Method for manufacturing fuel cell

Abstract

To suppress a partial change in the thickness of an adhesive when joining a plate member and a separator with the adhesive.SOLUTION: A method of manufacturing a fuel cell in which a plate member having a membrane electrode assembly and a frame supporting the membrane electrode assembly is joined to one of a pair of separators sandwiching the plate member includes a first step of applying an adhesive in a line shape having a predetermined width on a first surface of the frame facing the separator, and a second step of forming a cured portion having a higher hardness than the adhesive at an end portion of the adhesive in a width direction. The method includes a third step of bringing the curing portion and the second surface into contact with each other by relatively moving the plate member suspended with the first surface facing downward, and a fourth step of performing positioning by relatively moving the plate member with respect to the separator in a direction parallel to the second surface in a state where the curing portion is in contact with the second surface.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a fuel cell. [Background technology]

[0002] Patent Document 1 discloses a method for manufacturing a single fuel cell, which joins a separator to a MEGA plate comprising a membrane electrode gas diffusion layer assembly and a frame member made of a thermoplastic resin joined to the periphery of the assembly. In this manufacturing method, the separator is hot pressed against the MEGA plate, and the thermoplastic resin of the frame member is melted and fused to the separator, thereby joining the MEGA plate and the separator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-18963 Summary of the Invention [Problem to be solved by the invention]

[0004] The plate member including the membrane electrode assembly and the separator can also be bonded using an adhesive. For example, the plate member and the separator can be bonded by contacting a plate member coated with adhesive and suspended with a separator placed on a stage. When bonding the plate member and the separator in this manner, gravity can cause the plate member to bend, and the edge of the adhesive can come into contact with the separator before positioning. When the plate member is moved relative to the separator for positioning while the edge of the adhesive is in contact with the separator, the adhesive is pulled, causing a problem of partial changes in thickness. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] According to one aspect of the present disclosure, there is provided a method for manufacturing a fuel cell, which includes joining a plate member having a membrane electrode assembly and a frame supporting the membrane electrode assembly to one of a pair of separators sandwiching the plate member, the method comprising: a first step of applying an adhesive in a linear pattern having a predetermined width to a first surface of the frame facing the separator; a second step of creating a hardened portion of the adhesive at a widthwise end of the adhesive, the plate member having a second surface facing the first surface and facing upward, the plate member being suspended with the first surface facing downward relative to the separator, the second surface facing upward, to bring the hardened portion into contact with the second surface; and a fourth step of positioning the plate member relative to the separator in a direction parallel to the second surface, with the hardened portion in contact with the second surface. According to this form of fuel cell manufacturing method, even if the plate member is moved relative to the separator for positioning purposes while the end of the adhesive is in contact with the separator, a hardened portion is created at the end of the adhesive, thereby preventing the thickness of the adhesive from changing. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is an exploded perspective view showing the schematic configuration of a fuel cell. [Figure 2] 10 is a flowchart showing a method for manufacturing a fuel cell. [Figure 3] FIG. 2 is a diagram showing a state in which an adhesive is applied to a first surface. [Figure 4] The figure shows a state in which hardened portions have been created at the widthwise ends of the adhesive. [Figure 5] FIG. 4 is a schematic diagram showing how a plate member and an anode separator are joined together. DETAILED DESCRIPTION OF THE INVENTION

[0008] A. First embodiment: FIG. 1 is an exploded perspective view showing the schematic configuration of a fuel cell 100. The fuel cell 100 is configured as a polymer electrolyte fuel cell. The fuel cell 100 receives a supply of fuel gas and oxidant gas, and generates electricity through an electrochemical reaction between them. For example, the fuel gas is hydrogen, and the oxidant gas is air. The fuel cell 100 includes a plate member 10 and a pair of separators, an anode separator 20 and a cathode separator 30, that sandwich the plate member 10.

[0009] The plate member 10 includes a power generation section 11 and a frame 12. The frame 12 has a rectangular frame shape with an opening 13 in the center. The frame 12 is made of thermoplastic resin. The power generation section 11 is disposed in the opening 13 of the frame 12. The frame 12 supports the outer periphery of the power generation section 11.

[0010] The power generation unit 11 is composed of a membrane electrode gas diffusion layer assembly (MEGA). The membrane electrode gas diffusion layer assembly includes a membrane electrode assembly (MEA) and a gas diffusion layer. The membrane electrode assembly includes an electrolyte membrane, an anode catalyst layer disposed on one side of the electrolyte membrane, and a cathode catalyst layer disposed on the other side of the electrolyte membrane. The electrolyte membrane is a proton-conductive ion-exchange membrane formed of a solid polymer material, such as a fluororesin containing perfluorocarbon sulfonic acid, and exhibits good electrical conductivity in a wet state. The anode catalyst layer and the cathode catalyst layer are formed by coating conductive particles, such as carbon particles, carrying a catalyst such as platinum or a platinum alloy, with a proton-conductive polymer electrolyte. Gas diffusion layers are disposed on both sides of the membrane electrode assembly. Hereinafter, the gas diffusion layer disposed on the anode catalyst layer side will be referred to as the anode diffusion layer, and the gas diffusion layer disposed on the cathode catalyst layer side will be referred to as the cathode diffusion layer. Gas diffusion layers are made of gas-permeable and electrically conductive materials such as carbon cloth or carbon paper.

[0011] The anode separator 20 is disposed on the surface of the plate member 10 on which the anode diffusion layer is disposed. The surface of the anode separator 20 facing the plate member 10 is provided with flow channel grooves 21 recessed in a direction away from the power generation unit 11. The cathode separator 30 is disposed on the surface of the plate member 10 on which the cathode diffusion layer is disposed. The surface of the cathode separator 30 facing the plate member 10 is provided with flow channel grooves 31 recessed in a direction away from the power generation unit 11. The anode separator 20 and the cathode separator 30 are made of gas-impermeable and electrically conductive materials, and are formed, for example, from carbon materials such as dense carbon made by compressing carbon particles to make them gas-impermeable, or from metal materials such as press-formed stainless steel or titanium steel.

[0012] Six manifold holes 41 to 46 that form manifolds are formed in the frame 12 and each separator. Fuel gas flows through the manifold holes 43 and 44. Coolant flows through the manifold holes 42 and 45. Oxidant gas flows through the manifold holes 41 and 46.

[0013] The frame 12 has a plurality of slits 49 formed near the manifold holes 41, 43, 44, and 46, penetrating the frame 12 in the stacking direction. Here, the stacking direction is the direction in which the plate members 10 and the separators are stacked. The slits 49 extend from near the outer peripheries of the manifold holes 41, 43, 44, and 46 toward near the outer periphery of the opening 13. The slit 49 near the manifold hole 44 of the frame 12 is formed in a position overlapping both the manifold hole 44 of the anode separator 20 and the flow channel groove 21 formed in the anode separator 20. In other words, the slit 49 near the manifold hole 44 of the frame 12 communicates between the manifold hole 44 and the flow channel groove 21. Similarly, the slit 49 near the manifold hole 43 of the frame 12 communicates between the manifold hole 43 and the flow channel groove 21. As a result, the fuel gas flowing through the manifold hole 44 flows into the flow channel 21 via the slits 49 near the manifold hole 44, and then flows from the flow channel 21 into the manifold hole 43 via the slits 49 near the manifold hole 43. In addition, the slits 49 near the manifold holes 41 and 46 of the frame 12 respectively connect the manifold holes 41 and 46 to the flow channel 31. As a result, the oxidizer gas flowing through the manifold hole 46 flows into the flow channel 31 via the slits 49 near the manifold hole 46, and then flows from the flow channel 31 into the manifold hole 41 via the slits 49 near the manifold hole 41.

[0014] Fig. 2 is a flowchart showing a method for manufacturing the fuel cell 100. Fig. 2 shows the step of joining the plate member 10 and one separator, which is one of the steps for manufacturing the fuel cell 100. The following describes an example in which the plate member 10 and the anode separator 20 are joined.

[0015] In step S10, adhesive 60 is applied to the first surface in a line shape having a predetermined width. Here, the first surface refers to the surface of the frame 12 facing the anode separator 20. When joining the plate member 10 and the cathode separator 30, the surface of the frame 12 facing the cathode separator 30 is also called the first surface. The adhesive 60 is made of, for example, a soft gel-like material. In this embodiment, the adhesive 60 is a known thermosetting adhesive. The width of the adhesive 60 applied to the first surface is determined by the operator. Step S10 is also called the first process.

[0016] 3 is a diagram showing a state in which adhesive 60 has been applied to first surface 16. Adhesive 60 is applied to first surface 16 so as to surround manifold holes 43 and 44 and power generation section 11. Adhesive 60 is also applied to first surface 16 so as to surround manifold holes 41, 42, 45, and 46, respectively. This makes it possible to prevent oxidant gas and coolant from leaking between plate member 10 and anode separator 20. The path along which adhesive 60 is applied is also called a seal line.

[0017] In step S20 of FIG. 2, hardened portions 61 having a higher hardness than the adhesive 60 are formed at the widthwise ends of the adhesive 60. In this embodiment, the hardened portions 61 are formed by heating and hardening the widthwise ends of the adhesive 60 using a laser, an ion beam, a heater, or the like. In this embodiment, the hardened portions 61 are formed at both widthwise ends of the entire adhesive 60 applied to the first surface 16. For example, in the adhesive 60 applied so as to surround the manifold hole 41 shown in FIG. 3, hardened portions 61 are formed on the inner and outer peripheries of the adhesive 60. FIG. 4 shows a state in which hardened portions 61 are formed at both widthwise ends of the adhesive 60. Note that the hardened portions 61 may be formed only in a portion of the adhesive 60 applied to the first surface 16, or may be formed only at one widthwise end of the adhesive 60. Step S20 is also referred to as a second step.

[0018] 2, the hardened portion 61 and the second surface are brought into contact. Here, the second surface refers to the surface of the anode separator 20 that faces the first surface 16 of the frame 12. When joining the plate member 10 and the cathode separator 30, the surface of the cathode separator 30 that faces the first surface of the frame 12 is called the second surface. The hardened portion 61 and the second surface are brought into contact by moving the plate member 10, which is suspended with the first surface 16 facing downward, relative to the anode separator 20, which is arranged with the second surface facing upward.

[0019] FIG. 5 is a schematic diagram showing how the plate member 10 and the anode separator 20 are joined together. FIG. 5 shows arrows representing the mutually orthogonal X, Y, and Z directions. The X and Y directions are parallel to the horizontal plane. The Z direction is parallel to the vertical direction. When specifying the direction, positive and negative signs are used in combination to indicate the direction, with "+" indicating the positive direction indicated by the arrow and "-" indicating the negative direction opposite to the direction indicated by the arrow.

[0020] As shown in FIG. 5 , the plate member 10 and the anode separator 20 are bonded together by a bonding apparatus 200 including a conveying unit 210 and a stage 220. The anode separator 20 is fixed on the stage 220 with the second surface 26 facing upward. The plate member 10 is suspended by the conveying unit 210 with the first surface 16 facing downward. Specifically, the plate member 10 is suspended by a holding unit 211 provided on the underside of the conveying unit 210, which holds the adhesive 60 applied to the surface opposite the first surface 16. The conveying unit 210 is movable in the horizontal and vertical directions. In this embodiment, the bonding apparatus 200 moves the conveying unit 210 relative to the fixed stage 220, thereby moving the plate member 10 and the anode separator 20 relative to each other. The bonding device 200 may be configured to move the stage 220 relative to the fixed transport unit 210, or may be configured to move the transport unit 210 in the horizontal direction and move the stage 220 in the vertical direction.

[0021] In step S30, the bonding device 200 moves the plate member 10 downward to bring the cured portion 61 into contact with the second surface 26. The adhesive 60 shown in FIG. 5 is applied linearly along the Y direction, with the cured portions 61 formed at the +X-direction end and the -X-direction end. As shown in FIG. 5, the plate member 10 suspended by the conveying unit 210 is bent by gravity so that its center protrudes downward. As the plate member 10 bends, the vertical height of the cured portion 61 formed at the inner end of the first surface 16 is lower than the vertical height of the cured portion 61 formed at the outer end. The inner end refers to the end closer to the center of the plate member 10 in the X direction, and the outer end refers to the end farther from the center of the plate member 10 in the X direction. As the plate member 10 moves downward, the cured portion 61 formed at the inner end comes into contact with the second surface 26. Step S30 is also referred to as the third step.

[0022] 2, the bonding device 200 performs positioning by moving the plate member 10 relative to the separator in a direction parallel to the second surface 26 with the hardened portion 61 in contact with the second surface 26. Specifically, the bonding device 200 performs positioning of the plate member 10 and the anode separator 20 by aligning the positions, in the horizontal plane, of the through-hole 212 that passes through the transport unit 210 in the vertical direction and the protrusion 221 that protrudes in the +Z direction from the upper surface of the stage 220. FIG. 5 shows how the positioning is performed by moving the plate member 10 in the +X direction. Step S40 is also referred to as a fourth process.

[0023] In step S50 of FIG. 2, the bonding device 200 bonds the plate member 10 and the anode separator 20 together by holding the plate member 10 until the entire adhesive 60 has hardened.

[0024] According to the first embodiment described above, when joining plate member 10 and one separator, hardened portions 61 are formed at the widthwise ends of adhesive 60 applied to first surface 16, and plate member 10, which is suspended with first surface 16 facing downward, is moved relative to the separator, which is arranged with second surface 26 facing upward, to bring hardened portion 61 into contact with second surface 26. With hardened portion 61 in contact with second surface 26, plate member 10 is moved relative to the separator in a direction parallel to second surface 26, thereby positioning plate member 10. In contrast, if hardened portions 61 are not formed at the widthwise ends of adhesive 60, moving plate member 10 relative to the separator in a direction parallel to second surface 26 with the end of adhesive 60 in contact with second surface 26 will cause the thickness of adhesive 60 to change partially because it is soft. In this embodiment, since hardened portions 61 are formed at the widthwise ends of the adhesive 60, even if the plate member 10 and the separator are moved as described above, the hardened portions 61 are less likely to deform than the adhesive 60, and therefore changes in the thickness of the adhesive 60 can be suppressed. Furthermore, since the thickness of the adhesive 60 can be suppressed from becoming thinner, a weakening of the compressive force required to bond the plate member 10 and the separator can be suppressed.

[0025] B. Other Embodiments: (B-1) In the above embodiment, the adhesive 60 is a known thermosetting adhesive. Alternatively, the adhesive 60 may be a known chemically curing adhesive. In this case, in step S20 of FIG. 2, an acid solution or an alkaline solution is applied to the widthwise end of the adhesive 60, and the adhesive is cured by a chemical reaction, thereby creating the cured portion 61. Alternatively, the adhesive 60 may be a known adhesive that hardens through degradation. In this case, in step S20 of FIG. 2, the widthwise end of the adhesive 60 is irradiated with ultraviolet light, ozone, or the like to promote degradation, thereby creating the cured portion 61.

[0026] (B-2) In the above embodiment, the hardened portion 61 is created by hardening the widthwise end portion of the adhesive 60 applied to the first surface 16. Alternatively, the hardened portion 61 may be created by adding a reinforcing material to the widthwise end portion of the adhesive 60 applied to the first surface 16. The reinforcing material may be, for example, another adhesive having a higher hardness than the adhesive 60, a resin material, a rubber material, or the like. In this case, in step S20 of FIG. 2 , the hardened portion 61 is created by applying or adhering the above-mentioned reinforcing material to the widthwise end portion of the adhesive 60. Alternatively, the hardened portion 61 may be created by embedding reinforcing material fibers in the widthwise end portion of the adhesive 60.

[0027] The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0028] 10...plate member, 11...power generation section, 12...frame, 13...opening, 16...first surface, 20...anode separator, 21...flow channel, 26...second surface, 30...cathode separator, 31...flow channel, 41, 42, 43, 44, 45, 46...manifold holes, 49...slit, 60...adhesive, 61...curing section, 100...fuel cell, 200...bonding device, 210...transport section, 211...holding section, 212...through hole, 220...stage, 221...protrusion

Claims

[Claim 1] A method for manufacturing a fuel cell, comprising joining a plate member having a membrane electrode assembly and a frame supporting the membrane electrode assembly, and one of a pair of separators sandwiching the plate member, the method comprising: a first step of applying an adhesive in a line shape having a predetermined width to a first surface of the frame, the first surface being a surface facing the separator; a second step of forming a hardened portion having a harderness higher than that of the adhesive at an end portion in a width direction of the adhesive; a third step of moving the plate member, which is suspended with the first surface facing downward, relative to the separator, which has a second surface facing opposite the first surface and is disposed with the second surface facing upward, to bring the hardened portion into contact with the second surface; and a fourth step of positioning the plate member relative to the separator in a direction parallel to the second surface while the hardened portion is in contact with the second surface. A method for manufacturing a fuel cell.

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