JP6389133B2 - Fuel cell stack - Google Patents

Description

  The present invention relates to a fuel cell stack including one or a plurality of single unit fuel cells each having an air electrode and a fuel electrode in a solid electrolyte, for example.

Conventionally, as a fuel cell, for example, a solid oxide fuel cell (SOFC) using a solid electrolyte (solid oxide) is known.
In this solid oxide fuel cell, as a power generation unit, for example, a flat fuel electrode that contacts a fuel gas is provided on one side of a flat solid electrolyte, and an oxidant gas (for example, air) is contacted on the other side. A flat plate type fuel cell single cell provided with a flat plate oxidant electrode (air electrode) is used.

  In addition, in order to obtain a desired voltage, a current collector is disposed between the fuel electrode or air electrode as an electrode and the interconnector, and a plurality of fuel cell single cells are connected via the interconnector and the current collector. Stacked fuel cell stacks have been developed.

  In this type of fuel cell stack, the expansion and contraction due to the influence of the thermal cycle that reaches from the normal temperature (for example, room temperature) to the high temperature during power generation (for example, 700 ° C. to 1000 ° C.) and drops again to the room temperature, that is, the temperature change of the member As a countermeasure against the current collector, various techniques for improving the electrical connection between the fuel electrode and the current collector have been proposed (see Patent Documents 1 and 2).

  Further, in recent years, as illustrated in FIG. 13A, between the fuel electrode P1 and the fuel electrode side current collector (the fuel electrode side current collector P3 whose elastic modulus is smaller than that of the air electrode side current collector P5). In addition, in order to ensure sufficient electrical connection between the air electrode P4 and the air electrode side current collector (hard metal air electrode side current collector P5), fuel is produced by the bonding materials P6, P7, etc. Techniques have been developed for joining the electrode P1 and the fuel electrode side current collector P3 and the air electrode P4 and the air electrode side current collector P5.

JP 2012-186026 A JP2013-55042A

  However, even in the above-described conventional technology, the electrical connection between the electrode and the current collector may be reduced due to the damage of the bonding material provided between the electrode and the current collector due to the thermal cycle. There is a need for improvement.

  Specifically, as shown in FIG. 13 (a), the fuel cell has an air electrode side current collector P5 protruding from one surface of the flat interconnector P8 during assembly or operation at a high temperature. As shown in FIG. 13B, when the temperature is lowered from a high temperature during operation to normal temperature (for example, room temperature), the member is contracted during cooling. The outer peripheral side of the interconnector P8 may be bent by the thermal stress. As a result, the air electrode side current collector P5 in the vicinity of the outer periphery may be peeled off from the air electrode P4 side together with a part of the damaged bonding material P7. Further, the tip of the air electrode side current collector P5 may be peeled off from the solid electrolyte P9 side together with a part of the air electrode P4.

  This is because the fuel electrode P1 and the fuel electrode side current collector P3 are joined by the joining material P6, and therefore, when the interconnector P8 is curved, the fuel electrode side current collector P3 and the interconnector P8 are connected to each other. It is considered that force tension is generated between them, and part of the bonding material P7 and part of the air electrode P4 may be peeled off.

  Thereafter, when the operating temperature is raised again, as shown in FIG. 13 (c), the interconnector P8 returns to a flat plate shape, but the parts of the bonding material P4 damaged at the tip of the air electrode side current collector P5 Or a part of the air electrode P4 adhering to the tip of the air electrode side current collector P5 is merely in contact with the solid electrolyte P9 (see the arrow portion). A sufficient electrical connection cannot be obtained. As a result, there is a problem that the power generation performance of the fuel cell is lowered.

  The present invention has been made in view of such a problem, and even when a thermal cycle is applied, high electrical connection between the current collector and the electrode can be ensured, and a decrease in power generation performance can be suppressed. An object is to provide a fuel cell stack.

[1] First, the fuel cell stack of the present invention will be described.
(1) The fuel cell stack according to the first aspect of the present invention is a flat plate type fuel cell single cell having a first electrode on one side of a flat solid electrolyte and a second electrode on the other side. A first current collector electrically connected to the first electrode; a second current collector electrically connected to the second electrode; the first electrode and the first current collector; In a fuel cell stack comprising a first joint that joins the second electrode, and a second joint that joins the second electrode and the second current collector, the region where the first joint is disposed (R1) ) Is formed inside the outer periphery (G2) of the region (R2) in which the first current collector is disposed, and the outer periphery (R3) of the region (R3) in which the second joint portion is disposed. (G3) It is formed inside.

In the first aspect, the outer periphery of the region where the first joint portion is disposed is formed inside the outer periphery of the first current collector, and is formed inside the outer periphery of the region where the second joint portion is disposed. ing.
Accordingly, when the temperature of the fuel cell stack decreases from a high temperature during operation to a low temperature such as room temperature, for example, when the second electrode is an air electrode, an interconnector that is electrically connected to the air electrode When the second current collector is bent and subjected to thermal stress that peels off from the second electrode, the outer peripheral portion of the first current collector (without the first joint) is easily separated from the first electrode, The pulling of the force described above is unlikely to occur, and therefore, the second joint portion and part of the air electrode are not easily separated.

  Therefore, even when the temperature rises again and the curvature of the interconnector, for example, returns, the second current collector, the second electrode, and the second electrode and the solid electrolyte remain joined. High electrical connection (conductivity) between the current collector and the second electrode and between the second electrode and the solid electrolyte can be maintained. In other words, it is possible to prevent the electrical connection from changing before the thermal stress is generated and after the thermal stress is generated.

  As described above, in the first aspect, even when the fuel cell stack is subjected to a thermal cycle in which the fuel cell stack rises from room temperature (for example, 25 ° C.) to a high temperature during operation and then drops to room temperature again, Since it can suppress that an electric body peels from the 2nd electrode side and a 2nd electrical power collector peels from a solid electrolyte side with a part of 2nd electrode, always maintains a high electrical connection (conductivity). be able to. Therefore, there is a remarkable effect that power generation performance can be secured stably.

The region (R3) in which the second bonding portion is disposed and the region (R4) in which the second current collector is disposed may be the same or different (the same applies hereinafter).
(2) In the fuel cell stack of the present invention, the outer periphery (G1) of the region (R1) where the first joint portion is disposed is the outer periphery (G4) of the region (R4) where the second current collector is disposed. On the other hand, it is preferable to be formed inside 0.4 cm or more over the entire circumference.

  In the case of (2) above, even when a thermal cycle is applied, for example, when the interconnector is curved, the second current collector and the second electrode and the second electrode and the solid electrolyte are more difficult to peel off. There is an effect that power generation capacity can be stably maintained.

  (3) In the fuel cell stack of the present invention, the first electrode is a fuel electrode, the second electrode is an air electrode, the first current collector is a fuel electrode side current collector, and the second current collector is an air electrode. A side current collector is preferred.

  The gas supplied to the air electrode side is an oxidant gas (for example, air), and the joint portion that joins the air electrode and the air electrode side current collector prevents deterioration due to oxidation of the joint portion. Conductive oxides are used. Once the joint formed by the conductive oxide is broken, the conductivity is significantly lowered. Moreover, since the junction part formed with the electroconductive oxide couple | bonds with the air electrode which is an oxide chemically, when stress is added by a thermal cycle, the air electrode itself will be destroyed. When the air electrode, which is an electrode, is destroyed, power generation at the destroyed location becomes impossible.

  On the contrary, since the gas supplied to the fuel electrode side is a reducing gas (for example, hydrogen), the joint part that joins the fuel electrode and the fuel electrode side current collector is deteriorated due to oxidation of the joint part. The metal material is used. In addition, the fuel electrode itself also contains a metal material due to the reducing action of the reducing gas, and even in a region where no joint exists, the fuel electrode side assembly and the fuel electrode come into contact with each other to obtain an electrical connection. Is possible.

  Therefore, in the case of the above (3), even when a stress is applied by a thermal cycle, the air electrode is difficult to break, and the joint portion made of a conductive oxide is difficult to break. Electrical connection such as between the side current collectors can be ensured.

  (4) In the fuel cell stack of the present invention, the first current collector includes a spacer having elasticity and a conductive member having a conductor, and the spacer is sandwiched between the conductive members, The conductive member and the first electrode are bonded via the first bonding portion.

Therefore, the first current collector has a larger elastic amount than the second current collector (in other words, the first current collector is more easily elastically deformed than the second current collector).
According to the above (4), even when a thermal stress is applied to the fuel cell stack by a thermal cycle, the first current collector can follow the deformation of each member due to the thermal stress by the elastic deformation of the spacer. Therefore, high electrical connection (and hence conductivity) between the first current collector and the first electrode can be ensured.
[2] Next, each configuration of the fuel cell stack of the present invention will be described.

In the present invention, the fuel cell stack includes one or more flat plate fuel cell single cells.
-When a 1st junction part, a 1st electrical power collector, and a 2nd junction part are comprised from one thing (member etc.), with each area | region, a 1st junction part and a 1st electrical power collector are planar views The outer periphery of the body and the second joint is indicated by outlines of the first joint, the first current collector, and the second joint.

  On the other hand, when a 1st junction part, a 1st electrical power collector, and a 2nd junction part are comprised from multiple things (members etc.), each area | region connects the outer peripheral side of each member etc. by planar view. It is a range surrounded by a line. Specifically, it is within a range surrounding each member or the like so as to be bundled with, for example, a ring, and the outer periphery of the region is an outline indicated by the ring.

A fuel electrode can be used as the first electrode, a fuel electrode side current collector can be used as the first current collector, an air electrode can be used as the second electrode, and an air electrode side current collector can be used as the second current collector. Can be adopted.
Alternatively, an air electrode can be adopted as the first electrode, an air electrode side current collector can be adopted as the first current collector, a fuel electrode can be adopted as the second electrode, and a fuel electrode side current collector as the second current collector. Can be adopted.

-As a material which comprises a 1st junction part and a 2nd junction part, the material etc. which have various electroconductivity etc. are employable, for example.
For example, Ni and Pt can be adopted as the first joint (for example, the fuel electrode joint). Further, as the second joint (for example, the joint of the air electrode), an Ag—Pd alloy, a perovskite-based material (for example, LSCF + Cu), a spinel-based material (for example, MnCu ₂ O ₄ , CuMn ₂ O ₄ ), or the like. Can be adopted. Examples of the current collector include one integrated with an interconnector (for example, a protrusion protruding from the surface) and one joined to the interconnector by a brazing material or the like.

  -Fuel gas and oxidant gas are mentioned as a raw material in generating electric power with a fuel cell stack. In the fuel cell stack, the fuel gas refers to a gas (for example, hydrogen) supplied to the fuel electrode side, and the oxidant gas refers to a gas (for example, air, strictly oxygen in the air) supplied to the air electrode side. ).

  As the spacer, a material having a larger elastic amount than the second current collector, such as mica, can be used, and as the conductive member, a material such as stainless steel or Ni can be used. Accordingly, the first current collector can have an elastic structure (in other words, the first current collector is more easily elastically deformed than the second current collector).

1 is a perspective view of a fuel cell stack according to a first embodiment. It is a perspective view of the electric power generation unit which comprises a fuel cell stack. It is a perspective view which decomposes | disassembles and shows a power generation unit. An air electrode side collector is shown typically, (a) is the bottom view on the air electrode side, (b) is the side view. It is a perspective view which shows the fuel cell single cell joined to the separator. It is a perspective view which expands and shows a fuel electrode side collector and its principal part. It is a top view which expands and shows typically a fuel electrode side collector. It is sectional drawing which fractures | ruptures a power generation unit in the lamination direction (XX cross section of FIG. 2), and expands and shows the principal part typically. It is explanatory drawing which shows each area | region and the range of each outer periphery by planar view inside a power generation unit. (A)-(e) is explanatory drawing which shows typically the principal part in the electric power generation unit of 2nd-6th embodiment (in planar view). It is sectional drawing which fractures | ruptures the electric power generation unit of 8th Embodiment in the lamination direction (XX cross section of FIG. 2), and expands the principal part typically. 6 is a graph showing the experimental results of Experimental Example 1. It is explanatory drawing of a prior art.

Hereinafter, a solid oxide fuel cell stack will be described as an example of a fuel cell stack to which the present invention is applied.
[First Embodiment]
a) First, a schematic configuration of the fuel cell stack according to the first embodiment will be described.

  As shown in FIG. 1, the solid oxide fuel cell stack (hereinafter also referred to simply as “fuel cell stack”) 1 of the first embodiment includes a fuel gas (for example, hydrogen) and an oxidant gas (for example, It is a device that generates electricity by being supplied with air (specifically, oxygen in the air). In the drawings, the oxidant gas is indicated by “O”, and the fuel gas is indicated by “F”. “IN” indicates that gas is introduced, and “OUT” indicates that gas is discharged (the same applies hereinafter).

  The fuel cell stack 1 includes end plates 3 and 5 disposed at both ends in the vertical direction (stacking direction) in FIG. 1, and a plurality of power generation units 7 (see FIG. 2) between them (for example, 6 to 40). Fuel cell stack.

  The end plates 3 and 5 and each power generation unit 7 are provided with a plurality of (for example, eight) through-holes 9 through which the end plates 3 and 5 and the respective power generation units 7 penetrate in the stacking direction (vertical direction in FIG. 1). 11a, 11b, 11c, 11d, 11e, 11f, 11g, 11h (collectively referred to as 11) and each nut 13 screwed to each bolt 11, the end plates 3, 5 and each power generation unit 7 are fixed together. Has been.

  In addition, the specific (four) bolts 11b, 11d, 11f, and 11h among the bolts 11 have an internal flow path 14 through which an oxidant gas or a fuel gas flows along the axial direction (vertical direction in FIG. 1). Is formed. The bolt 11b is used for discharging fuel gas, the bolt 11d is used for discharging oxidant gas, the bolt 11f is used for introducing fuel gas, and the bolt 11h is used for introducing oxidant gas.

In the present embodiment, for convenience of description, directions such as “up” and “down” are described with reference to the directions of the drawings, but the directionality of the actual fuel cell stack is not specified.
b) Next, the configuration of the power generation unit 7 will be described in detail.

  As shown in FIG. 3, the power generation unit 7 includes interconnectors 17 a and 17 b (generally referred to as 17) on both sides of the fuel cell single cell 15 in the thickness direction (vertical direction in FIG. 3). Note that one of the end plates 3 and 5 is used outside the power generation unit 7 at both ends in the stacking direction of the fuel cell stack 1 instead of the interconnector 17.

  That is, the power generation unit 7 includes a metal interconnector 17a, an air electrode insulating frame 23, a metal separator 25, a metal fuel electrode frame 27, a fuel electrode insulating frame 29, and a metal interconnector. 17b and the like are laminated. In addition, each through-hole 9 in which each bolt 11 is inserted is formed in each of the stacked members 17, 23 to 29.

  Among these, the fuel cell single cell 15 mentioned later is joined to the separator 25. A convex air electrode side current collector 37 (see FIG. 4), which is a conductive member integral with the interconnector 17, is provided in a flow path (air flow path through which the oxidizing gas flows) in the air electrode insulating frame 23. The fuel electrode side current collector 41, which is a conductive member, is disposed in the flow path (fuel flow path through which the fuel gas flows) 39 in the frame of the fuel electrode frame 27 (or the fuel electrode insulation frame 29). Yes.

Hereinafter, each configuration will be described in more detail.
The interconnector 17 is made of a conductive plate material (for example, a metal plate such as stainless steel such as SUS430). The interconnector 17 ensures continuity between the continuous fuel cell units 15 in the fuel cell stack 1 and prevents gas mixing between the fuel cell units 15 (and thus between the power generation units 7). is there. In addition, the interconnector 17 should just be arrange | positioned when arrange | positioning between the adjacent fuel cell single cells 15. FIG. Therefore, the lower interconnector 17 of one power generation unit 7 in the fuel cell stack 1 is shared with the upper interconnector 17 of the adjacent power generation unit 7.

  As shown in FIG. 4, the interconnector 17 is opposed to, for example, a plate-like portion 18 having a length of 150 mm × width of 150 mm × thickness 2 mm, and one surface of the plate-like portion 18, specifically the air electrode 55 (see FIG. 5). And a large number of air electrode side current collectors 37 formed on the surface to be operated. In FIG. 4, the number of air electrode side current collectors 37 to be described is reduced and simplified.

  The air electrode side current collectors 37 are arranged in a grid so as to be 12 columns × 12 columns. Each air electrode side current collector 37 has a block shape (cuboid shape) of 4 mm in length, 4 mm in width, and 1 mm in thickness, and is formed so as to protrude from the plate-like portion 18 toward the air electrode 55.

  Here, the outer periphery of the region R4 where the air electrode side current collector 37 is disposed is a line connecting the side adjacent to the outer peripheral side of the outermost air electrode side current collector 37 with a shortest distance in plan view. A square-shaped outer periphery G4 (enclosed by a dotted line). Therefore, the region R4 is within the range of the outer periphery G4.

  In plan view, the region R4 in which the air electrode side current collector 37 is disposed and the air electrode bonding layer that is the second bonding portion (a layer that bonds the air electrode side current collector 37 and the air electrode 55 described later: This is the same as the region R3 in which FIG. Accordingly, the outer periphery G4 of the region R4 where the air electrode side current collector 37 is disposed and the outer periphery G3 of the region R3 where the air electrode bonding layer (second bonding portion) 71 is disposed are the same.

  Returning to FIG. 3, the air electrode insulating frame 23 is a square frame-like plate material having electrical insulation, and is a mica frame made of soft mica. The air electrode insulating frame 23 is formed with a rectangular opening 23 a constituting the air flow path 35 at the center thereof (in a plan view as viewed from the thickness direction).

  Further, in the air electrode insulating frame 23, the long side communication holes 43 d and 43 h are respectively connected to the frame portions on each side where the pair of through holes 9 (9 d and 9 h) are provided so as to communicate with the respective through holes 9. Is provided. Further, the air electrode insulating frame 23 is provided with a plurality of grooves 45d and 45h as portions (communication portions) through which air passes so that the communication holes 43d and 43h communicate with the opening 23a.

  The separator 25 is a rectangular frame-like conductive plate material (for example, a metal plate such as stainless steel such as SUS430). As shown in FIG. 5, the separator 25 is brazed with the outer peripheral edge (upper surface) of the unit cell 15 on the inner peripheral edge (lower surface) along the rectangular opening 25a at the center. It is joined. That is, the fuel cell single cell 15 is joined so as to close the opening 25 a of the separator 25.

  In the single fuel cell 15, a solid electrolyte body (solid electrolyte layer) 51, a fuel electrode 53, and an air electrode 55 (the outer shape of which is smaller than the solid electrolyte layer 51 and the fuel electrode 53 in plan view) are integrally laminated. The separator 25 is bonded to the upper surface of the outer peripheral edge portion of the solid electrolyte layer 51.

  Therefore, the air flow path 35 and the fuel flow path 39 are separated by the separator 25 to which the single fuel cell 15 described above is joined so that the oxidant gas and the fuel gas are not mixed inside the power generation unit 7. ing.

Returning to FIG. 3, the fuel electrode frame 27 is a rectangular frame-shaped plate material made of stainless steel such as SUS430 having conductivity.
Like the air electrode insulating frame 23, the fuel electrode insulating frame 29 is a square frame-like plate material having electrical insulation, and is a mica frame made of soft mica. Similar to the air electrode insulation frame 23, the fuel electrode insulation frame 29 has a long opening communicating with a rectangular opening 29 a constituting the fuel passage 39 in the center and the pair of through holes 9 (9 b, 9 f). The communication holes 57b and 57f, and the grooves 59b and 59f that connect the communication holes 57b and 57f and the opening 29a are provided.

  As shown in FIGS. 6 and 7, the fuel electrode side current collector 41 includes a spacer 61 that is a core material made of mica and a metal conductive plate that is a conductive member (for example, a flat plate-shaped net or foil made of nickel). 63 is a known lattice-like member (see, for example, the current collecting member 19 described in JP2013-55042A). In FIG. 7, the number of joining pieces 63a is reduced and shown in a simplified manner.

  Specifically, the fuel electrode side current collector 41 includes a spacer (ladder mica) 61 in which a number of long holes 61 a are opened in parallel, and a conductive member in which each joining piece 63 a of the conductive plate 63 is bent and attached to the spacer 61. It consists of a plate 63.

  The amount of elasticity of the air electrode side current collector 37 is smaller than the amount of elasticity of the fuel electrode side current collector 41 (specifically, the amount of elasticity of the spacer 61). The elastic amount of the side current collector 41 can be measured as follows.

  First, a sample for a compression test is prepared for each of the spacer 61 and the air electrode side current collector 37. The sample size was 6.5 mm × 4 mm, and the thickness was 0.4 mm. Here, the size of each sample may be any size as long as both are the same.

Next, the sample is compressed with 10 kg using a compression tester, and the amount of change (mm) in thickness at that time is measured to obtain the maximum displacement.
Furthermore, the compression of 10 kg is released, and the amount of restoring displacement from the maximum amount of displacement is measured.

From this test, the larger the amount of restoring displacement means that the amount of elasticity is larger, and conversely, the smaller the amount of restoring displacement means that the amount of elasticity is smaller.
Here, as will be described later, the outer periphery G1 of the region R1 in which the joining piece 63a is joined to the fuel electrode 53 (that is, the region R1 in which the first joining portion is disposed) is disposed, for example, on the outermost periphery in plan view. A frame-shaped outer periphery G1 (enclosed by a dotted line) formed from a line connecting the adjacent side and the side adjacent to the outer peripheral side of the connecting piece 63a in one row inside the connecting piece 63a. . Accordingly, the region R1 is within the range of the outer periphery G1.

  Moreover, the outer periphery G2 of the region R2 (that is, the region R2 where the first current collector is disposed) in which the joining piece 63a is in contact with the fuel electrode 53 in a plan view is, for example, a joint disposed on the outermost periphery. This is a square-shaped outer periphery G2 (enclosed by a dotted line) formed from a line connecting the side on the outer peripheral side of the piece 63a and an adjacent side with the shortest distance. Accordingly, the region R2 is within the range of the outer periphery G2.

c) Next, the fuel cell single cell 15 will be described in detail.
As shown in FIG. 8, the fuel cell single cell 15 has a so-called fuel electrode support membrane type structure, and is formed on a thin solid electrolyte layer 51 and one side thereof (downward in FIG. 8). Further, a fuel electrode (anode: AN) 53 and a thin film air electrode (cathode: CA) 55 formed on the other side (upper side in FIG. 8) are integrally laminated.

  An air flow path 35 is provided on the air electrode 55 side of the fuel cell single cell 15, and a fuel flow path 39 is provided on the fuel electrode 53 side. The air flow direction in the air flow path 35 is perpendicular to the paper surface, and the fuel gas flow direction in the fuel flow path 39 is the left-right direction (left to right) in FIG.

Among these, the air electrode 55 is a porous layer through which the oxidant gas can pass, and the open porosity thereof is, for example, 30% in the range of 20 to 50%.
Examples of the material constituting the air electrode 55 include metals, metal oxides, and metal composite oxides. Examples of the metal include metals such as Pt, Au, Ag, Pd, Ir, Ru, and alloys thereof. Examples of the metal oxide include oxides such as La, Sr, Ce, Co, Mn, and Fe, such as La ₂ O ₃ , SrO, Ce ₂ O ₃ , Co ₂ O ₃ , MnO ₂ , and FeO. As the composite oxide, composite oxides containing La, Pr, Sm, Sr, Ba, Co, Fe, Mn, etc. (La _1-x Sr _x CoO ₃ -based composite oxide, La _1-x Sr _x FeO ₃₎ system composite _{oxide, La 1-x Sr x Co} 1-y Fe y O 3 composite _{oxide, La 1-x Sr x MnO} 3 composite _{oxide, Pr 1-x Ba x CoO} 3 composite oxide, Sm _1-x Sr _x CoO ₃ composite oxide) or the like can be used.

  The solid electrolyte layer 51 is a dense layer made of a solid oxide, and can move the oxidant gas (oxygen) introduced into the air electrode 55 as ions during operation (power generation) of the fuel cell stack 1. It has ionic conductivity.

  Examples of the material constituting the solid electrolyte layer 51 include zirconia-based, ceria-based, and perovskite-based electrolyte materials. Examples of zirconia-based materials include yttria stabilized zirconia (YSZ), scandia stabilized zirconia (ScSZ), and calcia stabilized zirconia (CaSZ), and yttria stabilized zirconia (YSZ) is generally used. There are many examples. For ceria-based materials, so-called rare earth element-added ceria is used, and for perovskite-based materials, perovskite-type double oxides containing lanthanum elements are used.

  The fuel electrode 53 is a porous layer through which fuel gas can pass, and the open porosity thereof is, for example, 35% in the range of 20 to 60%. Although not shown, the fuel electrode 53 is composed of an active layer that causes a catalytic reaction by exchange of electrons and a support layer that supports the active layer.

Examples of the material constituting the fuel electrode 53 include ZrO ₂ ceramics such as zirconia and CeO ceramics stabilized by at least one of metals such as Ni and Fe and rare earth elements such as Sc and Y. And a mixture of these with ceramics. Further, a metal such as Ni, or a cermet or Ni-based alloy of Ni and the ceramic can be used.

d) Next, the region and outer periphery of each member, which is a main part of the first embodiment, will be described.
In the first embodiment, the air electrode bonding layer (second bonding) having conductivity is provided between the front end surface (bottom surface) of all the air electrode side current collectors 37 on the air electrode 55 side and the surface of the air electrode 55. Part) 71, and all the air electrode side current collectors 37 and the air electrodes 55 are bonded by the air electrode bonding layer 71.

  That is, each air electrode side current collector 37 is in contact with the surface of the air electrode 55 via each air electrode bonding layer 71. Accordingly, each air electrode bonding layer 71 is in contact with a part of the surface of the air electrode 55, and the surface of the air electrode 55 is partially exposed to the air flow path 35.

  Examples of the material constituting the air electrode bonding layer 71 include a conductive spinel oxide. This conductive spinel oxide is a metal oxide having a spinel crystal structure, and is not particularly limited as long as it has conductivity and forms a porous structure.

The conductive spinel oxide is an oxide represented by a composition formula of AB ₂ O ₄ and has two sites where cations called A site and B site are arranged in the crystal. Examples of the metal element indicating the A site and the B site include Cu, Mn, Co, Fe, Cr, Ni, and Zn. As the conductive spinel oxide, CuMn ₂ O ₄ , MnCo ₂ O ₄ , CoMn ₂ O ₄ , MnFe ₂ O ₄ , ZnMn ₂ O ₄ , CuFe ₂ O ₄ , CuFe ₂ O ₄ , NiMn ₂ O ₄ , CoCr ₂ O ₄ etc. are mentioned. Among these, it is preferable that CuMn ₂ O ₄ having high conductivity is included in the air electrode bonding layer. A part of the A site and the B site may be substituted with a metal element other than the metal element.

  In the first embodiment, among the plurality of joining pieces 63a of the conductive plate 63 of the fuel electrode side current collector 41, the joining piece 63a disposed in the central portion (excluding one row on the outer periphery) is It is configured to be bonded to the fuel electrode 53 by an inner bonding layer 73 made of a material. Further, the portion of the conductive plate 63 that contacts the interconnector 17b is all joined to the interconnector 17b by an outer joining layer 75 made of a brazing material.

  Specifically, as schematically shown in FIG. 9, all of the joint pieces 63 a on the inner side except one row of the outer periphery among the plurality of joint pieces 63 a of the fuel electrode side current collector 41 in a plan view, that is, the center. All the joining pieces 63 a arranged in the portion (shown in gray in FIGS. 9 and 7) are joined to the fuel electrode 53 by the inner joining layer 73.

  The inner bonding layer 73 is formed over the entire surface of the region R1, and a part thereof is a first bonding portion 73a (see FIG. 8). That is, the first joint portion 73a is a portion of the inner joint layer 73 that is sandwiched between the fuel electrode 53 and the joint piece 63a.

  Here, the outer periphery of the plurality of joining pieces 63a (and hence the first joining portion 73a) in the central portion is an outer periphery G1 indicated by a broken line in FIG. In addition, the range of this outer periphery G1 is a square of 84 mm long × 84 mm wide, for example.

  The range in which the inner bonding layer 73 is formed may be the region R1 as described above. For example, the inner bonding layer 73 may be a range on the outer peripheral side from the outer periphery G1 and not in contact with the outermost bonding piece 63a. The inner bonding layer 73 may be formed only on the first bonding portion 73a.

  Further, the outer periphery G2 is set on the outer periphery side of the outer periphery G1, which is a range where the joining piece 63a of the fuel electrode side current collector 41 contacts the fuel electrode 53. The range of the outer periphery G2 is, for example, a square of 92 mm long × 92 mm wide.

Ni, Pt, Ni—Pt, or the like can be used as a material constituting the inner bonding layer 73 (and hence the first bonding portion 73a).
On the other hand, Pt, Ag, Pt—Ag, or the like can be adopted as a material constituting the outer bonding layer 75.

  As described above, in the first embodiment, as shown in FIG. 9, the outer periphery G1 of the region R1 in which the first joint portion 73a (the gray portion in the figure) to which the joint piece 63a is joined is arranged in plan view. Is formed inside the outer periphery G2 of the region R2 in which the fuel electrode side current collector (first current collector) 41 is disposed, and the air electrode side current collector 37 (therefore, the air electrode bonding layer 71: second). It is formed on the inner side of the outer periphery G3 of the region R3 where the joint portion is disposed.

  In plan view, the area S1 of the region R1 where the first joint 73a is disposed and the region R4 where the air electrode side current collector 37 (second current collector) is disposed (that is, the air electrode bonding layer 71 (first The area ratio (S1 / S2) to the area S2 of the region R3) where the two junctions) are arranged is in the range of 0.05 <S1 / S2 <0.92.

  Furthermore, in plan view, the outer periphery G1 of the region R1 in which the first joint portion 73a is disposed is all the outer periphery G4 of the region R4 in which the air electrode side current collector 37 (second current collector) is disposed. It is formed inside 0.4 cm or more over the circumference.

e) Next, a method for manufacturing the fuel cell stack 1 will be described.
[Manufacturing process of each member]
First, for example, a plate material made of SUS430 was punched out to produce the interconnector 17, the fuel electrode frame 27, the separator 25, and the end plates 3 and 5.

An air electrode side current collector 37 was formed on one surface of the interconnector 17 and the end plate 3 by cutting.
Further, the frame-shaped air electrode insulating frame 23 and the fuel electrode insulating frame 29 shown in FIG. 3 were manufactured by punching or grooving a mica sheet made of known soft mica.

[Manufacturing Process of Fuel Cell Single Cell 15]
The fuel cell single cell 15 was manufactured according to a conventional method.
Specifically, first, in order to form the porous fuel electrode 53, for example, 40 to 70 parts by mass of yttria-stabilized zirconia (YSZ) powder having an average particle size of 0.5 to 5 μm and an average particle size of 0. A fuel electrode paste was prepared using a material comprising 40 to 70 parts by mass of a nickel oxide powder of 5 to 5 μm and a binder solution. Then, using this fuel electrode paste, a fuel electrode green sheet was produced by a known doctor blade method.

  Moreover, in order to produce the solid electrolyte layer 51, for example, a solid electrolyte paste was produced using a material composed of a YSZ powder having an average particle size of 0.5 to 3 μm and a binder solution. And using this solid electrolyte paste, the solid electrolyte green sheet was produced by the doctor blade method.

  Next, a solid electrolyte green sheet was laminated on the fuel electrode green sheet. And the laminated body was sintered by heating at 1200-1500 degreeC for 1 to 10 hours, and the sintered laminated body was formed.

Further, in order to form the porous air electrode 55, a material composed of La _1-x Sr _x Co _1-y Fe _y O ₃ powder having an average particle diameter of _{1 to 4} μm and a binder solution is used. A paste was prepared.

  Next, an air electrode paste was printed on the surface of the solid electrolyte layer 51 in the sintered laminate. Then, the printed air electrode paste was baked at 900 to 1200 ° C. for 1 to 5 hours so as not to become dense by baking, and the air electrode 55 was formed.

Thereby, the fuel cell single cell 15 was completed. A separator 25 was fixed to the single fuel cell 15 by brazing.
[Manufacturing Process of Air Electrode Bonding Layer 71]
A spinel material-based air electrode bonding layer paste containing Mn was applied to the surface (bottom surface) of the air electrode side current collector 37 on the air electrode 55 side by screen printing or the like. The air electrode bonding layer paste may be similarly applied to the surface of the air electrode 55 facing the air electrode side current collector 37 by screen printing or the like. Then, it was made to dry for 30 minutes at the temperature (80-120 degreeC) which the adhesiveness of an air electrode joining layer paste is not lost.

[Manufacturing Process of Inner Bonding Layer 73 and Outer Bonding Layer 75]
An inner bonding layer paste containing NiO was applied to the entire surface of the fuel electrode 53 by screen printing or the like within the range of the outer periphery G1. Then, it was dried for 30 minutes at a temperature (80 to 120 ° C.) at which the adhesiveness of the inner bonding layer paste is not lost.

  The outer bonding layer paste containing Ag is applied to the entire surface of the interconnector 17 on the fuel electrode 53 side by screen printing or the like within a range of the outer periphery G2 where the fuel electrode side current collector 41 is disposed (in plan view). It was applied to. Then, it was dried for 30 minutes at a temperature (80 to 120 ° C.) at which the adhesiveness of the outer bonding layer paste was not lost.

[Manufacturing process of fuel cell stack 1]
Next, the above-mentioned members (applied with the air electrode bonding layer paste, the inner bonding layer paste, and the outer bonding layer paste) are laminated in a desired number of stages as shown in FIG. 3, and both ends in the lamination direction Then, the end plates 3 and 5 were laminated to form a laminated body.

And while inserting the bolt 11 in the through-hole 9 of this laminated body, the nut 13 was screwed and tightened to each bolt 11, and the laminated body was pressed and integrated and fixed.
Next, this laminate is heated in an oxidizing atmosphere to join the air electrode side current collector 37 and the air electrode 55 with the air electrode bonding layer 71, and the fuel electrode 53 and the fuel electrode side current collector 41. While being joined by the inner joining layer 73, the fuel electrode side current collector 41 and the interconnector 17 b were joined by the outer joining layer 75.

  As the conditions for the oxidation treatment, the laminate is put in an electric furnace, the fuel gas is supplied to the fuel flow path 39 in the range of 300 to 900 ° C., and the oxidant having an oxygen concentration of 15 to 100% is supplied to the air flow path 35. The method of hold | maintaining for 2 to 10 hours, flowing gas is mentioned.

As a result, the fuel cell stack 1 of the first embodiment was completed.
f) Next, effects of the first embodiment will be described.
In the first embodiment, the outer periphery G1 of the region R1 in which the first joint portion 73a is disposed is formed inside the outer periphery G2 of the region R2 in which the fuel electrode side current collector 41 is disposed in plan view. The air electrode bonding layer 71 is formed on the inner side of the outer periphery G3 of the region R3.

  Accordingly, when the temperature of the fuel cell stack 1 is lowered from a high temperature during operation (for example, 700 ° C. to 1000 ° C.) to a low temperature such as room temperature (for example, 25 ° C.), the interconnector 17 is bent and the outer peripheral portion When the air electrode side current collector 37 is subjected to thermal stress such that the air electrode side current collector 37 is peeled off from the air electrode 55, the outer peripheral portion without the first joint 73 a of the fuel electrode side current collector 41 is in contact with the fuel electrode 53. Since it is not joined, it is possible to suppress the pulling of the fuel cell single cell 15 between the air electrode side current collector 37 and the fuel electrode side current collector 41, and the air electrode 55 or the air electrode joining layer 71. Breakage or peeling (bonding part is peeled off) or the solid electrolyte layer 51 is hardly damaged.

  Therefore, even when the temperature rises again and the curvature of the interconnector 17 returns, the air electrode side current collector 37, the air electrode 55, and the air electrode 55 and the solid electrolyte layer 51 remain bonded. The high electrical connection (conductivity) between the air electrode side current collector 37 and the air electrode 55 and between the air electrode 55 and the solid electrolyte layer 51 can be maintained. In other words, it is possible to prevent the electrical connection from changing before the thermal stress is generated and after the thermal stress is generated.

  Further, the fuel electrode side current collector 41 has a larger elastic amount than the interconnector 17 (and hence the air electrode side current collector 37). Therefore, the fuel electrode side current collector 41 can follow the deformation of each member due to thermal stress (a reduction in the area of electrical connection between the fuel electrode side current collector 41 and the fuel electrode 53 can be suppressed). Therefore, high electrical connection between the fuel electrode side current collector 41 and the fuel electrode 53 can be ensured.

  Thus, in the first embodiment, the air electrode side current collector 37 is peeled off from the air electrode 55 even when a heat cycle is applied in which the temperature rises from room temperature to a high temperature during operation and then decreases to room temperature again. Moreover, since it can suppress that the air electrode side electrical power collector 37 peels from the solid electrolyte layer 51 with a part of air electrode 55, always high electroconductivity is securable. Therefore, there is a remarkable effect that power generation performance can be secured stably.

  In order to maintain the power generation capacity high, it is preferable that the area where the air electrode side current collector 37, the air electrode 55, and the air electrode 55 and the solid electrolyte layer 51 are joined is large. As in the embodiment, even if a heat cycle is applied, the area where the air electrode side current collector 37, the air electrode 55, and the air electrode 55 and the solid electrolyte layer 51 are joined does not decrease, thereby reducing the power generation performance. It can be maintained stably.

  In the first embodiment, the outer periphery G1 of the region R1 in which the first joint portion 73a is disposed is 0. 0 over the entire periphery with respect to the outer periphery G4 of the region R4 in which the air electrode current collector 37 is disposed. It is formed inside 4 cm or more.

  Therefore, also from this point, even when the thermal cycle is applied and the interconnector 17 is curved, the air electrode side current collector 37, the air electrode 55, the air electrode 55, and the solid electrolyte layer 51 are further separated. It is difficult to maintain power generation performance stably.

The region R1 in which the first joint portion 73a is disposed may be formed on the inner side by 0.4 cm or more over the entire circumference with respect to the region R2 in which the fuel electrode side current collector 41 is disposed.
[Second Embodiment]
Next, the second embodiment will be described, but the description of the same content as the first embodiment will be omitted.

In addition, the same number is attached | subjected and demonstrated to the structure similar to 1st Embodiment.
The fuel cell stack according to the second embodiment is different from each other in the above-described regions.
As shown in FIG. 10A (plan view), in the second embodiment, the outer periphery G3 of the region R3 where the air electrode side current collector 37 is disposed is a square, and the fuel electrode side current collector 41 is The outer periphery G2 of the rectangular region R2 to be arranged is inside the outer periphery G3.

The outer periphery G1 of the rectangular region R1 where the inner bonding layer 73 (and hence the first bonding portion 73a) of the fuel electrode side current collector 41 is disposed is the inner side of the outer periphery G2.
The second embodiment also has the same effect as the first embodiment.

  Note that the inner bonding layer 73 may be formed on the entire surface of the region R1 (gray portion in the drawing), or the inner bonding layer 73 may be dispersed and formed only on the first bonding portion 73a. Good (hereinafter the same applies to other examples).

  Further, it is possible to adopt a configuration that is made of Ni cermet or the like instead of the fuel electrode side current collector 41 as in the first embodiment and is in contact with the fuel electrode 53 and the interconnector 17 over the entire surface in the thickness direction. In this case, the inner bonding layer 73 is formed over the entire gray portion.

  In the first embodiment, the fuel electrode side current collector 41, which is the first current collector, has elasticity, but the second current collector may be peeled off from the second electrode side, The first current collector does not need to have elasticity in that the current collector can be prevented from peeling from the solid electrolyte layer 51 side together with a part of the second electrode.

However, since the first current collector has elasticity, even when a thermal stress is applied to the fuel cell stack 1 by a thermal cycle, the first current collector (first embodiment) is caused by elastic deformation of the spacer 61. In the embodiment, the amount of elasticity of the “fuel electrode side current collector 41”) is larger than that of the second current collector (“air electrode side current collector 37” in the first embodiment). As a result, electrical connection can be more preferably secured (hereinafter, the same applies to other embodiments).
[Third Embodiment]
Next, the third embodiment will be described, but the description of the same contents as the first embodiment will be omitted.

In addition, the same number is attached | subjected and demonstrated to the structure similar to 1st Embodiment.
The fuel cell stack according to the third embodiment is different from each other in the above-described regions.
As shown in FIG. 10B (plan view), in the third embodiment, the outer periphery G3 of the region R3 where the air electrode side current collector 37 is disposed is a square, and the fuel electrode side current collector 41 is The outer periphery G2 of the square region R2 to be arranged is inside the outer periphery G3.

The outer periphery G1 of the rectangular region R1 where the inner bonding layer 73 (and hence the first bonding portion 73a) of the fuel electrode side current collector 41 is disposed is the inner side of the outer periphery G2.
Here, in the region R1, the inner bonding layer 73 is formed on the entire surface of the strip-shaped portion (gray portion in the figure).

The third embodiment also has the same effect as the first embodiment.
[Fourth Embodiment]
Next, the fourth embodiment will be described, but the description of the same contents as the first embodiment will be omitted.

In addition, the same number is attached | subjected and demonstrated to the structure similar to 1st Embodiment.
The fuel cell stack according to the fourth embodiment is different from each other in the above-described regions.
As shown in FIG. 10C (plan view), in the fourth embodiment, the outer periphery G3 of the region R3 where the air electrode side current collector 37 is disposed is a square, and the fuel electrode side current collector 41 is The outer periphery G2 of the square region R2 to be arranged is inside the outer periphery G3.

The outer periphery G1 of the square region R1 where the inner bonding layer 73 (and hence the first bonding portion 73a) of the fuel electrode side current collector 41 is disposed is the inner side of the outer periphery G2.
Here, in the region R1, the inner bonding layer 73 is formed on the entire surface of the frame-shaped portion having a predetermined width (the gray portion in the figure).

The fourth embodiment also has the same effect as the first embodiment.
[Fifth Embodiment]
Next, the fifth embodiment will be described, but the description of the same contents as the first embodiment will be omitted.

In addition, the same number is attached | subjected and demonstrated to the structure similar to 1st Embodiment.
The fuel cell stack according to the fifth embodiment is different from each other in the above-described regions.
As shown in FIG. 10D (plan view), in the fifth embodiment, the outer periphery G3 of the region R3 where the air electrode side current collector 37 is disposed is a square, and the fuel electrode side current collector 41 is The outer periphery G2 of the square region R2 to be arranged is inside the outer periphery G3.

  The outer periphery G1 of the square region R1 where the inner bonding layer 73 (and hence the first bonding portion 73a) of the fuel electrode side current collector 41 is disposed is the inner side of the outer periphery G2. The outer periphery G1 has a shape in which a plurality of circles are bundled with strings (lines) from the outside (a shape in which a corner portion is a part of the circumference).

Here, in the region R1, the inner bonding layer 73 is formed on the entire surface of the plurality of circles (gray portions in the figure).
The fifth embodiment also has the same effect as the first embodiment.
[Sixth Embodiment]
Next, although the sixth embodiment will be described, description of the same contents as those of the first embodiment will be omitted.

In addition, the same number is attached | subjected and demonstrated to the structure similar to 1st Embodiment.
The fuel cell stack according to the sixth embodiment is different from each other in the above-described regions.
As shown in FIG. 10E (plan view), in the sixth embodiment, the outer periphery G3 of the region R3 where the air electrode side current collector 37 is disposed is a square, and the fuel electrode side current collector 41 is The outer periphery G2 of the square region R2 to be arranged is inside the outer periphery G3.

The outer periphery G1 of one circular region R1 where the inner bonding layer 73 (and hence the first bonding portion 73a) of the fuel electrode side current collector 41 is disposed is the inner side of the outer periphery G2.
Here, the inner bonding layer 73 is formed on the entire surface of the circle which is the region R1 (gray portion in the figure).

The sixth embodiment also has the same effect as the first embodiment.
[Seventh Embodiment]
Next, the seventh embodiment will be described, but the description of the same contents as the first embodiment will be omitted.

The fuel cell stack according to the seventh embodiment is different in the material constituting the air electrode bonding layer.
a) In the seventh embodiment, the air electrode bonding layer 71 is made of a silver palladium alloy (palladium content: 1 to 10 mol).

When the air electrode bonding layer 71 is formed, a vehicle is added to a powder of silver palladium alloy (Ag—Pd) to produce an air electrode bonding layer paste.
Next, the air electrode bonding layer paste is applied to the tip of the air electrode side current collector 37.

Next, after the air electrode bonding layer paste is dried, the air electrode 55 and the air electrode side current collector 37 are bonded by the air electrode bonding layer 71 as in the first embodiment.
The seventh embodiment also has the same effects as the first embodiment.

b) As a modification, the air electrode bonding layer 71 may be made of a perovskite-based (for example, LSCF + Cu) conductive bonding agent.
For example, 80 parts by weight of conductive perovskite oxide coarse particles having an average particle diameter of 5 μm, 10 parts by weight of conductive perovskite oxide coarse particles having an average particle diameter of 0.5 μm, and an average particle diameter as a sintering aid 1 part of Cu powder of 1 μm is mixed with 10 parts by weight to prepare 100 g of mixed powder.

As the conductive perovskite oxide, (La, Sr) (Co, Fe) O ₃ (ie, LSCF) is used for both coarse particles and fine particles.
To this mixed powder, a vehicle in which 60 g of etosel and 20 g of butyl carbitol are mixed is added to prepare an air electrode bonding layer paste.

Next, the air electrode bonding layer paste was applied to the tip of the air electrode side current collector 37.
Next, after the air electrode bonding layer paste is dried, the air electrode 55 and the air electrode side current collector 37 are bonded by the air electrode bonding layer 71 as in the first embodiment.

This modification also has the same effect as the first embodiment.
In addition, as a metal which is a sintering aid, Cu, Mn, Fe, Mo, Co, Zn, Ni, or alloys thereof can be employed. Among these, a simple substance or an alloy containing Cu and / Mn is preferable.
[Eighth Embodiment]
Next, although an eighth embodiment will be described, description of the same contents as those of the first embodiment will be omitted.

The fuel cell stack according to the eighth embodiment is opposite to the first embodiment in the configuration of the air electrode side current collector and the fuel electrode side current collector.
As shown in FIG. 11, in the eighth embodiment, the air electrode side current collector having the same structure as the fuel electrode side current collector 41 of the first embodiment is provided on the air electrode 55 side of the single fuel cell 15. A plurality of 101 are arranged.

  Of the air electrode side current collector 101, the one in the outer periphery G1 is joined to the air electrode 55 by the inner joining layer 103 (having the same structure as that of the first embodiment). It is joined to the inner surface of the interconnector 17 within the outer periphery G2 by the outer joining layer 105 (which has the same structure as the form). The inner surface (on the air electrode 55 side) of the interconnector 17 has a flat plate shape.

  On the other hand, the fuel electrode side current collector 107 having the same structure as the air electrode side current collector 37 of the first embodiment is disposed on the fuel electrode 53 side of the fuel cell single cell 15. The fuel electrode side current collector 107 is joined to the fuel electrode 53 by a fuel electrode joining layer 109 (having the same structure as the air electrode joining layer of the first embodiment).

In the eighth embodiment, the structure of being electrically connected to the fuel electrode 53 side and the air electrode 55 side is different from that of the first embodiment, but the interconnector 17 having the fuel electrode side current collector 107, etc. Even when is curved, the same effects as those of the first embodiment can be obtained.
<Experimental example>
Next, experimental examples conducted for confirming the effects of the present invention will be described.

In this experimental example, a computer simulation was performed on the fuel cell stack having the same configuration as that of the first embodiment under the following conditions (configuration conditions and operation conditions).
The configuration of the fuel cell stack is the same as that of the first embodiment (the power generation unit has a configuration in which, for example, 20 stages are stacked).

  The operating condition of the fuel cell stack was continuous energization durability (5000 Hr). The operating temperature was 700 ° C., the supply amount of fuel gas (specifically hydrogen) was 10 L / min, and the supply amount of oxidant gas (specifically air) was 35 L / min.

  When the fuel cell stack is brought to room temperature (25 ° C.) after operating under the above conditions, the extent of the thickness direction in the lateral direction (left-right direction in FIG. 8) of the interconnector (IC) The deformation amount (IC deformation amount) of whether to deform was examined.

  The result is shown in FIG. The vertical axis in FIG. 12 is the IC deformation amount [μm], and the horizontal axis is the IC horizontal length [mm] (that is, the length from the left end in FIG. 8). The upper IC is the upper (air electrode side) interconnector in the central power generation unit in the stacking direction of the fuel cell stack, and the lower IC is the lower (fuel electrode side) interconnect in the power generation unit. It is a connector.

  As is clear from FIG. 12, the portion where the deformation of the interconnector is small (the central portion in the left-right direction) is, for example, a range in which the contact between the air electrode side current collector and the air electrode is maintained. Even if is added, for example, it is considered that the air electrode side current collector and the air electrode do not peel off. In addition, it is thought that the air electrode side current collector and the air electrode are separated, for example, at locations where the outer periphery is greatly deformed (on both sides of the central portion in the left-right direction).

  That is, it can be seen that the amount of deformation of the interconnector is larger toward the outer peripheral side of the interconnector in the planar direction. Therefore, when the fuel electrode and the fuel electrode side current collector are joined on the outer peripheral side of the interconnector where the amount of deformation of the interconnector increases, it is considered that the air electrode side current collector and the air electrode are separated. . Conversely, if the fuel electrode side current collector and the fuel electrode are not joined by the fuel electrode joining layer on the outer peripheral side of the interconnector in the planar direction, even if the interconnector is deformed, the fuel electrode side current collector It is considered that force pulling hardly occurs between the air electrode side current collector and the air electrode side current collector, and the air electrode side current collector and the air electrode do not peel off.

The range of the central portion is 2 cm long × 2 cm wide = 4 cm ² (in plan view).
As mentioned above, although embodiment etc. of this invention were described, this invention is not limited to the said embodiment etc., A various aspect can be taken.

  (1) For example, in each of the above-described embodiments, the interconnector and the air electrode side current collector have an integral structure, but the interconnector and the air electrode side current collector are configured as separate members, You may join by material etc. For example, a block-like or long current collector may be joined to one surface of the flat interconnector.

  (2) For example, a material such as a non-buckling sponge may be used for the spacer etc. as the fuel electrode side current collector.

DESCRIPTION OF SYMBOLS 1 ... Fuel cell stack 3, 5 ... End plate 7 ... Power generation unit 15 ... Fuel cell single cell 17, 17a, 17b ... Interconnector 37, 103 ... Air electrode side collector 41, 107 ... Fuel electrode side collector 51 ... Solid electrolyte layer 53 ... Fuel electrode 55 ... Air electrode 63a ... Junction pieces 71, 105 ... Air electrode joining layer (second joining portion)
73 ... Fuel electrode joining layer 73a ... First joining portion

Claims (4)

A flat plate type fuel cell unit cell having a first electrode on one side of a flat solid electrolyte and a second electrode on the other side;
A first current collector electrically connected to the first electrode;
A second current collector electrically connected to the second electrode;
A first joint for joining the first electrode and the first current collector;
A second joint for joining the second electrode and the second current collector;
In a fuel cell stack with
The outer periphery (G1) of the region (R1) in which the first joint portion is disposed is formed inside the outer periphery (G2) of the region (R2) in which the first current collector is disposed, and the second A fuel cell stack, wherein the fuel cell stack is formed on the inner side of the outer periphery (G3) of the region (R3) where the joint portion is disposed.   The outer periphery (G1) of the region (R1) in which the first joint portion is disposed is 0.4 cm or more over the entire periphery with respect to the outer periphery (G4) of the region (R4) in which the second current collector is disposed. The fuel cell stack according to claim 1, wherein the fuel cell stack is formed inside.   The first electrode is a fuel electrode, the second electrode is an air electrode, the first current collector is a fuel electrode side current collector, and the second current collector is an air electrode side current collector. The fuel cell stack according to claim 1 or 2. The first current collector includes a spacer having elasticity and a conductive member having a conductor,
The said spacer is pinched | interposed into the said electrically-conductive member, The said electrically-conductive member and the said 1st electrode are joined via the said 1st junction part, The any one of Claims 1-3 characterized by the above-mentioned. The fuel cell stack described in 1.