JP2001015127A - Electrolytic film/electrode bonded body and solid polyelectrolyte type fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a fuel cell at low cost by forming a solid polymer electrolytic film region in a central part and an anode electrode and a cathode electrode in both principal faces of an electrolytic film/insulating film bonded sheet having insulating film regions in its circumference. SOLUTION: The edge part of an electrolytic film 1 is sandwiched between two insulating films 10A formed into a frame shape by hollowing out the central parts of the insulating films, whose one sides are longer than that of the solid polymer electrolytic film 1, bonded together with adhesive so as to be formed into a solid polymer electrolytic film/insulating film bonded sheet 13. Then, an electrode catalyst layer 2 is bonded and formed in the solid polyelectrolyte regions on the both major faces of the bond sheet 13 by thermocompression bonding. After adhesive is applied to the insulating film regions on the both major faces of the bonded sheet 13, electrode substrates 3 are laminated and bonded so that an electrolytic film/electrode bonded body 6 is provided. A plastic sheet composed of polyethylene terephthalate, polyethylene, etc., and a rubber sheet are used for the insulating film 10A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cell structure of a solid polymer electrolyte fuel cell, and more particularly to a structure of a joined body of a polymer electrolyte membrane and an electrode.

[0002]

2. Description of the Related Art As is well known, a solid polymer electrolyte fuel cell has an anode electrode and a cathode electrode formed on both main surfaces of a solid polymer electrolyte membrane, and a fuel gas and an oxidizing gas are applied to each of the electrodes. It is a type of power generation device that generates power by supplying each.

[0003] The solid polymer electrolyte membrane uses a polystyrene-based cation exchange membrane having a sulfonic acid group as a cation conductive membrane, a mixed membrane of fluorocarbon sulfonic acid and polyvinylidene fluoride, and a trifluorocarbon matrix used as a trifluorocarbon matrix. Grafted ethylene,
Alternatively, a perfluorosulfonic acid resin film or the like is used.

[0004] The solid polymer electrolyte membrane has a proton (hydrogen ion) exchange group in the molecule, exhibits a specific resistance of 20 Ω · cm or less at room temperature by being saturated with water, and functions as a proton conductive electrolyte. The electrode base material is a porous body and functions as a supply / discharge means and a current collector for the reaction gas (fuel gas and oxidizing gas) of the fuel cell. At the anode electrode or the cathode electrode, a three-phase interface of a gas phase, a liquid phase, and a solid phase is formed, and the following electrochemical reaction occurs by the catalytic action of the electrode catalyst.

Anode: H ₂ → 2H ⁺ + 2e ⁻ Cathode: 1 / 2O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O In the anode, protons and electrons are generated from hydrogen gas supplied from outside the fuel cell. Protons move inside the solid polymer electrolyte membrane toward the cathode. On the other hand, at the cathode, oxygen in the oxidant gas supplied from the outside of the fuel cell reacts with protons moving from the anode through the solid polymer electrolyte membrane and electrons passing through the external circuit to generate water. I do.

FIG. 5 is a sectional view showing a single cell structure of a conventional polymer electrolyte fuel cell. Electrode catalyst layers 2 are integrated on both main surfaces of the solid polymer electrolyte membrane 1 by thermocompression bonding using a hot press.
Is adhered to the solid polymer electrolyte membrane 1 with an adhesive in an edge vicinity region 7 to form a solid polymer electrolyte membrane / electrode assembly (hereinafter, referred to as an electrolyte membrane / electrode assembly) 6. Further, separators 5 are arranged on both sides of the electrolyte membrane / electrode assembly 6 to form a single cell. As a material of the electrode substrate 3, a porous conductive sheet material, for example, carbon paper or the like is used. The separator 5 is made of a gas-impermeable material, and has irregularities functioning as a reaction gas passage on the main surface on the side in contact with the electrolyte membrane / electrode assembly 6.

As shown in FIG. 5, the dimensions of the electrode substrate 3 and the solid polymer electrolyte membrane 1 are the same as viewed from the laminating direction, or the electrode substrate 3 is smaller than the solid polymer electrolyte membrane 1. It is formed as follows. By setting the solid polymer electrolyte membrane 1 interposed between the cathode-side electrode base material 3 and the anode-side electrode base material 3 to be equal to or larger than the two electrode base materials 3 in this manner, 3 prevents short circuit from occurring.

The reaction gas supplied to each electrode 4 is introduced into and discharged from each unit cell through a reaction gas inlet and outlet (not shown) provided in the separator 5. Since the reaction gas inlet and outlet are formed in a portion of the solid polymer electrolyte membrane 1 corresponding to the edge vicinity region 7 where the electrode catalyst layer 2 is not formed, the vicinity of the edge of the solid polymer electrolyte membrane 1 is formed. Area 7
Needs to have a width (a distance from an edge to a portion where the electrode catalyst layer 2 is formed) required for the above.

[0009]

As described above, in the conventional solid polymer electrolyte fuel cell, the solid polymer electrolyte membrane 1 has the electrode catalyst layer 2 around the region where the electrode catalyst layer 2 is formed. Are formed near the edge 7 where no is formed. However, since the solid polymer electrolyte membrane 1 is expensive, it is desirable not to provide a region of the solid polymer electrolyte membrane 1 where the electrode catalyst layer 2 is not formed or to make the region as small as possible.

Therefore, the present invention provides a low-cost electrolyte / electrode assembly 6 and a solid polymer electrolyte fuel cell in which the amount of the expensive solid polymer electrolyte membrane 1 used is reduced without causing a short circuit between the electrodes 4. To provide.

[0011]

According to the present invention, there is provided a solid polymer electrolyte membrane / insulating film adhesive having a solid polymer electrolyte membrane region at a central portion and an insulating film region at a peripheral portion thereof. An electrolyte membrane / electrode assembly is formed by forming an anode electrode and a cathode electrode on both main surfaces of the sheet. The insulating film region is formed of either a plastic sheet or a rubber sheet.

In the electrolyte membrane / electrode assembly according to the present invention, the cost can be reduced by using a small area solid polymer electrolyte membrane, and the solid polymer electrolyte membrane can be used even if a small area solid polymer electrolyte membrane is used. If the size of the solid polymer electrolyte membrane / insulating film adhesive sheet is made larger than the electrode substrate by providing the insulating film in a frame shape around the electrolyte membrane, the solid polymer electrolyte membrane / insulating film is formed. A short circuit between the anode electrode and the cathode electrode provided on both main surfaces of the adhesive sheet can also be prevented.

Further, in the present invention, if a solid polymer electrolyte fuel cell is constituted by sandwiching the above-mentioned electrolyte membrane / electrode assembly with a separator, an inexpensive solid polymer electrolyte fuel cell can be obtained. Can be obtained.

Further, in the polymer electrolyte fuel cell according to the present invention, a region near the edge of the main surface of the separator in contact with the electrolyte membrane / electrode assembly is formed by the solid polymer electrolyte membrane / insulating film adhesive sheet. If laminated directly in contact with the insulating film region, the rubber seal for preventing gas leakage, which was conventionally inserted at the junction between the anode-side separator and the cathode-side separator, becomes unnecessary, and the number of parts and the manufacturing process can be simplified. Can be.

[0015]

FIG. 1 is a view showing the structure of a solid polymer electrolyte membrane / insulating film adhesive sheet used for an electrolyte membrane / electrode assembly according to the present invention, and (a) to (c) of FIG. (D) shows a cross-sectional view of one surface of the sheet as viewed from above. This solid polymer electrolyte membrane / insulating membrane adhesive sheet is used in place of the solid polymer electrolyte membrane used in the conventional electrolyte membrane / electrode assembly. In FIG. 1, the same components as those of the conventional structure are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1A shows a solid polymer electrolyte formed of two insulating films 10A formed by cutting out a central portion of an insulating film having one side longer than the solid polymer electrolyte membrane 1 and forming a frame shape. By sandwiching the edges of the membrane 1 and bonding them with an adhesive, one solid polymer electrolyte membrane having a solid polymer electrolyte membrane region 11 at the center and an insulating film region 12 at the periphery is formed.
3 shows a cross-sectional structure in the thickness direction of the insulating film adhesive sheet 13 formed. (B) Similarly, the solid polymer electrolyte 1 is adhered to the central portion of one insulating film 10A having a frame shape by hollowing out the central portion with an adhesive, thereby bonding one solid polymer electrolyte membrane / insulating film. A sheet 13 is shown. (C) shows a case in which the solid polymer electrolyte membrane 1 is disposed at the center of one insulating film 10A having a framed shape by hollowing out the center, and furthermore, necessary for adhering the two. This is a cross-sectional structure of a structure in which insulating films 10B having a size are stacked and adhered to each other and formed on one solid polymer electrolyte membrane / insulating film adhesive sheet 13.

FIG. 2 is a cross-sectional view of the structure when the electrode catalyst layer 2 is formed on the solid polymer electrolyte membrane / insulating film adhesive sheet 13. The method for forming the electrode catalyst layer 2 includes, for example, applying the electrode catalyst layer 2 to the solid polymer electrolyte regions 11 on both main surfaces of the solid polymer electrolyte membrane / insulating film adhesive sheet 13 shown in FIG. There is a method of bonding and forming by pressing, and the cross-sectional structure of the solid polymer electrolyte membrane / insulating film sheet 13 on which the electrode catalyst layer 2 is formed in this manner is shown in FIG.
It is shown in FIG. Alternatively, before the solid polymer electrolyte membrane / insulating film adhesive sheet 13 is prepared, the electrode catalyst layer 2 is bonded to the solid polymer electrolyte membrane 1 by thermocompression bonding using a hot press. A diagram showing a cross-sectional structure of the solid polymer electrolyte membrane / insulating film sheet 13 on which the electrode catalyst layer 2 is formed in this manner may be bonded to the solid polymer electrolyte membrane 1 on which the electrode catalyst layer 2 is formed. FIG. 2 (b).

After applying an adhesive to the insulating film regions 12 on both main surfaces of the solid polymer electrolyte membrane / insulating film adhesive sheet 13 on which the electrode catalyst layer 2 is formed as described above, the electrode substrate 3 is laminated. Then, the electrolyte membrane / electrode assembly of the present invention is obtained. An example is shown in FIG. FIG.
The electrolyte membrane / electrode assembly 6 shown in (c) is obtained by forming the electrode catalyst layer 2 on the solid polymer membrane / insulating film adhesive sheet 13 shown in FIG. It is.

In forming the solid polymer electrolyte membrane / insulating film adhesive sheet 13, the method of bonding the solid polymer electrolyte membrane to the insulating film formed into a frame shape by cutting out the center portion as described above is used. In addition, there is a method of bonding a strip-shaped insulating film around the solid polymer electrolyte membrane in a frame shape.

In the former method, a plurality of predetermined portions of the large-area insulating film 10C are cut out as shown in FIG. 3, and the solid polymer electrolyte membrane 1 is bonded to the cut-out portions. If it is separated as shown, it can be easily mass-produced.

Next, FIG. 4 shows an embodiment in which a solid polymer electrolyte fuel cell is manufactured using the solid polymer electrolyte membrane / insulating film adhesive sheet shown in FIGS. 1 (a) and 2 (a).
Shown in

FIG. 4 (a) shows the solid polymer electrolyte membrane / insulating film on both surfaces of the solid polymer electrolyte membrane / insulating film adhesive sheet 13 on which the electrode catalyst layer 2 is formed as shown in FIG. 2 (a). When an electrode substrate 3 having the same dimensions as the membrane adhesive sheet is provided to form an electrolyte membrane / electrode assembly 6, and the electrolyte membrane / electrode assembly 6 is sandwiched between separators 5 to form a solid polymer electrolyte fuel cell. FIG. As shown in the figure, the two separators are in contact with each other at their edge portions, but a rubber seal member 14 is interposed in order to prevent the leakage of the reaction gas from the joint surface.

On the other hand, FIG. 4B shows the solid polymer electrolyte membrane / insulating film adhesive sheet 13 on which the electrode catalyst layer 2 is formed as shown in FIG. An electrode substrate 3 having a size slightly smaller than the electrolyte membrane / insulating film adhesive sheet 13 is provided to form an electrolyte membrane / electrode assembly 6,
Further, an embodiment in which the electrolyte membrane / electrode assembly 6 is sandwiched between separators 5 is shown. In the present configuration, the region near the edge of the main surface of the anode-side and cathode-side separators 5 on the side facing the electrolyte membrane / electrode assembly 6 is the insulating film region 12 of the solid polymer electrolyte membrane / insulating film adhesive sheet 13 ( Since it is laminated directly in contact with FIG. 1), there is an advantage that the rubber seal member 14 for preventing gas leakage used in the configuration of FIG. 4A can be omitted.

The separators 5 of these solid polymer electrolyte fuel cells have irregularities which function as flow grooves for fuel gas and oxidizing gas which are guided to the anode electrode and the cathode electrode and used for the power generation reaction. Have been. A reaction gas inlet 8 for introducing a reaction gas into the reaction gas flow groove is formed in a portion of the separator 5 corresponding to the insulating film region 12 of the solid polymer electrolyte membrane / insulating film adhesive sheet 13.

In the present invention, as the insulating film (10A to 10C) used for the solid polymer electrolyte membrane / insulating film adhesive sheet 13, for example, a general-purpose plastic sheet made of polyethylene terephthalate, polyethylene, or the like, a rubber sheet, or the like is used. . Further, as the electrode base material 3, for example, a porous conductive sheet such as carbon paper can be used.

[0026]

As described above, according to the present invention, a solid polymer electrolyte membrane / insulating film adhesive sheet is formed by arranging and bonding a frame-like insulating film in the vicinity of the edge of the solid polymer electrolyte membrane. The electrolyte membrane / electrode assembly in which the anode electrode and the cathode electrode are disposed via this, (1) a solid material in which the amount of expensive solid polymer electrolyte membrane used is greatly reduced Since a polymer membrane / electrode assembly can be manufactured, cost reduction can be achieved.

(2) Since the periphery of the solid polymer electrolyte membrane is protected by the insulating film, in the manufacturing process of the electrolyte membrane / electrode assembly, handling by manual operation becomes particularly easy and power generation performance is reduced. The yield was improved by reducing the influence of damage to the solid polymer electrolyte membrane.

(3) In the case where the electrolyte membrane / electrode assembly according to the present invention is sandwiched between separators to form a single cell, both the solid polymer electrolyte membrane / insulating film area of the insulating film adhesive sheet may be used. If a configuration is adopted in which the region near the edge of the separator is directly contacted and laminated on the main surface, a rubber seal material for preventing gas leakage, which has conventionally been interposed at the joint portion between the anode side separator and the cathode side separator, becomes unnecessary,
The cell structure is simplified, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the structure of a solid polymer electrolyte membrane / insulating film adhesive sheet used for an electrolyte membrane / electrode assembly of a solid polymer electrolyte fuel cell according to an embodiment of the present invention.

FIG. 2 is a structural cross-sectional view of an electrolyte membrane / electrode assembly according to the present invention in a manufacturing process.

FIG. 3 is a diagram showing an example of a mass production process of the solid polymer electrolyte membrane / insulating film adhesive sheet according to the present invention.

FIG. 4 is a cross-sectional view showing the structure of a solid polymer electrolyte fuel cell according to the present invention.

FIG. 5 is a cross-sectional view showing a single cell structure of a conventional solid polymer electrolyte fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solid polymer electrolyte membrane 2 Electrode catalyst layer 3 Electrode base material 4 Electrode 5 Separator 6 Electrolyte membrane / electrode assembly 7 Edge vicinity area 8 Reaction gas inlet 9 Reaction gas outlet 10 Insulation film 11 Solid polymer electrolyte membrane area 12 Insulating film area 13 Solid polymer electrolyte membrane / insulating film adhesive sheet 14 Rubber seal material

Claims (4)

[Claims] 1. A solid polymer electrolyte membrane / insulating film adhesive sheet having a solid polymer electrolyte membrane region in a central portion and an insulating film region in a peripheral portion thereof, and an anode electrode and a cathode formed on both main surfaces of the sheet. An electrolyte membrane / electrode assembly comprising an electrode. 2. The electrolyte membrane / electrode assembly according to claim 1, wherein said insulating film region is made of one of a plastic sheet and a rubber sheet. 3. A solid polymer electrolyte fuel cell comprising the electrolyte membrane / electrode assembly according to claim 1 sandwiched between separators. 4. The solid polymer electrolyte fuel cell according to claim 3, wherein a region near the edge of the main surface of the separator in contact with the electrolyte membrane / electrode assembly is the solid polymer electrolyte membrane / insulating film adhesive. A solid polymer electrolyte fuel cell, wherein the fuel cell is laminated directly in contact with an insulating film region of a sheet.