Conductive nonwoven fabric and method for manufacturing conductive nonwoven fabric

Abstract

To provide a conductive nonwoven fabric as a conductive sheet capable of being used as a gas diffusion layer in a fuel cell and having excellent winding properties.SOLUTION: The conductive nonwoven fabric is used for a gas diffusion layer of a fuel cell. The conductive nonwoven fabric includes organic fibers and a conducting material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a conductive nonwoven fabric and a method for producing the same.

Background Art

[0002] A fuel cell basically consists of an electrolyte membrane, a fuel electrode (negative electrode) and an oxygen electrode (positive electrode) arranged with the electrolyte membrane therebetween. The fuel electrode is composed of a catalyst layer in contact with the electrolyte membrane and a gas diffusion layer. Similarly, the oxygen electrode is composed of a catalyst layer in contact with the electrolyte membrane and a gas diffusion layer. The gas diffusion layer serves as a site for the battery reaction and as a current collector.

[0003] Patent Document 1 discloses a conductive sheet functioning as such a gas diffusion layer, which is made of carbon fiber as a constituent material.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the manufacturing process of a fuel cell, efforts have been made to improve the productivity of the fuel cell by supplying a conductive sheet to be used as the gas diffusion layer in a rolled state and continuously performing a lamination process of the gas diffusion layer and other layers. This production method is called a roll-to-roll method.

[0006] To supply conductive sheets, which form the gas diffusion layer, using a roll-to-roll method, it is necessary to wind the conductive sheets onto rolls. However, when winding conductive sheets made of carbon fiber onto rolls, the carbon fibers can break if the roll diameter is small, forcing the roll diameter to be increased. This increased roll diameter then reduces the length of conductive sheet that can be wound onto each roll of the same volume, leading to a decrease in fuel cell productivity. Therefore, there was a need for conductive sheets that were less prone to fiber breakage during winding onto rolls and had excellent winding properties.

[0007] The present invention was made to solve the above problems and aims to provide a conductive nonwoven fabric and a method for manufacturing a conductive nonwoven fabric, which can be used as a gas diffusion layer in a fuel cell and has excellent winding properties as a conductive sheet. [Means for solving the problem]

[0008] The conductive nonwoven fabric of the present invention is a conductive nonwoven fabric used in the gas diffusion layer of a fuel cell, and is characterized in that the conductive nonwoven fabric contains organic fibers and a conductive substance.

[0009] The conductive nonwoven fabric of the present invention contains organic fibers as the fibers constituting the nonwoven fabric. Since organic fibers are more flexible than carbon fibers, they are less likely to break when wound onto a roll, and nonwoven fabrics containing organic fibers have excellent winding properties. Furthermore, although organic fibers have poor conductivity, by making the organic fibers conductive by adding a conductive substance in addition to the organic fibers, a conductive nonwoven fabric suitable for use as a gas diffusion layer in fuel cells can be made. In other words, the conductive nonwoven fabric of the present invention can be used as a gas diffusion layer in fuel cells because it is conductive, and its excellent winding properties make it suitable for improving the productivity of fuel cells.

[0010] The conductive nonwoven fabric of the present invention is preferably a papermaking product of a mixture of the above-mentioned organic fibers and the above-mentioned conductive substance. A nonwoven fabric can be obtained by papermaking a mixture of organic fibers and a conductive material, and the nonwoven fabric obtained in this way is a conductive nonwoven fabric. Since the fibers that make up the nonwoven fabric are organic fibers, the conductive nonwoven fabric has excellent flexibility and winding properties.

[0011] The conductive nonwoven fabric of the present invention preferably consists of an organic nonwoven fabric made of the above-mentioned organic fibers and the above-mentioned conductive substance attached to the surface of the above-mentioned organic fibers constituting the organic nonwoven fabric. Conductive nonwoven fabric can also be obtained by preparing an organic nonwoven fabric in advance and attaching a conductive substance to the surface of the organic fibers that make up the organic nonwoven fabric. Since the fibers that make up organic nonwoven fabrics are organic fibers, conductive nonwoven fabrics have excellent flexibility and winding properties.

[0012] Furthermore, in the conductive nonwoven fabric of the present invention, it is preferable that the conductive substance is attached to the surface of the organic fibers constituting the organic nonwoven fabric by impregnation, vapor deposition, plating, sputtering, spray coating, or printing.

[0013] Furthermore, in the conductive nonwoven fabric of the present invention, it is preferable that the organic fiber is at least one selected from the group consisting of polyamide fiber, polyester fiber, acrylic fiber, polyolefin fiber, polyvinyl alcohol fiber, aramid fiber, polyimide fiber, PBO fiber, and PPS fiber. When carbon fibers are used as a material for conductive nonwoven fabrics, high-temperature firing is required during the carbon fiber manufacturing process. However, these organic fibers do not require high-temperature firing during the fiber manufacturing process, making them preferable from the viewpoint of reducing CO2 emissions.

[0014] Furthermore, in the conductive nonwoven fabric of the present invention, it is preferable that the organic fiber is at least one selected from the group consisting of cellulose fiber, aliphatic polyester fiber, aliphatic polyamide fiber, recycled polyethylene terephthalate fiber, and polybutylene succinate fiber. When these fibers are organic fibers, it is preferable to select these fibers because their raw materials are plant-derived or they have biodegradability, so that the environmental load can be reduced by selecting these fibers.

[0015] In the conductive nonwoven fabric of the present invention, the conductive substance is preferably at least one selected from the group consisting of graphite, carbon black, carbonaceous mild fiber, carbon nanotube, gold, silver, copper, platinum, palladium, aluminum, nickel, chromium, and zinc.

[0016] One aspect of the method for manufacturing the conductive nonwoven fabric of the present invention is characterized by including a step of forming a mixture of organic fibers and a conductive substance. Another aspect of the method for manufacturing the conductive nonwoven fabric of the present invention is characterized by including a step of attaching a conductive substance to the surface of the organic fibers constituting the organic nonwoven fabric by impregnation, vapor deposition, plating, sputtering, spray coating, or printing.

Brief Description of the Drawings

[0017] [Figure 1] FIG. 1 is a perspective view schematically showing an example of a conductive nonwoven fabric as a formed article. [Figure 2A] FIG. 2A is a perspective view schematically showing an example of an organic nonwoven fabric. [Figure 2B] FIG. 2B is a perspective view schematically showing an example of a conductive nonwoven fabric in which a conductive substance is attached to the organic fibers constituting the organic nonwoven fabric shown in FIG. 2A. [Figure 3] FIG. 3 is a schematic diagram showing an example of the configuration of a fuel cell. [Figure 4] FIG. 4 is a perspective view schematically showing an example of a wound body. [Figure 5] FIG. 5 is a perspective view schematically showing a part of the manufacturing process of a fuel cell. [Figure 6] FIG. 6 is a perspective view schematically showing a method for evaluating winding property.

[0018] (Detailed Description of the Invention) The conductive nonwoven fabric of the present invention will be described in detail below. However, the present invention is not limited to the following configurations and can be modified and applied as appropriate without altering the essence of the invention. Furthermore, a combination of two or more of the individual preferred configurations of the present invention described below also constitutes the present invention.

[0019] The conductive nonwoven fabric of the present invention is a conductive nonwoven fabric used in the gas diffusion layer of a fuel cell, and is characterized in that the conductive nonwoven fabric contains organic fibers and a conductive substance.

[0020] The organic fibers constituting the conductive nonwoven fabric may or may not be conductive themselves. Organic fibers are more flexible than carbon fibers, and bending them does not easily cause breakage or cracking. Therefore, conductive nonwoven fabrics using organic fibers have excellent flexibility and winding properties.

[0021] The organic fiber is preferably at least one selected from the group consisting of polyamide fibers, polyester fibers, acrylic fibers, polyolefin fibers, polyvinyl alcohol fibers, aramid fibers, polyimide fibers, PBO fibers, and PPS fibers. Furthermore, polyethylene terephthalate (PET) is preferred as the polyester fiber. Furthermore, polyethylene fibers and polypropylene fibers are preferred as polyolefin fibers. When carbon fibers are used as a material for conductive nonwoven fabrics, high-temperature firing is required during the carbon fiber manufacturing process. However, these organic fibers do not require high-temperature firing during the fiber manufacturing process, making them preferable from the viewpoint of reducing CO2 emissions.

[0022] Furthermore, the organic fiber is preferably at least one selected from the group consisting of cellulose fiber, aliphatic polyester fiber, aliphatic polyamide fiber, recycled polyethylene terephthalate fiber, and polybutylene succinate fiber. Organic fibers are preferable because they do not require high-temperature firing during the fiber manufacturing process, thus reducing CO2 emissions. Furthermore, their raw materials are plant-derived or biodegradable, thus reducing the environmental burden.

[0023] The average fiber length of the organic fibers is preferably 20 mm or more, and the average fiber diameter is preferably 1 to 50 μm. If the average fiber length of the organic fibers is within the above range, it is longer than the average fiber length of the carbon fibers typically used in gas diffusion layers. It is thought that the longer fibers become intertwined, making the material more resistant to bending.

[0024] The conductive material is preferably a carbon-based material or a metal. The carbon-based material is preferably at least one selected from the group consisting of graphite, carbon black, carbonaceous milled fibers, and carbon nanotubes. Furthermore, the graphite is preferably expanded graphite or flaky graphite. The metal is preferably at least one selected from the group consisting of gold, silver, copper, platinum, palladium, aluminum, nickel, chromium, and zinc.

[0025] The shape of the conductive material is not particularly limited; it may be particulate, short fibrous, or film-like. When the conductive material is particulate, its average particle size is preferably 1.0 to 100 nm.

[0026] The thickness of the conductive nonwoven fabric is preferably 0.01 to 1.00 mm, more preferably 0.03 to 0.80 mm, and even more preferably 0.04 to 0.15 mm. If the thickness is too thick, the winding properties will decrease, and if the thickness is too thin, the strength will be insufficient and the conductive nonwoven fabric may break.

[0027] The surface density of conductive nonwoven fabrics is 2.0 to 100.0 g / m². 2Preferably, it is 5.0 to 80.0 g / m². 2 It is more preferable that the amount be 10.0 to 35.0 g / m². 2 It is even more preferable that this be the case. Furthermore, the bulk density of conductive nonwoven fabric is 0.100 to 0.500 g / cm³. 3 Preferably, it is 0.150 to 0.400 g / cm³. 3 It is more preferable that the concentration be 0.200-0.300 g / cm³. 3 It is even more preferable that this be the case.

[0028] In order for conductive nonwoven fabrics to function as a gas diffusion layer, it is preferable that they have a porosity of 65% or higher. The porosity P of the nonwoven fabric can be calculated using the following formula. P = (1 - FG / (d·ρ))·100 In the formula, FG is the surface specific gravity (unit: g / m³). 2 ), d is the thickness (in meters), and ρ is the true density of the conductive fibers (in grams / m³). 3 )

[0029] The conductive nonwoven fabric preferably has a volume resistivity of 1.0 Ω·cm or less. The volume resistivity of conductive nonwoven fabrics can be measured using the four-probe method in accordance with JIS K7194. The low volume resistivity ensures sufficient conductivity for the gas diffusion layer, allowing it to function effectively as an electron pathway.

[0030] The conductive nonwoven fabric is preferably designed to be wrapable without cracking when wrapped around a cylinder with a diameter of 20 mm. The wrapability can be evaluated by wrapping the conductive nonwoven fabric around a cylinder of a predetermined diameter and visually observing whether or not cracks occur.

[0031] Hereinafter, specific embodiments of the conductive nonwoven fabric of the present invention will be described, specifically a conductive nonwoven fabric obtained by a papermaking method and a conductive nonwoven fabric obtained by attaching a conductive substance to an organic nonwoven fabric.

[0032] (Conductive nonwoven fabric obtained by papermaking) Figure 1 is a schematic perspective view showing an example of a conductive nonwoven fabric that has been manufactured using papermaking techniques. The conductive nonwoven fabric 1 shown in Figure 1 is a papermaking product of a mixture of organic fibers and a conductive substance, in which particles of the conductive substance 20 are attached to the organic fibers 10. The organic fiber 10 and the conductive material 20 can be materials with the specifications described above. When the conductive substance 20 adheres to the organic fiber 10, the organic fiber 10 becomes a conductive fiber, and the nonwoven fabric, which is a papermaking product of the conductive fiber, becomes a conductive nonwoven fabric 1. As the particles of the conductive material 20, the carbon-based material or metal particles described above can be used. There may be one type of particle or multiple types of particles.

[0033] A method for producing a conductive nonwoven fabric made from paper is characterized by including a step of papermaking a mixture of organic fibers and a conductive substance. The method for manufacturing the conductive nonwoven fabric is one embodiment of the method for manufacturing the conductive nonwoven fabric of the present invention.

[0034] The above mixture is a mixture of organic fibers and a conductive material. In papermaking, a papermaking slurry is prepared containing water or another solvent in addition to the organic fibers and conductive material, and papermaking is carried out. In the above mixture, when the total weight of organic fibers and conductive material is taken as 100% by weight, the proportion of organic fibers is preferably 70.0 to 99.7% by weight, and the proportion of conductive material is preferably 0.3 to 30.0% by weight. Furthermore, the above mixture may also contain a dispersant, an inorganic binder, an organic binder, and the like.

[0035] (Conductive nonwoven fabric obtained by attaching a conductive substance to the organic fibers that make up the organic nonwoven fabric) Figure 2A is a schematic perspective view showing an example of an organic nonwoven fabric. Figure 2B is a schematic perspective view showing an example of a conductive nonwoven fabric in which a conductive substance is attached to the organic fibers that make up the organic nonwoven fabric shown in Figure 2A. The organic nonwoven fabric 30 shown in Figure 2A is made of organic fibers 10. In the conductive nonwoven fabric 2 shown in Figure 2B, a film of conductive substance 40 is attached to the organic fibers 10 that make up the organic nonwoven fabric 30, so that the organic fibers are conductive fibers. Figure 2B shows the organic fiber 10, which is visible on the near side of Figure 2B, as it is permeated through a portion of the conductive material 40 film. The organic fiber 10 and the conductive material 40 can be materials with the specifications described above. Preferably, the conductive material 40 is attached to the surface of the organic fibers 10 constituting the organic nonwoven fabric 30 by impregnation, vapor deposition, plating, sputtering, spray coating, or printing.

[0036] As the conductive material 40, the conductive material attached to the surface of the organic fibers 10 constituting the organic nonwoven fabric 30 by impregnating the organic nonwoven fabric 30 with a solution containing the conductive material can be used. In this case, the conductive material 40 can be the carbon-based material or metal described above, and there may be one type or more types. Furthermore, as the conductive material 40, a metal film formed on the surface of the organic fibers 10 constituting the organic nonwoven fabric 30 by vapor deposition, plating, sputtering, spray coating, or printing can be used. In this case, the conductive material is preferably a metal, and there may be one type or more types.

[0037] When a conductive substance is attached to the organic fibers that make up the organic nonwoven fabric, the organic fibers become conductive fibers, and the organic nonwoven fabric becomes a conductive nonwoven fabric.

[0038] The method for producing the conductive nonwoven fabric is characterized by including a step of attaching a conductive substance to the surface of the organic fibers constituting the organic nonwoven fabric by impregnation, vapor deposition, plating, sputtering, spray coating, or printing. Printing methods include roller coating and screen printing. The method for manufacturing the conductive nonwoven fabric is another embodiment of the method for manufacturing the conductive nonwoven fabric of the present invention.

[0039] (Fuel cell and gas diffusion layer) The conductive nonwoven fabric of the present invention is a conductive nonwoven fabric used in the gas diffusion layer of a fuel cell. The fuel cell preferably includes the conductive nonwoven fabric of the present invention as the gas diffusion layer of the fuel electrode and / or the gas diffusion layer of the air electrode.

[0040] The following describes an example of a fuel cell and a gas diffusion layer for a fuel cell. Figure 3 is a schematic diagram showing an example of a fuel cell configuration. In the fuel cell 100, hydrogen 210 is supplied to the fuel electrode 200, and in the catalyst layer 220, the hydrogen 210 is separated into hydrogen ions 230 and electrons 240 by a catalyst (platinum). Hydrogen ions 230 pass through the electrolyte membrane 250 and move to the air electrode 300. Electrons 240 escape to the outside and travel along the wire, becoming an electric current. Air containing oxygen 310 is introduced into the air electrode 300. In the catalyst layer 320, water 330 is produced by a reaction between oxygen 310, hydrogen ions 230 that have entered through the electrolyte membrane 250, and electrons 240 that have come via an external wire.

[0041] The fuel cell 100 described above is equipped with a fuel electrode-side gas diffusion layer 260 on the fuel electrode 200 and an air electrode-side gas diffusion layer 360 on the air electrode 300. The gas diffusion layer plays a role in the diffusion of the fuel hydrogen 210 and oxygen 310 (air), supplying them to the catalyst layer 220 and catalyst layer 320, collecting electrons 240 generated by the chemical reaction in the catalyst layer 220, and discharging water 330 generated in the reaction in the catalyst layer 320.

[0042] (Wrap-around type) The conductive nonwoven fabric of the present invention may be in the form of a wound body wound around a roll. By winding the conductive nonwoven fabric onto a roll, it becomes a form suitable for the manufacture of fuel cells.

[0043] Figure 4 is a schematic perspective view showing an example of a winding body. The winding body 400 shown in Figure 4 is formed by winding a conductive nonwoven fabric 1 around a core material 410. The circle indicated by the dotted line in Figure 4 shows an enlarged view of the conductive nonwoven fabric 1 that constitutes the wrapped body 400.

[0044] The outer diameter of the core material is not particularly limited, but from the viewpoint of increasing the winding length of the conductive nonwoven fabric per winding, a smaller outer diameter of the core material is preferable, preferably 40 mm or less. Since the outer diameter of the core material matches the inner diameter of the conductive nonwoven fabric roll, it can also be said that it is preferable for the inner diameter of the conductive nonwoven fabric roll to be 40 mm or less. The conductive nonwoven fabric of the present invention is less prone to breakage of conductive fibers during winding and has excellent winding properties, so even if the outer diameter of the core material is 40 mm or less (the inner diameter of the roll of conductive nonwoven fabric is 40 mm or less), a wound body can be obtained without causing breakage of conductive fibers. Furthermore, it is preferable that the outer diameter of the core material (the inner diameter of the roll of conductive nonwoven fabric) be 10 mm or more. Furthermore, if the winding material does not pose any problems in maintaining the shape of the winding body or in the manufacturing process of the fuel cell, then the winding body does not need to have a core material.

[0045] Figure 4 shows conductive nonwoven fabric 1, which is a papermaking product as shown in Figure 1, as the conductive nonwoven fabric constituting the winding body. However, the conductive nonwoven fabric constituting the winding body may also be conductive nonwoven fabric 2, which is obtained by attaching a conductive substance to the organic nonwoven fabric shown in Figure 2B.

[0046] (Method of manufacturing fuel cells) It is preferable to manufacture a fuel cell using a winding in which the conductive nonwoven fabric of the present invention is wound onto a roll. A method for manufacturing a fuel cell using a winding body in which the conductive nonwoven fabric of the present invention is wound around a roll preferably includes a step of continuously supplying the conductive nonwoven fabric that will become the gas diffusion layer from the winding body to form a catalyst layer on the conductive nonwoven fabric.

[0047] Figure 5 is a schematic perspective view showing part of the fuel cell manufacturing process. In the process shown in Figure 5, a winding body 400, in which conductive nonwoven fabric is wound around a roll, is used as the supply-side roll 510. The conductive nonwoven fabric 1, which will become the gas diffusion layer, is continuously supplied, and the catalyst layer paste 540 is applied using the coating device 530. The catalyst layer paste 540 is dried with a heater 550 to form the catalyst layer, and then wound up on the winding-side roll 520. In fuel cell manufacturing methods that include such processes, the productivity of fuel cells can be improved by continuously performing the lamination process of the gas diffusion layer and other layers. The conductive nonwoven fabric of the present invention is suitable for use in the manufacturing process of the fuel cell because it is suitable for supply in the form of a wound body wound on a roll.

[0048] (Examples) The following are examples that more specifically disclose the present invention. However, the present invention is not limited to these examples.

[0049] (Example 1) We prepared polyethylene terephthalate (PET) nonwoven fabric (Milife TY1515FE: manufactured by ENEOS Techno Material Co., Ltd.) as the organic nonwoven fabric. Platinum was deposited onto this organic nonwoven fabric using a sputtering apparatus (JEOL Ltd.: JFC-1600) under conditions of a sputtering current of 30 mA and a processing time of 30 minutes to create a conductive nonwoven fabric.

[0050] (Examples 2 and 3) In Example 2, polyethylene terephthalate (PET) nonwoven fabric (Milife TY1010FE: manufactured by ENEOS Techno Material Co., Ltd.) was prepared as the organic nonwoven fabric, and in Example 3, polyethylene terephthalate (PET) nonwoven fabric (Milife TY0505FE: manufactured by ENEOS Techno Material Co., Ltd.) was prepared as the organic nonwoven fabric. A platinum film was formed in the same manner as in Example 1 to obtain a conductive nonwoven fabric. The average fiber diameter of the organic nonwoven fabrics prepared in Examples 1-3 was 10 μm, and the sample size was 50 mm x 50 mm.

[0051] Table 1 shows the specifications of the organic nonwoven fabric before film formation and the specifications of the conductive nonwoven fabric after film formation in Examples 1 to 3.

[0052] [Table 1]

[0053] (Comparative Example 1) Conductive sheets obtained by impregnating carbon fibers (indicated as CF in Table 2) with resin and firing were prepared as evaluation sheets. Their specifications are shown in Table 2.

[0054] (Comparative Example 2) For Comparative Example 2, a sheet of the organic nonwoven fabric prepared in Example 1, without the formation of a platinum film, was prepared.

[0055] (Evaluation of wrapping ability) Figure 6 is a schematic perspective view illustrating the method for evaluating wrapability. Cylinders with diameters ranging from 20 mm to 35 mm were prepared, and the conductive nonwoven fabric obtained in each example was processed to a length of 50 mm and a width of 10 mm to create evaluation sheets. Similarly, evaluation sheets for each comparative example were processed to the same size. As shown in Figure 6, the evaluation sheet 610 was wrapped around the cylinder 600, and the presence of cracks in the evaluation sheet was visually observed. The wrapping direction was such that the 50 mm long side was in the wrapping direction (direction of the arrow in Figure 6). The wrapping properties are so good that the evaluation sheet can be wrapped around even small diameter cylinders without cracking. The evaluation results are shown in Table 2.

[0056] (Evaluation of volume resistivity) The volume resistivity of the conductive nonwoven fabrics obtained in each example and the evaluation sheets prepared in each comparative example (all 50 mm x 50 mm in size) was evaluated using the four-probe method in accordance with JIS K7194. The device used was the Rolester GP MCP-T610 (manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and the probe used was the ASP probe MCP-TP03P. We measured five points on each sheet at a voltage of 10V and calculated the average value. The evaluation results are shown in Table 2.

[0057] [Table 2]

[0058] As shown in Table 2, the conductive nonwoven fabrics of Examples 1-3 exhibited excellent winding properties. Furthermore, their volume resistivity was also low. The evaluation sheet for Comparative Example 1 was made of carbon fiber, and therefore had poor winding properties. The evaluation sheet in Comparative Example 2 was an organic nonwoven fabric that had not undergone any treatment to impart conductivity, and therefore had a high volume resistivity. As it was not a conductive nonwoven fabric, it was unsuitable for use as a gas diffusion layer. [Explanation of symbols]

[0059] 1, 2 Conductive nonwoven fabric 10 Organic Fibers 20 Conductive substances (particles) 30 Organic non-woven fabric 40 Conductive material (film) 100 fuel cell 200 Fuel electrode 210 Hydrogen 220 Catalyst layer 230 hydrogen ions 240 electronic 250 Electrolyte membrane 260 Fuel electrode side gas diffusion layer 300 Air pole 310 Oxygen 320 Catalyst layer 330 water 360 Air electrode side gas diffusion layer 400 wrapped body 410 Core material 510 Supply side roll 520 Take-up side roll 530 Coating equipment 540 Catalyst layer paste 550 Heater 600 cylinder 610 Evaluation Sheet

Claims

1. A conductive nonwoven fabric used in the gas diffusion layer of a fuel cell, The conductive nonwoven fabric consists of an organic nonwoven fabric made of organic fibers and a conductive substance which is a metal film directly provided on the surface of the organic fibers constituting the organic nonwoven fabric. A conductive nonwoven fabric characterized in that the surface specific gravity of the conductive nonwoven fabric is 10 to 35 g / m².

2. The conductive nonwoven fabric according to claim 1, wherein the conductive substance is directly attached to the surface of the organic fibers constituting the organic nonwoven fabric by vapor deposition, plating, sputtering, spray coating, or printing.

3. The conductive nonwoven fabric according to claim 1 or 2, wherein the organic fiber is at least one selected from the group consisting of polyamide fiber, polyester fiber, acrylic fiber, polyolefin fiber, polyvinyl alcohol fiber, aramid fiber, polyimide fiber, PBO fiber, and PPS fiber.

4. The conductive nonwoven fabric according to claim 1 or 2, wherein the organic fiber is at least one selected from the group consisting of cellulose fiber, aliphatic polyester fiber, aliphatic polyamide fiber, recycled polyethylene terephthalate fiber, and polybutylene succinate fiber.

5. The conductive nonwoven fabric according to any one of claims 1 to 4, wherein the conductive material is at least one selected from the group consisting of gold, silver, copper, platinum, palladium, aluminum, nickel, chromium, and zinc.

6. A method for producing a conductive nonwoven fabric having a surface density of 10 to 35 g / m², used as a gas diffusion layer in a fuel cell, characterized by including a step of directly forming a metal film on the surface of the organic fibers constituting the organic nonwoven fabric by vapor deposition, plating, sputtering, spray coating, or printing.

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