at least two directions, and a groove portion that opens only in one direction. Moreover, this pool part can be provided continuously along the joining edge part, for example, or can be provided intermittently along the joining edge part.

  As long as the “layered member” is stacked on the layered member, the material, application, shape and the like are not particularly limited. Examples of the material of the laminated member include refractory metals and ceramics. As this heat-resistant metal and ceramic, for example, those exemplified for the laminated member can be applied. Moreover, as a use and shape of this to-be-laminated member, what was illustrated by the said laminated member etc. can be applied, for example. In addition, for example, in the same manner as the above-described laminated member, the laminated member may be provided with the above-described reservoir portion at least at a part of the joining edge portion. It is preferable that the member is not provided with the aforementioned reservoir.

Here, as the laminated member and the laminated member, for example, (1) the laminated member is a refractory metal and the laminated member is ceramic, and (2) the laminated member and the laminated member are refractory metal. (3) The laminated member is a ceramic and the laminated member is a refractory metal.
From the viewpoint of the workability of the pool portion with respect to the laminated member, the above-mentioned forms (1) and (2) are preferable. In particular, in the above (1) form, the metal-ceramic bonding surface may have poor wettability of the metallic bonding agent, and the excess bonding agent gathers locally into a spherical shape with a small contact angle. Since the short circuit failure may occur beyond the laminated member (ceramic) formed relatively thin, the formation of the pool portion is effective.

  In the case of the above (1) form, it is preferable that the member to be laminated has a protruding portion that protrudes laterally from the joint surface of the laminated member. As long as this "extrusion part" can exhibit the function of suppressing the sagging of the bonding agent, the shape, the amount of protrusion, the arrangement position, etc. are not particularly limited. The protruding portion can be removed by grinding or the like after joining, for example. Thereby, chipping of the ceramic member can be prevented. Further, in an internal manifold type flat plate type SOFC or the like, the protruding portion may become a gas flow resistance, but this can be solved, and it may be advantageous in terms of yield to be provided with a removal step. .

As a specific example of the form (1), for example, as shown in Example 1 described later, in the self-supporting membrane type flat plate SOFC, the laminated member is laminated with the power generation layer and other power generation layers. Examples include separators 31, 32, and 33 made of a heat-resistant metal for isolating the power generation layer, and the laminated member is a solid electrolyte body 21 that constitutes the power generation layer (see FIG. 1). .
Further, as a specific example of the form (1), for example, as shown in Example 2 to be described later, in the support membrane type flat SOFC, the laminated member is made of a refractory metal for housing the power generation layer. It can be mentioned that the first metal frame body 71 is a ceramic frame body 8 made of ceramic for housing the power generation layer (see FIG. 6).
Further, as a specific example of the form (2), for example, as shown in Example 2 to be described later, in a support membrane type flat SOFC, (a) the laminated member accommodates the power generation layer 1st and 2nd metal frame 71,72 which consists of a heat-resistant metal, and the said to-be-laminated member is a separator which consists of a heat-resistant metal for isolating the said electric power generation layer and the other electric power generation layer laminated | stacked on this electric power generation layer (B) The laminated member is a second metal frame 72 made of a heat-resistant metal for accommodating the power generation layer, and the laminated member is a fuel gas in the power generation layer. The form which is the separator 9 for isolating the flow path and the flow path of the combustion-supporting gas can be exemplified (see FIG. 6).

  The “bonding agent” is not particularly limited in its material, bonding method and the like as long as it contains a metal as a main component. Examples of the metal include one or a combination of two or more of Ag, Au, Pd, Pt, and the like. The above “main component” means that the total amount of metals as main components is 50% by mass or more when the bonding agent is 100% by mass, and the main component is 70 to 98% by mass. %, Particularly 90 to 98% by mass, and more preferably 93 to 97% by mass.

  This bonding agent can contain, for example, Ag and Pd. Thereby, the joint strength of the gas seal part mentioned later can be raised. In this case, the content of each of Ag and Pd is not particularly limited. However, when the total of Ag and Pd is 100% by mass, the content of Ag is 90 to 98% by mass, particularly 93 to 97% by mass. , Pd content is preferably 2 to 10% by mass, particularly 3 to 7% by mass. When the Ag content exceeds 98% by mass, that is, when the Pd content is less than 2% by mass, the oxidation resistance of the bonding agent is lowered, and a bonded portion having sufficient durability is formed. May not be possible. On the other hand, if the Ag content is less than 90% by mass, that is, if the Pd content exceeds 10% by mass, the bonding agent does not flow sufficiently during bonding, and the sealing performance of the bonded portion tends to decrease. is there.

For example, this bonding agent may further contain Cu and / or Ti in addition to the above Ag and Pd. When Cu is contained, even if it contains a larger amount of Pd than a bonding agent that does not contain Cu, it has sufficient fluidity and maintains excellent sealing performance. The contents of Ag, Pd and Cu when Cu is contained are not particularly limited, but the Ag content is 45 to 65 masses when the total of Ag, Pd and Cu is 100 mass%. %, Particularly 50 to 60% by mass, Pd content is preferably 15 to 35% by mass, especially 20 to 30% by mass, and Cu content is preferably 10 to 30% by mass, particularly preferably 15 to 25% by mass.
Further, by containing an appropriate amount of Ti, particularly high bonding strength can be obtained even when the bonding temperature is relatively low. The content of Ti is when the total of Ag, Pd and Ti is 100% by mass, or when Cu is contained, the total of Ag, Pd, Cu and Ti is 100% by mass. , 0.05 to 10% by mass, preferably 0.05 to 8% by mass, and more preferably 0.05 to 6% by mass.

The bonding temperature of the bonding agent is not particularly limited, but from the viewpoint of the flowability and bonding strength of the bonding agent, the flowability is set to be equal to or higher than the solidus temperature of the bonding agent and not higher than the temperature exceeding the liquidus temperature of 50 ° C. It is preferable. In addition, the bonding atmosphere of the bonding agent is not particularly limited as long as it is an inert atmosphere, and can be a vacuum and an inert gas atmosphere such as argon or nitrogen. The bonding atmosphere is particularly preferably a vacuum, and the bonding strength can be greatly improved in a vacuum atmosphere. The degree of vacuum is preferably 10 Pa or less, particularly 1 × 10 ^{−2 to} 1 Pa.

Hereinafter, the present invention will be described in detail by way of Example 1 with reference to the drawings.
(1) Structure of fuel cell In the self-supporting membrane type flat plate SOFC stack 1 according to the first embodiment, two single cells are illustrated as inter-cell separators 31 made of a heat-resistant metal (illustrated as “laminated members” according to the present invention). To have a laminated structure. The power generation layer 2 provided in each single cell is made of zirconia (ScSZ) stabilized by Sc, and has a thickness of 200 μm and is exemplified by a solid electrolyte body 21 (exemplified as a “layered member” according to the present invention). A fuel electrode 22 having a thickness of 30 μm made of Ni and ScSZ provided on the lower surface thereof, and an air electrode 23 having a thickness of 30 μm made of La _1-x Sr _x MnO ₃ composite oxide provided on the upper surface, Have The solid electrolyte body 21, the fuel electrode 22, and the air electrode 23 are all square in shape, and the solid electrolyte body 21 has a larger area than the fuel electrode 22 and the air electrode 23, and the fuel electrode 22 and the air electrode 23 are the same. It is a magnitude | size and is provided in the position which opposes.

  An upper separator 32 (illustrated as a “laminated member” according to the present invention) made of a heat-resistant metal is disposed on the upper power generation layer 2. Further, a lower separator 33 (illustrated as a “laminated member” according to the present invention) made of a heat-resistant metal is disposed below the lower power generation layer 2. A fuel gas channel 41 is formed on the upper surface of the inter-cell separator 31, and a combustion-supporting gas channel 42 is formed on the lower surface. In addition, a flow path 42 for a combustion-supporting gas is formed on the lower surface of the upper separator 32. Also. A fuel gas channel 41 is formed on the upper surface of the lower separator 33.

  The inter-cell separator 31, the upper separator 32, and the lower separator 33 are made of a practical Fe—Cr alloy ZMG232 manufactured by Hitachi Metals, Ltd. When another power generation layer is further laminated on the upper surface of the upper power generation layer 2, the upper separator 32 functions as an inter-cell separator. Further, when another power generation layer is further laminated on the lower surface of the lower power generation layer 2, the lower separator 33 functions as an inter-cell separator.

In the upper power generation layer 2, the lower peripheral edge of the upper separator 32 and the upper peripheral edge of the solid electrolyte body 21, the lower peripheral edge of the solid electrolyte body 21 and the upper peripheral edge of the inter-cell separator 31 are mainly composed of Ag containing Ti and Pd. The gas seal part 10 is formed by bonding with a bonding agent as a component.
In the lower power generation layer 2, the lower surface periphery of the inter-cell separator 31 and the upper surface periphery of the solid electrolyte body 21, the lower surface periphery of the solid electrolyte body 21 and the upper surface periphery of the lower separator 33 are mainly composed of Ag containing Ti and Pd. The gas seal part 10 is formed by bonding with a bonding agent as a component.

  In addition, as shown in FIG. 2, chamfers functioning as reservoirs for the bonding agent are formed on the outer peripheral side and inner peripheral side peripheral edge portions (bonding edge portions) at the bonding surface portions of the inter-cell separator 31 and the lower separator 33. Portions 311 and 331 are formed. These chamfered portions 311 and 331 have a 45 ° chamfered surface. Although not shown, chamfered portions 321 similar to the chamfered portions 311 and 331 are also formed on the outer peripheral side and inner peripheral side peripheral portions of the joint surface portion of the upper separator 32.

(2) Action / Effect of Fuel Cell In this solid oxide fuel cell 1, since the ionic conductivity is about twice as high as that of YSZ as the solid electrolyte body 21 and the fuel electrode 22, 750 is used. A stable current can be taken out even at an operating temperature of about ℃. Therefore, it is possible to use the separators 31, 32 and 33 made of a heat-resistant metal (ZMG232) instead of ceramic. Moreover, since the specific bonding agent containing Ag, Pd, and a small amount of Ti is used, the solid electrolyte body 21 and each separator 31, 32, 33 can be firmly bonded. Further, since the chamfered portions 311, 321, and 331 are provided along the bonding edge portions of the separators 31, 32, and 33, excess bonding agent at the time of bonding is stored in the collecting portions 311, 321, and 331, and the bonding agent It is possible to effectively prevent the occurrence of short circuit by suppressing the occurrence of sagging. As a result, a fuel cell having a structure strong against thermal stress can be manufactured with high yield. On the other hand, as shown in FIG. 3, in Comparative Example 1 in which the chamfered portion is not provided at the joining edge portion of each separator 31 </ b> A, 33 </ b> A, a short circuit failure S may occur due to sagging of the bonding agent.

  In the fuel cell 1 of the first embodiment, the outer peripheral end position of the solid electrolyte body 21 and the outer peripheral end positions of the separators 31, 32, and 33 are substantially the same. As shown in FIG. 4, the solid electrolyte body 21 may be provided with a protruding portion 211 that protrudes laterally from the joint surfaces of the separators 31, 32, and 33. Thereby, sagging of the bonding agent, that is, short circuit failure can be prevented more reliably. In addition, since this protrusion part 211 may cause the chip of a ceramic member, it is preferable to grind and remove after joining.

Hereinafter, the present invention will be described in detail with reference to the drawings by Example 2.
(1) Structure of Fuel Cell In the support membrane type flat SOFC stack 1 ′ according to the second embodiment, as shown in FIGS. 5 and 6, three single cells are two cells made of a refractory metal. It is laminated via the inter-layer separator 31 (illustrated as “a member to be laminated” according to the present invention). The power generation layer 2 provided in each single cell is made of a cermet of Ni and YSZ, and a fuel electrode 22 having a thickness of 1000 μm is used as a substrate. A solid electrolyte body 21 made of YSZ cermet and having a thickness of 30 μm is formed on the surface of the fuel electrode 22. The fuel electrode 22 and the solid electrolyte body 21 have a square planar shape and the same area. Furthermore, an air electrode 23 made of La _1-x Sr _x MnO ₃ -based composite oxide and having a thickness of 30 μm is formed on the surface of the solid electrolyte body 21. The air electrode 23 has a square planar shape and a smaller area than the solid electrolyte body 21.

The upper unit cell includes a nickel felt layer 5 disposed on the upper surface of the inter-cell separator 31, a fuel electrode 22 serving as a substrate, a solid electrolyte body 21, an air electrode 23, and an Inconel fiber mesh layer 6 in this order. . On the upper side of the Inconel fiber mesh layer 6, an upper separator 32 (illustrated as a “layered member” according to the present invention) made of a heat-resistant metal is disposed. The upper unit cell includes a first metal frame 71 and a second metal frame 72 (illustrated as “laminated members” according to the present invention) made of a heat-resistant metal for housing the power generation layer 2. Yes. The upper unit cell is exemplified as a ceramic frame body 8 (a “layered member” according to the present invention) made of an MgO—MgAl ₂ O ₄ sintered body that is an insulating ceramic for housing the power generation layer 2. ). Further, the upper unit cell includes an isolation separator 8 made of a heat-resistant metal for isolating the fuel gas channel 41 and the combustion-supporting gas channel 42 in the power generation layer 2.

The middle unit cell is composed of a nickel felt layer 5 disposed on the upper surface of the lower inter-cell separator 31, a fuel electrode 22 serving as a substrate, a solid electrolyte body 21, an air electrode 23, and an Inconel fiber mesh layer 6. Are provided in this order. The middle unit cell includes a first metal frame 71, a second metal frame 72, a ceramic frame 8, and an isolation separator 9 in the same manner as the upper unit cell.
Further, the lower unit cell includes a nickel felt layer 5 disposed on the upper surface of the lower separator 33, a fuel electrode 22 serving as a substrate, a solid electrolyte body 21, an air electrode 23, and an Inconel fiber mesh layer 6 in this order. The lower unit cell includes a first metal frame 71, a second metal frame 72, a ceramic frame 8, and an isolation separator 9 in the same manner as the upper unit cell and the intermediate unit cell.
The separators 31, 32, 33, the first and second metal frames 71, 72, and the separator 9 are made of a practical Fe—Cr alloy ZMG232 manufactured by Hitachi Metals, Ltd. When another unit cell is further stacked on the upper surface of the upper unit cell, the upper separator 32 functions as an inter-cell separator. Furthermore, when another unit cell is further laminated on the lower surface of the lower unit cell, the lower separator 33 functions as an inter-cell separator.

In the upper unit cell, the lower peripheral edge of the upper separator 32 and the upper surface of the first metal frame 71, the lower surface of the first metal frame 71 and the upper surface of the ceramic frame 8, the lower surface of the ceramic frame 8, and the upper surface of the isolation separator 9 The lower surface of the separator 9 and the upper peripheral edge of the solid electrolyte body 21, the lower surface of the separator 9 and the upper surface of the second metal frame 72, the lower surface of the second metal frame 72 and the upper peripheral edge of the inter-cell separator 31 are Ti. And Pd-containing Ag as a main component, and a gas seal portion 10 is formed between the respective members.
Further, in the single cell in the intermediate portion, the lower surface periphery of the inter-cell separator 31 and the upper surface of the first metal frame 71, the lower surface of the first metal frame 71 and the upper surface of the ceramic frame 8, and the lower surface of the ceramic frame 8 The upper surface of the separator 9, the lower surface of the separator 9 and the peripheral edge of the solid electrolyte body 21, the lower surface of the separator 9 and the upper surface of the second metal frame 72, the lower surface of the second metal frame 72, and the upper surface of the inter-cell separator 31. The peripheral edges are bonded with a bonding agent mainly composed of Ag containing Ti and Pd, and a gas seal portion 10 is formed between the respective members.
Furthermore, in the lower single cell, the lower surface periphery of the inter-cell separator 31 and the upper surface of the first metal frame 71, the lower surface of the first metal frame 71 and the upper surface of the ceramic frame 8, the lower surface of the ceramic frame 8 and the isolation separator 9, the lower surface of the separator 9 and the upper peripheral edge of the solid electrolyte body 21, the lower surface of the separator 9 and the upper surface of the second metal frame 72, the lower surface of the second metal frame 72 and the upper peripheral edge of the lower separator 33, Each is bonded with a bonding agent mainly composed of Ag containing Ti and Pd, and a gas seal portion 10 is formed between the respective members.

First metal frame 71, second metal frame 72, ceramic frame 8, isolation separator 9 in upper unit cell and middle unit cell, first metal frame 71 in upper unit cell, upper separator 32, and between cells The separator 31 has a combustion-supporting gas introduction pipe 421 and a combustion-supporting gas discharge pipe 422 formed therethrough. The combustion-supporting gas introduction pipe 421 and the combustion-supporting gas discharge pipe 422 open to the gas flow path 42 corresponding to the air electrode 23 of each single cell.
In addition, the first metal frame 71, the second metal frame 72, the ceramic frame 8, the isolation separator 9 in the lower unit cell and the intermediate unit cell, the second metal frame 72 in the upper unit cell, the lower separator 33, and A fuel gas introduction pipe and a fuel gas discharge pipe (not shown) are formed through the inter-cell separator 31 so as to penetrate therethrough. These fuel gas introduction pipes and fuel gas discharge pipes open to gas flow paths 41 corresponding to the fuel electrodes 22 of each single cell.

In each single cell, as shown in FIG. 7, the outer peripheral side and the inner peripheral side of the joint surface of the first metal frame 71 and the peripheral part of the manifold (the above-described various gas introduction pipes and exhaust pipes). A chamfered portion 711 that functions as a reservoir for the bonding agent is formed. The chamfered portion 711 has a 45 ° chamfered surface.
Further, in each single cell, the chamfered portion 711 is formed on the outer peripheral side and the inner peripheral side peripheral portion and the peripheral portion of the manifold (the various gas introduction pipes and the exhaust pipe) in the joint surface portion of the second metal frame 72. A chamfered portion 721 is formed.

(2) Extraction of Electric Power from Fuel Cell In this flat plate type SOFC stack 1 ′, the fuel electrode 22 of the upper single cell is electrically connected to the inter-cell separator 31 through the nickel felt layer 5. The inter-cell separator 31 is electrically connected to the air electrode 23 of the intermediate single cell via the Inconel fiber mesh layer 6. The intermediate unit single-cell fuel electrode 22 is electrically connected to the inter-cell separator 31 via the nickel felt layer 5. The inter-cell separator 31 is electrically connected to the air electrode 23 of the lower single cell via the Inconel fiber mesh layer 6. In this way, the upper unit cell, the middle unit cell, and the lower unit cell are each connected in series. Further, the stack is heated to a predetermined operating temperature, a fuel gas such as hydrogen is introduced into the fuel gas introduction pipe and brought into contact with the fuel electrode 22, and a combustion supporting gas such as air is supplied to the combustion supporting gas introduction pipe 421. When it is introduced and brought into contact with the air electrode 23, an electromotive force is generated between the fuel electrode 22 and the air electrode 23, and this power can be taken out to function as a power generator. Electric power is taken out to the lower separator 33 via the nickel felt layer 5 disposed on the lower surface of the lower unit cell on the fuel electrode side, and the Inconel fiber mesh disposed on the upper surface of the upper unit cell on the air electrode side. It is taken out by the upper separator 32 through the layer 6, and the electric power of the entire stack can be taken out between the upper separator 32 and the lower separator 33.

(3) Operation and effect of fuel cell In this solid oxide fuel cell 1 ′, the three power generation layers are each of the fuel electrode support type, and in this structure, current can be taken out even at an operating temperature of about 700 ° C. it can. Therefore, each separator 31, 32, 33, the 1st and 2nd metal frame 71, 72 can be formed with a heat-resistant metal (ZMG232) instead of a ceramic. Moreover, since the specific joining agent containing Ag, Pd, and a small amount of Ti was used, members can be joined firmly. Further, since the chamfered portions 711 and 721 are provided along the joining edge portions of the first and second metal frame bodies 71 and 72, excess joining agent at the time of joining is accumulated in the collecting portions 711 and 721, and the joining agent The occurrence of this sagging can be suppressed, and the occurrence of short circuit failure and the blockage inside the manifold can be effectively prevented. As a result, a fuel cell having a structure strong against thermal stress can be manufactured with high yield. On the other hand, as shown in FIG. 8, in the comparative example 2 in which the chamfered portion is not provided at the joint edge portion of the first and second metal frame bodies 71A and 72A, the short circuit defect S occurs due to the sagging of the bonding agent. There is a case.

  In the fuel cell 1 ′ of the second embodiment, the outer peripheral and inner peripheral end positions of the ceramic frame 8 and the outer peripheral and inner peripheral end positions of the first and second metal frame 71 and 72 are substantially the same. However, the present invention is not limited to this. For example, as shown in FIG. 9, the ceramic frame 8 is provided with a protruding portion 81 that protrudes outward from the joint surface of the first and second metal frames 71 and 72. May be. Thereby, sagging of the bonding agent, that is, short circuit failure can be prevented more reliably. In addition, since this protrusion part 81 may become the cause of the ceramic member's chipping and the resistance of the gas passage in a manifold, it is preferable to grind and remove after joining.

In addition, in this invention, it can be set as the Example variously changed within the range of this invention according to the objective and use, without being restricted to the said Example 1 and Example 2. FIG. That is, in Examples 1 and 2 described above, the chamfered portions 311, 321, 331, 711, and 721 are exemplified as the bonding agent reservoir, but the present invention is not limited to this. For example, as shown in FIG. The reservoir portion may be constituted by a notch portion a or a slit-shaped groove portion b formed by opening the outer side and the upper side (or the lower side). Furthermore, it is good also as R part (fillet part) which has a curved surface, many holes, etc.
Moreover, in the said Example 1 and 2, although the pool part formed continuously along the joining edge part of each member was illustrated, it is not limited to this, For example, intermittently along the joining edge part of each member It is good also as the reservoir part formed automatically.

Moreover, in the said Example 1, although the pool part was formed in the joint edge part of the outer peripheral side of each separator 31, 32, 33, and an inner peripheral side, it is not limited to this, For example, each separator 31, 32 , 33 may be formed only at the joining edge on the outer peripheral side.
In the first embodiment, the reservoirs are formed in the separators 31, 32, 33. However, the present invention is not limited to this, and the reservoirs are formed in the solid electrolyte body 21 together with the separators 31, 32, 33. Alternatively, the reservoir portion may be formed only in the solid electrolyte body 21 without forming the reservoir portion in each of the separators 31, 32, 33. Further, a pool portion may be formed in at least one of the separators 31, 32, and 33.

In the second embodiment, the reservoirs are formed on the outer peripheral side, the inner peripheral side, and the manifold peripheral side of each metal frame 71, 72. However, the present invention is not limited thereto. The reservoir portions may be formed only on the outer peripheral side and the inner peripheral side of 71 and 72, or the reservoir portions may be formed only on the outer peripheral side of each metal frame 71 and 72.
In the second embodiment, the reservoirs are formed in the metal frames 71 and 72. However, the present invention is not limited to this, and the reservoirs are formed in the ceramic frame 8 together with the metal frames 71 and 72. Alternatively, the reservoirs may be formed only in the ceramic frame 8 without forming the reservoirs in the metal frames 71 and 72. In addition, the reservoir portion may be formed only in one of the metal frames 71 and 72.

  It is suitably used as a fuel cell application for vehicles, cogeneration, distributed power sources, thermal power generation alternatives, and the like.

1 is a schematic view showing a longitudinal section of a fuel cell according to Example 1. FIG. It is an expansion schematic diagram of the A arrow view part of FIG. It is explanatory drawing for demonstrating the comparative example 1 (there is no accumulation part). It is explanatory drawing for demonstrating the other form of junction part structure. 6 is an external perspective view of a fuel cell according to Example 2. FIG. It is a schematic diagram which shows the BB line cross section of FIG. It is an expansion schematic diagram of the B arrow part of FIG. It is explanatory drawing for demonstrating the comparative example 2 (there is no reservoir part). It is explanatory drawing for demonstrating the other form of junction part structure. It is explanatory drawing for demonstrating the other form of a reservoir part.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,1 '; Solid electrolyte type fuel cell, 2; Power generation layer, 21; Solid electrolyte body, 211; Overhang part, 22; Fuel electrode, 23; Air electrode, 31; Inter-cell separator, 32; Lower separator, 311, 321, 331; chamfered portion, 71; first metal frame, 72; second metal frame, 711, 721; chamfered portion, 8; ceramic frame, 81; Department.

Claims (6)

A power generation layer (2) having a solid electrolyte body (21), a fuel electrode (22) provided on one surface of the solid electrolyte body, and an air electrode (23) provided on the other surface, and a laminated member (31, 32, 33, 71) and the laminated member (21, 8) are joined with a joining agent mainly composed of metal to form a gas seal portion (10) between the members. In the fuel cell (1, 1 ′),
At least the laminated member of the laminated member and the laminated member is provided with a reservoir portion (311, 321, 331, 711, 721) in which at least a part of the joining edge portion can accumulate the bonding agent. A solid oxide fuel cell.   The solid oxide fuel cell according to claim 1, wherein the laminated member is made of a heat-resistant metal.   3. The solid oxide fuel cell according to claim 2, wherein the pool portion is formed of a chamfered portion (311, 321, 331, 711, 721).   4. The solid oxide fuel cell according to claim 2, wherein the laminated member is made of ceramic, and the protruding member is provided with a protruding portion (211, 81) that protrudes from a joint surface of the laminated member.   The laminated member is a separator (31, 32, 33) made of a refractory metal for separating the power generation layer and another power generation layer, and the laminated member is the solid electrolyte body (21). The solid oxide fuel cell according to any one of 1 to 4.   The laminated member is a metal frame (71) made of a refractory metal for housing the power generation layer, and the laminated member is a ceramic frame (8) made of ceramic for housing the power generation layer. The solid oxide fuel cell according to any one of claims 1 to 4.

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