JPH03208262A - 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 electric power by connecting a solid high polymer electrolyte membrane and a gas diffusion electrode in the condition to soften or solve the soild high polymer electrolyte membrane in alcohol. 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. They are superposed and rolled, and Pt 0.56mg/cm<2> is held at the hydrophile reaction membrane side in the hydrogen chloroplatinate oxidization and reduction method to make into gas diffusion electrodes 2A and 2B. A perfluorosulfuric acid polymer membrane of the thickness 0.17mm is held between two sheets of such diffusion electrodes 2, and a hot press is applied in a mixture solution of the ratio 1:1 of isopropyle alcohol and a pure water in the condition at 120 to 130 deg.C and 60kg/cm<2> to form a connecting body. In such a way, the connection is made easily, and the connecting body of a thin membrane thickness and a low movement resistance of H<+> can be obtained.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for manufacturing an assembly of a solid polymer electrolyte membrane and an electrode, and when the assembly is used in a fuel cell, water electrolysis, etc. This was devised to improve the efficiency of battery reactions.

Conventional technology> Fuel ponds do not require the use of fossil fuels, which have resource depletion issues, generate almost no noise, and have very high energy recovery efficiency compared to other energy engines. Because of their excellent characteristics, they are used as relatively small power generation plants for buildings and factories, for example.

In recent years, it has been considered to use this fuel cell as a power source for a motor that operates in place of an internal combustion engine in a vehicle, and to power a vehicle or the like using the motor. 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 for automotive use, although a large output is not required, It is desirable to be as small as possible, and from this point of view, solid polymer electrolyte membrane fuel cells are attracting attention.

Here, as an example, the basic structure of a solid polymer electrolyte membrane fuel cell main body will be explained with reference to FIG. 4. As shown in the figure, the battery main body 01 is constructed by joining gas diffusion electrodes o3A, 03B to both sides of a solid polymer electrolyte 1j02. 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. In addition, gas diffusion S poles 03A and 03B each have a reaction MU 4
A, 04B and gas diffusion $0 5 A. , 0 5
The electrolyte membrane 02 is the reaction membrane 0.
The surfaces of 4A and 04B are in contact. Therefore, the battery reaction mainly occurs at the contact surface between the electrolyte membrane 02 and the reaction membranes 04A and 04B.

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

Interface of reaction membrane 04A: 0 +4 H''+4 e -2 H 0 Interface of reaction membrane 04B: 2 H → 4 H +4 e Here, 4K flows from the hydrogen electrode to the oxygen electrode through the electrolyte membrane 02. , 4ei will flow from the hydrogen electrode to the oxygen electrode through the load 06, and electrical energy will be obtained.

<Problems to be Solved by the Invention> In the fuel cell body 01 configured as described above, the cell reaction mainly occurs at the contact surface between the electrolyte WA02 and each reaction membrane 04A, 04B, so in order to improve the cell performance, it is necessary to There is an R title that requires making itself 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. Tozuru.

<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 is a method for manufacturing a solid polymer electrolyte membrane and electrode assembly according to the present invention, which consists of two gas diffusion electrodes each consisting of a reaction membrane and a gas diffusion membrane. The method is characterized in that the sandwiching body sandwiching the solid polymer electrolyte membrane on the reaction membrane side is heated and pressurized in a solvent to form a bonded body.

In the present invention, it refers to an electrolyte membrane that does not become liquid even when a solid polymer electrolyte membrane and carbon and water coexist, and an example thereof includes a perfluorosulfonic acid polymer membrane (Nafion: trade name).

On the other hand, 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, an alloy of Pt, Pd, and/or Ir, etc., or a hydrophilic carbon supporting a catalyst. It is made by dispersing mold particles in fluororesin, etc.

In the method of the present invention, a sandwich body in which a solid polymer electrolyte membrane is sandwiched between two gas diffusion electrodes is heated and pressurized (hot pressed) in a solvent to form a bonded body. Here, the term "solvent" refers to anything from pure organic solvents consisting of one or more organic solvents selected from alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, and organic solvents such as ethers to mixed solvents of organic solvents and water. For example, an alcohol aqueous solution prepared by adding 50% or more water to alcohol is suitable. In addition, as for the method of hot pressing in a solvent, it is possible to form a sandwiched body in the air and then immerse it in the solvent, or it is also possible to form a sandwiched body in a solvent. At this time, the solvent may be present at least around the clamping body.

Note that after bonding, it is necessary to remove the solvent and then form a bonded body.

According to the method of the present invention, the solid polymer electrolyte membrane softens or partially dissolves in the solvent, resulting in l! It will be in a moist state,
Bonding with the gas diffusion electrode becomes easy. Moreover, at this time, the solid polymer electrolyte membrane easily enters the reaction membrane of the gas diffusion electrode, increasing the area where the catalytic reaction occurs.
As a result, the solid polymer electrolyte membrane becomes extremely thin, resulting in the effect of lowering the resistance of ionic conduction.

Example of implementation Hereinafter, the present invention will be explained based on examples.

A hydrophilic reaction membrane consisting of platinum with an average particle size of 50, hydrophilic carbon black with an average particle size of 450, and polytetrafluoroethylene with an average particle size of 0.3μ in a ratio of 0,773, and a hydrophobic membrane with an average particle size of 420. carbon black and average particle size 0
．． A hydrophobic gas diffusion membrane consisting of a 7:3 ratio of 3μ polytetrafluoroethylene and a gas diffusion electrode (W-size: 0.6 wm) with an average particle size of 0.31 were manufactured.

Here, the hydrophilic reaction membrane and the hydrophobic gas diffusion membrane L can be obtained by mixing each raw material powder other than platinum with a solvent such as solvent naphtha, alcohol, water, or hydrocarbon, and then compression molding the mixture. Then, these are stacked and rolled, and a platinum chloride redox method is applied to the hydrophilic reaction membrane side.
o. ss. By supporting g/cIl, it was used as a gas diffusion electrode.

Between these two gas diffusion electrodes, 0.17+w[
barfluorosulfonic acid polymer membrane (Nafion:
(manufactured by DuPont) and hot pressed in a 1:1 mixture of isobrobyl alcohol and pure water at 120 to 130° C. for 60 seconds at 60 kg/cI17 to obtain a bonded body.

The hot press apparatus used in this example is shown in FIG. As shown in the figure, this apparatus ζ has an upper die 11 and a lower die 2, and an O-ring 13 is sandwiched between the upper die 11 and the lower die 12, so that the press chamber is isolated from the outside air. 14 can be formed, and the structure is such that a sandwiching body 15 sandwiching a solid polymer Ti desolate film between two gas diffusion electrodes is hot-pressed in this press chamber 14. The lower die 12 has an alcohol supply port communicating with the press chamber 13.
16 and an alcohol discharge passageway 7 are formed, through which the press chamber 14 can be filled with alcohol. On the other hand, above and below the upper mold 11 and the lower mold l2, these upper and lower molds 11.
Heaters 1.8, 19 are provided for heating 12. Further, a thirst sensor 20 is provided inside the upper mold 11.

To carry out hot pressing using such a device, an O-ring 13 is placed on the lower mold 12, and a clamping member 15 in which the solid polymer electrolyte membrane is sandwiched between two gas diffusion T4 electrodes is placed inside the O-ring 13. to put on snow.

After the upper mold 11 is assembled in this state, a mixture of isopropanol and pure water is supplied from the alcohol supply passage 16 until it is discharged from the alcohol discharge passage 17. Then, the press chamber 14 is pressurized while being heated to a set temperature while appropriately filling the press chamber 14 with alnil.

After heating, cooling water is poured into the press chamber 14 to lower the temperature of the press chamber 14, the jig is removed, and the bonded body is taken out. The above-mentioned bonded body is prepared by immersing this bonded body in a flow of pure water at about 100° C. and removing alcohol. Note that the method for removing alcohol is not particularly limited.
For example, it is possible to evaporate in a constant temperature chamber at 100° C. or lower in an N2 atmosphere.

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

FIG. 2 conceptually shows this state.

In FIG. 2, 1 is a solid polymer electrolyte membrane, 2A and 2B are gas diffusion electrodes, and the gas diffusion electrodes 2A and 2B are each composed of reaction 1[3A and 3B and gas diffusion membranes 4A and 4B.

In addition, 5 and 6 are gas barre evenings. The gas separator 5 has water T: a hydrogen supply groove 5a for supplying hydrogen to the two gas diffusion electrodes serving as poles, and a cooling water supply groove 5b for flowing cooling water to cool the two gas diffusion electrodes, alternately. The gas separator 6 has a gas diffusion electrode 2B serving as the m element electrode.
In this configuration, hydrogen and cooling water were supplied to the gas separator 5, and oxygen was also supplied to the gas separator 1 and 6 to conduct a power generation test. Ta. In addition, oxygen has a gas pressure of 1 kg/
cjG, flow rate 2. 6 / / win, hydrogen gas pressure o, akg7cic. , the FA amount was 2.01/llin, and the cooling water temperature was 1 to 70°C. In addition, the gas diffusion voltage gi
The effective area of i2A and 2B was 12×12em.

For comparison, a power generation test was conducted in the same manner as in the above example using the same bonded body as described above except that it was pressed in air instead of in a solvent.

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.

4. Effects of the Invention> As explained above, according to the method of the present invention, the solid polymer electrolyte membrane is bonded to the gas diffusion electrode in a state in which it is softened or dissolved in alcohol, so that bonding can be easily performed and the solid polymer electrolyte membrane can be easily bonded to the gas diffusion electrode. The polymer electrolyte membrane penetrates into the reaction membrane and the area where catalytic reactions occur due to contact increases, and the membrane itself becomes thinner, so the movement resistance (a) is 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 *,t diagram showing a device for carrying out an embodiment of the present invention, Fig. 2 is a conceptual diagram showing its test method, Fig. 3 is a graph showing the results of a power generation test, Fig. 4 1 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. , 3B are reaction membranes, 4A and 4B are gas diffusion membranes, 5 and 6 are gas separators, 5a is a hydrogen supply groove, 5b is a cooling water supply groove, 6a is an oxygen supply groove, 11 is an upper mold, 12 is a lower mold, 13 14 is an O-ring, 14 is a press chamber, 15 is a clamping body, 16 is an alcohol supply passage, 17 is an alcohol exhaust system, 18 and 19 are heaters, and 20 is a temperature sensor. Patent applicant Mitsubishi Heavy Industries, Ltd. Agent

Claims (1)

[Claims] It is characterized by forming a bonded body by heating and pressurizing a sandwiching body that sandwiches a solid polymer electrolyte membrane on the reaction membrane side of two gas diffusion electrodes consisting of a reaction membrane and a gas diffusion membrane in a solvent. A method for producing an assembly of a solid polymer electrolyte membrane and an electrode.