JP2017068956A - Resin frame-attached electrolyte membrane-electrode structure for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to keep the thickness of an adhesive layer constant in operation and suppress the effusion of an adhesive by a simple structure.SOLUTION: A resin frame-attached electrolyte membrane-electrode structure 10 comprises: a stepped MEA 10a; and a resin frame member 24. The stepped MEA 10a has a cathode electrode 20 and an anode electrode 22 which is smaller than the cathode electrode 20 in plane dimension. The resin frame-attached electrolyte membrane-electrode structure further comprises an adhesive sheet 26 disposed between an exposed surface 18be of a solid polymer electrolyte film 18, which is exposed outwardly from the anode electrode 22, and a joint face 24as of the resin frame member 24. The adhesive sheet 26 has a mesh member 26m impregnated with a thermoplastic adhesive 26s.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electrolyte membrane / electrode structure 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 that goes around the outer periphery of the step MEA. About.

  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 constitutes a power generation cell (unit fuel cell) by being sandwiched between separators (bipolar plates). The power generation cells are used as, for example, an in-vehicle fuel cell stack by being stacked in 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.

  In the MEA with a resin frame, the resin frame member has a joint surface facing the exposed surface exposed to the outside of one gas diffusion layer of the solid polymer electrolyte membrane, and the exposed surface and the joint surface are made of an adhesive. Joined by layers. At that time, since heat and pressure are applied to the bonded portion, the thickness of the adhesive layer may not be effectively maintained.

  Therefore, for example, as disclosed in Patent Document 1, it is considered to use an adhesive containing resin beads. This adhesive has a load compression characteristic in which the thickness of the adhesive layer becomes thinner than the diameter of the resin beads due to the load applied when the fuel cells are stacked.

JP 2002-352845 A

  However, in the above adhesive containing resin beads, when a thermoplastic adhesive is used as the adhesive, the operating temperature range of the fuel cell may exceed the glass transition point of the thermoplastic adhesive. Therefore, the thermoplastic adhesive cannot withstand the operating pressure, and has a problem that it cannot gel and maintain the thickness of the adhesive layer. Moreover, the adhesive containing resin beads has a problem in that the outflow of the thermoplastic adhesive cannot be suppressed.

  The present invention solves this type of problem, and with a simple configuration, the thickness of the adhesive layer during operation can be kept constant, and the flow of the adhesive can be reliably suppressed. An object of the present invention is to provide an electrolyte membrane / electrode structure with a resin frame for a fuel cell.

  The electrolyte membrane / electrode structure with a resin frame for a fuel cell according to the present invention includes 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.

  And, between the other surface of the solid polymer electrolyte membrane and between the exposed surface exposed to the outside of the second electrode and the joint surface of the resin frame member facing the exposed surface, thermoplastic adhesion to the mesh member An adhesive sheet impregnated with the agent is provided.

  In the electrolyte membrane / electrode structure with a resin frame for a fuel cell, the mesh member is preferably configured by laminating a plurality of lattice-like membranes.

  According to the present invention, an adhesive sheet is provided in which a mesh member is impregnated with a thermoplastic adhesive. For this reason, even if the temperature range during operation of the fuel cell exceeds the glass transition point of the thermoplastic adhesive, the mesh member can reliably receive the operating pressure and keep the thickness of the adhesive sheet constant. It becomes possible to do. Moreover, the mesh member can favorably suppress the outflow of the adhesive. Here, the outflow means that the adhesive melts and flows out of the mesh member.

It is a principal part disassembled perspective explanatory view of the polymer electrolyte power generation cell in which the electrolyte membrane / electrode structure with a resin frame according to the present invention is incorporated. It is II-II sectional view explanatory drawing in FIG. 1 of the said electric power generation cell. It is a perspective explanatory view of the resin frame member which constitutes the resin membrane-attached electrolyte membrane electrode structure. It is a perspective explanatory view of a thermoplastic adhesive and a mesh member. FIG. 3 is a perspective explanatory view of an adhesive sheet body in which the mesh adhesive is impregnated with the thermoplastic adhesive. It is a perspective explanatory view of an adhesive sheet and level difference MEA. It is a perspective explanatory view of the level difference MEA in which the adhesive sheet is arranged and a resin frame member.

  As shown in FIGS. 1 and 2, an electrolyte membrane / electrode structure 10 with a resin frame according to an embodiment of the present invention is applied to a horizontally long (or vertically long) rectangular polymer electrolyte power generation cell (fuel cell) 12. 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. The step MEA 10a includes, for example, a solid polymer electrolyte membrane (cation exchange membrane) 18 in which a perfluorosulfonic acid thin film is impregnated with water, and a cathode electrode (first electrode) 20 sandwiching the solid polymer electrolyte membrane 18. And an anode electrode (second electrode) 22. The solid polymer electrolyte membrane 18 may use an HC (hydrocarbon) based electrolyte in addition to the fluorine based electrolyte.

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

  The cathode electrode 20 is provided with a first electrode catalyst layer 20a joined to one surface 18a of the solid polymer electrolyte membrane 18, and a first gas diffusion layer 20b laminated on the first electrode catalyst layer 20a. The first electrode catalyst layer 20a and the first gas diffusion layer 20b have the same planar dimensions and are set to the same (or less than) the same planar dimensions as the solid polymer electrolyte membrane 18.

  The anode electrode 22 includes a second electrode catalyst layer 22a joined to the surface 18b of the solid polymer electrolyte membrane 18, and a second gas diffusion layer 22b laminated on the second electrode catalyst layer 22a. The second electrode catalyst layer 22a and the second gas diffusion layer 22b are set to have a plane size smaller than the plane size of the solid polymer electrolyte membrane 18, and the second electrode catalyst layer 22a is formed of the second gas diffusion layer. It has a larger planar dimension than 22b. An exposed surface 18be exposed to the outside of the anode 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 is set to have a larger planar dimension than the second gas diffusion layer 22b. However, the second electrode catalyst layer 22a has the same planar dimension as the second gas diffusion layer 22b ( Or a small dimension).

  The first electrode catalyst layer 20a is formed, for example, by 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, for example, by uniformly applying porous carbon particles carrying a platinum alloy on the surface thereof to the surface of the second gas diffusion layer 22b. The first electrode catalyst layer 20a and the second electrode catalyst layer 22a are formed on the surface 18a and the surface 18b of the solid polymer electrolyte membrane 18.

  The electrolyte membrane / electrode structure 10 with a resin frame includes a film-like resin frame member (resin film) 24 bonded to the exposed surface 18be of the solid polymer electrolyte membrane 18. The resin frame member 24 may be formed in a relatively thick frame shape having substantially the same thickness as the thickness of the step MEA 10a.

  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), A silicone resin, a fluororesin, or m-PPE (modified polyphenylene ether resin) is used. The resin frame member 24 is further made of PET (polyethylene terephthalate), PBT (polybutylene terephthalate), modified polyolefin, or the like.

  As shown in FIGS. 2 and 3, the resin frame member 24 has an inner thin portion 24 a that is formed in a thin shape via a step portion 24 s and extends toward the cathode electrode 20. The step portion 24s is set at a position separated by a distance S1 inside the outer peripheral end portion of the exposed surface 18be of the solid polymer electrolyte membrane 18. The inner thin portion 24 a is provided with a bonding surface 24 as opposed to the exposed surface 18 be of the solid polymer electrolyte membrane 18.

  The inner peripheral end face 24ae of the inner thin portion 24a terminates with a distance S2 away from the outer peripheral end face 22be of the second gas diffusion layer 22b constituting the anode electrode 22. The resin frame member 24 has an outer peripheral thick portion 24b on the outer peripheral side of the step portion 24s, and a part of the inner peripheral side of the outer peripheral thick portion 24b is on the tip side of the exposed surface 18be of the solid polymer electrolyte membrane 18 Abut.

  An adhesive sheet 26 is provided between the exposed surface 18be of the solid polymer electrolyte membrane 18 and the bonding surface 24as of the resin frame member 24. The adhesive sheet 26 is configured by impregnating a mesh member 26m with a thermoplastic adhesive 26s. The mesh member 26m is formed by laminating a plurality of stretched PTFE (polytetrafluoroethylene) lattice films (membranes), for example. The inner peripheral end portion of the mesh member 26m is disposed at a position that overlaps with the outer peripheral end portion of the second electrode catalyst layer 22a and is in contact with the outer peripheral end surface 22be of the second gas diffusion layer 22b or slightly spaced from the outer peripheral end surface 22be. Is done. The second electrode catalyst layer 22a is exposed to the outside from between the inner peripheral end surface 24ae and the outer peripheral end surface 22be of the resin frame member 24. Note that the mesh member 26m may not be provided in the entire region between the step portion 24s of the resin frame member 24 and the outer peripheral end face 22be of the second gas diffusion layer 22b.

  In addition, when the 2nd electrode catalyst layer 22a is set to the same planar dimension (or small dimension) as the 2nd gas diffusion layer 22b, the inner peripheral edge part of the mesh member 26m is 2nd electrode catalyst layer 22a. The second electrode catalyst layer 22a is not exposed to the outside from between the inner peripheral end face 24ae and the outer peripheral end face 22be of the resin frame member 24.

  The thermoplastic adhesive 26 s is a hot melt adhesive that is solid at room temperature but has a property of being liquefied by being heated and melted and forming a joined state by being cooled and solidified. As the hot melt adhesive, an acrylic, urethane, epoxy or ester adhesive is employed.

  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 actually arranged in the first separator 14 and the second separator 16 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 actually arranged in the first separator 14 and the second separator 16 in the direction of arrow C.

  The surface 14a of the first separator 14 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 direction of arrow B. An oxidant gas flow path 36 is provided.

  The surface 16a of the second separator 16 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 method for producing the resin frame-attached electrolyte membrane / electrode structure 10 will be described below.

  First, the adhesive sheet 26 is produced. Specifically, as shown in FIG. 4, a sheet-like or liquid thermoplastic adhesive 26s is prepared, while a porous mesh-like mesh member 26m is prepared. A flat adhesive sheet 26A is formed by impregnating the mesh member 26m with the thermoplastic adhesive 26s (see FIG. 5). The adhesive sheet body 26A is cut into a predetermined shape, that is, a frame shape so as to be applied to the electrolyte membrane / electrode structure 10 with a resin frame, and the adhesive sheet 26 is produced.

  On the other hand, the step MEA 10a is manufactured, and the resin frame member 24 is injection-molded using a mold (not shown). As shown in FIG. 3, the resin frame member 24 has a thin inner thin portion 24a.

  Next, as shown in FIG. 6, the adhesive sheet 26 is disposed on the exposed surface 18be of the solid polymer electrolyte membrane 18 constituting the step MEA 10a. The adhesive sheet 26 can be temporarily bonded to the exposed surface 18be.

  And as shown in FIG. 7, level | step difference MEA10a is laminated | stacked on the resin frame member 24 in the state by which the adhesive sheet 26 is arrange | positioned. Therefore, the adhesive sheet 26 is disposed between the exposed surface 18be of the solid polymer electrolyte membrane 18 and the bonding surface 24as of the resin frame member 24.

  In this state, the exposed surface 18be of the solid polymer electrolyte membrane 18 and the bonding surface 24as of the resin frame member 24 are subjected to heat treatment for heating the adhesive sheet 26 to a predetermined temperature, and pressure for applying a predetermined load. Processing is performed at the same time. Accordingly, the thermoplastic adhesive 26s contained in the adhesive sheet 26 is heated and melted, and the exposed surface 18be and the bonding surface 24as are bonded. Thereby, the electrolyte membrane and electrode structure 10 with a resin frame is manufactured.

  In FIG. 6, the adhesive sheet 26 is disposed on the step MEA 10 a, but instead, the adhesive sheet 26 may be disposed on the resin frame member 24. Next, the resin frame member 24 on which the adhesive sheet 26 is disposed may be joined to the step MEA 10a by the adhesive sheet 26 in a state of being disposed on the step MEA 10a.

  As shown in FIG. 2, the resin membrane-attached electrolyte membrane / electrode structure 10 is sandwiched between the first separator 14 and the second separator 16. The second separator 16 contacts the inner thin portion 24 a of the resin frame member 24 and applies a load to the electrolyte membrane / electrode structure 10 with a resin frame together with the first separator 14. Furthermore, a predetermined number of power generation cells 12 are stacked to form a fuel cell stack, and a tightening load is applied between end plates (not shown).

  The operation of the power generation cell 12 configured as described above will be described 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 first separator 14, moves in the direction of arrow B, and is supplied to the cathode electrode 20 of the step MEA 10a. On the other hand, the fuel gas is introduced into the fuel gas flow path 38 of the second separator 16 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 22 of the step MEA 10a.

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

  Next, the oxidant gas consumed by being supplied to the cathode electrode 20 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 22 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.

  In this case, in this embodiment, as shown in FIG. 2, an adhesive sheet 26 is disposed between the exposed surface 18be of the solid polymer electrolyte membrane 18 and the bonding surface 24as of the resin frame member 24. In the adhesive sheet 26, the mesh member 26m is impregnated with the thermoplastic adhesive 26s.

  For this reason, even if the temperature range during operation of the power generation cell 12 exceeds the glass transition point of the thermoplastic adhesive 26s, the mesh member 26m can reliably receive the operating pressure. Therefore, the thickness of the adhesive sheet 26 can be kept constant, and the mesh member 26m can effectively suppress the outflow of the thermoplastic adhesive 26s. Here, the outflow means that the thermoplastic adhesive 26s is melted and flows out of the mesh member 26m.

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 ... Cathode electrode 20a, 22a ... Electrode catalyst layer 20b, 22b ... Gas diffusion layer 22 ... Anode electrode 24 ... Resin frame member 24a ... Inside Thin portion 24as ... joint surface 24b ... outer peripheral thick portion 24s ... step portion 26 ... adhesive sheet 26m ... mesh member 26s ... thermoplastic adhesive 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 flow path 38 ... Fuel gas flow path 40 ... Cooling medium flow path 42, 44 ... Sealing member

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 provided around the outer periphery of the solid polymer electrolyte membrane;
An electrolyte membrane / electrode structure with a resin frame for a fuel cell comprising:
Among the other surface of the solid polymer electrolyte membrane, the mesh member is heated between the exposed surface exposed to the outside of the second electrode and the joint surface of the resin frame member facing the exposed surface. An electrolyte membrane / electrode structure with a resin frame for a fuel cell, wherein an adhesive sheet impregnated with a plastic adhesive is provided.   2. The electrolyte membrane / electrode structure with a fuel cell resin frame according to claim 1, wherein the mesh member is formed by laminating a plurality of lattice-like membranes. 3. Electrolyte membrane / electrode structure.

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