JPH06295729A - High performance high polymer electrolyte type fuel cell - Google Patents

Abstract

PURPOSE:To provide a fuel cell having excellent output characteristics by mixing a catalyst carrying conductive material, a water repellent agent and a proton conductive material together, and forming a catalyst layer of obtained mixture. CONSTITUTION:A catalyst layer is formed by mixing a catalyst carrying conductive material, a water repellent agent and a proton conductive material together at a specific rate, and in the result the proton conductive material exists through all the area containing the thickness direction of the catalyst layer. As for weight % of the three parties of the catalyst carrying conductive material, the water repellent agent and the proton conductive material in the catalyst layer, the conductive material is 0.400-0.995, and the water replellent agent is 0-0.550, and the proton conductive material is 0.005-0.080. When this specific mixing rate is not satisfied, an expected effect cannot be attained.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Due to the characteristics of low pollution and high efficiency,
Fuel cells are receiving attention. A fuel cell electrochemically oxidizes a fuel such as hydrogen or methanol using oxygen or air to take out the chemical energy of the fuel as electric energy. It is classified into an acid type, a molten carbonate type, a solid oxide type, etc. depending on the type of electrolyte used. Among these, PEF has been particularly popular in recent years due to its characteristics of low temperature operation and high power density.
C has received attention.

The basic structure of PEFC will be described with reference to FIG. As shown in FIG. 2, the battery body is constituted by joining gas diffusion electrodes to both sides of the solid polymer electrolyte membrane. A catalyst is supported on the gas diffusion electrode,
The cell reaction occurs at the joint interface between the solid polymer electrolyte membrane and the gas diffusion electrode. For example, when hydrogen gas is flown through the gas diffusion electrode 2, a reaction of 2H ₂ → 4H ⁺ + 4e ⁻ occurs at the bonding interface with the film. H ⁺ moves to the counter electrode gas diffusion electrode 1 through the solid polymer electrolyte membrane 3. When oxygen gas is passed through the gas diffusion electrode 1, a reaction of O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O occurs at the interface between the membrane and the electrode, water is generated, and at the same time, electrode energy is obtained.

As described above, since an electrochemical reaction occurs at the interface between the membrane and the gas diffusion electrode through the electrolyte membrane and in the presence of the catalyst, the width of the interface directly affects the output performance. However, in order to widen the interface, after dissolving the proton conductive material in a solvent and applying it on the electrode surface and then joining with the ion exchange membrane, or after premixing powdery solid polymer electrolyte with the electrode constituent carbon Create an electrode
1-67787, Japanese Patent Laid-Open No. 61-67788). Bonding of these electrodes and the ion exchange membrane is performed by applying pressure while heating.

However, its output performance is insufficient and further improvement is desired.

[0006]

An object of the present invention is to provide a fuel cell having excellent output performance.

[0007]

Means for Solving the Problems As a result of intensive studies on the structure of the catalyst layer of the gas diffusion electrode, the present inventors have found that a catalyst-carrying conductive material in which a catalyst is carried on a hydrophilic conductive material having at least a large specific surface area and a hydrophobic material. The present inventors have found that the battery output is increased by mixing a solution of a water-repellent agent having a hydrophilic property with a solution of a proton conductive material having a hydrophilic group and forming a catalyst layer from the obtained mixture, and thus the present invention has been accomplished.

That is, according to the present invention, in a fuel cell in which an ion exchange membrane as an electrolyte and a gas diffusion electrode having a catalyst layer are joined, the catalyst layer is at least a catalyst-supporting conductive material, a water repellent, and a proton conductive material. Is mixed and then molded so that the proton conducting material exists in the entire region including the thickness direction of the catalyst layer, and in the catalyst layer, a conductive material carrying a catalyst and The weight fractions of the water repellent and the proton conductive material are 0.400 to 0.995 of the conductive material, 0 to 0.550 of the water repellent, and 0.005 to 0.08 of the proton conductive material.
It is a high-performance polymer electrolyte fuel cell characterized by being 0.

The ion exchange membrane used as an electrolyte in the present invention is preferably one having at least one of a sulfonic acid group, a carboxylic acid group, a phosphonic acid group, and a phosphoric acid group as a skeleton of a fluoropolymer. However, a film obtained by introducing a monomer having a sulfonic acid group or a carboxylic acid group into a polyolefin film such as polyethylene by a graft polymerization reaction or the like can also be used.

Examples of the fluorine-containing polymer film include tetrafluroethylene, trifluoromonochloroethylene,
Trifluoroethylene, vinylidene fluoride, 1,1-difluoro-2,2-dichloroethylene, 1,1-difluoro-2-chloroethylene, hexafluoropropylene, 1,1,1,3,3-pentafluoropropylene,
Octafluoroisobutylene, ethylene, vinyl chloride,
And a first group of monomers such as alkyl vinyl esters,
Following general formula _{(1), Y- (CF 2} ) a - (CFR f) b - (CFR f) c -O- - _{[CF (CF 2 X) -CF 2} -O ] _n -CF = CF ₂ ... ...... (1) (wherein, Y is _{-SO 2 F, -SO 3 NH,} -COO
H, -CN, -COF, COOR (R has 1 to 10 carbon atoms
Alkyl group) in, - PO ₃ H _2, a -PO ₃ H, a
Is 0-6, b is 0-6 NO integer, c is 0 or 1, provided that a + b + c is not equal to 0. X is n>
When 1, it is C1, Br, F or a mixture thereof,
n is 0-6. R _f and R ′ _f are independently F, C
It is selected from the group consisting of perfluoroalkyl groups having 1, 1 to about 10 carbon atoms and fluorochloroalkyl groups having 1 to 10 carbon atoms. ) Is a copolymer of two or more kinds, usually 2 to 3 kinds, selected from the second group of monomers represented by the formula (1) as an essential constituent of the second group of monomers.

The proton conducting material may be any material that conducts protons, preferably at least --SO ₃ H,-
COOH, is a fluorine-containing hydrocarbon having one among the -PO ₃ H ₂ and -PO ₃ H. For example, a copolymer of 2 or 3 or more kinds of monomers essentially including a second group of monomers selected from the first group of monomers and the second group of monomers, or one or more of the second group of monomers. Polymer,
Examples thereof include the second group of monomers.

It is sufficient that two or more molecules of the monomer are bonded to the polymer, and the molecular weight thereof is preferably 5,000 or more.
The larger the molecular weight, the better the entanglement of the catalyst layer with the conductive material, which is more preferable in terms of durability. It is preferable to use a mixture of the polymer and the low molecular weight compound, and further mixing makes it possible to increase the amount of functional groups (the number of equivalents of functional groups per 1 g).

Examples of the proton conducting material include alcohols such as methanol, ethanol, propanol and butanol, polar solvents such as N, N'-dimethylacedamide, N, N'-dimethylformamide, dimethylsulfoxide and sulfolane, and tetrahydrofuran. And the like, and a mixture of two or more kinds selected from the above solvent group, and further dissolved in an aqueous medium such as a mixture of the above solvent group and water. Particularly, a mixture of ethanol and water and a mixture of propanol and water are preferable.

As the catalyst metal, hydrogen oxidation reaction or
Is anything that has a catalytic effect on the reduction reaction of oxygen
For example, lead, iron, manganese, cobalt, chromium, molybdenum
Lithium, vanadium, tungsten, ruthenium, iris
Indium, platinum, palladium, rhodium, or a combination thereof
You can choose from gold. Catalyst particle size is 10-300
Å is good, preferably 15 to 100 Å. 10Å not yet
It is difficult to create a full one, while 300Å
If it is too large, the catalyst performance will decrease. The amount of catalyst supported depends on the electrode
0.01 to 10 mg / cm after shaping²And is preferred
Specifically 0.1-0.5 mg / cm²Is. The catalyst is 0.
01 mg / cm ²If less than 10%, the performance will decrease, while 10mg
/ Cm²The larger the cost, the higher the cost of the catalyst.

The catalyst-supporting conductive material used in the present invention is such that the catalyst is supported in advance and then mixed with the water repellent agent, the proton conducting material, etc. before being mixed with the catalyst layer. The conductive material forming the catalyst layer may be any electronic conductive material, and examples thereof include various metals and carbon materials. Examples of the carbon material and the like include carbon black such as furnace black, channel black and acetylene black, activated carbon, graphite, carbon fiber and the like, which can be used alone or in combination. It is preferable that the carbon material for supporting the catalyst is more hydrophilic and has good compatibility with the functional group of the proton conducting material.
It has a specific surface area of 10 to 3000 m ² / g. On the other hand, the catalyst carries no, may be allowed to coexist more hydrophobic carbon material, a specific surface area of 0.1m ² / g~10m less than ² / g of the carbon material used in this case.

The water-repellent agent removes the water generated by the electrode reaction or the water that humidifies the reaction gas, and forms a passage for supplying the reaction gas to the reaction point. Therefore,
Those having a contact angle with water of more than 90 ° are preferable, and fluorine-containing compounds are particularly preferable. Specific examples include polyethylene, polystyrene, polypropylene, polytetrafluoroethylene, polytrifluoroethylene, polychlorotrifluoroethylene, and tetrafluoroethylene-perfluoroalkylvinylether copolymer.

A binder may coexist. The binder holds the constituent substances of the electrode catalyst layer, and various kinds of finger are used. It can be used also as the water repellent. A Teflon-based compound having a melting point of 400 ° C. or lower is preferable, and examples thereof include polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkylvinyl ether copolymer, and tetrafluoroethylene-hexafluoropropylene copolymer.

In the catalyst layer, the conductive material carrying the catalyst, the water repellent, and the proton conductive material are mixed in a weight fraction of 0.400 to 0.995 for the conductive material and the water repellent for the mixture. Is 0.0
00 to 0.550, and the proton conductive material is 0.005 to 0.
It is 080. The weight fraction of the conductive material at this time is calculated excluding the supported catalyst. The area of the present invention in the composition comprising a carbon material as a carbon material supporting a catalyst, polytetrafluoroethylene as a water repellent, perfluorocarbon sulfonic acid as a proton conductive material, and Aciplex (registered trademark of Asahi Kasei Kogyo) It is shown in FIG. The proton conducting material is indispensable for increasing the number of reaction points in the catalyst layer, and therefore its weight fraction is 0.0
If it is less than 05, the effect of increasing the number of reaction points is reduced and it does not contribute to the improvement of performance. On the other hand, when the weight fraction of the proton conducting material is more than 0.080, the influence of its hydrophilicity becomes large, and the humidified water or generated water cannot be smoothly removed outside the cell system, which causes the reaction gas to react. The output performance is significantly reduced because it is no longer supplied to the. The electronic conductivity of the carbon material supporting the catalyst plays an important role. Therefore, when the weight fraction is less than 0.400, the output performance is remarkably reduced, presumably because the contact points between the carbon materials are reduced and the conductivity is reduced. Polytetrafluoroethylene used as a water repellent has an action of removing humidified water and generated water, but has a weight fraction of 0.
It has been clarified that when it is more than 550, the output performance is deteriorated probably because the conductivity of the carbon material is decreased.

Next, a method for producing the fuel cell of the present invention will be described. A predetermined amount of water, a catalyst-carrying carbon material as a catalyst-carrying and carrying conductive material, a proton conducting material, and a water repellent are mixed to obtain a uniformly dispersed state. The catalyst layer is formed by molding this into a required shape or directly applying it to the electrolyte membrane. A conductive material not supporting a catalyst may be added at the same time. Alternatively, the homogeneous mixture may be dried and a solvent may be added to form a paste.

During a series of mixing operations, the proton conductive material having a hydrophilic functional group gathers around the more hydrophilic catalyst-carrying carbon material, and the catalyst-carrying carbon material itself also gathers. On the other hand, it becomes more hydrophobic. It is presumed that water-repellent agents that are water-soluble will collect. This creates a state in which the hydrophilic part and the hydrophobic part are microscopically separated, and the hydrophilic part is an effective passageway for mainly protons and humidifying water and generated water, and the hydrophobic part is mainly for the passage of reaction gas. Become. As described above, by mixing all the constituent materials of the catalyst layer in the powder state, an effect which is not found in the conventional knowledge is exhibited.

In the present invention, the proton conductive material is present in the entire area including the thickness direction of the catalyst layer. This means that the catalyst layer is uniformly distributed not only on the surface side of the catalyst layer but also in the entire region. In the following measurement method, uniformity means within ± 15% of the average value of the proton conducting material amount. It comes in. The amount of the proton conducting material is determined by adsorbing Ba on the functional group and measuring the Ba by an electron beam probe-analysis method. First, the electrode catalyst layer is stored in a 0.1 mol / liter barium chloride aqueous solution at room temperature for 10 hours, and then washed with excess pure water while renewing the liquid. By drying, a catalyst layer having barium adsorbed on the functional groups of the proton conducting material can be obtained. This is embedded in an epoxy resin and the cross section of the catalyst layer is cut using a microtome to obtain a measurement surface. Carbon vapor deposition is applied to this sample amount to obtain a measurement sample. Using an electron probe microanalyzer JCXA-733 (manufactured by JEOL Ltd.), measurement was carried out under the conditions of an accelerating voltage of 15 kV, a sample current of 0.5 μA, an analytical line Ba Lα line, and a spectroscopic crystal pentaerythritol.

The measurement results of the catalyst layers of Example 2 and Comparative Example 1 described later are shown in FIG. 9 as an example. The thickness of the catalyst layer of Example 2 is about 120 μm. Maximum count is 330 cp
s, the minimum count is 280 cps, and the average count is 3
It was 05 cps. On the other hand, the thickness of the catalyst layer in Comparative Example 1 was about 200 μm, and it can be seen that the proton conducting material is mainly present on the surface.

The gas diffusion electrode has this catalyst layer as an essential element, and may be a laminate with, for example, another conductive material. For example, preferably, it may be used as a composite of cloth using carbon fibers. Bonding of the membrane and the gas diffusion electrode is performed using a device capable of heating and pressurizing. There is no specific device, and for example, a hot press machine, a roll press machine or the like is generally used. The pressing temperature may be the glass transition temperature of the used electrolyte membrane or higher, and preferably 120 to 18
It is 0 ° C. The pressing pressure depends on the hardness of the gas diffusion electrode used and is about 5 to 200 kg / cm ² , preferably 20 to 100 kg / cm ² . At pressures lower than 5 kg / cm ^2, the adhesion between the membrane and the electrode becomes insufficient, while at pressures higher than 200 kg / cm ² , the reduction of electrode vacancies becomes large.

It is effective to insert a spacer thinner than the thickness of the electrode during hot pressing. Further, hot pressing may be performed while the electrolyte membrane is wet in the coexistence of water.
If necessary, a proton conducting material may be newly applied on one surface of the catalyst layer or the surface of the ion exchange membrane or both at the time of bonding, and then bonding may be performed on the applied surface. This improves fuel cell performance, perhaps due to better contact between the membrane and the electrodes.

As the reaction gas, hydrogen-based gas obtained by decomposing 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 by adding water or blowing gas into water, if necessary. Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to the examples.

[0026]

【Example】

[0027]

Example 1 Tokai Black # 5500 (trademark manufactured by Tokai Carbon Co., Ltd.) 36 g, chloroplatinic acid [special grade manufactured by Wako Pure Chemical Industries, Ltd.] and ethanol [special grade manufactured by Wako Pure Chemical Industries, Ltd.] 10 321 ml of the wt% solution was mixed well and then dried. This mixed powder under a hydrogen atmosphere,
It was processed at 150 ° C. From the weight measurement, Tokai Black 1
336 mg of platinum was supported per gram.

48 g of this platinum-supported Tokai Black, 2.5 g of Triton X-100 [trademark of Wako Pure Chemical Industries, Ltd.], 700 g of distilled water, 26 g of Polyflon D-2 [registered trademark of Daikin Corporation], and 5 weights % Nafion solution [trademark of Aldrich Co.] 72.6 g was added and mixed with stirring for 30 minutes. The weight fraction of each component is carbon 0.651,
The water repellent is 0.283 and the proton conductive material is 0.066.
The mixture was dried at 100 ° C. in a hot air dryer. The obtained powder was finely divided by a mill and 5 g was weighed from the fine powder.
32 ml of solvent naphtha (manufactured by Kishida Chemical Co., Ltd.) was added to this under a nitrogen atmosphere, and after mixing, a film was formed on a suspension 304 plate. The film was dried under reduced pressure and then treated in nitrogen at 250 ° C. for 1 hour. The thickness of the obtained catalyst layer was 200 μm, and 10 cm ² was cut out from this catalyst layer and the weight was measured and found to be 0.222 g. Catalyst loading amount is 4 mg
Was / cm ² . This catalyst layer was used as an electrode.

Two electrodes and an Acip with a thickness of 100 μm
A fuel cell of the present invention was produced by joining a lex membrane [registered trademark of Asahi Kasei Kogyo KK] with an exchange capacity of 1.00 μm by hot pressing at 140 ° C. for 90 seconds.

[0030]

Comparative Example 1 Tokai Black # 5500 (trademark manufactured by Tokai Carbon Co., Ltd.) 36 g and Triton X-100 (trademark manufactured by Wako Pure Chemical Industries, Ltd.) 2.5 g were added to 700 g of water, and the mixture was stirred and mixed at room temperature for 30 minutes. . Next, 26 g of Polyflon D-2 [trademark of Dickin Co., Ltd.] was added to this mixture, and the mixture was stirred and mixed for 30 minutes. This mixture was heated in a hot air dryer at 100 ° C,
It was dried for 2 days. The obtained powder was pulverized with a mill, and 5 g was weighed from this. To this, 32 ml of solvent naphtha (manufactured by Kishida Chemical Co., Ltd.) was added, and after mixing, a film was formed on a suspension 304 plate. This film was baked in a hot air dryer at 250 ° C. for 1 hour and further at 350 ° C. for 5 minutes. The obtained membrane was impregnated with a 10 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.], followed by drying, and further under a hydrogen atmosphere, The reduction reaction was performed at 150 ° C. The amount of platinum supported was 4 mg / cm ² . When 10 cm ² was cut out from this catalyst layer and weighed, it was 208 g. This catalyst layer was impregnated with 0.24 g of a 5% by weight Nafion solution (manufactured by Aldrich) and dried to prepare an electrode. When the weight was measured, it was 0.211 g. Using this electrode, bonding with the Aciplex film was performed as in Example 1.

The output performance of the fuel cell thus produced was evaluated by the single cell evaluation apparatus shown in FIG. Using oxygen gas and hydrogen gas, the gas flow rate is H ₂ 100 ml /
min, O ₂ 50 ml / min, cell temperature 55 ° C., humidification temperature 70 ° C., and normal pressure. The result is shown in Figure 1.
It was shown to.

[0032]

[Example 2] 1.20 g of carbon black supporting 20% by weight of platinum (manufactured by E-TEK, USA) in 2 g of pure water, 1.11 g of Polyflon D-2 (registered trademark of Daikin Co., Ltd.),
Aciplex, a perfluorocarbon sulfonic acid
(Registered trademark of Asahi Kasei Corporation) Exchange capacity 1.19
Meg / g 5 wt% ethanol / water (50 wt.
(Weight) 2 g of the solution was added, and the mixture was stirred with a magnetic stirrer (manufactured by Mitamura Riken Co., Ltd.) for 2 hours at room temperature to obtain a uniform paste. The weight fraction of the mixed constituents is carbon 0.566, water repellent polytetrafluoroethylene 0.377, and proton conductive material 0.057.

Naflon (registered trademark manufactured by Nichias Corporation), which is a polytetrafluoroethylene sheet, thickness 0.0
It was cut into an area of 5 cm and 10 cm ² , and the above-mentioned paste-like material was applied to the upper surface thereof to form a film having a thickness of 100 μm. With two sheets of this paste-like material, sandwiching Aciplex, which is a perfluorocarbon sulfonic acid film having a thickness of 50 μm and an exchange capacity of 1.00 meg / g, and using a tabletop press (manufactured by Tester Sangyo Co., Ltd.), 80 kg / cm
^2. Pressed at 140 ° C. for 90 seconds. Then, the Naflon was removed from the obtained joined body.

[0034]

[Example 3] Platinum 20% by weight supported carbon black (manufactured by E-TEK, USA) 1.20 g, polyflon D-2 (registered trademark manufactured by Daikin Co., Ltd.) 1.67 g, in 2 g of pure water.
Aciplex, a perfluorocarbon sulfonic acid
(Registered trademark of Asahi Kasei Corporation) Exchange capacity 1.19
Meg / g 5 wt% ethanol / water (50 wt.
(Weight) 2 g of the solution was added, and the mixture was stirred with a magnetic stirrer (manufactured by Mitamura Riken Co., Ltd.) for 2 hours at room temperature to obtain a uniform paste. The weight fraction of the mixed constituents is 0.476 of carbon, 0.476 of polytetrafluoroethylene which is a water repellent, and 0.048 of the proton conducting material.

The pasty material obtained and the exchange capacity of 1.0
Aciplex (registered trademark manufactured by Asahi Kasei Co., Ltd.), which is a perfluorocarbon sulfonic acid film of 0 meg / g
Using, the joined body was produced under the same means and conditions as in Example 2.

[0036]

Example 4 Platinum 20% by weight supported carbon black (manufactured by E-TEK, USA) 1.20 g, Polyflon D-2 (registered trademark manufactured by Daikin Co., Ltd.) 0.71 g, in 2 g of pure water.
Aciplex, a perfluorocarbon sulfonic acid
(Registered trademark of Asahi Kasei Corporation) Exchange capacity 1.19
Meg / g 5 wt% ethanol / water (50 wt.
(Weight) 2 g of the solution was added, and the mixture was stirred with a magnetic stirrer (manufactured by Mitamura Riken Co., Ltd.) for 2 hours at room temperature to obtain a uniform paste. The weight fraction of the mixed constituents is carbon 0.654, water repellent polytetrafluoroethylene 0.280, and proton conductive material 0.065.

The paste-like material obtained and the exchange capacity of 1.0
Aciplex (registered trademark manufactured by Asahi Kasei Co., Ltd.), which is a perfluorocarbon sulfonic acid film of 0 meg / g
Using, the joined body was produced under the same means and conditions as in Example 2.

[0038]

[Example 5] Platinum 20% by weight supported carbon black (manufactured by E-TEK, USA) 1.20 g, Polyflon D-2 (registered trademark, manufactured by Daikin Co., Ltd.) 1.11 g, in 2 g of pure water.
Aciplex, a perfluorocarbon sulfonic acid
(Registered trademark of Asahi Kasei Corporation) Exchange capacity 1.19
Meg / g 5 wt% ethanol / water (50 wt.
(Weight) 1.0 g of the solution was added, and the mixture was stirred with a magnetic stirrer (manufactured by Mitamura Riken Co., Ltd.) for 2 hours at room temperature to obtain a uniform paste. The weight ratio of the mixed constituents is carbon 0.583, water repellent polytetrafluoroethylene 0.388, and proton conductive material 0.005.

Obtained paste-like material and exchange capacity 1.0
Aciplex (registered trademark manufactured by Asahi Kasei Co., Ltd.), which is a perfluorocarbon sulfonic acid film of 0 meg / g
Using, the joined body was produced under the same means and conditions as in Example 2.

[0040]

Example 6 Platinum 20% by weight supported carbon black (manufactured by E-TEK, USA) 1.20 g, perfluorocarbon sulfonic acid Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.) exchange capacity 1.19 meg / g
1.0 g of a 5% by weight ethanol / water solution (50% by weight to 50% by weight) was added and stirred with a magnetic stirrer (manufactured by Mitamura Riken Co., Ltd.) for 2 hours at room temperature to obtain a uniform paste. The weight fraction of the mixed composition is 0.9
52 and a proton conducting material of 0.048.

The paste-like material obtained and the exchange capacity of 1.0
Aciplex (registered trademark manufactured by Asahi Kasei Co., Ltd.), which is a perfluorocarbon sulfonic acid film of 0 meg / g
Using, the joined body was produced under the same means and conditions as in Example 2.

[0042]

[Comparative Example 2] 1.20 g of carbon black supporting 20% by weight of platinum (manufactured by E-TEK, USA) in 2 g of pure water, 1.11 g of Polyflon D-2 (registered trademark of Daikin Co., Ltd.),
Aciplex, a perfluorocarbon sulfonic acid
(Registered trademark of Asahi Kasei Corporation) Exchange capacity 1.19
Meg / g 5 wt% ethanol / water (50 wt.
(Weight) 8.0 g of the solution was added, and the mixture was stirred with a magnetic stirrer (manufactured by Mitamura Riken Co., Ltd.) at room temperature for 2 hours to obtain a uniform paste. The weight fraction of the mixed constituents is 0.483 of carbon, 0.322 of polytetrafluoroethylene which is a water repellent, and 0.194 of a proton conducting material.

The paste-like product obtained and the exchange capacity of 1.0
Aciplex (registered trademark manufactured by Asahi Kasei Co., Ltd.), which is a perfluorocarbon sulfonic acid film of 0 meg / g
Using, the joined body was produced under the same means and conditions as in Example 2.

[0044]

[Comparative Example 3] 1.20 g of carbon black supporting 20% by weight of platinum (manufactured by E-TEK, USA) in 2 g of pure water, 1.11 g of Polyflon D-2 (registered trademark of Daikin Co., Ltd.),
Aciplex, a perfluorocarbon sulfonic acid
(Registered trademark of Asahi Kasei Corporation) Exchange capacity 1.19
Meg / g 5 wt% ethanol / water (50 wt.
(Weight) Solution (3.06 g) was added, and the mixture was stirred with a magnetic stirrer (manufactured by Mitamura Riken Co., Ltd.) at room temperature for 2 hours to obtain a uniform paste. The weight fraction of the mixed constituents is carbon 0.508, water repellent polytetrafluoroethylene 0.339, and proton conductive material 0.153.

Obtained paste-like material and exchange capacity 1.0
Aciplex (registered trademark manufactured by Asahi Kasei Co., Ltd.), which is a perfluorocarbon sulfonic acid film of 0 meg / g
Using, the joined body was produced under the same means and conditions as in Example 2.

[0046]

[Comparative Example 4] Platinum 20% by weight supported carbon black (manufactured by E-TEK, USA) 1.20 g, Polyflon D-2 (registered trademark manufactured by Daikin Corporation) 2.0 g, and perfluorocarbon sulfonic acid in 2 g of pure water. Aciplex
(Registered trademark of Asahi Kasei Corporation) Exchange capacity 1.19
Meg / g 5 wt% ethanol / water (50 wt.
2.41 g of the solution was added, and the mixture was stirred with a magnetic stirrer (manufactured by Mitamura Riken Co., Ltd.) for 2 hours at room temperature to obtain a uniform paste. The weight fraction of the mixed constituents is carbon 0.377, water repellent polytetrafluoroethylene 0.566, and proton conductive material 0.057.

Obtained paste-like material and exchange capacity 1.0
Aciplex (registered trademark manufactured by Asahi Kasei Co., Ltd.), which is a perfluorocarbon sulfonic acid film of 0 meg / g
Using, the joined body was produced under the same means and conditions as in Example 2.

[0048]

[Comparative Example 5] Platinum 20% by weight supported carbon black (manufactured by E-TEK, USA) 1.20 g, Polyflon D-2 (registered trademark manufactured by Daikin Co., Ltd.) 0.89 g, in 2 g of pure water.
Aciplex, a perfluorocarbon sulfonic acid
(Registered trademark of Asahi Kasei Corporation) Exchange capacity 1.19
Meg / g 5 wt% ethanol / water (50 wt.
2.41 g of the solution was added, and the mixture was stirred with a magnetic stirrer (manufactured by Mitamura Riken Co., Ltd.) for 2 hours at room temperature to obtain a uniform paste. The weight fraction of the mixed constituents was carbon 0.551, water repellent polytetrafluoroethylene 0.367, and proton conductive material 0.083.

The paste-like material obtained and the exchange capacity of 1.0
Aciplex (registered trademark manufactured by Asahi Kasei Co., Ltd.), which is a perfluorocarbon sulfonic acid film of 0 meg / g
Using, the joined body was produced under the same means and conditions as in Example 2. The output performance was evaluated by the single cell evaluation apparatus shown in FIG. 3 using the joined bodies produced in the above-mentioned Examples 2 to 6 and the joined bodies produced in Comparative Examples 2 to 5. Using oxygen gas and hydrogen gas, the gas flow rate is H ₂ 200 ml / mi
n, O ₂ 400 ml / min, gas pressure is 5 atm for both gases, humidifier and cell temperature are 95 ° C. The obtained results are shown in FIGS.

[0050]

The output performance of the fuel cell of the present invention is greatly improved.

[Brief description of drawings]

FIG. 1 is a graph showing current density vs. cell voltage of evaluation results of Example 1 and Comparative Example 1.

FIG. 2 is an explanatory view showing a joined body of a solid polymer electrolyte fuel cell.

FIG. 3 is an explanatory diagram showing a bonded body evaluation apparatus used in Examples and Comparative Examples.

FIG. 4 is a graph showing the current density vs. cell voltage of the evaluation results of Example 2 and Comparative Example 2.

FIG. 5 is a graph showing the current density vs. cell voltage of the evaluation results of Example 3 and Example 4.

FIG. 6 is a graph showing current density vs. cell voltage of evaluation results of Example 5 and Comparative Example 3.

FIG. 7 is a graph showing current density vs. cell voltage of evaluation results of Example 6, Comparative Example 4 and Comparative Example 5.

FIG. 8 is a composition diagram showing weight fractions of a carbon material supporting a catalyst of a catalyst layer, tetrafluoroethylene, and perfluorocarbon sulfonic acid.

9 is a diagram showing the results of electron probe microanalysis of the catalyst layers of Example 2 and Comparative Example 1. FIG.

[Explanation of symbols]

 1 Oxygen Electrode Gas Diffusion Electrode 2 Hydrogen Electrode Gas Diffusion Electrode 3 Solid Polymer Electrolyte Membrane 4 Fuel Cell 5 Humidifier 6 Pure Water

Claims (1)

[Claims] 1. A fuel cell in which an ion-exchange membrane, which is an electrolyte, and a gas diffusion electrode having a catalyst layer are joined, and the catalyst layer mixes at least a catalyst-supporting conductive material, a water repellent, and a proton conductive material. The catalyst layer is characterized in that the proton conductive material is present in the entire region including the thickness direction of the catalyst layer by molding, and the conductive material and the water repellent agent carrying the catalyst are formed in the catalyst layer. The weight fraction of the three proton conducting materials is
Conductive material 0.400 to 0.995, water repellent 0 to 0.55
A high-performance polymer electrolyte fuel cell, characterized in that it has a proton conductivity of 0.005 to 0.080.