JP2010073631A - Fuel cell power generation unit and fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power generation unit capable of joining metal cases together through a soft adhesive layer and improving durability as a fuel cell stack, and a fuel cell stack consisting of such a power generation unit. <P>SOLUTION: In the power generation unit 1 including a cell inside a metal case 2 consisting of a first metal plate 3 and a second metal plate 4, fuel gas and oxidized gas are separated as well as a flat plate part of the second metal plate 4 functioning as a conductive passage is separated as an electric conductive plate 4e to electrically insulate from an outer frame part 4b being as an adhesive site between power generation units. By laminating a plurality of such power generation units 1, metal cases 2 are adhered with each other with the use of fully-soft metal wax material to make a fuel cell stack. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell power generation unit formed by enclosing a solid oxide fuel cell in a metal case, and a fuel cell stack formed by adhering such power generation units in a stacked state. The present invention relates to an insulating structure and a technique for bonding such power generation units.

A solid oxide fuel cell (SOFC) has a structure in which a solid electrolyte having oxide ion conductivity such as yttria-stabilized zirconia is used as an electrolyte, and electrodes having gas permeability are arranged on both sides thereof. It is known as a battery that operates at a high temperature close to 1000 ° C.
However, in recent years, with the improvement in cell performance due to improvements in electrolyte characteristics, the operating temperature has been lowered, and sufficient power generation output has been obtained even at 600 to 800 ° C.

When operation at such a temperature becomes possible, it is becoming common to use a heat-resistant metal material instead of a conventional ceramic material for the peripheral members of a fuel cell such as a separator.
The heat-resistant metal material mentioned here is an alloy containing chromium and means stainless steel or nickel-based alloy. Specifically, ferritic stainless steel, Inconel (registered trademark), Hastelloy (registered trademark) ) And the like.

  In such a low temperature operation type solid oxide fuel cell, a power generation unit (also referred to as a cassette) having a separator function and including a cell as a power generation element in a heat resistant metal case forming a gas flow path, These are stacked to form a stack.

For joining between metal members in such a single cell or between a metal member and a ceramic member (electrolyte membrane), if necessary, a sealing material made of glass mixed with ceramic powder or metal powder, or if necessary Patent Documents 1 and 2 disclose the use of a sealing material made of a metal brazing material including ceramics.
JP 2004-39573 A JP 2004-39574 A

However, various performances corresponding to the parts are required for the inside of the power generation unit described above and the material for bonding the power generation units in the fuel cell stack. For example, in order to prevent the metal case and the cell electrode from being short-circuited in the joining of the power generation units in the battery stack, it is necessary to electrically insulate the power generation units. Electrical insulation is required.
Therefore, the metal brazing material described in the above cited reference 2 cannot be used, and a glass-based material represented by the glass sealing material described in the cited reference 1 is used for such joining. Will be.

On the other hand, since the battery stack is formed by stacking power generation units in multiple stages, high dimensional accuracy is required for each metal case constituting each power generation unit, and it becomes a rigid body. In addition, the metal case is required to have rigidity because the power generation units need to be pressed against each other in order to improve the current collecting performance.
However, the glass-based material used for joining the power generation units is essentially a fragile material and lacks flexibility, so if the metal case is deformed thermally or mechanically, it can follow this. In the case of a metal case with high rigidity, there is a problem that this tendency becomes remarkable.

  The present invention has been made in view of the above problems in a fuel cell stack in which a plurality of power generation units each containing cells in a metal case are stacked and the metal cases are bonded together. And the purpose is to be able to join between metal cases through a flexible adhesive layer, and to improve the durability as a stack, and such a power generation unit in a laminated state It is an object of the present invention to provide a fuel cell stack in which a plurality are adhered.

  As a result of intensive studies to achieve the above object, the present inventors have conducted electrical continuity between the separator portion of the metal case that functions as a conduction path between cells and the outer frame portion to which the metal cases are bonded. The inventors have found that the above object can be achieved by blocking, and have completed the present invention.

  The present invention is based on the above knowledge, and the fuel cell power generation unit of the present invention includes a first metal plate that supports a cell and a second metal plate that separates a fuel gas and an oxidizing gas, The cell is encased in a metal case provided with these gas flow paths, and the second metal plate is provided with an electric conduction plate serving as a current-carrying path at the center thereof, and the electric conduction plate It is characterized by being electrically insulated from the outer frame portion provided with the manifold portion.

  Further, the fuel cell stack of the present invention includes a plurality of the power generation units of the present invention stacked, and the power generation units are connected to each other through an adhesive layer having a lower rigidity than the first and second metal plates constituting the metal case. It is bonded.

  In the fuel cell stack manufacturing method of the present invention, a silver brazing filler metal layer is formed on the front and / or back surface of the outer frame portion of the metal case of the power generation unit, and a plurality of power generation units each having the silver brazing filler metal layer are provided. Heating and pressing are performed with the units stacked.

  According to the present invention, in a power generation unit including a cell in a metal case composed of a first metal plate functioning as a cell support plate and a second metal plate functioning as a separator, the second metal plate Is provided with an electrically conductive plate serving as an energization path at the center thereof, which is electrically insulated from the outer frame portion. Therefore, it is not necessary to use an insulating glass-based material for bonding the metal cases when laminating the power generation units, and cracking and peeling are prevented by using other ductile materials such as metal brazing materials. This can improve the durability of the stack.

  Hereinafter, the fuel cell power generation unit of the present invention and the fuel cell stack in which the fuel cell power generation unit is laminated will be described more specifically and in detail. In the present specification, “%” means mass percentage unless otherwise specified.

  The fuel cell power generation unit of the present invention includes a first metal plate that supports the cell and a second metal plate that separates the fuel gas and the oxidizing gas, and the flow paths of the fuel gas and the oxidizing gas are respectively provided. The cell is included in a metal case provided. And as above-mentioned, a 2nd metal plate becomes an electricity supply path | route, equips the center part with the electrical-conductive board which functions also as a separator, and this electrical-conductive board is electrically from the outer frame part provided with the manifold part. Since it is insulated, it is not necessary to insulate the metal cases when bonding the power generation units.

  That is, in a general power generation unit, the partition wall functioning as a separator is also used as a current collecting path. Therefore, when a continuous second metal plate is used as a separator, the metal cases are electrically connected to each other. It is necessary to prevent short circuit of the cell electrode by electrically insulating. On the other hand, in the present invention, since the central portion (electrically conductive plate) of the second metal plate serving as the gas partition wall and the current collecting path is insulated from the outer frame portion serving as the bonding site, Whether or not there is conductivity in the bonding is not questioned, and a material having excellent ductility can be used instead of the brittle glass system.

For example, as a glass-based adhesive material, the Young's modulus of BCAS (BaO—CaO—Al ₂ O ₃ —SiO ₂ ) glass is 230 GPa, whereas the Young's modulus of a metal brazing material such as silver-copper brazing is about 70 GPa. About 1/3, the metal brazing material is much less rigid than the glass material and exhibits high ductility.
Therefore, by applying such ductile metal brazing material for bonding between power generation units, the adhesive layer can follow deformations caused by temperature rise and fall of the metal case and vibration due to impact, etc., and cracking and peeling Can be maintained, and the gas sealing property and current collecting property can be maintained for a long time, and the durability of the stack is improved.

In the power generation unit of the present invention, a cell as a power generation element basically has a three-layer structure in which a fuel electrode and an air electrode are formed on both sides of a solid electrolyte. As an electrolyte material, for example, YSZ (yttria stabilized zirconia) ), SDC (samaria doped ceria), SSZ (scandia stabilized zirconia), LSGM (lanthanum is a rate), and the like.
Further, as the fuel electrode material, for example, Ni-YSZ, Ni-SDC, Ni-SSZ, etc., and as the air electrode material, electrons such as LSM (LaSrMnO), SSC (SrSmCoO), LSC (LaSrCoO), LSCF (LaSrCoFeO), etc. An oxygen ion conductive oxide or a metal material such as Pt or Ag can be mentioned, but is not particularly limited thereto.

  As the material of the first and second metal plates constituting the metal case, stainless steel, nickel-base alloy, Inconel, Hastelloy, or other heat-resistant metal can be used. It is desirable to use ferritic stainless steel from the viewpoint of the closeness of the coefficient of thermal expansion to the material constituting the cell. Specifically, SUS430 steel, Fe-22Cr steel, or the like can be used.

In addition, when laminating the power generation units, the metal brazing material as described above can be used as a material for bonding the metal cases to each other, and as long as it is more ductile than the glass-based material, there are no particular limitations on the types and components thereof. Absent.
The metal brazing material may be a material that can provide an adhesive layer having lower rigidity (for example, Young's modulus of ferritic stainless steel is about 200 GPa) than the materials of the first and second metal plates constituting the metal case. Desirably, for example, a silver brazing material can be used. Specifically, a silver-copper brazing material in which 2 to 5% of Cu is added to Ag or an Ag alloy in which a small amount of titanium, nickel, or zirconium is added as a third element can be used as the silver-based brazing material.

  On the other hand, as an adhesive used for directly joining a metal electric conductive plate to the insulating bonding portion inside the power generation unit, that is, the outer frame portion of the second metal plate, a cell or a metal plate (ferritic stainless steel) Therefore, it is desirable to use the BCAS glass described above.

In the power generation unit of the present invention, as described above, the central portion of the second metal plate functioning as the gas partition wall and the current collecting path is separated to be an electrically conductive plate, which is insulated from the outer frame portion serving as a bonding portion. It is characterized by that.
At this time, as a specific structure for insulating the electrical conductive plate, when the electrical conductive plate is made of metal, an electrical insulating adhesive layer such as the BCAS glass is formed on the outer frame portion of the second metal plate. It can be made to adhere via.

  Moreover, it is also possible to adhere | attach to the outer frame part of a 2nd metal plate through the board | plate material which has electrical insulation. At this time, since the insulation between the electrical conductive plate and the outer frame portion is ensured by the interposition of the plate material, the insulation between the plate material and the outer frame and the adhesion between the plate material and the electrical conductive plate is always required. Not. Accordingly, it is desirable to use a highly ductile material such as a metal brazing material, but there is no problem even if a glass-based material is used.

  Further, as the electrical conductive plate, a plate material made of an electrically insulating material having a large number of through holes is used. By filling the through holes with a conductive material such as metal, the electrical conductivity in the plate thickness direction is improved. It can also be ensured. At this time, a high ductility material such as a metal brazing material can be used for adhesion to the outer frame portion of the electric conductive plate as long as it does not contact the through-hole portion. In addition, when filling the through hole with the conductive material, it is necessary to close the through hole so as not to cause gas permeation.

  A metal body having gas permeability such as a porous metal, a metal mesh, or a felt-like metal (metal wool) can be electrically connected to the electric conductive plate. Such a metal body is interposed between the electric conductive plate and the cell electrode, and functions as a current collector without hindering supply of fuel gas or oxidizing gas to the cell.

In the power generation unit of the present invention, a cutout portion can be provided in the outer frame portion of the first metal plate, the second metal plate, or both metal plates, thereby reducing the rigidity of the metal case and making it more flexible. Structure. The notch serves as a relief of thermal stress at the time of raising and lowering temperature and mechanical stress due to deformation of the case, the stress applied to the bonded portion is relaxed, and the durability of the stack can be improved.
Note that the leakage of the fuel gas and the oxidizing gas from the notch can be blocked by a thin metal plate or the like as necessary. At this time, for example, when air is used as the oxidizing gas, air leakage does not necessarily have to be blocked.

  A fuel cell stack according to the present invention includes a plurality of the fuel cell power generation units stacked, and the power generation units are made of an adhesive layer having a lower rigidity than the first and second metal plates constituting the metal case, for example, a metal brazing material. It is bonded through an adhesive layer.

In the fuel cell stack using the power generation unit provided with the notch in the outer frame portion of the metal case, at least one of the first and second metal plates provided with the notch in a state where the units are similarly bonded to each other. It is desirable to adhere a metal thin plate to the outer frame portion with a similar adhesive layer. This prevents fuel gas and oxidizing gas from leaking from the notch.
The metal thin plate is used so that the adhesion of the metal case is not impaired by this adhesion, and the term “thin plate” means that the metal case material is thinner than the metal case material. It is desirable to use a homogeneous metal foil.

In manufacturing the fuel cell stack of the present invention, first, a paste-like silver brazing material is applied to the front or back surface of the outer frame portion of the metal case that serves as an adhesion site of the power generation unit, and if necessary, both surfaces thereof. Alternatively, a brazing filler metal layer is formed by attaching a thin silver brazing filler metal.
Then, heating is performed in a state where a large number of power generation units having such a brazing material layer are laminated to melt the brazing material layer, and at the same time, the outer frames are brought into close contact with each other to solidify the brazing material metal in this state. Thus, the metal cases of the power generation unit can be bonded to each other.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, it cannot be overemphasized that this invention is not limited at all by such an Example.

[Example 1]
FIG. 1 shows the structure of a first metal plate constituting one of the metal cases used in the first embodiment of the fuel cell power generation unit of the present invention, and FIGS. These are a front view, a back view, and a longitudinal sectional view, respectively.
The first metal plate 3 shown in the figure has a frame shape made of ferritic stainless steel, and has a cell installation hole 3a to which a cell is attached at the center. An air hole 3c and a hydrogen hole 3d through which air as an oxidizing gas and hydrogen as a fuel gas are supplied and exhausted respectively are opened in the surrounding outer frame part 3b to form a manifold part. Moreover, the peripheral part of the cell installation hole 3a in the outer frame part 3b becomes the flat plate part 3e for adhere | attaching the cell mentioned later.

FIG. 2 shows the structure of the second metal plate constituting the other side of the metal case, and FIGS. 2A to 2C are a front view, a back view, and a longitudinal sectional view, respectively. .
The second metal plate 4 shown in the figure is also made of ferritic stainless steel, has an opening 4a in the center, and has the same outer shape as the first metal plate 3, and the same ferrite. It consists of an electrically conductive plate 4e made of a stainless steel.

The outer frame portion 4b is provided with air holes 4c and hydrogen holes 4d at positions corresponding to the first metal plate 3, and is similarly formed with a manifold portion and a central portion of the outer frame portion 4b. The peripheral edge portion of the opening 4e formed in the flat plate portion 4f.
And in the flat plate part 4f of the outer frame part 4b, the four circumferences of the said electrically conductive board 4e are adhere | attached by the insulating adhesive layer I which consists of BCAS glass, and the opening part 4a is completely plugged up.

FIG. 3 is a cross-sectional view of the power generation unit 1 in which the cell 5 is included in the metal case 2 composed of the first and second metal plates 3 and 4.
In the figure, a cell 5 has a porous fuel electrode 5a made of cermet of nickel and YSZ (yttria stabilized zirconia) as a substrate, an electrolyte layer 5b made of YSZ (yttria stabilized zirconia) thereon, and further an LSM thereon. It has a structure in which an air electrode 5c made of (lanthanum, strontium, manganate) is formed. The four circumferences of the cell 5 are bonded to the flat plate portion 3e of the first metal plate 3 constituting the metal case 2 by silver-copper brazing (Ag-5% Cu), thereby closing the cell installation holes 3a of the metal plate 3. It is attached to the state.

On the other hand, a metal body 4g made of porous metal and having gas permeability is spot-welded on the upper surface of the electric conductive plate 4e of the second metal plate 4 between the fuel electrode 5a of the cell 5 and the gas electrode 5a. Electrical continuity is ensured.
On the other hand, a metal body 4h made of the same porous metal is spot-welded to the lower surface side of the electric conductive plate 4e in the drawing, and in the laminated state of the power generation unit 1, the air electrode 5c of the adjacent unit is electrically connected. Connected.

  In the power generation unit 1, the first metal plate 3 and the second metal plate 4 are joined at the outer frame portions 3 b and 4 b by laser welding, TIG welding, or the like to form the metal case 2. .

FIG. 4 is a cross-sectional view showing the structure of a fuel cell stack 10 in which the power generation units 1 are stacked in five stages.
As shown in the figure, each power generation unit 1 is composed of a ferritic stainless steel that is a material of the metal case 2 in the outer frame portions 3b and 4b of the metal case 2 (first and second metal plates 3 and 4). They are bonded to each other by an adhesive layer D having a thickness of 50 μm made of silver-copper brazing (Ag-5% Cu, Young's modulus: about 70 GPa) having a lower rigidity than (Young's modulus: about 200 GPa).

At the upper and lower positions of the fuel cell stack 10, a positive electrode 6 a and a negative electrode for supplying / exhausting oxidizing gas (air) and fuel gas (hydrogen) to each power generation unit 1 and taking out electric power outside the stack 10. End plates 6 and 7 each having 7a are arranged.
Further, when bonding, the paste including the silver-copper brazing material is applied on the front and back surfaces of the outer frame portions 3b and 4b of the metal case 2 to be bonded portions, and the whole is heated to 950 ° C. Each power generation unit and the end plate are joined by pressurization and air cooling to room temperature.

And about the said fuel cell stack 10, after heating up to 700 degreeC with the temperature increase rate of 50 degreeC / min, the thermal cycle test which cools to room temperature was implemented, and durability of the said stack 10 was investigated.
That is, the internal resistance after 50 cycles of the above temperature increase / decrease was measured to evaluate the current collecting performance, and the presence or absence of cracks or peeling in the adhesive layer D after the 100 cycle test was investigated.

As a result, as shown in Table 1, the internal resistance of the stack 10 was as small as 80 mΩcm ² even after 50 cycles of the test, indicating excellent current collecting performance. Further, even after 100 cycles of the test, no cracking or peeling was observed in the adhesive layer D, and it was confirmed that the adhesive layer D had good durability sealability.

[Example 2]
FIG. 5 shows a second embodiment of the fuel cell power generation unit of the present invention, and FIG. 5 (a) is a sectional view thereof.
In the power generation unit 1 according to this embodiment, the cell 5 has the same structure as that of the above embodiment, and is similarly bonded to the cell installation hole 3a of the first metal plate 3 constituting the metal case 2 by means of a silver and copper solder. ing.

On the other hand, the electric conductive plate 4e in the second metal plate 4 is made of a ferritic stainless steel having a plurality of fins 4i arranged in parallel on the upper and lower surfaces, as shown in FIG. 5 (b). A gas flow path is formed between these fins 5i, and a gas flow can be formed without pressure loss.
Such an electric conductive plate 4e is bonded to the flat plate portion 4f of the second metal plate 4 via the adhesive layer D made of the same silver-copper brazing through the frame-shaped plate material 8 made of insulating ceramics. The tips of the fins 5i are attached so as to be in electrical contact with the electrodes of the cell 5, respectively. In addition, since the electrical conductive plate 4e is insulated from the outer frame portion 4b by the insulating plate material 8, it is desirable in terms of strength to use the above-mentioned metal brazing for bonding, but a glass-based material is used. You can also

Next, the above-described power generation unit 1 is stacked in five stages, and the metal cases of each unit 1 together with the end plates 6 and 7 are bonded using silver-copper brazing (Ag-5% Cu), so that FIG. A similar fuel cell stack is obtained.
As a result of performing the same durability test with a thermal cycle load, as shown in Table 1, the internal resistance of the stack was 150 mΩcm ² after the 50 cycle test, and the adhesive layer D even after the 100 cycle test. No cracking or peeling was observed, and excellent durability was confirmed.

Example 3
FIG. 6 shows a third embodiment of the fuel cell power generation unit of the present invention, and FIG. 6 (a) is a sectional view thereof.
In the power generation unit 1 according to this embodiment, the first metal plate 3 is not different from the first and second embodiments in the shape, structure, and bonding structure of the cells 5, and the description thereof is omitted.

On the other hand, the electrically conductive plate 4e in the second metal plate 4 is formed by forming a through hole 4j having a diameter of 0.5 mm on an electrically insulating flat plate with a density of 12 per cm ² , and a conductive material in the through hole 4j. 4k embedded structure.
Here, 3 mol yttria-stabilized zirconia having a thickness of 0.3 mm is used as the electrical insulating property, and nickel is used as the conductive material 4k. However, the present invention is not limited thereto, and various materials can be used.

  The electric conductive plate 4e having such a structure is bonded to the flat plate portion 4f of the second metal plate 4 at the peripheral edge portion of the electric insulating flat plate through the adhesive layer D made of the same silver-copper brazing as described above. Has been.

Then, the above-described power generation unit 1 is similarly laminated in five stages, and the metal cases of each unit 1 are bonded together with the end plates 6 and 7 using silver-copper brazing (Ag-5% Cu). A fuel cell stack as shown in Fig. 1 was obtained, and the same durability test was performed using this fuel cell stack.
As a result, as shown in Table 1, the internal resistance of the stack was 110 mΩcm ² after the 50 cycle test, and no cracking or peeling was observed in the adhesive layer D even after the 100 cycle test. Durability was confirmed.

Example 4
FIG. 7 is a cross-sectional view showing a fourth embodiment of the fuel cell power generation unit of the present invention.
In the power generation unit 1 according to this embodiment, the first metal plate 3 is not different from the first to third embodiments in the shape, structure, and bonding structure of the cells 5.

On the other hand, the second metal plate 4 is made of the same material as that of the first embodiment and has the same structure, and the electrically conductive plate 4e is similarly attached to the opening 4e. The flat plate portion 4f of the frame portion 4b is bonded by an insulating adhesive layer I made of BCAS glass.
A metal body 4g made of a nickel mesh having gas permeability is spot-welded on the upper surface of the electric conductive plate 4e in the drawing so as to ensure electrical continuity with the fuel electrode of the cell 5. Yes. Further, a metal body 4h made of a stainless steel mesh and similarly gas permeable is spot-welded on the lower surface side of the electric conduction plate 4e in the figure, and in the stacked state of the power generation unit 1, the adjacent unit It is electrically connected to the air electrode.

Then, the power generation unit 1 having the above structure is similarly laminated in five stages, and the metal cases of each unit 1 are bonded together with the end plates 6 and 7 using silver copper brazing (Ag-5% Cu). A fuel cell stack as shown in FIG. 4 was obtained, and the same durability test was performed using this fuel cell stack.
As a result, as shown in Table 1, the internal resistance of the stack was 100 mΩcm ² after the 50-cycle test, and no cracks or delamination was observed in the adhesive layer D even after the 100-cycle test. Durability was confirmed.

Example 5
8 (a) and 8 (b) are rear views showing the back surface shapes of the first and second metal plates 3 and 4 constituting the metal case 2 used in the fifth embodiment of the fuel cell power generation unit of the present invention. FIG.

The first metal plate 3 shown in FIG. 8 (a) is made of the same material as the metal plate 3 of the first embodiment shown above except that the notches 3m are provided at four locations on the outer frame portion 3b. Have the same structure (see FIG. 1).
On the other hand, the second metal plate 4 shown in FIG. 8B also has the same structure as the metal plate 4 used in Example 1 except that the outer frame portion 4b is provided with two notches 4m. And made of the same ferritic stainless steel (see FIG. 2).

Next, the same cell 5 as in the first embodiment is attached to the cell installation hole 3a of the first metal plate 3, and the gas is applied to both surfaces of the electric conductive plate 4e of the second metal plate 4 in the same manner as in the first embodiment. The transparent metal body 4g and the metal body 4h are spot-welded.
Then, by welding the two metal plates 3 and 4 at the outer frame portions 3b and 4b, the power generation unit 1 is formed as shown in FIG. 9A.

  Next, as in the first embodiment, the power generation unit 1 is stacked in five stages, and the outer frame portions 3b and 4b are bonded using silver-copper brazing (Ag-5% Cu), whereby the fuel cell stack 10 is formed. Is obtained (see FIG. 4).

In the obtained fuel cell stack 10, the outer frame portions 3b and 4b of each power generation unit 1 are provided with notches 3m and 4m, which are flexible units. From these notches 3m and 4m, fuel gas (hydrogen ) And oxidizing gas (air) will leak.
Therefore, as shown in FIG. 9 (b), a metal foil 8 having a thickness of 50 μm is pasted around the fuel cell stack 10 as a metal thin plate with a silver-copper brazing, thereby preventing gas leakage. .

  FIG. 9C is an overall view of the fuel cell stack 10 according to this embodiment. As shown in FIG. 4, the end plates 6 and 7 are originally arranged at the upper and lower positions of the fuel cell stack, but these are not shown in FIGS. 9 (b) and 9 (c). Yes.

The fuel cell stack 10 was subjected to the same durability test as that of each of the above examples. As shown in Table 1, the internal resistance of the stack was 80 mΩcm ² after the 50-cycle test. Further, even after 100 cycles of the test, no cracking or peeling was observed in the adhesive layer D, and it was confirmed that the same excellent durability as in Example 1 was exhibited.

[Comparative Example]
FIG. 10A is a cross-sectional view showing the structure of a conventional power generation unit used as a comparative example for the present invention. In the power generation unit 20 shown in the figure, the first metal plate 3 is basically the above-described structure. It has the same structure as each example, and the cell 5 is similarly attached to the cell installation hole 3a.
On the other hand, the second metal plate 40 has an integral structure, and the first embodiment is the same as the first embodiment except that the flat portion 40e functioning as a gas partition and a current collecting path is continuous from the outer frame portion serving as an adhesion portion at the time of lamination. The structure is basically the same as that of the metal plate 4 used. And the gas-permeable metal bodies 40g and 40h which function as a collector are spot-welded similarly to the upper and lower surfaces of the said plane part 40e.

  FIG. 10B shows the structure of a fuel cell stack in which the power generation units 20 are stacked in five stages, and is made of BCAS glass in a state where the end plates 6 and 7 are arranged at the upper and lower positions of these units. The outer frame portions of the units 20 are bonded to each other by the insulating adhesive layer I.

The fuel cell stack thus obtained was subjected to the same durability test as in the above examples. As shown in Table 1, the internal resistance of the stack was as high as 350 mΩcm ² after the 50-cycle test. It was found that the current collection performance was inferior. Moreover, the crack was recognized by the contact bonding layer I in the early stage of 20 cycles, and it was confirmed that it is inferior to durability.

It is the front view (a), back view (b), and longitudinal cross-sectional view (c) which show the structure of the 1st metal plate which comprises one side of the metal case used for the 1st Example of this invention. It is the front view (a), back view (b), and longitudinal cross-sectional view (c) which show the structure of the 2nd metal plate which comprises the other of the metal case used for the 1st Example of this invention. It is sectional drawing which shows the structure of the fuel cell power generation unit formed by the 1st Example of this invention. It is sectional drawing which shows the structure of the fuel cell stack formed by laminating | stacking the electric power generation unit shown in FIG. 3 in five steps. (A) It is sectional drawing which shows the structure of the fuel cell power generation unit formed by the 2nd Example of this invention. (B) It is a perspective view which shows the structure of the electrical-conduction board used for the electric power generation unit shown to Fig.5 (a). (A) It is sectional drawing which shows the structure of the fuel cell power generation unit formed by the 3rd Example of this invention. (B) It is a top view which shows the structure of the electrical-conduction board used for the electric power generation unit shown to Fig.6 (a). It is sectional drawing which shows the structure of the fuel cell stack formed by the 4th Example of this invention. (A) And (b) is a back view which shows the structure of the 1st and 2nd metal plate which comprises the metal case used for the 5th Example of this invention, respectively. (A) It is a perspective view which shows the structure of the fuel cell power generation unit formed by the 5th Example of this invention. (B) It is explanatory drawing of the point which affixes metal foil on the fuel cell stack formed by laminating | stacking five steps | paragraphs of the electric power generation units shown to Fig.9 (a). (C) It is a perspective view which shows the structure of the fuel cell stack formed by laminating | stacking 5 steps | paragraphs of the electric power generation unit shown to Fig.9 (a). (A) It is sectional drawing which shows the structure of the conventional type fuel cell power generation unit as a comparative example of this invention. (B) It is sectional drawing which shows the conventional type fuel cell stack structure which laminated | stacked the electric power generation unit shown to Fig.10 (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell power generation unit 2 Metal case 3 1st metal plate 3b Outer frame part 3c Air hole (oxidizing gas flow path)
3d Hydrogen hole (fuel gas flow path)
3m Notch 4 Second metal plate 4b Outer frame 4c Air hole (oxidizing gas flow path)
4d Hydrogen hole (fuel gas flow path)
4e Electric conductive plate 4g, 4h (gas permeable) metal body 4j Through-hole 4k Nickel (conductive material)
4m notch 8 metal foil (metal thin plate)
10 Fuel cell stack

Claims (10)

A first metal plate that supports the cell and a second metal plate that separates the fuel gas and the oxidizing gas, and the cell is included in a metal case having flow paths for the fuel gas and the oxidizing gas. A power generation unit comprising:
The second metal plate includes an electric conductive plate serving as an energization path in a central portion, and the electric conductive plate is electrically insulated from an outer frame portion provided with a manifold portion. .   2. The fuel cell power generation unit according to claim 1, wherein the electric conductive plate is made of metal and is bonded to an outer frame portion of the second metal plate via an electrically insulating adhesive layer.   2. The fuel cell power generation unit according to claim 1, wherein the electric conductive plate is made of metal, and is bonded to an outer frame portion of the second metal plate via a plate material having electrical insulation.   The electrical conductive plate is made of an electrically insulating material having a large number of through holes, is bonded to the outer frame portion of the second metal plate, and the through holes are filled with a conductive material. The fuel cell power generation unit according to claim 1.   The fuel cell power generation unit according to any one of claims 1 to 4, wherein a metal body having gas permeability is electrically connected to the electric conductive plate.   The fuel cell power generation unit according to any one of claims 1 to 5, wherein a cutout portion is provided in at least one outer frame portion of the first and / or second metal plate.   A plurality of the fuel cell power generation units according to any one of claims 1 to 6 are stacked, and the power generation units are bonded to each other via an adhesive layer having rigidity lower than that of the first and second metal plates. A fuel cell stack characterized by comprising:   A plurality of fuel cell power generation units according to claim 6 are stacked, the power generation units are bonded to each other via an adhesive layer having a rigidity lower than that of the first and second metal plates, and a notch is provided. A fuel cell stack, characterized in that a thin metal plate is bonded to an outer frame portion of at least one of the first and second metal plates via an adhesive layer having rigidity lower than that of the first and second metal plates. .   9. The fuel cell stack according to claim 7, wherein the first and second metal plates are made of ferritic stainless steel, and the metal cases of the power generation unit are bonded to each other with a silver brazing material.   The silver brazing material layer is formed on the front surface and / or the back surface of the outer frame portion of the metal case in the power generation unit, and heating and pressurization are performed in a state where a plurality of power generation units are stacked. A method for producing a fuel cell stack according to any one of the above items.

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