JP2007059256A - Sealing structure for fuel cell and fuel cell having it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing structure for a fuel cell capable of preventing separation of a gasket; and to provide a fuel cell having the sealing structure for a fuel cell. <P>SOLUTION: This sealing structure 20 for a fuel cell includes an adhesive layer 12 arranged on the surface of a fuel cell constituent member 24 and the gasket 11 attached to the surface of the fuel cell constituent member 24 through the adhesive layer 12, and is so structured that the surface of the adhesive layer 12 that may contact a fluid in the fuel cell 200 is covered with corrosion resistant materials 13, 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell seal structure and a fuel cell including the fuel cell seal structure, and more particularly to a fuel cell seal structure and a fuel cell seal structure capable of preventing peeling of a gasket. The present invention relates to a fuel cell provided.

  A fuel cell has an electric property in a membrane electrode assembly (hereinafter referred to as “MEA (Membrane Electrode Assembly)”) including an electrolyte layer and electrodes (cathode and anode) disposed on both sides of the electrolyte layer. Electric energy generated by chemical reaction is taken out. Among fuel cells, a polymer electrolyte fuel cell (hereinafter referred to as “PEFC (Polymer Electrolyte Fuel Cell”)) can be operated in a low temperature region. In addition, PEFC has been attracting attention as an optimal power source for electric vehicles and portable power sources because of its high energy conversion efficiency, short start-up time, and small and lightweight system.

  A single cell of PEFC includes an electrolyte membrane, a cathode and an anode including at least a catalyst layer, and a separator, and a theoretical electromotive force thereof is 1.23V. However, since such low electromotive force is insufficient as a power source for electric vehicles and the like, normally, a single cell is laminated in series to form a laminated body, and end plates or the like are formed at both ends of the laminated body in the lamination direction. A stack-type fuel cell is used.

An electrochemical reaction that is a source of electricity generation in a fuel cell proceeds in the following steps. First, hydrogen delivered to the anode through a groove formed in the separator is decomposed into hydrogen ions and electrons in the presence of the catalyst.
Anode side: H ₂ → 2H ⁺ + 2e ⁻ (Formula 1)
The generated hydrogen ions pass through the electrolyte membrane, which is an ionic conductor, and move to the cathode. Since the electrolyte membrane has a property of allowing only ions to pass through, the generated electrons cannot pass through the electrolyte membrane and move to the air electrode through an external circuit. In a fuel cell, electricity is generated by such movement of electrons. On the other hand, the oxygen delivered to the cathode reacts with hydrogen ions and electrons that have moved to the air electrode, thereby generating water.
Cathode side: 2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O (Formula 2)

  On the other hand, in a single cell of PEFC, OH radicals and the like are also generated by the side reaction of the above reaction. It is known that when OH radicals are generated in a single cell, a part of the electrolyte membrane or the like is damaged by the OH radicals and the acid is eluted.

  Thus, in PEFC, a hydrogen-containing gas (hereinafter sometimes referred to as “hydrogen”) is used for the anode, and an oxygen-containing gas (hereinafter sometimes referred to as “air”) is used for the cathode. By supplying each, an electrochemical reaction is caused in the MEA. Therefore, in order to efficiently generate electric energy, it is necessary to prevent leakage of the reaction gas (gas leakage). It is also necessary to prevent the acid produced during PEFC operation from eluting out of the system. Therefore, PEFC prevents leakage of reaction gas and acidic solution by providing a seal structure including a gasket.

  So far, several techniques related to a fuel cell seal structure have been disclosed. For example, Patent Document 1 discloses a technique relating to a fuel cell gasket, which is characterized in that a gasket is bonded to a collector electrode frame (corresponding to the separator) via a thermosetting adhesive. According to this technique, the power generation efficiency of the fuel cell can be maximized because the gasket is strongly and stably sealed by the gasket.

  Patent Document 2 includes a sheet-like gasket mounting member having a sticking function on one surface, and a gasket body made of a rubber-like elastic material integrated with the sheet-like gasket mounting member. A technique related to a gasket, which is attached to a mating attachment member by an attaching function of the attachment member, is disclosed. According to such a technique, since the gasket body is bonded to the mating mounting member via the sheet-shaped gasket mounting member, there is no possibility of cracking or the like even if the mating mounting member is a low-strength material or a thin plate. The mating attachment member and the gasket can be easily integrated.

Further, Patent Document 3 discloses a technology relating to a fuel cell gasket in which a liquid rubber cured product (corresponding to the above gasket) is formed on both sides or one side of a separator obtained by plating a metal thin plate with a corrosion-resistant material. It is disclosed. According to such a technique, the liquid rubber cured product is firmly fixed to the separator without applying an adhesive to the plated separator, so that the manufacturing process can be simplified. .
JP 2004-55276 A JP 2003-56704 A JP 2001-332275 A

  However, in the technique disclosed in Patent Document 1, the gasket is bonded through an adhesive. For this reason, if the adhesive deteriorates due to contact with the reaction gas flowing in the single cell, water generated by an electrochemical reaction, cooling water to cool the separator, etc., the adhesive function of the gasket is lowered and the gasket is There existed a problem that it peeled from a separator and the sealing performance fell easily. Further, even in the technique disclosed in Patent Document 2, since the gasket is attached via an adhesive or adhesive having a sticking function, when the adhesive deteriorates, the gasket is peeled off from the separator, and the sealing performance is likely to be lowered. There was a problem. Further, in the technique disclosed in Patent Document 3, since the liquid rubber cured product is fixed to the separator without using an adhesive, the liquid rubber cured product is peeled off and sealed by an external force applied to the single cell. There was a problem that there is a possibility that the property may be impaired.

  Then, this invention makes it a subject to provide the fuel cell provided with the sealing structure for fuel cells which can prevent peeling of a gasket, and the said sealing structure for fuel cells.

In order to solve the above problems, the present invention takes the following means. That is,
The invention described in claim 1 includes an adhesive layer disposed on the surface of the fuel cell constituent member, and a gasket attached to the surface of the fuel cell constituent member via the adhesive layer, and a fluid in the fuel cell The above-mentioned problem is solved by a fuel cell sealing structure characterized in that the surface of the adhesive layer that can come into contact with the surface is coated with a corrosion-resistant material.

  Here, as a specific example of the fuel cell constituent member on which the adhesive layer is disposed, a separator or the like can be cited. Further, the adhesive constituting the adhesive layer is not particularly limited as long as the gasket can be adhered to the fuel cell constituent member. Specific examples thereof include an acrylic adhesive, a silicon adhesive, and the like. Can be mentioned. Further, the gasket is not particularly limited as long as a sealed space can be formed in the fuel cell. For example, a rubber material or the like can be used. Specific examples of the rubber material include fluorine rubber (FPM), silicon rubber, ethylene propylene rubber (EPDM), and the like. In addition, the corrosion resistant material is not particularly limited as long as it has corrosion resistance capable of preventing corrosion damage of the adhesive layer, and for example, a resin material, a rubber material, a metal, or the like can be used. Specific examples of resin materials include fluororesins, phenol resins, epoxy resins, and specific examples of rubber materials include FPM, EPDM, chloropyrene rubber (CR), nitrile rubber (NBR), and specific examples of metals. Examples thereof include gold and platinum. In addition, the fluid in the fuel cell means a fluid that may exist in a single cell or the like, specifically, a reactive gas such as hydrogen or air, water (steam) generated by an electrochemical reaction, and It means a cooling medium such as LLC that should cool the separator.

  According to a second aspect of the present invention, in the fuel cell seal structure according to the first aspect, the adhesive layer, and at least a part of the gasket and the corrosion-resistant material are disposed in the recess of the fuel cell constituent member. It is characterized by.

  Here, the form of the concave portion of the fuel cell constituent member is not particularly limited as long as the adhesive layer, the gasket, and the corrosion-resistant material can be disposed. Moreover, the recessed part formed in order to arrange | position an adhesive bond layer, a gasket, and a corrosion-resistant material may be sufficient, and an adhesive bond layer, a gasket, and a corrosion-resistant material exist in the recessed part previously existing on the surface of a fuel cell structural member. May be arranged.

  According to a third aspect of the present invention, in the fuel cell seal structure according to the first or second aspect, the constituent element for the fuel cell is a separator.

  A fourth aspect of the present invention solves the above-described problems by a fuel cell comprising the fuel cell seal structure according to any one of the first to third aspects.

  According to the first aspect of the present invention, the adhesive layer to be bonded and fixed to the fuel cell constituent member is covered with the corrosion-resistant material. Therefore, the corrosion resistant material can prevent corrosion damage of the adhesive layer, and can maintain the adhesiveness of the adhesive over a long period of time. Therefore, according to the first aspect of the present invention, it is possible to provide a fuel cell seal structure capable of preventing the peeling of the gasket over a long period of time.

  According to the second aspect of the present invention, since the adhesive layer and at least a part of the gasket and the corrosion-resistant material are disposed in the concave portion of the fuel cell constituent member, the corrosion-resistant material can be fixed to the adhesive surface. It becomes easy. Therefore, according to the second aspect of the present invention, it is possible to provide a fuel cell seal structure that can easily prevent peeling of the gasket over a long period of time.

  According to the third aspect of the present invention, since the separator has high strength among the fuel cell constituent members, it is easy to form the recess.

  According to the fourth aspect of the invention, the fuel cell seal structure capable of preventing the peeling of the gasket over a long period of time maintains the sealing performance in the fuel cell, thereby improving the power generation efficiency. It becomes possible to provide the obtained fuel cell.

  PEFC generates electricity using hydrogen and air (hereinafter sometimes collectively referred to as “reactive gas”) supplied to a single cell, and water is generated during the power generation. OH radicals and the like are also generated by side reactions. The OH radicals and the like generated in the single cell deteriorate the electrolyte components provided in the constituent members (electrolyte membrane, catalyst layer, etc.) in the single cell, and a trace amount of acid is eluted by this deterioration. Therefore, the single cell has an acidic environment, and a fluid such as a reaction gas or water exists in the acidic environment. Furthermore, since the separator of PEFC is cooled by a cooling medium such as cooling water, this cooling medium may also exist in the single cell.

  In order to improve the power generation efficiency of the fuel cell, it is necessary to efficiently use the reaction gas supplied to the single cell, and the utilization efficiency of the reaction gas can be improved by sealing the single cell. Therefore, conventionally, a technique for sealing a single cell using a gasket attached to a separator is known, and the gasket is generally fixed via an adhesive. However, as described above, since the single cell has an acidic environment in which several types of fluids exist, the adhesive may be corroded by such fluids. When the adhesive is damaged (deteriorated), the gasket is easily peeled off from the separator, and the sealing performance of the single cell is likely to be lowered. In addition, although the form which comprises an adhesive agent with a highly corrosion resistant material is also considered, it is difficult to maintain the corrosion resistance of the said material over a long period of time in the environment which contacts the fluid in a single cell directly.

  On the other hand, a technique for directly fixing a gasket to a separator without using an adhesive has been proposed so far. However, in such a form, the adhesive strength of the gasket is likely to be lowered, so that it is difficult to maintain the sealing property of a single cell. There is.

  The present invention has been made from such a viewpoint, and the gist of the present invention is that the surface of an adhesive layer used when attaching a gasket to a fuel cell component is coated with a corrosion-resistant material, and the adhesive layer and the fuel cell It is to prevent contact with the fluid. With this form, the adhesive layer is prevented from deteriorating, and the adhesive ability of the adhesive can be maintained over a long period of time. Therefore, it becomes possible to provide a fuel cell seal structure that can prevent the gasket from being peeled off, and a fuel cell that can improve power generation performance can be provided.

  Hereinafter, the present invention will be specifically described with reference to the drawings. Hereinafter, the fuel cell sealing structure may be simply referred to as “sealing structure”, and the adhesive layer may be simply referred to as “adhesive”.

1. First Embodiment FIG. 1 is a cross-sectional view schematically showing a part of a fuel cell having a fuel cell seal structure according to the first embodiment of the present invention, and an example of the seal structure. The direction is the stacking direction of the separators. FIG. 1A is an enlarged cross-sectional view showing a part of a fuel cell (hereinafter sometimes referred to as “single cell”) having the fuel cell seal structure according to the first embodiment. is there. On the other hand, FIG. 1 (B) is a cross-sectional view schematically showing an example of the fuel cell seal structure according to the first embodiment, and shows an enlarged portion where the seal structure is provided. Hereinafter, the fuel cell seal structure according to the first embodiment will be described with reference to FIG.

  As shown in FIG. 1A, the single cell 100 according to the first embodiment includes seal structures 10 and 10 formed at the end of the separator 14. On the other hand, the single cell 100 includes an electrolyte membrane 1, an MEA 4 including an anode catalyst layer 2a and a cathode catalyst layer 3a disposed on both sides of the electrolyte membrane 1, and an anode diffusion layer 2b disposed outside the MEA 4. And the cathode diffusion layer 3b. Reactive gas supply paths 6a and 6a are provided on the surfaces of the separators 14 and 14 'disposed on the outer side of the multilayer body 5 on the side of the multilayer body 5, respectively. , ..., 6b, 6b, ... are formed. Then, the laminate 5 is sandwiched between the separators 14 and 14 ', and the space (hereinafter referred to as "sealed") where the laminate 5 is present by the separators 14 and 14' and the seal structures 10 and 10 formed in the separator 14. The unit cell 100 is manufactured by sealing the space.

  On the other hand, as shown in FIG. 1B, the seal structure 10 according to the first embodiment includes an adhesive 12 disposed on the surface of the separator 14 that is a constituent member of the single cell 100, and the adhesive 12 interposed therebetween. The gasket 11 attached to the surface of the separator 14 and the corrosion-resistant materials 13 and 13 to be coated on the surface of the adhesive 12 are provided. The surfaces of the gasket 11 and the adhesive 12 are covered with the corrosion-resistant materials 13 and 13. Has been. Therefore, the fluid (hydrogen, air, generated water, etc.) existing in the sealed space can be in direct contact with the gasket 11, while the adhesive 12 is covered with the corrosion resistant materials 13, 13. As long as the surface of the adhesive 12 is covered with 13, 13, the fluid and the adhesive 12 are not in direct contact. Therefore, according to the seal structure 10, it is possible to prevent corrosion damage of the adhesive 12 due to the fluid in the sealed space, and the adhesive ability of the adhesive 12 is maintained. It is possible to prevent over and maintain the sealing performance of the sealed space over a long period of time. And since the fuel cell 100 is equipped with the seal structures 10 and 10 of such a form, the supply efficiency of a reactive gas improves. Therefore, it becomes possible to provide the fuel cell 100 which can improve power generation efficiency by setting it as the form provided with the seal structures 10 and 10 concerning 1st Embodiment.

2. Second Embodiment FIG. 2 is a cross-sectional view schematically showing a part of a fuel cell having a fuel cell seal structure of the present invention according to a second embodiment, and an example of the form of the seal structure. The direction is the stacking direction of the separators. FIG. 2A is an enlarged cross-sectional view of a part of the fuel cell having the fuel cell seal structure according to the second embodiment. On the other hand, FIG. 2B is a cross-sectional view schematically showing an example of the fuel cell seal structure according to the second embodiment, and shows an enlarged portion where the seal structure is provided. 2, members having the same configuration as the fuel cell and seal structure shown in FIG. 1 are denoted by the same reference numerals as those used in FIG. 1, and description thereof will be omitted as appropriate.

  As shown in FIG. 2A, in the fuel cell 200 according to the second embodiment, the seal structures 20 and 20 are disposed in the recesses 24 a and 24 a formed at the end of the separator 24. On the other hand, the unit cell 200 includes the MEA 4 including the electrolyte membrane 1, the anode catalyst layer 2a, and the cathode catalyst layer 3a, and the stacked body 5 including the anode diffusion layer 2b and the cathode diffusion layer 3b. Reactive gas supply passages 6c, 6c,..., 6b, 6b,... Are formed on the surfaces of the separators 24 and 14 'disposed on the laminated body 5 side, respectively. Then, the unit cell 200 is manufactured by sealing the space in which the stacked body 5 exists by the separators 24 and 14 ′ and the sealing structures 20 and 20 provided in the separator 24.

  On the other hand, as shown in FIG. 2B, the seal structure 20 according to the second embodiment includes an adhesive 12, a gasket 11, and corrosion-resistant materials 13 and 13. Thus, if each component of the seal structure 20 is disposed in the recess 24a of the separator, the surface of the adhesive 12 can be easily covered with the corrosion-resistant materials 13 and 13. Therefore, according to the seal structure 20 according to the second embodiment, it is possible to easily prevent the corrosion damage of the adhesive 12, and thus it is possible to easily prevent the gasket 11 from peeling off. And since the fuel cell 200 is equipped with the sealing structures 20 and 20 of this form, the supply efficiency of a reactive gas improves. Therefore, it becomes possible to provide the fuel cell 200 which can improve power generation efficiency by setting it as the form provided with the seal structures 20 and 20 concerning 2nd Embodiment.

  In the present invention, the corrosion resistant material is used to prevent deterioration of the adhesive, and the gasket is bonded to the separator via the adhesive. Therefore, the corrosion-resistant material according to the present invention only needs to have at least corrosion resistance, and adhesion (tackiness) is not required in principle. However, when the corrosion resistant material is provided in a form that can cover the surfaces of the gasket and the adhesive as in the first embodiment and the second embodiment, a corrosion resistant material having adhesiveness may be used. By using such a form of the corrosion-resistant material, it becomes possible to fix the gasket on the separator via the adhesive and the corrosion-resistant material, so that the peeling of the gasket can be more effectively prevented. And it becomes possible to provide a fuel cell provided with the said sealing structure for fuel cells.

  The corrosion-resistant material used in the present invention is not particularly limited as long as it can withstand the environment in the fuel cell and can cover the surface of the adhesive even during operation of the fuel cell. Specific examples of the corrosion-resistant material according to the present invention include resin materials such as fluororesin, phenol resin, and epoxy resin, rubber materials such as FPM, EPDM, CR, and NBR, metals such as gold and platinum, and the like.

  In the present invention, the method for disposing the corrosion resistant material on the surface of the adhesive is not particularly limited as long as it can be fixed on the surface of the adhesive. Specific examples of the arrangement method include a spray coating method and a method of arranging using a syringe or the like.

  In the present invention, the adhesive is not particularly limited as long as the gasket can be fixed to the surface of a fuel cell component (for example, a separator) in a form that can form a sealed space. For example, it is possible to use the adhesive etc. which were used in the conventional seal structure. Specific examples of the adhesive according to the present invention include acrylic adhesives and silicon adhesives.

  Furthermore, in the present invention, the gasket is not particularly limited as long as a sealed space can be formed in the fuel cell. For example, a rubber material or the like can be used. Specific examples of the rubber material include FPM, silicon rubber, EPDM, and the like.

It is sectional drawing which shows roughly the fuel cell provided with the sealing structure for fuel cells concerning 1st Embodiment, and the form example of the said sealing structure. It is sectional drawing which shows roughly the fuel cell provided with the sealing structure for fuel cells concerning 2nd Embodiment, and the form example of the said sealing structure.

Explanation of symbols

10, 20 Seal structure for fuel cell 11 Gasket 12 Adhesive 13 Corrosion resistant material 14, 24 Separator 100, 200 Fuel cell

Claims (4)

An adhesive layer disposed on the surface of the fuel cell component, and a gasket attached to the surface via the adhesive layer;
A sealing structure for a fuel cell, wherein a surface of the adhesive layer that can come into contact with a fluid in the fuel cell is coated with a corrosion-resistant material. 2. The fuel cell seal structure according to claim 1, wherein at least a part of the adhesive layer, the gasket, and the corrosion-resistant material are disposed in a recess of the fuel cell component. 3. The fuel cell sealing structure according to claim 1, wherein the fuel cell component is a separator. A fuel cell comprising the seal structure according to claim 1.

Images