JPS6167787A - Production of joined body of ion exchange resin film and electrode - Google Patents

Abstract

PURPOSE:To obtain a joined body exhibiting excellent electrochemical characteristics in a method for joining an electrode consisting of a mixture composed of electrode catalyst powder, ion exchange resin powder and binder to a titled film by specifying the materials and joining further the specific electrode thereto. CONSTITUTION:The mixture composed of the electrode catalyst powder, an org. solvent soln. of the ion exchange resin consisting essentially of a perfluorocarbon resin or the mixed solvent soln. composed of the org. solvent and water thereof and the fluororesin binder is prepd. A mixed electrode- electrolyte body layer consisting of the mixture composed of the catalyst powder, ion exchange resin and binder in said mixture is formed with the mixture as a starting material to one or both surfaces of an ion exchange membrane consisting essentially of the perfluorocarbon resin. The electrode consisting of the mixture composed of the electrode catalyst powder and fluororesin binder is further joined to said mixed body layer, by which the intended joined body is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing an ion exchange resin membrane-electrode assembly. More specifically, the present invention is applicable to various electric devices such as fuel cells, water electrolyzers, salt electrolyzers, hydrochloric acid electrolyzers, electrochemical oxygen separation equipment, electrochemical hydrogen separation equipment, and water electrolysis type humidity sensors. The present invention relates to a method for manufacturing an ion exchange resin membrane-electrode assembly used in chemical equipment.

Conventional technology Electrochemical devices in which an ion exchange resin membrane is combined with a solid electrolyte and electrodes are integrally bonded to the membrane have already been developed, such as fuel cells (for example, US Pat. No. 3,134,607), water electrolysis 4FF (for example, J, S, Bone, Proceedi)
ngs of141h Δannual Power
5 sources Conference
.

p62-G4 (1960)), halide electrolytic cells (e.g., JP-A-54-1074-3), electrochemical oxygen minute equipment (e.g., JP-A-43-25001,
Or Special Publication No. 5B-3397!11), electrochemical hydrogen separation system (e.g. 5tanley l-1,
nger and Robert G, l-la
l-1alde, 3ciencc, Vol.
142. No. 3587 (1963)) and water electrolysis type humidity sensors (e.g. Keiyasu Takenaka.

Shima Yoei-9 Yoji Kawami, 1st Leeryojutsu, Vol. 4
No.

5 (1984)) have been proposed.

Ion exchange) I11 lipid membranes were once made of styrene/divinylbenzene resin as a core and introduced with ion exchange groups, but in recent years, sulfonate resins have been used. 119 i4, carbon? Perfluorocarbon resins containing 1% 7g of IM or 1% ion exchange are now commonly used because of their excellent properties. Ion exchangers are used in fuel cells. Alternatively, in a water electrolysis tank, a promean type b type is used, and in a salt electrolyzer, a two type Δn type is used.

A method for integrally bonding an electrode to an ion-exchange resin membrane is to heat and press a mixture of electrode catalyst powder and a fluororesin as a binder to the ion-exchange resin membrane (for example, US Pat. 8-154i
44''1-3) and a method of electroless plating of an electrode catalyst metal onto an ion exchange resin membrane (for example, Japanese Patent Application Laid-Open No. 55-38934
53,).

Electrodes vary depending on the type of electrochemical device, but 7
They can be classified into gas diffusion electrodes and gas generation electrodes.In the case of gas diffusion electrodes, a reactive gas is supplied to the electrode, and in the case of gas generation electrodes, the gas is supplied to the electrode by an electrolytic reaction. It is generated from the electrode.

Gas diffusion electrodes are used as cathodes in fuel cells, electrochemical oxygen classification devices, anodes in electrochemical hydrogen separation devices, and cathodes in halide electrolysers when oxygen is introduced into l12 depolarizers. The gas generating electrode is used as an anode of a water electrolyzer, an electrochemical oxygen valve 11lII device, a cathode of an electrochemical hydrogen separation device, an anode of a halide electrolyzer, etc.

In general, among the methods for integrally bonding electrodes to the ion exchange resin membrane (e) above, the heat compression method can be applied to both the gas expansion electrode and the gas generation electrode, but the electroless plating method can be applied to both the gas expansion electrode and the gas generation electrode. Just apply one or more to the electrode. In the case of a gas generation electrode, it does not matter if the electrode's reaction sites 1 to 1 get wet with water, but on the platform of a gas diffusion electrode, there are parts that get wet with water and parts that do not get wet with water. This is because the reaction will not proceed successfully without it. In other words, the heat compression method (
) The water repellency of the fluororesin as a binder effectively contributes to the gas diffusion electrode reaction.

An electrochemical reaction occurs at the interface between an electrode and an electrolyte, and the current-voltage characteristics of the electrochemical reaction are greatly influenced by the contact area between the electrode and the electrolyte. When the electrolyte is an aqueous solution, the contact area between the electrode and the electrolyte is generally large; however, when the electrolyte is a solid electrolyte such as an ion exchange resin membrane, the contact area between the electrode and the electrolyte is relatively large. small. One way to improve this problem is, for example,
As described in No. 14220, a layer of a mixture of an electrode catalyst powder, an ion exchange resin powder, and a binder is interposed between an ion exchange resin membrane as a solid electrolyte and an electrode,
There is a way d1 to increase the contact area between the solid electrolyte and the electrode.

Problems that the invention seeks to solve1 The method of increasing the bonding area between the ion exchange resin membrane and the electrode described in Japanese Patent Publication No. 111220/1982 is extremely effective as a basic concept. .

However, there was a problem with t, 1%"l, which was adopted here, and there was a limit to the performance of an electrochemical device using an assembly of an ion exchange resin membrane and an electrode. Since styrene-divinylbenzene Jirfi is used in which sulfonic acid groups are introduced using ion-exchange resin powder, there are problems with heat resistance and chemical stability.Also, electrode catalyst powder and ion-exchange resin powder A sulfonated styrene-divinylbenzene copolymer is used as a powder material in the mixture layer of the sulfonated styrene-divinylbenzene, but this material is also heat resistant.
It has advantages in terms of strength and chemical stability. Particularly, when this material r1 is used for an anode, the anodic oxidation resistance has an FI of 1 point. In addition, since the particle size of the powder is 200 mesh, the number of contact points between the electrode catalyst powder and the electrolyte does not increase so much. Furthermore, the trichlorethylene solution of borisdyrene used as a binder has insufficient water repellency and coats the electrode catalyst surface and the ion exchange resin powder surface in a film-like manner, so that it is virtually impossible to separate the electrode catalyst powder. It is not expected that the contact area with the ion exchange resin powder will increase much.

Means for Solving the Problems The present invention provides an ion-exchange resin membrane having a perfluorocarbon resin as a base, and an electrode catalyst layer on one or both sides of the ion exchange resin membrane. An electrode-electrolyte mixture layer is formed using as a starting material a solution of an ion-exchange resin in a 41-mer solvent or a mixed solution of an organic solvent and water, and a mixture of a fluororesin binder, and an electrode-electrolyte mixture layer is formed on top of the electrode-electrolyte mixture layer. The above-mentioned problem can be solved by forming an electrode made of a mixture with a fluororesin.

Operation The greatest feature of the present invention is that the amount of ion exchanger 1 negative resin to be mixed into the electrode-electrolyte mixture layer is
Pernol Δl':I NoJ-bon resin 3'3. j4
．． The right side of the ion exchange resin (some solvent solution or T
The point is that a mixture of solvent and water is used.

A typical ion exchange resin based on perfluorocarbon resin is perfluorocarbon sulfonic acid resin. The affinity of perful A locarbon sulfate resin to organic solvents varies depending on the number of moles of sulfate base, and this ion exchange resin has a large exchange capacity for lower aliphatic alcohols such as 11-butanol and other organic solvents. It is known to dissolve in highly polar organic solvents (Japanese Patent Publication No. 4B-13333).

Such a 4T ion exchange resin solution is manufactured by, for example, Aldrich Chemical Co., Ltd.
Nafion solution (NΔ"
It is sold under the name 1ON solution. Pufion solution is manufactured by Decobon Rei (DLI po) in the United States.
NΔFION, which is sold by N.t.
) is a 5% lower aliphatic alcohol (containing 10% water) solution of Perflu A rocarbon sulfonic acid resin (trade name).

When an ion exchange resin solution such as a Nafion solution, an electrode catalyst powder, and a fluororesin binder are mixed, contact points between the electrode catalyst powder and the ion exchange resin are formed in a very finely dispersed form. The contact area is much larger than when using an ion exchange resin like this.

In addition, ion exchange resins based on perfluorocarbon resins have better heat resistance and chemical stability compared to ion exchange resins based on styrene divinylbenzene polymers, such as those in the previous book. and has far superior anodic oxidation resistance.

As the ion exchange group of the ion exchange resin contained in the ion exchange resin solution, a mixture of a sulfone M group and a carboxylic acid group can be used.

The transfer ion of the ion exchange group can be of the proton type, helium ion type, potassium ion type, etc., and can be selected as appropriate depending on the electrochemical device used. Moreover, the tetraconversion from protons to other ions can be carried out after bonding the Ti electrode to the ion exchange resin membrane.

All conventionally known electrode catalyst powders can be used.

Examples of fluororesin binders include polytetrafluoroethylene,
One or a mixture of a tetrafluoroethylene-6)propylene copolymer, a tetrafluoroethylene non-ethylene copolymer, and a polytrifluoroethylene chloride may be used. Also, these fluororesins are in powder form.

A water W1 suspension or an organic solvent suspension is used. It is also effective to mix and disperse 1 J of powdered fluororesin into a suspension of fluororesin.

As the ion exchange resin membrane, sul7A acid is used.

A perfluorocarbon resin having a carboxylic acid group or a mixture thereof as an ion exchange group is preferable. The mobile ion may be appropriately selected from proton type, sodium ion type, potassium ion type, etc. depending on the electrochemical device to be used.

Electrode to ion exchange resin membrane -? Various methods can be applied to join the I2 solute mixture. The first method is to prepare a thin film sheet 1~ from a mixed dispersion of an electrode catalyst powder, an ion exchange resin solution, and a fluororesin binder, and then heat the film after evaporating the solvent and dispersion medium to form an ion exchange resin membrane. The second method is to spray the above-mentioned mixed dispersion onto the ion exchange resin membrane, volatilize the solvent and dispersion medium, and then heat press. Method 3 is 1. g) The mixed dispersion liquid of e) is screen printed on an ion exchange resin membrane and heated and pressed. However, the present invention is not limited to these methods. Conventionally known methods can also be used for joining the electrode to the electrode-electrolyte mixture layer.

In any case, since the ion exchange resin and rejuvenating agent used in the present invention are all fluorine-containing polymers, they not only have excellent heat resistance, chemical stability, and anodic oxidation resistance, but also have excellent heat resistance, chemical stability, and anodic oxidation resistance. The mutual bonding strength between each material included in the electrode, between the electrode-electrolyte mixture layer and the ion exchange resin membrane, and between the electrode-electrolyte mixture layer and the electrode is extremely high.

The method for producing an ion exchange resin membrane-electrode assembly of the present invention may be applied to both the cathode side and the anode side, or may be applied to only one side. That is, an electrode containing a conventional ion exchange resin may be bonded to either the cathode or the anode.

Example 1 A rhodium electrode was bonded to one side of Nafion 117, a perfluorocarbon sulfonic acid resin film manufactured by Acobon Rei, by electroless plating. Is the amount of rhodium supported 4mo/cn? And so.

Next, platinum black powder 1 as electrode 1f+1 medium powder
20 for 0g! Add 5% Nafion solution of I (manufactured by Aldridge Chemical Company, USA, perfluorocarbon sulfonic acid resin membrane mixed solvent solution) and 4 ml of 60% polytetrafluoroethylene aqueous suspension, and knead with J: Rolled.

Vacuum dried and produced an electrode-electrolyte mixture sheet with a thickness of 0.2 mm.

Next, this electrode-electrolyte mixture sheet containing platinum black was placed on the side of the ion exchange resin membrane to which the rhodium electrode was bonded, to which the rhodium electrode was not bonded, at a temperature of 100°C.
Pressed at a pressure of 200 K (1/c + δ. Finally, an electrode sheet obtained from a suspension of 4 ml of 60% polyethylene tetrafluoride water in 10 g of platinum black powder was placed on top of the electrode-electrolyte mixture. Pot pressed on top.

The ion exchange resin membrane-electrode assembly thus obtained becomes a component of an electrochemical oxygen separation device.

That is, the rhodium electrode of this bonded body is used as an anode, the electrode containing platinum black is used as a cathode, air is supplied to the cathode side, water is supplied to the anode side, and when direct current is applied to both electrodes, the anode side On the cathode side, 1 q of pure oxygen is added, and 1 q of gas from which oxygen has been removed from the air is added on the cathode side.

2. In Example 1, the anode side was also the same electrode as the cathode side.

Effects of the Invention The ion exchange resin membrane-electrode assembly obtained by 1q in Example 1 is designated as △, and Example 1? In +1, sulfonated styrene-divinylbenzene resin was used instead of Nafion solution)
A case where the bonded body using powder (particle size 54 microns) is B, and an electrode is formed only with platinum black and polytetrafluoroethylene without including an electrode-electrolyte mixture layer on the cathode side in Example 1. The bonded body was designated as C, and the current density-voltage characteristics of each as an electrochemical oxygen separation device were compared, and the results shown in FIG. 1 were obtained.

That is, it is clear that excellent characteristics are exhibited in the order of A>B>C. B shows better properties than C, and when an ion exchange resin is mixed on the cathode side,
This is because the number of points of contact between the electrode and the electrolyte increases, and the effective area of electrode action increases accordingly. The reason why Δ exhibits better characteristics than B is due to the presence of the ion-exchanged 1θ resin mixed into the electrode-electrolyte mixture layer on the cathode side. In other words, because the ion exchange resin powder with relatively large particles is used in the platform of B, there are not many contact points between the platinum black and the ion exchange resin powder, whereas in the case of Δ, the ion exchange resin powder This is simply because the contact area between the two is larger because they are in distributed contact with the platinum black in a much finer form.

Next, the ion exchange resin membrane-electrode assembly obtained in Example 2 was designated as D, and the assembly obtained in Example 2 using sulfonated styrene-divinylbenzene resin powder instead of the Nafion solution was designated as E. , were assembled into an electrochemical oxygen separator and subjected to a life test at a current density of 200 mΔ/-, and the relationship between operating time and voltage was 1q as shown in FIG. That is, in the case of the product of the present invention, no abnormality was observed, whereas in the case of the conventional product [the second platform], the voltage increased as the operating time progressed. This is due to the difference of 1 anodization + 11 of the ion exchange resin It? contained in the electrode-electrolyte mixture on the anode side.

(Edited above)! IiI! As shown, the present invention provides an ion exchange resin membrane-electrode assembly that exhibits excellent electrochemical properties and has an extremely high ITIi value.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention. The current density-voltage characteristics when the ion-exchange resin membrane-electrode assembly obtained in Example 1-1 is applied to electrochemical oxygen fractionation are compared with those of conventional products. Figure 2 shows a comparison of the change over time in the electric current F' when the ion exchange resin 11fi% electrode assembly according to one embodiment of the present invention is applied to electrochemical oxygen separation and loading with that of a conventional product. Δ, D...Product of the present invention, B, C, F... Conventional product AO Kuu Sardine k Totewa Koune Yamasho July (method) 1985 February 8 "1 1988 Special h' [Application No. 190333 2, Title of the invention, Full of ion exchange resin membrane-electrode assembly, Law 3, Name of the person making the amendment (7128) To Makoto Nasu, representative of the founder of Honbattery Co., Ltd., 1[ 7 , Contents of the amendment (1) Book 1, page 2, lines 10-12 [(e.g. J,
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Claims (1)

[Claims] 1. On one or both sides of an ion exchange resin membrane based on perfluorocarbon resin, apply an electrode catalyst powder, an organic solvent of an ion exchange resin based on perfluorocarbon resin, or a mixed solvent solution of an organic solvent and water, and a fluororesin bond. Using the mixture with the adhesive as a starting material, an electrode-electrolyte mixture layer consisting of a mixture of an electrode catalyst powder, an ion exchange resin based on a perfluorocarbon resin, and a fluororesin binder is formed, and the electrode-electrolyte is further A method for producing an ion exchange resin membrane-electrode assembly, which comprises joining an electrode made of a mixture of electrode catalyst powder and a fluororesin binder to a mixture layer.