Preparation method of gas diffusion layer material

Abstract

The invention relates to a preparation method of a gas diffusion layer material, and belongs to the technical field of electrochemistry. The preparation method comprises the following steps: uniformly mixing ablatable template fibers and common carbon fibers according to a certain proportion, making the mixed fibers into carbon paper raw paper by using a fiber web forming technology, and then carrying out processes of modified resin impregnation, hot-pressing curing, carbonization graphitization and the like to obtain a substrate layer of a gas diffusion layer material. Different from a traditional gas diffusion layer material preparation process, the substrate layer is not subjected to hydrophobic treatment, and the surface of the substrate layer is directly coated with the hydrophobic microporous layer.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemistry and relates to a method for preparing a gas diffusion layer material. Background Art

[0002] A fuel cell is a power generation device that, under certain operating conditions, converts chemical energy into electrical energy through electrochemical reactions at the two electrodes, supplying hydrogen to the anode and oxygen to the cathode. It boasts significant advantages such as high efficiency, zero pollution, low noise, high reliability, modularity, and rapid response to load changes. The gas diffusion layer (GDL) in a fuel cell plays an important role in supporting the catalyst layer, collecting current, conducting gas and heat, and removing the water generated by the reaction. GDLs typically need to meet the following requirements: a porous structure with good air permeability; low resistivity and strong electron conductivity; high surface flatness and low contact resistance; and sufficient mechanical strength, chemical stability, and high thermal stability.

[0003] In practical applications, the power output of fuel cell systems is constantly changing, sometimes even dramatically. Correspondingly, the amount of hydrogen and oxygen required for the electrochemical reaction, and the corresponding amount of water generated, also varies. If the GDL fails to effectively ensure a timely supply of hydrogen or oxygen, or fails to promptly remove the generated water and heat, the fuel cell system's power output can plummet at best, or even lead to system flooding, shutdown, or even system failure. To meet these requirements, fuel cell systems generally utilize GDL materials with high gas / liquid permeability. The gas / liquid permeability of GDL materials is typically measured by the gas or liquid flow rate per unit area of ​​the GDL material at a given pressure. Generally speaking, the main factors limiting the GDL flow rate are: first, the thickness of the GDL. The thicker the layer, the longer the diffusion paths for gas and liquid, resulting in reduced gas / liquid diffusion. However, to maintain sufficient strength, the GDL material must have a certain thickness, so the flow rate of the GDL material has a certain limit. Second, the number of effective gas / liquid permeable channels in the GDL is limited. However, since both gas and liquid in the GDL can pass through these channels, competition between the gas and liquid phases creates a channel competition, limiting the overall gas or liquid flow rate of the GDL material. Furthermore, GDL materials are often made from carbon fiber as the primary raw material, densified using thermosetting polymer resins such as phenolic, furfural, or furan resins as cracked carbon sources. Sometimes, conductive carbon fillers are added to improve conductivity. However, this additional carbon source can also hinder gas or liquid flow.

[0004] To improve the gas / liquid flow performance of gas diffusion layer materials and alleviate the conflicting pathways between them, researchers have designed hydrophilic and hydrophobic regions on the gas diffusion layer materials, guiding the liquid and gas to travel between the corresponding hydrophilic and hydrophobic regions. CN 114824296A first uses hydrogen peroxide, potassium permanganate, or potassium dichromate as hydrophilic modifiers for carbon fibers, then treats the gas diffusion layer material with polytetrafluoroethylene emulsion, fluorinated ethylene propylene copolymer, polyvinylidene fluoride emulsion, or polyhexafluoropropylene emulsion as a hydrophobic agent, forming hydrophilic and hydrophobic regions on the diffusion layer to achieve separate gas / liquid transmission. CN 113851659A hydrophilically modifies the gas diffusion layer material by injecting an oxidizing solution into a regularly arranged perforated template, forming a gas diffusion layer material with alternating hydrophilic and hydrophobic regions. CN 111129507A forms hydrophilic regions on the hydrophobic-treated gas diffusion layer using hydrophilic small molecules to form a hydrophilic membrane structure. CN110614742A covers the strip grooves of the mold with hydrophobic carbon slurry or hydrophilic carbon slurry at intervals, and then sinters it, and finally forms hydrophobic microporous layers and hydrophilic microporous layers with equal width and thickness on the base layer, and finally forms regularly distributed hydrophilic / hydrophobic areas.

[0005] In addition, Chinese patent CN113889627A discloses a gas diffusion layer, its preparation method, and its application. The microporous layer of the gas diffusion layer is made of hollow porous carbon fibers and a hydrophobic agent, which improves air permeability. The microporous layer of CN 116525840A is provided with first and second regions having corresponding first and second pore sizes. In response to the capillary pressure of the liquid water exceeding the first capillary pressure, liquid water from the catalyst layer enters the first region, accelerating drainage. In response to the capillary pressure of the liquid water exceeding the second capillary pressure, the liquid water enters the second region, hindering its transfer.

[0006] In order to alleviate the competition for gas and liquid pathways in the gas diffusion layer material, the present invention uses a mixture of ordinary carbon fibers and ablative template fibers to produce the base layer of the gas diffusion layer. After the base layer molding processes such as fiber meshing, resin dipping, and sintering, the ablative fibers are removed, leaving a cavity in situ. In particular, the ablative fibers contain nanoparticles, which remain on the surface of the cavity after ablation to form a hydrophobic micro-nanostructure. When the hydrophobic cavity with a micro-nanostructure demonstrated by the present invention is used in the base layer of the gas diffusion layer, it can achieve separate transmission of gas and liquid, significantly improving the problem of competition for gas and liquid pathways: first, due to the hydrophobicity of the cavity, the cavity can only allow gas to pass through; second, because the present invention does not use the hydrophobic treatment process in the traditional gas diffusion layer manufacturing process, the water generated inside the fuel cell can flow out through the pores and holes between the ordinary carbon fibers with the help of capillary force. Summary of the Invention

[0007] The object of the present invention is to provide a method for preparing a gas diffusion layer material, which has the characteristics of good electrical conductivity.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A method for preparing a gas diffusion layer material, the specific process of the method for preparing the gas diffusion layer material is as follows:

[0010] S1: Preparation of ablative template fibers

[0011] A polymer-based spinning solution and nanoparticles are mixed in proportion, wherein the polymer-based spinning solution accounts for 96-97% and the nanoparticles account for 3-4%. The fibers are spun by a spinning technique to obtain polymer-based fibers containing nanoparticles. The obtained fibers are chopped to obtain ablative template fibers with a length of 3 mm.

[0012] S2: Carbon paper forming

[0013] The ablative template fiber prepared in S1 is mixed with carbon fiber and water-soluble fiber in a ratio of 5-8%, 82-85%, and 10%, 5-10 wt% of a surfactant and 0.8-1.2 wt% of a defoamer are added, and the mixture is dispersed in deionized water. The mixture is stirred in water at a speed of 2000-3000 r / min for 30-60 min until the fibers are uniformly mixed, and the mixed fiber is then transferred to a sheet forming machine to form a carbon paper base.

[0014] S3: Resin Impregnation

[0015] The resin, nanoporous carbon fiber, organic solvent, and epoxy soybean oil components are uniformly mixed in a ratio of 15%, 5%, 78%, and 2% to obtain a mixed solution, and the carbon paper base paper prepared in S2 is immersed in the mixed solution for 6 minutes. After the impregnation is completed, the base paper is taken out and allowed to stand on a tray for 15 minutes, and then placed in an oven and dried at 80-150° C. for 30-60 minutes to obtain the resin-impregnated carbon paper;

[0016] S4: Hot pressing curing-carbonization and graphitization

[0017] The carbon paper prepared in S3 is cut into a size of 20cm*20cm, laid flat and then subjected to hot pressing curing treatment at a pressure of 8-10MPa and a temperature of 150-180°C for 10-15min. The carbon paper after hot pressing curing is carbonized. In a nitrogen atmosphere, the temperature is increased from room temperature to 900°C at a rate of 20°C / min. After reaching 900°C, the temperature is kept constant for 2h. After the treatment is completed, the temperature is slowly cooled to room temperature. The treated carbon paper is taken out and the carbonized carbon paper is further graphitized. In an argon atmosphere, the first stage is to quickly increase the temperature from room temperature to 800-1600°C and keep the temperature constant for 0.5h. In the second stage, the temperature is adjusted to 10°C / min, increased to 2500°C, kept constant for 2h, and cooled to room temperature to complete the graphitization treatment of the carbon paper.

[0018] S5: evenly coating one side of the carbon paper treated in S4 with the MPL coating, drying the carbon paper at 110° C. for 4 h, sintering the carbon paper at 350° C. for 10 min, and cooling the carbon paper to room temperature to obtain the gas diffusion layer material;

[0019] The MPL coating preparation method is as follows:

[0020] Dispersing 10-30% by mass of carbon nanomaterial and 5-10% by mass of PTFE emulsion in deionized water, and stirring at a speed of 60-150 r / min for 20-60 min;

[0021] The carbon nanomaterial is one or more of carbon black, flake graphite, and carbon nanotubes.

[0022] Furthermore, the polymer-based spinning solution in S1 is one or more of organic solvent-soluble polymers, water-soluble polymers, natural polymers and derivatives thereof.

[0023] Furthermore, the nanoparticles in S1 are one or more of nanometal oxides, nanocomposite oxides, nanocarbon materials, nanometals and alloys.

[0024] Furthermore, the particle size of the nanoparticles in S1 ranges from 100 to 150 nm.

[0025] Furthermore, the spinning technology in S1 is one of wet spinning and electrospinning.

[0026] Furthermore, the surfactant in S2 is one or more of hydroxymethyl cellulose CMC, polyethylene oxide PEO, hydroxypropyl methyl cellulose HPMC, methyl hydroxyethyl cellulose HEMC, polyvinyl alcohol PVA, and polyvinyl butyral PVB.

[0027] Furthermore, the defoaming agent in S2 is one or more of ethanol, methanol, mineral oil defoaming agent, and polyurethane defoaming agent.

[0028] Furthermore, the resin in S3 is one or more of phenolic resin, epoxy resin, and furan resin.

[0029] Furthermore, the nanoporous carbon fiber in S3 has a length of 0.5 mm and a diameter of ≤100 nm.

[0030] Furthermore, the organic solvent in S3 is one or more of methanol, ethylene glycol, acetone, and anhydrous ethanol.

[0031] The present invention uniformly mixes ablative template fibers and conventional carbon fibers in a specific ratio. Using fiber web forming technology, the mixed fibers are then sheeted into a carbon paper base. The base layer of the gas diffusion layer material is then impregnated with a modified resin, heat-pressed and cured, and carbonized and graphitized to form the base layer. Unlike conventional gas diffusion layer material preparation processes, the base layer of the present invention is not treated with hydrophobicity; instead, the base layer is directly coated with a hydrophobic microporous layer.

[0032] The ablative template fibers added during the preparation of the gas diffusion layer material of the present invention adhere to a layer of resin on their surfaces during resin impregnation. After heat treatment, the impregnated resin carbonizes to form a carbonized shell, while the ablative fibers disappear, leaving behind a cavity of the same shape. The ablative fiber residue adsorbs on the inner surface of the carbonized shell, forming a unique micro-nanostructure. The cavity surface of this micro-nanostructure exhibits strong hydrophobic properties, allowing only gas to pass through. The other carbon fibers in the base layer, untreated, are more hydrophilic than the hydrophobic cavities. Liquid water is more likely to flow out through the pores and holes between these hydrophilic fibers due to capillary forces, thus achieving gas / liquid diversion and transport within the diffusion layer material.

[0033] In the preparation method of the present invention, resin impregnation is intended to enhance the mechanical properties and chemical stability of the carbon paper base, while also improving its electrical conductivity and thermal stability. Resin impregnation forms a specific resin network within the carbon paper base, which strengthens the connection between fibers, thereby improving the carbon paper's tensile strength and wear resistance. The resin, as the primary component of the mixed solution, acts as a bond and strengthens the connections between the fibers. It penetrates into the gaps between the fibers and, upon curing, forms a strong network, thereby improving the mechanical properties and stability of the carbon paper. The nanoporous carbon fibers enhance the carbon paper's electrical conductivity. Their porous structure facilitates electrolyte penetration and ion transport, thereby enhancing battery performance. Furthermore, the nanoporous carbon fibers provide mechanical support and enhance the strength of the carbon paper. The organic solvent, the solvent portion of the mixed solution, is used to disperse the resin and the nanoporous carbon fibers. It makes the mixed solution more uniform, facilitating the even distribution of the resin and carbon fibers within the carbon paper base. During the impregnation process, the organic solvent evaporates, leaving behind a network formed by the resin and carbon fibers. The epoxidized soybean oil component acts as a plasticizer, enhancing the resin's flexibility and plasticity. It can reduce the brittleness of the resin, making it easier to process and shape. At the same time, the epoxidized soybean oil component can also improve the compatibility between the resin and carbon fiber, strengthening the bonding between them.

[0034] During the preparation of the gas diffusion layer material, the present invention first performs a hot pressing treatment and then a carbonization and graphitization treatment. The hot pressing treatment can enhance the strength and density of the carbon paper base. By allowing the impregnated resin to be more evenly coated on the carbon fibers, the fibers are better bonded, thereby improving the mechanical properties of the carbon paper and providing a stable substrate for subsequent carbonization and graphitization treatments. The hot pressing treatment helps control the thickness and porosity of the carbon paper. These parameters are crucial to the performance of the gas diffusion layer and affect the gas permeability and conductivity. Through hot pressing, these performance parameters can be optimized to meet the requirements of fuel cells for the gas diffusion layer. The carbon paper after hot pressing is more likely to form a uniform structure during the carbonization and graphitization processes. This helps to reduce defects and stress within the material and improve the overall performance and stability of the material. At the same time, the carbonization and graphitization treatments can further enhance the conductivity, thermal stability, and chemical stability of the carbon paper, making it more suitable for applications such as fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0036] Figure 1 Schematic diagram of nanoparticle distribution after graphitization of ablative template fibers;

[0037] Figure 2 Schematic diagram of nanoporous carbon fibers. DETAILED DESCRIPTION

[0038] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0039] Example 1

[0040] S1: Preparation of ablative template fibers

[0041] A PMMA spinning solution was mixed with silica nanoparticles with a particle size of 100 nm in a certain proportion, wherein the PMMA spinning solution was 97% and the silica nanoparticles were 3%. The fibers were spun by electrospinning at a spinning voltage of 28 kV to obtain a polymer-based fiber containing the nanoparticles. The obtained fibers were chopped to obtain a 3 mm long ablative template fiber.

[0042] S2: Carbon paper forming

[0043] The ablative template fiber prepared in S1 was mixed with carbon fiber and water-soluble fiber in a ratio of 5%, 85%, and 10%, 10 wt% of hydroxymethyl cellulose and 0.8 wt% of a silicon-free defoamer were added, and the mixture was dispersed in deionized water. The mixture was stirred in water at a speed of 2000 r / min for 60 min until the fibers were uniformly mixed. The mixed fiber was then transferred to a sheet forming machine to form a carbon paper base.

[0044] S3: Resin Impregnation

[0045] Phenolic resin, nanoporous carbon fiber, methanol, and epoxy soybean oil components are uniformly mixed in a ratio of 15%, 5%, 78%, and 2% to obtain a mixed solution, wherein the nanoporous carbon fiber has a length of 0.5 mm and a diameter of ≤100 nm. The carbon paper base paper prepared by S2 is immersed in the mixed solution for 6 minutes. After the impregnation is completed, it is taken out and allowed to stand on a tray for 15 minutes. It is then placed in an oven and dried at 180°C for 30 minutes to obtain the resin-impregnated carbon paper;

[0046] S4: Hot pressing curing-carbonization and graphitization

[0047] The carbon paper prepared in S3 was cut into a size of 20 cm*20 cm, and then flattened for hot pressing and curing. The hot pressing and curing parameters were pressure 8 MPa, temperature 180°C, and time 12 min. The carbon paper after hot pressing and curing was carbonized. In a nitrogen atmosphere, the temperature was increased from room temperature to 900°C at a rate of 20°C / min. After reaching 900°C, the temperature was kept constant for 2 h. After the treatment was completed, the temperature was slowly cooled to room temperature. The treated carbon paper was taken out and the carbonized carbon paper was further graphitized. In an argon atmosphere, the first stage was to quickly increase the temperature from room temperature to 800°C and keep the temperature constant for 0.5 h. In the second stage, the temperature was adjusted to 10°C / min, increased to 2500°C, and kept the temperature constant for 2 h. After cooling to room temperature, the graphitization of the carbon paper was completed.

[0048] S5: evenly coating one side of the carbon paper treated in S4 with the MPL coating, drying the carbon paper at 110° C. for 4 h, sintering the carbon paper at 350° C. for 10 min, and cooling the carbon paper to room temperature to obtain the gas diffusion layer material;

[0049] The MPL coating preparation method is as follows:

[0050] 10% carbon black and 2% carbon nanotubes were mixed and dispersed in deionized water, 5% PTFE emulsion was added, and the mixture was stirred at a speed of 60 r / min for 60 minutes.

[0051] Example 2

[0052] S1: Preparation of ablative template fibers

[0053] A PMMA spinning solution was mixed with titanium dioxide nanoparticles with a particle size of 120 nm in a certain proportion, wherein the PMMA spinning solution accounted for 97% and the titanium dioxide nanoparticles accounted for 3%. The fibers were spun by electrospinning at a spinning voltage of 28 kV to obtain a polymer-based fiber containing the nanoparticles. The obtained fibers were chopped to obtain a 3 mm long ablative template fiber.

[0054] S2: Carbon paper forming

[0055] The ablative template fiber prepared in S1 was mixed with carbon fiber and water-soluble fiber in a ratio of 5%, 85%, and 10%, 2 wt% of polyvinyl alcohol and 1 wt% of a silicon-free defoamer were added, and the mixture was dispersed in deionized water. The mixture was stirred in water at a speed of 3000 r / min for 40 minutes until the fibers were evenly mixed. The mixed fiber was then transferred to a sheet forming machine to form a carbon paper base.

[0056] S3: Resin Impregnation

[0057] Phenolic resin, nanoporous carbon fiber, ethanol, and epoxy soybean oil components are uniformly mixed in a ratio of 15%, 5%, 78%, and 2% to obtain a mixed solution, wherein the nanoporous carbon fiber has a length of 0.5 mm and a diameter of ≤100 nm. The carbon paper base paper prepared by S2 is immersed in the mixed solution for 6 minutes. After the impregnation is completed, it is taken out and allowed to stand on a tray for 15 minutes. It is then placed in an oven and dried at 80°C for 60 minutes to obtain resin-impregnated carbon paper;

[0058] S4: Hot pressing curing-carbonization and graphitization

[0059] The carbon paper prepared in S3 was cut into a size of 20 cm*20 cm, and then flattened for hot pressing and curing. The hot pressing and curing parameters were a pressure of 10 MPa, a temperature of 150°C, and a duration of 10 min. The carbon paper after hot pressing and curing was carbonized. In a nitrogen atmosphere, the temperature was increased from room temperature to 900°C at a rate of 20°C / min. After reaching 900°C, the temperature was kept constant for 2 hours. After the treatment was completed, the temperature was slowly cooled to room temperature. The treated carbon paper was taken out, and the carbonized carbon paper was further graphitized. In an argon atmosphere, the first stage was to quickly increase the temperature from room temperature to 1200°C and keep the temperature constant for 0.5h. In the second stage, the temperature was adjusted to 10°C / min, increased to 2500°C, and kept the temperature constant for 2h. After cooling to room temperature, the graphitization of the carbon paper was completed.

[0060] S5: evenly coating one side of the carbon paper treated in S4 with the MPL coating, drying the carbon paper at 110° C. for 4 h, sintering the carbon paper at 350° C. for 10 min, and cooling the carbon paper to room temperature to obtain the gas diffusion layer material;

[0061] The MPL coating preparation method is as follows:

[0062] 30% flake graphite was dispersed in deionized water, 5% PTFE emulsion was added, and the mixture was stirred at a speed of 80 r / min for 40 min.

[0063] Example 3

[0064] S1: Preparation of ablative template fibers

[0065] A PMMA spinning solution and titanium dioxide nanoparticles with a particle size of 150 nm are mixed in a proportion, wherein the PMMA spinning solution accounts for 96% and the titanium dioxide nanoparticles account for 4%. The mixed solution is spun using a wet spinning technique. The mixed solution is injected into a spinning machine, metered by a metering pump, and then enters a spinneret through a candle filter and a connecting tube. A thin stream of the stock solution is squeezed out of the spinneret and enters a coagulation bath, where it precipitates to form a high-molecular polymer-based fiber containing the nanoparticles. The resulting fiber is chopped to obtain an ablative template fiber with a length of 3 mm.

[0066] S2: Carbon paper forming

[0067] The ablative template fiber prepared in S1 was mixed with carbon fiber and water-soluble fiber in a ratio of 5%, 85%, and 10%, 5wt% hydroxypropyl methylcellulose and 1.2wt% silicon-free defoamer were added, and the mixture was dispersed in deionized water. The mixture was stirred in water at a speed of 3000 r / min for 30 minutes until the fibers were evenly mixed. The mixed fiber was then transferred to a sheet forming machine to form a carbon paper base.

[0068] S3: Resin Impregnation

[0069] Phenolic resin, nanoporous carbon fiber, ethylene glycol, and epoxy soybean oil components are uniformly mixed in a ratio of 15%, 5%, 78%, and 2% to obtain a mixed solution, wherein the nanoporous carbon fiber has a length of 0.5 mm and a diameter of ≤100 nm. The carbon paper base paper prepared in S2 is immersed in the mixed solution for 6 minutes. After the impregnation is completed, it is taken out and allowed to stand on a tray for 15 minutes. It is then placed in an oven and dried at 120°C for 45 minutes to obtain resin-impregnated carbon paper;

[0070] S4: Hot pressing curing-carbonization and graphitization

[0071] The carbon paper prepared in S3 was cut into a size of 20 cm*20 cm, and then flattened for hot pressing and curing. The hot pressing and curing parameters were pressure 9 MPa, temperature 150°C, and time 15 min. The carbon paper after hot pressing and curing was carbonized. In a nitrogen atmosphere, the temperature was increased from room temperature to 900°C at a rate of 20°C / min. After reaching 900°C, the temperature was kept constant for 2 h. After the treatment was completed, the temperature was slowly cooled to room temperature. The treated carbon paper was taken out and the carbonized carbon paper was further graphitized. In an argon atmosphere, the first stage was to quickly increase the temperature from room temperature to 1600°C and keep the temperature constant for 0.5 h. In the second stage, the temperature was adjusted to 10°C / min, increased to 2500°C, and kept the temperature constant for 2 h. After cooling to room temperature, the graphitization of the carbon paper was completed.

[0072] S5: evenly coating one side of the carbon paper treated in S4 with MPL coating, drying the carbon paper at 110° C. for 4 h, sintering the carbon paper at 350° C. for 10 min, and cooling the carbon paper to room temperature to obtain the gas diffusion layer material.

[0073] The MPL coating preparation method is as follows:

[0074] 20% carbon nanotubes were dispersed in deionized water, 8% PTFE emulsion was added, and the mixture was stirred at a speed of 120 r / min for 30 min.

[0075] Comparative Example 1

[0076] S1: Preparation of porous carbon fibers

[0077] The PAN-based spinning solution and the PMMA spinning solution were mixed in proportion, wherein the PAN-based spinning solution accounted for 85% and the PMMA spinning solution accounted for 15%, and the fibers were spun by electrospinning technology at a spinning voltage of 28 kV and carbonized at 900 ° C to form porous carbon fibers.

[0078] S2: Carbon paper forming

[0079] The ablative template fiber prepared in S1 was mixed with carbon fiber and water-soluble fiber in a ratio of 5%, 85%, and 10%, 5wt% polyvinyl alcohol and 0.8wt% silicon-free defoamer were added, and the mixture was dispersed in deionized water. The mixture was stirred in water at a speed of 3000 r / min for 30 minutes until the fibers were evenly mixed. The mixed fiber was then transferred to a sheet forming machine to form a carbon paper base.

[0080] S3: Resin Impregnation

[0081] Phenolic resin and methanol were mixed in a ratio of 20% and 80% to obtain a mixed solution, and the carbon paper prepared in S2 was immersed in the mixed solution for 6 minutes. After the impregnation was completed, the carbon paper was taken out and allowed to stand on a tray for 15 minutes, and then placed in an oven and dried at 120°C for 45 minutes to obtain the resin-impregnated carbon paper;

[0082] S4: Hot pressing curing-carbonization and graphitization

[0083] The carbon paper prepared in S3 was cut into a size of 20 cm*20 cm, and then flattened for hot pressing and curing. The hot pressing and curing parameters were a pressure of 10 MPa, a temperature of 160°C, and a duration of 15 min. The carbon paper after hot pressing and curing was carbonized. In a nitrogen atmosphere, the temperature was increased from room temperature to 900°C at a rate of 20°C / min. After reaching 900°C, the temperature was kept constant for 2 hours. After the treatment was completed, the temperature was slowly cooled to room temperature. The treated carbon paper was taken out and the carbonized carbon paper was further graphitized. In an argon atmosphere, the first stage was to quickly increase the temperature from room temperature to 800°C and keep the temperature constant for 0.5h. In the second stage, the temperature was adjusted to 10°C / min, increased to 2500°C, and kept the temperature constant for 2h. After cooling to room temperature, the graphitization of the carbon paper was completed.

[0084] S5: The carbon paper treated in S4 is immersed in a PTFE emulsion for 5 minutes, taken out, and dried in an oven, wherein the PTFE emulsion concentration is 10%. Then, one side of the dried carbon paper is evenly coated with an MPL coating, and dried at 110° C. for 4 hours. After drying, the carbon paper is sintered at 350° C. for 10 minutes. After sintering, the carbon paper is cooled to room temperature to obtain the gas diffusion layer material.

[0085] The MPL coating preparation method is as follows:

[0086] 10% flake graphite and 2% carbon nanotubes were dispersed in deionized water, 10% PTFE emulsion was added, and the mixture was stirred at a speed of 150 r / min for 20 minutes.

[0087] Comparative Example 2

[0088] S1: Carbon paper forming

[0089] The ablative template fiber prepared in S1 was mixed with carbon fiber and water-soluble fiber in a ratio of 5%, 85%, and 10%, 6wt% of hydroxypropyl methylcellulose and 1.2wt% of a silicon-free defoamer were added, and the mixture was dispersed in deionized water. The mixture was stirred in water at a speed of 3000 r / min for 45 minutes until the fibers were evenly mixed. The mixed fibers were then transferred to a sheet forming machine to form a carbon paper base.

[0090] S2: Resin Impregnation

[0091] Phenolic resin, nanoporous carbon fiber, and methanol were uniformly mixed in a ratio of 15%, 5%, and 80% to obtain a mixed solution. The carbon paper prepared in S1 was immersed in the mixed solution for 6 minutes. After the impregnation was completed, the carbon paper was taken out and allowed to stand on a tray for 15 minutes. The carbon paper was placed in an oven and dried at 150°C for 50 minutes to obtain the resin-impregnated carbon paper.

[0092] S3: Hot pressing curing-carbonization and graphitization

[0093] The carbon paper prepared in S2 was cut into a size of 20 cm*20 cm, and then flattened for hot pressing and curing. The hot pressing and curing parameters were a pressure of 10 MPa, a temperature of 160°C, and a duration of 15 min. The carbon paper after hot pressing and curing was carbonized. In a nitrogen atmosphere, the temperature was increased from room temperature to 900°C at a rate of 20°C / min. After reaching 900°C, the temperature was kept constant for 2 hours. After the treatment was completed, the temperature was slowly cooled to room temperature. The treated carbon paper was taken out, and the carbonized carbon paper was further graphitized. In an argon atmosphere, the first stage was to quickly increase the temperature from room temperature to 800°C and keep the temperature constant for 0.5h. In the second stage, the temperature was adjusted to 10°C / min, increased to 2500°C, and kept the temperature constant for 2h. After cooling to room temperature, the graphitization of the carbon paper was completed.

[0094] S4: The carbon paper treated in S3 is immersed in a PTFE emulsion for 5 minutes, taken out, and placed in an oven for drying, wherein the PTFE emulsion concentration is 10%. Then, one side of the dried carbon paper is evenly coated with an MPL coating and dried at 110° C. for 4 hours. After drying, the carbon paper is sintered at 350° C. for 10 minutes. After sintering, the carbon paper is cooled to room temperature to obtain the gas diffusion layer material.

[0095] The MPL coating preparation method is as follows:

[0096] 20% carbon black was dispersed in deionized water, 10% PTFE emulsion was added, and the mixture was stirred at a speed of 80 r / min for 60 min.

[0097] Comparative Example 3

[0098] S1: Carbon paper forming

[0099] The ablative template fiber prepared in S1 was mixed with carbon fiber and water-soluble fiber in a ratio of 5%, 85%, and 10%, 4wt% of polypropylene butyral and 1wt% of a silicon-free defoamer were added, and the mixture was dispersed in deionized water. The mixture was stirred in water at a speed of 3000 r / min for 60 min until the fibers were uniformly mixed. The mixed fiber was then transferred to a sheet forming machine to form a carbon paper base.

[0100] S2: Resin Impregnation

[0101] Phenolic resin and methanol were mixed in a ratio of 20% and 80% to obtain a mixed solution. The carbon paper prepared in S1 was immersed in the mixed solution for 6 minutes. After the impregnation was completed, the carbon paper was taken out and allowed to stand on a tray for 15 minutes. The carbon paper was placed in an oven and dried at 80°C for 12 hours to obtain the resin-impregnated carbon paper.

[0102] S3: Hot pressing curing-carbonization and graphitization

[0103] The carbon paper prepared in S2 was cut into a size of 20 cm*20 cm, and then flattened for hot pressing and curing. The hot pressing and curing parameters were a pressure of 10 MPa, a temperature of 160°C, and a duration of 15 min. The carbon paper after hot pressing and curing was carbonized. In a nitrogen atmosphere, the temperature was increased from room temperature to 900°C at a rate of 20°C / min. After reaching 900°C, the temperature was kept constant for 2 hours. After the treatment was completed, the temperature was slowly cooled to room temperature. The treated carbon paper was taken out, and the carbonized carbon paper was further graphitized. In an argon atmosphere, the first stage was to quickly increase the temperature from room temperature to 800°C and keep the temperature constant for 0.5h. In the second stage, the temperature was adjusted to 10°C / min, increased to 2500°C, and kept the temperature constant for 2h. After cooling to room temperature, the graphitization of the carbon paper was completed.

[0104] S4: The carbon paper treated in S3 is immersed in a PTFE emulsion for 5 minutes, taken out, and placed in an oven for drying, wherein the PTFE emulsion concentration is 10%. Then, one side of the dried carbon paper is evenly coated with an MPL coating and dried at 110° C. for 4 hours. After drying, the carbon paper is sintered at 350° C. for 10 minutes. After sintering, the carbon paper is cooled to room temperature to obtain the gas diffusion layer material.

[0105] The MPL coating preparation method is as follows:

[0106] 10% carbon black and 10% flake graphite were dispersed in deionized water, 8% PTFE emulsion was added, and the mixture was stirred at a speed of 110 r / min for 50 min.

[0107] The gas diffusion layer materials prepared in the examples and comparative examples were tested for their performance, and the experimental results are summarized in the following table:

[0108]

[0109]

[0110] The above experimental data show that the addition of the ablative template fiber in Examples 1 to 3 significantly reduces the gas permeability resistance and resistivity of the gas diffusion layer, thereby improving the performance of the gas diffusion layer.

[0111] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a gas diffusion layer material, characterized in that: The specific process of the preparation method of the gas diffusion layer material is as follows: S1: Preparation of ablative template fibers A polymer-based spinning solution and nanoparticles are mixed in proportion, wherein the polymer-based spinning solution accounts for 96-97% and the nanoparticles account for 3-4%. The fibers are spun by a spinning technique to obtain polymer-based fibers containing nanoparticles. The obtained fibers are chopped to obtain ablative template fibers with a length of 3 mm. S2: Carbon paper forming The ablative template fiber prepared in S1 is mixed with carbon fiber and water-soluble fiber in a ratio of 5-8%, 82-85%, and 10%, 5-10 wt% of a surfactant and 0.8-1.2 wt% of a defoamer are added, and the mixture is dispersed in deionized water. The mixture is stirred in water at a speed of 2000-3000 r / min for 30-60 min until the fibers are uniformly mixed, and the mixed fiber is then transferred to a sheet forming machine to form a carbon paper base. S3: Resin Impregnation The resin, nanoporous carbon fiber, organic solvent, and epoxy soybean oil components are uniformly mixed in a ratio of 15%, 5%, 78%, and 2% to obtain a mixed solution, and the carbon paper base paper prepared in S2 is immersed in the mixed solution for 6 minutes. After the impregnation is completed, the base paper is taken out and allowed to stand on a tray for 15 minutes, and then placed in an oven and dried at 80-150°C for 30-60 minutes to obtain the resin-impregnated carbon paper; S4: Hot pressing curing-carbonization and graphitization The carbon paper prepared in S3 is cut into a size of 20cm*20cm, and is flattened and then subjected to hot pressing curing treatment. The hot pressing curing parameters are pressure 8-10MPa, temperature 150-180℃, and time 10-15min. The carbon paper after hot pressing curing is carbonized. In a nitrogen atmosphere, the temperature is increased from room temperature to 900℃ at a rate of 20℃ / min. After reaching 900℃, the temperature is kept constant for 2h. After the treatment is completed, the temperature is slowly cooled to room temperature. The treated carbon paper is taken out and the carbonized carbon paper is further graphitized. In an argon atmosphere, the first stage is to quickly heat from room temperature to 800-1600℃ and keep the temperature constant for 0.5h. In the second stage, the heating rate is adjusted to 10℃ / min, the temperature is increased to 2500℃, and the temperature is kept constant for 2h. After cooling to room temperature, the graphitization treatment of the carbon paper is completed. S5: evenly coating one side of the carbon paper treated in S4 with the MPL coating, drying the carbon paper at 110° C. for 4 h, sintering the carbon paper at 350° C. for 10 min, and cooling the carbon paper to room temperature to obtain the gas diffusion layer material; The MPL coating preparation method is as follows: Dispersing 10-30% by mass of carbon conductive material and 5-10% by mass of PTFE emulsion in deionized water, and stirring at a speed of 60-150 r / min for 20-60 minutes; The carbon conductive material is one or more of carbon black, flake graphite, and carbon nanotubes.

2. The method for preparing a gas diffusion layer material according to claim 1, characterized in that: The polymer-based spinning solution in S1 is one or more of organic solvent-soluble polymers, water-soluble polymers, natural polymers and derivatives thereof.

3. The method for preparing a gas diffusion layer material according to claim 1, characterized in that: The nanoparticles in S1 are one or more of nanometal oxides, nanocomposite oxides, nanocarbon materials, nanometals and alloys.

4. The method for preparing a gas diffusion layer material according to claim 1, characterized in that: The particle size of the nanoparticles in S1 ranges from 100 to 150 nm.

5. The method for preparing a gas diffusion layer material according to claim 1, characterized in that: The spinning technology in S1 is one of wet spinning and electrospinning.

6. The method for preparing a gas diffusion layer material according to claim 1, characterized in that: The surfactant in S2 is one or more of hydroxymethyl cellulose CMC, polyethylene oxide PEO, hydroxypropyl methyl cellulose HPMC, methyl hydroxyethyl cellulose HEMC, polyvinyl alcohol PVA, and polyvinyl butyral PVB.

7. The method for preparing a gas diffusion layer material according to claim 1, characterized in that: The defoaming agent in S2 is one or more of ethanol, methanol, mineral oil defoaming agent, and polyurethane defoaming agent.

8. The method for preparing a gas diffusion layer material according to claim 1, characterized in that: The resin in S3 is one or more of phenolic resin, epoxy resin, and furan resin.

9. The method for preparing a gas diffusion layer material according to claim 1, characterized in that: The nanoporous carbon fiber in S3 has a length of 0.5 mm and a diameter of ≤100 nm.

10. The method for preparing a gas diffusion layer material according to claim 1, characterized in that: The organic solvent in S3 is one or more of methanol, ethylene glycol, acetone, and anhydrous ethanol.

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