JP2009283390A - Cell of fuel battery and fuel battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a malfunction when forming a gasket 20 by restraining generation of exfoliation between an electrolyte membrane 11 and an electrode layer 12 when forming a membrane-electrode assembly 10; and to restraining generation of a cross leak between both electrode layers. <P>SOLUTION: An outer periphery of electrode layers 12, 12 are integrally stitched to the electrolyte layer 11 by an insulating thread 17. Furthermore, a resin for a gasket 20 is entered so as to penetrate inside the electrode layer 12 by exceeding the stitched section. Consequently, holes generated on the electrolyte membrane 11 caused by stitching are closed by the resin, and generation of the cross leak of the gas is prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell and a fuel cell configured by sandwiching the fuel cell with a separator.

  A polymer electrolyte fuel cell is known as one of the fuel cells. FIG. 4 is a cross-sectional view showing an example thereof. A membrane electrode assembly 3 including an electrode layer 2 in which a catalyst layer and a diffusion layer are laminated in this order on both surfaces of the electrolyte membrane 1 is formed. A fuel cell is formed by laminating separators 5 and 5 having a gas flow path 4. An electrolyte membrane 1a protrudes around the electrode layer 2, and an appropriate resin material is filled as a gasket (seal member) 6 between the protruding electrolyte membrane portion 1a and the separator 5 so as to be integrated. Sealing is applied.

  In such a process of forming the membrane / electrode assembly 3, peeling may occur at the interface between the electrolyte membrane and the electrode layer due to the influence of the difference in thermal expansion of each member and the stress due to the expansion and contraction accompanying the absorption and dehydration of the electrolyte membrane. . When such peeling occurs, problems occur in the molding of the gasket, the sealing performance becomes insufficient, and the molding yield of the membrane electrode assembly decreases. In order to cope with this, Patent Document 1 describes that the peripheral edge of the electrode layer is sewn to the electrolyte membrane with a fixed polymer electrolyte thread and hot-pressed. Further, in Patent Document 2, by forming a through hole in the protruding portion of the electrolyte membrane, the fixing state between the electrolyte membrane and the gasket is improved, and the outer peripheral edge of the electrode layer is impregnated with the resin for the gasket. Is described.

JP 2003-17087 A JP 2007-188757 A

  As described in Patent Document 1, the periphery of the electrode layer is sewn to the electrolyte membrane using a thread, thereby suppressing the separation between the electrolyte membrane and the electrode layer due to the swelling and shrinkage of the electrolyte membrane. be able to. However, as a result of stitching with a thread, a communication hole is formed between both electrode layers, and when power is generated, there is a possibility that a gas cross-leak may occur through a gap between the communication hole and the suture thread. Further, as described in Patent Document 2, when a gasket is molded, a high sealing property is ensured between the membrane electrode assembly and the separator by impregnating the outer periphery of the electrode layer with a resin for the gasket. be able to. However, as described above, when peeling occurs at the interface between the electrolyte membrane and the electrode layer in the process of forming the membrane / electrode assembly, the gasket may not be sufficiently formed and the sealing performance may not be ensured.

  The present invention has been made in view of the circumstances as described above, and suppresses the occurrence of peeling between the electrolyte membrane and the electrode layer during the formation of the membrane electrode assembly, thereby eliminating the problems during the molding of the gasket. In addition, the fuel cell and the separator can improve the molding yield, suppress the occurrence of cross-leakage between both electrode layers, and ensure sufficient sealing performance between the membrane electrode assembly and the separator. It is an object of the present invention to disclose a fuel cell that is sandwiched.

  The fuel cell according to claim 1 includes at least a membrane electrode assembly including an electrode layer composed of a catalyst layer and a diffusion layer on both surfaces of an electrolyte membrane, and a seal member formed around the membrane electrode assembly. The outer peripheral portion of the electrode layer is integrally sewn to the electrolyte membrane by an insulating thread, and the seal member penetrates to the inside of the electrode layer beyond the sewn portion. It is characterized by being.

  In the fuel cell described above, the outer peripheral portion of the electrode layer is integrally sewn to the electrolyte membrane by the insulating thread, and the electrolyte membrane and the electrode layer are changed due to the dimensional change of the electrolyte membrane when the membrane electrode assembly is formed. It is possible to prevent the peeling at the interface with. In addition, as a result of stitching, it is not necessary to heat press to integrate the electrolyte membrane and the electrode layer, so that no thermal history is added to the electrolyte membrane during the production of the membrane electrode assembly, and the electrolyte membrane Can be prevented from peeling off at the interface between the electrode layer and the electrode layer. Thereby, a sealing member such as a gasket can be formed around the membrane electrode assembly as designed. Further, since the seamed area is further covered by the resin material constituting the sealing member to the inner side (the center part side of the electrode layer), gas cross-leakage occurs through the through-hole generated during sewing during power generation. There is nothing. Therefore, according to the present invention, a fuel battery cell having high performance and excellent durability can be obtained.

  The fuel cell according to claim 2 is the fuel cell according to claim 1, wherein the diffusion layer in the electrode layer is sized to extend from the periphery of the catalyst layer, and the extension portion of the diffusion layer In the region, sewing with the insulating thread is performed.

  In the fuel cell according to claim 1, the catalyst layer and the diffusion layer forming the electrode layer may have the same size. In the fuel cell according to the second aspect, the diffusion layer has a size extending from the periphery of the catalyst layer, and the diffusion layer is in direct contact with the electrolyte membrane by sewing. The diffusion layer is generally a carbon fiber sheet or paper, and when integrated by hot pressing, the carbon fiber of the diffusion layer may pierce and damage the electrolyte membrane, resulting in a short circuit. In the fuel cell, since the diffusion layer and the electrolyte membrane are integrated by stitching regardless of hot pressing, it is possible to greatly reduce the damage to the electrolyte membrane due to the fiber sticking.

  The fuel cell according to claim 3 is the fuel cell according to claim 2, wherein a sealing material made of a resin film is inserted between the extension portion of the diffusion layer and the electrolyte membrane. The sealing material is also sewn together by the insulating thread. Although there is no restriction | limiting in particular in the resin film of a sealing material, A PEN resin film, a PET resin film, etc. are suitable. The thickness of the sealing material is preferably the same as or slightly thicker than the catalyst layer constituting the electrode layer.

  In the fuel cell according to the third aspect, it is possible to further reliably prevent the electrolyte membrane from being damaged by inserting the sealing material made of the resin film.

  In the invention according to claim 4, the fuel cell according to any one of claims 1 to 3 is sandwiched by a separator, and the membrane electrode assembly and the separator are sealed by the seal member. A fuel cell characterized by the following.

  As described above, in the fuel cell according to the present invention, it is possible to reliably suppress the separation between the electrolyte membrane and the electrode layer when the membrane electrode assembly is formed. Such a sealing member can be formed as designed. Therefore, the molding yield of the fuel battery cell is improved. Furthermore, since it is possible to reliably suppress the occurrence of gas cross-leakage between both electrodes during power generation, a high-performance and durable fuel battery cell and a fuel battery having the separator sandwiched between them can be obtained.

Hereinafter, the present invention will be described by way of embodiments with reference to the drawings.
[First form]
In the first embodiment shown in FIG. 1, the fuel battery cell A <b> 1 includes a membrane electrode assembly 10 and a gasket 20. As shown in FIG. 1 (a), a membrane electrode assembly 10 includes an electrolyte membrane 11 having proton conductivity having, for example, a sulfonic acid group as a proton exchange group, and an electrode layer 12 laminated on both surfaces thereof. Is done. The electrode layer 12 includes a catalyst layer 13 facing the electrolyte membrane 11 and a diffusion layer 14 laminated on the outside thereof.

  The catalyst layer 13 is formed of a catalyst mixture including an electrolyte resin and a catalyst-carrying conductor. A platinum-based metal is mainly used for the catalyst, and carbon powder is mainly used for a conductor supporting the catalyst. The diffusion layer 14 is mainly composed of carbon paper or carbon cloth.

  In the membrane electrode assembly 10 shown in FIG. 1, the diffusion layer 14 has a region 15 that extends outward from the periphery of the catalyst layer 13, and the electrolyte membrane 11 has a size that further protrudes from the periphery of the diffusion layer 14. ing. A sealing material 16 made of a resin film such as PEN or PET is inserted between the region 15 extending from the catalyst layer 13 of the diffusion layer 14 and the electrolyte membrane 11. The outer edge reaches the outer edge of the electrolyte membrane 11.

  The membrane electrode assembly 10 is produced by, for example, screen-printing and drying an ink-like mixture obtained by mixing an appropriate solvent with a catalyst mixture containing an electrolyte resin and a catalyst-carrying conductor on both surfaces of the electrolyte membrane 11. The layer 13 can be formed, and then the diffusion layer 14 can be laminated and hot-pressed.

  Next, as shown in FIG. 1 (b), in the membrane / electrode assembly 10 thus prepared, portions of the upper and lower diffusion layers 14 and 14, regions 15 and 15 extending from the catalyst layers 13 and 13. Are sewn together with the sealing materials 16 and 16 and the electrolyte membrane 11 using an insulating thread 17 made of an insulating material such as polyester resin, acrylic resin, PEN, PET, or PTFE. As a result, the electrolyte membrane 11, the electrode layer 12, and the sealing material 16 are stitched together, and the expansion and contraction of the electrolyte membrane 11 causes the peeling between the electrolyte membrane 11 and the diffusion layer 14 constituting the electrode layer 12. Be blocked.

  Next, the membrane electrode assembly 10 integrally stitched with the insulating thread 17 as described above is put in a mold (not shown), and a gasket 20 as a seal member is injected around the membrane electrode assembly 10 by, for example, silicone resin. By molding, the fuel cell A1 is obtained. At that time, as shown in FIG. 1C, the resin constituting the gasket 20 reaches the inner position 21 from the stitching position by the insulating thread 17, that is, the central portion side of the electrode layer 12. Then, the gasket 20 is injection molded. This completely prevents the fuel gas and the oxidant gas from cross-leaking through the hole in the electrolyte membrane 11 made of the insulating yarn 17. Further, the members of the membrane electrode assembly 10 are integrally stitched together by the insulating thread 17, so that no peeling occurs between the members in the manufacturing process, and the gasket 20 is molded without any inconvenience as designed. .

  Further, as described above, the integration of the electrode layer 12 with the electrolyte membrane 11 is performed only by stitching with the insulating thread 17 without performing hot pressing, so that damage to the electrolyte membrane 11 can also be prevented. Furthermore, in this embodiment, the sealing material 16 made of a resin film is inserted between the region 15 extending from the catalyst layer 13 of the diffusion layer 14 and the electrolyte membrane 11, and high sealing performance can also be achieved.

  Although a conventionally known separator is disposed and sandwiched on both sides of the fuel cell A1 shown in FIG. 1C, a fuel cell (not shown) is formed, but formed around the membrane electrode assembly 10. The gasket 20 is as intended, and high sealing performance is ensured between the membrane electrode assembly 10 and the separator 20. As a result, a high-performance and durable fuel cell can be obtained.

[Second form]
FIG. 2 shows a second embodiment of the fuel battery cell according to the present invention. In this fuel cell A2, the size of the catalyst layer 13 and the diffusion layer 14 constituting the electrode layer 12 are the same, and therefore the fuel cell A2 does not have the sealing material 16, so that the fuel of the first embodiment shown in FIG. It is different from the battery cell A1. Other configurations are the same as those of the fuel cell A1 of the first embodiment, and are denoted by the same reference numerals.

  As shown in FIG. 2 (a), a membrane electrode assembly 10 is formed in substantially the same manner as in the case of the fuel cell A1, and then the periphery of the electrode layer 12 is insulated as shown in FIG. 2 (b). The upper and lower electrode layers 12 and 12 and the electrolyte membrane 11 are integrated by sewing with a thread 17. Next, it is put in a molding die (not shown), and a fuel cell A2 is formed by injection molding a gasket 20 as a seal member around the membrane electrode assembly 10 using, for example, silicone resin.

[Third embodiment]
FIG. 3 shows a third embodiment of the fuel battery cell according to the present invention. The fuel cell A3 is the same as the fuel cell A1 of the first embodiment shown in FIG. 1 in that the diffusion layer 14 is larger than the catalyst layer 13 and the electrolyte membrane 11 is larger than the diffusion layer. This is different from the fuel cell A1 of the first embodiment in that the sealing material 16 made of a resin film is not provided between the region 15 extending from the catalyst layer 13 of the diffusion layer 14 and the electrolyte membrane 11. Other configurations are the same as those of the fuel cell A1 of the first embodiment, and are denoted by the same reference numerals.

  Also in this embodiment, as shown in FIG. 3A, the membrane electrode assembly 10 is formed in substantially the same manner as in the case of the fuel cell A1, and then, as shown in FIG. 3B, the diffusion layer 14 The portions of the extended region 15 are sewn together with an insulating thread 17. Thereby, the diffusion layers 14 and 14 constituting the upper and lower electrode layers 12 and 12 and the electrolyte membrane 11 are integrated. Although the diffusion layer 14 made of carbon fiber is in direct contact with the electrolyte membrane 11, it does not require integration by hot pressing, and therefore the electrolyte membrane 11 is not damaged. Next, it is put in a molding die (not shown), and a fuel cell A3 is obtained by injection molding a gasket 20 as a seal member around the membrane electrode assembly 10 using, for example, silicone resin.

  In this case as well, a conventionally known separator is disposed and sandwiched on both sides of the fuel cells A2 and A3 to form a fuel cell (not shown). However, as in the case of the fuel cell A1, the membrane electrode assembly The gasket 20 formed around 10 is as intended, and high sealing performance is ensured between the membrane electrode assembly 10 and the separator 20. Therefore, also in the second and third embodiments, a high-performance and durable fuel cell can be obtained.

FIGS. 1A, 1B, and 1C are schematic views for explaining a fuel cell of a first embodiment according to the present invention together with a production process thereof. FIGS. 2A, 2B and 2C are schematic views for explaining a fuel cell of a second embodiment according to the present invention together with a production process thereof. FIGS. 3A, 3B, and 3C are schematic views for explaining a fuel cell of a third embodiment according to the present invention together with a production process thereof. The figure for demonstrating an example of a polymer electrolyte fuel cell.

Explanation of symbols

A1 to A3 ... fuel cell, 10 ... membrane electrode assembly, 11 ... electrolyte membrane, 12 ... electrode layer, 13 ... catalyst layer, 14 ... diffusion layer, 15 ... region where the diffusion layer extends beyond the catalyst layer, 16 ... Seal material made of a resin film, 17 ... Insulating thread, 20 gasket (seal member), 21 ... Part where the seal member enters the electrode layer beyond the stitched portion

Claims (4)

A fuel cell comprising at least a membrane electrode assembly comprising an electrode layer comprising a catalyst layer and a diffusion layer on both surfaces of an electrolyte membrane, and a seal member formed around the membrane electrode assembly,
The outer peripheral portion of the electrode layer is integrally sewn to the electrolyte membrane with an insulating thread, and the seal member extends beyond the sewn portion to the inside of the electrode layer. Battery cell.   The said diffusion layer in an electrode layer is a magnitude | size extended from the circumference | surroundings of a catalyst layer, and the sewing-in with the said insulating thread is performed in the area | region of the said extension part of a diffusion layer, It is characterized by the above-mentioned. The fuel cell described in 1.   A sealing material made of a resin film is inserted between the extension part of the diffusion layer and the electrolyte membrane, and the sealing material is sewn together with the insulating thread including the sealing material. Item 3. The fuel cell according to Item 2.   The fuel cell according to claim 1, wherein the fuel cell is sandwiched between separators, and the membrane electrode assembly and the separator are sealed by the seal member.

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