JPH06342666A - Solid high molecular type fuel cell - Google Patents

Abstract

PURPOSE:To provide a solid high molecular fuel cell, of which output performance is improved remarkably. CONSTITUTION:An ion exchange membrane, which is made of the composition of fluorine-retaining high molecular component having functional group and the fluorine-retaining compound core material at 70-95% of hole factor before the composition, at 10-100mum of thickness before forming a junction and at 0.9-2mm equivalent/g of exchange capacity is used for the electrolyte of a solid high molecular fuel cell.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer electrolyte fuel cell (hereinafter referred to as PEFC).

[0002]

2. Description of the Related Art In recent years, fuel cells have been attracting attention due to their characteristics of low pollution and high efficiency. A fuel cell is a cell in which a fuel such as hydrogen or methanol is electrochemically oxidized using oxygen or air to convert the chemical energy of the fuel into electric energy and to extract it.

Such fuel cells are classified into phosphoric acid type, molten carbonate type, solid oxide type, polymer electrolyte type and the like depending on the type of electrolyte used. Among them, PEFC using a cation exchange membrane as an electrolyte has recently been particularly attracting attention because it has good operability at low temperatures and high output density. As shown in FIG. 2, the basic structure of this PEFC main body is an electrolyte membrane 1 composed of a cation exchange membrane.
And each of the positive and negative gas diffusion electrodes 2 and 3 bonded to both sides thereof.
Composed of and. A catalyst is supported on at least the electrolyte membrane 1 side of the gas diffusion electrodes 2 and 3, and a battery reaction occurs at the interface between the catalyst layer and the electrolyte membrane 1 of the gas diffusion electrodes 2 and 3.

Then, for example, hydrogen gas is supplied to the gas diffusion electrode 2, oxygen gas is supplied to the gas diffusion electrode 3, and an external load circuit is connected between the gas diffusion electrodes 2 and 3, respectively. At the interface between the catalyst layer and the electrolyte membrane 1,
The reaction of 2H ₂ → 4H ⁺ + 4e ⁻ occurs. H ⁺ (proton) generated by this reaction passes through the electrolyte membrane 1 and e ⁻
The (electrons) move to the opposite gas diffusion electrode 3 through the load circuit, and the reaction of O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O occurs at the interface between the electrolyte membrane 1 and the catalyst layer of the gas diffusion electrode 3. As a result, electric energy is obtained at the same time as water is generated.

As the electrolyte membrane, a perfluorocarbon sulfonic acid membrane such as Nafion (trademark) or Dow membrane which is a polymer membrane for PEFC is generally used. Also,
As an electrolyte membrane not limited to PEFC, an ultra high molecular weight polyethylene porous membrane having pores filled with an ion exchange membrane (Japanese Patent Laid-Open No. 64-22932) or a surface of the ultra high molecular weight polyethylene porous membrane with a surfactant is used. A membrane (Japanese Patent Laid-Open No. 4-204522) obtained by a method of making it hydrophilic and then including an ion-exchange resin solution is also known.

However, even if the conventional method is used, the output performance may be insufficient depending on the application. Therefore, it has been earnestly desired to develop a PEFC having higher output performance.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a PEFC having high output performance.

[0008]

Means for Solving the Problems As a result of extensive studies to achieve the above object, the thickness of a component having a functional group used as an electrolyte membrane is predicted from the change in the PEFC output characteristics. It is not practical due to the decrease in strength when the film thickness is thin, but it becomes practical when the core material is compounded. It was found that the durability is significantly improved by using a fluorine-containing polymer as the electrolyte component at the same time as using the fluorine-containing polymer as the material, and the present invention has been accomplished.

That is, the present invention provides a polymer electrolyte fuel cell having an ion exchange membrane serving as an electrolyte and a gas diffusion electrode having a catalyst layer, wherein the ion exchange membrane has a functional group-containing component and a fluoropolymer. And a functional group-containing component is a fluorine-containing compound, the exchange capacity is 0.9 to 2 meq / g, and the thickness before formation of the bonded body is 10 to 10. The polymer electrolyte fuel cell has a porosity of 100 to 100 μm and a porosity of 70 to 95% before the composite of the core material.

In the PEFC of the present invention, a component having a functional group of an ion exchange membrane as an electrolyte has a fluorinated polymer as a skeleton, and a functional group includes a sulfonic acid group, a carboxylic acid group, a phosphoric acid group and a phosphonic acid. Those having any one or a plurality of groups are included. As the component having such a functional group, for example, one or more monomers represented by the following formula (1) are essential components, and one or more monomers selected from the monomer group described later There is a copolymer of.

[0011]

[Chemical 1]

(In the formula, -Y is -SO ₃ H, -SO
_{2 F, -SO 2 NH 2,} -SO 3 NH 4, -COOH,
-CN, -COF, -COOR (R is an alkyl group having 1 to 10 carbon atoms), - a PO ₃ H ₂ or -PO ₃ H.
a is an integer of 0 to 6, b is an integer of 0 to 6, and c is 0 or 1.
And a + b + c ≠ 0, and n is an integer of 0 to 6. X is a combination of one or more of Cl, Br and F when n ≧ 1. R _t and R _t ′ are independently selected from F, C1, a perfluoroalkyl group having 1 to 10 carbon atoms and a fluorochloroalkyl group having 1 to 10 carbon atoms. ) And, as a monomer group to be copolymerized with this, tetrafluoroethylene, trifluoromonochloroethylene, trifluoroethylene, vinylidene fluoride, 1,1-difluoro-2,2-dichloroethylene,
Examples include 1,1-difluoro-2-chloroethylene, hexafluoropropylene, 1,1,1,3,3-pentafluoropropylene, octafluoroisobutylene, ethylene, vinyl chloride and alkyl vinyl ester.

After the copolymerization, if necessary, it is converted into a proton-migrating functional group by a post-treatment such as hydrolysis.
The exchange capacity of a component having a functional group is defined as the number of moles of the functional group per gram, and is usually measured by a titration method.
The exchange capacity of the component having a functional group of the present invention is 0.9 to 2
Milliequivalent / g, preferably 1-2 meq / g,
More preferably, it is 1.11-2 meq / g. 0.
If it is less than 9 meq / g, the resistance increases and the performance decreases. On the other hand, when it is more than 2 meq / g, the strength of the film as a structural member is greatly reduced.

The method of forming a component having a functional group of the ion exchange membrane of the present invention by mixing a low molecular weight compound having a functional group with the above-mentioned copolymer is effective for controlling the exchange capacity. In particular, even a high exchange capacity material, which is difficult in a commonly used copolymerization method, can be easily achieved by a method of mixing a low molecular weight compound. The mixing amount of the low molecular weight compound is not particularly limited, but is preferably 50% by weight or less, and if it is more than 50% by weight, the low molecular weight compound may be removed during the fuel cell operation.

The low molecular weight compound may be any compound as long as it has a functional group capable of conducting a proton, but a fluorine-containing compound is a skeleton and a functional group capable of conducting a proton is a sulfonic acid group, a carboxyl group, Those having one or more of a phosphoric acid group and a phosphonic acid group are preferable. For example, the monomer represented by the above formula (1) having the above functional group may be mentioned.

The thickness of the component having a functional group in the ion exchange membrane of the present invention means the cross section of the dried ion exchange membrane before the production of the joined body was observed by a scanning electron microscope (JSM-T20 manufactured by JEOL Ltd.). At this time, the maximum thickness of the film portion where the component having a functional group is present. Its thickness is 10-1
It is necessary that the thickness is 00 μm, and preferably 10 to 8
It is 0 μm. As a result of the studies by the present inventors, it was revealed that the influence of the change in the thickness of the component having a functional group on the output characteristics of the fuel cell is not simply due to the change in the resistance. PE
When H ⁺ moves through the electrolyte membrane in FC, it entrains water present in the membrane. In other words, H ⁺ cannot move unless water is present in the film. The water that accompanies H ⁺ moves from the hydrogen electrode to the oxygen electrode, and as a result, the hydrogen electrode lacks water, while the oxygen electrode has an excessive amount of water including the produced water. Therefore, the output performance is reduced. However, when the thickness of the component having a functional group is 100 μm or less,
It was found that the amount of diffusion of the water on the oxygen electrode side to the hydrogen electrode side through the component having this functional group increases rapidly. FIG. 3 shows the results at 80 ° C. using an aciplex membrane (trade name, manufactured by Asahi Chemical Industry Co., Ltd., exchange capacity: 1.00 meq / g) which is a perfluorocarbon sulfonic acid membrane.

When the thickness of the electrolyte membrane is reduced, the strength is practically reduced. Breakage of the membrane during use as a fuel cell or in the manufacturing process is not preferable in terms of safety and membrane cost. In order to improve the strength of the electrolyte membrane itself, it is effective to combine the core material and the above-mentioned component having a functional group. Further, when used for a fuel cell application, since the two gas diffusion electrodes are joined together, the practical allowable range of the strength of the electrolyte membrane itself is widened. That is, even if the electrolyte membrane itself does not have practical strength, it can be used by forming a joined body.

The porosity of the core material directly affects the output performance.
Here, the porosity is the ratio of the volume of voids to the volume of the core material. The porosity of the core material of the present invention needs to be 70 to 95%, preferably 80 to 95%, and more preferably 80 to 90%. When it is less than 70%, the output performance is seriously deteriorated, and when it is more than 95%, the strength of the composite film becomes insufficient.

A fluorine-containing polymer is used as the material for the core material, and has a melting point above the operating temperature of the fuel cell, 150 ° C.
The above items are preferable. Examples include polytetrafluoroethylene, copolymers of tetrafluoroethylene and perfluoroalkyl vinyl ether, copolymers of tetrafluoroethylene and hexafluoropropylene, and the like. Further, having a functional group similar to the ion exchange membrane on the surface of the core material is effective in improving the adhesion state of the core material and the membrane, for example, a compound having the above-mentioned functional group on the surface of the core material,
For example, there is a method of treating with an aqueous solution of fluoroalkyl (C ₂ -C ₁₀ ) carboxylic acid, perfluorocarbon (C ₄ -C ₁₂ ) sulfonic acid, etc. and coating. The method for producing the core material having pores is not particularly limited. For example, fibers of the core material may be twisted and then woven, or a thin film core material may be stretched. The hot pressing method is effective for reducing the thickness of the core material.

The method of combining the component having a functional group and the core material, which is the ion exchange membrane of the present invention, is not particularly limited. For example, the thin film of the component having a functional group and the core material are superposed and heated and pressurized. There is a way. In this case, in order to remove the gas between the thin film and the core material, it is effective to carry out under a reduced pressure. Further, the component having a functional group is treated with an alcohol such as methanol, ethanol, propanol, butanol, a polar solvent such as N, N'-dimethylacetamide, dimethylsulfosydide, sulfolane, or a cyclic ether such as tetrahydrofuran. There is a method in which a core material is impregnated with one or more solvents selected from solvents or a mixture of these solvents and water and then dried, and the like. The method of impregnation is not particularly limited,
For example, after immersing the core material in the above solution, pulling up,
Further, there is a method of applying or spraying the above-mentioned solution on the core material.

The gas diffusion electrode in the present invention includes a catalyst layer made of a conductive material carrying fine particles of a catalytic metal, and the catalyst layer may include a proton conductive material, a water repellent agent, and a binder as needed. Agents may be included. Further, a layer containing a conductive material not supporting a catalyst and optionally a water repellent or a binder may be formed outside the catalyst layer (on the side not in contact with the electrolyte membrane).

The porosity of the catalyst layer is preferably 65 to 90%.
And more preferably 70 to 85%. When the porosity is less than 65%, the reaction gas supply becomes insufficient, while when it is more than 90%, the conductivity decreases, and as a result, the effect of reducing the thickness of the electrolyte membrane is offset. The catalyst metal used for the gas diffusion electrode may be any metal as long as it promotes the oxidation reaction of hydrogen and the reduction reaction of oxygen, and examples thereof include lead, iron, manganese, cobalt, chromium, gallium, and vanadium. , Tungsten, ruthenium, iridium, palladium, platinum, rhodium or alloys thereof. Further, tungsten carbide can also be used.

The particle size of the metal serving as the catalyst is 10 to 300Å
preferable. The smaller the particle size, the higher the catalytic performance, but 1
If it is less than 0Å, it is difficult to make it realistically.
If it is larger, the required catalyst performance cannot be obtained. More preferred
The particle size of the new catalytic metal is 15 to 100Å. Support for catalyst
The holding amount is 0.01 to 10 mg / when the electrode is molded.
cm²Is preferred. 0.01 mg / cm²Less than catalyst
Performance is not demonstrated, 10 mg / cm ²When you go over
The size becomes larger. More preferably 0.1-0.5 mg
/ Cm ²Is.

The conductive material may be any material as long as it is an electrically conductive material, and examples thereof include various metals and carbon materials. Examples of the carbon material include carbon black such as furnace black, channel black and acetylene black, activated carbon, graphite, carbon fiber and the like, and these may be used alone or in combination.

As the water repellent, for example, fluorinated carbon or the like is used. Various resins are used as the binder, but a fluororesin that also has water repellency is preferable. And
Among the fluororesins, those having a melting point of 400 ° C. or lower are more preferable, and examples thereof include polytetrafluoroethylene and a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether. When these are used, they also serve as a water repellent and a binder.

The proton conductive material may be any compound as long as it has a functional group capable of conducting a proton, but a fluorinated polymer is used as a skeleton, and a functional group capable of conducting a proton is a sulfonic acid group or a carboxylic acid. Those having one or more of a group, a phosphoric acid group and a phosphonic acid group are preferable. As such a proton conductive material, for example, one or more kinds of monomers represented by the above formula (1) are used as essential components, and one kind or two or more kinds of monomers selected from the above-mentioned monomer group are combined therewith. There are copolymers having different structures.

As a method for allowing the proton conductive material to exist in the catalyst layer, the proton conductive material may be mixed with the raw material powder forming the catalyst layer in a solution state or a powder state, and the mixture may be molded to form the catalyst layer. Alternatively, the catalyst layer of the gas diffusion electrode formed in advance may be impregnated with the solution of the proton conductive material. The bonding between the ion exchange membrane, which is the electrolyte, and the gas diffusion electrode is carried out using a device capable of heating and pressurizing. Generally, for example, a hot press machine, a roll press machine or the like is used. The pressing temperature at that time is not particularly limited, but is preferably 120 to 250 ° C. The pressing pressure depends on the hardness of the gas diffusion electrode used, but is, for example, 5 to 20.
It is set to 0 kg / cm ² . If it is less than 5 kg / cm ² , the bonding between the ion exchange membrane and the electrode becomes insufficient, and 200 kg / c
If it exceeds m ² , the gas diffusion electrode has too few pores. The preferred value of pressing pressure is 20 to 100 kg / cm
^{Is 2} .

It is preferable to insert a spacer slightly thinner than the thickness of the electrode at the time of hot pressing because it is possible to prevent the number of holes in the gas diffusion electrode from decreasing. Also,
Hot pressing with the ion exchange membrane moistened with water, a solvent or the like is preferable because the output performance is improved. The reason for this is not clear, but it is considered that the water content in the ion-exchange membrane increases.

Further, if necessary, one side of the gas diffusion electrode or the side of the ion exchange membrane or both sides may be coated with a proton conductive material at the time of joining, and then the surfaces may be joined. This improves the fuel cell output performance probably because the contact between the membrane and the electrode is good. As the reaction gas, hydrogen-based gas obtained by reforming methanol, natural gas, naphtha or the like or hydrogen itself is used as a fuel, and air or oxygen itself is used as an oxidant. Both gases are humidified, if necessary, by adding water or blowing gas into water.

[0030]

EXAMPLES The present invention will be described in detail below with reference to examples.

[0031]

[Example 1] Carbon black (Tokai Black # 550
0 Tokai Carbon Co., Ltd. product name) 18 g, polyoxyethylene (10) octyl phenyl ether (Triton X-100 Wako Pure Chemical Industries, Ltd. product name) 1.25 g
Was added to 450 g of water, and the mixture was stirred and mixed at room temperature for 30 minutes. Next, an aqueous polytetrafluoroethylene dispersion solution (Polyflon D-2 manufactured by Daikin Co., Ltd.) 1 was added to this mixture.
2.9 g and silica gel (Snowtex 50, trade name of Nissan Kagaku Co., Ltd.) 41.5 g were added, and the mixture was stirred and mixed for 30 minutes. The mixture was dried in a hot air drier at 100 ° C. for 2 days. The obtained powder was finely divided by a mill and 5 g was weighed from the fine powder. To this, 16 ml of solvent naphtha (manufactured by Kishida Chemical Co., Ltd.) was added and mixed to form a film. This film was baked in a hot air dryer at 250 ° C. for 1 hour and further at 350 ° C. for 5 minutes. The membrane was washed with a 0.8 mol / l sodium hydroxide solution (water: ethanol = 50: 50% by volume). Then, it was washed with water, and after confirming that it was neutral, it was dried. The obtained film was impregnated with a 12 wt% solution prepared from chloroplatinic acid (special grade manufactured by Wako Pure Chemical Industries, Ltd.) and ethanol (special grade manufactured by Wako Pure Chemical Industries, Ltd.), then dried, and further under a hydrogen atmosphere. The reduction reaction was performed at 150 ° C. The amount of platinum carried was 3.0 mg / cm ² . The porosity of this catalyst layer is measured by a pore size distribution measuring device Poisizer 9320.
It was 76% when measured by (manufactured by Shimadzu Corporation). When 10 cm ² was cut out from this catalyst layer and the weight was measured, it was 0.191 g. 1% of a 5% by weight perfluorocarbon sulfonic acid solution (Nafion solution manufactured by Aldrich Co., Ltd.) was applied to the entire surface from one side of the catalyst layer.
An electrode was prepared by impregnating with 0.24 ml of a solution concentrated to 0% by weight and drying. The weight of this electrode was measured and found to be 0.215 g.

On the other hand, CF ₂ ═CF ₂ and CF ₂ ═CF are used as the functional group precursors of the perfluorocarbon sulfonic acid film.
A film having a thickness of 60 μm made of a copolymer with OCF ₂ CF (CF ₃ ) O (CF ₂ ) ₃ SO ₂ F and a polytetrafluoroethylene film having a film thickness of 10 μm and a porosity of 95% (US GORE- 250 made by TEX)
Integration was performed at 100 ° C. and 100 kg / cm ² . afterwards,
Immerse in a mixed solution of 55% by weight of water, 30% by weight of dimethyl sulfoxide and 15% by weight of calcium hydroxide at 90 ° C.,
Then, it was immersed in a hydrochloric acid aqueous solution to obtain a composite film of a component having a sulfonic acid group (exchange capacity of 1.00 meq / g) and a core material. When the cross section after drying was observed with a scanning electron microscope JSM-T20 (manufactured by JEOL Ltd.), the film thickness was 65 μm with the core material included, and the thickest film thickness in which a component having a functional group was present. Was 60 μm. This film was cut into a size of 36 cm ² , and was cut in 5% by weight hydrogen peroxide water at 80 ° C. for 1 hour.
Soak for 1 hour, then in distilled water at 80 ° C. for 1 hour, and then add to 0.
80 ° C. in 5 mol / l sulfuric acid for 1 hour, 80 ° C. in distilled water,
It was immersed for 1 hour. The obtained film was sandwiched between the above-mentioned two electrodes, and a hot press machine was used to perform a joining treatment at 140 ° C. and 80 kg / cm ^{2 for} 90 seconds.

Using the obtained bonded body, output evaluation was performed by the evaluation device shown in FIG. Pressure 3 atm, cell temperature 95
C., humidification temperature 95.degree. C., oxygen and hydrogen were used as reaction gases, and the flow rates were 100 ml / min and 200 ml / min, respectively. The obtained current density vs. voltage curve is shown in FIG.

[0034]

Comparative Example 1 CF ₂ = CF ₂ and CF ₂ = CFOCF ₂ C
_{F (CF 3) O (CF} 2) 3 the thickness 120μm film comprising a copolymer of SO ₂ F, also 55% by weight of water as in Example 1, dimethyl sulfoxide 30 wt%, calcium hydroxide 15 wt% It was dipped in the mixed solution of and then dipped in an aqueous acid solution to obtain a film having a sulfonic acid group. The thickness of the obtained film was 125 μm. The exchange capacity was 1.00 meq / g. The membrane was cut into a size of 36 cm ² , and the membrane cleaning treatment was performed in the same manner as in Example 1, and then the same bonding with the gas diffusion electrode as in Example 1 was performed under the same conditions. Output evaluation was performed in the same manner as in Example 1 using the obtained joined body, and the results are shown in FIG.

[0035]

Example 2 A perfluorocarbon sulfonic acid membrane (Aciplex, manufactured by Asahi Kasei Kogyo Co., Ltd. with an exchange capacity of 1.00 meq / g trademark) was used at a weight ratio of 50: 5 with ethanol and water.
It was dissolved in 0 mixed solvent to obtain a 5 wt% solution. On the other hand, a porous polytetrafluoroethylene film (MICRO-TE) having a film thickness of 15 μm and a porosity of 90% used as a core material.
X-NTF1033 Nitto Denko Co., Ltd. product name) is fixed to a polystyrene circular ring with an inner diameter of 100 mmφ,
This was immersed in the perfluorocarbon sulfonic acid solution and left at room temperature for 2 hours. Then, the core material was pulled up from the liquid, the excess solution was removed, and air-dried. By repeating this operation 10 times, a composite of a component having a functional group and a core material was obtained. The composite was removed from the circular stick and pinched with tetrafluoroethylene tape (trademark of Naflon Nichias Co., Ltd.), 400 kg / cm ² , 1
Pressed at 40 ° C for 5 minutes. The thickness of the composite film taken out from Naflon (trademark) was 10 μm. Observation with a scanning microscope in the same manner as in Example 1 revealed that the thickness of the component having an ion exchange group was 10 μm. This composite film was kept in pure water at 80 ° C. for 1 hour.

The gas diffusion electrode used in this example (US E
-TEK Inc. Company-made alloy carrying amount 0.40 mg / c
m ² ) is composed of a catalyst layer and a carbon fiber woven fabric part, and the porosity of only the catalyst layer is 74%, which is measured with a pore distribution measuring device Poisizer 9320 (manufactured by Shimadzu Corporation). did. 10 cm ² was cut out from this electrode, and 0.15 m of the above 5 wt% aciplex solution was cut out.
The solution was impregnated with 1 and dried under reduced pressure at 70 ° C. for 2 hours. Made 2
A composite film is sandwiched between one electrode and a tabletop press (manufactured by Tester Sangyo Co., Ltd.) at 140 ° C., 80 Kg / cm ² , 90
Bonding treatment was performed for a second.

[0037]

[Example 3] Porous polytetrafluoroethylene film (MICRO-TEX NTF1033, product name of Nitto Denko Corporation) was added to 0.5% by weight of a fluorine-based surfactant (EF-101, product of Mitsubishi Materials Corporation). It was immersed in an ethanol solution of (N.E.) for one night and then lifted and air-dried. The obtained film was used as a core material.

Next, the core material was dissolved in a perfluorocarbon sulfonic acid membrane (trade name: Aciplex, manufactured by Asahi Kasei Kogyo KK, exchange capacity 1.00 meq / g) in a mixed solvent of 50:50 by weight of ethanol and water. After immersing in the 5% by weight solution thus obtained for 30 minutes, the core material was pulled up, excess liquid was removed, and air drying was performed. This operation was repeated 10 times to obtain a composite of a component having a functional group and a core material. This composite is sandwiched between tetrafluoroethylene tape Naflon and 40
It was pressed at 0 Kg / cm ² and 140 ° C. for 5 minutes. The thickness of the composite film taken out from the Naflon was 11 μm.
When observed with a scanning microscope, the thickness of the component having a functional group was 11 μm. This composite film was kept in pure water at 80 ° C. for 1 hour. Same gas diffusion electrode as in Example 2 (US
10 cm ² of E-TEK) was impregnated with 0.162 ml of the above-mentioned 5% by weight aciplex solution and dried. A composite film is sandwiched between the two electrodes thus prepared, and a desktop press (manufactured by Tester Sangyo Co., Ltd.) is used at 140 ° C., 80 kg / cm ² ,
Bonding treatment was performed for 90 seconds.

[0039]

[Example 4] A porous polytetrafluoroethylene film (MICRO-TEX-NTF1033, manufactured by Nitto Denko Corporation) was used as a 5% by weight perfluorocarbon sulfonic acid solution (Nafion solution manufactured by Aldrich).
The product was immersed in an exchange capacity of 0.91 meq / g, kept at room temperature for 2 hours, then pulled up and air dried. After repeating this operation 10 times, the obtained composite was sandwiched between Naflon and pressed at 400 kg / cm ² and 140 ° C. for 5 minutes. The thickness of the obtained composite was 12 μm. The thickness of the component having a functional group was also 12 μm. The same 10 cm ² gas diffusion electrode (manufactured by E-TEK) as in Example 2 was impregnated with 0.168 ml of a 5 wt% concentration aciplex solution, and dried under reduced pressure at 70 ° C. for 2 hours. The composite is sandwiched between these two electrodes, and a desktop press is used at 140 ° C and 80 kg / cm.
^2. Bonding treatment was performed for 90 seconds.

[0040]

Comparative Example 2 A 5% by weight solution of Aciplex having an exchange capacity of 1.00 meq / g used in Example 2 was cast on a quartz glass plate (manufactured by Nippon Sheet Glass Co., Ltd.) and slowly air-dried at room temperature. . On the quartz glass plate, cracks occurred and a polymer film could not be formed.

[0041]

[Comparative Example 3] A core material having a porosity of 62% and a thickness of 40 μm
Polyethylene terephthalate non-woven fabric (non-woven fabric A020
Asahi Chemical Industry Co., Ltd. product name) was used. Same as Example 2
The same exchange capacity 1.00 m equivalent / g 5 weight of Aciplex
% Of ethanol / water mixed solution in the core material nonwoven fabric A02
After immersing 0 for 1 hour, it was pulled up and air dried at room temperature.
This operation was repeated 15 times, and the obtained membrane was
Scissors 400 kg / cm ²Pressed at 14 ° C for 5 minutes.
As a result, the component having a functional group having a thickness of 38 μm and the core material
A complex of

The same gas diffusion electrode as in Example 2 (US ET
10 cm ^{2 (} manufactured by EK) was impregnated with 0.168 ml of the above-mentioned 5% by weight aciplex solution and dried under reduced pressure at 70 ° C. for 2 hours. The composite is sandwiched between two gas diffusion electrodes,
Bonding treatment was performed at 140 ° C. and 80 kg / cm ² for 90 seconds with a tabletop press.

[0043]

Comparative Example 4 Nafion 117 (trade name, manufactured by DuPont, USA) having an exchange capacity of 0.91 meq / g and a thickness of 175 μm was used as an ion exchange membrane. The same electrode as in Example 2 was used as the electrode, and a joined body was prepared by the same method procedure. Example 2
.About.4, the output was evaluated by the evaluation device shown in FIG. 4 using the joined bodies of Comparative Examples 3 to 4. Pressure 1 atm, cell temperature 55 ° C., humidification temperature 55 ° C., oxygen and hydrogen were used as reaction gases, and flow rates were 200 ml / min and 400 ml / mi, respectively.
It was performed under the condition of n. The obtained current density vs. voltage curve is shown in FIG.
Table 1 shows the respective output voltage values at a current density of 0.8 A / cm @ 2.

[0044]

[Table 1]

[0045]

EFFECTS OF THE INVENTION By using a composite of a component having a functional group and a core material made of a fluorine-containing compound as an electrolyte membrane, a thin film having strength that can be used up to now, which has not been obtained hitherto, can be obtained. Has been achieved.

[Brief description of drawings]

FIG. 1 is a graph showing the results of output evaluation in Example 1 and Comparative Example 1.

FIG. 2 is a schematic diagram showing the basic structure of a polymer electrolyte fuel cell.

FIG. 3 is a graph showing film thickness dependence of water permeability.

FIG. 4 is a schematic diagram showing an evaluation device used in Examples and Comparative Examples.

FIG. 5 is a graph showing the results of output evaluation in Examples 2-4 and Comparative Examples 3-4.

[Explanation of symbols]

 1 Electrolyte Membrane 2 Gas Diffusion Electrode 3 Gas Diffusion Electrode 4 Fuel Cell 5 Humidifier 6 Pure Water 7 Example 1 8 Comparative Example 1 9 Example 2 10 Example 3 11 Example 4 12 Comparative Example 3 13 Comparative Example 4

Claims (1)

[Claims] 1. A polymer electrolyte fuel cell having an ion exchange membrane serving as an electrolyte and a gas diffusion electrode having a catalyst layer, wherein the ion exchange membrane is a core material comprising a component having a functional group and a fluorine-containing polymer. And a component having the functional group is a fluorine-containing compound, the exchange capacity thereof is 0.9 to 2 meq / g, and the thickness before the formation of a joined body is 10 to 100 μm, A polymer electrolyte fuel cell, wherein the porosity of the core material before composite is 70 to 95%.