Method for attachment for fuel cells

Abstract

To make it easier for properly attach a gas diffusion layer to an intermediate layer in a step of manufacturing a fuel cell.SOLUTION: In the method for attachment for fuel cells, gas diffusion layers are attached to an intermediate layer in a step of manufacturing a fuel cell with an intermediate layer and gas diffusion layers on both sides of the intermediate layer. The intermediate layer has an electrolyte film and a resin film around the electrolyte film. The method for attachment for fuel cells includes the steps of applying an adhesive to a moisture-cured type on the resin film and bringing the gas diffusion layers into contact with the adhesive to attach the gas diffusion layers and the intermediate layer together.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a method of bonding members constituting a fuel cell to each other.

Background Art

[0002] Among fuel cells, there are those that include, in order from one side, a gas diffusion layer on the anode side, an intermediate layer, and a gas diffusion layer on the cathode side. When a fuel gas as a gas containing hydrogen is supplied to the gas diffusion layer on the anode side and an oxidizing gas as a gas containing oxygen is supplied to the gas diffusion layer on the cathode side of this fuel cell, power generation is performed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventors of the present invention focused on the following problems in the manufacturing stage of such fuel cells. Structurally, in a fuel cell, for one gas diffusion layer, it can be joined to the intermediate layer by hot pressing, but for the other gas diffusion layer, joining to the intermediate layer by hot pressing may not be possible. In this case, it is necessary to bond the other gas diffusion layer to the intermediate layer with an adhesive.

[0005] Specifically, for example, an adhesive is applied to the intermediate layer, and the gas diffusion layer is bonded to the intermediate layer. However, the vicinity of the region where the adhesive is applied may become an adhesive prohibited region. Here, examples of the adhesive prohibited region include the electrode region and the vicinity of the seal region in the fuel cell.

[0006] Specifically, for example, when the adhesive protrudes into the electrode region, it may have an adverse effect on the internal resistance of the fuel cell and the like. Further, for example, when it protrudes near the seal region, it may have an adverse effect on the sealing performance in the fuel cell.

[0007] From the above, it is necessary to precisely control the region where the adhesive is applied. Therefore, it is preferable that the intermediate layer and the gas diffusion layer of the fuel cell be bonded together as appropriately as possible.

[0008] The present invention has been made in view of the above circumstances, and an object thereof is to facilitate appropriately bonding the gas diffusion layer to the intermediate layer in the manufacturing stage of the fuel cell.

Means for Solving the Problems

[0009] The inventors of the present invention have found that the above object can be achieved by appropriately using a moisture-curing adhesive, and thus have arrived at the present invention. The present invention is a method for bonding a fuel cell as described in the following (1) to (3).

[0010] (1) A method for bonding a fuel cell, which comprises an intermediate layer and gas diffusion layers on both sides thereof, in the manufacturing stage of the fuel cell, wherein the gas diffusion layer is bonded to the intermediate layer, the intermediate layer includes an electrolyte membrane and a resin film provided around the electrolyte membrane, a moisture-curing adhesive is applied on the resin film, and then the gas diffusion layer is brought into contact with the adhesive to bond the gas diffusion layer and the intermediate layer with the adhesive. Method for bonding a fuel cell.

[0011] The resin film is difficult to absorb moisture, while the gas diffusion layer is easy to absorb moisture. Therefore, in this configuration, when the moisture-curing adhesive is applied to the resin film, the adhesive is difficult to cure. After that, when the gas diffusion layer is brought into contact with the moisture-curing adhesive, the moisture of the gas diffusion layer makes the adhesive easy to cure. Therefore, it is difficult to cause a situation where the adhesive cures before the gas diffusion layer is brought into contact with the adhesive, or a situation where the adhesive hardly cures even when the gas diffusion layer is brought into contact with the adhesive. For these reasons, it becomes easier to appropriately bond the gas diffusion layer to the intermediate layer.

[0012] (2) After placing the gas diffusion layer on the adhesive, the gas diffusion layer is pressed against the intermediate layer by a pressing device to infiltrate the adhesive into the gas diffusion layer. The bonding method for a fuel cell according to (1) above.

[0013] According to this configuration, by infiltrating the adhesive into the gas diffusion layer, the curing rate of the moisture-curing adhesive can be increased. Furthermore, by the pressing here, the gap between the intermediate layer and the gas diffusion layer can be reduced, and the intermediate layer and the gas diffusion layer can be made closer. Thereby, problems during stacking of a plurality of fuel cells can be suppressed.

[0014] (3) Prepare a jig including a lower jig configured to be able to dispose the intermediate layer on the upper surface and an upper jig configured to be able to dispose the gas diffusion layer on the lower surface. Set it in a state where the gas diffusion layer is disposed on the lower surface of the upper jig, the intermediate layer is disposed on the upper surface of the lower jig, and the adhesive is applied to at least one of the upper surface of the intermediate layer and the lower surface of the gas diffusion layer. From this state, the upper jig is lowered by the pressing device to press the gas diffusion layer against the intermediate layer, thereby infiltrating the adhesive into the gas diffusion layer and bonding the gas diffusion layer to the intermediate layer with the adhesive. The bonding method for a fuel cell according to (2) above.

[0015] According to this configuration, by using such a jig, the gas diffusion layer can be efficiently pressed onto the intermediate layer.

Effects of the Invention

[0016] As described above, according to the configuration of (1) above, in the manufacturing stage of the fuel cell, it becomes easier to appropriately bond the gas diffusion layer to the intermediate layer. Furthermore, according to the configurations of (2) and (3) that cite (1) above, respective additional effects can be obtained.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments at all, and can be appropriately modified and implemented within the scope not departing from the gist of the present invention.

[0019] [First Embodiment] The bonding jig 70 for a fuel cell shown in FIG. 1 is a jig for manufacturing the fuel cell 40. Note that the bonding jig 70 for a fuel cell may be simply read as "jig".

[0020] As shown in FIG. 9, the fuel cell 40 includes, in order from one side, a gas diffusion layer 20a on the anode side, an intermediate layer 30, and a gas diffusion layer 20c on the cathode side. Note that the intermediate layer 30 may be read as "UEA" or "unitized electrode assembly".

[0021] The intermediate layer 30 includes a resin film 32 and an electrolyte membrane 35. The resin film 32 is a film for protecting the edge portion of the electrolyte membrane 35. Specifically, the resin film 32 is composed of, for example, two films: a first resin film on the anode side of the electrolyte membrane 35 and a second resin film on the cathode side of the electrolyte membrane 35. A film window 32w for exposing a portion other than the edge portion of the electrolyte membrane 35 is formed in the resin film 32.

[0022] As shown in FIG. 9, each of the gas diffusion layers 20a, 20c includes a carbon paper 23 and a porous layer 26. The porous layer 26 is provided closer to the intermediate layer 30 side than the carbon paper 23.

[0023] The intermediate layer 30 is larger by one size in plan view than the gas diffusion layer 20c. Therefore, the end portion of the intermediate layer 30 protrudes between the gas diffusion layers 20a, 20c. The gas diffusion layer 20a on the anode side is attached to the intermediate layer 30 by means of hot pressing or the like. On the other hand, the gas diffusion layer 20c on the cathode side is attached to the intermediate layer 30 by an adhesive A.

[0024] Hereinafter, a gas containing hydrogen is referred to as a "fuel gas", and a gas containing oxygen is referred to as an "oxidizing gas". When the fuel cell 40 is in use, the electrodes on both sides of the intermediate layer 30, that is, the anode-side electrode and the cathode-side electrode, are electrically connected via a circuit including a power supply target. In this state, when the fuel gas is supplied to the anode-side gas diffusion layer 20a and the oxidizing gas is supplied to the cathode-side gas diffusion layer 20c, power generation occurs.

[0025] The fuel cell bonding jig 70 shown in FIG. 1 is a jig for bonding the cathode-side gas diffusion layer 20c to the intermediate layer 30 in the manufacturing stage of the fuel cell 40 shown in FIG. 9 above. Hereinafter, the cathode-side gas diffusion layer 20c is simply referred to as the "gas diffusion layer 20c". This fuel cell bonding jig 70 shown in FIG. 1 includes an upper jig 50, a lower jig 60, a receiving plate 67 shown in FIG. 5, and a retainer 68.

[0026] As shown in FIG. 1, the lower jig 60 includes a plurality of guide shafts 65, a positioning recess 62, and a plurality of positioning pins 63.

[0027] Each guide shaft 65 extends upward from the upper surface of the lower jig 60. Each guide shaft 65 passes through a guided hole 56 provided in the upper jig 50. Thus, the upper jig 50 is attached to the lower jig 60 so as to be vertically displaceable via a plurality of guide shafts 65.

[0028] As shown in FIG. 2, the positioning recess 62 is a recess for positioning the gas diffusion layer 20c with respect to the lower jig 60. The positioning recess 62 has substantially the same shape and size as the gas diffusion layer 20c in a top view. As shown in FIG. 4, the receiving plate 67 is configured to be installable within the positioning recess 62.

[0029] As shown in Fig. 5, each positioning pin 63 is a pin for positioning the intermediate layer 30 with respect to the lower jig 60. Specifically, each positioning pin 63 extends upward from the upper surface of the lower jig 60. A plurality of insertion holes 33 are provided in the resin film 32 of the intermediate layer 30. Each positioning pin 63 positions the intermediate layer 30 with respect to the lower jig 60 by inserting through the corresponding insertion hole 33. Note that each of these positioning pins 63 may be read as a "positioning portion".

[0030] The rib 68 is configured to be attachable on a portion of the upper surface of the intermediate layer 30 that does not face the gas diffusion layer 20c in the bonding state StL described later.

[0031] As shown in Fig. 1, a rod of a pressing device 80 such as an air cylinder is attached to the upper jig 50. The upper jig 50 is configured to be movable up and down in the vertical direction by this pressing device 80.

[0032] As shown in Fig. 2, the upper jig 50 includes a suction mechanism 55. The suction mechanism 55 includes a porous body 551 and a suction system 552. The porous body 551 is provided on the lower surface of the upper jig 50. When the suction mechanism 55 is turned on, the suction system 552 sucks the air inside the porous body 551. Thereby, as shown in Fig. 3, the gas diffusion layer 20c is adsorbed to the lower surface of the upper jig 50.

[0033] Hereinafter, as shown in Fig. 5, a state in which the gas diffusion layer 20c is disposed on the lower surface of the upper jig and the intermediate layer 30 is disposed on the upper surface of the lower jig 60, and the adhesive A is applied to the upper surface of the intermediate layer 30 is referred to as a "bonding state StL". Specifically, in the bonding state StL of the present embodiment, the adhesive A is linearly applied along the film window 32w to both side portions sandwiching the film window 32w in the resin film 32. The fuel cell bonding jig 70 is configured to be set in the bonding state StL.

[0034] From the bonded state StL, as shown in FIG. 6, when the upper jig 50 is lowered by the pressing device 80, as shown in FIGS. 7 and 8, the porous layer 26 in the gas diffusion layer 20c is pressed against the adhesive A on the intermediate layer 30.

[0035] Next, a bonding method for a fuel cell using the fuel cell bonding jig 70 shown above will be described.

[0036] First, the operator prepares the fuel cell bonding jig 70 shown in FIG. 1.

[0037] Next, the operator prepares the gas diffusion layer 20c shown in FIG. 2 and places the gas diffusion layer 20c on the lower jig 60 with the porous layer 26 side facing down. At this time, the gas diffusion layer 20c is placed inside the positioning recess 62. Thereby, the gas diffusion layer 20c is positioned at a fixed position on the upper surface of the lower jig 60.

[0038] From that state, the operator turns on the suction mechanism 55 as shown in FIG. 3 to suck the gas diffusion layer 20c onto the lower surface of the upper jig 50. Thereby, the gas diffusion layer 20c is arranged at a fixed position on the lower surface of the upper jig 50.

[0039] Next, the operator sets a predetermined receiving plate 67 in the positioning recess 62 as shown in FIG. 4.

[0040] Next, the operator prepares the intermediate layer 30 shown in FIG. 5. A moisture-curing adhesive A is applied to a predetermined portion on the upper surface of the resin film 32 in the intermediate layer 30. Specifically, the adhesive A is linearly applied along the film window 32w to both side portions sandwiching the film window 32w in the resin film 32. Note that the manufacturing environment at this time is about 50% RH (23°C).

[0041] Next, the operator places the intermediate layer 30 on the upper surface of the lower jig 60 as shown in FIG. 5. At this time, the positioning pin 63 is inserted through the insertion hole 33 of the intermediate layer 30. Thereby, the intermediate layer 30 is positioned at a fixed position on the upper surface of the lower jig 60. At this time, the receiving plate 67 is positioned directly below the adhesive A.

[0042] As described above, the above-described bonding state StL is achieved. That is, the gas diffusion layer 20c is disposed on the lower surface of the upper jig 50, and the intermediate layer 30 is disposed on the upper surface of the lower jig 60, and the adhesive A is applied to the upper surface of the intermediate layer 30. Next, the operator attaches the retainer 68 on the portion of the upper surface of the intermediate layer 30 that does not face the gas diffusion layer 20c in this bonding state StL.

[0043] Next, as shown in FIG. 6, the operator operates the pressing device 80 to lower the upper jig 50. Thereby, as shown in FIG. 7, the gas diffusion layer 20c adsorbed on the lower surface of the upper jig 50 comes into contact with the adhesive A on the upper surface of the intermediate layer 30. As the upper jig 50 further descends from that state, as shown in FIG. 8, the gas diffusion layer 20c is pressed against the intermediate layer 30. Thereby, while the adhesive A penetrates into the porous layer 26 of the gas diffusion layer 20c, the gas diffusion layer 20c is bonded to the intermediate layer 30 with the adhesive A.

[0044] Thereafter, the operator turns off the suction device 55, releases the pressing by the pressing device 80 to raise the upper jig 50, and takes out the bonded body F of the gas diffusion layer 20c and the intermediate layer 30 from the fuel cell bonding jig 70. The anode-side gas diffusion layer 20a shown in FIG. 9 is bonded to the intermediate layer 30 in the bonded body F by hot pressing.

[0045] The configuration and effects of the present embodiment are summarized below.

[0046] As shown in FIG. 5, after being set in the aforementioned state StL for bonding, as shown in FIG. 6, the upper jig 50 is lowered, and as shown in FIGS. 7 and 8, the gas diffusion layer 20c can be bonded to the intermediate layer 30 with the adhesive A just by pressing the gas diffusion layer 20c against the intermediate layer 30. Therefore, compared with the case where such a bonding jig 70 for fuel cells is not used, it becomes easier to efficiently bond the intermediate layer 30 and the gas diffusion layer 20c.

[0047] As shown in FIG. 6, the upper jig 50 is attached to the lower jig 60 so as to be displaceable in the vertical direction via a guide shaft 65 extending in the vertical direction. Therefore, the guide shaft 65 makes it easier to correctly align the upper jig 50 with respect to the lower jig 60. Also in this regard, it becomes easier to efficiently bond the gas diffusion layer 20c to the intermediate layer 30. Further, it becomes easier to bond the gas diffusion layer 20c to the intermediate layer 30 at the correct relative position with high accuracy.

[0048] As shown in FIG. 2, the upper jig 50 includes a suction mechanism 55. Due to the suction by the suction mechanism 55, as shown in FIG. 3, the gas diffusion layer 20c is configured to be disposed on the lower surface of the upper jig 50. Therefore, due to the suction, the gas diffusion layer 20c can be disposed on the lower surface of the upper jig 50 against gravity. Also in this regard, it becomes easier to efficiently bond the gas diffusion layer 20c to the intermediate layer 30.

[0049] As shown in FIG. 1, a positioning recess 62 for positioning the gas diffusion layer 20c is provided on the upper surface of the lower jig 60. Therefore, as shown in FIG. 2, after positioning the gas diffusion layer 20c in the positioning recess 62 in the lower jig 60, as shown in FIG. 3, the gas diffusion layer 20c can be disposed at a fixed position on the lower surface of the upper jig 50 just by sucking the gas diffusion layer 20c on the lower surface of the upper jig 50. Also in this regard, it becomes easier to efficiently bond the gas diffusion layer 20c to the intermediate layer 30 and it becomes easier to bond them at the correct relative position with high accuracy.

[0050] As shown in FIG. 5, positioning pins 63 are provided on the upper surface of the lower jig 60 to position the intermediate layer 30. The positioning pins 63 make it easier to place the intermediate layer 30 at a fixed position on the lower surface of the upper jig 50. Also in this regard, it becomes easier to efficiently bond the gas diffusion layer 20c to the intermediate layer 30 and to bond them at the correct relative position with high accuracy.

[0051] As shown in FIG. 5, the retainer 68 is configured to be attachable on the portion of the upper surface of the intermediate layer 30 that does not face the gas diffusion layer 20c in the aforementioned bonding state StL. The retainer 68 can suppress the undulation of the intermediate layer 30. Also in this regard, it becomes easier to efficiently bond the gas diffusion layer 20c to the intermediate layer 30 and to bond them at the correct relative position with high accuracy.

[0052] Further, when the adhesive A shown in FIG. 8 protrudes from between the gas diffusion layer 20c and the intermediate layer 30 to the retainer 68, the adhesive A adheres to the retainer 68. Therefore, it is possible to prevent the adhesive A from protruding into the adhesive prohibition area, which will be described later, beyond the retainer 68.

[0053] The resin film 32 shown in FIG. 7 is difficult to absorb moisture, whereas the porous layer 26 of the gas diffusion layer 20c is easy to absorb moisture. Therefore, as shown in FIG. 5, when the moisture-curing adhesive A is applied to the resin film 32, the adhesive A is difficult to cure. Thereafter, as shown in FIG. 7, when the porous layer 26 of the gas diffusion layer 20c is brought into contact with the moisture-curing adhesive A, the adhesive A is likely to cure due to the moisture in the porous layer 26. Therefore, it is less likely to result in a situation where the adhesive A cures before the gas diffusion layer 20c is brought into contact with it, or a situation where the adhesive A does not cure easily even when the gas diffusion layer 20c is brought into contact with it. Thereby, it becomes easier to appropriately bond the gas diffusion layer 20c to the intermediate layer 30.

[0054] Therefore, it becomes easier to suppress the total amount of the adhesive A to be applied, and it becomes easier to suppress the application width of the adhesive A. Therefore, when the gas diffusion layer 20c is bonded to the resin film 32, it is possible to prevent the adhesive A from protruding from the desired application area. Therefore, it is possible to suppress the adhesive A from protruding into the adhesive prohibited area in the fuel cell 40.

[0055] Specifically, examples of the adhesive prohibited area referred to here include, for example, the electrode area and the vicinity of the seal area in the fuel cell 40 shown in FIG. 9. The electrode area is the area on both sides that sandwich the electrolyte membrane 35 in its thickness direction. On the other hand, the seal area is the bonding area between a plurality of cover members (not shown) that cover the intermediate layer 30 and the gas diffusion layers 20a and 20c. Therefore, the vicinity of the seal area is the vicinity of the protruding portion from between the gas diffusion layers 20a and 20c in the intermediate layer 30. From these facts, when the adhesive A is applied, the electrode area and the vicinity of the seal area are located on both sides that sandwich the application area in the horizontal direction.

[0056] From the above, according to the present embodiment, by using the moisture-curing type adhesive A, it is possible to suppress the adhesive A from protruding into the electrode area and the vicinity of the seal area on both sides thereof. Therefore, it is possible to suppress the adverse effects such as the adhesive A protruding into the electrode area and affecting the internal resistance of the fuel cell 40, and the adverse effects such as the adhesive A protruding into the vicinity of the seal area and affecting the sealing performance of the fuel cell 40.

[0057] As shown in FIG. 7, after placing the gas diffusion layer 20c on the adhesive A, as shown in FIG. 8, by pressing the gas diffusion layer 20c against the intermediate layer 30, the adhesive A is infiltrated into the porous layer 26 of the gas diffusion layer 20c. By this infiltration, the curing rate of the moisture-curing type adhesive A can be increased. Further, by the pressing here, the gap between the intermediate layer 30 and the gas diffusion layer 20c can be reduced, and the intermediate layer 30 and the gas diffusion layer 20c can be made closer. Thereby, problems during stacking of a plurality of fuel cells 40 can be suppressed.

[0058] [Other Embodiments] The embodiments shown above can be modified as follows, for example.

[0059] In the order reverse to that of the first embodiment, after joining the anode-side gas diffusion layer 20a shown in FIG. 9 to the intermediate layer 30 by hot pressing, the above fuel cell bonding method may be carried out, and the cathode-side gas diffusion layer 20c may be bonded to the intermediate layer 30 with the adhesive A.

[0060] The above fuel cell bonding method may be automatically carried out by a robot. Instead of the positioning pin 63 shown in FIG. 5, positioning portions other than pins, such as groove portions and locking portions, may be provided. Instead of the adsorption mechanism 72 shown in FIG. 3, a fastener for fixing the gas diffusion layer 20c to the lower surface of the upper jig 50 may be provided.

Explanation of Reference Numerals

[0061] 20c Cathode-side gas diffusion layer 30 Intermediate layer 32 Resin film 35 Electrolyte membrane 40 Fuel cell 50 Upper jig 55 Adsorption mechanism 60 Lower jig 62 Positioning recess 63 Positioning pin (positioning portion) 65 Guide shaft 68 Gavar 80 Air cylinder (pressing device) A Adhesive StL Bonding state (state)

Claims

1. A method for bonding a fuel cell, which comprises an intermediate layer and gas diffusion layers on both sides thereof, in a manufacturing stage of the fuel cell, the method comprising bonding the gas diffusion layer to the intermediate layer, wherein the intermediate layer comprises an electrolyte membrane and a resin film provided around the electrolyte membrane, applying a moisture-curing adhesive on the resin film, and then bringing the gas diffusion layer into contact with the adhesive to bond the gas diffusion layer and the intermediate layer with the adhesive. A method for bonding a fuel cell.

2. After placing the gas diffusion layer on the adhesive, pressing the gas diffusion layer against the intermediate layer with a pressing device to penetrate the adhesive into the gas diffusion layer. The method for bonding a fuel cell according to Claim 1.

3. Preparing a jig including a lower jig configured to be able to dispose the intermediate layer on an upper surface thereof and an upper jig configured to be able to dispose the gas diffusion layer on a lower surface thereof, setting the gas diffusion layer on the lower surface of the upper jig and the intermediate layer on the upper surface of the lower jig, and applying the adhesive to at least one of an upper surface of the intermediate layer and a lower surface of the gas diffusion layer, from this state, lowering the upper jig by the pressing device to press the gas diffusion layer against the intermediate layer, thereby penetrating the adhesive into the gas diffusion layer and bonding the gas diffusion layer to the intermediate layer with the adhesive. The method for bonding a fuel cell according to Claim 2.

Images