High-air-permeability, bend-resistant carbon fiber paper, and preparation method and application thereof

Abstract

The application belongs to the technical field of fuel cell gas diffusion layer, and specifically discloses a high-air-permeability and bending-resistant carbon fiber paper as well as a preparation method and application thereof, which comprises the following steps: (1) carbon fibers, bonding fibers and a dispersing agent are adopted to obtain carbon fiber raw paper through a wet forming process; (2) an alcohol-soluble resin is dissolved in ethanol to prepare a stable ethanol-resin solution, and then the ethanol-resin solution is poured into water to obtain a suspension after uniform stirring; (3) the carbon fiber raw paper is soaked in the suspension, and after being taken out, the soaked paper is subjected to pre-curing treatment to obtain a resin-impregnated paper; and (4) the resin-impregnated paper is subjected to carbonization treatment in a protective atmosphere to obtain the high-air-permeability and bending-resistant carbon fiber paper. The carbon fiber paper has a tensile modulus of 2000 MPa, an air permeability of about 3250 mm / s, an electrical conductivity of about 40 s / cm, and can withstand direct bending of 90 degrees for dozens of times, and has good durability and high air permeability; and the method has simple process and low cost.

Description

Technical Field

[0001] This invention relates to the field of fuel cell gas diffusion layer technology, and specifically to a method for preparing high-porosity, bend-resistant carbon paper. Background Technology

[0002] Fuel cells, unaffected by the Carnot cycle, represent a crucial direction for new energy development. Carbon paper, as a vital component of the gas diffusion layer, participates in water vapor management and current transmission, thus requiring high levels of permeability, conductivity, and durability. Currently, the industrial production of carbon paper has a low degree of domestic self-sufficiency, resulting in significant deficiencies in toughness and durability. Existing literature primarily describes the preparation of carbon paper using a wet molding process—resin impregnation—hot pressing curing—high-temperature carbonization. In this process, the resin, after high-temperature carbonization, bonds the carbon fibers into a single unit in the form of resin carbon. However, resin carbon exhibits considerable brittleness, making the carbon paper prone to direct fracture under external forces. Furthermore, after hot pressing carbonization, the resin is distributed in a sheet-like form within the carbon paper network structure, severely reducing the porosity of the carbon paper.

[0003] Invention patent CN108914681A discloses a method for preparing carbon fiber paper: polyacrylonitrile-based carbon fiber and mesophase pitch-based carbon fiber are mixed in a certain proportion, impregnated with a thermosetting phenolic resin-ethanol solution, and then carbonized and graphitized to obtain carbon fiber paper. Although the obtained carbon fiber paper has excellent electrical and thermal conductivity, the preparation process is relatively complex, and the carbon fiber paper is brittle and easily breaks under external force.

[0004] Invention patent CN113066995A discloses a PEM fuel cell, high-toughness porous carbon paper, and its preparation method. The method involves carbon deposition on pretreated metal fibers, followed by preparation of a porous carbon paper preform with polyvinyl acetal, impregnation with an N-methylpyrrolidone solution containing bisphenol A phthalonitrile, and high-temperature carbonization to obtain the high-toughness porous carbon paper. This preparation method is relatively complex, and the addition of metal fibers results in a relatively high weight of the carbon paper. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to improve the durability and breathability of carbon paper, avoiding problems such as easy breakage and low porosity caused by resin-impregnated carbon paper. This invention employs a resin impregnation method to achieve good bonding between carbon fibers, while simultaneously giving it good bending resistance and high breathability.

[0006] Through testing, the carbon fiber paper produced by this invention has an air permeability of 3250 mm / s and can withstand dozens of direct 90° bends without breaking.

[0007] To achieve the above-mentioned technical objectives, the present invention is implemented through the following technical solutions.

[0008] A method for preparing highly air-permeable and bend-resistant carbon fiber paper includes the following steps:

[0009] (1) Carbon fiber base paper is obtained by wet molding process of carbon fiber, bonding fiber and dispersant;

[0010] (2) Dissolve the alcohol-soluble resin in ethanol to prepare a stable ethanol-resin solution, then pour the ethanol-resin solution into water and stir evenly to obtain a suspension.

[0011] (3) The carbon fiber base paper is soaked in the suspension, and then pre-cured to obtain the impregnated paper.

[0012] (4) The impregnated paper is carbonized under a protective atmosphere to obtain carbon fiber paper with high air permeability and bending resistance.

[0013] Preferably, the carbon fiber in step (1) is one or more of PAN-based and pitch-based carbon fibers, and has a length of 2 to 12 mm.

[0014] Preferably, the alcohol-soluble resin in step (2) is a resin with a high carbon residue rate.

[0015] Preferably, the alcohol-soluble resin is one or more of furan resin, phenolic resin, and asphalt resin.

[0016] Preferably, the concentration of the ethanol-resin solution is 5% to 60 wt%, and the concentration of the alcohol-soluble resin in the suspension is 0.2% to 20%.

[0017] Preferably, the concentration of the ethanol-resin solution is 5% to 10 wt%, and the concentration of the alcohol-soluble resin in the suspension is 0.5% to 3.0%.

[0018] Preferably, the pre-curing conditions in step (3) are a temperature of 60-150℃ and a holding time of 30-120min; the carbonization conditions in step (4) are a temperature of 900-1400℃, a heating rate of 2-15℃ / min, and a carbonization treatment time of 30-180min.

[0019] Preferably, the soaking time in step (4) is 30 to 90 seconds. After soaking, the excess soaking liquid is scraped off and the product is dried. The product is then turned over every 5 to 30 minutes.

[0020] The high-permeability and bend-resistant carbon fiber paper prepared by the above method can be used in the gas diffusion layer of fuel cells.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] (1) The carbon fiber paper prepared by this invention has a simple process, requires only a small amount of resin as a binder, has a low cost, and is easy to promote industrialization.

[0023] (2) The carbon fiber paper obtained by the method of the present invention has high air permeability, which facilitates the transmission of water vapor in the gas diffusion layer.

[0024] (3) The carbon fiber paper obtained by the method of the present invention has good bending resistance, can withstand 90° bending without direct breakage, and has good durability. Attached Figure Description

[0025] Figure 1 This is a photograph of the high-permeability, bend-resistant carbon fiber paper prepared in Example 1.

[0026] Figure 2 This is a SEM image of the high-permeability, bend-resistant carbon fiber paper prepared in Example 1.

[0027] Figure 3 The image shows the cross-sectional morphology of the high-permeability, bend-resistant carbon fiber paper prepared in Example 1 using SEM.

[0028] Figure 4 This is a SEM image of the high-permeability, bend-resistant carbon fiber paper prepared in Example 2.

[0029] Figure 5 The image shows a SEM image of the carbon fiber paper prepared in Comparative Example 1.

[0030] Figure 6 The image shows a SEM image of the carbon fiber paper prepared in Comparative Example 2. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto. For process parameters not specifically noted, conventional techniques can be referred to.

[0032] Example 1

[0033] (1) 6.28g of carbon fiber, 0.05% polyethylene oxide and 10% polyvinyl alcohol fiber were dispersed in a disintegrator and carbon fiber base paper was obtained by wet molding.

[0034] (2) Dissolve 12.64g of phenolic resin in 200ml of anhydrous ethanol to form an ethanol-resin solution with a concentration of 6.32%. Take 40ml of the ethanol-resin solution and inject it into 200ml of water. Stir well.

[0035] (3) After soaking the carbon fiber base paper in the impregnation solution in step (2) for 30 seconds, take it out, scrape off the excess impregnation solution, lay it flat until dry, and turn it over every 15 minutes.

[0036] (4) Place the dipped paper in a high-temperature oven and keep it at 80℃ for 30 minutes, 100℃ for 30 minutes, and 140℃ for 60 minutes respectively for pre-curing treatment.

[0037] (5) The pre-cured paper in step (4) is carbonized in N2 atmosphere, heated to 1400℃ at a heating rate of 10℃ / min, and kept at the temperature for 60min to obtain carbon fiber paper.

[0038] Example 2

[0039] (1) 6.28g of carbon fiber, 0.05% polyethylene oxide and 10% polyvinyl alcohol fiber were dispersed in a disintegrator and carbon fiber base paper was obtained by wet molding.

[0040] (2) Dissolve 18.97g of furan resin in 200ml of anhydrous ethanol to form an ethanol-resin solution with a concentration of 9.5%. Take 50ml of the ethanol-resin solution and inject it into 200ml of water, and stir well.

[0041] (3) After immersing the carbon fiber base paper in the impregnation solution in step (2) for 60 seconds, remove it, scrape off the excess impregnation solution, lay it flat until dry, and turn it over every 20 minutes.

[0042] (4) Place the dipped paper in a high-temperature oven and keep it at 80℃ for 60 min and 140℃ for 60 min respectively for pre-curing treatment;

[0043] (5) The pre-cured paper in step (4) is carbonized in N2 atmosphere, heated to 1400℃ at a heating rate of 10℃ / min, and kept at the temperature for 60min to obtain carbon fiber paper.

[0044] Example 3

[0045] (1) 6.28g of carbon fiber, 0.05% polyethylene oxide and 10% polyvinyl alcohol fiber were dispersed in a disintegrator and carbon fiber base paper was obtained by wet molding.

[0046] (2) Dissolve 18.97g of furan resin in 200ml of anhydrous ethanol to form a 9.5% ethanol-resin solution. Take 20ml of the ethanol-resin solution and inject it into 200ml of water. Stir well.

[0047] (3) After immersing the carbon fiber base paper in the impregnation solution in step (2) for 60 seconds, remove it, scrape off the excess impregnation solution, lay it flat until dry, and turn it over every 20 minutes.

[0048] (4) Place the dipped paper in a high-temperature oven and keep it at 80℃ for 60 min and 140℃ for 60 min respectively for pre-curing treatment;

[0049] (5) The pre-cured paper in step (4) is carbonized in N2 atmosphere, heated to 1400℃ at a heating rate of 10℃ / min, and kept at the temperature for 60min to obtain carbon fiber paper.

[0050] Example 4

[0051] (1) 6.28g of carbon fiber, 0.05% polyethylene oxide and 10% polyvinyl alcohol fiber were dispersed in a disintegrator and carbon fiber base paper was obtained by wet molding.

[0052] (2) Dissolve 18.97g of phenolic resin in 200ml of anhydrous ethanol to form a 9.5% ethanol-resin solution. Take 40ml of the ethanol-resin solution and inject it into 200ml of water. Stir well.

[0053] (3) After immersing the carbon fiber base paper in the impregnation solution in step (2) for 60 seconds, remove it, scrape off the excess impregnation solution, lay it flat until dry, and turn it over every 20 minutes.

[0054] (4) Place the dipped paper in a high-temperature oven and keep it at 80℃ for 60 min and 140℃ for 60 min respectively for pre-curing treatment;

[0055] (5) The pre-cured paper in step (4) is carbonized in N2 atmosphere, heated to 1300℃ at a heating rate of 5℃ / min, and kept at that temperature for 90min to obtain carbon fiber paper.

[0056] Comparative Example 1

[0057] The difference between this embodiment and Embodiment 1 is that the carbon fiber base paper was directly impregnated in a 6.32% (w / w) ethanol-resin solution. The air permeability, electrical conductivity, and folding endurance of the resulting carbon fiber paper are shown in Table 1.

[0058] Comparative Example 2

[0059] The difference between this embodiment and Embodiment 3 is that the carbon fiber base paper was directly impregnated in a 9.5% (w / w) ethanol-resin solution. The air permeability, electrical conductivity, and folding endurance of the resulting carbon fiber paper are shown in Table 1.

[0060] As shown in Table 1, the carbon fiber paper obtained in Examples 1-4 exhibits excellent air permeability and bending resistance. In Comparative Examples 1 and 2, the ethanol-resin solutions did not disperse in water to form a suspension. After carbonization, the resin carbon was mostly distributed in a sheet-like form within the carbon fiber mesh structure, resulting in poor air permeability and low bending resistance. Furthermore, due to… Figure 5 , 6 It is evident that the carbon paper in Comparative Examples 1 and 2 has relatively low porosity; while the porosity of the carbon paper of this invention is significantly improved. Figure 2-4 ).

[0061] Table 1

[0062]

[0063]

[0064] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a highly air-permeable and bend-resistant carbon fiber paper, characterized in that, Includes the following steps: (1) Carbon fiber base paper is obtained by wet molding process of carbon fiber, bonding fiber and dispersant; (2) An ethanol-resin solution is prepared by dissolving the alcohol-soluble resin in ethanol, and then the ethanol-resin solution is poured into water and stirred evenly to obtain a suspension; the concentration of the ethanol-resin solution is 5%~10 wt%, and the concentration of the alcohol-soluble resin in the suspension is 0.5%~3.0%; the alcohol-soluble resin is one or two of furan resin and phenolic resin. (3) The carbon fiber base paper is immersed in the suspension, and then pre-cured to obtain the impregnated paper. (4) Carbonize the impregnated paper under a protective atmosphere to obtain carbon fiber paper with high air permeability and bending resistance.

2. The preparation method according to claim 1, characterized in that, The carbon fiber mentioned in step (1) is one or both of PAN-based carbon fiber and pitch-based carbon fiber, with a length of 2~12mm.

3. The preparation method according to claim 1 or 2, characterized in that, The pre-curing conditions in step (3) are a temperature of 60~150℃ and a holding time of 30~120min; the carbonization conditions in step (4) are a temperature of 900~1400℃, a heating rate of 2~15℃ / min, and a carbonization treatment time of 30~180min.

4. The preparation method according to claim 3, characterized in that, In step (3), the soaking time is 30~90 s. After soaking, scrape off the excess soaking liquid and dry. Turn over every 5~30 minutes.

5. The high-permeability, fold-resistant carbon fiber paper prepared by the preparation method according to any one of claims 1 to 4.

6. The application of the high-permeability, bend-resistant carbon fiber paper as described in claim 5 in the gas diffusion layer of a fuel cell.

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