JP6594809B2 - Step MEA with resin frame for fuel cell and manufacturing method thereof - Google Patents

Description

  The present invention provides a step MEA with a resin frame for a fuel cell, comprising: a step MEA sandwiching a solid polymer electrolyte membrane between a first electrode and a second electrode having different planar dimensions; and a resin frame member that goes around the outer periphery of the step MEA. And a manufacturing method thereof.

  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 constitute a power generation cell (unit fuel cell). The power generation cells are used as, for example, an in-vehicle fuel cell stack by stacking a predetermined number of power generation cells.

  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 the same plane size as the solid polymer electrolyte membrane. In other words, a so-called step MEA may be formed. At that time, in order to reduce the amount of use of a relatively expensive solid polymer electrolyte membrane 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 on the outer periphery Is adopted.

  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, a step MEA in which the planar dimension of the first electrode is set larger than the planar dimension of the second electrode, and a resin frame provided around the outer periphery of the solid polymer electrolyte membrane And a member.

  And the outer peripheral surface of the solid polymer electrolyte membrane which protrudes outward from the outer peripheral end of the 2nd electrode, and the resin frame member are adhere | attached with the contact bonding layer. For the adhesive layer, for example, a thermoplastic adhesive such as a hot melt adhesive is used.

JP, 2014-011125, A

  By the way, as described above, when a thermoplastic adhesive is used as the adhesive, the thermoplastic adhesive may be softened (gelled) during operation of the fuel cell. For this reason, the softened thermoplastic adhesive cannot withstand the pressure during operation and may flow out to the reaction gas flow path. Therefore, there is a problem that the reaction gas flow path is closed and the pressure loss increases.

  The present invention solves this type of problem, and provides a step MEA with a resin frame for a fuel cell that can reliably and easily prevent the outflow of an adhesive with a simple configuration and process, and a method for manufacturing the same. The purpose is to provide.

  The step MEA with a resin frame for a fuel cell and the manufacturing method thereof according to the present invention include the step MEA and a resin frame member. In the step MEA, a first electrode having a first electrode catalyst layer and a first gas diffusion layer is provided on one surface of the solid polymer electrolyte membrane, and the other surface of the solid polymer electrolyte membrane is provided with a first electrode. A second electrode having a two-electrode catalyst layer and a second gas diffusion layer is provided. The planar dimension of the first electrode is set to be larger than the planar dimension of the second electrode. The resin frame member is provided around the outer periphery of the solid polymer electrolyte membrane and has an inner bulging portion that bulges toward the second electrode.

  In the step MEA with a resin frame for a fuel cell, the outer peripheral surface of the solid polymer electrolyte membrane projecting outward from the outer peripheral end of the second electrode and the inner bulging portion are bonded with a thermoplastic adhesive. On the other hand, a thermosetting resin is disposed between the outer peripheral end of the second electrode and the inner peripheral end of the inner bulging portion.

  In addition, this manufacturing method includes a step of bonding the outer peripheral surface of the solid polymer electrolyte membrane projecting outward from the outer peripheral end of the second electrode and the inner bulging portion with a thermoplastic adhesive. In this manufacturing method, a thermosetting adhesive is disposed between the outer peripheral end of the second electrode and the inner peripheral end of the inner bulge portion, and the thermosetting adhesive is cured to form a thermosetting resin. It has a process.

  According to the present invention, the outer peripheral surface of the solid polymer electrolyte membrane and the inner bulging portion of the resin frame member are bonded by the thermoplastic adhesive, while the outer peripheral end of the second electrode and the inner bulging portion A thermosetting resin is disposed between the peripheral end. For this reason, even if the operating temperature rises during operation of the fuel cell and the thermoplastic adhesive softens, the thermoplastic adhesive softened by the thermosetting resin causes the outer peripheral end and the inner bulging portion of the second electrode to It does not flow out from between the inner peripheral edge.

  Therefore, it is possible to reliably and easily prevent the thermoplastic adhesive from flowing out with a simple configuration and process. Thereby, it is possible to prevent the softened thermoplastic adhesive from entering the reaction gas flow path, and it is possible to reliably suppress an increase in pressure loss of the reaction gas flow path.

It is a principal part disassembled perspective explanatory view of a polymer electrolyte power generation cell in which a step MEA with a resin frame according to an embodiment of 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 principal part cross-sectional explanatory drawing of the said level | step difference MEA with a resin frame. It is explanatory drawing of the state by which the thermoplastic adhesive and level | step difference MEA are arrange | positioned with respect to the resin frame member which comprises the said level | step difference MEA with a resin frame. It is operation | movement explanatory drawing when the said resin frame member and the said level | step difference MEA are joined. It is explanatory drawing of the state by which the thermosetting resin was arrange | positioned correspondingly between the said resin frame member and the said level | step difference MEA. It is operation | movement explanatory drawing when the said thermosetting resin is hot-pressed.

  As shown in FIGS. 1 and 2, a step MEA (resin framed electrolyte membrane / electrode structure) 10 with a resin frame for a fuel cell according to an embodiment of the present invention has a horizontally long (or vertically long) rectangular solid height. It is incorporated into a molecular power generation cell (fuel cell) 12. 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 step MEA 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 stepped MEA 10 with a rectangular resin frame includes a step MEA 10a. As shown in FIGS. 2 and 3, the step MEA 10a includes a solid polymer electrolyte membrane (cation exchange membrane) 18 that is a thin film of perfluorosulfonic acid containing moisture, for example. The solid polymer electrolyte membrane 18 is sandwiched between an anode electrode (first electrode) 20 and a cathode electrode (second electrode) 22. The solid polymer electrolyte membrane 18 can use an HC (hydrocarbon) electrolyte 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. 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.

  The anode electrode 20 includes 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 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 22a protrudes outward from the outer peripheral end 22be of the second gas diffusion layer 22b, has a larger planar dimension than the second gas diffusion layer 22b, and is larger than the solid polymer electrolyte membrane 18. Set to small planar dimensions.

  The second electrode catalyst layer 22a and the second gas diffusion layer 22b may be set to the same plane dimension, and the second electrode catalyst layer 22a is smaller in plane dimension than the second gas diffusion layer 22b. You may have.

  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 together with an ion conductive polymer binder. The second electrode catalyst layer 22a is formed, for example, by applying porous carbon particles having a platinum alloy supported on the surface thereof to the surface of the second gas diffusion layer 22b together with an ion conductive polymer binder.

  The first gas diffusion layer 20b and the second gas diffusion layer 22b are formed of carbon paper, carbon cloth, or the like. 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 18 a and 18 b of the solid polymer electrolyte membrane 18.

  The step MEA 10 with a resin frame includes a resin frame member (including a resin film) 24 that circulates around the outer periphery of the solid polymer electrolyte membrane 18 and is bonded to the anode electrode 20 and the cathode electrode 22.

  The resin frame member 24 includes, for example, PPS (polyphenylene sulfide), PPA (polyphthalamide), PEN (polyethylene naphthalate), PES (polyether sulfone), 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 frame shape and, as shown in FIG. 3, an outer peripheral edge portion 24a having a thickness t1 extending inward from the outer peripheral end portion is provided. A shelf 24b that abuts on the outer peripheral surface 18be of the solid polymer electrolyte membrane 18 via the first stepped portion 24s1 is provided at the inner end of the outer peripheral edge 24a. The shelf 24b has a thickness t2, and the thickness t2 is set to a dimension (thin) that is smaller than the thickness t1 (t1> t2).

  A thin-walled inner bulging portion 24c that bulges toward the cathode electrode 22 via the second step portion 24s2 is provided at the inner end portion of the shelf portion 24b. The inner bulging portion 24c has a thickness t3, and the thickness t3 is set to a dimension (thin) smaller than the thickness t2 (t2> t3). The inner peripheral end 24ce of the inner bulging portion 24c and the outer peripheral end 22be of the cathode electrode 22 are separated by a distance L.

  The outer peripheral edge 24a of the resin frame member 24 may be provided with a protrusion 24t protruding in the thickness direction on the surface on the anode electrode 20 side. The protrusion 24t is melted to impregnate the outer peripheral edge of the first gas diffusion layer 20b of the anode electrode 20 with resin.

  As shown in FIGS. 2 and 3, a filling chamber 26 is provided between the inner bulging portion 24c and the outer peripheral surface 18be of the solid polymer electrolyte membrane 18, and the filling chamber 26 is provided with a thermoplastic adhesive. Agent 28 is disposed. As the thermoplastic adhesive 28, a thermoplastic resin, for example, a hot melt agent such as an acrylic resin, an ester resin, or a styrene resin is used. A thermosetting adhesive 30 is disposed between the inner peripheral end 24ce of the inner bulging portion 24c and the outer peripheral end 22be of the cathode electrode 22. For the thermosetting adhesive 30, for example, an epoxy resin, a silicone resin, a urethane resin, or the like is used. The thermosetting adhesive 30 forms a thermosetting resin after being cured.

  As shown in FIG. 1, one end edge of the power generation cell 12 in the direction of arrow B (horizontal direction) is individually communicated in the direction of arrow A (stacking direction). An inlet communication hole 36a and a fuel gas outlet communication hole 38b are provided. The oxidant gas inlet communication hole 34a supplies an oxidant gas, for example, an oxygen-containing gas, while the cooling medium inlet communication hole 36a supplies a cooling medium. The fuel gas outlet communication hole 38b discharges fuel gas, for example, hydrogen-containing gas. The oxidant gas inlet communication hole 34a, the cooling medium inlet communication hole 36a, and the fuel gas outlet communication hole 38b are arranged in an arrow C direction (vertical direction).

  A fuel gas inlet communication hole 38a for supplying fuel gas, a cooling medium outlet communication hole 36b for discharging a cooling medium, and a cooling medium outlet communication hole 36b for individually communicating in the direction of arrow A to the other end edge of the power generation cell 12 in the direction of arrow B, An oxidant gas outlet communication hole 34b for discharging the oxidant gas is provided. The fuel gas inlet communication hole 38a, the coolant outlet communication hole 36b, and the oxidant gas outlet communication hole 34b are arranged in the direction of arrow C.

  An oxidant gas flow path 40 communicating with the oxidant gas inlet communication hole 34a and the oxidant gas outlet communication hole 34b is provided on the surface 16a of the second separator 16 facing the step MEA 10 with a resin frame. The oxidant gas channel 40 has a plurality of linear channel grooves (or wavy channel grooves) extending in the direction of arrow B.

  A fuel gas passage 42 communicating with the fuel gas inlet communication hole 38a and the fuel gas outlet communication hole 38b is provided on the surface 14a of the first separator 14 facing the step MEA 10 with the resin frame. The fuel gas flow channel 42 has a plurality of linear flow channel grooves (or wavy flow channel grooves) extending in the arrow B direction.

  Between the surface 14b of the first separator 14 and the surface 16b of the second separator 16 adjacent to each other, a cooling medium flow path 44 communicating with the cooling medium inlet communication hole 36a and the cooling medium outlet communication hole 36b is indicated by an arrow B. It is formed extending in the direction.

  As shown in FIGS. 1 and 2, the first seal member 46 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 48 is integrated with the surfaces 16 a and 16 b of the second separator 16 around the outer peripheral end of the second separator 16.

  As shown in FIG. 2, the first seal member 46 includes a first convex seal 46 a that abuts on the outer peripheral edge 24 a of the resin frame member 24 constituting the step MEA 10 with a resin frame. The first seal member 46 has a second convex seal 46 b that contacts the second seal member 48 of the second separator 16. The second seal member 48 constitutes a flat seal portion 48f whose surface abutting on the second convex seal 46b extends with a uniform thickness along the separator surface. Instead of the second convex seal 46b, the second seal member 48 may be provided with a convex seal (not shown), while the first seal member 46 may be configured with a flat seal portion.

  For the first seal member 46 and the second seal member 48, for example, EPDM, NBR, fluorine rubber, 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 manufacturing the step MEA 10 with a resin frame according to the present embodiment will be described below.

  First, as shown in FIG. 4, the resin frame member 24 is injection-molded using a mold (not shown), while the step MEA 10a is produced. A frame-shaped thermoplastic adhesive 28 is prepared, and the thermoplastic adhesive 28 is disposed on the inner bulging portion 24 c of the resin frame member 24. Further, the step MEA 10 a is disposed on the thermoplastic adhesive 28 with the cathode electrode 22 facing the resin frame member 24. As the thermoplastic adhesive 28, a sheet-like hot melt is preferable.

  Therefore, as shown in FIG. 5, the step MEA 10a and the resin frame member 24 are subjected to hot pressing. Therefore, the thermoplastic adhesive 28 is heated and melted, and the inner bulging portion 24 c of the resin frame member 24 and the outer peripheral surface 18 be of the solid polymer electrolyte membrane 18 are temporarily bonded. On the other hand, the outer peripheral surface 18be of the solid polymer electrolyte membrane 18 is in direct contact with the shelf 24b of the resin frame member 24.

  Next, as shown in FIG. 6, a sheet-like thermosetting adhesive 30 having a frame shape is prepared, and the thermosetting adhesive 30 is formed between the inner peripheral end 24 ce of the inner bulging portion 24 c and the cathode electrode 22. It arrange | positions between outer periphery ends 22be. In this state, as shown in FIG. 7, a thermosetting adhesive 30 is formed between the inner peripheral end 24 ce of the inner bulging portion 24 c and the outer peripheral end 22 be of the cathode electrode 22 by performing a hot press process. Is cured to obtain a temporary adhesive body.

  This temporary adhesive body is placed in a furnace (not shown) and annealed (annealed), and the thermosetting adhesive 30 is cured by annealing. Thereby, the step MEA 10a and the resin frame member 24 are integrated, and the step MEA 10 with a resin frame is manufactured.

  As shown in FIG. 2, the step MEA 10 with the resin frame is sandwiched between the first separator 14 and the second separator 16. The second separator 16 contacts the inner bulging portion 24c of the resin frame member 24, and applies a load in the stacking direction to the step MEA 10 with the 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 34a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 38a. Supplied. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 36a.

  Therefore, the oxidant gas is introduced into the oxidant gas flow path 40 of the second separator 16 from the oxidant gas inlet communication hole 34a, moves in the arrow B direction, 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 42 of the first separator 14 from the fuel gas inlet communication hole 38a. The fuel gas moves in the direction of arrow B along the fuel gas flow path 42 and is supplied to the anode electrode 20 of the step MEA 10a.

  Therefore, in the step MEA 10a, the oxidant gas supplied to the cathode electrode 22 and the fuel gas supplied to the anode electrode 20 are consumed by the electrochemical reaction in the second electrode catalyst layer 22a and the first electrode catalyst layer 20a. Then, power generation is performed.

  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 34b. 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 38b.

  The cooling medium supplied to the cooling medium inlet communication hole 36 a is introduced into the cooling medium flow path 44 between the first separator 14 and the second separator 16 and then flows in the direction of arrow B. This cooling medium is discharged from the cooling medium outlet communication hole 36b after cooling the step MEA 10a.

  As described above, when the power generation cell 12 is operated (power generation), the temperature of the step MEA 10 with a resin frame rises and the thermoplastic adhesive 28 may be softened. The softened thermoplastic adhesive 28 may flow into the outside of the step MEA 10 with a resin frame, for example, into the oxidant gas flow path 40.

  Here, in this embodiment, as shown in FIGS. 2 and 3, thermosetting is performed between the inner peripheral end 24 ce of the inner bulging portion 24 c constituting the resin frame member 24 and the outer peripheral end 22 be of the cathode electrode 22. The adhesive 30 is arrange | positioned. For this reason, even if the thermoplastic adhesive 28 is softened during operation of the power generation cell 12, the thermosetting adhesive 30 is cured. Therefore, the softened thermoplastic adhesive 28 is prevented by the thermosetting adhesive 30 and does not flow out between the inner peripheral end 24ce of the inner bulging portion 24c and the outer peripheral end 22be of the cathode electrode 22.

  Therefore, it is possible to reliably and easily prevent the thermoplastic adhesive 28 from flowing out with a simple configuration and process. Thereby, for example, the softened thermoplastic adhesive 28 can be prevented from entering the oxidant gas flow path 40, and the pressure loss of the oxidant gas flow path 40 is reliably suppressed from increasing. The effect that it becomes possible is acquired.

10 ... Step MEA with resin frame 10a ... Step MEA
DESCRIPTION OF SYMBOLS 12 ... Power generation cell 14, 16 ... Separator 18 ... Solid polymer electrolyte membrane 18be ... Outer peripheral surface 20 ... Anode electrode 20a, 22a ... Electrode catalyst layer 20b, 22b ... Gas diffusion layer 22be ... Outer peripheral end 22 ... Cathode electrode 24 ... Resin frame Member 24a ... Outer peripheral edge portion 24b ... Shelf portion 24c ... Inner bulging portion 24ce ... Inner peripheral edge 28 ... Thermoplastic adhesive 30 ... Thermosetting adhesive 34a ... Oxidant gas inlet communication hole 34b ... Oxidant gas outlet communication hole 36a ... Cooling medium inlet communication hole 36b ... Cooling medium outlet communication hole 38a ... Fuel gas inlet communication hole 38b ... Fuel gas outlet communication hole 40 ... Oxidant gas flow path 42 ... Fuel gas flow path 44 ... Cooling medium flow path

Claims (2)

A first electrode having a first electrode catalyst layer and a first gas diffusion layer is provided on one surface of the solid polymer electrolyte membrane, and a second electrode catalyst layer is provided on the other surface of the solid polymer electrolyte membrane. And a second electrode having a second gas diffusion layer, and the planar dimension of the first electrode is a step MEA set to be larger than the planar dimension of the second electrode;
A resin frame member provided around the outer periphery of the solid polymer electrolyte membrane and having an inner bulging portion bulging toward the second electrode;
A step MEA with a resin frame for a fuel cell comprising:
A thermoplastic adhesive that bonds the outer peripheral surface of the solid polymer electrolyte membrane projecting outward from the outer peripheral end of the second electrode and the inner bulge;
A thermosetting resin disposed between the outer peripheral end of the second electrode and the inner peripheral end of the inner bulge;
A step MEA with a resin frame for a fuel cell, comprising: A first electrode having a first electrode catalyst layer and a first gas diffusion layer is provided on one surface of the solid polymer electrolyte membrane, and a second electrode catalyst layer is provided on the other surface of the solid polymer electrolyte membrane. And a second electrode having a second gas diffusion layer, and the planar dimension of the first electrode is a step MEA set to be larger than the planar dimension of the second electrode;
A resin frame member provided around the outer periphery of the solid polymer electrolyte membrane and having an inner bulging portion bulging toward the second electrode;
A method of manufacturing a step MEA with a resin frame for a fuel cell comprising:
Bonding the outer peripheral surface of the solid polymer electrolyte membrane projecting outward from the outer peripheral edge of the second electrode and the inner bulging portion with a thermoplastic adhesive;
A step of disposing a thermosetting adhesive between the outer peripheral end of the second electrode and an inner peripheral end of the inner bulging portion, and curing the thermosetting adhesive to form a thermosetting resin; ,
A method for producing a step MEA with a resin frame for a fuel cell, comprising:

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