JP2008226682A - Fuel cell, its manufacturing method, and fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deformation of a separator in a formation process of a cell of a fuel cell. <P>SOLUTION: This fuel cell is provided with: an MEA 10 formed by respectively arranging an anode 12 and a cathode 13 on both sides of an electrolyte 11; separators 14 and 15 arranged on both sides of the MEA; and support members 2 mounted on a circumferential part of the separator 14, and having rib parts 2a arranged between the separators 14 and 15. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidizing gas, and more particularly to a seal structure between separators.

  2. Description of the Related Art Generally, a solid polymer electrolyte type fuel cell is configured by stacking cells (single cells) each including a membrane-electrode assembly (MEA) and a separator. The MEA includes an electrolyte membrane composed of an ion exchange membrane, an electrode (anode) composed of a catalyst layer disposed on one surface of the electrolyte membrane, and an electrode (cathode) composed of a catalyst layer disposed on the other surface of the electrolyte membrane. It is out. The separator is formed of a material having low permeability to the fuel gas and the oxidizing gas and having conductivity, and a gas flow path for supplying the fuel gas or the oxidizing gas to the MEA on both sides thereof, And the flow path for distribute | circulating a cooling water is each formed.

In addition, a fuel cell having a stack structure forms a cell stack by a method of holding a single cell with an adhesive or sealing by sandwiching a gasket, and further, terminals (electrode plates) at both ends in the cell stacking direction. ), Insulators, and end plates are arranged, the cell stack is clamped in the cell stacking direction, and is fixed by a bolt and a fastening member (for example, a tension plate) extending in the cell stacking direction outside the cell stack. Is done.
JP 2006-32041 A JP 2005-78826 A JP 2004-178777 A

  By the way, when forming a single cell using an adhesive, usually, as shown in FIG. 4, two separators 91 and 92 and MEA 93 are sandwiched by a flat jig 90 and an adhesive 94 is disposed. Both are bonded by applying pressure. However, the end portions of the separators 91 and 92 that are not in contact with the MEA 93 do not receive a reaction force from the MEA 93 even when the surface pressure is applied by the jig 90. Therefore, the end portions of the separators 91 and 92 cannot be maintained in a planar shape along the jig 90 and are warped inward. Then, when a plurality of cells are stacked, the end portion is opened between adjacent cells, and the compression margin of the gasket sandwiched between the cells may be insufficient. As a result, even if the cell stack is tightened with a bolt or the like, the sealing performance between adjacent separators cannot be maintained.

  As a related technique, Patent Document 1 prevents the warpage of the separator when adhering the separator and the MEA by devising the shape of the separator. Patent Document 2 discloses that the adhesiveness of the separator is improved by performing a heat treatment after forming a cell including the separator and the MEA. Furthermore, Patent Document 3 discloses disposing a seal member on the outer periphery of the separator. However, if a heat treatment is incorporated into the process of forming the fuel cell or a process for producing a separator with a seal is provided separately, the entire process of manufacturing the fuel cell becomes complicated.

  Then, in view of said problem, an object of this invention is to prevent the deformation | transformation of the separator in the formation process of a fuel cell.

  In order to achieve the above object, a fuel cell according to one aspect of the present invention includes an ion exchanger in which an anode and a cathode are respectively disposed on both sides of an electrolyte, and a first electrode disposed on both sides of the ion exchanger. 1 and a second separator, and a support member attached to an outer peripheral portion of the first separator and having a rib disposed between the first and second separators.

  With this configuration, when surface pressure is applied to the entire two separators sandwiching the ion exchanger, the end portions of the separators receive reaction force from the ribs of the support member. Thereby, it can suppress that the edge part of a separator deform | transforms toward the inner side of a cell, sticking an ion exchanger and a separator.

  Here, the support member may further include a gasket protruding to the opposite side of the rib with the first separator interposed therebetween. By integrating the support member and the gasket, it is easy to secure a region to which the support member is attached, and it is possible to simplify the cell formation process by reducing the number of components used.

  The ion exchanger may be fixed to the first and second separators by an adhesive disposed at least around the ion exchanger. Thereby, an ion exchanger and its interface can be sealed twice with an adhesive and a rib.

  A fuel cell stack according to one aspect of the present invention includes an ion exchanger in which an anode and a cathode are respectively disposed on both sides of an electrolyte, and a first and a second that are respectively disposed on both sides of the ion exchanger. A plurality of cells arranged in a stacked manner, including separators, and attached to the outer periphery of the first separator in each cell, and arranged between the first and second separators in each cell A support member having a rib; and a gasket that seals a boundary between a first separator in one cell of adjacent cells and a second separator in the other cell.

  By adopting such a configuration, it is possible to suppress the end of the separator from warping toward the inside of the cell, so that it is possible to secure a compression margin of the gasket disposed between adjacent cells.

  Here, by forming the gasket integrally with the support member, it is easy to secure a mounting region for the support member, and it is possible to reduce the number of components and facilitate the cell formation process.

  A fuel cell manufacturing method according to one aspect of the present invention includes a fuel including an ion exchanger in which an anode and a cathode are disposed on both sides of an electrolyte, and first and second separators disposed on both sides, respectively. A method for manufacturing a battery, the step (a) of attaching a support member having a rib disposed between the first and second separators to an outer peripheral portion of the first separator, and the first and second components. A step (b) of disposing an ion exchanger and an adhesive between the separators, and disposing the first and second separators between two flat plate jigs, and the first and second separators. A step of fixing the ion exchanger and the first and second separators by applying a surface pressure to the first and second separators in a state where each of them receives a reaction force from the rib (c) )

  Thus, deformation of the separator end can be suppressed by applying a surface pressure to the entire separator while applying a reaction force by the rib to the end of the separator.

  According to the present invention, it is possible to secure a compression margin of a gasket disposed between adjacent cells when the cells are stacked by suppressing the end of the separator from being deformed toward the inside of the cell. Is possible. Therefore, it becomes possible to maintain the sealing performance at the boundary between adjacent cells. Moreover, it becomes possible to improve the sealing performance in a cell by making each cell the double seal structure by an adhesive agent and a rib.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same reference number is attached | subjected to the same component and description is abbreviate | omitted.
FIG. 1 is a cross-sectional view showing a fuel cell according to an embodiment of the present invention. This fuel cell is a solid polymer electrolyte type fuel cell, and includes a cell 1 including an MEA (membrane-electrode assembly) 10 and two separators 14 and 15, and a support member 2. The MEA 10 and the separators 14 and 15 are joined by the adhesive 3.

The MEA 10 is an ion exchanger including an electrolyte membrane 11 made of a polymer material ion exchange membrane, and an anode 12 and a cathode 13 sandwiching the electrolyte membrane 11 from both sides. The anode 12 and the cathode 13 are formed of, for example, a porous carbon material (diffusion layer) to which a catalyst such as platinum (Pt) is bound.
In such a cell 1, electricity is generated by an electrochemical reaction between a fuel gas (for example, hydrogen gas) supplied to the anode 12 and an oxidizing gas (for example, air) supplied to the cathode 13.

  The separators 14 and 15 are made of a conductive material having a gas impermeability or a gas hardly permeability such as a metal such as aluminum or stainless steel, in addition to carbon or a hard resin having conductivity. Further, the separator 14 is formed with a gas flow path 14 a for flowing fuel gas to be supplied to the anode 12 and a flow path 14 b for flowing cooling water for cooling the cell 1. On the other hand, the separator 15 is formed with a gas flow path 15a for flowing an oxidizing gas to be supplied to the cathode 13 and a cooling water flow path 15b.

  The support member 2 includes a rib portion 2a that protrudes toward the inside (MEA 10 side) of the cell 1, a gasket portion 2b that protrudes on the opposite side, and a connection portion 2c that connects the two. It is attached to the outer periphery of one separator (the separator 14 in FIG. 1). The support member 2 is formed of a material having relatively high elasticity or adhesiveness, such as silicone rubber or EPDM (ethylene-propylene-diene rubber). The rib generally refers to a protrusion that is attached to prevent deformation.

  The rib portion 2a has a height corresponding to at least the thickness of the MEA 1 (the interval between the separators 14 and 15), and is provided to suppress deformation of the separators 14 and 15 when the cell 1 is formed. ing. Further, after the formation of the cell 1, it acts as a sealing member for preventing gas leakage in the gas flow paths 14a and 14b.

  The adhesive 3 fixes the MEA 10 and the separators 14 and 15, and acts as a seal member that prevents gas leakage from the gas flow paths 14 a and 15 a after the cell 1 is formed.

FIG. 2 is a schematic diagram for explaining a process of forming the cell shown in FIG.
When forming the cell 1, first, the MEA 1 and the adhesive 3 are arranged between the separator 14 to which the support member 2 is attached and the separator 15. Then, the separators 14 and 15 are sandwiched between the flat jigs 20 and a surface pressure is applied thereto, thereby joining the separators 14 and 15 and the MEA 1 in close contact with each other. In that case, the area | region which is contacting the rib part 2a among the separators 14 and 15 receives the reaction force equivalent to the surface pressure applied from the rib part 2a, and is each pressed against the jig | tool 20. Thereby, the deformation | transformation of the edge part of the separators 14 and 15 is suppressed. 2 shows a state in which the gasket portion 2b of the support member 2 is compressed by the separator 14 and the jig 20.

Referring to FIG. 1 again, the gasket portion 2b of the support member 2 is provided to maintain a sealing property between adjacent cells when the cells 1 are stacked.
Referring now to FIG. 3, the cell stack is fixed by fastening a plurality of cells 1 with bolts, tension plates or the like (not shown). In that case, the gasket part 2b (refer FIG. 1) is compressed to such an extent that the surface of the separator 15 between the adjacent cells 1 and the surface of the separator 14 mutually contacts substantially. Thereby, the flow paths 14b and 15b provided in each separator are united to form a tubular flow path, and the flow paths 14b and 15b are sealed by the compressed gasket portion 2b.

  As described above, according to the present embodiment, the surface pressure is applied to the entire separator while the reaction force is applied to the end portions of the separators 14 and 15 from the rib portion 2a, so that the end portions are not deformed so much. Cell 1 can be formed. Thereby, since the planar shape on the outer surface of the cell 1 can be maintained, when the plurality of cells 1 are stacked, the gap at the end between adjacent cells can be reduced. Accordingly, a sufficient margin for compression of the gasket portion 2b can be secured, so that the sealing performance at the boundary between adjacent cells can be maintained. Moreover, in each cell 1, since the double seal structure can be formed by the adhesive 3 and the rib portion 2a, it becomes possible to improve the sealing performance with respect to the MEA 10 and the gas flow paths 14a and 15a.

  Further, since the support member 2 having the rib portion 2a and the gasket portion 2b has a simple shape, a mold for forming the support member can be easily manufactured, and the completed support member 2 can be used as a separator. 14 can be easily attached. Further, by integrally forming the rib portion 2a and the gasket portion 2b, it is easy to secure a mounting region for the rib portion 2a, and the gasket portion 2b is also attached from the outer peripheral portion of the separator 14. 14 can be reduced.

Here, the material which forms the supporting member 2 may use the same material by the rib part 2a and the gasket part 2b, and may change it for every part. For example, for the rib portion 2a, in order to obtain a sufficient reaction force when forming the cell 1, for example, a rubber material having a hardness H _S of about 60 or more and a relatively large Young's modulus is used, and the gasket portion 2b. For example, a material that has a hardness H _S of about 45 or less and is easily compressed to some extent may be used.

  In addition, the height of the rib portion 2a is preferably about the thickness of the MEA 1 before the surface pressure is applied to the cell 1 or more depending on the material, but it is preferable that the thickness of the MEA 1 It is possible to make it slightly shorter. That is, as long as the amount of displacement caused by the separators 14 and 15 being warped inside the cell 1 is within a range that can be absorbed by the compression margin of the gasket portion 2b, it is possible to maintain the sealing performance at the boundary between adjacent cells. It is.

  In the present invention described above, the ion exchanger is not limited to the MEA in which the electrode is formed on the membrane-shaped solid polymer electrolyte as described above, but may be in other shapes or other states. In addition, the ion exchanger may be composed of only the polymer electrolyte or may include other components as long as it includes at least the polymer electrolyte.

It is sectional drawing which shows the structure of the fuel cell which concerns on one Embodiment of this invention. It is a figure for demonstrating the process of forming the cell shown in FIG. It is sectional drawing which shows the cell laminated body which laminated | stacked the cell shown in FIG. It is a figure for demonstrating the process of forming a cell by the conventional method.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cell, 2 ... Support member, 2a ... Rib part, 2b ... Gasket part, 3 ... Adhesive, 10 ... MEA, 11 ... Electrolyte membrane, 12 ... Anode, 13 ... Cathode, 14, 15 ... Separator, 20 ... Oji Ingredients

Claims (6)

An ion exchanger in which an anode and a cathode are respectively arranged on both sides of the electrolyte;
First and second separators respectively disposed on both sides of the ion exchanger;
A support member attached to the outer periphery of the first separator and having a rib disposed between the first and second separators;
A fuel cell comprising:   2. The fuel cell according to claim 1, wherein the support member further includes a gasket protruding to the opposite side of the rib with the first separator interposed therebetween.   The fuel cell according to claim 1 or 2, wherein the ion exchanger is fixed to the first and second separators by at least an adhesive disposed around the ion exchanger. Each includes an ion exchanger in which an anode and a cathode are arranged on both sides of the electrolyte, and first and second separators arranged on both sides of the ion exchanger, and a plurality of layers arranged in a stacked manner. Cell,
A support member attached to the outer periphery of the first separator in each cell, and having a rib disposed between the first and second separators in each cell;
A gasket for sealing a boundary between a first separator in one of adjacent cells and a second separator in the other cell;
A fuel cell stack comprising:   The fuel cell stack according to claim 4, wherein the gasket is formed integrally with the support member. A method for producing a fuel cell, comprising: an ion exchanger having an anode and a cathode respectively disposed on both sides of an electrolyte; and first and second separators disposed on both sides of the ion exchanger,
Attaching a support member having a rib disposed between the first and second separators to the outer periphery of the first separator;
A step (b) of disposing an ion exchanger and an adhesive between the first and second separators;
The first and second separators are disposed between two flat jigs, and each of the first and second separators receives a reaction force from the rib of the support member, (C) fixing the ion exchanger and the first and second separators by applying a surface pressure to the second separator;
A method for manufacturing a fuel cell comprising:

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