JPH0832963B2 - Ion-exchange membrane-electrode assembly manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an ion exchange membrane-electrode assembly used in various electrochemical devices using an ion exchange membrane as a solid electrolyte.

[Conventional technology]

Electrochemical devices that use an ion exchange membrane as a solid electrolyte include water electrolyzers, alkali halide electrolyzers, fuel cells, oxygen separators, hydrogen separators, and the like. In these devices, an ion-exchange membrane with electrodes integrally bonded is generally used.

Conventionally, as a method for producing an ion exchange membrane-electrode assembly, a method in which a catalyst electrode composed of a mixture of an electrode material powder and a binder is thermocompression-bonded to the ion exchange membrane (for example, JP-B-58-15544).
(Japanese Laid-Open Patent Publication No. 2003-242242) and the electroless plating method are known.

Furthermore, if the electroless plating method is classified, Japanese Patent Publication No. 56-36873
A method called an infiltration method in which a metal salt solution and a reducing agent solution are placed across an ion exchange membrane and a reducing agent is allowed to permeate the ion exchange membrane to form a metal layer on the metal salt solution side membrane. A metal ion belonging to the platinum group is ion-exchanged and adsorbed on the ion-exchange membrane, and then treated with an aqueous solution of borohydride to deposit a metal layer on the surface of the membrane to subsequently form a mixed solution of the metal salt and the reducing agent. There is a method called an adsorption reduction growth method in which a metal layer on the film surface is grown by immersion.

[Problems to be Solved by the Invention]

The properties required for the ion exchange membrane-electrode assembly used in the electrochemical device are low electrical resistance, the metal layer bonded to the ion exchange membrane has flexibility, and the ion exchange membrane. The adhesiveness between the metal layer and the metal layer is good, the metal layer is not peeled off when the bonded body is used, and the durability is excellent, and the operation and process for manufacturing the bonded body are simple. However, it is desired that the time is short.

Although there are demands as described above, the permeation method is simple in operation and process, and although the time is short, a metal layer having a non-uniform thickness is formed on the ion exchange membrane, and the adhesiveness between the ion exchange membrane and the metal layer is high. It is only possible to obtain a bonded body having a weak electric resistance and a large electric resistance. On the other hand, the adsorptive reduction growth method has a smaller electric resistance and better adhesiveness than the joined body obtained by the permeation method, but uses a mixed solution of a metal salt and a reducing agent to grow a metal layer. Therefore, it is necessary to pay close attention to the preparation and management of the matt valley, and it is difficult to increase the matt speed so as not to lose the stability of the matt bath.

[Means for solving the problem]

As a result of intensive studies by the present inventors, the problem of the above-mentioned infiltration method is that the nucleation for metal precipitation growth is non-uniform, and the adhesiveness progresses poorly, and the problem of the above adsorption-reduction growth method. The point is that as long as a metal salt and a reducing agent are used as a mixture, no fundamental solution can be seen, and the growth of the metal layer by the mixed solution of the metal salt and the reducing agent in the adsorption reduction growth method is eliminated. , A metal salt and a reducing agent are newly placed to separate the ion exchange membrane to grow a metal layer, and a bonded body with low electric resistance and excellent flexibility, adhesiveness and durability is produced. It was found that a method that can easily change the plating speed can be provided without preparing and managing the bath.

The present invention has been completed based on the above findings, and (1) The surface of the ion exchange membrane is obtained by ion-exchange adsorbing a metal ion on one surface of the ion exchange membrane, and then reducing the metal ion with a reducing agent. After depositing a thin metal layer inside, a metal salt solution is placed on the thin metal layer surface across the ion exchange membrane,
A method for producing an ion exchange membrane-electrode assembly, which comprises permeating a reducing agent solution from the opposite surface of the metal thin layer to deposit the metal layer on the metal thin layer, and (2) both sides of the ion exchange membrane After the metal ion is adsorbed on the surface of the ion-exchange membrane and the metal ion is reduced with a reducing agent to deposit a thin metal layer on the surface of the ion-exchange membrane, one metal thin-layer surface is sandwiched across the ion-exchange membrane. An ion-exchange membrane-electrode assembly characterized in that a metal salt solution is placed on the metal thin layer surface, and a reducing agent solution is permeated from the opposite surface to deposit a metal layer on the metal thin layer surface. Is a manufacturing method.

Examples of the ion exchange membrane used in the present invention include a cation exchange membrane having a sulfone group, a carboxyl group or a phosphon group, or an anion exchange membrane having each amine group, quaternary ammonium or sulfonium group.

Examples of the metal ion to be ion-exchanged and adsorbed in the present invention include an ammine complex ion or a halogen complex ion, and as a reducing agent for the ion-exchanged and adsorbed metal ion, hydrogen, hypophosphite, a borohydride compound or Examples include hydrazine.

Further, examples of the metal salt used in the present invention include chloride, sulfate, nitrate, perchlorate or chloroammonium salt, and the reducing agent for these metal salts includes
Examples include hypophosphite, borohydride compounds and hydrazine.

 Hereinafter, the present invention will be described in more detail with reference to Examples of the present invention.

Example 1 An ion exchange membrane 4 (trade name: Nafion 117, manufactured by Dyupon Co., Ltd.) was fixed to an L-shaped holder having an inner diameter of 16 mm shown in FIG. The L-shaped holder is composed of acrylic resin frames 1a and 1b, packings 2a and 2b, and tightening metal fittings 3a and 3b, and the ion exchange membrane 4 is fixed to the central portion.

20 ml of a 0.2% aqueous solution of a platinum amine complex {Pt (NH ₃ ) ₄ Cl ₂ } was injected into the chamber A 5 of this holder from the injection port 7, left at 30 ° C. for 2 hours, drained of the residual liquid, and washed with water. Then set this to 0.
It was immersed in a 2% NaBH ₄ aqueous solution at 30 ° C. for 1 hour to reduce the platinum ammine complex ions captured in the ion exchange membrane 4 to deposit platinum on one side of the ion exchange membrane 4. Then, 3% H ₂ PtCl ₆ · 6H ₂ O aqueous solution was injected into chamber A 5, and 1% NaBH ₄ aqueous solution was injected into chamber B 6, and the mixture was immersed at 60 ° C for 15 minutes to a predetermined amount on the film surface on the side of chamber A 5. The metal layer of was deposited.

[Example 2] The same ion exchange membrane 4 as the L-shaped holder used in Example 1 was used.
And the platinum ammine complex {Pt (NH ₃ ) ₄ C from the inlets 7 and 8 into chambers A and 5 of the holder, respectively.
20 ml of a 0.2% aqueous solution of l ₂ } was injected, the mixture was allowed to stand at 30 ° C. for 2 hours, the residual liquid was discharged, and then washed with water. Next, this was immersed in a 0.2% NaBH ₄ aqueous solution at 30 ° C. for 1 hour to reduce the platinum ammine complex ions captured in the ion exchange membrane 4 to deposit platinum on both sides of the ion exchange membrane 4.

Subsequently, 3% H ₂ PtCl ₆ .6H ₂ O aqueous solution was placed in the chamber A 5, and the chamber B 6
Inject 1% NaBH ₄ aqueous solution into the solution and immerse it at 60 ℃ for 15 minutes.
A predetermined amount of metal layer was deposited on the film surface on the chamber 5 side. Furthermore L
The mold holder is washed with water, 1% NaBH ₄ aqueous solution is poured into the chamber A, and 3% H ₂ PtCl ₆ .6H ₂ O aqueous solution is poured into the chamber B 6.
A metal layer was also deposited on the film surface on the chamber 6 side.

The ion exchange membrane-electrode assembly A obtained in Example 2 above, the ion exchange membrane-electrode assembly B obtained by bonding platinum to the ion exchange membrane by the permeation method, and the ion exchange by the adsorption reduction growth method. Ion exchange membrane obtained by bonding platinum to the membrane-Current when each electrode assembly C is used in a water electrolysis cell-
When the voltage characteristics were compared, the results shown in FIG. 2 were obtained. In FIG. 2, curves A, B and C show the current-voltage characteristics of the ion exchange membrane-electrode assemblies A, B and C, respectively.

In FIG. 2, the conjugate A obtained by the method of the present invention is superior to the conjugate B obtained by the permeation method, and exhibits a current-voltage characteristic comparable to that of the conjugate C obtained by the adsorption reduction growth method. Recognize.

〔The invention's effect〕

An ion-exchange membrane that exhibits excellent current-voltage characteristics without using a plating bath that requires preparation and control by the method of the present invention-
An electrode assembly can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an ion exchange membrane holder according to an embodiment of the present invention, and FIG. 2 shows an ion exchange membrane-electrode assembly obtained by the method of the present invention and the conventional permeation method and adsorption reduction growth method. It is a figure which shows the current-voltage characteristic at the time of using for a water electrolysis tank.

Claims (2)

[Claims] 1. A metal ion is ion-exchanged and adsorbed on one surface of an ion exchange membrane, and then the metal ion is reduced with a reducing agent to deposit a thin metal layer on the surface of the ion exchange membrane, and then the ion is adsorbed. An ion characterized in that a metal salt solution is placed on the surface of the thin metal layer across an exchange membrane, and a reducing agent solution is permeated from the opposite surface of the thin metal layer to deposit the metal layer on the thin metal layer. Method for manufacturing exchange membrane-electrode assembly. 2. A metal ion is adsorbed and adsorbed on both sides of the ion exchange membrane, and then the metal ion is reduced by a reducing agent to deposit a thin metal layer on the surface of the ion exchange membrane, and then the ion exchange is performed. The metal salt solution is placed on one metal thin layer surface across the membrane, and the reducing agent solution is permeated from the opposite surface to deposit the metal layer on the metal thin layer. A method for producing a featured ion exchange membrane-electrode assembly.