A gas diffusion layer material for fuel cell and preparation method thereof

Abstract

The present invention discloses a gas diffusion layer material for fuel cells and a preparation method thereof, and relates to the field of fuel cells. When preparing the gas diffusion layer material for fuel cells, the present invention comprises the following steps: oxidizing a carbon paper substrate with nitric acid and sulfuric acid to produce a carboxylated carbon paper substrate; polymerizing and depositing maleic anhydride, styrene, and 3-nitrostyrene on the surface of acetylene black to produce modified acetylene black; treating polytetrafluoroethylene powder and sequentially grafting 3,4-epoxy-1-butene and aniline to produce modified polytetrafluoroethylene; mixing the modified acetylene black and the modified polytetrafluoroethylene and spraying them on the carboxylated carbon paper substrate, followed by sintering and sealing to produce the gas diffusion layer material; cross-linking the gas diffusion layer material with 3,3'-diaminobenzidine and grafting polyaniline to produce the gas diffusion layer material for fuel cells. The gas diffusion layer material for fuel cells prepared by the present invention has excellent electrical conductivity, air permeability, and mechanical properties.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells, and in particular to a gas diffusion layer material for fuel cells and a preparation method thereof. Background Art

[0002] In recent years, the global energy supply has largely relied on fossil fuels, such as oil, coal or natural gas. The over-exploitation and consumption of these resources have led to a global energy crisis. Hydrogen energy, as a clean energy, has become a key force in the global energy transformation. Among them, fuel cells, as the best way to efficiently and cleanly utilize hydrogen energy, have high energy density and do not produce greenhouse gases or other harmful emissions. They have gradually become a hot topic of research. With the continuous advancement of technology and the gradual maturity of the market, fuel cells are becoming increasingly important in the global energy structure, providing strong support for the sustainable development of mankind. As an important component of the fuel cell, the gas diffusion layer plays the role of supporting the catalytic layer and collecting current, and is an important transmission channel for the reaction gas and product water. Therefore, the present invention prepares a gas diffusion layer material for fuel cells with excellent air permeability. Summary of the Invention

[0003] The object of the present invention is to provide a gas diffusion layer material for a fuel cell and a preparation method thereof, so as to solve the problems existing in the prior art.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] A gas diffusion layer material for a fuel cell is prepared by cross-linking a gas diffusion layer material with 3,3'-diaminobenzidine and then grafting polyaniline onto the cross-linked gas diffusion layer material.

[0006] As an optimization, the gas diffusion layer material is prepared by mixing modified acetylene black and modified polytetrafluoroethylene, spraying the mixture on a carboxylated carbon paper substrate, and then sintering and sealing the pores.

[0007] As an optimization, the modified acetylene black is prepared by polymerizing maleic anhydride, styrene and 3-nitrostyrene and depositing them on the surface of acetylene black.

[0008] As an optimization, the acetylene black model is 600 mesh and is from Ruiyat (Tianjin) Chemical Co., Ltd.

[0009] As an optimization, the modified polytetrafluoroethylene is prepared by treating polytetrafluoroethylene powder and then grafting 3,4-epoxy-1-butene and aniline in sequence.

[0010] As an optimization, the polytetrafluoroethylene powder is of extrusion grade and comes from Dongguan Sancheng Plastic Raw Materials Co., Ltd.

[0011] As an optimization, the carboxylated carbon paper base layer is prepared by oxidation of the carbon paper base layer with nitric acid and sulfuric acid.

[0012] As an optimization, the carbon paper base layer model is YLS30T, which comes from Suzhou Shengernuo Technology Co., Ltd.

[0013] A method for preparing a gas diffusion layer material for a fuel cell comprises the following steps:

[0014] (1) Nitric acid and sulfuric acid are mixed in a volume ratio of 1:(2-4) to obtain a mixed acid solution; the carbon paper substrate is immersed in the mixed acid solution, evaporated and refluxed at 75-85°C for 11-13 hours, washed with deionized water and anhydrous ethanol for 3-5 times, and dried at 60-70°C for 9-11 hours to obtain an oxidized carbon paper substrate; the oxidized carbon paper substrate is immersed in a 1%-3% chloroacetic acid aqueous solution, sodium hydroxide is added with a molar amount of 0.4-0.5 times the chloroacetic acid in the chloroacetic acid aqueous solution, ultrasonically dispersed for 25-35 minutes, taken out and aired until no liquid drops within 5-15 seconds, allowed to stand at 30-40°C for 5-7 hours, washed with a 36%-38% hydrochloric acid solution and deionized water for 3-5 times, and dried at 60-70°C for 11-13 hours to obtain a carboxylated carbon paper substrate;

[0015] (2) Acetylene black, maleic anhydride, styrene, 3-nitrostyrene, azobisisobutyronitrile and isoamyl acetate were mixed in a mass ratio of 1:(1-3):(0.9-1.1):(0.6-0.7):(0.03-0.04):(14-16), ultrasonically dispersed for 20-30 min, stirred at 70-80 °C and 200-400 rpm for 7-9 h in a nitrogen atmosphere, cooled naturally to room temperature and centrifuged, washed with isoamyl acetate and petroleum ether for 3-5 times respectively, and dried at 50-60 °C for 11-13 h to obtain modified acetylene black;

[0016] (3) Treat polytetrafluoroethylene powder in an argon atmosphere at a voltage of 35~45V for 200~400s, let it stand for 5~15min to obtain pre-treated polytetrafluoroethylene; mix pre-treated polytetrafluoroethylene, 3,4-epoxy-1-butene, benzoyl peroxide and chlorobenzene in a mass ratio of 1:(1.3~1.5):(0.06~0.08):(3~5), stir in a nitrogen atmosphere at 85~95℃ and 300~400rpm for 4~6h, and cool naturally to room temperature. The pre-modified polytetrafluoroethylene was centrifuged, washed with acetone and deionized water for 3 to 5 times, and dried at 55 to 65°C for 23 to 25 hours to obtain pre-modified polytetrafluoroethylene; the pre-modified polytetrafluoroethylene was immersed in an aniline ethanol solution with a volume fraction of 55% to 65%, sonicated for 20 to 30 minutes, taken out and aired until no liquid droplets fell within 5 to 15 seconds, and allowed to stand at 55 to 65°C in a nitrogen atmosphere for 5 to 7 hours, washed with deionized water for 3 to 5 times, and dried at 65 to 75°C for 8 to 10 hours to obtain modified polytetrafluoroethylene;

[0017] (4) Modified acetylene black, modified polytetrafluoroethylene and anhydrous ethanol were mixed in a mass ratio of 1: (0.2~0.3): (3~5), ultrasonically dispersed for 25~35 minutes, stirred at 200~300rpm for 25~35 minutes, and repeated ultrasonic stirring for 4~6 times to obtain a microporous layer spray liquid; aluminum phosphate and anhydrous ethanol were mixed in a mass ratio of 1: (14~16), ultrasonically dispersed to obtain a sealing liquid; the microporous layer spray liquid was sprayed on the carboxylated carbon paper substrate heated by an electric heating plate with a spray gun to a thickness of 100%. The particle size is 40-60 μm, and the particle size is transferred into a tube furnace, heated to 240-260°C at a rate of 4-6°C / min, baked for 25-35 min, and then heated to 340-360°C at a rate of 1-3°C / min, sintered for 25-35 min, and then cooled to room temperature at a rate of 4-6°C / min, taken out, ultrasonicated in a sealing liquid for 20-30 min, taken out, washed with deionized water for 3-5 times, and dried at 65-75°C for 9-11 h to obtain a gas diffusion layer material;

[0018] (5) Immerse the gas diffusion layer material in a 32% to 34% by mass 3,3'-diaminobenzidine N,N-dimethylacetamide solution, ultrasonically disperse for 25 to 35 minutes, take it out and let it air dry until no liquid drops fall within 5 to 15 seconds, stand it in a nitrogen atmosphere at 135 to 145 ° C for 2 to 4 hours, heat it to 185 to 195 ° C and stand it for 15 to 20 hours, cool it naturally to room temperature, wash it with deionized water 3 to 5 times, and freeze it at 75 to drying at 85° C. for 6 to 8 hours to obtain a pre-modified gas diffusion layer material; mixing sodium sulfide, sodium carbonate, and deionized water in a mass ratio of 1:(0.7 to 0.9):(35 to 45) to obtain a reaction solution; immersing the pre-modified gas diffusion layer material in the reaction solution, standing at 95 to 105° C. for 20 to 30 minutes, then taking it out, washing it with deionized water 3 to 5 times, and drying it at 65 to 75° C. for 9 to 11 hours to obtain an amino-modified gas diffusion layer material;

[0019] (6) Aniline and 0.9~1.1mol / L hydrochloric acid solution were mixed at a mass ratio of 1:(26~28) to obtain aniline hydrochloric acid solution; ammonium persulfate and 0.9~1.1mol / L hydrochloric acid solution were mixed at a mass ratio of 1:(10~12) to obtain ammonium persulfate hydrochloric acid solution; the amino-treated gas diffusion layer material was immersed in the aniline hydrochloric acid solution, ultrasonicated for 20~30min, and an ammonium persulfate hydrochloric acid solution of equal volume to the aniline hydrochloric acid solution was added, ultrasonicated for 20~30min, taken out and aired until no liquid droplets fell within 5~15s, and allowed to stand at -1~1℃ for 1~3h, and washed with 0.9~1.1mol / L hydrochloric acid solution and methanol for 3~5 times respectively, ultrasonicated in a hydrochloric acid solution with a mass fraction of 36%~38% for 1~3h, washed with deionized water for 3~5 times, and dried at 65~75℃ for 8~10h to obtain a gas diffusion layer material for fuel cells.

[0020] As an optimization, the reaction equation for the carboxylation of the carbon paper substrate in step (1) is:

[0021] .

[0022] As an optimization, the reaction equation of the modified acetylene black in step (2) is:

[0023] .

[0024] As an optimization, the reaction equation for the modified polytetrafluoroethylene in step (3) is:

[0025] .

[0026] As an optimization, the reaction equation for the amination of the gas diffusion layer material in step (5) is:

[0027] .

[0028] As an optimization, the reaction equation of the gas diffusion layer material for the fuel cell in step (6) is:

[0029] .

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] In the preparation of a gas diffusion layer material for a fuel cell, the present invention comprises the following steps: subjecting a carbon paper base layer to oxidation with nitric acid and sulfuric acid and then reacting to obtain a carboxylated carbon paper base layer; polymerizing and depositing maleic anhydride, styrene and 3-nitrostyrene on the surface of acetylene black to obtain modified acetylene black; treating polytetrafluoroethylene powder and then sequentially grafting 3,4-epoxy-1-butene and aniline to obtain modified polytetrafluoroethylene; uniformly mixing the modified acetylene black and the modified polytetrafluoroethylene and then spraying the mixture on the carboxylated carbon paper base layer, followed by sintering and sealing to obtain a gas diffusion layer material; and cross-linking the gas diffusion layer material with 3,3'-diaminobenzidine and then grafting polyaniline to obtain a gas diffusion layer material for a fuel cell.

[0032] First, a carbon paper substrate is oxidized with nitric acid and sulfuric acid to obtain a carboxylated carbon paper substrate; maleic anhydride, styrene and 3-nitrostyrene are polymerized and deposited on the surface of acetylene black to obtain modified acetylene black; polytetrafluoroethylene powder is treated and then grafted with 3,4-epoxy-1-butene and aniline in sequence to obtain modified polytetrafluoroethylene; nitric acid and sulfuric acid are used to oxidize to form oxygen-containing groups such as carboxyl and hydroxyl, and then chloroacetic acid is used to convert the oxygen-containing groups into carboxyl groups, which are grafted with 3,3'-diaminobenzidine and condensed to obtain benzimidazole rings, forming dense and stable molecular chains, thereby improving the mechanical properties of gas diffusion layer materials for fuel cells; maleic anhydride, styrene and 3-nitrostyrene are used in acetylene to form a carbon paper substrate ... Black surface polymerization deposition introduces an anhydride structure, which reacts with 3,3'-diaminobenzidine to form a stable π-electron conjugated structure, enhancing structural stability, promoting electron transfer, and improving the mechanical properties and conductivity of the gas diffusion layer material for fuel cells; 3,4-epoxy-1-butene is grafted onto the surface of polytetrafluoroethylene through plasma activation, and aniline is grafted using the epoxy ring-opening reaction. Aniline is oxidatively polymerized to form conjugated long chains, forming a cross-linked network, thereby improving the mechanical properties and conductivity of the gas diffusion layer material for fuel cells; at the same time, the hydroxyl groups formed by the epoxy ring opening can be removed during the subsequent sintering process to form pores, thereby improving the permeability of the gas diffusion layer material for fuel cells.

[0033] Secondly, modified acetylene black and modified polytetrafluoroethylene are mixed and sprayed on a carboxylated carbon paper base, and then sintered and sealed to obtain a gas diffusion layer material; the gas diffusion layer material is then cross-linked with 3,3'-diaminobenzidine and grafted with polyaniline to obtain a gas diffusion layer material for fuel cells; an electric heating plate is used to accelerate the volatilization rate of anhydrous ethanol during the spraying process to avoid particle agglomeration and the formation of tiny pores, thereby improving the permeability of the gas diffusion layer material for fuel cells; aluminum phosphate is used to seal the pores, which is then dissolved in concentrated hydrochloric acid and then pores are formed to increase the pore structure and further improve the porosity of the high-porosity gas diffusion layer carbon paper; sodium sulfide is used to reduce the nitro group on the surface of the modified acetylene black, increase the reactive sites of polyaniline, enrich the cross-linking network, and improve the mechanical properties and conductivity of the gas diffusion layer material for fuel cells. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] The raw materials used in the following examples and comparative examples are all commercially available:

[0036] The acetylene black model is 600 mesh and is from Ruiyat (Tianjin) Chemical Co., Ltd.

[0037] The polytetrafluoroethylene powder is extrusion grade and comes from Dongguan Sancheng Plastic Raw Materials Co., Ltd.

[0038] The carbon paper base layer is model YLS30T, which comes from Suzhou Shengernuo Technology Co., Ltd. Example 1

[0039] A method for preparing a gas diffusion layer material for a fuel cell, the method comprising the following steps:

[0040] (1) Nitric acid and sulfuric acid were mixed in a volume ratio of 1:2 to obtain a mixed acid solution; the carbon paper substrate was immersed in the mixed acid solution, evaporated and refluxed at 75°C for 13 hours, washed with deionized water and anhydrous ethanol three times respectively, and dried at 60°C for 11 hours to obtain an oxidized carbon paper substrate; the oxidized carbon paper substrate was immersed in a 1% chloroacetic acid aqueous solution, and sodium hydroxide with a molar amount of 0.4 times that of chloroacetic acid in the chloroacetic acid aqueous solution was added, ultrasonically dispersed for 25 minutes, taken out and aired until no liquid dripped within 5 seconds, allowed to stand at 30°C for 7 hours, washed with a 36% hydrochloric acid solution and deionized water three times respectively, and dried at 60°C for 13 hours to obtain a carboxylated carbon paper substrate;

[0041] (2) Acetylene black, maleic anhydride, styrene, 3-nitrostyrene, azobisisobutyronitrile and isoamyl acetate were mixed in a mass ratio of 1:1:0.9:0.6:0.03:14, ultrasonically dispersed for 20 min, stirred at 70 °C and 200 rpm for 9 h in a nitrogen atmosphere, cooled naturally to room temperature and centrifuged, washed with isoamyl acetate and petroleum ether three times respectively, and dried at 50 °C for 13 h to obtain modified acetylene black;

[0042] (3) Treating polytetrafluoroethylene powder in an argon atmosphere at a voltage of 35 V for 400 s, and letting it stand for 5 min to obtain pre-treated polytetrafluoroethylene; mixing pre-treated polytetrafluoroethylene, 3,4-epoxy-1-butene, benzoyl peroxide and chlorobenzene in a mass ratio of 1:1.3:0.06:3, stirring at 85 ° C and 300 rpm for 6 h in a nitrogen atmosphere, naturally cooling to room temperature and centrifuging, washing with acetone and deionized water three times respectively, and drying at 55 ° C for 25 h to obtain pre-modified polytetrafluoroethylene; immersing the pre-modified polytetrafluoroethylene in a 55% volume fraction aniline ethanol solution, ultrasonicating for 20 min, taking it out and airing it until no liquid drops within 5 s, letting it stand at 55 ° C for 7 h in a nitrogen atmosphere, washing with deionized water three times, and drying at 65 ° C for 10 h to obtain modified polytetrafluoroethylene;

[0043] (4) Modified acetylene black, modified polytetrafluoroethylene and anhydrous ethanol were mixed in a mass ratio of 1:0.2:3, ultrasonically dispersed for 25 minutes, stirred at 200 rpm for 35 minutes, and ultrasonically stirred for 4 times to obtain a microporous layer spray liquid; aluminum phosphate and anhydrous ethanol were mixed in a mass ratio of 1:14, ultrasonically dispersed to obtain a sealing liquid; the microporous layer spray liquid was sprayed on a carboxylated carbon paper substrate heated on an electric hot plate with a spray gun to a thickness of 40 μm, moved into a tube furnace, heated to 240°C at a rate of 4°C / min and baked for 35 minutes, continued to heat to 340°C at a rate of 1°C / min and sintered for 35 minutes, then cooled to room temperature at a rate of 4°C / min and taken out, ultrasonically soaked in the sealing liquid for 20 minutes, taken out, washed 3 times with deionized water, and dried at 65°C for 11 hours to obtain a gas diffusion layer material;

[0044] (5) The gas diffusion layer material was immersed in a 32% by mass 3,3'-diaminobenzidine N,N-dimethylacetamide solution, ultrasonically dispersed for 25 minutes, taken out and aired until no liquid droplets fell within 5 seconds, and allowed to stand at 135 ° C in a nitrogen atmosphere for 4 hours, heated to 185 ° C and allowed to stand for 20 hours, cooled naturally to room temperature, washed with deionized water 3 times, and dried at 75 ° C for 8 hours to obtain a pre-modified gas diffusion layer material; sodium sulfide, sodium carbonate and deionized water were mixed in a mass ratio of 1:0.7:35 to obtain a reaction solution; the pre-modified gas diffusion layer material was immersed in the reaction solution, allowed to stand at 95 ° C for 30 minutes, taken out, washed with deionized water 3 times, and dried at 65 ° C for 11 hours to obtain an amino gas diffusion layer material;

[0045] (6) Aniline and 0.9 mol / L hydrochloric acid solution were mixed at a mass ratio of 1:26 to obtain aniline hydrochloric acid solution; ammonium persulfate and 0.9 mol / L hydrochloric acid solution were mixed at a mass ratio of 1:10 to obtain ammonium persulfate hydrochloric acid solution; the amino-treated gas diffusion layer material was immersed in the aniline hydrochloric acid solution, ultrasonicated for 20 minutes, and an ammonium persulfate hydrochloric acid solution of the same volume as the aniline hydrochloric acid solution was added, ultrasonicated for 20 minutes, taken out and aired until no liquid dripped within 5 seconds, allowed to stand at -1°C for 3 hours, washed with 0.9 mol / L hydrochloric acid solution and methanol for 5 times respectively, ultrasonicated in a 36% hydrochloric acid solution for 3 hours, washed with deionized water 3 times, and dried at 65°C for 10 hours to obtain a gas diffusion layer material for fuel cells. Example 2

[0046] A method for preparing a gas diffusion layer material for a fuel cell, the method comprising the following steps:

[0047] (1) Nitric acid and sulfuric acid were mixed in a volume ratio of 1:3 to obtain a mixed acid solution; the carbon paper substrate was immersed in the mixed acid solution, evaporated and refluxed at 80°C for 12 hours, washed with deionized water and anhydrous ethanol four times respectively, and dried at 65°C for 10 hours to obtain an oxidized carbon paper substrate; the oxidized carbon paper substrate was immersed in a 2% by mass aqueous solution of chloroacetic acid, sodium hydroxide with a molar amount of 0.45 times that of chloroacetic acid in the chloroacetic acid aqueous solution was added, ultrasonically dispersed for 30 minutes, taken out and aired until no liquid dripped within 10 seconds, allowed to stand at 35°C for 6 hours, washed with a 37% by mass hydrochloric acid solution and deionized water four times respectively, and dried at 65°C for 12 hours to obtain a carboxylated carbon paper substrate;

[0048] (2) Acetylene black, maleic anhydride, styrene, 3-nitrostyrene, azobisisobutyronitrile and isoamyl acetate were mixed in a mass ratio of 1:2:1:0.65:0.035:15, ultrasonically dispersed for 25 min, stirred at 75 ° C and 300 rpm for 8 h in a nitrogen atmosphere, cooled naturally to room temperature and centrifuged, washed with isoamyl acetate and petroleum ether four times respectively, and dried at 55 ° C for 12 h to obtain modified acetylene black;

[0049] (3) Treating polytetrafluoroethylene powder in an argon atmosphere at a voltage of 40 V for 300 s, and letting it stand for 10 min to obtain pre-treated polytetrafluoroethylene; mixing pre-treated polytetrafluoroethylene, 3,4-epoxy-1-butene, benzoyl peroxide and chlorobenzene in a mass ratio of 1:1.4:0.07:4, stirring at 90 ° C and 350 rpm for 5 h in a nitrogen atmosphere, naturally cooling to room temperature and centrifuging, washing with acetone and deionized water four times respectively, and drying at 60 ° C for 24 h to obtain pre-modified polytetrafluoroethylene; immersing the pre-modified polytetrafluoroethylene in a 60% volume fraction aniline ethanol solution, ultrasonicating for 25 min, taking it out and airing until no liquid drops within 10 s, letting it stand at 60 ° C in a nitrogen atmosphere for 6 h, washing with deionized water four times, and drying at 70 ° C for 9 h to obtain modified polytetrafluoroethylene;

[0050] (4) Modified acetylene black, modified polytetrafluoroethylene and anhydrous ethanol were mixed in a mass ratio of 1:0.25:4, ultrasonically dispersed for 30 minutes, stirred at 250 rpm for 30 minutes, and repeated ultrasonic stirring for 5 times to obtain a microporous layer spray liquid; aluminum phosphate and anhydrous ethanol were mixed in a mass ratio of 1:15, ultrasonically dispersed to obtain a sealing liquid; the microporous layer spray liquid was sprayed on a carboxylated carbon paper substrate heated on an electric hot plate with a spray gun to a thickness of 50 μm, moved into a tube furnace, heated to 250 ° C at a rate of 5 ° C / min and baked for 30 minutes, continued to heat to 350 ° C at a rate of 2 ° C / min and sintered for 30 minutes, and then cooled to room temperature at a rate of 5 ° C / min and taken out, ultrasonically soaked in the sealing liquid for 25 minutes, taken out, washed 4 times with deionized water, and dried at 70 ° C for 10 hours to obtain a gas diffusion layer material;

[0051] (5) The gas diffusion layer material was immersed in a 33% mass fraction of 3,3'-diaminobenzidine in N,N-dimethylacetamide solution, ultrasonically dispersed for 30 minutes, taken out and aired until no liquid droplets fell within 10 seconds, and allowed to stand at 140 ° C in a nitrogen atmosphere for 3 hours, heated to 190 ° C and allowed to stand for 17.5 hours, cooled naturally to room temperature, washed with deionized water 4 times, and dried at 80 ° C for 7 hours to obtain a pre-modified gas diffusion layer material; sodium sulfide, sodium carbonate and deionized water were mixed in a mass ratio of 1:0.8:40 to obtain a reaction solution; the pre-modified gas diffusion layer material was immersed in the reaction solution, allowed to stand at 100 ° C for 25 minutes, taken out, washed with deionized water 4 times, and dried at 70 ° C for 10 hours to obtain an amino gas diffusion layer material;

[0052] (6) Aniline and 1 mol / L hydrochloric acid solution were mixed at a mass ratio of 1:27 to obtain aniline hydrochloric acid solution; ammonium persulfate and 1 mol / L hydrochloric acid solution were mixed at a mass ratio of 1:11 to obtain ammonium persulfate hydrochloric acid solution; the amino-treated gas diffusion layer material was immersed in the aniline hydrochloric acid solution, ultrasonicated for 25 minutes, and an equal volume of ammonium persulfate hydrochloric acid solution was added, ultrasonicated for 25 minutes, taken out and aired until no liquid droplets fell within 10 seconds, allowed to stand at 0°C for 2 hours, washed with 1 mol / L hydrochloric acid solution and methanol respectively for 4 times, ultrasonicated in a 37% hydrochloric acid solution for 2 hours, washed with deionized water 4 times, and dried at 70°C for 9 hours to obtain a gas diffusion layer material for fuel cells. Example 3

[0053] A method for preparing a gas diffusion layer material for a fuel cell, the method comprising the following steps:

[0054] (1) Nitric acid and sulfuric acid were mixed in a volume ratio of 1:4 to obtain a mixed acid solution; the carbon paper substrate was immersed in the mixed acid solution, evaporated and refluxed at 85°C for 11 hours, washed with deionized water and anhydrous ethanol 5 times respectively, and dried at 70°C for 9 hours to obtain an oxidized carbon paper substrate; the oxidized carbon paper substrate was immersed in a 3% chloroacetic acid aqueous solution, and sodium hydroxide with a molar amount of 0.5 times that of chloroacetic acid in the chloroacetic acid aqueous solution was added, ultrasonically dispersed for 25 minutes, taken out and aired until no liquid dripped within 15 seconds, allowed to stand at 40°C for 5 hours, washed with a 38% hydrochloric acid solution and deionized water 3 times respectively, and dried at 70°C for 11 hours to obtain a carboxylated carbon paper substrate;

[0055] (2) Acetylene black, maleic anhydride, styrene, 3-nitrostyrene, azobisisobutyronitrile and isoamyl acetate were mixed in a mass ratio of 1:3:1.1:0.7:0.04:16, ultrasonically dispersed for 30 min, stirred at 80 ° C and 400 rpm for 7 h in a nitrogen atmosphere, cooled naturally to room temperature and centrifuged, washed with isoamyl acetate and petroleum ether for 5 times respectively, and dried at 60 ° C for 11 h to obtain modified acetylene black;

[0056] (3) Treating polytetrafluoroethylene powder in an argon atmosphere at 45V for 200s, and letting it stand for 15min to obtain pretreated polytetrafluoroethylene; mixing pretreated polytetrafluoroethylene, 3,4-epoxy-1-butene, benzoyl peroxide and chlorobenzene in a mass ratio of 1:1.5:0.08:5, stirring at 95℃ and 400rpm for 4h in a nitrogen atmosphere, cooling naturally to room temperature and centrifuging, washing with acetone and deionized water for 5 times respectively, and drying at 65℃ for 23h to obtain pre-modified polytetrafluoroethylene; immersing the pre-modified polytetrafluoroethylene in a 65% volume fraction aniline ethanol solution, ultrasonicating for 30min, taking it out and airing it until no liquid drops within 15s, letting it stand at 65℃ in a nitrogen atmosphere for 5h, washing with deionized water for 5 times, and drying at 75℃ for 8h to obtain modified polytetrafluoroethylene;

[0057] (4) Modified acetylene black, modified polytetrafluoroethylene and anhydrous ethanol were mixed in a mass ratio of 1:0.3:5, ultrasonically dispersed for 35 minutes, stirred at 300 rpm for 25 minutes, and ultrasonically stirred for 6 times to obtain a microporous layer spray liquid; aluminum phosphate and anhydrous ethanol were mixed in a mass ratio of 1:16, ultrasonically dispersed to obtain a sealing liquid; the microporous layer spray liquid was sprayed on a carboxylated carbon paper substrate heated on an electric hot plate with a spray gun to a thickness of 60 μm, moved into a tubular furnace, heated to 260°C at a rate of 6°C / min and baked for 25 minutes, continued to heat to 360°C at a rate of 3°C / min and sintered for 25 minutes, then cooled to room temperature at a rate of 6°C / min and taken out, ultrasonically soaked in the sealing liquid for 30 minutes, taken out, washed 5 times with deionized water, and dried at 75°C for 9 hours to obtain a gas diffusion layer material;

[0058] (5) The gas diffusion layer material was immersed in a 34% mass fraction of 3,3'-diaminobenzidine N,N-dimethylacetamide solution, ultrasonically dispersed for 35 minutes, taken out and aired until no liquid droplets fell within 15 seconds, and allowed to stand at 145 ° C in a nitrogen atmosphere for 2 hours, heated to 195 ° C and allowed to stand for 15 hours, cooled naturally to room temperature, washed with deionized water 5 times, and dried at 85 ° C for 6 hours to obtain a pre-modified gas diffusion layer material; sodium sulfide, sodium carbonate and deionized water were mixed in a mass ratio of 1:0.9:45 to obtain a reaction solution; the pre-modified gas diffusion layer material was immersed in the reaction solution, allowed to stand at 105 ° C for 20 minutes, taken out, washed with deionized water 5 times, and dried at 75 ° C for 9 hours to obtain an amino gas diffusion layer material;

[0059] (6) Aniline and 1.1 mol / L hydrochloric acid solution were mixed at a mass ratio of 1:28 to obtain aniline hydrochloric acid solution; ammonium persulfate and 1.1 mol / L hydrochloric acid solution were mixed at a mass ratio of 1:12 to obtain ammonium persulfate hydrochloric acid solution; the amino-treated gas diffusion layer material was immersed in the aniline hydrochloric acid solution, ultrasonicated for 30 minutes, and an equal volume of ammonium persulfate hydrochloric acid solution was added, ultrasonicated for 30 minutes, taken out and aired until no liquid droplets fell within 15 seconds, allowed to stand at 1°C for 1 hour, washed with 1.1 mol / L hydrochloric acid solution and methanol respectively for 5 times, ultrasonicated in a 38% hydrochloric acid solution for 1 hour, washed with deionized water 5 times, and dried at 75°C for 8 hours to obtain a gas diffusion layer material for fuel cells.

[0060] Comparative Example 1:

[0061] The preparation method of the fuel cell gas diffusion layer material of Comparative Example 1 differs from that of Example 2 only in step (5), which is modified as follows: sodium sulfide, sodium carbonate, and deionized water are mixed in a mass ratio of 1:0.8:40 to obtain a reaction solution; the gas diffusion layer material is immersed in the reaction solution, allowed to stand at 100°C for 25 minutes, then taken out, washed four times with deionized water, and dried at 70°C for 10 hours to obtain an amino-treated gas diffusion layer material. The remaining steps are the same as those of Example 2.

[0062] Comparative Example 2:

[0063] The preparation method of the fuel cell gas diffusion layer material of Comparative Example 2 differs from that of Example 2 only in step (4). Step (4) is modified as follows: modified acetylene black, modified polytetrafluoroethylene, and anhydrous ethanol are mixed in a mass ratio of 1:0.25:4, ultrasonically dispersed for 30 minutes, stirred at 250 rpm for 30 minutes, and ultrasonically stirred for 5 times to obtain a microporous layer spray liquid; aluminum phosphate and anhydrous ethanol are mixed in a mass ratio of 1:15, ultrasonically dispersed to obtain a sealing liquid; the microporous layer spray liquid is sprayed onto a carboxylated carbon paper substrate heated on an electric hot plate with a spray gun to a thickness of 50 μm, and then transferred to a tube furnace, heated to 250°C at a rate of 5°C / min, baked for 30 minutes, further heated to 350°C at a rate of 2°C / min, sintered for 30 minutes, and then cooled to room temperature at a rate of 5°C / min before being taken out to obtain a gas diffusion layer material. The remaining steps are the same as those of Example 2.

[0064] Comparative Example 3:

[0065] The preparation method of the fuel cell gas diffusion layer material of Comparative Example 3 differs from that of Example 2 only in step (6). Step (6) is modified as follows: the amination gas diffusion layer material is immersed in a 37% by mass hydrochloric acid solution and ultrasonicated for 2 h. After removal, the amination gas diffusion layer material is washed four times with deionized water and dried at 70°C for 9 h to obtain the fuel cell gas diffusion layer material. The remaining steps are the same as those of Example 2.

[0066] Test Case

[0067] 1. Breathability

[0068] Test method: The gas diffusion layer materials for fuel cells obtained in each embodiment and comparative example were cut into samples with a size of 10 cm*10 cm, and the air permeability was tested using a Gurley 4320 air permeability measuring instrument.

[0069] 2. Conductivity

[0070] Test method: The gas diffusion layer materials for fuel cells obtained in each embodiment and comparative example were cut into samples of 8 cm*5 cm in size, and the in-plane resistivity was measured using a Mitsubishi MCP-T600 four-probe tester.

[0071] 3. Mechanical properties

[0072] Test method: The gas diffusion layer materials for fuel cells obtained in the examples and comparative examples were tested for tensile strength using a universal tensile testing machine at a tensile rate of 10 mm / min according to GB / T1040.

[0073] Table 1 below shows the analysis results of the electrical conductivity, air permeability and mechanical properties of the gas diffusion layer materials for fuel cells using Examples 1 to 3 of the present invention and Comparative Examples 1 to 3.

[0074] Table 1

[0075]

[0076] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 1, it can be found that the gas diffusion layer material for fuel cells prepared by the present invention has good electrical conductivity, air permeability and mechanical properties.

[0077] By comparison, Examples 1, 2, and 3 have higher in-plane resistivity and tensile strength than Comparative Example 1, indicating that 3,3'-diaminobenzidine condenses with the carboxylated carbon paper substrate to obtain a benzimidazole ring, and at the same time reacts with the acid anhydride on the surface of the modified acetylene black to form a stable π-electron conjugated structure, thereby constructing a dense and stable molecular chain between the carbon paper substrate and the acetylene black, thereby enhancing structural stability, promoting electron transfer, and enhancing the mechanical properties and conductivity of the gas diffusion layer material for fuel cells.

[0078] By comparison, the air permeabilities of Examples 1, 2, and 3 are higher than those of Comparative Example 2, indicating that the porosity of the high-porosity gas diffusion layer carbon paper is further improved by sealing the pores with aluminum phosphate and then dissolving the pores in concentrated hydrochloric acid to increase the pore structure.

[0079] By comparison, the in-plane resistivity and tensile strength of Examples 1, 2, and 3 are higher than those of Comparative Example 3, indicating that 3,4-epoxy-1-butene is grafted onto the surface of polytetrafluoroethylene through plasma activation, aniline is grafted using the epoxy ring-opening reaction, and conjugated long chains are formed through aniline oxidative polymerization. The aniline reaction active sites on the surface of the modified acetylene black are connected to form an interlaced cross-linked network, thereby improving the mechanical properties and conductivity of the gas diffusion layer material for fuel cells.

[0080] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A gas diffusion layer material for a fuel cell, characterized in that: The gas diffusion layer material for fuel cells is prepared by cross-linking the gas diffusion layer material with 3,3'-diaminobenzidine and then grafting polyaniline; The gas diffusion layer material is prepared by spraying modified acetylene black and modified polytetrafluoroethylene on a carboxylated carbon paper substrate after mixing, and then sintering and sealing the pores. The modified acetylene black is prepared by polymerizing maleic anhydride, styrene and 3-nitrostyrene and depositing them on the surface of acetylene black; The modified polytetrafluoroethylene is prepared by treating polytetrafluoroethylene powder and then grafting 3,4-epoxy-1-butene and aniline in sequence; The carboxylated carbon paper base layer is prepared by oxidation of the carbon paper base layer with nitric acid and sulfuric acid.

2. A method for preparing a gas diffusion layer material for a fuel cell, characterized in that: The method comprises the following preparation steps: (1) Immersing the carbon paper substrate in a mixed acid solution, taking it out after evaporation and reflux, washing and drying it to obtain an oxidized carbon paper substrate; Immersing the oxidized carbon paper substrate in a chloroacetic acid aqueous solution, adding sodium hydroxide, ultrasonically dispersing it, hanging it to stand, washing and drying it to obtain a carboxylated carbon paper substrate; (2) Mix acetylene black, maleic anhydride, styrene, 3-nitrostyrene, azobisisobutyronitrile and isoamyl acetate, disperse them by ultrasonication, cool to room temperature after the reaction, centrifuge, wash and dry to obtain modified acetylene black; (3) Pre-treated polytetrafluoroethylene, 3,4-epoxy-1-butene, benzoyl peroxide and chlorobenzene are mixed, cooled to room temperature after reaction, centrifuged, washed and dried to obtain pre-modified polytetrafluoroethylene; the pre-modified polytetrafluoroethylene is immersed in aniline ethanol solution, ultrasonicated, hung and allowed to stand, washed and dried to obtain modified polytetrafluoroethylene; (4) Mixing modified acetylene black, modified polytetrafluoroethylene and anhydrous ethanol, and repeatedly ultrasonically stirring to obtain a microporous layer spraying liquid; The microporous layer spraying liquid is sprayed on the carboxylated carbon paper substrate heated by an electric hot plate using a spray gun, and then placed in a tube furnace for baking and sintering. After cooling to room temperature, the gas diffusion layer material is taken out. (5) Immersing the gas diffusion layer material in a solution of 3,3'-diaminobenzidine in N,N-dimethylacetamide, ultrasonically dispersing it, hanging it to stand, cooling it to room temperature, washing and drying it to obtain a pre-modified gas diffusion layer material; immersing the pre-modified gas diffusion layer material in a reaction solution obtained by mixing sodium sulfide, sodium carbonate and deionized water in a mass ratio of 1:(0.7~0.9):(35~45), standing it, taking it out, washing and drying it to obtain an amino-modified gas diffusion layer material; (6) Immersing the amino-treated gas diffusion layer material in an aniline hydrochloric acid solution, ultrasonicating it, adding an ammonium persulfate hydrochloric acid solution, ultrasonicating it, hanging it to stand, washing it, ultrasonicating it with concentrated hydrochloric acid, and then washing and drying it to obtain a gas diffusion layer material for a fuel cell.

3. The method for preparing a gas diffusion layer material for a fuel cell according to claim 2, characterized in that: The specific preparation process of the carboxylated carbon paper substrate in step (1) is as follows: nitric acid and sulfuric acid are mixed in a volume ratio of 1:(2~4) to obtain a mixed acid solution; the carbon paper substrate is immersed in the mixed acid solution, evaporated and refluxed at 75~85°C for 11~13h, washed with deionized water and anhydrous ethanol for 3~5 times respectively, and dried at 60~70°C for 9~11h to obtain an oxidized carbon paper substrate; the oxidized carbon paper substrate is immersed in a chloroacetic acid aqueous solution with a mass fraction of 1%~3%, sodium hydroxide with a molar amount of 0.4~0.5 times that of chloroacetic acid in the chloroacetic acid aqueous solution is added, ultrasonically dispersed for 25~35min, taken out and aired until no liquid drops within 5~15s, allowed to stand at 30~40°C for 5~7h, washed with a hydrochloric acid solution with a mass fraction of 36%~38% and deionized water for 3~5 times respectively, and dried at 60~70°C for 11~13h to obtain a carboxylated carbon paper substrate.

4. The method for preparing a gas diffusion layer material for a fuel cell according to claim 2, wherein: The specific preparation process of the modified acetylene black in step (2) is as follows: acetylene black, maleic anhydride, styrene, 3-nitrostyrene, azobisisobutyronitrile and isoamyl acetate are mixed in a mass ratio of 1:(1~3):(0.9~1.1):(0.6~0.7):(0.03~0.04):(14~16), ultrasonically dispersed for 20~30min, stirred for 7~9h at 70~80℃ and 200~400rpm in a nitrogen atmosphere, cooled naturally to room temperature and then centrifuged, washed with isoamyl acetate and petroleum ether for 3~5 times respectively, and dried at 50~60℃ for 11~13h to obtain modified acetylene black.

5. The method for preparing a gas diffusion layer material for a fuel cell according to claim 2, characterized in that: The specific preparation process of the modified polytetrafluoroethylene in step (3) is as follows: polytetrafluoroethylene powder is treated in an argon atmosphere at a voltage of 35~45V for 200~400s, and allowed to stand for 5~15min to obtain pre-treated polytetrafluoroethylene; pre-treated polytetrafluoroethylene, 3,4-epoxy-1-butene, benzoyl peroxide and chlorobenzene are mixed in a mass ratio of 1:(1.3~1.5):(0.06~0.08):(3~5), and stirred in a nitrogen atmosphere at 85~95℃ and 300~400rpm for 4~6 h, naturally cooled to room temperature and then centrifuged, washed with acetone and deionized water for 3 to 5 times respectively, and dried at 55 to 65°C for 23 to 25 hours to obtain pre-modified polytetrafluoroethylene; the pre-modified polytetrafluoroethylene was immersed in an aniline ethanol solution with a volume fraction of 55% to 65%, ultrasonicated for 20 to 30 minutes, taken out and aired until no liquid drops within 5 to 15 seconds, allowed to stand at 55 to 65°C in a nitrogen atmosphere for 5 to 7 hours, washed with deionized water for 3 to 5 times, and dried at 65 to 75°C for 8 to 10 hours to obtain modified polytetrafluoroethylene.

6. The method for preparing a gas diffusion layer material for a fuel cell according to claim 2, characterized in that: The specific preparation process of the gas diffusion layer material in step (4) is as follows: modifying acetylene black, modifying polytetrafluoroethylene and anhydrous ethanol in a mass ratio of 1: (0.2-0.3): (3-5) are mixed, ultrasonically dispersed for 25-35 minutes, stirred at 200-300 rpm for 25-35 minutes, and ultrasonically stirred for 4-6 times to obtain a microporous layer spraying liquid; aluminum phosphate and anhydrous ethanol in a mass ratio of 1: (14-16) are mixed, ultrasonically dispersed to obtain a sealing liquid; the microporous layer spraying liquid is sprayed on the carboxyl group heated by the electric heating plate with a spray gun. The carbon paper substrate is sprayed to a thickness of 40~60μm, moved into a tube furnace, heated to 240~260℃ at a rate of 4~6℃ / min, baked for 25~35min, continued to heat to 340~360℃ at a rate of 1~3℃ / min, sintered for 25~35min, and then cooled to room temperature at a rate of 4~6℃ / min, taken out, ultrasonicated in the sealing liquid for 20~30min, taken out, washed with deionized water 3~5 times, and dried at 65~75℃ for 9~11h to obtain a gas diffusion layer material.

7. The method for preparing a gas diffusion layer material for a fuel cell according to claim 2, characterized in that: The specific preparation process of the amino gas diffusion layer material in step (5) is as follows: immerse the gas diffusion layer material in a 32% to 34% by mass 3,3'-diaminobenzidine N,N-dimethylacetamide solution, ultrasonically disperse for 25 to 35 minutes, take it out and air it until no liquid drops fall within 5 to 15 seconds, stand it at 135 to 145 ° C in a nitrogen atmosphere for 2 to 4 hours, heat it to 185 to 195 ° C and stand it for 15 to 20 hours, cool it naturally to room temperature, and use deionized water. The pre-modified gas diffusion layer material is washed with water for 3 to 5 times and dried at 75 to 85° C. for 6 to 8 hours to obtain a pre-modified gas diffusion layer material; sodium sulfide, sodium carbonate and deionized water are mixed at a mass ratio of 1:(0.7 to 0.9):(35 to 45) to obtain a reaction solution; the pre-modified gas diffusion layer material is immersed in the reaction solution, allowed to stand at 95 to 105° C. for 20 to 30 minutes, and then taken out, washed with deionized water for 3 to 5 times, and dried at 65 to 75° C. for 9 to 11 hours to obtain an amino gas diffusion layer material.

8. The method for preparing a gas diffusion layer material for a fuel cell according to claim 2, characterized in that: The specific preparation process of the gas diffusion layer material for fuel cells in step (6) is as follows: aniline and 0.9-1.1 mol / L hydrochloric acid solution are mixed at a mass ratio of 1:(26-28) to obtain an aniline hydrochloric acid solution; ammonium persulfate and 0.9-1.1 mol / L hydrochloric acid solution are mixed at a mass ratio of 1:(10-12) to obtain an ammonium persulfate hydrochloric acid solution; The aminated gas diffusion layer material is immersed in an aniline hydrochloric acid solution, ultrasonicated for 20-30 minutes, and an ammonium persulfate hydrochloric acid solution of equal volume to the aniline hydrochloric acid solution is added, ultrasonicated for 20-30 minutes, taken out and aired until no liquid drops within 5-15 seconds, and allowed to stand at -1-1°C for 1-3 hours, and washed with 0.9-1.1 mol / L hydrochloric acid solution and methanol for 3-5 times respectively, and ultrasonicated in a hydrochloric acid solution with a mass fraction of 36%-38% for 1-3 hours, washed with deionized water for 3-5 times, and dried at 65-75°C for 8-10 hours to obtain a gas diffusion layer material for a fuel cell.

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