JP2003173788A - Gas diffusion layer for polymer electrolyte fuel cell and electrolyte membrane/electrode joint body as well as polymer electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a polymer electrolyte fuel cell capable of a stable operation for long period of time through supply of a gas diffusion layer or a gas diffusion electrode with improved basic functions as a cell, enabling a uniform moisture control over the whole surface of an electrolyte membrane/electrode joint body (MEA). <P>SOLUTION: A gas diffusion layer 213a having a polymer-containing conductive layer 22a consisting of conductive carbon particles 210a, 211a with different volume of acid functional group and a polymer material 212a is formed on a porous support body 21a. On the surface of the gas diffusion layer 213a, a catalyst layer 23a containing conductive carbon particles holding platinum is arranged to structure a gas diffusion electrode 24a. Mixing volume of the conductive carbon particles 211a with a plenty of acid functional group volume is increased from one end (R2) of the gas diffusion electrode 24a toward the other end (L2). <P>COPYRIGHT: (C)2003,JPO

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 useful as a power generator for mobile bodies such as consumer cogeneration and automobiles, and an electrolyte membrane-electrode assembly and a gas diffusion layer used therein. is there.

[0002]

2. Description of the Related Art A polymer electrolyte fuel cell supplies a fuel gas such as hydrogen and an oxidant gas such as air (generally, the fuel gas supply side is called an anode electrode, and the oxidant gas supply side is a cathode). It is called an electrode), which reacts electrochemically on a catalyst such as platinum, which simultaneously generates electricity and heat. An outline of a general configuration of such a polymer electrolyte fuel cell is shown in FIG.

In FIG. 1, on both sides of a polymer electrolyte membrane 11 for selectively transporting hydrogen ions, a catalyst layer 12 containing carbon powder carrying a platinum-based metal catalyst as a main component is closely arranged. Further, on the outer surface of the catalyst layer 12, a pair of gas diffusion layers 13 composed of a porous support having pores are arranged in close contact with the catalyst layer 12. Usually, the porous support is made of carbon nonwoven fabric such as carbon paper or carbon cloth. The gas diffusion layer 14 and the catalyst layer 12 form a gas diffusion electrode 14. The gas diffusion electrode may be simply referred to as an electrode.

On the outside of the gas diffusion electrode 14, an electrolyte membrane-electrode assembly (hereinafter referred to as MEA) 15 formed of the gas diffusion electrode 14 and the polymer electrolyte membrane 11 is mechanically fixed, and adjacent MEAs are connected to each other. Are electrically connected in series to each other, a reaction gas is further supplied to the gas diffusion electrode, and a gas passage 16 for carrying away water and surplus gas generated by the reaction is formed on one surface of the separator plate 17 To place. The gas flow path may be provided separately from the separator plate 17, but it is common to provide a groove on the surface of the separator plate to form the gas flow path. Further, a gasket 18 is sandwiched between the polymer electrolyte membrane 11 and the separator plate 17 in order to prevent the reaction gas from leaking.

During operation of the battery, oxygen or air, which is a reaction active material, diffuses from the gas channel to the catalyst layer through the gas diffusion layer at the cathode electrode, and at the same time, gas is diffused from the catalyst layer due to the permeation effect generated by the reaction. Excess water that has permeated into the layer is removed from the pores of the gas diffusion layer together with the surplus gas to the outside of the battery.

[0006]

In the polymer electrolyte fuel cell, since the polymer electrolyte membrane has the property that its ionic conductivity becomes higher as the water content increases, the polymer electrolyte membrane is wetted. It is necessary to keep the condition. For this reason, in general, the reaction gas is preliminarily humidified to a predetermined humidity so that the moisture retention property of the polymer electrolyte membrane is secured at the same time as the supply of the reaction gas.

As a result of the electrode reaction, a part of the water generated is caused to flow from the inlet side to the outlet side of the gas flow channel together with the reaction gas flowing in the gas flow channel of the separator plate, and finally to the outside of the fuel cell. Be drained. Therefore, the amount of water contained in the reaction gas in the fuel cell differs in the flow direction of the reaction gas, and the amount of water contained in the reaction gas is larger at the outlet side than at the inlet side of the reaction gas. Therefore, compared to the inlet side of the gas flow path, the outlet side is in a high humidity state above a predetermined level. For this reason, in the vicinity of the outlet side, the function of draining water from the gas diffusion layer deteriorates, and in extreme cases, a flooding phenomenon occurs in which the pores of the gas diffusion layer are clogged with excess water. There has been a problem that the diffusibility of gas is hindered and the battery voltage drops extremely.

On the contrary, in order to suppress the occurrence of the flooding phenomenon on the outlet side, when the reaction gas whose humidity is lowered in advance is supplied from the inlet side, the water content of the polymer electrolyte membrane lowers near the inlet side. However, there has been a problem in that the proton conductivity is lowered, that is, the proton conductivity is increased, so that the battery voltage is lowered. These tendencies were more remarkable as the electrode area was larger and the gas passage of the separator plate was longer.

As a solution to such a problem, there is a technique described in Japanese Patent Laid-Open No. 6-267562. What is described in this prior document is a structure in which the porosity of the gas diffusion layer is increased from the inlet side of the gas flow path toward the outlet side. In such a configuration, the diffusion amount of gas is likely to be non-uniform within the cell surface, or the conductivity of the gas diffusion electrode is likely to decrease at the outlet side of the gas diffusion electrode, or the conductivity of the gas diffusion electrode within the cell surface. May deteriorate the basic performance of the battery, such as causing problems such as non-uniformity.

[0010]

[Patent Document 1] JP-A-6-267562

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to achieve a uniform moisture control over the entire surface of the MEA and to improve the basic performance of the gas. It is to provide a diffusion layer or a gas diffusion electrode to realize a polymer electrolyte fuel cell capable of stable operation for a long period of time.

[0012]

The gas diffusion layer of the present invention for solving the above-mentioned problems comprises a porous support, a polymer material and conductive carbon particles arranged on the porous support. A gas diffusion layer having a polymer-containing conductive layer contained therein, wherein the conductive particles are at least two kinds of conductive carbon particles having different amounts of acidic functional groups, and the conductive particles having a larger amount of the acidic functional groups. The amount of the functional carbon particles increases from one end (R2) to the other end (L2) of the gas diffusion layer.

Further, the gas diffusion layer of the present invention comprises a porous support and a polymer-containing conductive layer containing conductive carbon particles and a polymer material, which is disposed on the porous support. The polymer material is a layer, and the polymer material is at least two kinds of polymer materials having different crystallinity, and the amount of the polymer material having a lower crystallinity of the polymer materials is
It is characterized in that it increases from one end (R3) to the other end (L3) of the gas diffusion layer.

The gas diffusion layer of the present invention is a gas diffusion layer having a porous support and a polymer-containing conductive layer containing conductive carbon particles and a polymer material on the porous support. The polymer material is at least two kinds of polymer materials having different moisture permeability coefficients, and the amount of the polymer material having the larger moisture permeability coefficient among the polymer materials is equal to one end of the gas diffusion layer ( It is characterized by increasing from R4) to the other end (L4).

Further, the electrolyte membrane-electrode assembly of the present invention comprises
A polymer electrolyte membrane, a catalyst layer containing conductive carbon particles and a metal catalyst arranged on both sides of the polymer electrolyte membrane, and arranged at least one of the catalyst layer, any one of the above And a gas diffusion layer of.

Further, the polymer electrolyte fuel cell of the present invention has the above-mentioned electrolyte membrane-electrode assembly, and conductive separator plates having gas flow paths arranged on both sides of the electrolyte membrane-electrode assembly. A polymer electrolyte fuel cell comprising a stack of unit cells, wherein an oxidant gas is allowed to flow through a gas flow path of the conductive separator plate arranged with respect to the gas diffusion layer, and the gas diffusion layer. One end (R2, R3, R
4) is located at or corresponds to the inlet side of the oxidant gas, and the other ends (L2, L3, L4) are located at or correspond to the outlet side of the oxidant gas. And

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION << First Embodiment >> FIG. 2 shows the structure of a gas diffusion layer and a gas diffusion electrode (electrode 2a) using the same according to the first embodiment of the present invention from the gas diffusion layer side. It is the seen schematic diagram.

As shown in the figure, the gas diffusion layer 213a includes a porous support 21a made of carbon fibers and at least two kinds of conductive carbon particles 210a, 2a formed thereon.
It is composed of a polymer-containing conductive layer 22a composed of 11a and a polymer material 212a. In the gas diffusion layer 213a, the catalyst layer 23a made of conductive carbon particles carrying platinum is arranged on the surface of the polymer-containing conductive layer 22a to form the gas diffusion electrode 24a. The polymer-containing conductive layer 22a is
Conductive carbon particles 210 having different amounts of acidic functional groups
a, 211a are mixed, and the mixed amount of the conductive carbon particles 211a having a larger amount of acidic functional groups increases in the polymer-containing conductive layer 22a from one end (R2) to the other end (L2). ing.

Here, the acidic functional group is specifically a carbonyl group, a hydroxyl group, a quinone group or a lactone group, and
The amount of acidic functional group means the number of moles of the above-mentioned functional group per unit weight of carbon. FIG. 3 is a schematic diagram showing a gas diffusion layer and a gas diffusion electrode (electrode 2b) using the same in a conventional example. The basic structure is the same as that of the electrode 2a, but the conductive carbon particles 2 are formed in the plane of the gas diffusion layer 213b.
10b is different from the electrode 2a in that it is made of one material having the same amount of acidic functional groups (in FIG. 3, the same symbols as those in FIG. 2 are omitted).

FIG. 4 is a schematic view of a polymer electrolyte fuel cell produced using the gas diffusion electrode. In the fuel cell of this configuration, the polymer electrolyte membrane 25 has electrodes 2a on one surface and electrodes 2b on the other surface on both sides, and the catalyst layer side of each electrode is directed to the polymer electrolyte membrane side, The electrolyte membrane 25 is placed in close contact with the electrolyte membrane 25 to form an electrolyte membrane-electrode assembly (hereinafter, MEA). Further, a separator plate 27 having a gas flow path 26 formed on one surface is arranged outside the MEA, and an oxidizer is added from the gas flow path 26 of the separator plate 27 to the gas flow path indicated by the reference numeral 28 on the electrode 2a side. Air is passed as a gas, and hydrogen is passed as a fuel gas through a gas passage indicated by reference numeral 29 on the electrode 2b side. 2 is located on the inlet side of the oxidizing gas passage 28, and L2 in FIG. 2 is located on the outlet side of the oxidizing gas passage 28.

With the above-mentioned structure, uniform water content can be controlled over the entire surface of the MEA. In other words, in the gas diffusion layer on the oxidation electrode side where uniform water management was difficult due to the generation of water generated by the battery reaction, at the outlet side of the oxidant gas, the acidic functional group of the conductive particles in the gas diffusion layer was used. Since the amount of the conductive particles is large, the conductive particles are easily wetted with water, are transported along the surface of the gas diffusion layer to the vicinity of the gas channel of the separator plate, and are easily discharged to the outside of the battery via the oxidant gas. On the other hand, on the oxidant gas inlet side, the amount of acidic functional groups in the conductive particles in the gas diffusion layer is small, so that the conductive particles are less likely to be wet with water. Therefore, it is difficult for the gas to flow to the gas passage of the separator plate, and it is easy to hold the gas inside the battery.

The conductive carbon particles having different amounts of acidic functional groups in the present embodiment include a combination of acetylene black and acetylene black obtained by air-oxidizing the particles to increase the amount of acidic functional groups. Other than this, (conductive carbon material having a large amount of acidic functional group, conductive carbon material having a small amount of acidic functional group) = (furnace black, acetylene black), (furnace black, graphitized black) and the like can be mentioned.

<Second Embodiment> FIG. 5 is a schematic view of a gas diffusion layer and a gas diffusion electrode (electrode 3a) according to a second embodiment of the present invention as viewed from the gas diffusion layer side. As shown, the gas diffusion layer 313 includes a porous support 31 composed of carbon fibers, conductive carbon particles 310 formed thereon, and at least two kinds of polymer materials 311 and 31.
The polymer-containing conductive layer 32 composed of 2 is formed and configured. A catalyst layer 33 made of conductive carbon particles carrying platinum is arranged on the surface of the gas diffusion layer 313 to form a gas diffusion electrode 34.

The polymer-containing conductive layer 32 is made by mixing polymer materials 311 and 312 having different crystallinities, and the polymer material 311 having the lower crystallinity is mixed in the polymer-containing conductive layer 32 in a mixed amount. It increases from one end (R3) to the other end (L3). Since the structure of the polymer electrolyte fuel cell produced using this gas diffusion electrode is the same as that of FIG. 4, its detailed description is omitted, but R3 in FIG. 5 is located at the oxidant gas inlet side. Therefore, L3 in FIG. 5 is located on the outlet side of the oxidant gas.

With the above-mentioned structure, uniform water content can be controlled over the entire surface of the MEA. In other words, water permeation occurs because water is absorbed, diffused and permeated through the amorphous part of the polymer material, so that the polymer material in the gas diffusion layer on the outlet side of the oxidant gas has a degree of crystallinity. Since the existence ratio of the low polymer material (that is, the polymer material having many amorphous parts) increases, the amount of water permeation increases because the amorphous part of the polymer material as a whole increases, and the gas diffusion layer It is conveyed along the surface to the vicinity of the gas flow path of the separator plate, and is easily discharged to the outside of the battery via the oxidant gas. On the other hand, on the inlet side of the oxidant gas, the polymer material in the gas diffusion layer has less amorphous portion of the polymer material due to a decrease in the proportion of the material having low crystallinity. This makes it easier for the water to be retained inside the battery.

Examples of the polymer material in this embodiment include polyvinyl fluoride, polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, polyacrylonitrile, ethyl cellulose and the like. There are various materials having the same name but different crystallinity. A combination of a material having a high degree of crystallinity and a material having a low degree of crystallinity can be appropriately selected from those polymer materials and used in the present embodiment.

<< Third Embodiment >> FIG. 6 is a schematic view of a gas diffusion layer and a gas diffusion electrode (electrode 4a) according to a third embodiment of the present invention as viewed from the gas diffusion layer side.

As shown in the figure, the gas diffusion layer 413 comprises a porous support 41 composed of carbon fibers, conductive carbon particles 410 formed thereon, and at least two kinds of polymer materials 411 and 412. The polymer-containing conductive layer 42 is formed. On the surface of the gas diffusion layer 413, the catalyst layer 43 made of conductive carbon particles carrying platinum is arranged to form the gas diffusion electrode 44. Polymer-containing conductive layer 4
2 is a mixture of polymer materials 411 and 412 having different moisture permeability coefficients, and the polymer material conductive layer 42 has a mixed amount of one end (R
4) increasing from the other end (L4).

Since the structure of the polymer electrolyte fuel cell produced by using this gas diffusion electrode is the same as that of FIG. 4, its detailed description is omitted, but R4 in FIG. 4 is provided on the inlet side of the oxidant gas. L4 in FIG. 4 is located on the outlet side of the oxidizing gas.

With the above structure, uniform water content can be controlled over the entire surface of the MEA. In other words, in the gas diffusion layer on the oxidation electrode side where uniform water management was difficult because the water produced by the battery reaction was generated, on the outlet side of the oxidant gas, the polymer with a large moisture permeability coefficient was present in the gas diffusion layer. Since a large amount of the material is present, the amount of water permeation is large, the water is transmitted along the surface of the gas diffusion layer to the vicinity of the gas channel of the separator plate, and is easily discharged to the outside of the battery via the oxidant gas. On the other hand, on the inlet side of the oxidant gas, there are many polymer materials with a small moisture permeability coefficient in the gas diffusion layer, so the water permeability is small and it is difficult to carry to the gas passage of the separator plate, It becomes easy to be held in.

As a specific combination of polymer materials having different moisture permeability coefficients in the present embodiment, (polymer material having low moisture permeability coefficient, polymer material having high moisture permeability coefficient) = (PTFE, polyimide ), (PTFE, polyvinyl chloride), (PTFE, cellulose acetate), (polyethylene, polyimide), (polyethylene, polyvinyl chloride), (polyethylene, cellulose acetate), (polypropylene, polyimide), (polypropylene, polyvinyl chloride) ), (Polypropylene, cellulose acetate) and the like.

In all of the above embodiments, a carbon material is preferable as the porous support to be used, but not limited to the carbon paper used in the following examples, other carbon nonwoven fabrics may be used. Further, even if the carbon cloth is used, the effect intended by the present invention can be obtained as in the case of using the carbon paper. That is, the properties required for the porous support are that it has porosity and conductivity, and that it has a certain degree of mechanical strength as a constituent element of the gas diffusion layer.

In the embodiments of the present invention described above, it is possible to realize uniform water management over the entire MEA as described above, and to realize a polymer electrolyte fuel cell in which the voltage is stable for a long period of time. This is because the drainage of water is promoted on the outlet side of the cathode electrode as described above, and the amount of water permeation is suppressed on the contrary on the inlet side, so that the decrease in battery voltage due to drying or flooding of the polymer electrolyte membrane is suppressed. Is.

[0034]

EXAMPLES Examples of the present invention will be specifically described below. << Example 1-1 >> A. Production of Gas Diffusion Electrode Acetylene black having an average particle size of 3 μm (hereinafter referred to as AB) was heated at 400 ° C. for 10 hours in the presence of air to air-oxidize AB (hereinafter, AB subjected to the air-oxidation treatment is referred to as ABO1). ). The amount of acidic functional groups present in AB and ABO1 was measured by volatile component composition analysis.

The volatile component composition analysis utilizes the fact that when carbon is heated at about 1000 ° C. in vacuum, the acidic functional groups existing on the surface of carbon are eliminated in the form of carbon dioxide, carbon monoxide, hydrogen and methane. , A method of chemically quantifying the amount of acidic functional groups present on the surface of carbon by quantifying the gas composition (Carbon Black Handbook (3rd
Edition), edited by Carbon Black Association). A used in this example
The amount of acidic functional groups of B and ABO1 is 4.1 × 10 in AB.
^-4 mol / g, ABO1 was 9.8 × 10 ^-4 mol / g, and it was found that the amount of acidic functional groups increased in the product subjected to air oxidation treatment.

Subsequently, 10 g of AB and 2 g of a fluororesin dispersion liquid containing polytetrafluoroethylene (hereinafter referred to as PTFE) as a main component (D-1: Daikin Chemical Industry Co., Ltd.) were mixed and stirred to obtain a mixture in the fluororesin dispersion liquid. Dispersion liquid in which AB is dispersed (hereinafter referred to as dispersion liquid e1), 10 g of ABO1 and a fluororesin dispersion liquid (D-1: Daikin Chemical Industries, Ltd.) 2
g was mixed and stirred to prepare a dispersion liquid (hereinafter, referred to as dispersion liquid f1) in which ABO1 was dispersed in the fluororesin dispersion liquid.
The dispersion liquid e1 and the dispersion liquid f1 are mixed at a weight mixing ratio of
Dispersion e1: Dispersion f1 = 9: 1, 8: 2, 7: 3,
6: 4, 5: 5, 4: 6, 3: 7, 2: 8, 1: 9,
Mixed dispersions of 10 kinds d mixed at 0:10 and different in fraction
1, d2, ..., d10 were prepared.

Next, the length 3 prepared as the porous support was used.
Screen printing was performed on a carbon paper having a width of 0 cm, a width of 15 cm, and a thickness of 180 μm (manufactured by Toray Industries, Inc .: product number TGP-H-060) by a printing device whose configuration is schematically shown in FIG. 7. That is, a mask 53 having an opening 52 is arranged on the upper part of the carbon paper 51 via a support 54, and as shown in the upper part of the mask 53, the ten kinds of mixed dispersion liquids described above are dispersed in a dispersion liquid f1. From the one end (R2) to the other end (L
The dispersions d1, d2, ..., D10 were arranged toward 2) and screen printing was performed. Then, by firing at 350 ° C., a gas diffusion layer having a polymer-containing conductive layer on one surface thereof (hereinafter referred to as gas diffusion layer g1) was obtained.

The water permeability of the completed diffusion layer g1 is determined by JISZ0.
By the gravimetric method according to the example 208, it was divided into R2 portion (15 cm from one end surface of the carbon paper) and L2 portion (the remaining 15 cm portion, that is, 15 cm portion from the other end surface of the carbon paper) for evaluation. JISZ02
08 is a method of separating air having a humidity of 90% from dry air via a sample, and measuring the mass of water vapor passing through an air / sample / dry air interface 1 m ² having a humidity of 90% within 24 hours. . In this embodiment, air having a humidity of 90% is separated from dry air through a gas diffusion layer of 15 cm ² , and an air / gas diffusion layer / dry air interface having a humidity of 90% (the area of the boundary surface is 15 cm ²⁾ . Was measured for the amount of water permeating for 24 hours at 40 ° C., and was compared and evaluated with a value converted into an area of 1 m ^{2 of the} boundary surface.

The water permeation rate of the gas diffusion layer g1 is 0.8 × 10 ⁴ g / m ² · 24h at the R2 portion and 1.8 × 10 at the L2 portion.
^{At 4} g / m ² · 24 h, it was found that the amount of water permeation in the R2 part was small and that in the L2 part was large. continue,
On one surface of the polymer-containing conductive layer of the diffusion layer g1, carbon powder having a particle size of 3 μm or less was previously immersed in a chloroplatinic acid aqueous solution, and a platinum catalyst was supported on the surface of the carbon powder by a reduction treatment. (The weight ratio of carbon to supported platinum at this time was 1: 1) Carbon powder was dispersed in an alcohol solution of a polymer electrolyte, and the slurry that had been slurried was uniformly applied to form a catalyst layer. It was used as a diffusion electrode (hereinafter referred to as electrode h1).

A gas diffusion layer (hereinafter referred to as gas diffusion layer i) is formed by the same means as that used to obtain the gas diffusion layer g1 except that only the dispersion liquid e1 is used as the dispersion liquid to be printed on the entire surface of the carbon paper. Obtained. The water permeability of the diffusion layer i is 0.8
It was × 10 ⁴ g / m ² · 24 h. Subsequently, a gas diffusion electrode (hereinafter, referred to as gas diffusion electrode j) was obtained by the same operation as the above-described operation for producing the gas diffusion electrode h1 using the gas diffusion layer i.

B. Manufacture of Polymer Electrolyte Fuel Cell A gas diffusion electrode h1 and a gas diffusion electrode j of the same size are prepared, and a polymer electrolyte membrane having a size slightly larger than those of the gas diffusion electrode h1 and the gas diffusion electrode j (Dupont ) Made: N
The gas diffusion electrode h1 and the gas diffusion electrode j are superposed on both surfaces of the AFION 117) so that the surface provided with the catalyst layer faces the polymer electrolyte, and the thickness 2
After aligning a silicone rubber gasket of 50 μm on both surfaces, hot pressing was performed at 130 ° C. for 5 minutes to obtain a polymer electrolyte membrane-electrode assembly (hereinafter referred to as MEA).

Four unit cells were prepared by arranging separator plates on both sides of this MEA to form a polymer electrolyte fuel cell. A separator plate made of carbon having a thickness of 4 mm and having airtightness was used. Further, a gas channel having a width of 2 mm and a depth of 1 mm was formed by cutting on the surface in contact with the gas diffusion layer. SUS30 on the top and bottom of the battery stack
The metal end plate made of No. 4 was arranged and the polymer electrolyte fuel cell was fixed.

The gas diffusion electrode h1 was arranged so that the R2 portion thereof was on the inlet side of the gas passage of the separator plate and the L2 portion thereof was on the outlet side of the gas passage. Air is introduced from the inlet side to the outlet side of the gas passage of the separator plate on the gas diffusion electrode h1 side, and hydrogen is introduced from the inlet side to the outlet side of the gas passage of the separator plate on the gas diffusion electrode j side. Utilization rate 4
When supplied at 0% and 70% hydrogen utilization rate and operated at a hydrogen humidification bubbler temperature of 85 ° C, an air humidification bubbler temperature of 65 ° C, and a battery temperature of 75 ° C, the polymer electrolyte fuel cell has a voltage of 2.8 volts. Was generated, the initial voltage was maintained even after 3000 hours, and stable operation was exhibited. This factor is because the polymer electrolyte fuel cell of the present example was able to safely and promptly discharge excess water due to generated water while keeping the polymer electrolyte in a wet state.

Example 1-2 Except that the air-oxidized ABO1 produced in Example 1-1 was replaced as follows, the gas diffusion layer g1 produced in Example 1-1 was exactly the same. The gas diffusion layer of this example (hereinafter referred to as the gas diffusion layer g2) was produced by the production method. That is, in Example 1-1, the time for heating acetylene black (AB) having an average particle diameter of 3 μm at 400 ° C. in the presence of air was 10 hours, but the air oxidation treatment was performed for 5 hours. AB (hereinafter, this air-oxidized AB is referred to as ABO2
I got). The acidic functional group content of this ABO2 was measured by the volatile component composition analysis described in Example 1-1, and it was found to be 7.2 × 10 ⁻⁴ mol / g.

The subsequent treatment was carried out in the same manner as in Example 1-1 to prepare a dispersion liquid (hereinafter referred to as dispersion liquid f2) in which 10 g of this ABO2 was dispersed in 2 g of a fluororesin dispersion liquid, and further, Example 1-1. The dispersion liquid e1 and the dispersion liquid f2 produced in Step 10 were mixed in the same manner as in Example 1-1 with different fractions to prepare a mixed dispersion liquid of 10 types. Then, Example 1
-1, screen printing on carbon paper,
Further, the gas diffusion layer g2 was produced by firing at 350 ° C.

The water permeation rate of this gas diffusion layer g2 was determined as in Example 1-
When it was divided into R2 part and L2 part by the weight method of JISZ0208 and evaluated in the same manner as 1, the water permeability in the R2 part was 0.8 × 10 ⁴ g / m ² · 24 h, which was different from the case of Example 1-1. There was not, but 1.4 × 10 ⁴ g / in the L2 part
It was m ² · 24h. That is, the state in which the amount of water permeation in the portion R2 is small and the amount of water permeation in the portion L2 is large is in Example 1-
1 was the same as Example 1, but the water permeability in the L2 part was
It turned out that it is less than the case of -1. This is because the amount of the oxidized functional group in the L2 portion was larger than that in the R2 portion, but was smaller than that in the L2 portion in Example 1-1.

Using this gas diffusion layer g2, Example 1-
The gas diffusion electrode h2 of this example was produced by the same production method as the production of the gas diffusion electrode h1 of No. 1. This gas diffusion electrode h
Using 2 and the gas diffusion electrode j, the polymer electrolyte fuel cell of this example was produced by the same production method as that of the polymer electrolyte fuel cell of Example 1-1.

The characteristics of the polymer electrolyte fuel cell of this example were measured under the same conditions as in example 1-1. That is,
The R2 portion and the L2 portion are arranged so as to be on the inlet side and the outlet side of the gas flow path, respectively, and air is supplied to the gas diffusion electrode h2 side.
Further, hydrogen is supplied to the gas diffusion electrode j side, and the example 1-
It was operated under the same operating conditions as 1. As a result, the polymer electrolyte fuel cell of this example generates a voltage of 2.8 V,
The initial voltage was maintained even after 3000 hours, and stable operation was exhibited. This factor is because the polymer electrolyte fuel cell of the present example was able to safely and promptly discharge excess water due to generated water while keeping the polymer electrolyte in a wet state.

<Example 1-3> The gas diffusion layer g1 produced in Example 1-1 is exactly the same as the example 1 except that the air-oxidized ABO1 produced in Example 1-1 is replaced as follows. The gas diffusion layer (hereinafter, referred to as g3) of this example was manufactured by the manufacturing method. That is, in Example 1-1, acetylene black (AB) having an average particle size of 3 μm was heated at 400 ° C. for 10 hours in the presence of air.
AB subjected to air oxidation treatment at 0 ° C. for 5 hours (hereinafter,
AB subjected to this air oxidation treatment was obtained as ABO3). As a result of measuring the amount of acidic functional groups of this ABO3 by the volatile component composition analysis described in Example 1-1, it was 6.3 × 1.
It was 0 ^-4 mol / g.

After that, this ABO3 was used in Example 1.
-1 or the same process as in Example 1-2. Although the details are omitted below, since the same processing is performed, the dispersion liquid f3 is prepared in place of the dispersion liquid f1 or f2, and the dispersion liquid f is prepared.
3 was used to produce a gas diffusion layer g3 instead of the gas diffusion layer g1 or g2.

The water permeation rate of this gas diffusion layer g3 was determined as in Example 1-
When it was divided into R2 part and L2 part by the weight method of JISZ0208 and evaluated in the same manner as 1, the water permeability in the R2 part was 0.8 × 10 ⁴ g / m ² · 24 h, which was different from the case of Example 1-1. There was not, but 1.1 × 10 ⁴ g /
It was m ² · 24h. That is, the state in which the amount of water permeation in the portion R2 is small and the amount of water permeation in the portion L2 is large is in Example 1-
Although it was the same as that of Example 1 or Example 1-2, it was found that the amount of water permeation in the L2 portion was smaller than that of Example 1-2. This is because the amount of the oxidized functional group in the L2 portion was larger than that in the R2 portion, but was smaller than that in the L2 portion in Example 1-2.

Example 1-using this gas diffusion layer g3
The gas diffusion electrode h3 of this example was produced by the same production method as the production of the gas diffusion electrode h1 of No. 1. This gas diffusion electrode h
Using 3 and the gas diffusion electrode j, the polymer electrolyte fuel cell of this example was produced by the same production method as that of the polymer electrolyte fuel cell of Example 1-1.

The characteristics of the polymer electrolyte fuel cell of this example were measured under the same conditions as in example 1-1. That is,
The R2 portion and the L2 portion are arranged so as to be on the inlet side and the outlet side of the gas flow path, respectively, and air is supplied to the gas diffusion electrode h3 side.
Further, hydrogen is supplied to the gas diffusion electrode j side, and the example 1-
It was operated under the same operating conditions as 1. As a result, the polymer electrolyte fuel cell of this example generates a voltage of 2.8 V,
The initial voltage was maintained even after 3000 hours, and stable operation was exhibited. This factor is because the polymer electrolyte fuel cell of the present example was able to safely and promptly discharge excess water due to generated water while keeping the polymer electrolyte in a wet state.

<< Example 1-4 >> A used in Example 1-1
B and the air-oxidized ABO1 were replaced as follows, except that the gas diffusion layer g1 produced in Example 1-1 was manufactured by exactly the same production method as the gas diffusion layer (hereinafter, g
4) was produced. That is, first, in Example 1-1, acetylene black (AB) having an average particle size of 3 μm and A
Although BO1 was used, in this example, instead of this, graphitized black (hereinafter referred to as GB) having an average particle size of 3 μm and furnace black (hereinafter referred to as FB) having an average particle size of 3 μm were used. The amounts of these acidic functional groups of GB and FB were measured by the volatile component composition analysis described in Example 1-1, and as a result, they were 0.2 × 10 ^-4 mol / g and 5.7, respectively.
It was × 10 ^-4 mol / g.

After that, the combination of GB and FB was changed to AB and ABO1 of Example 1-1 and Example 1 respectively.
-2 AB and ABO2, Example 1-3 AB and ABO3
Was used in place of each combination of and the same processing as in each example was performed. Although the details are omitted below because they are similar treatments, the dispersion e2 is prepared in place of the dispersion e1, the dispersion f4 is prepared in place of the dispersions f1, f2, or f3. Gas diffusion layer g using dispersion f4
A gas diffusion layer g4 was prepared in place of 1, g2 or g3.

The amount of water permeation of this gas diffusion layer g4 was determined as in Example 1-
In the same way as in No. 1, the weight method of JIS Z0208 was divided into R2 part and L2 part for evaluation, and the water permeation rate in the R2 part was 0.1 × 10 ⁴ g / m ² · 24 h, which was compared with the case of Example 1-1. It has decreased by almost one digit, but it is 0.9 in the L2 part.
It was × 10 ⁴ g / m ² · 24 h. That is, the state in which the amount of water permeation in the R2 portion was small and the amount of water permeation in the L2 portion was large was similar to the examples of the former three, but the amount of water permeation in the R2 portion and the L2 portion was smaller than that of the former three. , On the other hand, R
The difference between the amount of water permeation in part 2 and the amount of water permeation in part L2 is 3
It turns out that it is larger than the case of the person. This means that the amount of oxidized functional groups in the R2 portion and the L2 portion was smaller than those in the former three, respectively, while the R2 portion and the L2 portion were
This is because the difference in the amount of oxidized functional groups in the two parts was larger than that in the former three cases.

Using this gas diffusion layer g4, Example 1-
The gas diffusion electrode h4 of this example was produced by the same production method as the production of the gas diffusion electrode h1 of No. 1. This gas diffusion electrode h
Using 4 and the gas diffusion electrode j, the polymer electrolyte fuel cell of this example was produced by the same production method as that of the polymer electrolyte fuel cell of Example 1-1.

The characteristics of the polymer electrolyte fuel cell of this example were measured under the same conditions as in example 1-1. That is,
The R2 portion and the L2 portion are arranged so that they are on the inlet side and the outlet side of the gas flow path, respectively, and air is supplied to the gas diffusion electrode h4 side.
Further, hydrogen is supplied to the gas diffusion electrode j side, and the example 1-
It was operated under the same operating conditions as 1. As a result, the polymer electrolyte fuel cell of this example generates a voltage of 2.8 V,
The initial voltage was maintained even after 3000 hours, and stable operation was exhibited. This factor is because the polymer electrolyte fuel cell of the present example was able to safely and promptly discharge excess water due to generated water while keeping the polymer electrolyte in a wet state.

In the above Examples 1-1 to 1-4, the mixing ratio of two kinds of materials having different acidic functional groups was set to 10%.
Although the mixture was divided and used, the mixing ratio is not limited to this, and one having a small amount of acidic functional groups and one having a large amount of acidic functional groups, 0.2 × 10 ⁻⁴ mol / mol, as exemplified in the examples. g ~
9.8 × 10 ⁻⁴ mol / g is appropriately selected and mixed, and as a result, the amount of the acidic functional group increases from the R2 portion to the L2 portion, and more preferably, gradually increases. If so, it was also confirmed that the same effect as that obtained in the above-mentioned example group could be obtained. Further, in the above-mentioned group of examples, a combination of two kinds of carbon particles having different amounts of acidic functional groups was exemplified, but even in a combination of three or more kinds, the amount of acidic functional groups increases from the R2 portion toward the L2 portion. It was also confirmed separately that similar good results could be obtained.

<< Example 2-1 >> A. Production of Gas Diffusion Electrode 10 g of AB used in Example 1-1 was used as a main component, and PTFE having a lower crystallinity and a different molecular weight than PTFE, which is the main component of D-1 described in Example 1-1. Fluorine resin dispersion liquid (manufactured by Daikin Chemical Industries, Ltd .: Lubron) 2 g
Was mixed and stirred to prepare a dispersion liquid (hereinafter, referred to as dispersion liquid k1) in which AB was dispersed in the fluororesin dispersion liquid Lubron, and then the dispersion liquid e1 and the dispersion liquid k1 described in Example 1-1 were mixed by weight. And dispersion e1: dispersion k1 = 9: 1,
8: 2, 7: 3, 6: 4, 5: 5, 4: 6, 3: 7,
Mixing at 2: 8, 1: 9, 0:10 with different fractions 10
A mixed dispersion of seeds was prepared.

Here, the crystallinity is the volume% of the crystallized portion in the total amount of the crystallized portion and the amorphous portion, and can be measured by the X-ray measuring method. As a result of the measurement by the X-ray measurement method, the crystallinity of PTFE in the D-1 dispersion was 80%, and the crystallinity of PTFE in the Lubron dispersion was 40%.

Next, the length 3 prepared as the porous support was used.
The mixing ratio of the dispersion liquid k1 was from the one end (R3) to the other end (L3) on the surface of 0 cm, width 15 cm, and thickness 180 μm carbon paper (manufactured by Toray Industries, Inc .: product number TGP-H-060). In order to increase the amount, the above 10 kinds of mixed dispersion liquids are added by the same means as described in Example 1-1,
Screen printing was performed. Then, it baked at 350 degreeC and the gas diffusion layer (henceforth gas diffusion layer m1) was obtained.

The amount of water permeation of the gas diffusion layer m1 completed in this way is determined by the R3 portion (15 cm from one end surface of the carbon paper).
Part) and L3 part (1 from the other end surface of carbon paper)
It was divided into 5 cm portions) and evaluated by the weight method of JIS Z0208. Water permeability was 0.8 × 1 at the R3 portion.
0 ⁴ g / m ² · 24h, L3 part 1.8 × 10 ⁴ g / m ² ·
At 24 hours, it was found that the water permeability was low in the R3 part and increased in the L3 part.

Subsequently, on one surface of the gas diffusion layer m1, carbon powder having a particle size of 3 μm or less was previously immersed in an aqueous solution of chloroplatinic acid, and a platinum catalyst was carried on the surface of the carbon powder by reduction treatment (this (The weight ratio of carbon to supported platinum at this time was 1: 1) Carbon powder was dispersed in an alcohol solution of a polymer electrolyte, and the slurry that had been slurried was uniformly applied to form a catalyst layer. It was used as a diffusion electrode (hereinafter referred to as gas diffusion electrode n1).

B. Manufacture of polymer electrolyte fuel cell: A gas diffusion electrode n1 having the same size and the gas diffusion electrode j prepared in Example 1-1 are prepared, and the outer dimensions are slightly larger than those of the gas diffusion electrode n1 and the gas diffusion electrode j. A gas diffusion electrode n1 and a gas diffusion electrode j were superposed on both surfaces of a polymer electrolyte membrane (NAFION 117 manufactured by DuPont Co., Ltd.) such that the surfaces each provided with a catalyst layer face the polymer electrolyte, and the thickness was further increased. After aligning 250μm silicone rubber gaskets on both sides,
It hot-pressed at 5 degreeC for 5 minutes, and obtained MEA.

Four unit cells were prepared by arranging separator plates on both sides of this MEA to obtain a polymer electrolyte fuel cell. A separator plate made of carbon having a thickness of 4 mm and having airtightness was used. Further, a gas channel having a width of 2 mm and a depth of 1 mm was formed by cutting on the surface in contact with the gas diffusion layer. SUS30 on the top and bottom of the battery stack
The metal end plate made of No. 4 was arranged and the polymer electrolyte fuel cell was fixed.

The gas diffusion electrode n1 was arranged such that the R3 portion thereof was on the inlet side of the gas passage of the separator plate and the L3 portion thereof was on the outlet side of the gas passage. Air from the inlet side to the outlet side of the gas passage of the separator plate on the electrode n1 side, hydrogen from the inlet side to the outlet side of the gas passage of the separator plate on the electrode j side, and an oxygen utilization rate of 40% , With hydrogen utilization rate of 70%, supply respectively, hydrogen humidification bubbler temperature 85 ℃, air humidification bubbler temperature 65 ℃, battery temperature 75 ℃
As a result, the polymer electrolyte fuel cell generated a voltage of 2.8 V, maintained the initial voltage even after 3000 hours had elapsed, and showed stable operation. This is because the polymer electrolyte fuel cell of this example was able to safely and promptly discharge excess water due to generated water while keeping the polymer electrolyte in a wet state.

Example 2-2 Dispersion e in Example 2-1
Fluororesin dispersion D containing PTFE as a main component used in No. 1
A dispersion liquid e3 was prepared in place of the dispersion liquid e1 by using a dispersion liquid (polypropylene / ethanol weight ratio in this dispersion liquid was 20:80) in which polypropylene having a crystallinity of 80% was dispersed in place of -1. In addition to the fluororesin dispersion containing PTFE as a main component used in the dispersion k1, a dispersion liquid in which polypropylene having a crystallinity of 40% was dispersed in ethanol (the weight of polypropylene and ethanol in this dispersion liquid) was used. The ratio is also 20:80) and dispersion k2 is used instead of dispersion k1.
A gas diffusion layer (hereinafter, referred to as gas diffusion layer m2) of this example was produced by the same production method as that of the gas diffusion layer m1 produced in Example 2-1 except that the above was produced.

That is, the dispersion liquid e3 and the dispersion liquid k2 were mixed with 10 kinds having different fractions in the same manner as in Example 2-1 to prepare a mixed dispersion liquid of 10 kinds. Then, Example 2
-1, screen printing on carbon paper,
Further, by firing at 350 ° C., the gas diffusion layer m2 of this example was produced.

The amount of water permeation of this gas diffusion layer m2 was measured in Example 2-
The water permeability was 0.8 × 10 ⁴ g / m ² · 24h at the R3 portion and 1.8 × at the L3 portion when evaluated by dividing it into the R3 portion and the L3 portion by the weight method of JISZ0208 as in 1.
At 10 ⁴ g / m ² · 24 h, there was no change from the case of Example 2-1. This is due to the crystallinity of the R2 part and L
This is because both of the two parts were the same as in Example 2-1.

Example 2-using this gas diffusion layer m2
The gas diffusion electrode n2 of this example was produced by the same production method as that of the gas diffusion electrode n1 of No. 1. This gas diffusion electrode n
Using 2 and the gas diffusion electrode j, the polymer electrolyte fuel cell of this example was produced by the same production method as that of the polymer electrolyte fuel cell of Example 2-1.

The characteristics of the polymer electrolyte fuel cell of this example were measured under the same conditions as in example 2-1. That is,
The R3 portion and the L3 portion are arranged so as to be on the inlet side and the outlet side of the gas flow path, respectively, and air is supplied to the gas diffusion electrode n2 side.
Further, hydrogen is supplied to the gas diffusion electrode j side, and Example 2-
It was operated under the same operating conditions as 1. As a result, the polymer electrolyte fuel cell of this example generates a voltage of 2.8 V,
The initial voltage was maintained even after 3000 hours, and stable operation was exhibited. This factor is because the polymer electrolyte fuel cell of the present example was able to safely and promptly discharge excess water due to generated water while keeping the polymer electrolyte in a wet state.

Example 2-3 Dispersion e in Example 2-1
Fluororesin dispersion D containing PTFE as a main component used in No. 1
A dispersion liquid e4 was prepared in place of the dispersion liquid e1 by using a dispersion liquid in which polyethylene having a crystallinity of 80% was dispersed in ethanol instead of -1 (the weight ratio of polyethylene to ethanol in this dispersion liquid was 20:80). What you did, and
Dispersion was performed using an ethanol solution of acrylonitrile with a crystallinity of 30% (the weight ratio of acrylonitrile and ethanol in this solution is also 20:80) instead of the fluororesin dispersion liquid Lubron containing PTFE as the main component used in the dispersion liquid k1. The gas diffusion layer (hereinafter referred to as gas diffusion layer m3) of this example was manufactured by the same production method as that of the gas diffusion layer m1 produced in Example 2-1 except that the dispersion liquid k3 was produced instead of the liquid k1. ) Was produced. Note that the polymer-containing conductive layer was formed by baking at 350 ° C. in the process of manufacturing the gas diffusion layer.

The amount of water permeation of this gas diffusion layer m3 was determined in Example 2-
As in the case of 1, the evaluation was made by dividing into R3 part and L3 part by the weight method of JIS Z0208, and the water permeability in the R3 part was 0.8 × 10 ⁴ g / m ² · 24 h, which was different from that in Example 2-1. There was not, but in the L3 part 2.0 × 10 ⁴ g /
It was m ² · 24h. That is, the state in which the amount of water permeation in the portion R3 is small and the amount of water permeation in the portion L3 is large is in Example 2-
Although it was the same as that of Example 1 or Example 2-2, it was found that the amount of water permeation at the L3 portion was larger than that of the former two examples. This is because the crystallinity was higher than the L3 portion of the former two examples.

Example 2-using this gas diffusion layer m3
The gas diffusion electrode n3 of this example was produced by the same production method as that of the gas diffusion electrode n1 of No. 1. This gas diffusion electrode n
Using 3 and the gas diffusion electrode j, the polymer electrolyte fuel cell of this example was produced by the same production method as that of the polymer electrolyte fuel cell of Example 2-1.

The characteristics of the polymer electrolyte fuel cell of this example were measured under the same conditions as in example 2-1. That is,
The R3 part and the L3 part are arranged so as to be on the inlet side and the outlet side of the gas flow path, respectively, and air is supplied to the gas diffusion electrode n3 side.
Further, hydrogen is supplied to the gas diffusion electrode j side, and Example 2-
It was operated under the same operating conditions as 1. As a result, the polymer electrolyte fuel cell of this example generates a voltage of 2.8 V,
The initial voltage was maintained even after 3000 hours, and stable operation was exhibited. This factor is because the polymer electrolyte fuel cell of the present example was able to safely and promptly discharge excess water due to generated water while keeping the polymer electrolyte in a wet state.

Example 2-4 Dispersion e in Example 2-1
Instead of the fluororesin dispersion containing PTFE as the main component used in Example 1, a m-cresol solution of polyethylene terephthalate having a crystallinity of 60% (the weight ratio of polyethylene terephthalate and m-cresol in this solution was 20: 8).
0) was used to prepare a dispersion e5 instead of the dispersion e1, and the fluororesin dispersion Lubron used in the dispersion k1 was replaced with an ethanol solution of vinyl chloride having a crystallinity of 10% (in this solution). A gas diffusion layer m1, m2 or m3 prepared in the former three examples except that a dispersion k4 was prepared in place of the dispersion k1 by using a vinyl chloride / ethanol weight ratio of 20:80). The gas diffusion layer of the present example (hereinafter referred to as the gas diffusion layer m4) was produced by exactly the same production method. Note that the polymer-containing conductive layer was formed by baking at 350 ° C. in the process of manufacturing the gas diffusion layer.

The amount of water permeation of this gas diffusion layer m4 was measured in Example 2-
The water permeability of the R3 portion was 1.2 × 10 ⁴ g / m ² · 24h, which was evaluated by dividing it into the R3 portion and the L3 portion by the weight method of JIS Z0208 in the same manner as in 1. Was also increased, but 2.8 × 10 in the L3 part
^{It was 4} g / m ² · 24 h, which was higher than in the cases of the former three cases. This is because the crystallinity was higher in the R3 portion and the L3 portion than in the former three examples.

Example 2-using this gas diffusion layer m4
The gas diffusion electrode n4 of this example was produced by the same production method as that of the gas diffusion electrode n1 of No. 1. This gas diffusion electrode n
Using 4 and the gas diffusion electrode j, a polymer electrolyte fuel cell of this example was produced by the same production method as that of the polymer electrolyte fuel cell of Example 2-1.

The characteristics of the polymer electrolyte fuel cell of this example were measured under the same conditions as in example 2-1. That is,
The R3 portion and the L3 portion are arranged so as to be on the inlet side and the outlet side of the gas flow path, respectively, and air is supplied to the gas diffusion electrode n4 side.
Further, hydrogen is supplied to the gas diffusion electrode j side, and Example 2-
It was operated under the same operating conditions as 1. As a result, the polymer electrolyte fuel cell of this example generates a voltage of 2.8 V,
The initial voltage was maintained even after 3000 hours, and stable operation was exhibited. This factor is because the polymer electrolyte fuel cell of the present example was able to safely and promptly discharge excess water due to generated water while keeping the polymer electrolyte in a wet state.

In Examples 2-1 to 2-4, the mixing ratio of two kinds of materials having different crystallinity was divided into 10 parts, but the mixing ratio is not limited to this. , Those having high and low crystallinity, and those exemplified in the examples, 80% to 10% are appropriately selected and mixed, and as a result, crystals are crystallized from the R3 portion toward the L3 portion. It was also confirmed that the same effect as that obtained in the above-mentioned group of examples can be obtained if the constitution is such that the degree of chemical conversion decreases, more preferably the constitution gradually decreases. Further, in the above-mentioned group of examples, a combination of two kinds of polymer materials having different crystallinities was exemplified, but even in a combination of three or more kinds, from the R3 part to the L3 part.
It was also separately confirmed that good results could be obtained if the crystallinity decreased toward the portion.

Example 3-1 A. Production of Gas Diffusion Electrode 10 g of AB used in Example 1-1 and N-methyl-2-pyrrolidone containing polyimide resin as a main component as a resin having a larger moisture permeability coefficient than PTFE described in Example 1-1. 2 g of a solution (JALS214, manufactured by Japan Synthetic Rubber Co., Ltd.) was mixed and stirred to obtain a dispersion liquid (hereinafter, referred to as dispersion liquid p1) in which AB was dispersed in an N-methyl-2-pyrrolidone solution containing a polyimide resin as a main component. Prepared. Then, Example 1
The dispersion liquid e1 and the dispersion liquid p1 described in -1 are mixed at a weight mixing ratio of dispersion liquid e1: dispersion liquid p1 = 9: 1, 8: 2, 7:
3, 6: 4, 5: 5, 4: 6, 3: 7, 2: 8, 1:
Mixing was carried out at 9, 0:10 to prepare 10 kinds of mixed dispersion liquids having different fractions.

Here, the moisture permeability coefficient is the moisture permeability in a unit area, a unit time, and a constant atmospheric pressure, and here, the definition based on Japanese Industrial Standard JIS-A9511 is used. As a result of the measurement, the moisture permeability coefficient of PTFE in the dispersion liquid e1 is 0.01 g / m · hr · mmHg, and the moisture permeability coefficient of the polyimide resin in the dispersion liquid p1 is 0.04 g / m · hr · mm.
It was Hg.

Next, the length 3 prepared as the porous support was used.
The mixing ratio of the dispersion liquid p1 was from the one end (R4) to the other end (L4) on the surface of 0 cm, width 15 cm, and thickness 180 μm carbon paper (manufactured by Toray Industries, Inc .: product number TGP-H-060). Arrange so that there are many, 10 above
The mixed dispersion of the seeds was screen printed by the same means as described in Example 1-1. Then, it baked at 350 degreeC and the gas diffusion layer (henceforth gas diffusion layer q1) was obtained.

The amount of water permeation of the gas diffusion layer q1 completed in this way was adjusted to R4 (15 cm from one end of carbon paper) and L4 (15 cm from the other end of carbon paper).
cm part) and evaluated by the weight method of JIS Z0208, the water permeability is 0.8 × 10 ^{4 in the} R4 part.
g / m ² · 24h, L4 part 1.8 × 10 ⁴ g / m ² · 24
At h, it was found that the amount of water permeation was small in the portion R4 and was large in the portion L4.

Subsequently, on one surface of the gas diffusion layer q1, carbon powder having a particle size of 3 μm or less was previously immersed in a chloroplatinic acid aqueous solution, and a platinum catalyst was carried on the surface of the carbon powder by reduction treatment (this (The weight ratio of carbon to supported platinum at this time was 1: 1) Carbon powder was dispersed in an alcohol solution of a polymer electrolyte, and the slurry that had been slurried was uniformly applied to form a catalyst layer. It was used as a diffusion electrode (hereinafter referred to as gas diffusion electrode r1).

B. Manufacture of polymer electrolyte fuel cell: A gas diffusion electrode r1 of the same size and the gas diffusion electrode j prepared in Example 1-1 are prepared, and the outer dimensions are slightly larger than those of the gas diffusion electrode r1 and the gas diffusion electrode j. On both sides of the polymer electrolyte membrane (DuPont KK; NAFION 117),
The gas diffusion electrode r1 and the gas diffusion electrode j were superposed such that the surfaces provided with the catalyst layers face the polymer electrolyte, respectively, and further, a silicone rubber gasket having a thickness of 250 μm was aligned on both surfaces, and then at 130 ° C. 5
After hot pressing for a minute, MEA was obtained.

Four unit cells were prepared by arranging separator plates on both sides of this MEA to obtain a polymer electrolyte fuel cell. A separator plate made of carbon having a thickness of 4 mm and having airtightness was used. Further, a gas channel having a width of 2 mm and a depth of 1 mm was formed by cutting on the surface in contact with the gas diffusion layer. SUS30 on the top and bottom of the battery stack
The metal end plate made of No. 4 was arranged and the polymer electrolyte fuel cell was fixed.

The gas diffusion electrode r1 was arranged such that the R4 portion thereof was on the inlet side of the gas passage of the separator plate and the L4 portion thereof was on the outlet side of the gas passage. The gas utilization of the separator plate on the gas diffusion electrode r1 side is air from the inlet side to the outlet side, and the gas passage of the separator plate on the electrode j side is hydrogen from the inlet side to the outlet side. 40%,
When hydrogen was supplied at a hydrogen utilization rate of 70% and operated at a hydrogen humidification bubbler temperature of 85 ° C, an air humidification bubbler temperature of 65 ° C, and a cell temperature of 75 ° C, the polymer electrolyte fuel cell generated a voltage of 2.8 volts. The initial voltage was maintained even after 3000 hours, and stable operation was exhibited. This is because the polymer electrolyte fuel cell of this example was able to safely and promptly discharge excess water due to generated water while keeping the polymer electrolyte in a wet state.

Example 3-2 Instead of the N-methyl-2-pyrrolidone solution containing polyimide resin as the main component used in the dispersion p1 in Example 3-1, the moisture permeability coefficient was 0.1.
A dispersion p2 was prepared in place of the dispersion p1 using an ethanol dispersion of polyvinyl chloride of g / m · hr · mmHg% (the weight ratio of polyvinyl chloride and ethanol in this dispersion was 20:80). Except for the above, Example 3-1
The gas diffusion layer of the present example (hereinafter referred to as the gas diffusion layer q2) was produced by the same production method as that of the gas diffusion layer q1 produced in the above.

The water permeation rate of this gas diffusion layer q2 was determined as in Example 3-
When the water resistance was 0.8 × 10 ⁴ g / m ² · 24h in the R4 part, the water permeation rate was 0.8 × 10 ⁴ g / m ² · 24h, which was evaluated by dividing it into the R4 part and the L4 part by the weight method of JIS Z0208 as in the case of Example 3-1. However, in the L4 part, 2.3 × 10 ⁴ g / m ²
-At 24 hours, the number was higher than that in Example 3-1.
Regarding the moisture permeability coefficient, this is L compared to Example 3-1.
This is because it was larger in the 4th part.

Example 3-using this gas diffusion layer q2
The gas diffusion electrode r2 of this example was produced by the same production method as the production of the gas diffusion electrode r1 of No. 1. This gas diffusion electrode r
Using 2 and the gas diffusion electrode j, the polymer electrolyte fuel cell of this example was produced by the same production method as that of the polymer electrolyte fuel cell of Example 3-1.

The characteristics of the polymer electrolyte fuel cell of this example were measured under the same conditions as in example 3-1. That is,
The R4 portion and the L4 portion are arranged so as to be on the inlet side and the outlet side of the gas flow path, respectively, and air is supplied to the gas diffusion electrode r2 side.
Furthermore, hydrogen is supplied to the gas diffusion electrode j side, and Example 3-
It was operated under the same operating conditions as 1. As a result, the polymer electrolyte fuel cell of this example generates a voltage of 2.8 V,
The initial voltage was maintained even after 3000 hours, and stable operation was exhibited. This factor is because the polymer electrolyte fuel cell of the present example was able to safely and promptly discharge excess water due to generated water while keeping the polymer electrolyte in a wet state.

<< Example 3-3 >> Dispersion e in Example 3-1.
Fluororesin dispersion D containing PTFE as a main component used in No. 1
-1 instead of -1 moisture permeability coefficient 0.01g / m ・ hr ・ mm
Example 3 except that a dispersion liquid e3 was prepared instead of the dispersion liquid e1 using a dispersion liquid in which Hg% polypropylene was dispersed in ethanol (the weight ratio of polypropylene to ethanol in this dispersion liquid was 20:80). A gas diffusion layer of this example (hereinafter referred to as gas diffusion layer q3) was produced by the same production method as that of the gas diffusion layer q1 produced in -1.

The amount of water permeation of this gas diffusion layer q3 was determined as in Example 3-
The water permeability was 0.8 × 10 ⁴ g / m ² · 24h for the R4 part and 1.8 for the L4 part when evaluated by dividing into R4 part and L4 part by the weight method of JISZ0208 as in 1.
It was × 10 ⁴ g / m ² · 24 h, which was the same as in the case of Example 3-1. This is because, although the materials used were different, the R4 portion and the L4 portion had the same moisture permeability coefficient as in Example 3-1.

Example 3-using this gas diffusion layer q3
The gas diffusion electrode r3 of this example was produced by the same production method as that of the gas diffusion electrode r1 of No. 1. This gas diffusion electrode r
Using 3 and the gas diffusion electrode j, the polymer electrolyte fuel cell of this example was produced by the same production method as that of the polymer electrolyte fuel cell of Example 3-1.

The characteristics of the polymer electrolyte fuel cell of this example were measured under the same conditions as in example 3-1. That is,
The R4 part and the L4 part are arranged so as to be on the inlet side and the outlet side of the gas flow path, respectively, and air is supplied to the gas diffusion electrode r3 side.
Furthermore, hydrogen is supplied to the gas diffusion electrode j side, and Example 3-
It was operated under the same operating conditions as 1. As a result, the polymer electrolyte fuel cell of this example generates a voltage of 2.8 V,
The initial voltage was maintained even after 3000 hours, and stable operation was exhibited. This factor is because the polymer electrolyte fuel cell of the present example was able to safely and promptly discharge excess water due to generated water while keeping the polymer electrolyte in a wet state.

Example 3-4 Dispersion e in Example 3-1
Fluororesin dispersion D containing PTFE as a main component used in No. 1
-1 instead of -1 moisture permeability coefficient 0.01g / m ・ hr ・ mm
Dispersion e4 was prepared in place of Dispersion e1 using a dispersion in which Hg% polyethylene was dispersed in ethanol (the weight ratio of polyethylene to ethanol in this dispersion was 20:80), and Dispersion p1 Instead of the N-methyl-2-pyrrolidone solution containing polyimide resin as the main component used in the above, a moisture permeability coefficient of 0.1 g / m · hr · mmH
g% cellulose acetate in ethanol (the weight ratio of cellulose acetate to ethanol in this solution is 20: 8)
0) was used to prepare the dispersion p3 instead of the dispersion p1, and the gas diffusion layer q1 prepared in Example 3-1.
A gas diffusion layer of the present example (hereinafter referred to as gas diffusion layer q4) was produced by the same production method as described above.

The amount of water permeation of this gas diffusion layer q4 was determined as in Example 3-
As in the case of 1, the evaluation was made by dividing into R4 part and L4 part by the weight method of JIS Z0208, and the water permeability in the R4 part was 0.8 × 10 ⁴ g / m ² · 24h, which was the same as the case of the former three cases. Same, but 2.3 × 10 ⁴ g / L4
m ² · 24h, the same as in Example 3-2. Although the materials used were different, the R4 part was the same as the former three with respect to the moisture permeability coefficient, and the L4 part was the same as Example 3-2.
It was because it was the same as the case.

Example 3-using this gas diffusion layer q4
The gas diffusion electrode r4 of this example was produced by the same production method as that of the gas diffusion electrode r1 of No. 1. This gas diffusion electrode r
Using 4 and the gas diffusion electrode j, the polymer electrolyte fuel cell of this example was produced by the same production method as that of the polymer electrolyte fuel cell of Example 3-1.

The characteristics of the polymer electrolyte fuel cell of this example were measured under the same conditions as in example 3-1. That is,
The R4 portion and the L4 portion are arranged so as to be on the inlet side and the outlet side of the gas flow path, respectively, and air is supplied to the gas diffusion electrode r4 side.
Furthermore, hydrogen is supplied to the gas diffusion electrode j side, and Example 3-
It was operated under the same operating conditions as 1. As a result, the polymer electrolyte fuel cell of this example generates a voltage of 2.8 V,
The initial voltage was maintained even after 3000 hours, and stable operation was exhibited. This factor is because the polymer electrolyte fuel cell of the present example was able to safely and promptly discharge excess water due to generated water while keeping the polymer electrolyte in a wet state.

In the above Examples 3-1 to 3-4, the mixing ratio of two kinds of materials having different water vapor transmission coefficients was divided into 10 and used, but the mixing ratio is not limited to this. The one having a small moisture permeability and the one having a large moisture permeability are 0.8 × 10 ⁴ g / m ² · 24h or more.
2.3 × 10 ⁴ g / m ² · 24 h, which is appropriately selected and mixed, and as a result, the moisture permeability coefficient increases from the R4 portion to the L4 portion, and more preferably, gradually increases. If so, it was also confirmed that the same effect as that obtained in the above-mentioned example group could be obtained. Further, in the above-mentioned group of examples, a combination of two kinds of polymer materials having different water vapor transmission coefficients was exemplified, but even in a combination of three or more kinds, the water vapor transmission coefficient increases from the R4 portion to the L4 portion. It was also confirmed separately that similar good results could be obtained.

Comparative Example A polymer electrolyte fuel cell was prepared in the same manner as described in the above-mentioned group of examples except that the gas diffusion electrode j was used for both of the two gas diffusion electrodes that sandwich the MEA. When the polymer electrolyte fuel cell thus completed was operated under the same conditions as those described in the above example group, the initial voltage was 2.8 V, which was the same as in the case of the above example group, but the voltage gradually decreased. However, the voltage after 3000 hours had dropped to 1.8 V, and the operation was very unstable. The reason for this is that in the polymer electrolyte fuel cell of this comparative example, the water management inside the MEA is insufficient, and the polymer electrolyte membrane is dried at the inlet side or gas diffusion is hindered by flooding at the outlet side. It is due to the fact.

[0104]

INDUSTRIAL APPLICABILITY As described above, in the gas diffusion layer, the porous support and at least two types of conductive carbon particles having different acidic functional groups and the polymer-containing conductive layer composed of the polymer material are used as the gas diffusion layer. Of the two types of conductive carbon particles, the ratio of the conductive carbon particles having the larger number of acidic functional groups to the total amount of conductive particles is increased from one end of the gas diffusion electrode to the other end. The water permeation function in the plane of the gas diffusion layer can be adjusted by the method, the polymer electrolyte can be kept in a wet state in the MEA, and excess water due to the produced water can be quickly drained. Further, by forming a gas diffusion electrode using the gas diffusion layer and manufacturing a polymer electrolyte fuel cell, a polymer electrolyte fuel cell that exhibits stable operation over a long period of time can be realized.

In the gas diffusion layer, a porous support, a conductive carbon particle, and a polymer-containing conductive layer composed of at least two polymer materials having different crystallinities are used. By increasing the ratio of the polymer material having the lower crystallinity to the total polymer material amount from one end of the gas diffusion electrode to the other end, the water permeation function in the plane of the gas diffusion layer can be adjusted. While keeping the polymer electrolyte in a wet state, excess water due to generated water can be quickly drained. Further, by using the above-mentioned gas diffusion layer to form a gas diffusion electrode and manufacturing a polymer electrolyte fuel cell, it is possible to realize a polymer electrolyte fuel cell that exhibits stable operation over a long period of time.

In the gas diffusion layer, a porous support, a conductive carbon particle, and a polymer-containing conductive layer composed of at least two kinds of polymer materials having different moisture permeability coefficients are used. By increasing the ratio of the polymer material having the higher moisture permeability to the total amount of the polymer material from one end of the gas diffusion electrode to the other end, the water permeability function in the plane of the gas diffusion layer can be adjusted. While keeping the polymer electrolyte in a wet state, excess water due to generated water can be quickly drained. Further, by using the gas diffusion layer to form a gas diffusion electrode and manufacturing a polymer electrolyte fuel cell, a polymer electrolyte fuel cell that exhibits stable operation over a long period of time can be realized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing the configuration of a conventional polymer electrolyte fuel cell.

FIG. 2 is a partial cross-sectional perspective view schematically showing an outline of a gas diffusion layer and a gas diffusion electrode in the first embodiment.

FIG. 3 is a partial cross-sectional perspective view schematically showing an outline of a conventional gas diffusion layer and a gas diffusion electrode.

FIG. 4 is a cross-sectional view schematically showing the outline of the polymer electrolyte fuel cell according to the first embodiment.
FIG. 3 is a diagram common to the outline of the polymer electrolyte fuel cell of the embodiment.

FIG. 5 is a partial cross-sectional perspective view schematically showing an outline of a gas diffusion layer and a gas diffusion electrode in the second embodiment.

FIG. 6 is a partial cross-sectional perspective view schematically showing an outline of a gas diffusion layer and a gas diffusion electrode according to a third embodiment.

FIG. 7 is a perspective view schematically showing the outline of the configuration of a printing apparatus for applying the constituent dispersion liquid of the gas diffusion layer to the surface of the porous support by screen printing.

[Explanation of symbols]

11 Polymer electrolyte membrane 12 Catalyst layer 13 Gas diffusion layer 14 Gas diffusion electrode 15 Electrolyte Membrane-Electrode Assembly 16 gas flow paths 17 Separator plate 18 gasket 21a Porous support 22a Polymer-containing conductive layer 23a catalyst layer 24a gas diffusion electrode 25 Polymer electrolyte membrane 26 gas flow paths 27 Separator plate 28 Oxidant gas flow path 29 Fuel gas flow path 210a, 210b conductive carbon particles 211a conductive carbon particles 212a Polymer material 213a, 213b Gas diffusion layer 31 porous support 32 Polymer-containing conductive layer 33 catalyst layer 34 Gas diffusion electrode 310 conductive carbon particles 311 polymeric materials 312 Polymer material 313 Gas diffusion layer 41 porous support 42 polymer-containing conductive layer 43 catalyst layer 44 Gas diffusion electrode 410 conductive carbon particles 411 Polymer material 412 Polymer material 413 gas diffusion layer 51 carbon paper 52 opening 53 masks 54 Support

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Claims (5)

[Claims] 1. A gas diffusion layer having a porous support and a polymer-containing conductive layer containing a polymer material and conductive carbon particles disposed on the porous support, the conductive layer comprising: The carbon particles are at least two kinds of conductive carbon particles having different amounts of acidic functional groups, and the amount of the conductive carbon particles having the larger amount of acidic functional groups varies from one end (R2) to the other end of the gas diffusion layer. A gas diffusion layer for a polymer electrolyte fuel cell, wherein the gas diffusion layer is increasing toward (L2). 2. A gas diffusion layer having a porous support and a polymer-containing conductive layer containing conductive carbon particles and a polymer material disposed on the porous support, the polymer comprising The material is at least two kinds of polymer materials having different crystallinity, and the amount of the polymer material having the lower crystallinity is higher than that of the gas diffusion layer from one end (R3) to the other end. A gas diffusion layer for a polymer electrolyte fuel cell, characterized by increasing toward (L3). 3. A gas diffusion layer having a porous support and a polymer-containing conductive layer containing conductive carbon particles and a polymer material on the porous support, wherein the polymer material comprises: The amount of the polymeric material having at least two types of polymeric materials having different moisture permeability coefficients and having a higher moisture permeability coefficient among the polymeric materials is such that one end (R4) to the other end (L4) of the gas diffusion layer. The gas diffusion layer for polymer electrolyte fuel cells, which is characterized by increasing in number. 4. A polymer electrolyte membrane, a catalyst layer containing conductive carbon particles and a metal catalyst arranged on both sides of the polymer electrolyte membrane, and at least one of the catalyst layers. An electrolyte membrane-electrode assembly for a polymer electrolyte fuel cell, comprising the gas diffusion layer according to claim 1. 5. A laminate of single cells, comprising an electrolyte membrane-electrode assembly according to claim 4, and a conductive separator plate having gas passages arranged on both sides of the electrolyte membrane-electrode assembly. A polymer electrolyte fuel cell comprising:
An oxidant gas is caused to flow through a gas flow path of the conductive separator plate arranged with respect to the gas diffusion layer according to any one of claims 1 to 3, and the one end (R2, R3, R
4) is located on the inlet side of the oxidant gas, and the other end (L
2, L3, L4) are located on the outlet side of the oxidant gas.