JP2003208904A - Carbonaceous material for fuel cell having electroconductivity and water repellency in combination - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a carbonaceous material having required characteristics of water repellency and electroconductivity in combination as a material for a fuel cell material. <P>SOLUTION: This is the carbonaceous material for the fuel cell comprised that carbon black whose adsorbed water amount in relative pressure (P/Po) 0.4 per unit specific surface area is 3.0×10<SP>-3</SP>to 9.0×10<SP>-3</SP>mg/m<SP>2</SP>is surface treated by a water-repellent substance. The water-repellent substance is one kind or more among fluororesin, silicone resin, silane coupling agent, and wax, and the surface treatment is carried out by a wet-type method. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a carbonaceous material having both conductivity and water repellency, and a gas diffusion layer, a catalyst layer, and a separator of a solid polymer type or phosphoric acid type fuel cell electrode using the same. And its manufacture.

[0002]

2. Description of the Related Art Conventionally, a fuel cell has been known as an apparatus for directly converting chemical energy of fuel into electric energy. This fuel cell generally includes a pair of electrodes using a porous material, that is, a fuel electrode (anode electrode) and an oxidant electrode (cathode electrode), and an electrolyte layer for holding an electrolyte interposed between the electrodes. By bringing a fuel gas as a reaction gas into contact with the back surface of the device, the electrochemical reaction generated at this time is utilized to take out electric energy from between the electrodes.

The fuel electrode has a structure in which a catalyst for extracting electrons from hydrogen, a gas diffusion layer for hydrogen as a fuel, and a separator as a current collector are laminated. The oxidant electrode has a structure in which a reaction catalyst of protons and oxygen, a gas diffusion layer of air, and a separator are laminated. A solid polymer type fuel cell using a sulfonic acid-based proton conductive solid polymer membrane (electrolyte membrane) as an electrolyte is expected to be put to practical use at low temperatures.

Here, 1 / 2O ₂ + 2H at the cathode electrode
^In order to quickly remove the water generated by the reaction of ⁺ + 2e ⁻ → H ₂ O, it is necessary to impart not only conductivity but also water repellency to the electrode member. For example, as a method of manufacturing the gas diffusion layer, a conductive material such as carbon black or graphite and a fluororesin serving as a binder and a water repellent are mixed and applied to a porous material made of carbon paper or a carbon fiber body. A method of forming a layer having both conductivity and water repellency is known (Japanese Patent Laid-Open No. 10-261,42).
No. 1, JP 2001-43,865, etc.). The catalyst layer is formed by supporting a catalyst substance such as platinum or ruthenium on a carbonaceous material such as carbon particles and mixing it with a binder resin and coating it on the electrolyte membrane, or after forming it on the gas diffusion layer and then forming the electrolyte membrane. And hot pressing, etc. (Japanese Patent Application Laid-Open Nos. 7-211,324 and 8-13
No. 8,683).

A method of forming a layer of catalyst-supporting carbon black on a layer of conductive particles and a water-repellent material such as tetrafluoroethylene, and forming a bonded body with the solid polymer electrolyte Is also known (Japanese Patent Laid-Open No. 7-296,818, etc.). The separator is made by press molding of a graphite sheet, resin impregnated material in which a carbon sintered body is impregnated with resin, glassy carbon, thermosetting resin such as epoxy resin, and carbonaceous material such as carbon black or graphite is blended. And the like are known (Japanese Patent Laid-Open No. 58-53,167 and Japanese Patent Laid-Open No. 60-37,670).
JP, JP-A-60-246,568, JP, 20
No. 00-239,488).

[0006]

However, when the gas diffusion layer is formed by the known method as described above, if the amount of the water repellent is large, the electrical resistance value increases and sufficient conductivity cannot be maintained. On the contrary, when the amount of the water repellent is small, sufficient water repellency cannot be obtained, which hinders gas permeation, resulting in deterioration of battery performance.

The same applies to the catalyst layer and the separator. In the catalyst layer, a large amount of water covers the periphery of the catalyst, so that the catalytic function is deteriorated. Further, the separator usually forms a groove for passing gas, but when the water repellency of the separator groove is poor, water adheres and the gas flow path is closed, and moisture formed at the boundary between the air electrode and the electrolyte is formed. If the water was not removed, the reaction of the air electrode did not proceed at the portion where this water interfered, resulting in a decrease in battery performance.

[0008] For use as a conductive material for fuel cells, attempts have been made so far to subject a conductive material such as a carbonaceous material to a water repellent treatment. For example, JP 2000
-239,704, conductive materials such as carbon black, carbon paper, graphite, nickel powder, and titanium sponge are mixed with various silane coupling agents in the presence of ethanol, or cyclic silicone oil is used. And then mixed with various silane coupling agents for water repellent treatment. Then, from the obtained weight change of the object to be treated and the infrared absorption spectrum by the diffuse reflection method, the water repellent film is a chemical adsorption monomolecular film chemically bonded to the surface of the fine particles.

Further, in Japanese Unexamined Patent Publication (Kokai) No. 6-256,008, carbon particles are reacted with fluorine at 350 to 600 ° C. for 1 minute to 6 hours to obtain fluorinated carbon particles, which are used in a battery such as a fuel cell. It is described to be used as a material. However, none of the water-repellent carbon materials obtained by these conventional methods impairs the conductivity due to the progress of the water-repellent treatment and cannot satisfy the required performance.

It is an object of the present invention to provide a conductive material for a fuel cell, in which the water repellent amount is as small as possible and the water repellent performance and the conductive performance are compatible for a long period of time.

[0011]

Means for Solving the Problems The present inventors have made extensive studies in view of the above problems. As a result, the present inventors have found that the material obtained by subjecting a specific carbonaceous material to water repellency treatment has excellent performance as a material for fuel cells, which has both required properties of water repellency and conductivity. did. That is, the present invention is

(1) Relative pressure per unit specific surface area (P /
Po), the amount of adsorbed water at 0.4 is 3.0 × 10 ⁻³
A carbonaceous material for fuel cells, which is obtained by surface-treating carbon black having a content of ˜9.0 × 10 ⁻³ mg / m ² with a water-repellent substance, and (2) surface treatment with a water-repellent substance is carried out by a wet method. A carbonaceous material for a fuel cell according to the above (1),
(3) The carbonaceous material for a fuel cell according to (1) or (2) above, wherein the water-repellent substance is one or more of fluororesin, silicon resin, silane coupling agent, and wax.

(4) A dispersion containing the carbonaceous material for a fuel cell according to any one of (1) to (3) above, (5) a fuel according to any one of (1) to (3) above. A material for a fuel cell electrode, which comprises a carbonaceous material for a cell and a catalyst substance supported thereon,
(6) A fuel cell electrode containing the fuel cell electrode material according to (5) above, (7) the fuel cell carbonaceous material according to any one of (1) to (3) above as a binder resin. A gas diffusion layer for a fuel cell, which is prepared by impregnating a porous material

(8) A fuel cell separator formed by blending the carbonaceous material for fuel cell according to any one of (1) to (3) above with a thermosetting resin, and molding (9) above ( 4) A method for producing a gas diffusion layer for a fuel cell, which comprises blending the dispersion according to 4) with a binder resin, and impregnating the porous material with the binder resin. (10) The dispersion according to (4) above is a thermosetting resin. (11) Adsorbed water content at relative pressure (P / Po) 0.4 per unit specific surface area of 3.0 × 10
^{-3 to} 9.0 × 10 ^-3 mg / m ² of carbon black, which is a carbonaceous material obtained by surface-treating a carbon black with a water-repellent substance.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. [Carbon Black] In the present invention, the following carbon materials are used. That is, the amount of adsorbed water at a relative pressure (P / Po) of 0.4 per unit specific surface area is 3.
It is a carbon black of 0 × 10 ^{−3 to} 9.0 × 10 ⁻³ mg / m ² .

The carbon black is not particularly limited, and typical examples include furnace black, Ketjen black, and acetylene black. A single type or a plurality of types of carbon black may be mixed and used regardless of the particle size, structure, surface properties and the like. Regardless of the shape of carbon black, beads, pellets,
Examples include powder and flakes, but powder is preferable,
More preferably, the carbon black having a 5 μm filter residue measured in the state of carbon black-water slurry is 200 ppm or less.

Here, the relative pressure (P /
The value of Po) 0.4 is used because the adsorption isotherm in which the adsorption capacity is plotted for each relative pressure is analyzed in detail,
/ Po) It was found that the adsorption capacity of 0 to 0.4 reflects the microstructure of the carbon black surface such as the crystal structure of the carbon black surface and the type and amount of functional groups, and the carbon black itself. Based on the fact that the properties such as the improvement of the water repellency and heat resistance of the carbon black and the sufficient water repellency even at a low level of water repellency treatment are extremely related to the micro state of carbon black. It is a thing.

Further, the degree of development of the crystal structure (crystallite) related to the increase or decrease of the adsorbed water content changes depending on the specific surface area or the particle size. It is preferable to judge by the value divided by the specific surface area. More preferably, in addition to these characteristics, the amount of H _{2 in} the gas desorbed at 1500 ° C. is 0.5 mg /
It is carbon black of g or less.

As the powdery carbon black, for example, one which has not been granulated in a furnace black manufacturing plant is suitable, but granulated granular products pulverized by a jet mill or the like can also be used. Further, the 5 μm filter residual coarse particles can be used as they are if they are produced from the furnace black manufacturing plant within the above range, but regarding the carbon black deviated to the upper limit side,
It may be used after removing coarse particles with an ultrasonic filter (for example, the method described in JP-A-61-89262) or "Air Finex" (manufactured by Fuji Paudal).

Relative pressure per unit specific surface area (P / Po)
The amount of adsorbed water at 0.4 is 3.0 × 10 ^{−3 to} 9.0.
The carbon black of × 10 ⁻³ mg / m ² is, for example, in a vacuum, for example, in a N ₂ gas flow, in a vacuum, in a carbon black produced from a manufacturing plant by a furnace method, a contact method, an acetylene method, a thermal method, or the like in an oxygen-free atmosphere. Alternatively, it can be obtained by heat-treating in carbon powder (which is generally called coke powder, which is referred to as claw powder). The oxygen concentration in the atmosphere is preferably 1% by volume or less, and if it exceeds this, the yield of carbon black decreases, which is not preferable.

When the heat treatment is carried out on a large scale, an Acheson type electric furnace is used, and when the heat treatment is carried out on a small scale, a graphite pipe is filled with carbon black and embedded in carbon powder.
A method in which an alternating current is passed through both ends of the pipe is advantageous. In such a method, as the heat treatment temperature is increased, the crystallites inside the carbon black are rearranged, and the crystallite Lc (size of the crystallite in the c-axis direction) is increased, but when the heat treatment temperature is 2300 ° C. or higher. The structure in which the particles are fused and the agglomerates formed by agglomeration of the structure are strengthened, or (P / P per unit specific surface area)
o) The amount of adsorbed water at 0.4 is 3.0 × 10 ⁻³ m
It becomes less than g / m ^2, and the dispersibility in a solvent such as water or alcohol becomes extremely poor.

On the other hand, when the temperature is 1700 ° C. or lower, not only crystallites hardly develop, but also the amount of adsorbed water at (P / Po) 0.4 per unit specific surface area, which affects heat resistance, is 9.0 ×. In addition to exceeding 10 ⁻³ mg / m ² , H ₂ components in ash and volatile components were not removed, and as a result,
It cannot be an excellent water-repellent carbon black. The heat treatment time is not particularly limited, but is preferably set in the range of 0.5 to 10 hours.

The particle size of carbon black is not particularly limited as described above, but as will be described later, a catalyst is supported on the water-repellent carbonaceous material of the present invention as an electrode material. When used, it is preferable to use carbon black having a small particle size and a large specific surface area. More specifically, the average primary particle diameter (arithmetic average diameter by an electron microscope) is 100 nm or less, preferably 60 nm.
Hereafter, it is more preferably 20 nm or less. Specific surface area (by low temperature nitrogen adsorption method (JIS K621
7)) is preferably 20 m ² / g or more, particularly preferably 30 m ² / g or more, more preferably 200 m ² / g.
That is all. By using carbon black having such a small particle diameter and a high specific surface area, the amount of catalyst that can be supported on the carbon black per unit weight increases, and high catalyst efficiency can be exhibited.

[Water repellent treatment] The above carbon black is subjected to a water repellent treatment with a water repellent substance. The method of water repellent treatment is not limited, and either a dry method or a wet method may be used. In the case of the dry method, for example, carbon black and a water-repellent substance are charged into a convection type powder mixer, a rotary type powder mixer, specifically, a ball mill, a jet mill, a hybridizer, a Henschel mixer or the like and mixed. There is a method.

In the case of the wet method, carbon black and a water-repellent substance are mixed in a solvent or an aqueous medium, carbon black is dispersed in a solution of the water-repellent substance and the solution is distilled off. , A method of selecting and reacting a water-repellent substance having a functional group capable of reacting with a carboxy group and a hydroxyl group of carbon black, and the like, and carbon black is previously prepared as an aqueous dispersion to obtain a solution of the water-repellent substance in an organic solvent. There is a method of utilizing so-called flushing in which carbon black is transferred to the organic solvent phase by dropping. According to this method, carbon black, which is difficult to be finely dispersed, is finely dispersed in water in advance, which is advantageous because the treatment with the water-repellent substance can be performed uniformly.

[Water-repellent substance] As the water-repellent substance, a highly water-repellent material such as PTFE (polytetrafluoroethylene), FEP (fluorinated ethylene polypropylene copolymer), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) , ETFE
(Ethylene / tetrafluoroethylene copolymer), PC
TFE (polychlorotrifluoroethylene), PVDF
(Polyvinylidene fluoride), E-CTFE (trifluorochloroethylene-ethylene copolymer) and other fluororesins,
Silicon resin, a silane coupling agent, and a wax may be mentioned, and PTFE having a particularly high water repellency is particularly preferable.

Further, in the above-mentioned method utilizing flushing, an organic solvent which can be easily removed after the treatment is used, and a water-repellent substance which can be dissolved or uniformly dispersed therein may be selected.
Examples of the organic solvent include those which are hardly soluble in water, such as toluene, xylene, tetrahydrofuran, and n-hexanone. Further, examples of the water-repellent substance which can be dissolved or uniformly dispersed in these organic solvents include fluororesins and silicone resins.

The amount ratio of carbon black and water repellent substance may be appropriately selected depending on the desired degree of water repellency, but generally 0.5 part by weight of water repellent substance to 100 parts by weight of furnace black. To 15 parts by weight, particularly preferably 1 part by weight to 10 parts by weight of the water-repellent substance with respect to 100 parts by weight of furnace black. Within this range, the balance between water repellency and conductivity is excellent. If the water-repellent substance is less than 0.5 parts by weight with respect to 100 parts by weight of the furnace black, the water repellency tends to be insufficient. On the other hand, if it exceeds 15 parts by weight, the conductivity may be insufficient.

As described above, by treating a specific furnace black with a water repellent substance to impart water repellency, it is possible to obtain a conductive carbon material having a good balance of conductivity and water repellency. The carbonaceous material of the present invention may be mixed with a water repellent agent for having a role of a binder, water or an organic solvent at an arbitrary ratio, and then impregnated into a porous material such as carbon paper or carbon fiber body. Thus, the gas diffusion layer of the fuel cell electrode can be obtained.

The organic solvent and water repellent that can be used here are not particularly limited, and those conventionally used when forming the gas diffusion layer for a fuel cell may be appropriately used. Specifically, as the water repellent for giving a role as a binder, for example, a fluororesin is preferable from the viewpoint of its excellent water repellency and binding property, and more specifically, FEP,
In addition to PTFE, ETFE, and perfluorosulfonic acid resins, solvent-soluble fluororesins (“Lumiflon LF100” manufactured by Asahi Glass Co., Ltd.) to which a carboxyl group or a hydroxyl group has been added or graft treatment has been performed to impart solubility to organic solvents. "Lumiflon LF200", "Lumiflon LF302", "Lumiflon LF400", "Lumiflon LF554",
"Lumiflon LF600", "Cefural Coat A101E" manufactured by Central Glass Co., Ltd., "Cefural Coat A2"
02B ”,“ Sephralcoat A402B ”,“ Sephralcoat A610X ”,“ Sephralcoat A670X ”,
"Cefural coat A680XS", "Cefural coat W
S250 "(water system)," Sephral coat FG700X "
(Graft-treated product) and the like. Solvent-soluble fluororesins and the like. Further, the proportions of the carbonaceous material, the water repellent, the water or the organic solvent of the present invention are not particularly limited, and may be adjusted to physical properties suitable for the impregnation work.

At this time, if necessary, a surfactant,
You may use resin etc. as a dispersing agent. Since carbon paper and carbon fiber bodies have many voids and have high conductivity in the plane direction, but conductivity in the thickness direction is lower than that in the plane direction, it is necessary to fill the voids with the carbonaceous material of the present invention. Thus, the purpose of stabilizing the conductivity can also be achieved.

The carbon material for a fuel cell of the present invention is preferably an organic solvent or an aqueous medium (which can be removed by drying in advance, for example, alcohols such as ethanol, propyl alcohol, etc., hydrocarbons such as benzene, toluene, etc. , Acetate, ether, lactone,
It is also possible to employ a method in which a dispersion liquid is dispersed in an amine, an amide, an alkyl halide or the like), and this is mixed with a binder resin to impregnate the porous material. By doing so, fine dispersion of the carbonaceous material in the binder resin is relatively easy.

The carbonaceous material for a fuel cell having both conductivity and water repellency of the present invention can exhibit a water repellent effect even when used alone, so that it is not necessary to add a water repellent agent separately. A carbonaceous material and a binder resin having no water repellent effect are mixed with water or an organic solvent at an arbitrary ratio and impregnated into a porous material such as carbon paper or a carbon fiber body to form a gas for a fuel cell electrode. A diffusion layer can be obtained.

In this case, a small amount of known binder resin such as acrylic, urethane, epoxy, polyester, etc. having a strong fixing force may be used as the binder resin, in addition to the binder resin which is also used as the water repellent. From
It is also possible to firmly adhere to the porous material, and it is possible to increase the filling rate of the carbonaceous material as the conductive material. Also in this case, if necessary, a surfactant, a resin or the like may be used as a dispersant, and carbon paper, by filling the carbonaceous material of the present invention into the voids of a porous material such as a carbon fiber body, The purpose of stabilizing the conductivity can also be achieved.

The carbonaceous material of the present invention having both conductivity and water repellency can be used as a water repellent catalyst by supporting a catalyst substance such as platinum or ruthenium by a known method. The carbonaceous material for fuel cells of the present invention supporting a catalyst substance such as platinum is mixed with a binder resin, water or an organic solvent at an arbitrary ratio, and impregnated and applied to a porous material such as carbon paper or carbon fiber body. By doing so, a catalyst layer for a fuel cell can be obtained. If necessary, a surfactant, a resin or the like may be used as a dispersant. The carbonaceous material for a fuel cell of the present invention has a water-repellent effect even when used alone. Therefore, in addition to a binder resin having a water-repellent effect,
A known binder resin such as an acrylic resin can be used.

The carbonaceous material for a fuel cell according to the present invention is blended with a thermosetting resin as described in, for example, Japanese Patent Application Laid-Open No. 2000-239,488 to form a fuel having water repellency. It is possible to obtain a battery separator.

[0037]

EXAMPLES Example 1 The following water repellent treatment was performed using a commercially available carbon black A having the physical properties shown in Table 1.

(Water repellent treatment) As a water repellent substance, a solvent-soluble fluororesin ("Lumiflon LF200", Asahi Glass Co., Ltd.)
Made in toluene (hereinafter referred to as "fluorine resin solution")
The following operation was carried out with a blending ratio of 5 parts by weight in terms of solid content in the solvent-soluble fluororesin to 95 parts by weight of carbon black. Carbon black A was added to ion-exchanged water so as to be 2.5% by weight, and 90 with a homomixer.
It was dispersed at 00 rpm for 30 minutes. While stirring this solution, a fluororesin solution was added dropwise for water repellent treatment. After the fluororesin solution was added dropwise, the mixture was stirred for several minutes and then filtered with a mesh of 200 mesh. After mesh filtration, dry overnight at room temperature, then 8
It was dried in a vacuum dryer at 0 ° C. to obtain a water repellent carbonaceous material.

(Physical properties of carbon blacks A to C)

[0040]

[Table 1]

In Table 1, 5 μm or more of coarse particles (5 μm filter residue) is 400 m of pure water in which 5% of a nonionic dispersant (for example, “NS220” manufactured by Nissan Co., Ltd.) is dissolved.
20 g of carbon black in 1 l of homogenizer 400
Disperse for 30 minutes at 0 rpm. This dispersion was first filtered with a nylon filter having a pore size of 5 μm in the same manner, and the residue on the filter was weighed and calculated.

The amount of H _{2 at} 1500 ° C. is such that 0.1 to 0.5 g of carbon black dried at 105 ° C. for 1 hour is put into a heat-resistant porcelain sample tube and the pressure is reduced to 10 ⁻⁵ Torr or less, then 1500 ° C. After heating for 30 minutes in an electric furnace whose temperature was raised to 1, the desorbed gas was analyzed by chromatography to determine the amount of H ₂ .

The amount of adsorbed water at the relative pressure is "Omni soap 10" manufactured by Coulter Quality Counter.
0CX "and the conditions described in" Coulter Omnithorpe Operators Guide (published February 1991) ". However, the pretreatment of carbon black was performed at 300 ° C. for 3 hours in a vacuum state of 10 ⁻⁵ Torr or less. The average particle diameter is an arithmetic average diameter by an electron microscope, the specific surface area is a value by a low temperature nitrogen adsorption method (according to JISK6217), and the DBP oil absorption is ASTM D-3493.
It is a value according to -88.

The water-repellent furnace black thus obtained was subjected to the following evaluation tests. (Water repellency test) 0.1 g of the sample and 10 g of ion-exchanged water are put in a sample bottle, and the state after the lid is shaken well is evaluated visually by the following criteria.

<Water Repellent Criteria> First Step: Floating State of Sample ... Most floating samples are judged to have high water repellency. Second stage: Liquid turbidity: No turbidity is judged to have high water repellency. Water repellency is evaluated by ◯ Δx at these two points. The results are shown in Table-2.

(Conductivity test) The powder resistance of the sample was measured using "Loresta PA" manufactured by Mitsubishi Chemical Corporation. The temperature was room temperature and the load was 16 kg / cm ² . The results are shown in Table-2. It can be seen that even if the water repellent treatment is performed with the fluororesin, the powder resistance remains on the same order as before the treatment.

Comparative Example 1 An evaluation test was conducted on carbon black A not subjected to the water repellent treatment in the same manner as in Example 1. The results are shown in Table-2.

Comparative Example 2 The same water repellent treatment as in Example 1 was carried out except that carbon black B (physical properties shown in Table 1) was used in place of carbon black A. The evaluation test of the obtained water-repellent carbon black was conducted in the same manner as in Example 1. The results are shown in Table-2.

(Comparative Example 3) The same water repellent treatment as in Example 1 was carried out except that carbon black C (physical properties shown in Table 1) was used in place of carbon black A. The evaluation test of the obtained water-repellent carbon black was conducted in the same manner as in Example 1. The results are shown in Table-2.

[0050]

[Table 2]

Considering the results in Table 2, the water-repellent treated carbon black obtained by the water-repellent treatment using carbon black having a water adsorption amount within a specific range shows a powder resistance after the water-repellent treatment. Is in the same order as before treatment, and it can be seen that sufficient water repellency is obtained while maintaining high conductivity.

【The invention's effect】

In the water-repellent carbonaceous material of the present invention, the surface of the furnace black, which is in the form of extremely fine particles, is subjected to the water-repellent treatment, so that the surface area contributed by the water-repellent substance is large and a small amount can be obtained. It is considered to have a water repellent effect. At the same time, it is considered that it is possible to maintain high conductivity because the crystallites are developed to the extent shown in the range of the specific adsorbed water content. When the carbonaceous material having both conductivity and water repellency of the present invention is used in the gas diffusion layer for a fuel cell, the amount of the water repellent agent used as the binder and water repellent agent should be significantly reduced. Is possible.
For this reason, the electrical resistance of the gas diffusion layer can be significantly reduced, and battery performance can be expected to improve.

When a carbonaceous material having both conductivity and water repellency according to the present invention is used as a catalyst component by supporting a catalyst substance such as platinum, the water repellent used as a binder and a water repellent is the same. It is possible to greatly reduce the amount used, it is possible to greatly reduce the electrical resistance value, and it can be expected that the battery performance will be improved.

Since the carbonaceous material of the present invention having both conductivity and water repellency has water repellency even when used alone, a gas diffusion layer can be obtained by fixing it with a binder resin other than a water repellent. You can

When used for a separator application,
It is possible to achieve both conductivity and water repellency by mixing with a separator material resin such as a thermosetting resin.

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Claims (11)

[Claims] 1. Relative pressure per specific surface area (P / Po)
The amount of adsorbed water at 0.4 is 3.0 × 10 ^{−3 to} 9.0.
A carbonaceous material for a fuel cell obtained by surface-treating carbon black having a density of × 10 ^-3 mg / m ² with a water-repellent substance. 2. The carbonaceous material for a fuel cell according to claim 1, wherein the surface treatment with the water-repellent substance is performed by a wet method. 3. The carbonaceous material for a fuel cell according to claim 1, wherein the water-repellent substance is one or more of a fluororesin, a silicon resin, a silane coupling agent, and a wax. 4. A dispersion liquid containing the carbonaceous material for a fuel cell according to claim 1. 5. A material for a fuel cell electrode, which comprises a carbonaceous material for a fuel cell according to claim 1 and a catalyst substance supported on the carbonaceous material. 6. A fuel cell electrode containing the fuel cell electrode material according to claim 5. 7. A gas diffusion layer for a fuel cell, which is obtained by blending the carbonaceous material for a fuel cell according to claim 1 with a binder resin and impregnating the porous material. 8. A fuel cell separator formed by blending the carbonaceous material for a fuel cell according to claim 1 with a thermosetting resin and molding. 9. A method for producing a gas diffusion layer for a fuel cell, which comprises blending the dispersion according to claim 4 with a binder resin and impregnating the porous material. 10. A separator for a fuel cell, which is obtained by blending the dispersion according to claim 4 with a thermosetting resin and molding the mixture. 11. Relative pressure per unit specific surface area (P / P
o) The amount of adsorbed water at 0.4 is 3.0 × 10 ⁻³
A carbonaceous material obtained by surface-treating carbon black of 9.0 × 10 ⁻³ mg / m ² with a water-repellent substance.