JP2019096389A - Method of manufacturing fuel battery cell - Google Patents

Abstract

To provide a method of manufacturing a fuel battery cell, preventing the elution of a radical scavenger (antioxidant) from a support frame and efficiently curing an adhesive so that adhesion (adhesive force) of the support frame can be ensured.SOLUTION: In a method of manufacturing a fuel battery cell, an adhesive later 12 is irradiated with ultraviolet rays while a support frame 11 is brought into close contact with a cooling plate 13 that suppresses a temperature rise of the support frame 11, and a membrane electrode assembly 4 is bonded to the support frame 11 via the adhesive layer 12 irradiated with ultraviolet rays.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method of manufacturing a fuel cell.

  In a fuel cell (sometimes referred to as a fuel cell stack), an electrolyte membrane sandwiched between an anode and a cathode is used as a cell (a single cell) (sometimes referred to as a fuel cell), and a plurality of the cells are separated via a separator. It is configured by overlapping (stacking).

  For example, a fuel cell of a polymer electrolyte fuel cell comprises an ion permeable electrolyte membrane, and an anode catalyst layer (electrode catalyst layer) and a cathode catalyst layer (electrode catalyst layer) sandwiching the electrolyte membrane. A membrane electrode assembly (MEA: Membrane Electrode Assembly) is provided. On both sides of the MEA, a gas diffusion layer (GDL: Gas Diffusion Layer) is formed to provide fuel gas or oxidant gas and to collect electricity generated by the electrochemical reaction. The membrane electrode assembly in which GDLs are disposed on both sides is referred to as MEGA (Membrane Electrode & Gas Diffusion Layer Assembly), and MEGA is sandwiched by a pair of separators. Here, the MEGA is a power generation unit of the fuel cell, and when there is no gas diffusion layer, the MEA is a power generation unit of the fuel cell.

  The MEGA as a power generation unit used for the fuel cell described above has, for example, a method of laminating GDL on both sides of MEA composed of an electrolyte membrane and an electrode catalyst layer, or an electrode catalyst layer and GDL on both sides of the electrolyte membrane. Although manufactured using the method of laminating | stacking the gas diffusion electrode comprised, MEGA of such a structure is easy to be thin and bent. Therefore, for example, for the purpose of protection of MEGA and reduction of manufacturing cost, MEGA with a support frame (hereinafter referred to as a frame MEGA) in which a support frame supporting the MEGA is arranged around the MEGA is known (for example, See Patent Documents 1 and 2 below). In this frame MEGA, the MEGA and the support frame are bonded using an adhesive.

  The supporting frame is usually composed of a resin frame made of a thermoplastic resin such as PP (polypropylene, polypropylene), phenol resin, epoxy resin, PE (polyethylene, polyethylene), PET (polyethylene terephthalate, polyethylene terephthalate), MEGA It is formed in a frame shape that locks onto the peripheral edge of the frame.

  Further, as the adhesive, there is no need to heat for curing in order to suppress the stress of the support frame and suppress the deformation of the support frame, and an ultraviolet curing adhesive that cures with ultraviolet light (UV) of a predetermined wavelength It has been proposed to use In this UV-curable adhesive, radicals are generated when exposed to ultraviolet light, and curing proceeds from the radicals to bond the MEGA and the support frame.

JP, 2015-215958, A JP, 2016-162652, A

  By the way, the support frame (resin frame) in the frame MEGA contains a radical scavenger as an antioxidant in order to improve the durability. Further, since the support frame also has a property of absorbing ultraviolet light, the temperature rises by ultraviolet irradiation, and the radical scavenger is eluted from the support frame, and the adhesive (adhesive having ultraviolet curing property) is eluted by the eluted radical scavenger. Curing of the agent) may be inhibited, and the adhesion (adhesive strength) of the support frame may be reduced.

  The present invention has been made in view of the above problems, and the object of the present invention is to prevent elution of a radical scavenger (antioxidant) from a support frame and to cure the adhesive efficiently to support the support. It is an object of the present invention to provide a method of manufacturing a fuel cell which can ensure the adhesion (adhesive force) of a frame.

  In order to solve the above problems, according to a method of manufacturing a fuel cell according to the present invention, a membrane electrode assembly in which electrode catalyst layers are formed on both sides of an electrolyte membrane and the membrane electrode assembly are disposed on both sides. What is claimed is: 1. A method of manufacturing a fuel cell comprising: a gas diffusion layer; and a support frame formed of a thermoplastic resin and supporting the membrane electrode assembly on the outer periphery of the membrane electrode assembly. Preparing a membrane electrode assembly in which a gas diffusion layer is disposed on one side surface and a gas diffusion layer is not disposed on the other side surface of the membrane electrode assembly; The step of forming an adhesive layer made of a radical polymerization type UV curable adhesive on the outer peripheral edge, and the adhesion while bringing a cooling plate in close contact with the support frame to suppress a temperature rise of the support frame Irradiating ultraviolet radiation to the layer, it is characterized in that through the adhesive layer with ultraviolet is irradiated and a step of bonding the said support frame and the membrane electrode assembly.

  According to the present invention, when performing the ultraviolet irradiation for curing the ultraviolet-curable adhesive layer, the temperature rise of the support frame is suppressed (inhibited) by the cooling plate in close contact with the support frame. Thus, the radical scavenger (antioxidant) can be prevented from eluting out, the adhesive can be cured efficiently, and the adhesiveness (adhesive force) of the support frame can be secured.

It is principal part sectional drawing of a fuel cell stack containing a fuel cell. It is a principal part expanded sectional view of a fuel cell stack containing a fuel cell. It is a flowchart which shows the outline of the manufacturing process of a fuel cell. It is a principal part expanded sectional view showing the outline of the manufacturing process of a fuel cell, (A) is a preparatory process, (B) is an adhesive bond layer formation process, (C) is a support frame bonding process, (D) is a press. A process and (E) are figures showing an adhesion process. It is a figure which shows the relationship between the temperature of a support frame, and the hardening degree of an adhesive bond layer. It is a figure which shows the temperature of the support frame by ultraviolet irradiation.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings. The following description exemplifies a case where the present invention is applied to a fuel cell mounted on a fuel cell vehicle or a fuel cell system including the same as an example, but the scope of application is not limited to such an example. .

[Configuration of Fuel Cell Stack Including Fuel Cells]
FIG. 1 is a cross-sectional view of the main part of a fuel cell stack (fuel cell) 10. As shown in FIG. 1, in the fuel cell stack 10, a plurality of cells (unit cells) 1 which are basic units are stacked. Each cell 1 is a polymer electrolyte fuel cell that generates an electromotive force by an electrochemical reaction of an oxidant gas (for example, air) and a fuel gas (for example, hydrogen). The cell 1 includes the MEGA 2 and a separator (fuel cell separator) 3 in contact with the MEGA 2 so as to partition the MEGA 2. In the present embodiment, the MEGA 2 is sandwiched by the pair of separators 3, 3.

  MEGA 2 is one in which a membrane electrode assembly (MEA) 4 and gas diffusion layers 7 disposed on both sides thereof are integrated. The membrane electrode assembly 4 includes an electrolyte membrane 5 and a pair of electrode catalyst layers 6 and 6 joined so as to sandwich the electrolyte membrane 5. The electrolyte membrane 5 is formed of a proton conductive ion exchange membrane formed of a solid polymer material, and the electrode catalyst layer 6 is formed of, for example, a porous carbon material supporting a catalyst such as platinum. The electrode catalyst layer 6 disposed on one side of the electrolyte membrane 5 is an anode, and the electrode catalyst layer 6 on the other side is a cathode. The gas diffusion layer 7 is formed of a conductive member having gas permeability such as a carbon porous body such as carbon paper or carbon cloth, or a metal porous body such as a metal mesh or a foam metal.

  In the present embodiment, the MEGA 2 is a power generation unit of the fuel cell 10, and the separator 3 is in contact with the gas diffusion layer 7 of the MEGA 2. When the gas diffusion layer 7 is omitted, the membrane electrode assembly 4 is a power generation unit, and in this case, the separator 3 is in contact with the membrane electrode assembly 4. Therefore, the power generation unit of the fuel cell 10 includes the membrane electrode assembly 4 and is in contact with the separator 3.

  The separator 3 is a plate-like member whose base material is a metal excellent in conductivity, gas impermeability, etc. (for example, a metal such as SUS, titanium, aluminum, copper, nickel, etc.), one side of which is MEGA 2 It is in contact with the gas diffusion layer 7, and the other surface side is in contact with the other surface side of the other adjacent separator 3.

  In the present embodiment, each separator 3 is formed in a wave shape or a concavo-convex shape (in cross section). The shape of the separator 3 is an isosceles trapezoidal wave, and the top of the wave is almost flat, and both ends of the top are angular at equal angles. That is, the respective separators 3 have substantially the same shape as viewed from the front side or viewed from the back side. The top of the separator 3 is in surface contact with one gas diffusion layer 7 of the MEGA 2, and the top of the separator 3 is in surface contact with the other gas diffusion layer 7 of the MEGA 2.

  The gas flow path 21 defined between the gas diffusion layer 7 on one electrode catalyst layer (ie anode) 6 side and the separator 3 is a flow passage through which the fuel gas flows, and the other electrode catalyst layer (ie The gas flow path 22 defined between the gas diffusion layer 7 on the cathode 6 side and the separator 3 is a flow path through which the oxidant gas flows. When the fuel gas is supplied to one of the opposing gas flow paths 21 via the cell 1 and the oxidant gas is supplied to the gas flow path 22, an electrochemical reaction occurs in the cell 1 to generate an electromotive force.

  Further, one cell 1 and another cell 1 adjacent thereto are disposed such that the electrode catalyst layer 6 serving as the anode and the electrode catalyst layer 6 serving as the cathode face each other. Also, the top of the back side of the separator 3 disposed along the electrode catalyst layer 6 serving as the anode of one cell 1 and the separator 3 disposed along the electrode catalyst layer 6 serving as the cathode of another cell 1 The top of the back side is in surface contact. Water as a refrigerant for cooling the cells 1 flows in a space 23 defined between the separators 3 and 3 in surface contact between two adjacent cells 1.

  Further, as shown in FIG. 2, in each cell 1 constituting the fuel cell 10 described above, a support frame 11 for supporting the MEGA 2 is disposed on the outer periphery of the MEGA 2, and the MEGA 2 and the support frame 11 are made of resin. It adheres through the adhesive layer 12 comprised with an adhesive agent (frame MEGA9).

  The adhesive constituting the adhesive layer 12 is an ultraviolet (UV) curable adhesive using a radical polymerizable resin, and has a property of being cured by ultraviolet irradiation of a predetermined wavelength. Examples of the UV-curable adhesive using a radically polymerizable resin include an adhesive of a UV-curable polyisobutylene resin, an adhesive of a UV-curable epoxy resin, and an adhesive of a UV-curable acrylic resin. The application method of the adhesive for the adhesive layer 12 includes, for example, a screen printing method, a method of applying using a dispenser, and the like, and by these methods, the adhesive layer 12 (adhesive) is MEGA 2 The membrane electrode assembly 4 is formed on the outer peripheral edge portion thereof.

  The support frame 11 is made of, for example, a resin frame made of a thermoplastic resin such as PP (polypropylene, polypropylene), phenol resin, epoxy resin, PE (polyethylene, polyethylene), PET (polyethylene terephthalate, polyethylene terephthalate), MEGA 2 It is formed in a frame shape that locks onto the peripheral edge of the frame. The support frame 11 has a gap with the outer peripheral portion of the gas diffusion layer 7 (the cathode gas diffusion layer 7 in the illustrated example) disposed on the membrane electrode assembly 4 (in other words, the gas diffusion layer 7 And spaced apart) on the adhesive layer 12).

  The adhesive layer 12 is irradiated with ultraviolet light of a predetermined wavelength, and the adhesive layer 12 irradiated with the ultraviolet light is cured, whereby the MEGA 2 and the support frame 11 are bonded via the adhesive layer 12. At this time, in the present embodiment, the MEGA 2 and the support frame 11 are bonded while suppressing the temperature rise of the support frame 11 due to the ultraviolet irradiation using a cooling plate made of quartz glass or the like (described in detail later) ).

  Further, (both surfaces of) the support frame 11 are vinyl acetate resin, polyvinyl alcohol resin, ethylene vinyl acetate resin, vinyl chloride resin, acrylic resin, polyamide resin, cellulose resin, polyvinyl pyrrolidone resin, An adhesive layer (not shown) composed of an adhesive made of a thermoplastic resin such as a polystyrene resin, a cyanoacrylate resin, or a polyvinyl acetal resin is formed. The support frame 11 is heated to melt the adhesive layer, and the support frame 11 is cooled to solidify the adhesive layer, whereby the support frame 11 and the both separators 3, 3 and the like holding the MEGA 2 adhere to each other. Being fixed.

[Fuel cell manufacturing process]
Next, a method of manufacturing the cell (fuel cell) 1 using the above-mentioned frame MEGA 9 will be described. FIG. 3 is a flow diagram schematically showing a manufacturing process of the fuel cell.

  In manufacturing the cell 1, as shown in FIG. 3, first, the gas diffusion layer 7 (the anode gas diffusion layer 7 in the illustrated example) is disposed on one side surface (lower surface) 4a, and the other side surface (upper surface) 4b A membrane / electrode assembly 4 is prepared on which the gas diffusion layer (in the illustrated example, the cathode gas diffusion layer 7) is not disposed (that is, the other side surface 4b is exposed) (S11: preparation step) (FIG. 4 (A) )reference). The anode gas diffusion layer 7 and the membrane electrode assembly 4 are bonded in advance by, for example, a heating press process.

  Next, on the outer peripheral edge of the other side surface 4b of the membrane electrode assembly 4, the above-mentioned radical polymerization type UV curable adhesive is applied to form the adhesive layer 12 (S12: adhesive layer formation Step) (see FIG. 4 (B)).

  Next, the support frame 11 is disposed on and bonded to the adhesive layer 12 (S13: support frame bonding step) (see FIG. 4C), and the membrane electrode assembly 4 is processed by the press 20. The support frame 11 is pressed at a predetermined pressure to degas the adhesive layer 12 (S14: pressing step) (see FIG. 4D).

  Next, for example, ultraviolet rays of a predetermined wavelength are irradiated toward the adhesive layer 12 from the upper side (that is, as the cooling plate 13 and the support frame 11 are transmitted). Thereby, the adhesive layer 12 irradiated with ultraviolet rays is cured, and the membrane electrode assembly 4 and the support frame 11 are bonded (S15: bonding step) (see FIG. 4E). In the present embodiment, the cooling plate 13 made of, for example, quartz glass is brought into close contact with the support frame 11 (for example, the surface opposite to the adhesive layer 12 side) in the ultraviolet irradiation (detailedly pressed) Thus, the temperature rise of the support frame 11 due to the ultraviolet irradiation is suppressed.

  Here, although depending on the materials of the support frame 11 and the adhesive layer 12, etc., for example, the support frame 11 can maintain its shape at about 135 ° C. or less, and the curing degree of the adhesive layer 12 at about 70 ° C. or less It has been confirmed that 85% or more can be secured (see FIG. 5).

In the bonding step (S15) described above, the irradiation conditions of ultraviolet rays (for example, irradiation intensity of ultraviolet rays, irradiation time, etc.) are appropriately selected depending on the material of the adhesive layer 12, etc. For example, irradiation intensity 1300 mW / cm ² In the conventional method in which the cooling plate 13 is not used, the temperature of the support frame 11 rises to about 100 ° C., but when the cooling plate 13 is used, the temperature (rise) of the support frame 11 is 30%. It has been confirmed that the temperature can be reduced to about ° C. In addition, it is confirmed that the temperature (rise) of the support frame 11 can be suppressed to about 30 ° C. even when the irradiation intensity is controlled without using the cooling plate 13 and the irradiation intensity is 700 mW / cm ² for 2 seconds. (See Figure 6).

  Therefore, by using the cooling plate 13 in the aforementioned bonding step (S15), the elution of the radical scavenger (antioxidant) from the support frame 11 is suppressed, and the curing degree of the adhesive layer 12 is secured. Can.

  After the adhesion step (S15) described above, the gas diffusion layer (cathode gas diffusion layer 7) is disposed and bonded onto the other side surface (upper surface) 4b of the membrane electrode assembly 4 (S16: GDL bonding step). The cathode gas diffusion layer 7 and the membrane electrode assembly 4 are joined, for example, by a heating press process or the like.

  Thereby, MEGA 2 (frame MEGA 9) with the support frame 11 is produced.

  Next, on both sides of the membrane electrode assembly 4 in which the gas diffusion layers 7, 7 are arranged on both sides and the support frame 11 (frame MEGA 9), the separators 3 and 3 functioning as current collectors are arranged. A sealing member (not shown) for insulating the separators 3 and 3 and sealing the inside of the cell 1 is disposed, and they are sandwiched between the separators 3 and 3 (S17: separator holding step).

  Then, while pressing the separators 3, 3 and the like, the support frame 11 is heated to melt the adhesive layers on both sides of the support frame 11 (S18: heating and pressing process), and the support frame 11 is cooled to perform the bonding. The layer is solidified (S19: cooling press step).

  Thereby, the support frame 11 and the both separators 3, 3 are adhered and fixed, and the membrane electrode assembly 4, the gas diffusion layers 7, 7, the support frame 11, the separators 3, 3 etc. The assembly of the cell (fuel cell) 1 using the MEGA 9 is completed.

  As described above, in the present embodiment, when performing the ultraviolet irradiation for curing the ultraviolet curable adhesive layer 12, the temperature rise of the support frame 11 is caused by the cooling plate 13 in close contact with the support frame 11. Since it is inhibited (inhibited), elution of the radical scavenger (antioxidant) from the support frame 11 can be prevented, the adhesive can be cured efficiently, and the adhesiveness (adhesion force of the support frame 11) ) Can be secured.

  As mentioned above, although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and there are design changes and the like within the scope of the present invention. Also, they are included in the present invention.

DESCRIPTION OF SYMBOLS 1 ... fuel cell (cell), 2 ... MEGA, 3 ... separator, 4 ... membrane electrode assembly (MEA), 4 a ... one side of membrane electrode assembly, 4 ... other side of membrane electrode assembly, 5 ... electrolyte Membrane, 6: Electrode catalyst layer, 7: Gas diffusion layer, 9: Frame MEGA, 10: Fuel cell stack (fuel cell), 11: Support frame, 12: Adhesive layer, 13: Cooling plate, 21, 22: Gas Flow path, 23 ... Space where water flows

Claims (1)

A membrane electrode assembly in which electrode catalyst layers are respectively formed on both sides of an electrolyte membrane,
Gas diffusion layers respectively disposed on both sides of the membrane electrode assembly;
What is claimed is: 1. A method of manufacturing a fuel cell comprising: a support frame formed of a thermoplastic resin and supporting the membrane electrode assembly on the outer periphery of the membrane electrode assembly,
Preparing the membrane electrode assembly in which the gas diffusion layer is disposed on one side surface of the membrane electrode assembly and the gas diffusion layer is not disposed on the other side surface of the membrane electrode assembly;
Forming an adhesive layer made of a radical polymerization type UV curable adhesive on the outer peripheral edge of the other side surface of the membrane electrode assembly;
The adhesive layer is irradiated with ultraviolet light while the cooling plate for suppressing temperature rise of the support frame is in close contact with the support frame, and the membrane electrode assembly and the support are supported via the adhesive layer irradiated with ultraviolet light. And a step of bonding with a frame.

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