CN114094124A - Gas diffusion layer and preparation method and application thereof - Google Patents
Gas diffusion layer and preparation method and application thereof Download PDFInfo
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- CN114094124A CN114094124A CN202111375669.5A CN202111375669A CN114094124A CN 114094124 A CN114094124 A CN 114094124A CN 202111375669 A CN202111375669 A CN 202111375669A CN 114094124 A CN114094124 A CN 114094124A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/94—Non-porous diffusion electrodes, e.g. palladium membranes, ion exchange membranes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/88—Processes of manufacture
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Abstract
The invention provides a gas diffusion layer and a preparation method and application thereof, wherein the preparation method comprises the following steps: coating the microporous layer slurry on a hydrophobic substrate to obtain the gas diffusion layer; the microporous layer slurry is obtained by mixing conductive carbon and a sulfonic hydrocarbon auxiliary agent. In order to improve the gas permeability of the gas diffusion layer and improve the physical and chemical properties of the gas diffusion layer, the invention adopts the sulfonic hydrocarbon auxiliary agent to establish an energy barrier in the microporous layer of the gas diffusion layer and reduce the agglomeration among particles in slurry of the microporous layer, thereby improving the porosity of the gas diffusion layer and reducing the resistance; therefore, after the sulfonic hydrocarbon assistant is added into the microporous layer of the gas diffusion layer, the dispersibility of slurry of the microporous layer is improved, the particle size in the slurry is obviously reduced, the resistivity, the porosity and the air permeability of the gas diffusion layer are also obviously improved, and the obtained gas diffusion layer can meet the power requirement of a battery under high current density.
Description
Technical Field
The invention belongs to the field of proton exchange membrane fuel cells, relates to a diffusion layer, and particularly relates to a gas diffusion layer and a preparation method and application thereof.
Background
The proton exchange membrane fuel cell has the characteristics of low working temperature, quick start, high power density, mature application and the like, and is widely applied, particularly in the automobile industry. However, the service life of the current fuel cell cannot meet the increasingly high requirements of the current market, so that the service life is prolonged to be one of the most important problems for popularization and application of the fuel cell.
The membrane electrode in the proton exchange membrane fuel cell is a core component, and the gas diffusion layer is positioned between the flow field and the catalyst layer, and is used for supporting the catalyst layer, stabilizing the electrode structure, transferring protons, electrons, heat and transporting reaction gas, and quickly discharging water generated in the process. The gas diffusion layer is generally composed of a support layer and a microporous layer, wherein most of the support layer is hydrophobic porous carbon paper or carbon cloth, and the microporous layer is generally composed of conductive carbon black and a hydrophobic agent, so that the contact resistance between the catalyst layer and the support layer is reduced, reaction gas and product water are uniformly distributed between the flow field and the catalyst layer, and the performance of the electrode is improved. With the increasing power density of fuel cells, the mass transfer function of the gas diffusion layer under high current density has also drawn attention gradually. Under the condition of large electric density, a large amount of water can be generated, if the water is not discharged in time, particularly under the working condition of low-temperature cold start, mass transfer polarization can be greatly increased, the performance of the battery is poor, and the service life of the battery is seriously influenced. Therefore, under high current density, the water-gas unobstructed mass transfer technology and the improvement of the battery life are the difficult problems faced by the gas diffusion layer.
CN 109301258A discloses a fuel cell gas diffusion layer and a preparation method thereof, wherein, one surface of carbon paper is coated with gas diffusion layer slurry which comprises PTFE, carbon powder and porous nano-fiber nickel powder and then is sintered; the porosity and the conductivity of the gas diffusion layer of the fuel cell and the service life are improved by adding the porous nano-fibrous nickel powder into the slurry and controlling the mass ratio of the carbon powder to the porous nano-fibrous nickel powder.
CN 112952114a discloses a gas diffusion layer, a preparation method and an application thereof, the gas diffusion layer comprises a first microporous layer, a second microporous layer and a substrate layer which are sequentially attached; the first microporous layer and the second microporous layer both comprise carbon powder, polytetrafluoroethylene and SiO2Reduced graphene oxide composites; by adding SiO to the microporous layer2The reduced graphene oxide composite material is characterized in that a double-layer microporous layer is designed, and a fuel cell gas diffusion layer with gradient change of hydrophobicity is constructed, so that the hydrophobic property of the diffusion layer under high current density is improved.
The above prior arts are all based on the introduction of additives into the gas diffusion layer to improve the porosity, hydrophobicity, conductivity and other problems of the gas diffusion layer. However, in the above preparation method, there is no description about the stability and the stabilization time of the slurry, and the conventional microporous layer slurry can only be maintained for several hours, which is not enough to maintain the subsequent coating process, and the microporous layer slurry is agglomerated, which affects the coating quality, thereby causing the overall performance of the battery to be significantly reduced.
Based on the research, how to provide a gas diffusion layer, the dispersibility of the slurry of the microporous layer in the gas diffusion layer is good, the particles in the slurry are not easy to agglomerate, and the microporous layer can obviously improve the gas permeability and the water removal in the gas diffusion layer and reduce the resistance of the gas diffusion layer, so that the ohmic polarization and the concentration polarization of the battery can be reduced, the requirement of the power of the battery under the high current density is improved, and the problem which needs to be solved urgently at present is solved.
Disclosure of Invention
The invention aims to provide a gas diffusion layer and a preparation method and application thereof, wherein the gas diffusion layer comprises a hydrophobic substrate and a microporous layer, the microporous layer can remarkably improve the permeability of gas and the discharge of water in the gas diffusion layer, and reduce the resistance of the gas diffusion layer, thereby being beneficial to reducing the ohmic polarization and concentration polarization of a battery and improving the requirement of the battery on power under high current density, and the microporous layer has good slurry dispersibility, is not easy to agglomerate and has long stabilization time.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for preparing a gas diffusion layer, the method comprising the steps of:
coating the microporous layer slurry on a hydrophobic substrate to obtain the gas diffusion layer;
the microporous layer slurry is obtained by mixing conductive carbon and a sulfonic hydrocarbon auxiliary agent;
the sulfonic hydrocarbon assistant comprises any one or combination of at least two of succinic acid bis-2-ethylhexyl ester sodium sulfonate, dibutyl benzene sodium sulfonate, sodium lignin sulfonate, condensed naphthalene sodium sulfonate or polystyrene sodium sulfonate, and typical but non-limiting combinations comprise the combination of succinic acid bis-2-ethylhexyl ester sodium sulfonate and dibutyl benzene sodium sulfonate, the combination of succinic acid bis-2-ethylhexyl ester sodium sulfonate and sodium lignin sulfonate, the combination of dibutyl benzene sodium sulfonate and condensed naphthalene sodium sulfonate, or the combination of succinic acid bis-2-ethylhexyl ester sodium sulfonate and condensed naphthalene sodium sulfonate.
The invention adopts sulfonic acid group hydrocarbon auxiliary agent, the sulfonic acid group of which is taken as a polar end, and forms strong physical adsorption and chemical adsorption with the surface of conductive carbon, wherein the physical adsorption utilizes coulomb force adsorption, and the chemical adsorption is that oxygen in the sulfonic acid group and active groups on the surface of the conductive carbon are chemically adsorbed to generate C-O-SO2-R "such that the sulfonic hydrocarbon adjuvant is coated on the surface of the conductive carbon particles to resist the attractive forces between the conductive carbon particles and to create an energy barrier to reduce interparticle agglomeration in the microporous layer slurry; meanwhile, after the dosage of the sulfonic hydrocarbon auxiliary agent reaches saturation to form adsorption, a space barrier is provided to form a steric hindrance effect, so that the agglomeration among particles is reduced; the sulfonic acid group hydrocarbon additive can be discharged through high-temperature drying decomposition after the microporous layer slurry is coated.
Preferably, the sulfonic acid-based hydrocarbon additive comprises 0.05 to 5 wt% of the microporous layer slurry, and may be, for example, 0.05 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%, but is not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the microporous layer slurry has a solids content of 2 to 5 wt%, such as 2 wt%, 3 wt%, 4 wt%, or 5 wt%, but not limited to the recited values, and other values not recited within the range of values are equally applicable.
Preferably, the microporous layer slurry has a pH of 5 to 8, such as 5, 6, 7, or 8, but not limited to the recited values, and other values within the range are equally applicable.
Preferably, the conductive carbon comprises any one of or a combination of at least two of conductive carbon black, carbon fibers, carbon nanotubes, or graphene materials, with typical but non-limiting combinations including combinations of conductive carbon black and carbon fibers, combinations of conductive carbon black and carbon nanotubes, or combinations of carbon nanotubes and graphene materials.
The conductive carbon black includes any one of or a combination of at least two of ketjen black, acetylene black, BP2000 carbon black, Vulcan P carbon black, Printex L carbon black, Super P carbon black, or Super S carbon black, and typical, but not limiting, combinations include a combination of ketjen black and acetylene black, a combination of acetylene black and BP2000 carbon black, or a combination of ketjen black and BP2000 carbon black.
The carbon nanotubes comprise single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
The graphene material comprises any one of graphene, graphene oxide, hydrogenated graphene, or fluorinated graphene, or a combination of at least two of them, typical but non-limiting combinations include a combination of graphene and graphene oxide, a combination of graphene and hydrogenated graphene, or a combination of graphene oxide and hydrogenated graphene.
Preferably, the carbon loading of the conductive carbon in the microporous layer slurry is 0.7-5 mg/cm2For example, it may be 0.7mg/cm2、1mg/cm2、2mg/cm2、3mg/cm2、4mg/cm2Or 5mg/cm2But, however, doNot limited to the recited values, other values not recited within the numerical range are equally applicable.
Preferably, the microporous layer slurry further comprises a water repellent, a pore-forming agent and a solvent.
Preferably, the water repellent comprises any one of or a combination of at least two of polytetrafluoroethylene, fluorinated ethylene propylene copolymer, polyvinylidene fluoride emulsion or polyhexafluoropropylene emulsion, typical but non-limiting combinations include a combination of polytetrafluoroethylene and fluorinated ethylene propylene copolymer, a combination of polytetrafluoroethylene and polyvinylidene fluoride emulsion, or a combination of fluorinated ethylene propylene copolymer and polyvinylidene fluoride emulsion.
Preferably, the pore-forming agent comprises PEG (polyethylene glycol) -200, PEG-400, ammonium oxalate, lithium carbonate, ammonium chloride, (NH)4)2CO3、(NH4)HCO3Any one of glucose, L-arabinose or ethyl acetate or a combination of at least two thereof, typical but non-limiting combinations include a combination of glucose and lithium carbonate, a combination of ammonium chloride and L-arabinose, or a combination of L-arabinose and ethyl acetate.
Preferably, the solvent comprises any one or a combination of at least two of deionized water, ethylene glycol, N-propanol, ethanol, or NMP (N-methylpyrrolidone), and typical but non-limiting combinations include a combination of deionized water and ethylene glycol, a combination of deionized water and N-propanol, or a combination of ethylene glycol and N-propanol.
Preferably, the mass ratio of the water repellent to the conductive carbon is 1 (1-3), for example, 1:1, 1:2 or 1:3, but not limited to the values listed, and other values not listed in the range of values are also applicable.
The mass ratio of the pore-forming agent to the conductive carbon is preferably 1 (1-3), and may be, for example, 1:1, 1:2 or 1:3, but is not limited to the values listed, and other values not listed in the range of values are also applicable.
Preferably, the microporous layer slurry is obtained by the following method:
(1) mixing the conductive carbon and the water repellent emulsion for 5-10 min to obtain a first mixed solution;
(2) mixing a solvent with the first mixed solution obtained in the step (1) for 20-30 min to obtain a second mixed solution;
(3) mixing the pore-forming agent solution with the second mixed solution obtained in the step (2) for 5-10 min to obtain a third mixed solution;
(4) and (4) mixing the sulfonic hydrocarbon assistant with the third mixed solution obtained in the step (3) for 10-15 min, and then carrying out ultrasonic treatment for 1-2 h to obtain the microporous layer slurry.
When the microporous layer slurry is prepared, the conductive carbon is fully contacted with the water repellent by adopting step-by-step high-speed stirring, the particle size is changed into a nanometer level by the shearing force during the high-speed stirring, and the stirring temperature of the slurry is reduced by matching with external cooling, so that the intermolecular motion in the slurry is reduced, and the agglomeration among particles is reduced, therefore, the microporous layer slurry has good stability, is not easy to settle and has good consistency.
Preferably, the manner of mixing includes any one or a combination of at least two of paddle stirring, magnetic stirring or shear stirring, and typical but non-limiting combinations include a combination of paddle stirring and magnetic stirring, a combination of paddle stirring and shear stirring, or a combination of magnetic stirring and shear stirring.
Preferably, the rotation speed of the mixing is 5000-25000 rpm, and the temperature is-5-15 ℃.
The mixing speed is 5000-25000 rpm, for example 5000rpm, 10000rpm, 20000rpm or 25000rpm, but is not limited to the values listed, and other values not listed in the range of the values are also applicable.
The mixing temperature is-5 to 15 ℃, for example, -5 ℃, 0 ℃, 5 ℃, 10 ℃ or 15 ℃, but not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, in the water repellent emulsion in the step (1), the mass percentage of the water repellent is 10 to 65 wt%, for example, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt% or 65 wt%, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
In the water repellent emulsion in the step (1), the water repellent comprises any one of or a combination of at least two of polytetrafluoroethylene, fluorinated ethylene propylene copolymer, polyvinylidene fluoride emulsion or polyhexafluoropropylene emulsion, and typical but non-limiting combinations comprise a combination of polytetrafluoroethylene and fluorinated ethylene propylene copolymer, a combination of polytetrafluoroethylene and polyvinylidene fluoride emulsion or a combination of fluorinated ethylene propylene copolymer and polyvinylidene fluoride emulsion.
Preferably, in the pore-forming agent solution in the step (3), the mass percentage of the pore-forming agent is 10 to 70 wt%, for example, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, or 70 wt%, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
In the pore-forming agent solution in the step (3), the pore-forming agent comprises PEG (polyethylene glycol) -200, PEG-400, ammonium oxalate, lithium carbonate, ammonium chloride, (NH)4)2CO3、(NH4)HCO3Any one of glucose, L-arabinose or ethyl acetate or a combination of at least two thereof, typical but non-limiting combinations include a combination of glucose and lithium carbonate, a combination of ammonium chloride and L-arabinose, or a combination of L-arabinose and ethyl acetate.
Preferably, the frequency of the ultrasound in the step (4) is 20 to 50kHz, such as 20kHz, 30kHz, 40kHz or 50kHz, but not limited to the enumerated values, and other unrecited values in the numerical range are also applicable.
Preferably, the hydrophobic substrate comprises any one of carbon paper, carbon felt, carbon fiber paper, carbon fiber woven cloth, mesh titanium substrate, mesh nickel substrate or mesh copper substrate or a combination of at least two of them, and typical but non-limiting combinations include a combination of carbon paper and carbon felt, a combination of carbon felt and carbon fiber woven cloth, or a combination of carbon fiber paper and carbon fiber woven cloth.
Preferably, the hydrophobic substrate is pretreated before use, and the pretreatment method comprises the following steps: and (3) soaking the hydrophobic substrate in 10-20 wt% of water repellent emulsion, and drying to obtain the pretreated hydrophobic substrate.
The mass percentage of the hydrophobic agent emulsion impregnated on the hydrophobic substrate is 10-20 wt%, for example 10 wt%, 15 wt% or 20 wt%, but is not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the dipping times are 2-8 times, and the temperature is 30-40 ℃.
The number of the dipping is 2 to 8, and may be, for example, 2, 3, 4, 5, 6, 7 or 8.
The temperature of the impregnation is 30 to 40 ℃, for example, 30 ℃, 35 ℃ or 40 ℃, but not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the time for a single immersion is 10-20 min, such as 10min, 15min or 20min, but not limited to the recited values, and other values not recited in the range of values are also applicable.
And replacing the fresh water repellent emulsion after the single impregnation is finished.
Preferably, the drying temperature is 250-450 ℃, and the drying time is 1-2 h.
The drying temperature is 250-450 ℃, for example, 250 ℃, 350 ℃ or 450 ℃, but not limited to the recited values, and other values in the range of the values not recited are also applicable.
The drying time is 1 to 2 hours, for example, 1 hour, 1.5 hours or 2 hours, but the drying time is not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the drying apparatus comprises an oven and/or a muffle.
Preferably, the thickness of the hydrophobic substrate after pretreatment is 130-150 μm, the content of the water repellent is 3-10 wt%, and the porosity is 60-70%.
The thickness of the hydrophobic substrate after pretreatment is 130-150 μm, for example 130 μm, 140 μm or 150 μm, but is not limited to the values listed, and other values not listed in the range of the values are also applicable.
The hydrophobic agent content of the hydrophobic substrate is 3 to 10 wt%, for example, 3 wt%, 5 wt% or 10 wt%, but not limited to the recited values, and other values not recited within the range of values are also applicable.
The hydrophobic substrate has a porosity of 60 to 70%, for example 60%, 65% or 70%, but is not limited to the recited values, and other values not recited in the numerical ranges are equally applicable.
Preferably, the coating method comprises any one or a combination of at least two of screen printing, spray coating, hand painting, slot extrusion or roll printing, and typical but non-limiting combinations include a combination of screen printing and spray coating, a combination of spray coating and hand painting, or a combination of screen printing and hand painting.
Preferably, the coating is a single-sided coating.
Preferably, the coating environment is a vacuum environment, the temperature is 100-120 ℃, for example, 100 ℃, 110 ℃ or 120 ℃, but not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the coating has a thickness of 10 to 60 μm, for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm or 60 μm, but is not limited to the values listed, and other values not listed in the numerical range are also applicable.
Preferably, the coating also comprises sintering and hot pressing which are sequentially carried out.
Preferably, the sintering temperature is 300-400 ℃, and the time is 1-2 h.
The sintering temperature is 300-400 ℃, for example, 300 ℃, 350 ℃ or 400 ℃, but not limited to the recited values, and other values not recited in the numerical range are also applicable.
The sintering time is 1-2 h, for example, 1h, 1.5h or 2h, but is not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the sintering equipment comprises any one of an oven, a box-type resistance furnace, a muffle furnace or an infrared heater or a combination of at least two of them, and typical but non-limiting combinations include a combination of an oven and a muffle furnace or a combination of an oven and an infrared heater.
Preferably, the temperature of the hot-pressing treatment is 200-300 ℃, and the pressure is 5-10 kg/cm2The time is 10 to 20 seconds.
The temperature of the hot pressing treatment is 200 to 300 ℃, for example, 200 ℃, 250 ℃ or 300 ℃, but not limited to the recited values, and other values not recited in the numerical range are also applicable.
The pressure of the hot pressing treatment is 5-10 kg/cm2For example, it may be 5kg/cm2、8kg/cm2Or 10kg/cm2But are not limited to the recited values, and other values within the numerical range not recited are equally applicable.
The time of the hot pressing is 10 to 20 seconds, for example, 10 seconds, 15 seconds or 20 seconds, but the hot pressing is not limited to the recited values, and other values not recited in the range of the values are also applicable.
As a preferable technical solution of the method for preparing a gas diffusion layer of the present invention, the method comprises the steps of:
(1) stirring and mixing the conductive carbon and the water repellent emulsion at the temperature of-5-15 ℃ and the rotating speed of 5000-25000 rpm for 5-10 min to obtain a first mixed solution;
in the water repellent emulsion, the mass percent of the water repellent is 10-65 wt%, and the mass ratio of the water repellent to the conductive carbon is 1 (1-3);
(2) stirring and mixing a solvent and the first mixed solution obtained in the step (1) at a temperature of-5-15 ℃ and a rotating speed of 5000-25000 rpm for 20-30 min to obtain a second mixed solution;
(3) stirring and mixing the pore-forming agent solution and the second mixed solution obtained in the step (2) at the temperature of-5-15 ℃ and the rotating speed of 5000-25000 rpm for 5-10 min to obtain a third mixed solution;
in the pore-forming agent solution, the mass percent of the pore-forming agent is 10-70 wt%, and the mass ratio of the pore-forming agent to the conductive carbon is 1 (1-3);
(4) stirring and mixing the sulfonic hydrocarbon auxiliary agent and the third mixed solution obtained in the step (3) at a temperature of-5-15 ℃ at a rotating speed of 5000-25000 rpm for 10-15 min, and then carrying out ultrasonic treatment at a frequency of 20-50 kHz for 1-2 h to obtain microporous layer slurry with a solid content of 2-5% and a pH value of 5-8;
the sulfonic hydrocarbon auxiliary agent accounts for 0.05-5 wt% of the microporous layer slurry; in the microporous layer slurry, the carbon loading of the conductive carbon is 0.7-5 mg/cm2；
(5) Coating microporous layer slurry with the thickness of 10-60 mu m on one side of a hydrophobic substrate at the temperature of 100-120 ℃ in a vacuum environment, sintering the obtained composite hydrophobic substrate for 1-2 hours at the temperature of 300-400 ℃, and then sintering at the temperature of 200-300 ℃ and the temperature of 5-10 kg/cm2Carrying out hot pressing for 10-20 s under the pressure to obtain the gas diffusion layer;
the hydrophobic substrate is pretreated, and the pretreatment method comprises the following steps: dipping a hydrophobic substrate in 10-20 wt% of water repellent emulsion for 2-8 times at the temperature of 30-40 ℃, and then drying for 1-2 h at the temperature of 250-450 ℃ to finish pretreatment; the time of single dipping is 10-20 min; the thickness of the hydrophobic substrate after pretreatment is 130-150 mu m, the content of the water repellent is 3-10 wt%, and the porosity is 60-70%.
The preparation method is carried out in a dust-free environment.
In a second aspect, the present invention provides a gas diffusion layer obtained by the method of the first aspect, the gas diffusion layer comprising a hydrophobic substrate and a microporous layer.
In a third aspect, the present invention is directed to a fuel cell comprising a gas diffusion layer as described in the second aspect.
Compared with the prior art, the invention has the following beneficial effects:
the invention adopts sulfonic acid group hydrocarbon auxiliary agent, the sulfonic acid group of which is taken as a polar end, and forms strong physical adsorption and chemical adsorption with the surface of conductive carbon, wherein the physical adsorption utilizes coulomb force adsorption, and the chemical adsorption is that oxygen in the sulfonic acid group and active groups on the surface of the conductive carbon are chemically adsorbed to generate C-O-SO2-R "so that the sulfonic acid-based hydrocarbon assistant can be coated on the surface of the conductive carbon particles to resist the attractive force between the conductive carbon particles and establish an energy barrier to reduce microporesAgglomeration between particles in the layer slurry; meanwhile, after the dosage of the sulfonic hydrocarbon auxiliary agent reaches saturation to form adsorption, a space barrier is provided to form a steric hindrance effect, so that the agglomeration among particles is reduced; the sulfonic hydrocarbon additive can be discharged by high-temperature drying decomposition after being coated on the microporous layer slurry; the microporous layer can obviously improve the permeability of gas and the removal of water in the gas diffusion layer and reduce the resistance of the gas diffusion layer, thereby being beneficial to reducing the ohmic polarization and the concentration polarization of the battery and improving the power requirement of the battery under high current density.
Drawings
Fig. 1 is a schematic view of the structure of a gas diffusion layer according to the present invention.
FIG. 2 is a molecular structural diagram of sodium bis-2-ethylhexyl sulfosuccinate according to the present invention.
FIG. 3 is a schematic view of the adsorption structure of the sulfonated hydrocarbon assistant according to the present invention with conductive carbon.
Wherein, 1-hydrophobic substrate, 2-microporous layer, 3-sulfonic acid group hydrocarbon auxiliary agent and 4-conductive carbon.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
This example provides a method of preparing a gas diffusion layer as shown in fig. 1, the gas diffusion layer comprising a hydrophobic substrate 1 and a microporous layer 2, the hydrophobic substrate 1 comprising carbon paper;
the preparation method of the gas diffusion layer comprises the following steps:
(1) shearing, stirring and mixing Keqin black and a polytetrafluoroethylene solution at the temperature of 5 ℃ and the rotating speed of 5000rpm for 5min to obtain a first mixed solution;
in the polytetrafluoroethylene solution, the mass percent of polytetrafluoroethylene is 10 wt%, and the mass ratio of ketjen black to polytetrafluoroethylene is 1: 1;
(2) shearing, stirring and mixing deionized water and the first mixed solution obtained in the step (1) at the temperature of 5 ℃ and the rotating speed of 5000rpm for 20min to obtain a second mixed solution;
(3) shearing, stirring and mixing the PEG-200 solution and the second mixed solution obtained in the step (2) at the temperature of 5 ℃ and the rotating speed of 10000rpm for 10min to obtain a third mixed solution;
in the PEG-200 solution, the mass percent of the PEG-200 is 10 wt%, and the mass ratio of the PEG-200 to the Ketjen black is 1: 1;
(4) shearing, stirring and mixing the succinic acid bis-2-ethylhexyl ester sodium sulfonate and the third mixed solution obtained in the step (3) at the temperature of 5 ℃ and the rotating speed of 5000rpm for 15min, and then carrying out ultrasonic treatment for 1h at the frequency of 20kHz to obtain microporous layer slurry with the solid content of 2% and the pH value of 8;
the sodium bis-2-ethylhexyl sulfosuccinate comprises 0.05 wt% of the microporous layer slurry; the carbon loading of Ketjen black in the microporous layer slurry was 0.7mg/cm2；
(5) Soaking carbon paper in 10 wt% of polytetrafluoroethylene solution at the temperature of 30 ℃, and drying in an oven at the temperature of 250 ℃ for 2h to obtain pretreated carbon paper;
the time of single impregnation is 10min, and after the single impregnation is finished, the fresh polytetrafluoroethylene solution is replaced, and the impregnation times are 2 times; the thickness of the pretreated carbon paper is 130 mu m, the content of polytetrafluoroethylene is 3 wt%, and the porosity is 60%;
(6) coating the slurry of the microporous layer in the step (4) on the pretreated carbon paper in the step (5) in a slit extrusion mode at the temperature of 100 ℃ in a vacuum environment to obtain composite carbon paper, sintering the composite carbon paper for 2 hours at the temperature of 300 ℃ in an argon environment, and sintering the composite carbon paper at the temperature of 200 ℃ in the range of 10kg/cm2Hot pressing for 10s under the pressure of the gas diffusion layer to obtain the gas diffusion layer;
the thickness of the single-side coating is 10 mu m;
the molecular structure diagram of the succinic acid bis-2-ethylhexyl ester sodium sulfonate is shown in figure 2, and the adsorption structure diagram of the sulfonic acid group hydrocarbon auxiliary agent 3 and the conductive carbon 4 is shown in figure 3.
Example 2
The present embodiment provides a method for preparing a gas diffusion layer, the gas diffusion layer comprising a hydrophobic substrate 1 and a microporous layer 2, the hydrophobic substrate 1 comprising carbon paper;
the preparation method of the gas diffusion layer comprises the following steps:
(1) shearing, stirring and mixing a single-walled carbon nanotube and a polytetrafluoroethylene solution at the temperature of 15 ℃ at the rotating speed of 25000rpm for 10min to obtain a first mixed solution;
in the polytetrafluoroethylene solution, the mass percent of polytetrafluoroethylene is 65 wt%, and the mass ratio of polytetrafluoroethylene to single-walled carbon nanotubes is 1: 3;
(2) shearing, stirring and mixing ethylene glycol and the first mixed solution obtained in the step (1) at the temperature of 15 ℃ and the rotating speed of 25000rpm for 30min to obtain a second mixed solution;
(3) shearing, stirring and mixing the ammonium oxalate solution and the second mixed solution obtained in the step (2) at the temperature of 15 ℃ and the rotating speed of 5000rpm for 10min to obtain a third mixed solution;
in the ammonium oxalate solution, the mass percent of ammonium oxalate is 70 wt%, and the mass ratio of ammonium oxalate to single-walled carbon nanotubes is 1: 2.3;
(4) shearing, stirring and mixing the succinic acid bis-2-ethylhexyl ester sodium sulfonate and the third mixed solution obtained in the step (3) at the temperature of 15 ℃ and at the rotating speed of 25000rpm for 15min, and then carrying out ultrasonic treatment at the frequency of 50kHz for 2h to obtain microporous layer slurry with the solid content of 5% and the pH value of 5;
the sodium bis-2-ethylhexyl sulfosuccinate comprises 2.5 wt% of the microporous layer slurry; the carbon loading of the single-walled carbon nanotube in the microporous layer slurry is 2.5mg/cm2；
(5) Dipping carbon paper in 20 wt% polyvinylidene fluoride emulsion at 40 ℃, and drying in an oven at 450 ℃ for 1h to obtain pretreated carbon paper;
the time of single impregnation is 20min, and after the single impregnation is finished, the fresh polyvinylidene fluoride emulsion is replaced, and the impregnation times are 8; the thickness of the pretreated carbon paper is 150 mu m, the content of polyvinylidene fluoride emulsion is 10 wt%, and the porosity is 70%;
(6) coating the microporous layer slurry obtained in the step (4) on the pretreated carbon paper obtained in the step (5) in a single-side spraying mode at the temperature of 120 ℃ in a vacuum environment to obtain composite carbon paper, sintering the composite carbon paper for 1h at the temperature of 400 ℃ in an argon environment, and sintering the composite carbon paper at the temperature of 300 ℃ in the range of 5kg/cm2Hot-pressing for 20s at the pressure of the gas diffusion layer to obtain the gas diffusion layer;
the thickness of the single-side coating is 60 mu m;
the molecular structure diagram of the succinic acid bis-2-ethylhexyl ester sodium sulfonate is shown in fig. 2, and the adsorption structure diagram of the sulfonic acid group hydrocarbon auxiliary agent 3 and the conductive carbon 4 is shown in fig. 3.
Example 3
The embodiment provides a preparation method of a gas diffusion layer, the gas diffusion layer comprises a hydrophobic substrate 1 and a microporous layer 2, the hydrophobic substrate 1 comprises a carbon felt;
the preparation method of the gas diffusion layer comprises the following steps:
(1) shearing, stirring and mixing a graphene and fluorinated ethylene propylene copolymer solution at the temperature of 10 ℃ for 7min at the rotating speed of 20000rpm to obtain a first mixed solution;
in the fluorinated ethylene propylene copolymer solution, the mass percent of the fluorinated ethylene propylene copolymer is 40 wt%, and the mass ratio of the fluorinated ethylene propylene copolymer to the graphene is 1: 2;
(2) shearing, stirring and mixing ethanol and the first mixed solution obtained in the step (1) at the temperature of 10 ℃ and the rotating speed of 20000rpm for 25min to obtain a second mixed solution;
(3) shearing, stirring and mixing the ammonium chloride solution and the second mixed solution obtained in the step (2) at the temperature of 10 ℃ and the rotating speed of 20000rpm for 7min to obtain a third mixed solution;
in the ammonium chloride solution, the mass percent of ammonium chloride is 30 wt%, and the mass ratio of ammonium chloride to graphene is 1: 1.5;
(4) shearing, stirring and mixing the succinic acid bis-2-ethylhexyl ester sodium sulfonate and the third mixed solution obtained in the step (3) at the temperature of 10 ℃ and at the rotating speed of 25000rpm for 15min, and then carrying out ultrasonic treatment at the frequency of 50kHz for 2h to obtain microporous layer slurry with the solid content of 3.5% and the pH value of 6.5;
the sodium bis-2-ethylhexyl sulfosuccinate comprises 2.5 wt% of the microporous layer slurry; in the microporous layer slurry, the carbon loading of graphene is 2.5mg/cm2；
(5) Soaking the carbon felt in 15 wt% fluorinated ethylene propylene copolymer solution at 35 ℃, and drying in an oven at 350 ℃ for 1.5h to obtain a pretreated carbon felt;
the time of single impregnation is 15min, and after the single impregnation is finished, the fresh fluorinated ethylene propylene copolymer solution is replaced, and the impregnation times are 5 times; the thickness of the carbon felt after pretreatment is 140 mu m, the content of the fluorinated ethylene propylene copolymer is 7 wt%, and the porosity is 65%;
(6) coating the microporous layer slurry obtained in the step (4) on the pretreated carbon felt obtained in the step (5) in a single-surface screen printing mode at the temperature of 110 ℃ in a vacuum environment to obtain a composite carbon felt, sintering the composite carbon felt for 1.5 hours at the temperature of 350 ℃ in an argon environment, and sintering the composite carbon felt at the temperature of 250 ℃ and 7kg/cm2Hot pressing for 15s under the pressure of the gas diffusion layer to obtain the gas diffusion layer;
the thickness of the single-side coating is 40 mu m;
the molecular structure diagram of the succinic acid bis-2-ethylhexyl ester sodium sulfonate is shown in figure 2, and the adsorption structure diagram of the sulfonic acid group hydrocarbon auxiliary agent 3 and the conductive carbon 4 is shown in figure 3.
Example 4
The present embodiment provides a method for preparing a gas diffusion layer, the gas diffusion layer comprising a hydrophobic substrate 1 and a microporous layer 2, the hydrophobic substrate 1 comprising carbon paper;
the preparation method of the gas diffusion layer is the same as that of the embodiment 1 except that the mass of the succinic acid bis-2-ethylhexyl ester sodium sulfonate and the like in the step (4) is replaced by the mass of the dibutyl benzene sodium sulfonate;
fig. 3 shows a schematic diagram of the adsorption structure of the sulfonic acid group hydrocarbon additive 3 and the conductive carbon 4 in this example.
Example 5
The embodiment provides a preparation method of a gas diffusion layer, the gas diffusion layer comprises a hydrophobic substrate 1 and a microporous layer 2, the hydrophobic substrate 1 comprises carbon paper;
the preparation method of the gas diffusion layer is the same as that in the example 1 except that the sodium bis-2-ethylhexyl sulfosuccinate and the like in the step (4) are replaced by sodium lignosulfonate in mass;
fig. 3 shows a schematic diagram of the adsorption structure of the sulfonic acid group hydrocarbon additive 3 and the conductive carbon 4 in this example.
Example 6
The present embodiment provides a method for preparing a gas diffusion layer, the gas diffusion layer comprising a hydrophobic substrate 1 and a microporous layer 2, the hydrophobic substrate 1 comprising carbon paper;
the preparation method of the gas diffusion layer is the same as that of the embodiment 1 except that the sodium bis-2-ethylhexyl sulfosuccinate and the like in the step (4) are replaced by sodium polystyrene sulfonate;
fig. 3 shows a schematic diagram of the adsorption structure of the sulfonic acid group hydrocarbon additive 3 and the conductive carbon 4 in this example.
Example 7
The present embodiment provides a method for preparing a gas diffusion layer, the gas diffusion layer comprising a hydrophobic substrate 1 and a microporous layer 2, the hydrophobic substrate 1 comprising carbon paper;
the preparation method of the gas diffusion layer was the same as that of example 1 except that the solid content of the microporous layer slurry was 1 wt%;
fig. 3 shows a schematic diagram of the adsorption structure of the sulfonic acid group hydrocarbon additive 3 and the conductive carbon 4 in this example.
Example 8
The present embodiment provides a method for preparing a gas diffusion layer, the gas diffusion layer comprising a hydrophobic substrate 1 and a microporous layer 2, the hydrophobic substrate 1 comprising carbon paper;
the preparation method of the gas diffusion layer was the same as that of example 1 except that the solid content of the microporous layer slurry was 6 wt%;
fig. 3 shows a schematic diagram of the adsorption structure of the sulfonic acid group hydrocarbon additive 3 and the conductive carbon 4 in this example.
Example 9
The embodiment provides a preparation method of a gas diffusion layer, the gas diffusion layer comprises a hydrophobic substrate 1 and a microporous layer 2, the hydrophobic substrate 1 comprises carbon paper;
the gas diffusion layer was prepared in the same manner as in example 1 except that sodium bis-2-ethylhexyl sulfosuccinate was used in an amount of 0.01 wt% based on the slurry of the microporous layer to adjust the slurry of the microporous layer to pH 8.5;
fig. 3 shows a schematic diagram of the adsorption structure of the sulfonic acid group hydrocarbon additive 3 and the conductive carbon 4 in this example.
Example 10
The present embodiment provides a method for preparing a gas diffusion layer, the gas diffusion layer comprising a hydrophobic substrate 1 and a microporous layer 2, the hydrophobic substrate 1 comprising carbon paper;
the gas diffusion layer was prepared in the same manner as in example 1 except that sodium bis-2-ethylhexyl sulfosuccinate was used in an amount of 6 wt% of the slurry of the microporous layer so that the slurry of the microporous layer had a pH of 4;
fig. 3 shows a schematic diagram of the adsorption structure of the sulfonic acid group hydrocarbon additive 3 and the conductive carbon 4 in this example.
Example 11
The present embodiment provides a method for preparing a gas diffusion layer, the gas diffusion layer comprising a hydrophobic substrate 1 and a microporous layer 2, the hydrophobic substrate 1 comprising carbon paper;
the preparation method of the gas diffusion layer is the same as that of the embodiment 1 except that the steps (1) to (3) are not subjected to shearing stirring;
fig. 3 shows a schematic diagram of adsorption of the sulfonic acid group hydrocarbon additive 3 and the conductive carbon 4.
Comparative example 1
The present comparative example provides a method of preparing a gas diffusion layer comprising a hydrophobic substrate 1 and a microporous layer 2, the hydrophobic substrate 1 comprising carbon paper;
the gas diffusion layer was prepared in the same manner as in example 1, except that sodium bis-2-ethylhexyl sulfosuccinate was not included in the microporous layer slurry.
Comparative example 2
The present comparative example provides a method of preparing a gas diffusion layer comprising a hydrophobic substrate 1 and a microporous layer 2, the hydrophobic substrate 1 comprising carbon paper;
the preparation method of the gas diffusion layer is the same as that of example 1 except that sodium bis-2-ethylhexyl sulfosuccinate and the like are replaced by sodium dodecyl sulfate.
The gas diffusion layers provided in the above examples and comparative examples were subjected to resistivity, porosity, gas permeability and size of the slurry particle diameter of the microporous layer according to the national standard GB20042.7, and the test results are shown in table 1.
The fuel cell is prepared by adopting the conventional process steps, wherein the cathode adopts a Mandarin 13100 type catalyst (the mass fraction of platinum is 60 percent, and the platinum loading is 0.35 mg/cm)2) The ionic polymer is Nafion solution (DuPont 520) with the mass fraction of 5%, the mass ratio of the mass of the ionic polymer to the carbon in the catalyst is 0.85:1, and the solvent is water and isopropanol with the volume ratio of 7: 13; the anode adopts a Zuanxin 9100 type catalyst (the mass fraction of platinum is 40 percent, and the platinum loading capacity is 0.08mg/cm2) The ionic polymer is a Nafion solution (DuPont 520) with the mass fraction of 5%, the mass ratio of the mass of the ionic polymer to the carbon in the catalyst is 0.80:1, and the solvent is water and isopropanol with the volume ratio of 7: 13; the proton membrane is 15 mu mNafion membrane (gor M775.15); the resulting fuel cell was subjected to a polarization curve test in which the area of the fuel cell was 25cm2The temperature was 75 ℃, the hydrogen/air stoichiometric ratio was 1.5/2.0, the cathode and anode humidity RH was 60% and the back pressure was 100kPa, and the test results are shown in table 2.
TABLE 1
TABLE 2
From tables 1 and 2, the following points can be seen:
(1) from the embodiment 1 and the embodiments 7 to 8, it is known that the solid content of the slurry of the microporous layer in the embodiments 7 to 8 is not in the preferable range, and the comprehensive performance of the gas diffusion layer provided in the embodiments 7 to 8 is reduced compared with the embodiment 1; therefore, the solid content of the slurry of the microporous layer is in the preferable range, which is beneficial to improving the comprehensive performance of the gas diffusion layer.
(2) As can be seen from examples 1 and 9 to 10, in the slurry for a microporous layer described in examples 9 to 10, the content of the sulfonic acid group hydrocarbon assistant is not in the preferred range, so that the pH of the slurry for a microporous layer is not in the preferred range, and the overall performance of the gas diffusion layer provided in examples 9 to 10 is reduced as compared with example 1; from this, it is found that the content of the sulfonic acid group hydrocarbon additive in the microporous layer slurry and the pH of the microporous layer slurry are in the preferable ranges, which is advantageous for improving the overall performance of the gas diffusion layer.
(3) As is clear from examples 1 and 11, in example 11, no shear stirring was performed in any of steps (1) to (3), and the overall performance of the gas diffusion layer provided in example 11 was lower than that of example 1; therefore, in the preparation process of the microporous layer slurry, the slurry is fully dispersed, so that the particle size of slurry particles is reduced, the agglomeration of the particles is reduced, and the comprehensive performance of the gas diffusion layer is improved.
(4) As can be seen from example 1 and comparative example 1, the slurry of the microporous layer described in comparative example 1, to which no sulfonic acid group hydrocarbon additive is added, has a significantly reduced overall performance of the gas diffusion layer provided in comparative example 1 compared to example 1; therefore, the sulfonic hydrocarbon auxiliary agent can establish an energy barrier to reduce the agglomeration among particles in the microporous layer slurry, can obviously improve the gas permeability and water removal in the gas diffusion layer, and reduces the resistance of the gas diffusion layer, thereby being beneficial to reducing the ohmic polarization and concentration polarization of the battery and improving the power requirement of the battery under high current density.
(5) As can be seen from examples 1 and 2, the microporous layer slurry of comparative example 2 added sodium dodecylsulfate, which was not able to form C-O-SO with conductive carbon2R structure, the gas diffusion layer provided in comparative example 2 has a significantly reduced overall performance compared to example 1; therefore, the sulfonic hydrocarbon assistant provided by the invention can generate electricity with conductive carbonTo C-O-SO2the-R structure establishes an energy barrier to reduce the agglomeration among particles in the slurry of the microporous layer, thereby improving the gas permeability and water removal in the gas diffusion layer, reducing the resistance of the gas diffusion layer, contributing to reducing the ohmic polarization and concentration polarization of the battery and improving the power requirement of the battery under high current density.
In summary, the present invention provides a gas diffusion layer, a method for preparing the same, and applications of the same, wherein the method for preparing the same comprises the following steps: coating the microporous layer slurry on a hydrophobic substrate to obtain the gas diffusion layer; the microporous layer slurry is obtained by mixing conductive carbon and a sulfonic hydrocarbon auxiliary agent; the sulfonic hydrocarbon assistant comprises any one or the combination of at least two of succinic acid bis-2-ethylhexyl ester sodium sulfonate, dibutyl benzene sodium sulfonate, sodium lignin sulfonate, condensed naphthalene sodium sulfonate or polystyrene sodium sulfonate. The invention adopts sulfonic acid group hydrocarbon auxiliary agent, the sulfonic acid group of which is taken as a polar end, and forms strong physical adsorption and chemical adsorption with the surface of conductive carbon, wherein the physical adsorption utilizes coulomb force adsorption, and the chemical adsorption is that oxygen in the sulfonic acid group and active groups on the surface of the conductive carbon are chemically adsorbed to generate C-O-SO2-R "such that the sulfonic hydrocarbon adjuvant is coated on the surface of the conductive carbon particles to resist the attractive forces between the conductive carbon particles and to create an energy barrier to reduce interparticle agglomeration in the microporous layer slurry; meanwhile, after adsorption is formed when the consumption of the sulfonic hydrocarbon auxiliary agent is saturated, a steric barrier is provided to form a steric hindrance effect, so that the agglomeration among particles is reduced; the sulfonic hydrocarbon additive can be discharged by high-temperature drying decomposition after being coated on the microporous layer slurry; the microporous layer can obviously improve the permeability of gas and the removal of water in the gas diffusion layer and reduce the resistance of the gas diffusion layer, thereby being beneficial to reducing the ohmic polarization and the concentration polarization of the battery and improving the power requirement of the battery under high current density, and the slurry of the microporous layer has good dispersibility, is not easy to agglomerate, has long stabilization time and can be stably maintained for more than 48 hours.
The above description is only for the specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the protection scope and the disclosure of the present invention.
Claims (10)
1. A method of preparing a gas diffusion layer, comprising the steps of:
coating the microporous layer slurry on a hydrophobic substrate to obtain the gas diffusion layer;
the microporous layer slurry is obtained by mixing conductive carbon and a sulfonic hydrocarbon auxiliary agent;
the sulfonic hydrocarbon assistant comprises any one or the combination of at least two of succinic acid bis-2-ethylhexyl ester sodium sulfonate, dibutyl benzene sodium sulfonate, sodium lignin sulfonate, condensed naphthalene sodium sulfonate or polystyrene sodium sulfonate.
2. The preparation method according to claim 1, wherein the sulfonic acid group hydrocarbon additive accounts for 0.05-5 wt% of the microporous layer slurry;
preferably, the solid content of the microporous layer slurry is 2-5 wt%;
preferably, the pH value of the microporous layer slurry is 5-8;
preferably, the conductive carbon comprises any one or a combination of at least two of conductive carbon black, carbon fiber, carbon nanotube or graphene material;
preferably, the carbon loading of the conductive carbon in the microporous layer slurry is 0.7-5 mg/cm2。
3. The preparation method according to claim 1 or 2, wherein the microporous layer slurry further comprises a water repellent, a pore-forming agent and a solvent;
preferably, the water repellent comprises any one of or a combination of at least two of polytetrafluoroethylene, fluorinated ethylene propylene copolymer, polyvinylidene fluoride emulsion or polyhexafluoropropylene emulsion;
preferably, the pore-forming agent comprises PEG-200, PEG-400, ammonium oxalate, lithium carbonate, ammonium chloride, ((II), (III), (IV), (V) and (V), (VNH4)2CO3、(NH4)HCO3Any one or combination of at least two of glucose, L-arabinose or ethyl acetate;
preferably, the solvent comprises any one of deionized water, ethylene glycol, n-propanol, ethanol or NMP or a combination of at least two thereof;
preferably, the mass ratio of the water repellent to the conductive carbon is 1 (1-3);
preferably, the mass ratio of the pore-forming agent to the conductive carbon is 1 (1-3).
4. The method according to claim 3, wherein the microporous layer slurry is obtained by:
(1) mixing conductive carbon and water repellent emulsion for 5-10 min to obtain a first mixed solution;
(2) mixing a solvent with the first mixed solution obtained in the step (1) for 20-30 min to obtain a second mixed solution;
(3) mixing the pore-forming agent solution with the second mixed solution obtained in the step (2) for 5-10 min to obtain a third mixed solution;
(4) and (4) mixing the sulfonic hydrocarbon assistant with the third mixed solution obtained in the step (3) for 10-15 min, and then carrying out ultrasonic treatment for 1-2 h to obtain the microporous layer slurry.
5. The preparation method according to claim 4, wherein the mixing manner comprises any one or a combination of at least two of stirring paddle stirring, magnetic stirring or shear stirring;
preferably, the mixing speed is 5000-25000 rpm, and the temperature is-5-15 ℃;
preferably, in the water repellent emulsion in the step (1), the mass percent of the water repellent is 10-65 wt%;
preferably, in the pore-forming agent solution in the step (3), the mass percentage of the pore-forming agent is 10-70 wt%;
preferably, the frequency of the ultrasound in the step (4) is 20-50 kHz.
6. The preparation method according to any one of claims 1 to 5, wherein the hydrophobic substrate comprises any one or a combination of at least two of carbon paper, carbon felt, carbon fiber paper, carbon fiber woven cloth, a mesh titanium substrate, a mesh nickel substrate and a mesh copper substrate;
preferably, the hydrophobic substrate is pretreated before use, and the pretreatment method comprises the following steps: dipping the hydrophobic substrate into 10-20 wt% of water repellent emulsion, and drying to obtain a pretreated hydrophobic substrate;
preferably, the dipping times are 2-8 times, and the temperature is 30-40 ℃;
preferably, the time for single dipping is 10-20 min;
preferably, the drying temperature is 250-450 ℃, and the drying time is 1-2 h;
preferably, the thickness of the hydrophobic substrate after pretreatment is 130-150 mu m, the content of the water repellent is 3-10 wt%, and the porosity is 60-70%.
7. The preparation method according to any one of claims 1 to 6, wherein the coating method comprises any one or a combination of at least two of screen printing, spraying, manual painting, slit extrusion or roll printing;
preferably, the coating is a single-sided coating;
preferably, the coating environment is a vacuum environment, and the temperature is 100-120 ℃;
preferably, the thickness of the coating is 10-60 μm;
preferably, the coating also comprises sintering and hot pressing treatment which are sequentially carried out;
preferably, the sintering temperature is 300-400 ℃, and the time is 1-2 h;
preferably, the temperature of the hot-pressing treatment is 200-300 ℃, and the pressure is 5-10 kg/cm2The time is 10 to 20 seconds.
8. The production method according to any one of claims 1 to 7, characterized by comprising the steps of:
(1) stirring and mixing the conductive carbon and the water repellent emulsion at the temperature of-5-15 ℃ and the rotating speed of 5000-25000 rpm for 5-10 min to obtain a first mixed solution;
in the water repellent emulsion, the mass percent of the water repellent is 10-65 wt%, and the mass ratio of the water repellent to the conductive carbon is 1 (1-3);
(2) stirring and mixing a solvent and the first mixed solution obtained in the step (1) at a temperature of-5-15 ℃ and a rotating speed of 5000-25000 rpm for 20-30 min to obtain a second mixed solution;
(3) stirring and mixing the pore-forming agent solution and the second mixed solution obtained in the step (2) at a temperature of-5-15 ℃ and a rotating speed of 5000-25000 rpm for 5-10 min to obtain a third mixed solution;
in the pore-forming agent solution, the mass percent of the pore-forming agent is 10-70 wt%, and the mass ratio of the pore-forming agent to the conductive carbon is 1 (1-3);
(4) stirring and mixing the sulfonic hydrocarbon auxiliary agent and the third mixed solution obtained in the step (3) at a temperature of-5-15 ℃ at a rotating speed of 5000-25000 rpm for 10-15 min, and then carrying out ultrasonic treatment at a frequency of 20-50 kHz for 1-2 h to obtain microporous layer slurry with a solid content of 2-5 wt% and a pH value of 5-8;
the sulfonic hydrocarbon auxiliary agent accounts for 0.05-5 wt% of the microporous layer slurry; in the microporous layer slurry, the carbon loading of the conductive carbon is 0.7-5 mg/cm2；
(5) Coating microporous layer slurry with the thickness of 10-60 mu m on one side of a hydrophobic substrate at the temperature of 100-120 ℃ in a vacuum environment, sintering the obtained composite hydrophobic substrate for 1-2 hours at the temperature of 300-400 ℃, and then sintering at the temperature of 200-300 ℃ and the temperature of 5-10 kg/cm2Carrying out hot pressing for 10-20 s under the pressure to obtain the gas diffusion layer;
the hydrophobic substrate is pretreated, and the pretreatment method comprises the following steps: dipping a hydrophobic substrate in 10-20 wt% of water repellent emulsion for 2-8 times at the temperature of 30-40 ℃, and then drying for 1-2 h at the temperature of 250-450 ℃ to finish pretreatment; the time of single dipping is 10-20 min; the thickness of the pretreated hydrophobic substrate is 130-150 mu m, the content of the water repellent is 3-10 wt%, and the porosity is 60-70%.
9. A gas diffusion layer obtained by the production method according to any one of claims 1 to 8, wherein the gas diffusion layer comprises a hydrophobic substrate and a microporous layer.
10. A fuel cell comprising the gas diffusion layer of claim 9.
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