JPH03208260A - Manufacture of connecting body between solid high polymer electrolyte membrane and electrode - Google Patents

Abstract

PURPOSE:To increase the reaction efficiency and to realize a high output by connecting a solid high polymer electrolyte membrane and a gas diffusion electrode in the condition to permeate in the reaction membrane of the gas diffusion electrode. CONSTITUTION:Hydrophile reaction membranes 3A and 3B are formed at the ratio 0.7:7:3 of platinum of the mean particle diameter 50Angstrom , a hydrophile carbon black of the mean particle diameter 450Angstrom , and polytetrafluoroethylene of the mean particle diameter 0.3mum, and hydrophobic gas diffusion membranes 4A and 4B are formed at the ratio 7:3 of a hydrophobic carbon black of the mean particle diameter 420Angstrom and polytetrafluoroethylene of the mean particle diameter 0.3mum. The reaction membranes 3 and the diffusion membranes 4 are superposed and rolled, and Pt 0.56mg/cm<2> is held to the reaction membrane 3 side in the hydrogen chloroplatinate oxidization and reduction method to make into gas diffusion electrodes 2A and 2B. To the reaction membrane side of the electrodes 2, an alcohol solution of perfluorosulfuric acid polymer is spread. Two sheets of such gas diffusion electrodes 2 are connected at the reaction membrane sides, and a hot press is applied in the condition at 120 to 130 deg.C and 60kg/cm<2> to make a connecting body. In such a way, the area the catalyst reaction is generated is increased, the adhesive strength is increased, and the moving resistance of H<+> can be reduced.

Description

[Detailed Description of the Invention] Industrial Application Fields The present invention relates to a method for producing an assembly of a solid polymer electrolyte and an electrode, and when the assembly is used in a fuel cell, water electrolysis, etc. It was devised to improve the efficiency of the battery reaction.

Conventional technology> Fuel cells do not require the use of fossil fuels, which have resource depletion, and have the advantages of generating almost no noise and being able to recover energy much more efficiently than other energy engines. Because of these characteristics, it is used as a relatively small power generation plant for each building or factory, for example.

In recent years, it has been considered that fuel cells can be used as a power source for a motor that operates in place of an internal combustion engine in a vehicle, and that the motor can drive a vehicle or the like. What is important in this case is that it is natural to reuse the substances produced by the reaction as much as possible, and as it is clear from the fact that it is used in automobiles, a large output is not required, but all It is desirable that the equipment be as small as possible, and from this point of view, solid polymer electrolyte fuel cells are attracting attention.

Here, as an example, the basic structure of a solid polymer electrolyte fuel cell main body will be explained with reference to FIG. 3. As shown in the figure, the battery main body 01 is constructed by joining gas diffusion electrodes 03A and 03B to both sides of a solid polymer electrolyte membrane 02. This assembled body is manufactured by placing gas diffusion electrodes 03A and 03B on both sides of solid polymer electrolyte membrane 02, and then hot-pressing or the like. Further, gas diffusion electrodes 03A and 03B are connected to reaction films 04A and 03B, respectively.
4B and gas diffusion membranes 05A, 05B are joined, and the surfaces of the reaction membranes 04A, 04B are in contact with the electrolyte membrane 02. Therefore, the battery reaction is mainly caused by the electrolyte membrane 0
2 and reaction 111104A, 04B.

For example, gas diffusion electrode 03A is an oxygen electrode, gas diffusion electrode 03
When B is used as a hydrogen electrode and oxygen and hydrogen are supplied to the reaction membranes 04A and 04B through gas diffusion #05A and 05B, the following reaction occurs at the interface between each reaction membrane 04A and 04B and the electrolyte membrane 02. happens.

Interface of reaction membrane 04A: 0 + 4 H"+4 e -2 HO Interface of reaction membrane 04B: 2H-=4H"+4e Here, 4g flows from the hydrogen electrode to the oxygen electrode through the electrolyte membrane 02, but 4e flows from the hydrogen electrode to the oxygen electrode through the load 06, and electrical energy is obtained.

Problems to be Solved by the Invention In the fuel cell main body 01 having the above-described configuration, the cell reaction mainly occurs at the contact surface between the electrolyte membrane 02 and each reaction membrane 04A, 04B, so in order to improve the cell performance, There is a problem in that the electrode itself must be made larger.

That is, for example, in order to pursue miniaturization of fuel cells, it is essential to improve the cell reaction per unit volume of the cell body 01 described above. This also applies when water electrolysis or the like is performed.

In view of these circumstances, an object of the present invention is to provide a method for producing an assembly of a solid polymer electrolyte membrane and an electrode, which greatly improves cell reaction efficiency when used in fuel cells, water electrolysis, etc. shall be.

<Means for Solving the Problems> A method for producing an assembly of a solid polymer electrolyte membrane and an electrode according to the present invention that achieves the above-mentioned object includes a reaction membrane and a gas diffusion membrane on both sides of a solid polymer electrolyte membrane. When manufacturing a bonded body made by bonding the reaction membrane sides of two gas diffusion electrodes,
The method is characterized in that the solution of the solid polymer electrolyte is applied to at least one of the gas diffusion electrodes and then hot pressed.

In the present invention, the solid polymer electrolyte refers to an electrolyte that does not become liquid even in the presence of water, such as perfluorosulfonic acid polymer (nafion: *product name). In addition, in order to make a solid polymer electrolyte into a solution, it is necessary to dissolve the solid polymer electrolyte and use a solvent that can be removed by evaporation during hot pressing. Such solvents include, for example, methanol, ethanol, isopropylene Mention may be made of alcohols such as beer alcohol.

Here, the concentration of the solution is not particularly limited as long as there is no problem in coating workability and a solid polymer electrolyte membrane is formed over the entire area after hot pressing. In addition, from the point of view of improving reaction efficiency, it is desirable that the solid polymer electrolyte membrane be thinner, as will be described later, and therefore, it is preferable to make the concentration of the solution as thin as possible. Of course, the premise is that it has the original function, ie, gas barrier properties.

In the present invention, a solid polymer electrolyte solution is applied to the gas diffusion electrode, but the application method is not particularly limited, and any method that can be applied almost uniformly over the entire surface of the gas diffusion electrode may be used. . As will be described later, in order to increase the reaction efficiency by permeating the solution into the reaction membrane of the gas diffusion electrode, it is preferable to apply the solution while suctioning it from the opposite side of the gas diffusion electrode. Preferably, there are two gas diffusion electrodes.

Further, hot pressing after coating is not particularly limited as long as the solvent of the solid polymer electrolyte solution is evaporated and the two gas diffusion electrodes are bonded via the solid polymer electrolyte membrane.

The gas diffusion electrode may be a conventionally known electrode, such as one formed by bonding a reaction membrane and a gas diffusion membrane (for example, see Japanese Patent Laid-Open No. 154571/1983). here,
The reaction membrane is generally made of a catalyst made of platinum metal and/or its oxide, or an alloy of Pt, Pd, and/or Ir with Ru, Sn, etc., or hydrophilic carbon particles supporting the catalyst. is dispersed in fluororesin or the like.

According to the method of the present invention, the reaction membrane of the gas diffusion electrolyte is hot-pressed in a state in which the solid polymer electrolyte solution has penetrated, so the contact area between the catalyst dispersed in the reaction membrane and the solid polymer electrolyte membrane is large. Become. In addition, since the solution is applied and then hot pressed to form a solid polymer electrolyte membrane, it is possible to firmly bond through an extremely thin membrane.
The movement resistance of is reduced. For these reasons, when the assembled body produced by the method of the present invention is used in fuel cells, water electrolysis, etc.,
The efficiency of the battery reaction is significantly improved.

Practical example Hereinafter, the present invention will be explained based on examples.

A hydrophilic reaction membrane consisting of platinum with an average particle size of 50 μm, hydrophilic carbon black with an average particle size of 450 μm, and polytetrafluoroethylene with an average particle size of 0.3μ in a ratio of 0.7:7:3; Hydrophobic carbon black with a particle size of 420 people and bolite trouble oleoethylene with an average particle size of 0.3μ are 7:
A gas diffusion electrode (thickness: 0.6 m) was manufactured, which consisted of a hydrophobic gas diffusion membrane having a ratio of 1.3 to 3. Here, the hydrophilic reaction membrane and the hydrophobic gas diffusion membrane can be obtained by mixing raw material powders other than platinum with solvent naphtha, alcohol, water, hydrocarbon, etc., and then compression molding the mixture. Then, these are piled up and rolled, and PtO. 56IIIg/
By supporting /clI, it was made into a gas diffusion electron.

An alcohol solution of a barfluorosulfonic acid polymer (Nafion 117, manufactured by DuPont) was applied to the reaction membrane side of the gas diffusion electrode. This coating is done by placing the gas diffusion layer on a vacuum plate and at a temperature of 70℃! ! This was done while suctioning from the side, and the coating amount was 0.6 g/cd (impregnation depth was 40 to 50 μm).

Prepare two gas diffusion electrodes coated in this way, put the reaction membrane sides together, and heat them for 60k at 120-130℃ for 60 seconds.
A conjugate was obtained by hot pressing under the conditions of g/cII.

The thus manufactured assembled body was sandwiched between two gas separators and a power generation test was conducted.

FIG. 1 conceptually shows this state.

In FIG. 1, 1 is a solid polymer electrolyte membrane, 2A and 2B are gas diffusion electrodes, and the gas diffusion electrodes 2A and 2B are respectively composed of reaction membranes 3A and 3B and gas diffusion membranes 4A and 4B. Note that the area where the solid polymer electrolyte solution permeated into the reaction membranes 3A and 3B and became the solid polymer electrolyte membrane 1 is shown with diagonal lines. Further, 5 and 6 are gas separators. The gas separator 5 alternately has hydrogen supply grooves 5a for supplying hydrogen to two gas diffusion electrodes serving as hydrogen electrodes, and cooling water supply grooves 5b for flowing cooling water to cool the two gas diffusion electrodes. The gas separator 6 has an oxygen supply groove 6a for supplying oxygen to the gas diffusion electrode 2B serving as an oxygen electrode.

In such a configuration, a power generation test was conducted by supplying hydrogen and cooling water to the gas separator 5 and supplying oxygen to the gas separator 6. In addition, oxygen has a gas pressure of 1 kg/
cjG, flow rate 2. 6 1/win, hydrogen gas pressure was 0.4 kg/c+/G, flow rate was 2.01/win, and cooling water temperature was 70°C. In addition, gas diffusion electrodes 2A, 2
The effective area of B was 12×12 cm.

For comparison, the above example was used, except that a bonded body in which gas diffusion electrodes similar to those described above were bonded by pot press to both sides of a solid polymer electrolyte membrane made of Nafion 117 (manufactured by DuPont) with a thickness of 0.17 m was used. A power generation test was conducted in the same manner.

These results are shown in FIG. As is clear from these results, when the conjugate according to the method of the present invention was used, the efficiency of the cell reaction was improved and the output was increased.

Effects of the Invention> As explained above, according to the method of the present invention, the solid polymer electrolyte membrane and the gas diffusion electrode are joined in a state where the reaction membrane of the gas diffusion electrode is penetrated, so the area where the catalytic reaction occurs is increased. At the same time, the adhesive force increases, and by making the solid polymer electrolyte membrane thinner, the movement resistance of H1 can be reduced. Therefore, when the conjugate produced by the method of the present invention is used in fuel cells, water electrolysis, etc., the reaction efficiency increases and output is increased.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing an embodiment of the present invention, FIG. 2 is a graph showing the results of a power generation test, and FIG. 3 is a conceptual diagram showing a solid polymer electrolyte membrane fuel cell according to the prior art. In the drawing, 1 is a solid polymer electrolyte membrane, 2A and 2B are gas diffusion electrodes, 3A and 3B are reaction membranes, 4A and 4B are gas diffusion membranes, 5 and 6 are gas separators, 5m is a hydrogen supply groove, and 5b is a cooling The water supply groove 6a is an oxygen supply groove. 1 2A, 2B 3A, 3B 4A, 4B 5, 6 5a 5b 6a Solid polymer electrolyte membrane Gas diffusion electrode Reaction membrane Gas diffusion membrane Gas separator Hydrogen supply prisoner cooling water supply IK Oxygen supply groove 3 Figure 1 page Continuation @ Inventor Hiroshi Nakajima @ Inventor Fuyuki Takeuchi? 4-chome, Kannon-Shinmachi, Nishi-ku, Hiroshima City, Prefecture 6-4-chome, Kannon-Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture ■6-22, 6-22, Hiroshima Research Institute Mitsubishi Heavy Industries, Ltd. Mitsubishi Heavy Industries, Ltd.

Claims (2)

[Claims] (1) When producing a bonded body in which the reaction membrane sides of two gas diffusion electrodes each consisting of a reaction membrane and a gas diffusion membrane are joined to both sides of a solid polymer electrolyte membrane, at least one of the gas diffusion electrodes is A method for producing an assembly of a solid polymer electrolyte membrane and an electrode, the method comprising applying a solution of the solid polymer electrolyte to the surface and then hot pressing. (2) The method for producing an assembly of a solid polymer electrolyte membrane and an electrode according to claim 1, wherein the solid polymer electrolyte is a perfluorosulfonic acid polymer and an alcohol solution thereof is used.