JP2781630B2 - Method for activating a joined body of a solid polymer electrolyte membrane and an electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for activating a joined body of a solid polymer electrolyte membrane and an electrode, wherein the joined body is used for a fuel cell, water electrolysis, or the like. In this way, the efficiency of the battery reaction is improved.

<Conventional technology> Fuel cells do not require the use of fossil fuels, which have the problem of resource depletion, generate little noise, and have extremely high energy recovery efficiency compared to other energy engines. Because of this feature, it is used as a relatively small power plant, for example, in buildings or factories.

In recent years, it has been considered that this fuel cell is used as a power source of a motor that operates instead of an internal combustion engine mounted on a vehicle, and a vehicle or the like is driven by the motor. In this case, it is important to recycle the substances generated by the reaction as much as possible.
It is desirable that all the incidental equipment be as small as possible, and in view of this, a solid polymer electrolyte fuel cell is receiving attention.

Here, as an example, the basic structure of the polymer electrolyte fuel cell main body will be described with reference to FIG. As shown in the figure, the battery main body 01 is configured by joining gas diffusion electrodes 03A and 03B to both sides of a solid polymer electrolyte membrane 02. The joined body is manufactured by, for example, hot-pressing the gas diffusion electrodes 03A and 03B on both sides of the solid polymer electrolyte membrane 02. In addition, gas diffusion electrodes 03A, 03
B is formed by bonding reaction films 04A and 04B and gas diffusion films 05A and 05B, respectively, and the surfaces of the reaction films 04A and 04B are in contact with the electrolyte membrane 02. Therefore, the battery reaction mainly occurs at the contact surface between the electrolyte membrane 02 and the reaction membranes 04A and 04B.

For example, the gas diffusion electrode 03A is an oxygen electrode, the gas diffusion electrode 03B is a hydrogen electrode, and oxygen and oxygen are passed through the respective gas diffusion films 05A and 05B.
When hydrogen is supplied to the reaction films 04A and 04B, each of the reaction films 04A and 04B
The following reaction occurs at the interface between the electrolyte and the electrolyte membrane 02.

Interface of the reaction film 04A: O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O Interface of the reaction film 04B: 2H ₂ → 4H ⁺ + 4e ^- Here, 4H ⁺ flows from the hydrogen electrode to the oxygen electrode through the electrolyte membrane 02, 4e ^- is will flow from the hydrogen electrode to the oxygen electrode through the load 06, 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 of the reaction membranes 04A and 04B. There is a problem that the electrode itself must be enlarged.

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

In view of such circumstances, the present invention provides a method for activating a joined body of a solid polymer electrolyte membrane and an electrode, which greatly improves the reaction efficiency of a cell when used in a fuel cell, water electrolysis, or the like. With the goal.

<Means for Solving the Problems> A method for activating a joined body of a solid polymer electrolyte membrane and an electrode according to the present invention, which achieves the above object, comprises two gas diffusion layers each comprising a reaction membrane and a gas diffusion membrane. A bonded body obtained by bonding the reaction membrane side of the electrode to both sides of the solid polymer electrolyte membrane is heated in a temperature range of 130 ° C. or more of the glass transition temperature of the solid polymer electrolyte membrane and 270 ° C. or less of its decomposition temperature. Processing.

In the present invention, the gas diffusion electrode refers to one formed by joining a reaction film and a gas diffusion film, and may be a conventionally known one (for example, JP-A-62-154571). here,
In general, the reaction film is made of, for example, platinum metal and / or its oxide, a catalyst made of Pt, Pd and / or Ir, etc. alloyed with Ru, Sn, or the like, or a hydrophilic catalyst carrying such a catalyst. Carbon fine particles are dispersed in a fluororesin or the like.

Further, in the present invention, the solid polymer electrolyte membrane refers to an electrolyte that does not become a liquid even when water is present, and includes, for example, a perfluorosulfonic acid polymer membrane (Nafion: trade name).

In the present invention, such a joined body of the gas diffusion electrode and the solid polymer electrolyte membrane is subjected to a heat treatment at a temperature of 130 ° C. or higher and a decomposition temperature of 270 ° C. or lower of the glass transition temperature of the solid polymer electrolyte membrane. . Thereby, activation of the joined body can be achieved. For example, when the joined body is used for a fuel cell, electrolysis, or the like, there is an effect that a cell reaction efficiency is improved.

It is not clear why the joined body is activated in this way, but the contaminated catalyst is activated during the manufacturing process of the joined body, the water repellent substance in the electrode is stabilized, and the projecting holes are cleaned. The reason is considered.

The heat treatment of the present invention is not particularly limited as long as the above-described effects are exerted at a temperature in the above range, for example, when a perfluorosulfonic acid polymer membrane is used as the solid polymer electrolyte membrane. In this case, the treatment may be performed at 130 to 280 ° C. for, for example, about 30 to 60 minutes, as is clear from the test examples described later.

<Example> Hereinafter, the present invention will be described based on examples.

On the reaction film side of a gas diffusion electrode (thickness 0.6 mm) composed of a hydrophilic reaction film composed of hydrophilic carbon black and polytetrafluoroethylene and a hydrophobic gas diffusion film composed of hydrophobic carbon black and polytetrafluoroethylene Then, Pt 0.56 mg / cm ² was supported by a platinum chloride redox method.

A 0.17 mm-thick perfluorosulfonic acid polymer film (Nafion: manufactured by DuPont) is sandwiched between such two gas diffusion electrodes, and hot-pressed at 120 to 130 ° C. for 60 seconds at 60 kg / cm ^2. Then, a joined body was obtained.

Then, the joined body is heated at 100 ° C, 150 ° C, 200 ° C, 250 ° C and 3 ° C.
Heat treatment was performed at 00 ° C. for 30 minutes and at 150 ° C., 200 ° C., and 250 ° C. for 60 minutes.

Each of the joined bodies thus manufactured was sandwiched between two gas separators, and a power generation test was performed. FIG. 1 conceptually shows the state.

In FIG. 1, 1 is a solid polymer electrolyte membrane, 2A and 2B are gas diffusion electrodes, and gas diffusion electrodes 2A and 2B are reaction membranes 3A and 3A, respectively.
3B and gas diffusion films 4A and 4B. Reference numerals 5 and 6 denote gas separators. The gas separator 5 has a hydrogen supply groove 5a for supplying hydrogen to the gas diffusion electrode 2A serving as a hydrogen electrode and a cooling water supply groove 5b for flowing cooling water for cooling the gas diffusion electrode 2A.
The gas separator 6 has an oxygen supply groove 6a for supplying oxygen to the gas diffusion electrode 2B serving as an oxygen electrode.
have.

In such a configuration, a power generation test was performed by supplying hydrogen and cooling water to the gas separator 5 and supplying oxygen to the gas separator 6. The oxygen gas pressure is 1kg / cm
² G, flow rate 2.6 l / min, hydrogen gas pressure 0.4 kg / cm ² G, flow rate 2.0 l / mi
n and the cooling water temperature was 70 ° C. In addition, gas diffusion electrode 2
The effective area of A, 2B was 12 × 12cm.

For comparison, a power generation test was performed in the same manner as in the above example using a similar joined body without heat treatment.

These results are shown in FIG. As is clear from the results, when the joined body activated by the method of the present invention was used, there was an effect that the efficiency of the battery reaction was improved and the output was increased.

<Effects of the Invention> As described above, according to the method of the present invention, the assembly of the solid polymer electrolyte membrane and the gas diffusion electrode can be activated by heat treatment. When used for water electrolysis or the like, the effect of increasing the reaction efficiency and increasing the output is exhibited.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing one 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 conventional solid polymer electrolyte membrane fuel cell. In the drawing, 1 is a solid polymer electrolyte membrane, 2A and 2B are gas diffusion electrodes, 3A and 3B
Is a reaction film, 4A and 4B are gas diffusion films, 5 and 6 are gas separators,
5a is a hydrogen supply groove, 5b is a cooling water supply groove, and 6a is an oxygen supply groove.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hiroshi Nakajima 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory (72) Inventor Yoshiyuki Takeuchi 4-chome Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture No. 6-22 Mitsubishi Heavy Industries, Ltd. Hiroshima Laboratory (56) References JP-A-64-62489 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01M 4/86-4 / 96 H01M 8 / 02,8 / 10

Claims (1)

(57) [Claims] 1. A joined body obtained by joining the reaction membrane side of two gas diffusion electrodes comprising a reaction membrane and a gas diffusion membrane to both sides of a solid polymer electrolyte membrane, and forming a glass transition of the solid polymer electrolyte membrane. A method for activating a joined body of a solid polymer electrolyte membrane and an electrode, wherein a heat treatment is performed in a temperature range of 130 ° C. or more and a decomposition temperature of 270 ° C. or less.