JP2003288906A - Carbon fiber cloth for electrode, gas diffusion body, membrane-electrode joint body, and fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin carbon fiber cloth 2 for an electrode having high controllability of produced water in power generation reaction. <P>SOLUTION: This carbon fiber cloth 2 used in an electrode material of fuel cell has a pressure difference more than 0.2 mmAq and less than 1.6 mmAq when air of 14 cm<SP>3</SP>/cm<SP>2</SP>/sec is permeated in the thickness direction, and a thickness of less than 150 μm. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a carbon fiber woven fabric suitable as a material for electrodes, particularly as a material for a gas diffuser of a polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art A gas diffuser for a fuel cell electrode is required to have a current collecting function and diffusion / permeability of substances involved in an electrode reaction, conductivity, and strength to withstand handling.

As a material for such a gas diffuser of a fuel cell electrode, for example, JP-A-6-20710, JP-A-7-326362, and JP-A-7-220735.
There is known one using a porous carbon plate formed by binding short carbon fibers with carbon as described in Japanese Patent Publication No. 2003-242242. However, since it is difficult to obtain such a material for the gas diffusion material in a continuous roll shape, there is a problem in productivity and cost. In addition, there is a problem that the binding carbon is easily broken by the pressure applied when manufacturing the electrode or when assembled in a battery.

A carbon fiber woven fabric is used as a material for a gas diffuser which can be manufactured in a continuous roll form. Specifically, Stackp described in US Pat. No. 4,293,396.
Product "PANEX PWB-3" from oleFibers Company and Japanese Patent Laid-Open No. 1
The product “AVCARB” manufactured by Textron Specialty Materials Co., Ltd., which is described in JP-A-0-261421, may be mentioned.

By the way, water is produced at the cathode by the power generation reaction of the polymer electrolyte fuel cell. Unless the generated water is efficiently discharged to the outside of the system, the oxidizing gas required for the reaction becomes difficult to be supplied to the catalyst layer due to the water clogging of the gas diffuser, and the output of the battery decreases.

On the other hand, the proton conductivity of the solid polymer electrolyte membrane that transfers protons from the anode side to the cathode side is reduced unless it is in a wet state. Therefore, even if the drainage property of the gas diffuser of the cathode is too high, the proton conductivity decreases due to the drying of the solid polymer electrolyte membrane, and the output of the battery decreases.

The drainage step in the gas diffuser of the cathode is considered to be divided into two main movements: movement of water in the gas diffuser and evaporation of water on the surface of the gas diffuser.

Regarding the movement of water in the gas diffuser, the smaller the thickness of the gas diffuser, the smaller the distance of water transfer in the thickness direction required for discharging the water produced by the reaction to the outside of the system, and the efficiency is improved. Well water is carried to the surface of the gas diffuser. Further, if the thickness of the gas diffuser is reduced, the fuel cell stack can be made compact and the power density of the cell is improved. Also, regarding the evaporation of water on the surface of the gas diffuser,
It is considered that the operating temperature of the fuel cell, the humidifying conditions of the oxidizing gas, and the flow velocity of the oxidizing gas on the surface of the gas diffuser have a large influence.

The operating temperature of the polymer electrolyte fuel cell is 70 to
80 ° C. is common, and it is difficult to change the operating temperature to control the evaporation of the produced water. Although it is generally performed to control the evaporation of the produced water depending on the humidifying condition of the oxidizing gas, the control of the produced water by the power generation reaction is not sufficient by itself.

Further, since the amount of the oxidizing gas required for the power generation reaction is determined by the stoichiometric relationship, it is difficult to control the evaporation of the generated water by the supply flow rate of the oxidizing gas. However, by changing the gas permeability of the gas diffuser, it is possible to control the flow rate of the oxidizing gas on the surface of the gas diffuser and to control the evaporation of water generated by the power generation reaction.

[0011]

However, from this point of view, the product "PANEX PWB-" of Stackpole Fibers Company described in US Pat. No. 4,293,396 is disclosed.
3 ”had a large thickness as a material for the gas diffuser and had low gas permeability. Therefore, the water transfer distance in the thickness direction required to discharge the water generated by the power generation reaction to the outside of the system. And the flow velocity of the oxidizing gas on the surface of the gas diffuser is small, so that there is a problem that water clogging occurs in the gas diffuser and the fuel cell cannot exhibit sufficient performance.

It is an object of the present invention to provide a carbon fiber woven fabric for an electrode which overcomes the drawbacks of the prior art, has a small thickness, and is excellent in the controllability of water produced by a power generation reaction.

[0013]

In order to achieve the above-mentioned object, the carbon fiber woven fabric for electrodes of the present invention is 14 cm ³ / cm ² / s.
When the ec air is passed through in the thickness direction, the differential pressure is 0.2
It is characterized by exceeding mmAq and less than 1.6 mmAq, and having a thickness of less than 150 μm.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a partial sectional view showing an example of a membrane-electrode assembly 4 proposed in the present invention. In FIG. 1, a gas diffuser 1 according to the present invention has a carbon fiber woven fabric 2 in which a plurality of carbon fibers are aggregated as a base material, and a carbon layer 3 containing carbon black and a fluororesin on at least one surface thereof. Have. The membrane-electrode assembly 4 according to the present invention is
A catalyst layer 6 is provided on both surfaces of the solid polymer electrolyte membrane 5, and a gas diffuser 1 is provided in contact with the surfaces of both catalyst layers 6, 6.

The above is the overall structure, but the carbon fiber woven fabric 2 according to the present invention has a thickness direction of 14 cm ³ / cm ² / s.
The gas permeation resistance defined by the differential pressure when permeating air of ec is more than 0.2 mmAq and less than 1.6 mmAq, more preferably 0.4 mmAq or more and 1.4 mmAq or less, and 0.6 mmAq or more 1. It is more preferably 1 mmAq or less. Gas permeation resistance of carbon fiber fabric 2 is 0.2 mm
When it is Aq or less, the gas flow velocity on the surface of the gas diffuser 1 increases, and the evaporation rate of water generated by the power generation reaction of the fuel cell increases. Therefore, the proton conductivity is lowered by the drying of the solid polymer electrolyte membrane 5, and the output of the battery is lowered. When the gas permeation resistance of the carbon fiber woven fabric 2 is 1.6 mmAq or more, the gas flow velocity on the surface of the gas diffuser 1 becomes small, and the evaporation rate of water generated by the power generation reaction becomes small. Therefore, due to water clogging inside the gas diffuser 1, it becomes difficult for the oxidizing gas to be supplied to the catalyst layer 6, and the output of the battery decreases.

The carbon fiber fabric 2 has a thickness of 150 μm.
Less than 145 μm, more preferably 140 μm
m or less is more preferable. The thickness of the carbon fiber woven fabric 2 is 150
When it is at least μm, the transfer distance of water in the thickness direction required for discharging the water generated by the power generation reaction to the outside of the system becomes large, and the transfer efficiency of water to the surface of the gas diffuser 1 decreases. Therefore, the output of the battery is reduced due to water clogging inside the gas diffuser 1.

The thickness of the carbon fiber woven fabric 2 is preferably 50 μm or more, more preferably 100 μm or more, still more preferably 120 μm or more. When the thickness of the carbon fiber woven fabric 2 is less than 50 μm, the number of single yarns constituting the woven fabric is reduced, the tensile strength is reduced, and the handling property in a continuous roll state is reduced.

The carbon fiber woven fabric 2 has a surface pressure of 1.0M.
Pa is the thickness when pressurized.

The basis weight of the carbon fiber woven fabric 2 is preferably less than 72 g / m ^2, greater 99 g / m ^2, 80 g /
m is more preferably ² or more 97 g / m ² or less, 85 g / m ²
More preferably, it is 95 g / m ² or less. Carbon fiber fabric 2
When the fabric weight is 72 g / m ² or less, the gap formed by the warp and the weft of the woven fabric becomes large, and the gas permeation resistance becomes too small. When the basis weight is 99 g / m ² or more, the gap between the fabrics becomes small and the gas permeation resistance becomes too large.

The density of the carbon fiber woven fabric 2 is 0.50 to 0.8.
It is preferably 0 g / cm ³ , and 0.60 to 0.7
5 g / cm ³ is more preferable, and 0.65 to 0.70 g /
cm ³ is more preferable. Carbon fiber fabric 2 has a density of 0.5
If it is less than 0 g / cm ³ , the gas permeation resistance becomes too small, and if it exceeds 0.80 g / cm ³ , the gas permeation resistance becomes too large. The density of the carbon fiber woven fabric 2 is calculated from the basis weight and the thickness when the surface pressure is 1.0 MPa. Further, the carbon fiber woven fabric 2 according to the present invention may be a spun yarn woven fabric or a filament woven fabric, but the spun yarn woven fabric is preferable to the filament woven fabric in which single yarns are easily gathered to easily increase the density.

The number of gaps formed by the warp and weft of the carbon fiber woven fabric 2 as seen in the thickness direction of the woven fabric is 400 to 7
00 / cm ² is preferable, 500 to 680 / cm ² is more preferable, and 550 to 650 / cm ² is further preferable. If the number of gaps in the carbon fiber woven fabric 2 is less than 400 / cm ² , the gas permeation resistance of the woven fabric becomes too large,
If it exceeds 0 / cm ² , the gas permeation resistance becomes too small. The area of each of the gaps formed by the warp threads and the weft threads in the carbon fiber woven fabric 2 is 0.01
~ 0.50 mm ² , preferably 0.02
0.10 mm ² is more preferable, 0.03 to 0.09 m
m ² is more preferred. If the area of each gap of the carbon fiber woven fabric 2 is less than 0.01 mm ² , the gas permeation resistance of the woven fabric becomes too large, and if it exceeds 0.50 mm ² , the gas permeation resistance becomes too small.

The gas diffuser 1 according to the present invention preferably has a carbon layer 3 containing a fluororesin and carbon black on at least one surface of the carbon fiber woven fabric 2. The weight ratio of the fluororesin contained in the carbon layer 3 to carbon black is preferably 0.01 or more and 0.70 or less, more preferably 0.05 or more and 0.60 or less, and 0.1.
It is more preferably 10 or more and 0.40 or less. Carbon layer 3
If the weight ratio of the fluororesin contained in the above to carbon black is less than 0.01, there is a problem that the binder effect of the fluororesin connecting the carbon black becomes small and the carbon layer becomes brittle, and if it exceeds 0.70, There is a problem that the ratio of the fluororesin having a very low conductivity increases and the conductivity of the gas diffuser decreases greatly.

Here, the fluororesin means tetrafluoroethylene resin (PTFE), perfluoroalkoxy resin (PFA), fluorinated ethylene propylene resin (FE).
P), fluorinated ethylene tetrafluoroethylene resin (E
It refers to a water-repellent resin containing a fluororesin in its structure, such as TFE).

Since the gas diffuser 1 according to the present invention uses the carbon fiber woven fabric 2 described above, it has excellent controllability of water produced by the power generation reaction.

By providing the carbon layer 3 on at least one surface of the carbon fiber woven fabric 2, the surface of the gas diffuser 1 becomes smooth, and electrical contact can be easily secured. It also has an effect of preventing the gas diffuser 1 from sticking into the solid polymer electrolyte membrane 5 to cause a short circuit when the membrane-electrode assembly 4 is formed.

The membrane-electrode assembly 4 according to the present invention has the above-mentioned gas diffusion body 1 on at least one side of both gas diffusion bodies 6, 6.
To use. Further, it is preferable that the side on which the gas diffuser 1 is used is the cathode side. The catalyst layer 6 is composed of a layer containing a solid polymer electrolyte and catalyst-supporting carbon. It is preferable to use platinum as the catalyst. When the reformed gas containing carbon monoxide is supplied to the anode side, it is preferable to use platinum and ruthenium as the catalyst on the anode side. The solid polymer electrolyte 5 is preferably made of a perfluorosulfonic acid-based polymer having high proton conductivity, oxidation resistance and heat resistance.

In the membrane-electrode assembly 4 according to the present invention, since at least the cathode side uses the above gas diffuser 1 having excellent water controllability as an electrode material, water clogging due to water generated in the power generation reaction occurs. Since the solid polymer electrolyte membrane 5 is less likely to be deteriorated and the proton conductivity is less likely to decrease due to the drying of the solid polymer electrolyte membrane 5, extremely high battery characteristics are exhibited.

The polymer electrolyte fuel cell according to the present invention is a stack of a plurality of membrane-electrode assemblies 4 shown in FIG. 1 sandwiched by separators with gaskets on both sides. Since the above-mentioned membrane-electrode assembly 4 exhibiting extremely high cell characteristics is used, the fuel cell proposed by the present invention exhibits extremely high performance.

[0030]

An embodiment of the present invention will be described below with reference to the drawings.

(Example 1) A plain weave flame-resistant yarn woven fabric having a basis weight of 140 g / m ² was woven using spun yarn of acrylic flame-resistant fiber ("Lastane" manufactured by Asahi Kasei Corporation, 1/34 Nm). The maximum temperature of this flame resistant yarn fabric is 6 in an inert atmosphere.
The carbon fiber woven fabric was obtained by carbonizing in two steps of 50 ° C and 1950 ° C.

The gas permeation resistance, thickness, basis weight, density, number of crevices in the weave (number of crevices), and the area per crevice in the weave (gap area) were measured. Also,
Create a polymer electrolyte fuel cell using carbon fiber fabric,
Measure the voltage when applying a current of 1.0 A / cm ² ,
The value was used as an index showing the performance of the fuel cell. The measurement results are shown in Table 1 below.

Regarding the gas permeation resistance, the differential pressure when air of 14 cm ³ / cm ² / sec was permeated in the thickness direction of the carbon fiber woven fabric was measured, and the value was taken as the gas permeation resistance. Regarding the thickness, the thickness was measured when the surface pressure was 1.0 MPa. Density is 1.0M in basis weight and surface pressure
It was calculated from the thickness when Pa was applied. The number of crevices in the weave of the carbon fiber woven fabric (the number of crevices) and the area per crevice in the weave (the crevice area) were measured by applying transmitted light from the back surface of the carbon fiber woven fabric and magnifying the surface 20 times with a microscope. Measured from the photograph taken.

The method for measuring the voltage of a polymer electrolyte fuel cell prepared using a carbon fiber woven fabric when a current of 1.0 A / cm ² is passed is shown below.

(Method for Measuring Voltage of Fuel Cell) Carbon fiber woven fabric 2 was coated with a carbon coating liquid using a spacer made of a polyester film having a thickness of 200 μm and a stainless steel plate having a thickness of 1 mm. The applied carbon coating liquid has a solid content of acetylene black (Denka Black manufactured by Denki Kagaku Kogyo KK), PTFE (using Polyflon PTFE Dispersion D-1 manufactured by Daikin Kogyo KK), and a surfactant (TRITON manufactured by Nacalai Tesque KK).
X-114), the ratio of which is 4: 1: 8, purified water is further added, and the solid content is 20.0% of the whole.
It was adjusted to be wt%. The carbon fiber woven fabric provided with the carbon layer 3 is subjected to a desurfactant treatment in an oven at 380 ° C. for 10 minutes, and then hot-pressed for 5 minutes by a batch press at a temperature of 200 ° C. and a surface pressure of 3 MPa to perform gas diffusion. I got body 1.

Platinum-supporting carbon (Tanaka Kikinzoku Co., Ltd., platinum content 50% by weight) 1.00 g, purified water 1.00 g, Nafi
on solution (Nafion 5.0 manufactured by Aldrich)
%) And isopropyl alcohol (manufactured by Nacalai Tesque, Inc.) 18.00 g in order,
A catalyst coating liquid was prepared.

On a PTFE sheet (Naflon tape TOMBO9001 manufactured by Nichias), the above catalyst coating solution was applied in an amount of 5
By spraying on a square of cm ² and drying,
PTFE with catalyst layer having platinum content of 0.5 mg / cm ^2.
Got the sheet. Solid polymer electrolyte membrane 5 cut out into 5 cm × 5 cm (Dafont Nafion 112)
Sandwiched between the above PTFE sheets with a catalyst layer,
The catalyst layer 6 was transferred to the solid polymer electrolyte membrane 5 by batch pressing at 5 MPa for 5 minutes. After pressing, PTF
The E sheet was peeled off to obtain a solid polymer electrolyte membrane with a catalyst layer.

Two pieces each having a square size of 5 cm ² were cut out from the gas diffuser 1. The above-mentioned solid polymer electrolyte membrane with a catalyst layer was sandwiched between the cut gas diffusers 1 and batch-pressed at 130 ° C. and 2 MPa for 5 minutes to obtain membrane-electrode assemblies 4. The gas diffuser 1 was arranged so that the surface having the carbon layer 3 was in contact with the catalyst layer 6 side.

The obtained membrane-electrode assembly 4 was incorporated into a fuel cell evaluation single cell, and hydrogen and air at normal pressure were supplied,
The operating temperature was 70 ° C. Hydrogen and air were humidified by a humidification pot set at 80 ° C and 60 ° C, respectively. The utilization rates of hydrogen and air are 70 each.
% And 40%. The membrane-electrode assembly 4 was used to measure the voltage value of the fuel cell at 1.0 A / cm ² .

Example ² A plain weave flame-resistant yarn woven fabric having a basis weight of 144 g / m ² was woven using a spun yarn of acrylic flame-resistant fiber (“Lastane” manufactured by Asahi Kasei Corporation, 1/34 Nm). The maximum temperature of this flame resistant yarn fabric is 6 in an inert atmosphere.
The carbon fiber woven fabric was obtained by carbonizing in two steps of 50 ° C and 1950 ° C.

In the same manner as in Example 1, gas permeation resistance, thickness, basis weight, density of the obtained carbon fiber woven fabric, number of weave gaps (number of gaps), area per weave gap (gap) Area), a polymer electrolyte fuel cell was prepared using a carbon fiber woven fabric, and the voltage when a current of 1.0 A / cm ² was passed was measured. The measurement results are shown in Table 1 below.

Example 3 A plain weave flame-resistant yarn woven fabric having a basis weight of 150 g / m ² was woven using a spun yarn of acrylic flame-resistant fiber (“Lastane” manufactured by Asahi Kasei Corporation, 1/34 Nm). The maximum temperature of this flame resistant yarn fabric is 6 in an inert atmosphere.
The carbon fiber woven fabric was obtained by carbonizing in two steps of 50 ° C and 1950 ° C.

In the same manner as in Example 1, the obtained carbon fiber woven fabric had gas permeation resistance, thickness, basis weight, density, number of weave gaps (number of gaps), and area per weave gap (gap). Area), a polymer electrolyte fuel cell was prepared using a carbon fiber woven fabric, and the voltage when a current of 1.0 A / cm ² was passed was measured. The measurement results are shown in Table 1.

Example 4 A plain weave flame-resistant yarn woven fabric having a basis weight of 153 g / m ² was woven using spun yarn of acrylic flame-resistant fiber (“Lastane” manufactured by Asahi Kasei Corporation, 1/34 Nm). The maximum temperature of this flame resistant yarn fabric is 6 in an inert atmosphere.
The carbon fiber woven fabric was obtained by carbonizing in two steps of 50 ° C and 1950 ° C.

In the same manner as in Example 1, gas permeation resistance, thickness, basis weight, density of the obtained carbon fiber woven fabric, number of weave gaps (number of gaps), area per weave gap (gap) Area), a polymer electrolyte fuel cell was prepared using a carbon fiber woven fabric, and the voltage when a current of 1.0 A / cm ² was passed was measured. The measurement results are shown in Table 1.

Comparative Example 1 A plain weave flame-resistant yarn woven fabric having a basis weight of 104 g / m ² was woven using a spun yarn of acrylic flame-resistant fiber (“Lastane”, 1/34 Nm, manufactured by Asahi Kasei Corporation). The maximum temperature of this flame resistant yarn fabric is 6 in an inert atmosphere.
The carbon fiber woven fabric was obtained by carbonizing in two steps of 50 ° C and 1950 ° C.

In the same manner as in Example 1, the obtained carbon fiber woven fabric had gas permeation resistance, thickness, basis weight, density, number of weave gaps (number of gaps), and area per weave gap (gap). Area), a polymer electrolyte fuel cell was prepared using a carbon fiber woven fabric, and the voltage when a current of 1.0 A / cm ² was passed was measured. The measurement results are shown in Table 1.

Comparative Example ² A plain weave flame resistant yarn woven fabric having a basis weight of 157 g / m ² was woven using a spun yarn of acrylic flame resistant fiber (“Lastane” manufactured by Asahi Kasei Corporation, 1/34 Nm). The maximum temperature of this flame resistant yarn fabric is 6 in an inert atmosphere.
The carbon fiber woven fabric was obtained by carbonizing in two steps of 50 ° C and 1950 ° C.

In the same manner as in Example 1, gas permeation resistance, thickness, basis weight, density of the obtained carbon fiber woven fabric, number of weave gaps (number of gaps), area per weave gap (gap) Area), a polymer electrolyte fuel cell was prepared using a carbon fiber woven fabric, and the voltage when a current of 1.0 A / cm ² was passed was measured. The measurement results are shown in Table 1.

Comparative Example 3 Carbon Fiber Spun Yarn Fabric Car
Bon “A” Cloth Plain Weave (E
-TEK) was used as a carbon fiber woven fabric for electrodes.

In the same manner as in Example 1, gas permeation resistance, thickness, basis weight, density of the obtained carbon fiber woven fabric, number of weave gaps (number of gaps), area per weave gap (gap) Area), a polymer electrolyte fuel cell was prepared using a carbon fiber woven fabric, and the voltage when a current of 1.0 A / cm ² was passed was measured. The measurement results are shown in Table 1.

(Comparative Example 4) Carbon fiber spun yarn woven fabric Avc
arb 1071HCB Fabric (TEXTRO
N Systems Corporation) was used as a carbon fiber woven fabric for electrodes.

In the same manner as in Example 1, the obtained carbon fiber woven fabric had gas permeation resistance, thickness, basis weight, density, number of weave gaps (number of gaps), and area of each weave gap (gap). Area), a polymer electrolyte fuel cell was prepared using a carbon fiber woven fabric, and the voltage when a current of 1.0 A / cm ² was passed was measured. The measurement results are shown in Table 1.

Comparative Example 5 Carbon fiber filament woven fabric
Torayca cloth (manufactured by Toray Industries, Inc.) “CO6349B” was heated to 1400 ° C. in an inert atmosphere to remove the sizing material and obtain a carbon fiber woven fabric.

In the same manner as in Example 1, the obtained carbon fiber woven fabric had gas permeation resistance, thickness, basis weight, density, number of weave gaps (number of gaps), and area per weave gap (gap). Area), a polymer electrolyte fuel cell was prepared using a carbon fiber woven fabric, and the voltage when a current of 1.0 A / cm ² was passed was measured. The measurement results are shown in Table 1.

[0056]

[Table 1]

As shown in Table 1, since the carbon fiber woven fabrics of Examples 1 to 4 are excellent in the controllability of the water produced by the power generation reaction, the fuel cells using these carbon fiber woven fabrics showed high performance. On the other hand, the carbon fiber woven fabric of Comparative Example 1 has a small gas permeation resistance, the woven fabrics of Comparative Examples 2, 3 and 5 have a large gas permeation resistance, and the woven fabric of Comparative Example 4 has a large thickness. The fuel cell using the fiber fabric did not show sufficient performance.

Therefore, an object of the present invention to provide a carbon fiber woven fabric for an electrode, which is thin and has excellent controllability of water produced by a power generation reaction, is a woven fabric made of carbon fiber, which has a density of 14 cm ³ / cm ^2. / Sec air permeation in the thickness direction, the differential pressure is greater than 0.2 mmAq and 1.6 m
It is achieved by a carbon fiber woven fabric for electrodes, which is less than mAq and has a thickness of less than 150 μm.

[0059]

Since the carbon fiber woven fabric provided by the present invention has a small thickness, the transport distance of water in the thickness direction required for discharging the water generated by the reaction to the outside of the system becomes small, and the water is efficiently transferred. Are transported to the surface of the gas diffuser. Further, since the carbon fiber woven fabric proposed in the present invention has an appropriate gas permeation resistance, it is possible to evaporate excess water, which causes water clogging inside the gas diffuser, of the water generated by the power generation reaction.

Therefore, according to the present invention, a carbon fiber woven fabric for electrodes, a gas diffuser, a membrane-electrode assembly, and a fuel cell which are thin and have excellent controllability of water generated by a power generation reaction can be obtained.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a membrane-electrode assembly proposed by the present invention.

[Explanation of symbols]

1: Gas diffuser 2: Carbon fiber fabric 3: Carbon layer 4: Membrane-electrode assembly 5: Solid polymer electrolyte membrane 6: Catalyst layer

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Claims (8)

[Claims] 1. A carbon fiber woven fabric used as an electrode material for a fuel cell, which has a differential pressure of more than 0.2 mmAq and 1.6 mmAq when 14 cm ³ / cm ² / sec of air permeates in the thickness direction. And a thickness of less than 150 μm, a carbon fiber woven fabric for electrodes. 2. A basis weight of the electrode for carbon fiber woven fabric according to claim 1, characterized in that less than 99 g / m ² exceed 72 g / m ^2. 3. The carbon fiber woven fabric for an electrode according to claim 1, which has a density of 0.50 to 0.80 g / cm ³ . 4. The number of gaps formed by the warp and weft of the woven fabric existing in the carbon fiber woven fabric is 400 to 700 / c.
electrodes for carbon fiber woven fabric according to any one of claims 1 to 3, characterized in that m ² or less. 5. The area of each of the gaps formed by the warp and the weft of the woven fabric existing in the carbon fiber woven fabric is 0.0.
It is 1-0.50 mm < ² >, It is characterized by the above-mentioned.
4. The carbon fiber woven fabric for an electrode according to any one of 4 above. 6. A gas diffuser having a carbon layer containing carbon black and a fluororesin on at least one surface of the carbon fiber woven fabric for an electrode according to claim 1. 7. A membrane-electrode assembly having a catalyst layer containing catalyst-carrying carbon on both surfaces of a solid polymer electrolyte membrane, and further comprising a gas diffuser in contact with the surfaces of both catalyst layers. A membrane-electrode assembly, wherein the gas diffuser according to claim 6 is used in at least one of the diffusers. 8. A fuel cell comprising the membrane-electrode assembly according to claim 7.