Gradient porous carbon paper substrate based on impregnation-doping synergistic regulation and preparation method

Abstract

The present application relates to gradient porous carbon paper substrate based on impregnation-doping synergistic regulation and preparation method. The present application comprises mixing resin and conductive carbon black in a predetermined ratio and uniformly dispersing for standby; carbon fiber paper is immersed in impregnation liquid for impregnation, liquid application amount is controlled by using liquid roller, and the first layer of impregnated paper is obtained after drying for standby; carbon fiber paper is immersed in impregnation liquid for impregnation, liquid application amount is controlled by using liquid roller, and the second layer of impregnated paper is obtained after drying for standby; carbon fiber paper is immersed in impregnation liquid for impregnation, liquid application amount is controlled by using liquid roller, and the third layer of impregnated paper is obtained after drying for standby; carbon fiber paper is immersed in impregnation liquid for impregnation, liquid application amount is controlled by using liquid roller, and the n layer of impregnated paper is obtained after drying for standby; the first to n layers of impregnated paper are arranged from small to large in turn, and composite hot pressing is carried out by using hot press, and the cured paper with gradient pores is obtained after heat setting; heat treatment is carried out, and the gradient porous carbon paper substrate is obtained. The present application can optimize gas-liquid transmission path.

Description

Technical Field

[0001] This invention relates to the field of gas diffusion layer (GDL) technology for fuel cells, and in particular to gradient porous carbon paper substrate based on impregnation-doping synergistic regulation and its preparation method. Background Technology

[0002] Fuel cells, as highly efficient energy conversion devices, have broad application prospects in the energy field. Among them, the gas diffusion layer plays a crucial role, requiring excellent permeability, conductivity, and water vapor management capabilities. Carbon paper, as a commonly used gas diffusion layer material, directly affects the performance and lifespan of the fuel cell. Good water vapor management ensures uniform diffusion of reactant gases within the carbon paper, enabling efficient electrochemical reactions in the fuel cell, maintaining a favorable internal reaction environment, and improving the cell's stability and durability. Traditional homogeneous carbon paper suffers from the following drawbacks: uniform pore distribution causes conflicts between gas diffusion and water transport paths, making the cathode prone to flooding; secondly, the lack of functional partitioning in the thickness direction makes it impossible to simultaneously manage gas diffusion on the catalyst layer side and drainage on the bipolar plate side; and the significant difference in pore gradient between the microporous layer and the macropores of the carbon paper results in a large span of capillary forces, hindering drainage.

[0003] Chinese patent CN113322713B discloses a gradient technology that utilizes differences in fiber physical properties to lay out fibers with gradient aspect ratios in layers, forming them using a slanted wire, followed by resin impregnation and finally carbonization to obtain gradient carbon paper. This patent utilizes the Bernoulli effect to improve gas transport efficiency, but it requires complex fiber pretreatment (degumming, oxidation) and specialized layup equipment. Patent CN116732814B utilizes wet lamination combined with fiber length partitioning technology to stack three layers of wet paper, dry and form them, and finally impregnate and hot-press them. It mainly utilizes the stacking of wet paper to enhance interlayer bonding, but dry lamination leads to the risk of "interlayer delamination".

[0004] Therefore, gas-liquid transport can be optimized by adjusting the pore gradient of carbon paper. However, existing adjustment technologies rely on the physical properties of fibers in the raw materials, making pore gradient adjustment difficult and resulting in weak interlayer bonding. Summary of the Invention

[0005] To this end, the present invention provides a gradient porosity carbon paper substrate and preparation method based on the synergistic regulation of impregnation-doping, which realizes a continuous gradual change in porosity in the thickness direction of carbon paper from the catalyst layer contact surface (small pores) to the bipolar plate contact surface (large pores), optimizes the gas-liquid transport path, and achieves multi-objective optimization of conductivity / mass transfer.

[0006] To address the aforementioned technical problems, this invention provides a method for preparing a gradient-porous carbon paper substrate based on synergistic regulation of impregnation and doping, comprising: (1) Preparation of impregnation solution: Mix the resin and conductive carbon black in a predetermined ratio and disperse them evenly for later use; (2) First layer of carbon fiber paper impregnation: The carbon fiber paper is impregnated in the impregnation solution and the amount of adhesive W1 is controlled by the liquid rolling roller. Then it is dried for later use to obtain the first layer of impregnated paper. (3) Impregnation of the second layer of carbon fiber paper: The carbon fiber paper is immersed in the impregnation solution and the amount of adhesive W2 is controlled by the sizing roller. Then it is dried for later use to obtain the second layer of impregnated paper. (4) Impregnation of the third layer of carbon fiber paper: The carbon fiber paper is immersed in the impregnation solution and the amount of glue applied is controlled by the sizing roller W3. Then it is dried for later use to obtain the third layer of impregnated paper. (5) Impregnation of the nth layer of carbon fiber paper with impregnation solution: The carbon fiber paper is impregnated in the impregnation solution and the amount of adhesive Wn is controlled by the liquid rolling roller. Then it is dried for later use to obtain the nth layer of impregnated paper. (6) Composite hot pressing curing: The first to n layers of impregnated paper are arranged in order from small to large, and composite hot pressing is performed using a hot press. After heat curing, the paper is taken out to obtain a cured paper with gradient pores. (7) Heat-treat the cured paper with gradient pores. After the heat treatment is completed, a carbon paper substrate with gradient pores is obtained.

[0007] In one embodiment of the present invention, the resin is one or more of alcohol-soluble phenolic resin, oil-soluble phenolic resin, and modified phenolic resin; the conductive carbon black is at least one of 5-40 wt% XC-72 carbon powder, 5-50 wt% carbon nanotubes, and 5-50 wt% flake graphite, and the ratio of the resin to the conductive carbon black is configured such that the resin ratio is 50%-90% and the corresponding conductive carbon black ratio is 50%-10%.

[0008] In one embodiment of the present invention, in steps (2) to (5), the surface density of the carbon fiber paper is 10 g / m³. 2 -50g / m 2 The thickness is 100μm-500μm; the amount of adhesive applied W1 is 20-50%, the amount of adhesive applied W2 is 50%-80%, the amount of adhesive applied W3 is 80%-110%, and the amount of adhesive applied Wn is 30% of the increase in the amount of the previous layer, where n is 3-6.

[0009] In one embodiment of the present invention, in steps (2) to (5), the drying temperature is 80-120°C and the pressure of the rolling mill is 0.1MPa-0.5MPa.

[0010] In one embodiment of the present invention, in step (6), the temperature of the composite hot pressing is 150℃-200℃, the time is 3min-10min, and the pressure is 0.2MPa-0.7MPa.

[0011] In one embodiment of the present invention, the temperature of the heat treatment in step (7) is 1800℃-2800℃ and the time is 10min-30min.

[0012] This invention provides a gradient porous carbon paper substrate based on the synergistic regulation of impregnation and doping, which is prepared by the aforementioned method for preparing a gradient porous carbon paper substrate based on the synergistic regulation of impregnation and doping.

[0013] In one embodiment of the present invention, the gradient porous carbon paper substrate includes at least two sub-layers, the porosity between adjacent sub-layers varies with a gradient of not less than 5%, and they are arranged sequentially from the microporous layer on the catalyst layer side to the macroporous layer on the bipolar plate side.

[0014] In one embodiment of the present invention, the gradient porous carbon paper substrate has a continuously varying pore size distribution along the thickness direction, the pore size range of the gradient pores is 0-100μm, and the pore size increases by not less than 0.5μm for every 10μm increase in the thickness direction.

[0015] The technical solution of the present invention has the following advantages compared with the prior art: 1. Gradient control is more flexible and efficient Unlike existing technologies that rely on fiber aspect ratio / length to control the pore gradient, which is limited by raw material properties, this invention achieves gradient control through resin loading and material zoning synergy, overcoming raw material limitations and significantly improving the adjustability and design freedom of the pore gradient.

[0016] 2. Significantly improved interlayer bonding strength Existing technologies rely on resin filling or mechanical entanglement, resulting in limited interfacial strength. This invention employs a hot-pressing interlocking process to form a three-dimensional carbon fiber-resin network, significantly enhancing interlayer bonding and improving peel strength.

[0017] 3. Simplified process and reduced cost Existing technologies require specialized layering equipment, resulting in high process complexity. This invention is compatible with the modification of traditional base paper production lines and conventional impregnation lines, eliminating the need for expensive specialized equipment, significantly reducing equipment costs, and facilitating industrialization.

[0018] 4. Multifunctional collaborative optimization Existing technologies can only achieve single-pore gradient functionality. This invention simultaneously optimizes conductivity, mass transfer efficiency, and mechanical strength (such as reducing sheet resistivity), meeting multiple objectives and expanding application scenarios. Attached Figure Description

[0019] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0020] Figure 1 This is a flowchart of a method for preparing gradient porous carbon paper substrate based on the synergistic regulation of impregnation and doping.

[0021] Figure 2 It is a single-cell polarization curve. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0023] In this invention, when directions (up, down, left, right, front, and back) are described, it is only for the purpose of describing the technical solution of this invention, and does not indicate or imply that the technical features referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0024] In this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number. In the description of this invention, the terms "first" and "second" are used only to distinguish technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0025] In this invention, unless otherwise explicitly defined, the terms "setting," "installing," and "connecting" should be interpreted broadly. For example, they can refer to a direct connection or an indirect connection through an intermediate medium; a fixed connection, a detachable connection, or an integrally formed connection; a mechanical connection, an electrical connection, or a connection capable of mutual communication; or the internal connection of two components or the interaction between two components. Those skilled in the art can reasonably determine the specific meaning of the above terms in this invention based on the specific content of the technical solution.

[0026] Reference Figure 1 As shown, the preparation method of gradient porous carbon paper substrate based on the synergistic regulation of impregnation-doping includes: (1) Preparation of impregnation solution: Mix the resin and conductive carbon black in a predetermined ratio and disperse them evenly for later use; (2) First layer of carbon fiber paper impregnation: The carbon fiber paper is impregnated in the impregnation solution and the amount of adhesive W1 is controlled by the liquid rolling roller. Then it is dried for later use to obtain the first layer of impregnated paper. (3) Impregnation of the second layer of carbon fiber paper: The carbon fiber paper is immersed in the impregnation solution and the amount of adhesive W2 is controlled by the sizing roller. Then it is dried for later use to obtain the second layer of impregnated paper. (4) Impregnation of the third layer of carbon fiber paper: The carbon fiber paper is immersed in the impregnation solution and the amount of glue applied is controlled by the sizing roller W3. Then it is dried for later use to obtain the third layer of impregnated paper. (5) The nth (n is a positive integer) layer of carbon fiber paper is impregnated with the resin solution. The carbon fiber paper is impregnated in the resin solution and the amount of resin applied is controlled by the liquid roller. Then it is dried for later use to obtain the nth layer of impregnated paper. (6) Composite hot pressing curing: The first to n layers of impregnated paper are arranged in order from small to large, and composite hot pressing is performed using a hot press. After heat curing, the paper is taken out to obtain a cured paper with gradient pores. (7) Heat-treat the cured paper with gradient pores. After the heat treatment is completed, a carbon paper substrate with gradient pores is obtained.

[0027] Specifically, the resin is one or more of alcohol-soluble phenolic resin, oil-soluble phenolic resin, and modified phenolic resin; the conductive carbon black is at least one of 5-40 wt% XC-72 carbon powder, 5-50 wt% carbon nanotubes, and 5-50 wt% flake graphite, and the ratio of the resin to the conductive carbon black is configured such that the resin ratio is 50%-90% and the corresponding conductive carbon black ratio is 50%-10%.

[0028] Specifically, in steps (2) to (5), the surface density of the carbon fiber paper is 10 g / m³. 2 -50g / m 2 The thickness is 100μm-500μm; the amount of adhesive applied W1 is 20-50%, the amount of adhesive applied W2 is 50%-80%, the amount of adhesive applied W3 is 80%-110%, and the amount of adhesive applied Wn is 30% of the increase in the amount of the previous layer, where n is 3-6.

[0029] Specifically, in steps (2) to (5), the drying temperature is 80-120℃ and the pressure of the rolling mill is 0.1MPa-0.5MPa.

[0030] Specifically, in step (6), the temperature of the composite hot pressing is 150℃-200℃, the time is 3min-10min, and the pressure is 0.2MPa-0.7MPa.

[0031] Specifically, the heat treatment in step (7) is performed at a temperature of 1800℃-2800℃ for a time of 10min-30min.

[0032] This invention provides a gradient porous carbon paper substrate based on the synergistic regulation of impregnation and doping, which is prepared by the aforementioned method for preparing a gradient porous carbon paper substrate based on the synergistic regulation of impregnation and doping.

[0033] Specifically, the gradient porous carbon paper substrate includes at least two sub-layers, with the porosity between adjacent sub-layers varying by a gradient of not less than 5%, and arranged sequentially from the microporous layer on the catalyst layer side to the macroporous layer on the bipolar plate side.

[0034] Specifically, the gradient porous carbon paper substrate has a continuously varying pore size distribution along the thickness direction, the pore size range of the gradient pores is 0-100μm, and the pore size increases by not less than 0.5μm for every 10μm increase in the thickness direction.

[0035] Example 1 Preparation of impregnation solution: Mix phenolic resin and XC-72 toner in a 1:1 ratio and disperse evenly for later use; cut multiple sheets with a surface density of 10g / m². 2 Carbon fiber paper is prepared for use. The first layer of carbon fiber paper is impregnated with resin: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 20% using a padding roller, then dried to obtain the first layer of impregnated paper; the second layer of carbon fiber paper is impregnated with resin: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 50% using a padding roller, then dried to obtain the second layer of impregnated paper; the third layer of carbon fiber paper is impregnated with resin: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 80% using a padding roller, then dried to obtain the third layer of impregnated paper; the fourth layer of carbon fiber paper is impregnated with resin: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 110% using a padding roller, then dried to obtain the fourth layer of impregnated paper; the drying temperature is 80℃. Composite hot-press curing: The first to fourth layers of impregnated paper are arranged in ascending order of size and composite hot-pressed for 10 minutes at 150°C and 0.2 MPa using a hot press. After heat curing, the paper is removed to obtain a cured paper with gradient pores. The cured paper with gradient pores is then subjected to high-temperature heat treatment at 1800°C for 30 minutes. After heat treatment, a carbon paper substrate with gradient pores is obtained.

[0036] Example 2 Preparation of impregnation solution: Mix phenolic resin and XC-72 toner in a 75%:25% ratio and disperse evenly for later use; cut multiple sheets with a surface density of 30g / m². 2Carbon fiber paper is prepared for use. The first layer of carbon fiber paper is impregnated with resin: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 35% using a padding roller, then dried to obtain the first layer of impregnated paper; the second layer of carbon fiber paper is impregnated with resin: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 65% using a padding roller, then dried to obtain the second layer of impregnated paper; the third layer of carbon fiber paper is impregnated with resin: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 95% using a padding roller, then dried to obtain the third layer of impregnated paper; the fourth layer of carbon fiber paper is impregnated with resin: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 125% using a padding roller, then dried to obtain the fourth layer of impregnated paper; the drying temperature is 100℃. Composite hot-press curing: The first to fourth layers of impregnated paper are arranged in ascending order of size and composite hot-pressed for 6 minutes at 175℃ and 0.5MPa using a hot press. After heat curing, the paper is removed to obtain a cured paper with gradient pores. The cured paper with gradient pores is then subjected to high-temperature heat treatment at 2400℃ for 20 minutes. After heat treatment, a carbon paper substrate with gradient pores is obtained.

[0037] Example 3 Preparation of impregnation solution: Mix phenolic resin and XC-72 toner in a 90%:10% ratio and disperse evenly for later use; cut multiple sheets with a surface density of 10g / m². 2 Carbon fiber paper is prepared for use. The process involves the following steps: First layer of carbon fiber paper impregnation: The carbon fiber paper is immersed in the impregnation solution, and the amount of adhesive applied is controlled at 50% using a padding roller. It is then dried to obtain the first layer of impregnated paper. Second layer of carbon fiber paper impregnation: The carbon fiber paper is immersed in the impregnation solution, and the amount of adhesive applied is controlled at 80% using a padding roller. It is then dried to obtain the second layer of impregnated paper. Third layer of carbon fiber paper impregnation: The carbon fiber paper is immersed in the impregnation solution, and the amount of adhesive applied is controlled at 110% using a padding roller. It is then dried to obtain the third layer of impregnated paper. Fourth layer of carbon fiber paper impregnation: The carbon fiber paper is immersed in the impregnation solution, and the amount of adhesive applied is controlled at 140% using a padding roller. It is then dried to obtain the fourth layer of impregnated paper. The drying temperature is 120℃. Composite hot-press curing: The first to fourth layers of impregnated paper are arranged in ascending order of size and composite hot-pressed for 3 minutes at 200℃ and 0.7MPa using a hot press. After heat curing, the paper is removed to obtain a cured paper with gradient pores. The cured paper with gradient pores is then subjected to high-temperature heat treatment at 2800℃ for 10 minutes. After heat treatment, a carbon paper substrate with gradient pores is obtained.

[0038] Comparative Example 1 Preparation of impregnation solution: Mix phenolic resin and XC-72 toner in a 1:1 ratio and disperse evenly for later use; cut multiple sheets with a surface density of 10g / m². 2Carbon fiber paper is prepared for use. The carbon fiber paper is immersed in the impregnation solution and the amount of adhesive applied is controlled to 200% using a squeegee roller. After drying, the impregnated paper is prepared for use. The impregnated paper is then subjected to hot pressing for 10 minutes at a temperature of 150°C and a pressure of 0.2 MPa. After heat curing, the paper is removed to obtain cured paper. The cured paper with gradient pores is then subjected to high-temperature heat treatment at a temperature of 1800°C for 30 minutes. After the heat treatment is completed, a carbon paper substrate is obtained.

[0039] Comparative Example 2 Phenolic resin was used directly as the impregnation solution, and multiple sheets were cut with a surface density of 10 g / m². 2 Carbon fiber paper is prepared for use. The first layer of carbon fiber paper is impregnated with resin: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 20% using a padding roller, then dried to obtain the first layer of impregnated paper; the second layer of carbon fiber paper is impregnated with resin: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 50% using a padding roller, then dried to obtain the second layer of impregnated paper; the third layer of carbon fiber paper is impregnated with resin: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 80% using a padding roller, then dried to obtain the third layer of impregnated paper; the fourth layer of carbon fiber paper is impregnated with resin: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 110% using a padding roller, then dried to obtain the fourth layer of impregnated paper; the drying temperature is 80℃. Composite hot-press curing: The first to fourth layers of impregnated paper are arranged in ascending order of size and composite hot-pressed for 10 minutes at 150°C and 0.2 MPa using a hot press. After heat curing, the paper is removed to obtain a cured paper with gradient pores. The cured paper with gradient pores is then subjected to high-temperature heat treatment at 1800°C for 30 minutes. After heat treatment, a carbon paper substrate with gradient pores is obtained.

[0040] Comparative Example 3 Preparation of impregnation solution: Mix phenolic resin and XC-72 toner in a 1:1 ratio and disperse evenly for later use; cut multiple sheets with a surface density of 10g / m². 2The carbon fiber paper is prepared for use. The first layer of carbon fiber paper is impregnated with the resin solution: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 20% using a padding roller, then dried to obtain the first layer of impregnated paper; the second layer of carbon fiber paper is impregnated with the resin solution: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 50% using a padding roller, then dried to obtain the second layer of impregnated paper; the third layer of carbon fiber paper is impregnated with the resin solution: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 80% using a padding roller, then dried to obtain the third layer of impregnated paper; the fourth layer of carbon fiber paper is impregnated with the resin solution: the carbon fiber paper is immersed in the resin solution, and the resin application is controlled at 80% using a padding roller, then dried to obtain the third layer of impregnated paper; The adhesive application rate is 110%, followed by drying to obtain the fourth layer of impregnated paper; the fifth layer of carbon fiber paper is impregnated with the adhesive solution, and the adhesive application rate is controlled at 140% using a padding roller, followed by drying to obtain the fifth layer of impregnated paper; the sixth layer of carbon fiber paper is impregnated with the adhesive solution, and the adhesive application rate is controlled at 170% using a padding roller, followed by drying to obtain the sixth layer of impregnated paper; the seventh layer of carbon fiber paper is impregnated with the adhesive solution, and the adhesive application rate is controlled at 200% using a padding roller, followed by drying to obtain the seventh layer of impregnated paper; the drying temperature is 80℃. Composite hot-press curing: The first to seventh layers of impregnated paper are arranged in ascending order of size and composite hot-pressed for 10 minutes at 150°C and 0.2 MPa using a hot press. After heat curing, the paper is removed to obtain a cured paper with gradient pores. The cured paper with gradient pores is then subjected to high-temperature heat treatment at 1800°C for 30 minutes. After heat treatment, a carbon paper substrate with gradient pores is obtained.

[0041] Comparative Example 4 Preparation of impregnation solution: Mix phenolic resin and XC-72 toner in a 1:1 ratio and disperse evenly for later use; cut multiple sheets with a surface density of 10g / m². 2Carbon fiber paper is prepared for use. The process involves the following steps: First layer of carbon fiber paper impregnation: The carbon fiber paper is immersed in the impregnation solution, and the amount of adhesive applied is controlled at 50% using a padding roller. It is then dried to obtain the first layer of impregnated paper. Second layer of carbon fiber paper impregnation: The carbon fiber paper is immersed in the impregnation solution, and the amount of adhesive applied is controlled at 20% using a padding roller. It is then dried to obtain the second layer of impregnated paper. Third layer of carbon fiber paper impregnation: The carbon fiber paper is immersed in the impregnation solution, and the amount of adhesive applied is controlled at 80% using a padding roller. It is then dried to obtain the third layer of impregnated paper. Fourth layer of carbon fiber paper impregnation: The carbon fiber paper is immersed in the impregnation solution, and the amount of adhesive applied is controlled at 30% using a padding roller. It is then dried to obtain the fourth layer of impregnated paper. The drying temperature is 80℃. Composite hot-press curing: The first to fourth layers of impregnated paper are arranged in ascending order of size and composite hot-pressed for 10 minutes at 150°C and 0.2 MPa using a hot press. After heat curing, the paper is removed to obtain a cured paper with gradient pores. The cured paper with gradient pores is then subjected to high-temperature heat treatment at 1800°C for 30 minutes. After heat treatment, a carbon paper substrate with gradient pores is obtained.

[0042] The porosity of the carbon paper was tested, and it was then prepared into a GDL for battery performance testing. The results show that the embodiment improved both the ohmic polarization region and the mass transfer polarization region, and exhibited superior gas-liquid transport capability, ultimately achieving multi-objective optimization. The data are as follows: Table 1 Sample porosity

[0043] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing gradient porous carbon paper substrate based on synergistic regulation of impregnation-doping, characterized in that, include: (1) Preparation of impregnation solution: Mix the resin and conductive carbon black in a predetermined ratio and disperse them evenly for later use; (2) First layer of carbon fiber paper impregnation: The carbon fiber paper is impregnated in the impregnation solution and the amount of adhesive W1 is controlled by the liquid rolling roller. Then it is dried for later use to obtain the first layer of impregnated paper. (3) Impregnation of the second layer of carbon fiber paper: The carbon fiber paper is immersed in the impregnation solution and the amount of adhesive W2 is controlled by the sizing roller. Then it is dried for later use to obtain the second layer of impregnated paper. (4) Impregnation of the third layer of carbon fiber paper: The carbon fiber paper is immersed in the impregnation solution and the amount of glue applied is controlled by the sizing roller W3. Then it is dried for later use to obtain the third layer of impregnated paper. (5) Impregnation of the nth layer of carbon fiber paper with impregnation solution: The carbon fiber paper is impregnated in the impregnation solution and the amount of adhesive Wn is controlled by the liquid rolling roller. Then it is dried for later use to obtain the nth layer of impregnated paper. (6) Composite hot pressing curing: The first to n layers of impregnated paper are arranged in order from small to large, and composite hot pressing is performed using a hot press. After heat curing, the paper is taken out to obtain a cured paper with gradient pores. (7) Heat-treat the cured paper with gradient pores. After heat treatment, carbon paper substrate with gradient pores is obtained. In steps (2) to (5), the surface density of the carbon fiber paper is 10 g / m³. 2 -50g / m 2 The thickness is 100μm-500μm; the amount of adhesive applied W1 is 20-50%, the amount of adhesive applied W2 is 50%-80%, the amount of adhesive applied W3 is 80%-110%, and the amount of adhesive applied Wn is 30% of the increase in the amount of the previous layer, where n is 3-6.

2. The method for preparing gradient porous carbon paper substrate based on synergistic control of impregnation and doping according to claim 1, characterized in that, The resin is one or more of alcohol-soluble phenolic resin, oil-soluble phenolic resin, and modified phenolic resin; the conductive carbon black is at least one of 5-40 wt% XC-72 carbon powder, 5-50 wt% carbon nanotubes, and 5-50 wt% flake graphite; the ratio of the resin to the conductive carbon black is configured such that the resin ratio is 50%-90% and the corresponding conductive carbon black ratio is 50%-10%.

3. The method for preparing gradient porous carbon paper substrate based on synergistic control of impregnation and doping according to claim 1, characterized in that, In steps (2) to (5), the drying temperature is 80-120℃ and the pressure of the rolling mill is 0.1MPa-0.5MPa.

4. The method for preparing gradient porous carbon paper substrate based on impregnation-doping synergistic regulation according to claim 1, characterized in that, In step (6), the temperature of the composite hot pressing is 150℃-200℃, the time is 3min-10min, and the pressure is 0.2MPa-0.7MPa.

5. The method for preparing gradient porous carbon paper substrate based on synergistic regulation of impregnation-doping according to claim 1, characterized in that, The heat treatment in step (7) is performed at a temperature of 1800℃-2800℃ for a time of 10min-30min.

6. A gradient-porous carbon paper substrate based on synergistic regulation of impregnation and doping, characterized in that, It is prepared according to the preparation method of gradient porous carbon paper substrate based on impregnation-doping synergistic regulation as described in any one of claims 1-5.

7. The gradient porosity carbon paper substrate based on impregnation-doping synergistic regulation according to claim 6, characterized in that, The gradient porous carbon paper substrate includes at least two sub-layers, with the porosity between adjacent sub-layers varying by a gradient of not less than 5%, and arranged sequentially from the microporous layer on the catalyst side to the macroporous layer on the bipolar plate side.

8. The gradient porosity carbon paper substrate based on impregnation-doping synergistic regulation according to claim 7, characterized in that, The gradient porous carbon paper substrate has a continuously varying pore size distribution along the thickness direction. The pore size range of the gradient pores is 0-100μm, and the pore size increases by no less than 0.5μm for every 10μm increase in the thickness direction.

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