JP5109277B2 - Multi-cell module and fuel cell stack - Google Patents

Description

  The present invention relates to a module (multi-cell module) in which a plurality of cells are stacked, and a fuel cell stack including the stacked multi-cell modules.

As disclosed in Japanese Patent Application Laid-Open No. 2004-207074, a fuel cell (cell) includes an MEA (membrane-electrode assembly) sandwiched between separators. A gas diffusion layer is interposed between the MEA and the separator. The cells are stacked to form a fuel cell stack.
Since separators are thin plates and flow paths are formed, especially metal separators are low in rigidity. In many cases, a bulging deformation is generated. When the deformed cells are stacked to form a stack, warpage and deformation are accumulated. As a result, when the stack fastening load is applied, the surface pressure applied to the cell becomes non-uniform, the contact resistance increases at the portion where the surface pressure is small, the output performance decreases, and it becomes difficult to ensure the sealing performance, etc. Problems arise.
In order to suppress the warpage and deformation of the separator and the cell, as disclosed in JP 2002-151136 A, a metal or carbon correction plate may be interposed for each predetermined number of cells. (For example, JP 2002-151136 A).
Japanese Patent Laid-Open No. 2004-207074 JP 2002-151136 A

However, it is difficult to solve the problem of uneven surface pressure between the central portion and the outer portion of the cell only by interposing a metal or carbon correction plate for each predetermined number of cells.
Therefore, a metal or carbon correction plate is interposed for each predetermined number of cells, a clamping load is applied in the cell stacking direction, and the correction plates are constrained by an outer frame to be modularized (unitized). The problem of uneven surface pressure between the central part and the outer part is suppressed, but on the other hand, when the correction plates at both ends of the module are subjected to loads away from each other due to the surface pressure from the diffusion layer in the central part of the cell. There arises a problem that a high stress is applied to a joint portion (for example, a bonding portion) between the correction plate and the outer frame, and the durability is affected (peeling in the case of bonding).

A first object of the present invention includes a multi-cell module capable of solving the problem of non-uniform surface pressure between a cell central portion and an outer portion in a cell laminate in which a plurality of cells are laminated and a fastening load is applied, and the multi-cell module. It is to provide a fuel cell stack.
A second object of the present invention is to provide a multi-cell module that can achieve the first object without damaging the connecting portion between the plates at both ends of the multi-cell module and the outer frame that connects the plates, and a fuel cell stack including the multi-cell module. Is to provide.

The present invention for solving the above problems and achieving the above object is as follows.
(1) (a) A multi-cell module in which a plurality of layers are stacked to form a module stack of a fuel cell stack,
(B) The multi-cell module is
A cell stack including a plurality of stacked cells; and
A first clamping member that sandwiches the outer side of the stacking end face of the cell stack in the cell stacking direction;
A second sandwiching member that is movable in the cell stacking direction with respect to the first sandwiching member, sandwiching the inner side of the stack end face of the cell stack in the cell stacking direction;
Including
(C) The first sandwiching member is a rigid body, one on each surface of the cell stack in the cell stacking direction, and a pair of both surfaces, and the pair of first sandwiching members are connected to each other via a connecting side plate. The second sandwiching member is a rigid body, one on each side of the cell stacking direction of the cell stack, and a pair on both sides.
(D) In the free state of the multi-cell module, the distance D2 between the pair of second clamping members is larger than the distance D1 between the pair of first clamping members, and when the stack fastening load is applied to the multi-cell module, The multi-cell module, wherein a distance between the pair of second clamping members is smaller than a distance D2 between the pair of second clamping members in a free state of the multi-cell module.
(2) multi-cell module of the cell containing the metal separator (1) Symbol placement.
(3) (1) or (2) Symbol mounting the multi-cell module, a plurality, laminated, a fuel cell stack granted stack fastening load of.
( 4 ) The fuel cell stack according to ( 3 ) , wherein one or more plate-shaped members made of the first and second clamping members having a bending rigidity in the cell stacking direction larger than those of the cells are interposed between the cells. .
( 5 ) The fuel cell stack according to ( 4 ), wherein the cell that contacts one surface of the plate member and the cell that contacts the other surface bend in opposite directions, and the plate member does not bend.

According to the multi- cell module of (1) above, a plurality of multi-cell modules are stacked to form a module stack of a fuel cell stack. Therefore, each multi-cell module can absorb cell deformation and accumulate cell deformation over the entire stack. Can be prevented.
Further, the second holding member is movable in the cell stacking direction with respect to the first holding member, and in the free state of the multi-cell module, the distance D2 between the pair of second holding members is the distance between the pair of first holding members. Since the distance is larger than the distance D1 , when the second clamping members at both ends of the multi-cell module receive a surface pressure from the diffusion layer, they move away from each other and can absorb the drum-like deformation of the cell stack .
Further, when the stack fastening load is applied to the multi-cell module, the distance between the pair of second clamping members is smaller than the distance D2 between the pair of second clamping members in the free state of the multi-cell module. the second clamping member at both ends of the moving toward each other, becomes substantially the same position as the first clamping member, can solve the surface圧不uniformity problems with cell central portion and the outer portion.

Further , according to the multi-cell module of ( 1 ), since the second clamping member is movable in the cell stacking direction with respect to the first clamping member, the second clamping members at both ends of the multi-cell module are separated from the diffusion layer. Can be moved away from each other when the surface pressure is received. As a result, when modularized, a large load is not applied from the second clamping member to the first clamping member, and the connecting portion between the first clamping member and the connecting side plate is not damaged.
According to the multi-cell module of ( 2 ) above, since the cell includes a metal separator and the metal separator has low rigidity, the cell stack is easily deformed into a drum shape when subjected to surface pressure from the diffusion layer. The problem solving according to the above (1) according to the invention is particularly effective.

According to the fuel cell stack of ( 3 ) above, a plurality of the multi-cell modules of (1) or ( 2 ) are stacked and a stack fastening load is applied to form a stack, so that deformation accumulates over all cells of the stack. Each multi-cell module can absorb the drum-like deformation of the cell stack, can solve the problem of non-uniform surface pressure between the cell central portion and the outer portion, and each multi-cell module can solve the first problem at both ends of the multi-cell module. It is possible to prevent damage to the connecting portion between the holding member and the outer frame connecting the holding member.
According to the fuel cell stack of ( 4 ) above, since one or more plate-like members (first and second clamping members) having a bending rigidity in the cell stacking direction larger than that of the cells are interposed between the cells, Flatness and perpendicularity (perpendicularity with respect to the cell stacking direction of both end faces of the multicell module) are output at both ends of each multicell module in the cell stacking direction.
According to the description of the fuel cell stack of ( 5 ) above, the cell that contacts one surface of the plate member and the cell that contacts the other surface bend in opposite directions, and the plate member does not bend .

Hereinafter, a multi-cell module of the present invention and a fuel cell stack in which the multi-cell module is laminated will be described with reference to FIGS.
First, the fuel cell (cell) included in the multi-cell module of the present invention and the fuel cell stack in which the multi-cell module is laminated is a low-temperature fuel cell, for example, a solid polymer electrolyte fuel cell 10. The fuel cell 10 is mounted on, for example, a fuel cell vehicle. However, it may be used other than an automobile.
As shown in FIG. 4, the solid polymer electrolyte fuel cell 10 includes a laminate of a membrane-electrode assembly (MEA) 19 and a separator 18.
The membrane-electrode assembly 19 includes an electrolyte membrane 11 made of an ion exchange membrane, an electrode (anode, fuel electrode) 14 made of a catalyst layer arranged on one surface of the electrolyte membrane 11, and a catalyst arranged on the other surface of the electrolyte membrane 11. It consists of electrodes (cathode, air electrode) 17 composed of layers. Between the membrane-electrode assembly 19 and the separator 18, gas diffusion layers (also simply referred to as diffusion layers) 13 and 16 are provided on the anode side and the cathode side, respectively.
As shown in FIG. 1, a cell 10 is configured by stacking a membrane-electrode assembly 19 and a separator 18, and a plurality of cells 10 are stacked to form a cell stack 1. A multi-cell module (a module that is a unit of handling by a plurality of cells) 3 is configured by arranging a clamping member 2 that sandwiches the two.

As shown in FIG. 3, a plurality of multi-cell modules 3 are stacked in the cell stacking direction to form a module stack, and terminals 20, insulators 21 and end plates 22 are arranged at both ends of the module stack in the cell stacking direction. The plate 22 is fixed with fastening members 24 (for example, through bolts) and nuts 25 extending in the cell stacking direction, and the module stack is tightened in the cell stacking direction to apply a stack fastening load to form the fuel cell stack 23. The stack fastening load is applied by, for example, arranging a pressure plate 37 inside the end plate 22 on one end side of the stack, and arranging a spring 35 (for example, a disc spring) between the end plate 22 and the pressure plate 37 by a spring force. This can be done by applying a stack fastening force (other methods are also possible).

  As shown in FIGS. 4 and 5, the separator 18 is formed with a fuel gas flow path 27 for supplying fuel gas (hydrogen) to the anode 14 in the power generation region 51, and an oxidant gas (oxygen, oxygen) is supplied to the cathode 17. An oxidizing gas passage 28 for supplying air (usually air) is formed. The separator 18 is also formed with a refrigerant flow path 26 for flowing a refrigerant (usually cooling water). In the separator 18, a fuel gas manifold 30, an oxidizing gas manifold 31, and a refrigerant manifold 29 are formed in the non-power generation region 52. The fuel gas manifold 30 is in communication with the fuel gas passage 27, the oxidizing gas manifold 31 is in communication with the oxidizing gas passage 28, and the refrigerant manifold 29 is in communication with the refrigerant passage 26.

An ionization reaction that converts hydrogen into hydrogen ions (protons) and electrons is performed on the anode 14 side of each cell 19, and the hydrogen ions move through the electrolyte membrane 11 to the cathode 17 side. Water is generated from ions and electrons (electrons generated at the anode of the adjacent MEA come through the separator, or electrons generated at the anode of the cell at one end in the cell stacking direction come to the cathode of the other end cell through an external circuit), Power generation is performed according to the following formula.
Anode side: H ₂ → 2H ⁺ + 2e ⁻
Cathode side: 2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O

  The separator 18 is made of a metal separator (including a combination with a resin frame) or a carbon separator. FIG. 4 shows a case where the separator 18 is a metal separator.

  As shown in FIGS. 5 and 1, various fluids are sealed from each other and from the outside. Between the two separators 18 sandwiching the MEA 19 of each cell 10 is sealed by a first seal member 32, and between adjacent cells 19 is sealed by a second seal member 32, and between the multi-cell modules. Is sealed by a third seal member 32. Between the metal separator 18 and the electrolyte membrane 11, a resin frame (a frame made of resin in which the power generation region 51 is hollowed out and having a manifold hole) is interposed in the non-power generation region 52. In some cases, the first seal member 32 seals between the metal separator 18 and the resin frame and between the resin frame and the electrolyte membrane 11.

  The 1st seal member 32, the 2nd seal member 32, and the 3rd seal member 32 are constituted from gaskets, such as adhesives and rubber, for example. The 1st seal member 32, the 2nd seal member 32, and the 3rd seal member 32 may be constituted from the same seal member, and may be constituted from mutually different seal members.

As shown in FIGS. 1 and 2, the multi-cell module 3 includes a cell stack 1 including a plurality of stacked cells 10 and a sandwiching member 2 that sandwiches the cell stack 1 in the cell stacking direction.
The sandwiching member 2 includes a first sandwiching member 4 that sandwiches the outer portion (for example, the non-power generation region 52) of the stack end surface of the cell stack 1 in the cell stack direction, and the inner side of the stack end surface of the cell stack 1. A second clamping member 5 that is movable in the cell stacking direction with respect to the first clamping member 4 that sandwiches the portion (for example, the power generation region 51) in the cell stacking direction. The second clamping member 5 is inside the first clamping member 4. The movable structure of the second clamping member 5 relative to the first clamping member 4 is, for example, provided with a pin 7 on one of the second clamping member 5 and the first clamping member 4 and a groove 8 on the other, This can be achieved by allowing 7 to slide in the groove 8. However, other movable structures may be used.

The 1st clamping member 4 is a rigid body, and there exist a pair in the cell lamination direction both-surface part of the cell laminated body 1 (one piece on each surface, a pair on both surfaces). The pair of first clamping members 4 are connected to each other via a connection side plate 6 (may be called an outer frame plate) provided along the outer peripheral surface of the cell stack 1. However, it cannot move in the cell stacking direction. 1 and 2, the first clamping member 4 and the connecting side plate 6 are connected and fixed by, for example, screws 9. The first clamping member 4 also has a hole 36 through which the connecting bolt 24 of the stack is inserted.
The 2nd clamping member 5 is a rigid body, and there exists a pair in the cell lamination direction double-sided part of the cell laminated body 1 (one piece on each surface, a pair on both surfaces). The 2nd clamping member 5 is electroconductive, for example, is metal. The first clamping member 4 may be conductive (for example, made of metal) or insulative (for example, made of resin).
The connecting side plate 6 is insulative and is made of resin, for example. The first clamping member 4 and the second clamping member 5 have a sufficiently large bending rigidity as compared with the cell 10.

The multi-cell module 3 has a plurality of clamping members 4 and 5 in the cell in-plane direction. The plurality of sandwiching members 4 and 5 sandwich the cell stack 1 in the cell stacking direction at intervals D1 and D2 that are different from each other when the stack fastening load is not applied to the multicell module 3.
The sandwiching member 2 (including the first sandwiching member 4 and the second sandwiching member 5) is in a free state in which no stack fastening load is applied to the multicell module 3, and is closer to the outer peripheral end of the cell than the center of the cell. The cell stack 1 is sandwiched in the cell stacking direction at short intervals.
Of the clamping members 2, the first clamping member 4 is not movable in the cell stacking direction, and the second clamping member 5 is movable in the cell stacking direction. The 2nd clamping member 5 is connected with the 1st clamping member 4 so that a movement is possible.

A plurality of multi-cell modules 3 are stacked in the cell stacking direction, and a stack fastening load is applied by a spring 35 to constitute a fuel cell stack 23.
In the fuel cell stack 23, one or more plate-like members 4 and 5 having a bending rigidity in the cell stacking direction larger than that of the cell 10 are arranged between the cells of one multi-cell module 3 between adjacent multi-cell modules 3. It is interposed between the cells of the adjacent multi-cell module 3.
In the fuel cell stack 23, the cells that contact one surface of the plate-like members 4 and 5 and the cells that contact the other surface bend in opposite directions, and the plate-like members 4 and 5 do not bend.
In the fuel cell stack 23, the cell includes a metal separator.

Next, functions and effects of the present invention will be described.
In the multi-cell module 3 of the present invention, since the second clamping member 5 can move in the cell stacking direction with respect to the first clamping member 4, the second clamping members 5 at both ends of the multi-cell module 3 are provided with the diffusion layer 13. , 16 can be moved away from each other when the surface pressure is received, and the drum-like deformation of the cell stack 1 can be absorbed. Further, since the first and second clamping members 4 and 5 constitute both end faces of the multi-cell module 3, the flatness and the perpendicularity between the cell stacking directions are obtained irrespective of the drum-like deformation of the cell 10. . Moreover, since the flatness of both end faces and the perpendicularity of the cell stacking direction are obtained in each multi-cell module 3, the deformation of the cell 10 does not accumulate even when stacked. In the case of stacking, a stack fastening load is applied, so that the second clamping members 5 at both ends of each multi-cell module 3 move in a direction in which they are close to each other, and almost the same as the first clamping member 4 in the cell stacking direction. The cell 10 is compressed by the first clamping member 4 and the second clamping member 5 over the entire area by the same amount (substantially uniformly), so that the surface pressure between the central portion and the outer portion of the cell 10 is not reduced. Uniform problem is solved.

  Since the second sandwiching member 5 is movable in the cell stacking direction with respect to the first sandwiching member 4, the second sandwiching members 5 at both ends of the multi-cell module 3 are the reaction force for compressing the diffusion layers 13 and 16. When subjected to surface pressure, they can move away from each other. As a result, when modularized, a large load is not applied from the second sandwiching member 5 to the first sandwiching member 1 in the cell stacking direction, and the connecting portion between the first sandwiching member 4 and the connecting side plate 6 is damaged. (Damage of the screw 9 or peeling of the bonded part when the first holding member 4 and the connecting side plate 6 are bonded with an adhesive instead of the screw 9) is prevented.

  The plurality of sandwiching members 4 and 5 are provided in the cell in-plane direction, and the plurality of sandwiching members 4 and 5 sandwich the cell stack in the cell stacking direction at different intervals D1 and D in the free state. The center clamping member 5 at both ends of the cell moves in a direction away from each other in the cell stacking direction, so that the drum-like deformation of the cell stack can be absorbed. When a plurality of multi-cell modules 3 are stacked to form a stack by applying a stack fastening load, the center clamping members 5 at both ends of each multi-cell module 3 move in the direction adjacent to each other in the cell stacking direction, and the outer circumferential clamping members 4 and approximately in the same direction in the cell stacking direction, it is possible to solve the problem of non-uniform surface pressure between the cell central portion and the outer portion when cells are simply stacked.

The sandwiching members 4 and 5 (in the free state of the multi-cell module 3) sandwich the cell stack in the cell stacking direction at a shorter distance from the center of the cell toward the end of the cell. A large load is not applied to the member, and even if the outer peripheral holding member is connected by the connecting side plate, the connecting portion between the outer peripheral holding member and the connecting side plate is not damaged.
The sandwiching members 4 and 5 are connected to the first sandwiching member 4 that is made immovable in the cell stacking direction by being connected by the connecting side plate 6 and the first sandwiching member 4 that is movable in the cell stacking direction. And the second holding member 5 at the both ends of the multi-cell module 3 can move away from each other when receiving the surface pressure from the diffusion layers 13 and 16. As a result, when modularized, a large load is not applied from the second sandwiching member 5 to the first sandwiching member 4 in the cell stacking direction, and the connecting portion (screw) of the first sandwiching member 4 and the connecting side plate 6 No damage is caused to the connection by 8 or the adhesive part by the adhesive.

  When the separator 18 of the cell 10 is a metal separator, since the metal separator has low rigidity, the cell stack is easily deformed into a drum shape when subjected to surface pressure from the diffusion layers 13 and 16. The drum-shaped deformation absorbing effect of the laminate 1 is particularly exerted.

  In the fuel cell stack 23, a plurality of the above-described multi-cell modules 3 are stacked to form a stack, so that the problem that deformation is accumulated over all the cells of the stack 23 as in the prior art is solved. The drum-like deformation of the laminate 1 can be absorbed. As a result, it is possible to solve the problem of uneven surface pressure between the cell central portion and the outer portion, and in each multicell module 3, the connecting portion between the first clamping member 4 at both ends of the multicell module and the outer frame 6 that connects it. Can prevent damage.

In the fuel cell stack 23, since one or more plate-like members 4 and 5 (first and second clamping members 4 and 5) having a bending rigidity in the cell stacking direction larger than the cells are interposed between the cells, Flatness and perpendicularity to the cell stacking direction are obtained at both ends of each multi-cell module 3.
In this case, the cell that contacts one surface of the plate-like members 4 and 5 and the cell that contacts the other surface bend in opposite directions, and the plate-like members 4 and 5 do not bend because they are rigid.
When the cell 10 includes a metal separator, since the metal separator has low rigidity, the cell stack 1 is easily deformed into a drum shape when subjected to surface pressure from the diffusion layers 13 and 16. No. 1 drum-shaped deformation absorbing effect is particularly exerted.

It is sectional drawing of the multicell module of this invention. It is a top view (or front view) of the multicell module of this invention. It is a side view of the fuel cell stack of the present invention. It is a cross-sectional view of a part of the multi-cell module and fuel cell stack of the present invention. It is the top view (or front view) of the multicell module seen from between the cells of the multicell module and the fuel cell stack of the present invention.

DESCRIPTION OF SYMBOLS 1 Cell laminated body 2 of a multicell module 2 Holding member 3 Multicell module 4 1st clamping member 5 2nd clamping member 6 Side plate for connection (outer frame board)
7 Pin 8 Groove 9 Screw 10 (Solid polymer electrolyte type) Fuel cell 11 Electrolyte membrane 13, 16 Diffusion layer 14 Anode 17 Cathode 18 Separator 19 MEA
20 Terminal 21 Insulator 22 End plate 23 Fuel cell stack 24 Fastening member (for example, through bolt)
25 Nut 26 Refrigerant flow path (cooling water flow path)
27 Fuel gas channel 28 Oxidizing gas channel 29 Refrigerant manifold 30 Fuel gas manifold 31 Oxidizing gas manifold 32 First, second and third seal members 35 Spring 36 Hole 37 Pressure plate 51 Power generation region 52 Non-power generation region

Claims (5)

(A) a multi-cell module in which a plurality of stacked modules constitute a fuel cell stack module stack,
(B) The multi-cell module is
A cell stack including a plurality of stacked cells; and
A first clamping member that sandwiches the outer side of the stacking end face of the cell stack in the cell stacking direction;
A second sandwiching member that is movable in the cell stacking direction with respect to the first sandwiching member, sandwiching the inner side of the stack end face of the cell stack in the cell stacking direction;
Including
(C) The first sandwiching member is a rigid body, one on each surface of the cell stack in the cell stacking direction, and a pair of both surfaces, and the pair of first sandwiching members are connected to each other via a connecting side plate. The second sandwiching member is a rigid body, one on each side of the cell stacking direction of the cell stack, and a pair on both sides.
(D) In the free state of the multi-cell module, the distance D2 between the pair of second clamping members is larger than the distance D1 between the pair of first clamping members, and when the stack fastening load is applied to the multi-cell module, The multi-cell module, wherein a distance between the pair of second clamping members is smaller than a distance D2 between the pair of second clamping members in a free state of the multi-cell module. The cell multi-cell module according to claim 1 Symbol mounting comprises a metal separator. The multi-cell module according to claim 1 or claim 2 Symbol placement, multiple, stacked, a fuel cell stack granted stack fastening load. 4. The fuel cell stack according to claim 3 , wherein a plate-like member composed of one or more first and second clamping members having a bending rigidity in the cell stacking direction larger than that of the cells is interposed between the cells. The fuel cell stack according to claim 4 , wherein the cell that contacts one surface of the plate-like member and the cell that contacts the other surface bend in opposite directions, and the plate-like member does not bend.

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