JP2017068908A - Manufacturing method for resin frame-attached electrolyte membrane-electrode structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form, by a simple step, an adhesive layer superior in bonding strength, which can suppress the air entrainment in an adhesive bonding portion with reliability.SOLUTION: A method for manufacturing a resin frame-attached electrolyte membrane-electrode structure 10 comprises the steps of: providing a hot melt sheet 26a in a junction portion of a solid polymer electrolyte film 18 and a resin frame member 24, provided that the hot melt sheet 26a consists of a sheet-like hot melt with a plurality of through-holes 56 formed therein so as to extend through the sheet in a thickness direction thereof; and performing a heat treatment on the junction portion where the hot melt sheet 26a is provided with a load applied to the junction portion.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an electrolyte membrane / electrode with a resin frame for a fuel cell, comprising: a step MEA having a solid polymer electrolyte membrane sandwiched between a first electrode and a second electrode; and a resin frame member joined to the outer periphery of the step MEA. The present invention relates to a method for manufacturing a structure.

  In general, a polymer electrolyte fuel cell employs a polymer electrolyte membrane made of a polymer ion exchange membrane. The fuel cell includes an electrolyte membrane / electrode structure (MEA) in which an anode electrode is disposed on one surface of a solid polymer electrolyte membrane and a cathode electrode is disposed on the other surface of the solid polymer electrolyte membrane. Yes. The anode electrode and the cathode electrode each have a catalyst layer (electrode catalyst layer) and a gas diffusion layer (porous carbon).

  The electrolyte membrane / electrode structure is sandwiched between separators (bipolar plates) to form a power generation cell (unit fuel cell). This power generation cell is used as, for example, an in-vehicle fuel cell stack by stacking a predetermined number.

  In the electrolyte membrane / electrode structure, one gas diffusion layer is set to a plane size smaller than that of the solid polymer electrolyte membrane, and the other gas diffusion layer is set to substantially the same plane size as the solid polymer electrolyte membrane. The so-called step MEA may be configured. At that time, in order to reduce the amount of the relatively expensive solid polymer electrolyte membrane used and to protect the solid polymer electrolyte membrane having a thin film shape and low strength, an MEA with a resin frame incorporating a resin frame member is adopted. Has been.

  As an MEA with a resin frame, for example, an electrolyte membrane / electrode structure with a resin frame for a fuel cell disclosed in Patent Document 1 is known. In this electrolyte membrane / electrode structure with a resin frame for a fuel cell, the inner peripheral edge of the resin frame member and the outer peripheral edge of the solid polymer electrolyte membrane are adhesive layers such as ester-based or urethane-based hot It is fixed with a melt adhesive.

JP2013-98155A

  By the way, when a hot melt sheet is used as an adhesive for joining the MEA and the resin frame member, between the hot melt sheet and the resin frame member or between the hot melt sheet and the solid polymer electrolyte membrane. There is a case where air enters in between (so-called air biting). For this reason, there is a problem that the adhesive strength between the solid polymer electrolyte membrane and the resin frame member is lowered and the gas barrier property is deteriorated.

  The present invention solves this type of problem, and is a resin capable of reliably suppressing air biting at an adhesion site and forming an adhesive layer with excellent adhesion strength by a simple process. It aims at providing the manufacturing method of the electrolyte membrane and electrode structure with a frame.

  The present invention relates to a method of manufacturing an electrolyte membrane / electrode structure with a resin frame for a fuel cell having a step MEA and a resin frame member. In the step MEA, a first electrode is provided on one surface of the solid polymer electrolyte membrane, a second electrode is provided on the other surface of the solid polymer electrolyte membrane, and a plane of the first electrode is provided. The dimension is set to be larger than the planar dimension of the second electrode. The resin frame member is joined to the outer peripheral surface of the solid polymer electrolyte membrane exposed to the outside of the second electrode by hot melt.

  In this manufacturing method, the hot melt is a sheet-like hot melt in which a plurality of through-holes penetrating in the thickness direction are formed, and the sheet-like hot melt is formed at a joint portion between the solid polymer electrolyte membrane and the resin frame member. A step of disposing the melt. This manufacturing method further includes a step of heating the bonding site where the sheet-like hot melt is disposed and applying a load.

  In this manufacturing method, the through hole preferably has a diameter in the range of 20 μm to 500 μm.

  According to the present invention, the sheet-like hot melt is formed with a plurality of through holes penetrating in the thickness direction. For this reason, when air biting occurs in the sheet-like hot melt at the joining portion, the air is discharged to the outside of the joining portion through the through hole. Therefore, the air biting can be reliably suppressed by a simple process, and an adhesive layer excellent in adhesive strength can be reliably formed.

It is a principal part disassembled perspective explanatory view of a polymer electrolyte power generation cell in which an electrolyte membrane / electrode structure with a resin frame to which a manufacturing method according to an embodiment of the present invention is applied is incorporated. It is II-II sectional view explanatory drawing in FIG. 1 of the said electric power generation cell. In the said manufacturing method, it is explanatory drawing at the time of forming CCM which comprises the said electrolyte membrane and electrode structure with a resin frame. In the said manufacturing method, it is front explanatory drawing of a hot-melt sheet. In the said manufacturing method, it is explanatory drawing at the time of joining a resin frame member to level | step difference MEA. It is explanatory drawing of the joining operation | work of the said level | step difference MEA and the said resin frame member in the said manufacturing method. It is explanatory drawing when air biting generate | occur | produces in the said hot-melt sheet in the said manufacturing method.

  As shown in FIGS. 1 and 2, an electrolyte membrane / electrode structure 10 with a resin frame to which the manufacturing method according to the embodiment of the present invention is applied is a horizontally long (or vertically long) rectangular polymer electrolyte power generation cell. (Fuel cell) 12 is incorporated. The plurality of power generation cells 12 are stacked in, for example, an arrow A direction (horizontal direction) or an arrow C direction (gravity direction) to form a fuel cell stack. The fuel cell stack is mounted on, for example, a fuel cell electric vehicle (not shown) as an in-vehicle fuel cell stack.

  The power generation cell 12 sandwiches the electrolyte membrane / electrode structure 10 with a resin frame between the first separator 14 and the second separator 16. The first separator 14 and the second separator 16 have a horizontally long (or vertically long) rectangular shape. The first separator 14 and the second separator 16 are made of, for example, a steel plate, a stainless steel plate, an aluminum plate, a plating-treated steel plate, a metal plate whose surface is subjected to anticorrosion treatment, a carbon member, or the like.

  The electrolyte membrane / electrode structure 10 with a rectangular resin frame includes a step MEA 10a. As shown in FIG. 2, the step MEA 10a includes, for example, a solid polymer electrolyte membrane 18 that is a thin film of perfluorosulfonic acid containing moisture, and an anode electrode (first electrode) that sandwiches the solid polymer electrolyte membrane 18 20 and a cathode electrode (second electrode) 22. The solid polymer electrolyte membrane 18 is a cation exchange membrane, and an HC (hydrocarbon) electrolyte may be used in addition to the fluorine electrolyte.

  The cathode electrode 22 has a smaller planar dimension (outer dimension) than the solid polymer electrolyte membrane 18 and the anode electrode 20, and the solid polymer electrolyte membrane 18 and the anode electrode 20 have the same planar dimension. Instead of the above configuration, the anode electrode 20 may be configured to have a smaller planar dimension than the solid polymer electrolyte membrane 18 and the cathode electrode 22. At that time, the anode electrode 20 becomes the second electrode, and the cathode electrode 22 becomes the first electrode.

  As shown in FIG. 2, the anode electrode 20 includes a first electrode catalyst layer 20a bonded to one surface 18a of the solid polymer electrolyte membrane 18, and a first gas diffusion layer stacked on the first electrode catalyst layer 20a. Layer 20b. The first electrode catalyst layer 20a and the first gas diffusion layer 20b have the same planar dimensions (outer dimensions) and are set to the same (or less than the same) planar dimensions as the solid polymer electrolyte membrane 18. The first electrode catalyst layer 20a may be set to have a smaller planar dimension (or a larger planar dimension) than the first gas diffusion layer 20b.

  The cathode electrode 22 includes a second electrode catalyst layer 22a bonded to the surface 18b of the solid polymer electrolyte membrane 18, and a second gas diffusion layer 22b stacked on the second electrode catalyst layer 22a. The second electrode catalyst layer 22 a and the second gas diffusion layer 22 b have the same planar dimension and are set to a planar dimension smaller than the planar dimension of the solid polymer electrolyte membrane 18. An exposed surface 18be exposed to the outside of the cathode electrode 22 is provided on the outer peripheral edge of the solid polymer electrolyte membrane 18 on the surface 18b side.

  The second electrode catalyst layer 22a and the second gas diffusion layer 22b are set to have the same planar dimension, but the planar dimension of the second electrode catalyst layer 22a is the plane of the second gas diffusion layer 22b. It may have a dimension (or a dimension that is smaller) than the dimension.

  The first electrode catalyst layer 20a is formed by, for example, uniformly applying porous carbon particles having a platinum alloy supported on the surface thereof to the surface of the first gas diffusion layer 20b. The second electrode catalyst layer 22a is formed by, for example, uniformly applying porous carbon particles having a platinum alloy supported on the surface thereof to the surface of the second gas diffusion layer 22b.

  The first gas diffusion layer 20b is formed by a porous and conductive microporous layer 20b (m) and a carbon layer 20b (c) such as carbon paper or carbon cloth. The second gas diffusion layer 22b is formed by a porous and conductive microporous layer 22b (m) and a carbon layer 22b (c) such as carbon paper or carbon cloth. The planar dimension of the second gas diffusion layer 22b is set smaller than the planar dimension of the first gas diffusion layer 20b.

  The first electrode catalyst layer 20 a and the second electrode catalyst layer 22 a are formed on both surfaces of the solid polymer electrolyte membrane 18. Note that the microporous layers 20b (m) and 22b (m) may be provided as necessary, and may be unnecessary.

  The electrolyte membrane / electrode structure 10 with a resin frame includes a film-like resin frame member (resin molded body or resin film) 24 bonded to the exposed surface 18be of the solid polymer electrolyte membrane 18.

  The resin frame member 24 includes, for example, PPS (polyphenylene sulfide), PPA (polyphthalamide), PEN (polyethylene naphthalate), PES (polyethersulfone), LCP (liquid crystal polymer), PVDF (polyvinylidene fluoride), Silicone resin, fluororesin, m-PPE (modified polyphenylene ether resin), PET (polyethylene terephthalate), PBT (polybutylene terephthalate), modified polyolefin, or the like.

  The resin frame member 24 has a flat plate shape, and is provided with an adhesive surface 24 a that is bonded to the exposed surface 18 be of the solid polymer electrolyte membrane 18. Between the exposed surface 18be of the solid polymer electrolyte membrane 18 and the adhesive surface 24a of the resin frame member 24, an adhesive layer 26 made of a hot melt sheet (sheet-like hot melt) 26a is provided. The hot melt sheet 26a is, for example, a sheet-like solid adhesive that contains an epoxy group.

  As shown in FIG. 1, one end edge portion of the power generation cell 12 in the arrow B direction (horizontal direction in FIG. 1) communicates with each other in the arrow A direction that is the stacking direction, and the oxidant gas inlet communication hole 30 a. A cooling medium inlet communication hole 32a and a fuel gas outlet communication hole 34b are provided. The oxidant gas inlet communication hole 30a supplies an oxidant gas, for example, an oxygen-containing gas, while the cooling medium inlet communication hole 32a supplies a cooling medium. The fuel gas outlet communication hole 34b discharges fuel gas, for example, hydrogen-containing gas. The oxidant gas inlet communication hole 30a, the cooling medium inlet communication hole 32a, and the fuel gas outlet communication hole 34b are arranged in the direction of arrow C (vertical direction).

  The other end edge of the power generation cell 12 in the direction of arrow B communicates with each other in the direction of arrow A, the fuel gas inlet communication hole 34a for supplying fuel gas, the cooling medium outlet communication hole 32b for discharging the cooling medium, and the oxidation An oxidant gas outlet communication hole 30b for discharging the oxidant gas is provided. The fuel gas inlet communication hole 34a, the cooling medium outlet communication hole 32b, and the oxidant gas outlet communication hole 30b are arranged in the direction of arrow C.

  The resin frame member 24 includes an oxidant gas inlet communication hole 30a, a cooling medium inlet communication hole 32a, a fuel gas outlet communication hole 34b, a fuel gas inlet communication hole 34a, a cooling medium outlet communication hole 32b, and an oxidant gas outlet communication hole 30b. Is not formed.

  The surface 16a of the second separator 16 facing the electrolyte membrane / electrode structure 10 with a resin frame communicates with the oxidant gas inlet communication hole 30a and the oxidant gas outlet communication hole 30b and extends in the arrow B direction. An oxidant gas flow path 36 is provided.

  The surface 14a of the first separator 14 facing the electrolyte membrane / electrode structure 10 with a resin frame communicates with the fuel gas inlet communication hole 34a and the fuel gas outlet communication hole 34b and extends in the direction of arrow B. A fuel gas flow path 38 is formed. Between the surface 14b of the 1st separator 14 and the surface 16b of the 2nd separator 16 which adjoin each other, it communicates with the cooling-medium inlet communication hole 32a and the cooling-medium outlet communication hole 32b, and is extended in the arrow B direction. A cooling medium flow path 40 is formed.

  As shown in FIGS. 1 and 2, the first seal member 42 is integrated with the surfaces 14 a and 14 b of the first separator 14 around the outer peripheral end of the first separator 14. The second seal member 44 is integrated with the surfaces 16 a and 16 b of the second separator 16 around the outer peripheral end portion of the second separator 16.

  As shown in FIG. 2, the first seal member 42 includes a first convex seal 42 a that contacts the resin frame member 24 constituting the electrolyte membrane / electrode structure 10 with a resin frame, and a second seal of the second separator 16. And a second convex seal 42b in contact with the member 44. The second seal member 44 constitutes a flat seal in which the surface that contacts the second convex seal 42b extends in a flat shape along the separator surface. Instead of the second convex seal 42b, the second seal member 44 may be provided with a convex seal (not shown).

  For the first seal member 42 and the second seal member 44, for example, EPDM, NBR, fluororubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene or acrylic rubber or the like, cushion material Alternatively, an elastic seal member such as a packing material is used.

  Next, a manufacturing method according to an embodiment of the present invention for manufacturing an electrolyte membrane / electrode structure 10 with a resin frame will be described below.

  First, while the step MEA 10a is manufactured, the resin frame member 24 is prepared by a member injection-molded using a mold (not shown) or a member obtained by cutting a film into a frame shape with a Thomson blade. In order to produce the step MEA 10a, first, a slurry made of a mixture of carbon black and PTFE (polytetrafluoroethylene) particles is applied to the flat surface of the carbon layer 20b (c) made of carbon paper, and dried. A microporous layer 20b (m), which is a formation, is formed.

  The first gas diffusion layer 20b is formed by bonding the carbon layer 20b (c) to the microporous layer 20b (m). Similarly, the microporous layer 22b (m) is formed, and the carbon layer 22b (c) is bonded to the microporous layer 22b (m), thereby forming the second gas diffusion layer 22b.

  On the other hand, after adding a solvent to the electrode catalyst, for example, a solution of a perfluoroalkylenesulfonic acid polymer compound is added as an ion conductive polymer binder solution. Then, an anode electrode ink and a cathode electrode ink are created by adding a solvent until a predetermined ink clay is obtained.

  Therefore, as shown in FIG. 3, the anode electrode ink is applied to the PET film 50a by screen printing and dried by heating, whereby the anode electrode sheet 52 provided with the first electrode catalyst layer 20a is formed. The first electrode catalyst layer 20 a is set to have the same planar dimensions as the solid polymer electrolyte membrane 18.

  Similarly, the cathode electrode ink is applied to the PET film 50b by screen printing and dried by heating, whereby the cathode electrode sheet 54 provided with the second electrode catalyst layer 22a is formed. The second electrode catalyst layer 22 a is set to have a smaller planar dimension than the solid polymer electrolyte membrane 18.

  Next, hot pressing is performed in a state where the solid polymer electrolyte membrane 18 is sandwiched between the anode electrode sheet 52 and the cathode electrode sheet 54. Then, the PET films 50a and 50b are peeled to form a joined body (CCM) (catalyst coated membrane). Further, the first gas diffusion layer 20b and the second gas diffusion layer 22b sandwich the CCM between the microporous layers 20b (m) and 22b (m) and are integrated by hot pressing to produce the step MEA 10a. (See FIG. 2).

  A long hot melt web is prepared and cut with a Thomson blade to process the frame-shaped hot melt sheet 26a. As shown in FIG. 4, the hot melt sheet 26a has a width dimension t set within a range of 1 mm to 5 mm, and the hot melt sheet 26a has a plurality of through holes 56 formed by laser light irradiation or press molding. Is formed (see FIGS. 4 and 5).

  As shown in FIG. 4, the through holes 56 have a diameter in the range of 20 μm to 500 μm, and the through holes 56 are separated from each other by a dimension S1 along the arrow B direction and a dimension S2 along the arrow C direction. To do. The through holes 56 are arranged offset from each other in the width direction. The dimensions S1 and S2 are set within a range of 2 mm to 10 mm, for example. In the width dimension t, when the through holes 56 are arranged in a line, the through hole 56 is arranged at the center position of the width dimension t. When the through holes 56 are arranged in two rows, the through holes 56 are arranged at positions 1/3 and 2/3 of the width dimension t. When the through-holes 56 are arranged in three rows, the through-holes 56 are arranged at positions 1/4, 2/4, and 3/4 of the width dimension t.

  Next, as shown in FIG. 5, the hot melt sheet 26 a is disposed on the exposed surface 18 be of the solid polymer electrolyte membrane 18. The hot melt sheet 26 a may be disposed on the adhesive surface 24 a of the resin frame member 24.

  Further, as shown in FIG. 6, the servo press machine 60 has a bonding portion between the exposed surface 18be of the solid polymer electrolyte membrane 18 and the adhesive surface 24a of the resin frame member 24 with the hot melt sheet 26a interposed. Is heated and pressurized. The servo press machine 60 includes a fixed base 62 and a movable base 64, and the movable base 64 can be moved forward and backward with respect to the fixed base 62 by a piston 66.

  Therefore, when the fixed base 62 and the movable base 64 are heated to a predetermined temperature, for example, 160 ° C., the joint portion is moved by the fixed base 62 and the movable base 64 to an initial load of, for example, 0.01 MPa. Hold with (pressure). And until the temperature of the hot melt sheet 26a reaches 160 ° C., an initial load is applied to the joining portions for a predetermined interval.

  After a predetermined interval, for example, 10 seconds elapses after the initial load is applied, the bonding load (pressure) applied to the bonding portion is increased to, for example, 0.5 MPa, and the bonding is performed for a predetermined time. A load is applied. The bonding load is set in the range of 0.1 MPa to 2 MPa. For this reason, the step MEA 10a and the resin frame member 24 are joined by the adhesive layer 26, and the electrolyte membrane / electrode structure 10 with a resin frame is manufactured.

  By the way, since the hot melt sheet 26a is easily bent, for example, as shown in FIG. 7, the hot melt sheet 26a is arranged in a deformed state on the solid polymer electrolyte membrane 18 (or the resin frame member 24). There is. For this reason, a space 68 is formed between the hot melt sheet 26 a and the solid polymer electrolyte membrane 18, and there is a possibility that air biting by the space 68 occurs.

  In this case, in the present embodiment, the hot melt sheet 26a is formed with a plurality of through holes 56 penetrating in the thickness direction. Accordingly, the air in the space 68 is discharged to the outside of the hot melt sheet 26 a through the through hole 56.

  Further, the through hole 56 is closed when the hot melt sheet 26 a is heated and pressurized by the servo press 60, and the through hole 56 does not remain in the adhesive layer 26. Thereby, it is possible to surely suppress the air biting by a simple process, and to obtain an effect that the adhesive layer 26 excellent in adhesive strength and gas barrier property can be surely formed.

  Furthermore, the through-hole 56 has a diameter set in a range of 20 μm to 500 μm. If the diameter of the through hole 56 is less than 20 μm, it is difficult for air to escape, and there is a possibility that the air biting cannot be reliably eliminated. On the other hand, when the diameter of the through-hole 56 exceeds 500 μm, the through-hole 56 may not be blocked during bonding, and the adhesive strength may be reduced.

  The width dimension t of the hot melt sheet 26a is set within a range of 1 mm to 5 mm. If the width dimension t is less than 1 mm, insufficient adhesive force is caused. On the other hand, if the width dimension t exceeds 5 mm, the entire power generation cell 12 is unnecessarily large.

  Next, operation | movement of the electric power generation cell 12 comprised in this way is demonstrated below.

  First, as shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 30a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 34a. Supplied. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 32a.

  Therefore, the oxidant gas is introduced from the oxidant gas inlet communication hole 30a into the oxidant gas flow path 36 of the second separator 16, moves in the direction of arrow B, and is supplied to the cathode electrode 22 of the step MEA 10a. On the other hand, the fuel gas is introduced into the fuel gas flow path 38 of the first separator 14 from the fuel gas inlet communication hole 34a. The fuel gas moves in the direction of arrow B along the fuel gas flow path 38 and is supplied to the anode electrode 20 of the step MEA 10a.

  Therefore, in each step MEA 10a, the oxidant gas supplied to the cathode electrode 22 and the fuel gas supplied to the anode electrode 20 are electrochemically reacted in the second electrode catalyst layer 22a and the first electrode catalyst layer 20a. It is consumed and power is generated.

  Next, the oxidant gas consumed by being supplied to the cathode electrode 22 is discharged in the direction of arrow A along the oxidant gas outlet communication hole 30b. Similarly, the fuel gas consumed by being supplied to the anode electrode 20 is discharged in the direction of arrow A along the fuel gas outlet communication hole 34b.

  The cooling medium supplied to the cooling medium inlet communication hole 32a is introduced into the cooling medium flow path 40 between the first separator 14 and the second separator 16, and then flows in the direction of arrow B. The cooling medium is discharged from the cooling medium outlet communication hole 32b after cooling the step MEA 10a.

10 ... Electrolyte membrane / electrode structure with resin frame 10a ... Step MEA
DESCRIPTION OF SYMBOLS 12 ... Power generation cell 14, 16 ... Separator 18 ... Solid polymer electrolyte membrane 18be ... Exposed surface 20 ... Anode electrode 20a, 22a ... Electrode catalyst layer 20b, 22b ... Gas diffusion layer 22 ... Cathode electrode 24 ... Resin frame member 24a ... Adhesion Surface 26a ... Hot melt sheet 30a ... Oxidant gas inlet communication hole 30b ... Oxidant gas outlet communication hole 32a ... Cooling medium inlet communication hole 32b ... Cooling medium outlet communication hole 34a ... Fuel gas inlet communication hole 34b ... Fuel gas outlet communication hole 36 ... Oxidant gas passage 38 ... Fuel gas passage 40 ... Cooling medium passage 42, 44 ... Seal member 52 ... Anode electrode sheet 54 ... Cathode electrode sheet 56 ... Through hole 60 ... Servo press machine

Claims (2)

A first electrode is provided on one surface of the solid polymer electrolyte membrane, a second electrode is provided on the other surface of the solid polymer electrolyte membrane, and the planar dimensions of the first electrode are A step MEA set to a dimension larger than the planar dimension of the second electrode;
A resin frame member bonded to the outer peripheral surface of the solid polymer electrolyte membrane exposed to the outside of the second electrode by hot melt;
A method for producing an electrolyte membrane / electrode structure with a resin frame for a fuel cell, comprising:
The hot melt is a sheet-like hot melt in which a plurality of through-holes penetrating in the thickness direction is formed, and the sheet-like hot melt is disposed at a joint portion between the solid polymer electrolyte membrane and the resin frame member. A process of installing,
Heating the joint site where the sheet-like hot melt is disposed, and applying a load;
A process for producing an electrolyte membrane / electrode structure with a resin frame, comprising:   2. The method for manufacturing an electrolyte membrane / electrode structure with a resin frame according to claim 1, wherein the through hole has a diameter in a range of 20 [mu] m to 500 [mu] m.

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