JP4737517B2 - Adhesives and fuel cells - Google Patents

Description

  The present invention relates to a fuel cell and a structure of an adhesive body in which a plurality of members made of different materials among members constituting the fuel cell are bonded via an adhesive layer.

For example, a solid polymer electrolyte type fuel cell is configured by laminating a single cell composed of a membrane-electrode assembly (MEA) and a separator. Terminals are fixed to both ends of the stacked single cells. This terminal has a structure including a cover plate fixed to a single cell and a terminal plate having terminals. The cover plate and the terminal plate are formed with a manifold for allowing the reaction gas and the refrigerant to flow. The cover plate and the terminal plate are joined with an adhesive so that the reaction gas and the refrigerant do not flow into the surface from the manifold.
Japanese Patent Laid-Open No. 7-263013

  For example, if the cover plate is made of carbon and the terminal plate is made of metal (such as copper), the cover plate and the terminal plate are made of different materials. In a severe environment, that is, in an environment such as a temperature change due to continuous operation / stop and liquid contact with a refrigerant, or in an environment where the service life is longer than 10 years, sufficient bonding strength may not be obtained. .

  In particular, the terminal plate should be chemically and electrically controlled to prevent an increase in contact resistance with the cover plate due to the formation of an oxide film, etc., and corrosion in the battery environment at the contact area with cooling water or reaction gas. In many cases, surface treatment (for example, Au plating) is performed to improve the stability. In such a case, there are few functional groups for ensuring adhesion, and good adhesion is difficult to obtain. .

  That is, a specific adhesive material is required for the above-mentioned adhesive body. In such a case, as a contradiction, the adhesiveness to other adherends is inferior. There may be cases where universal adhesion to the body is not always obtained.

  The present invention has been made in view of the above circumstances, and an object thereof is to enable bonding between a plurality of members made of different materials with high adhesive force.

  In the present invention, the following means are employed in order to solve the above-described problems. That is, the adhesive body of the present invention is an adhesive body in which a plurality of members made of different materials among members constituting the fuel cell are bonded via an adhesive layer, and a plurality of bonds are formed between the members made of the different materials. A layer is interposed.

  According to such a configuration, it is possible to select an adhesive layer having a high adhesive force with respect to each of different materials. In general, since the adhesive layers have a good adhesive force, the members made of these different materials are bonded to each other with a high adhesive force by interposing a plurality of adhesive layers between the members to be bonded to each other.

  The adhesive layer may be composed of two or more layers in addition to those composed of two layers. For example, in the case of an adhesive layer having a two-layer structure, when sufficient adhesiveness between adhesive layers is not obtained, or when a stronger adhesive force is required, both of the two adhesive layers are increased in order to increase the bonding force between them. Alternatively, a third or fourth adhesive layer having good adhesion may be interposed.

  In the adhesive body, the first member, the first adhesive layer, the second adhesive layer, and the second member of a material type different from the first member are laminated in this order. The bonding force between the first adhesive layer and the first member is greater than the bonding force between the first adhesive layer and the second member, and the second The bonding force between the adhesive layer and the second member may be greater than the bonding force between the second adhesive layer and the first member. Examples of the bonding force include a hydrogen bonding force, a covalent bonding force, an electric bonding force, a mechanical bonding force (anchor effect, etc.), or a combination of two or more of these bonding forces.

  According to such a configuration, the first adhesive layer has a high adhesive force with respect to the first member, and the second adhesive layer has a high adhesive force with respect to the second member. . Thereby, the 1st member and the 2nd member can be joined via the 1st adhesive layer and the 2nd adhesive layer.

  In the above-mentioned adhesive body, the first member may be a cover plate that does not have a fluid groove on at least the surface on the first adhesive layer side, and the second member may be a terminal plate. Further, the first member may be a separator, and the second member may be a frame. Furthermore, the first member may be a separator, and the second member may be another separator made of a material different from that of the first member.

  According to the above configuration, the cover plate and the terminal plate, the separator and the frame, and the separator that are made of different materials are firmly bonded to each other.

  In the above-mentioned adhesive body, the terminal plate and the cover plate have manifolds that communicate with each other, and the first adhesive layer and the second adhesive layer are formed on the periphery of the manifold with the terminal plate and the cover. The plate may be bonded.

  According to such a configuration, the reaction gas and the refrigerant from the manifold are prevented from flowing into the plane between the cover plate and the terminal plate.

  The fuel cell of the present invention has an adhesive body having any one of the above-described configurations.

  According to such a configuration, even when exposed to a severe use environment such as temperature change due to continuous operation and stoppage, liquid contact with a refrigerant, or a long use period, high adhesion between members made of different materials is required. Can be bonded with force.

  In addition to the cover plate and the terminal plate, the dissimilar material members to be bonded to each other include a separator and a frame constituting a single cell, separators of dissimilar materials, and a fuel cell in which a plurality of single cells are stacked. Separators made of different materials between adjacent single cells in the case of a battery stack may be used.

  When a coating (surface treatment) for improving conductivity and corrosion resistance is applied to a plurality of members made of different materials from each other, the adhesion between the members is reduced due to the coating. Therefore, the present invention is a technique particularly suitable for bonding between such members.

  According to the present invention, by bonding members made of different materials through a plurality of adhesive layers, sufficient bonding strength can be maintained even when exposed to a severe environment such as a fuel cell. .

  Next, an embodiment of the present invention will be described with reference to the drawings. In the following, a solid polymer electrolyte type fuel cell will be described, but the present invention is not limited to the following embodiment.

  As shown in FIG. 1, a polymer electrolyte fuel cell 1 has a stack body 3 in which a large number of single cells 2 as basic units are stacked. The fuel cell 1 has a cover plate (first member) 5, 5 ′, a terminal plate (second member) 7, 7 ′, an insulating plate in order on the outside of the unit cell 2 positioned at both ends of the stack body 3. 8, 8 'and end plates 9, 9' are laminated. Reference numeral 6 denotes a terminal provided on the terminal plate 7.

  In the fuel cell 1, for example, a tension plate 11 provided so as to bridge between both end plates 9 and 9 ′ is fixed to the end plates 9 and 9 ′ with bolts 12, so that a predetermined amount is set in the cell stacking direction. The compression force is applied. Note that a pressure plate 13 and a spring mechanism 14 are provided between the end plate 9 ′ on one end side of the stack body 3 and the insulating plate 8 ′, so that fluctuations in the load applied to the single cell 2 are absorbed. It is like that.

  The single cell 2 is not shown in the figure, but an electrolyte membrane made of an ion exchange membrane and a MEA (Membrane Electrode Assembly) made up of a pair of electrodes sandwiching the electrolyte membrane from both sides, a pair of separators that hold the MEA from the outside, It consists of Each separator is made of carbon or metal as a base material and has conductivity.

  Each separator has a fluid flow path for supplying an oxidizing gas (oxygen gas, usually air) or a fuel gas (hydrogen gas) to each electrode. With such a configuration, an electrochemical reaction occurs in the MEA of the single cell 2 and an electromotive force is obtained. Since this electrochemical reaction is an exothermic reaction, the separator is provided with a fluid flow path through which a coolant for cooling the fuel cell flows.

  In the fuel cell 1, a fuel gas manifold 20, an oxidizing gas manifold 20, and a refrigerant manifold 20 are formed so as to penetrate in the cell stacking direction. Is omitted.) These fluid flow path manifolds 20 are formed in the fuel cell 1 by penetrating the end plate 9, the insulating plate 8, the terminal plate 7, the cover plate 5, and the separators of the single cells 2 in the cell stacking direction. ing.

  Each fluid (fuel gas, oxidizing gas, refrigerant) is supplied to each manifold 20a on the inlet side from each fluid pipe 21 provided on the end plate 9 at one end of the fuel cell 1, and passes through each fluid channel formed in the separator. Flowing. Finally, each fluid is discharged from each manifold 20b on the outlet side to each fluid pipe 22 provided on the end plate 9. The end plate 9 ′, the insulating plate 8 ′, the terminal plate 7 ′, and the cover plate 5 ′ on the other end side of the fuel cell 1 are not provided with a manifold.

  In the present embodiment, a fluid channel 5a through which the refrigerant flows is formed on the inner surface of the cover plates 5 and 5 'facing the cell stacking direction, and the fuel cell 1 is cooled by the refrigerant flowing through the fluid channel 5a. However, no fluid flow path (fluid groove) is formed on the surface of the cover plates 5, 5 ′ facing outward in the cell stacking direction, that is, the surface on the first adhesive layer 30 side described later. It has not been.

  FIG. 2 is a cross-sectional view taken along the line AA of FIG. The cover plate 5 is made of carbon material, and the terminal plate 7 is made of metal (copper or the like). Adhesive is applied to the peripheral area (shaded area in the figure) of the manifold 20 in the cover plate 5 so that the fluid does not flow from the manifold 20 into the surface of the cover plate 5 and the terminal plate 7. Be joined. A conductive paste is applied to the region surrounded by the adhesive.

  FIG. 3 is a diagram schematically showing the bonding structure between the cover plate 5 and the terminal plate 7. As shown in the figure, an adhesive layer 25 having a two-layer structure is formed between the cover plate 5 and the terminal plate 7 at the periphery of the manifold. The two-layered adhesive layer 25 includes a first adhesive layer 30 on the cover plate 5 side and a second adhesive layer 31 on the terminal plate 7 side.

  The first adhesive layer 30 may not be able to obtain good adhesion to the terminal plate 7, but has a high adhesion force at least to the cover plate 5 made of carbon material. Adhesives (for example, elastomer-based, epoxy-based, etc.) are employed. The second adhesive layer 31 may not be able to obtain a good adhesive force for the cover plate 5, but has a high adhesive force for at least the terminal plate 7 made of metal. Adhesives (for example, cyanoacrylates, elastomers, etc.) are employed.

  In other words, the bonding force between the first adhesive layer 30 and the cover plate 5 is higher than the bonding force between the first adhesive layer 30 and the terminal plate 7. Further, the bonding force between the second adhesive layer 31 and the terminal plate 7 is higher than the bonding force between the second adhesive layer 31 and the cover plate 5. In addition, it is possible to employ an adhesive that bonds by hydrogen bonding force, covalent bonding force, electrical bonding force, mechanical bonding force (anchor effect, etc.), or a combination of two or more of these bonding forces. is there.

  Since the first adhesive layer 30 and the second adhesive layer 31 are adhesives, they have good adhesiveness.

  By being configured as described above, the cover plate 5 has a good adhesive force with the first adhesive layer 30, and the first adhesive layer 30 has a good adhesion with the second adhesive layer 31. The second adhesive layer 31 has a good adhesive force with the terminal plate 7. Therefore, the cover plate 5 and the terminal plate 7 are bonded with sufficient strength. Therefore, sufficient bonding strength can be obtained even in the severe environment of the fuel cell.

  The cover plate 5 ′ and the terminal plate 7 ′ on the other end side of the fuel cell 1 are not necessarily provided with the above-described bonding structure because no manifold is set, but the bonding structure of the present embodiment is not necessarily used. By adopting it, it is possible to obtain a strong adhesive force as described above.

<Modification>
As a modification of the above embodiment, as shown in FIG. 4, an adhesive layer made of two types of adhesives may be partially formed.

  The terminal plate 37 shown in the figure includes a carbon material portion 37a and a metal portion 37b. Between the carbon material portion 37 a and the cover plate 5, only one adhesive layer is formed by the first adhesive layer 30, and between the metal portion 37 b and the cover plate 5, the first adhesive layer 30. And the second adhesive layer 31 applied to the metal portion 37b to form two adhesive layers. Thus, the application to the terminal plate 37 comprised by a partially different material is also possible.

<Other embodiments>
The present invention is not limited to the above-described embodiment as long as it is used for bonding members of different materials among the members constituting the fuel cell. For example, as shown in FIG. The present invention may be applied to join constituent separators. In the form shown in the figure, when the metal separator (first member) 38 and the resin frame (second member) 39 are bonded, the first adhesive layer 40 and the second adhesive are used. Layer 41 is used.

  As the first adhesive layer 40, it is not necessary to obtain good adhesion to the frame 39, but an adhesive having a high adhesive force to at least a separator 38 made of metal. Is adopted. On the other hand, as the second adhesive layer 41, an adhesive having a high adhesive force at least with respect to the frame 41 made of a resin even though a good adhesive force cannot be obtained with respect to the separator 38. Is adopted.

  By being configured in this way, the separator 38 has a good adhesive force with the first adhesive layer 40, and the first adhesive layer 40 has a good adhesive force with the second adhesive layer 41. The second adhesive layer 41 has a good adhesive force with the frame 39. Therefore, the separator 38 and the frame 39 can be bonded with sufficient strength.

It is sectional drawing of the fuel cell shown as one Embodiment of this invention. It is AA sectional drawing of FIG. It is sectional drawing which showed typically the adhesion structure of a cover plate and a terminal plate. It is sectional drawing which showed typically the adhesion structure of a cover plate and the terminal plate comprised by two types of different materials. It is sectional drawing which showed the adhesion state of the separator and frame which comprise a single cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell main body, 2 ... Single cell, 5 ... Cover plate (1st member), 7 ... Terminal plate (2nd member), 25 ... Adhesive layer, 30 ... 1st adhesive layer, 31 ... 1st 2 adhesive layers, 38 ... separator (first member), 39 ... frame (second member), 40 ... first adhesive layer, 41 ... second adhesive layer

Claims (10)

Among the members constituting the fuel cell, a plurality of members made of different materials are bonded through an adhesive layer,
A plurality of adhesive layers are interposed between the members made of the different materials ,
As the member and the adhesive layer, there are a first member, a first adhesive layer, a second adhesive layer, and a second member of a material type different from the first member in this order. The bonding force between the first adhesive layer and the first member is greater than the bonding force between the first adhesive layer and the second member. An adhesive body in which a bonding force between the second adhesive layer and the second member is larger than a bonding force between the second adhesive layer and the first member. The adhesive body according to claim 1 , wherein the bonding force is a hydrogen bonding force. The adhesive body according to claim 1 , wherein the bonding force is a covalent bonding force. The adhesive body according to claim 1 , wherein the coupling force is an electrical coupling force. The adhesive body according to claim 1 , wherein the bonding force is a mechanical bonding force. The first member is a cover plate that does not have a fluid groove on at least the surface on the first adhesive layer side,
The second member is a terminal plate, the adhesive according to any one of claims 1 to 5. The first member is a separator;
The second member is a frame, the adhesive according to any one of claims 1 to 5. The first member is a separator;
The said 2nd member is an adhesive body in any one of Claims 1-5 which is another separator which consists of a different material from the said 1st member. The terminal plate and the cover plate have manifolds that communicate with each other,
The adhesive body according to claim 6 , wherein the first adhesive layer and the second adhesive layer adhere the terminal plate and the cover plate at a peripheral edge of the manifold. Fuel cell having an adhesive body according to any one of claims 1 to 9.

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