JP2003086229A - Stack structure of fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stack structure of a fuel cell wherein pressure parts are eliminated or the pressure parts can be downsized even in case the pressure parts are installed. SOLUTION: (1) This is the stack structure 23 of the fuel cell 10 wherein a cell laminated body is constituted by plurally laminating modules 19 composed of cells 29 of one layer or more and the cell laminated body is tightened in the cell laminating direction of the cell laminated body, and wherein this is adhered by an adhesive 30 between the modules 19. (2) The cells 29 have plural sub-cells 31 in the same plane. (3) A plate 34 is installed at the side face of the cell laminated body, and at least one part 30c of the adhesive 30 is filled between the plate 34 and the side face of the cell laminated body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell stack structure, and more particularly to a solid polymer electrolyte fuel cell stack structure.

[0002]

2. Description of the Related Art A unit cell of a solid polymer electrolyte fuel cell is a membrane-electrode assembly (MEA: Membrane-Electro
de Assembly) and a separator. Membrane-Electrode Assembly (MEA)
Is composed of an electrolyte membrane composed of an ion exchange membrane, an electrode (anode, fuel electrode) composed of a catalyst layer and a diffusion layer arranged on one surface of the electrolyte membrane, and a catalyst layer and a diffusion layer arranged on the other surface of the electrolyte membrane. It consists of electrodes (cathode, air electrode). The separator forms a fluid passage for supplying a fuel gas (anode gas, hydrogen) and an oxidizing gas (cathode gas, oxygen, usually air) to the anode and the cathode. The fuel cell stack is a module in which one or more layers of cells are stacked, a plurality of modules are stacked to form a cell stack, and terminals, insulators, and end plates are arranged at both ends of the cell stack in the cell stacking direction. The cell stack is fastened in the cell stacking direction and is fixed outside the cell stacking body by a fastening member (for example, a tension plate) extending in the cell stacking direction. In the solid polymer electrolyte fuel cell, hydrogen is converted into hydrogen ions and electrons on the anode side, the hydrogen ions move to the cathode side in the electrolyte membrane, and oxygen, hydrogen ions and electrons (on the anode of the adjacent MEA) move on the cathode side. The electrons generated in (1) come through the separator, and the electrons of the cell at one end of the cell stack come to the cell at the other end of the cell stack through the external circuit) to generate water. Anode side: H ₂ → 2H ⁺ + 2e ⁻ Cathode side: 2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O Joule heat and heat generated in the water generation reaction at the cathode are cooled between the separators. In each of the cells, a flow path through which a cooling medium (usually, cooling water) flows is formed for each cell or for each of a plurality of cells to cool the fuel cell. In order for the above electrochemical reaction to be performed normally, electrical contact between the separator and the electrode is maintained, and fluid such as fuel gas, oxidizing gas, and refrigerant leaks between the separator and the electrode or between the separators. In order not to do so, the cell stack (which is also a module stack) must be clamped in the cell stacking direction and the clamp must be retained. The conventional tightening and holding of the cell stack is disclosed in, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Application Publication No. It is being appreciated.

[0003]

However, the conventional method of clamping and holding the cell stack body requires a pressurizing component including a spring, and in order to obtain the necessary electrical contact and seal, the pressurizing component is pressed. The parts are large and heavy. Also,
In order to reduce the length of the cell stack in the cell stacking direction, a plurality of (for example, n) subcells are arranged in the same plane of the cell and are connected in the stacking direction to form a substack in series or in parallel. When attempting to connect, the cell area becomes multiple (for example, n) times, and in proportion thereto, the pressurizing component becomes large and heavy, and the shortening of the cell stack is offset by the increase in the pressurizing component. As a result, the effect of shortening the length of the cell stack cannot be obtained as expected. An object of the present invention is to provide a stack structure of a fuel cell in which the pressurizing component can be eliminated or the pressurizing component can be downsized even if the pressurizing component is provided.

[0004]

The present invention which achieves the above object is as follows. (1) A stack structure of a fuel cell, wherein a plurality of modules each including one or more cells are stacked to form a cell stack, and the cell stack is fastened in the cell stacking direction.
A fuel cell stack structure in which modules are glued together. (2) The fuel cell stack structure according to (1), wherein the cells have a plurality of sub-cells in the same plane. (3) The fuel cell stack structure according to (1), wherein a plate is provided on a side surface of the cell stack, and at least a part of the adhesive is filled between the plate and the side surface of the cell stack.

In the fuel cell stack structure of the above (1), since the modules are adhered to each other with an adhesive, the pressing force can be held by the adhesive, and the pressurizing component which has been conventionally required is not necessary or provided. Can be downsized, and as a result, the fuel cell stack can be downsized (shortened in the cell stacking direction), and the weight and cost can be reduced. In the fuel cell stack structure of the above (2), even if a cell has a plurality of sub-cells in the same plane, the cell area increases, but there is no pressurizing part or the size can be reduced, so that the pressurizing part becomes large. It is possible to maintain the advantage of shortening the stack by providing a plurality of subcells in the same plane without incurring. In the fuel cell stack structure of (3) above, since the plate is provided on the side surface of the cell stack and at least a part of the adhesive is filled between the plate and the side surface of the cell stack, the pressure is applied to the adhesive. It can be held by a plate, eliminating the need for pressurizing parts that were required in the past, or even providing them can be downsized,
As a result, the fuel cell stack can be downsized (shortened in the cell stacking direction), and the weight and cost can be reduced. In addition, the plate can protect the cell stack even when the vehicle collides.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a stack structure of a fuel cell of the present invention will be described with reference to FIGS. 1 to 8 (FIGS.
This will be described with reference to FIG. 8 (comparative example). The fuel cell 10 to which the stack structure of the present invention is applied is a solid polymer electrolyte fuel cell. The fuel cell 10 of the present invention is mounted in, for example, a fuel cell vehicle. However, it may be used for other than automobiles.

The unit cell 29 of the solid polymer electrolyte fuel cell 10 comprises a membrane-electrode assembly (MEA: Membrane-Electrode Assembly) and a separator 18, as shown in FIGS. The MEA is arranged on the electrolyte membrane 11 made of an ion exchange membrane, the electrode 14 (anode, fuel electrode) made of the catalyst layer 12 and the diffusion layer 13 arranged on one surface of the electrolyte membrane 11, and the other surface of the electrolyte membrane 11. And an electrode 17 (cathode, air electrode) including the catalyst layer 15 and the diffusion layer 16 thus formed.

The separator 18 includes a fluid passage 27 for supplying fuel gas (hydrogen) to the anode 14 and the electrode 1.
A fluid passage 28 for supplying an oxidizing gas (oxygen, usually air) and a coolant passage 26 through which a coolant (cooling water) for cooling the fuel cell flows are formed. The coolant channel 26 is provided for each cell or for each of a plurality of cells. For example, 2
One refrigerant flow path 26 is provided for each cell. The separator 18 includes a fuel gas and an oxidizing gas, a fuel gas and a cooling water,
Either the oxidizing gas or the cooling water is separated from each other, and an electric passage for electrons to flow from the anode to the cathode of the adjacent cell is formed. The separator 18 is formed by forming a refrigerant flow path 26 and gas flow paths 27, 28 on a carbon plate, or by stacking a plurality of uneven metal plates forming the flow paths 26, 27, 28, or It is made of any one of a conductive resin plate (for example, a resin plate mixed with conductive material particles to have conductivity) and formed with the coolant flow paths 26 and the gas flow paths 27 and 28. The example shown is separator 1
The case where 8 is made of a carbon plate is shown.

The stack 23 of the fuel cell has a module 19 composed of cells 29 of one or more layers (two layers in FIG. 2) (when one module is composed of a plurality of cells, a separator 18 sandwiching the electrolyte membrane 11 between the cells). (Which are fixed by the adhesive 30b in between) to form a cell stack, the cell stack is fastened in the cell stacking direction, and the modules 19 are bonded by the adhesive 30a. The adhesive 30b between the cells holds the electrodes between the separators and requires insulation. Adhesive 30a between modules
Although it is possible to use a conductive material that seals between the modules, an insulating material may be used because it is difficult to separate it from an insulating material. The adhesive 30 is
It may be formed by coating on the side surface of the cell stack. The adhesive 30c applied and formed on the side surface of the cell stack has an insulating property in order to ensure the insulating property between the cells. Tightening of the cell stack in the cell stacking direction is necessary for obtaining electrical contact between the separator and the electrode and for sealing the fuel gas, the oxidizing gas, and the refrigerant. At both ends of the cell stack in the cell stacking direction, a terminal 20, an insulator 21, and if necessary, end plates 22 are arranged.

The adhesive material 30 (30a, 30b) is composed of a resin as a main component and a material which is dried and solidified. Adhesive 30
May include a ceramic bead (ceramic globule) when it is used in a portion where it is necessary to prevent contact between the separators or between the separator and the metal plate when tightening the cell stack. The adhesive 30b is applied to the module facing surface when the cells are stacked to form a cell stack, and the adhesive 30c is applied to the side surface of the cell stack after the cells are stacked. After that, the adhesives 30b and 30c are dried,
It is solidified and becomes a cell tightening load holding member. As shown in FIG. 2, the fastening load between the cells 29 in the cell stacking direction and between the modules 19 is maintained by the adhesive 30 (30a, 3a).
0b, 30c). In addition, as shown in FIG. 4, a plate 34 may be provided outside the cell stack if necessary.
Is placed, the space between the side surface of the plate 34 and the cell stack is filled with the adhesive 30 (30c), and dried and solidified to form the plate 3
4 and the adhesive 30 (30a, 30b, 30c) may hold the tightening load between the modules. When the plate 34 is provided, both ends of the plate 34 are attached to the end plates 22 by bolts 25 extending in a direction orthogonal to the cell stacking direction.
You may fix with.

As shown in FIG. 3, the cell 29 has a plurality of sub-cells 31 (the number of which is not limited to 4 in the figure, but is limited to 4) electrically insulated from each other in the same plane. You may have. In the same plane, the subcell 31 shares the electrolyte membrane 11, but the electrodes 14 and 17 are electrically isolated from each other independently of each other. When the cells 29 are stacked, the sub cells 31 are connected in series in the cell stacking direction to form a sub stack. The sub-stacks are electrically connected in series or in parallel with each other at the cell stacking direction ends of the cell stack. Cell 29 has multiple subcells 3
By having 1, the length of the cell stack in the cell stacking direction is shortened.

5 to 8 show comparative examples (not included in the present invention). 5 and 6, cells having the same cell area as the subcell 31 of the present invention are stacked, a pressure plate 32 is arranged at one end of the cell stack in the cell stacking direction, and a plate is provided between the pressure plate 32 and the end plate 22. An example in which the spring 33 is arranged and a fastening load is applied to the cell stack is shown.

7 and 8 are also comparative examples, but four subcells (each subcell area is shown in FIG. 6) in the same plane.
Cells having the same cell area) are stacked to make the cell stack length ¼ of that of FIG. Since the cell area is four times that in FIG. 6, the load applied in the cell stacking direction is four times that in FIGS. 5 and 6. Therefore, the pressure plate 32 and the end plate 2
2. The disc spring 33 becomes large both in the cell stacking direction and in the direction orthogonal thereto. As a result, even if the cell stack length is ¼ of that of FIG. 5, the stack length including the cell stack and the pressurizing component is increased by increasing the pressurizing component.
It does not become 1/4 of that of the above, but becomes larger than that, and the effect of shortening the cell stack due to the formation of subcells is diminished.

Next, the operation of the fuel cell stack structure of the present invention will be described. In the stack structure of the fuel cell of the present invention, the modules 19 are adhered to each other by the adhesive, so that the pressing force can be held by the adhesive, and the pressurizing components (the disc spring 33 and the pressure shown in FIGS. Plate 32
1) becomes unnecessary as shown in FIG. 1, or even if a pressing component such as a disc spring is provided, the size can be reduced in the cell stacking direction. As a result, the fuel cell stack can be downsized (shortened in the cell stacking direction), and the weight and cost can be reduced.

Even if the cell 29 has a plurality of sub-cells 31 in the same plane as in the stack structure of the fuel cell shown in FIG. 3, the area of the cell 29 is increased, but there is no pressurizing component or the size is reduced. Therefore, it is possible to maintain the advantage of shortening the stack length by providing a plurality of sub-cells in the same plane without increasing the size of the pressurizing component. More specifically, in the fuel cell stack structure of FIG. 3 of the present invention, when the area of each subcell 31 is equal to that of FIG. 6, the cell stacking direction of the cell stack of the cell 29 having the subcell 31 of FIG. Is 1 / the number of subcells of the cell stacking direction length of the cell stack of FIG. In the example of FIG. 3, since the number of subcells is 4, the length of the cell stack in which the cells 29 of FIG. 3 are stacked is 1/4 of the length of the normal cell stack of FIG. In the present invention, the adhesive 30
Since the tightening load in the cell stacking direction is maintained at,
As described above, it is not necessary to provide a disc spring at one end of the cell laminated body, or even if it is provided, it is downsized in the cell laminating direction as compared with the pressing component including the disc spring 33 and the pressure plate 32 of FIG.

In the stack structure of the fuel cell shown in FIG. 4, the plate 34 is provided on the side surface of the cell stack, and the adhesive 3
Since at least a part 30c of 0 is filled between the plate 34 and the side surface of the cell stack, the pressing force can be held by the adhesive 30c and the plate 34, and the pressurizing component which is conventionally required is unnecessary. Even if provided, it can be miniaturized. As a result, the fuel cell stack can be downsized (shortened in the cell stacking direction), and the weight and cost can be reduced.
Further, the plate 34 is a structural material similar to the tension plate 24 (FIGS. 5 and 7) that extends between both end plates and holds a stack fastening load, but the plate 34 of the present invention is Since the stack tightening load is received by both the adhesive agent 30, the thickness of the plate 34 can be made smaller than the thickness of the tension plate 24 as compared with the conventional case in which the tightening force is received only by the tension plate 24. Therefore, even when the plate 34 is provided, the weight is reduced compared to the conventional case where the tension plate 24 is provided. Also, the plate 34
Is disposed on the front side of the stack 23 in the vehicle front-rear direction when the vehicle is mounted on the vehicle, the plate 34 can protect the cell stack even when the vehicle collides. Therefore, the plate 34 plays a role of receiving the fastening force and also has a stack protection effect at the time of a vehicle collision.

[0017]

According to the fuel cell stack structure of the first aspect of the present invention, since the modules are adhered to each other by the adhesive, the pressing force can be held by the adhesive, and the pressurizing component which has been conventionally required is unnecessary. , The fuel cell stack can be downsized, and as a result, the fuel cell stack can be downsized (shortened in the cell stacking direction), and the weight and cost can be reduced. According to the stack structure of the fuel cell of claim 2, even if the cell has a plurality of sub-cells in the same plane, the cell area is increased, but since there is no pressurizing part or the size can be reduced, a large pressurizing part can be used. It is possible to maintain the advantage of shortening the stack by providing a plurality of subcells in the same plane without increasing the cost. According to the fuel cell stack structure of claim 3,
Since the plate is provided on the side surface of the cell stack and at least a part of the adhesive is filled between the plate and the side surface of the cell stack, the pressing force can be held by the adhesive and the plate, which is conventionally required. It is possible to reduce the size of the fuel cell stack (shorten in the cell stacking direction) as well as to reduce the weight and cost, as a result of eliminating the need for components or reducing the size even if they are provided. In addition, the plate can protect the cell stack even when the vehicle collides.

[Brief description of drawings]

FIG. 1 is a side view of a fuel cell to which a fuel cell stack structure of the present invention is applied.

2 is an enlarged cross-sectional view of a portion of the fuel cell of FIG.

FIG. 3 is a front view of a cell having a plurality of sub-cells in the same plane in the fuel cell stack structure of the present invention.

FIG. 4 is an enlarged cross-sectional view of a part of the fuel cell in the fuel cell stack structure of the present invention in which a plate is provided on the side surface of the cell stack and resin is filled between the plate and the side surface of the cell stack. .

FIG. 5: Comparative example 1 (cell does not have a plurality of subcells)
3 is a side view of the fuel cell of FIG.

6 is a front view of a cell of the fuel cell of FIG.

FIG. 7 is a side view of a fuel cell of Comparative Example 2 (cell has a plurality of subcells).

FIG. 8 is a front view of a cell of the fuel cell of FIG.

[Explanation of symbols]

10 (Polymer electrolyte type) fuel cell 11 Electrolyte membrane 12 Catalyst layer 13 Diffusion layer 14 electrodes (anode, fuel electrode) 15 Catalyst layer 16 diffusion layer 17 electrodes (cathode, air electrode) 18 separator 19 modules 20 terminals 21 insulator 22 End plate 23 stack 24 tension plate 25 volts 26 Refrigerant flow path 27 Fuel gas flow path 28 Oxidizing gas flow path 29 cells 30 adhesive 30a module adhesive 30b Cell adhesive 30c Adhesive between plate and side surface of cell stack 31 subcell 32 Pressure plate 33 Disc spring 34 plates

Claims (3)

[Claims] 1. A fuel cell stack structure in which a plurality of modules each including one or more layers of cells are stacked to form a cell stack, and the cell stack is fastened in the cell stacking direction. Fuel cell stack structure bonded with chemicals. 2. The fuel cell stack structure according to claim 1, wherein the cells have a plurality of sub-cells in the same plane. 3. The fuel cell stack structure according to claim 1, wherein a plate is provided on a side surface of the cell stack, and at least a part of the adhesive is filled between the plate and a side surface of the cell stack.