Carbon paper for gas diffusion layer with water-gas management function and preparation method of carbon paper

Abstract

The invention belongs to the technical field of fuel cells, and particularly relates to carbon paper for a gas diffusion layer with a water-gas management function and a preparation method of the carbon paper. The carbon paper for the gas diffusion layer comprises at least three alternately stacked carbon layer structures, odd layers are macroporous carbon layers, and the macroporous carbon layers are formed by dipping carbon fiber base paper in a mixed solution of resin and a conductive material and drying the carbon fiber base paper; the even-numbered layers are small-hole carbon layers, and the small-hole carbon layers comprise resin and conductive materials and are coated on the surfaces of the odd-numbered layers; the odd-numbered layers and the even-numbered layers are compounded through a hot-pressing process to form a composite material; the composite material is subjected to high-temperature heat treatment to form a carbon paper A conductive network is formed in the carbon paper, the carbon paper with higher conductivity is prepared, part of the conductive material is filled in the carbon paper to build a microporous structure, the low-gram-weight base paper forms a macroporous structure, and the conductive material and the resin are mixed to form a microporous structure, so that the water and gas management capability is favorably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to carbon paper for a gas diffusion layer with a water vapor management function and a preparation method thereof. Background Art

[0002] As a highly efficient energy conversion device, fuel cells have broad application prospects in the energy field. Among them, the gas diffusion layer plays a vital role in fuel cells and needs to have good air permeability, conductivity and water vapor management capabilities. Carbon paper is a commonly used gas diffusion layer material, and its performance is directly related to the performance and life of fuel cells.

[0003] Under the existing technology, the carbon paper prepared by the traditional process of impregnating base paper with resin solution, curing, carbonization, etc. has problems such as single pore structure, insufficient conductivity, and limited water vapor management ability. Patent CN118704265A discloses a method for preparing carbon fiber paper, which adopts the traditional impregnation treatment method. It is difficult to ensure the uniformity of resin impregnation. The pore structure of carbon paper prepared by this method is not easy to accurately control, and there are certain limitations on the water vapor management ability. Patent CN117913308A discloses a fuel cell pore size multi-layer gradient gas diffusion layer and its preparation method. The method used in this patent to prepare multi-layer gradient operation is more complicated. Although the water vapor management ability is improved, the pore size control between the multiple layers is more difficult and the operation is more complicated.

[0004] Good water vapor management capabilities ensure that the reaction gas is evenly diffused in the carbon paper, so that the electrochemical reaction of the fuel cell can be carried out efficiently, maintain a good reaction environment inside the fuel cell, and improve the stability and durability of the battery. The current fuel cell carbon paper preparation technology has its own problems in different patent methods, such as structural damage, poor uniformity, high cost and introduction of impurities, which directly or indirectly affect the water vapor management ability of the carbon paper. Developing carbon paper preparation technology with excellent water vapor management capabilities is one of the key directions for the future development of fuel cells. This requires comprehensive consideration of multiple factors such as material selection, preparation process optimization and structural design to overcome the shortcomings of existing technologies and promote the further development of fuel cell technology. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a carbon paper for a gas diffusion layer with a water vapor management function and a preparation method thereof. The present invention forms a conductive network inside the carbon paper to prepare a carbon paper with stronger conductivity, partially fills the inside with conductive materials to form a microporous structure, forms a macroporous structure with low-weight base paper, and mixes conductive materials and resins to form a microporous structure, which helps to improve the water vapor management capability.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the embodiment of the present invention is:

[0007] In the first aspect, an embodiment of the present invention provides a carbon paper for a gas diffusion layer with a water vapor management function, comprising at least three alternately stacked carbon layer structures, wherein the odd-numbered layers are macroporous carbon layers, which are formed by impregnating carbon fiber base paper in a mixture of resin and conductive material and drying; the even-numbered layers are microporous carbon layers, which include resin and conductive material and are coated on the surface of the odd-numbered layers; the odd-numbered layers and the even-numbered layers are compounded to form a composite material through a hot pressing process, and the composite material is subjected to high-temperature heat treatment to form a carbon paper finished product.

[0008] Furthermore, the thickness of a single odd-numbered layer is 40 to 100 μm, the porosity is 65% to 85%, and the pore size is 10 to 50 μm; the odd-numbered layer serves as the main supporting structure, providing macroporous channels to dominate water vapor transmission.

[0009] Furthermore, the thickness of a single even-numbered layer is 10-50 μm, the porosity is 40%-60%, and the pore size is 0.5-20 μm; the even-numbered layers form small pore channels to assist water vapor transmission and enhance the overall conductivity of the carbon paper.

[0010] Furthermore, the average pore size of the macroporous carbon layer is greater than the average pore size of the microporous carbon layer, and the porosity of the macroporous carbon layer is greater than the porosity of the microporous carbon layer; wherein the pore size and porosity are achieved by regulating the mass ratio of the conductive material to the resin and the loading of the mixed solution after impregnation.

[0011] In a second aspect, an embodiment of the present invention provides a method for preparing the carbon paper for a gas diffusion layer having a water vapor management function as described in the first aspect, comprising the following steps:

[0012] Step S1, preparation of odd-numbered macroporous carbon layers: impregnating carbon fiber base paper in a uniform mixture of resin and conductive material, and drying the impregnated carbon fiber base paper at 65-95° C. for 10-60 min to obtain odd-numbered macroporous carbon layers;

[0013] Step S2, preparation of an even-numbered small-porous carbon layer: uniformly coating a uniform mixture of resin and conductive material on the surface of an odd-numbered macroporous carbon layer to form an even-numbered small-porous carbon layer;

[0014] Step S3, alternately stacking odd-numbered layers and even-numbered layers: repeating steps S1 and S2 to alternately stack odd-numbered layers and even-numbered layers to a target number of layers, and drying at 65-95° C. to obtain a composite laminate structure;

[0015] Step S4, composite hot pressing: subjecting the laminated structure obtained in step S3 to composite hot pressing curing treatment at 80-300° C. and 0.1-30 MPa for 1-30 min;

[0016] Step S5, high temperature heat treatment: subjecting the composite material after the composite hot pressing and curing in step S4 to high temperature heat treatment to obtain carbon paper for gas diffusion layer with good water vapor management capability.

[0017] Furthermore, the weight of the carbon fiber base paper in step S1 is 10 to 40 g / m 2 After impregnation and drying, the resin content in the carbon fiber base paper is 10% to 300% of the base paper weight.

[0018] Furthermore, in step S1, the mass ratio of the resin to the conductive material is 100-10:0-90;

[0019] The mass ratio of the resin to the conductive material in step S2 is 90-10:10-90.

[0020] Furthermore, the resin in step S1 and step S2 is phenolic resin and / or epoxy resin, and the conductive material is a combination of one or more of graphite powder, carbon nanotubes and conductive carbon black.

[0021] Furthermore, in step S4, the composite hot pressing method adopts a hot pressing method including flat plate hot pressing and multi-roller hot pressing.

[0022] Furthermore, in step S5, the conditions of the high temperature heat treatment are: carbonization temperature 1000-1500° C., insulation time 0.1-2 hours, graphitization temperature 2000-2800° C., insulation time 0.1-2 hours.

[0023] The technical solution provided by the embodiment of the present invention has the following beneficial effects:

[0024] 1. The carbon paper for gas diffusion layer of the present invention has a small-pore carbon layer composed of a conductive material and a resin pressed between the macroporous carbon paper layer structure. After curing, the conductive material layer forms a conductive network inside the carbon paper, which significantly improves the conductivity of the carbon paper compared to the prior art and reduces the energy loss in the transmission process during the operation of the fuel cell.

[0025] 2. The internal pore structure of carbon paper prepared by the prior art is consistent. The small pore structure and the macropore structure of the present invention work together. The macropore structure formed by the low-weight base paper provides a good channel for gas transmission, which is conducive to the rapid diffusion of gas and improves the gas transmission efficiency; and the conductive material is mixed with the resin and filled to form a small pore structure, which cooperates with the macropore structure to construct a multi-level pore system. On the one hand, this structure can increase the gas storage capacity and ensure sufficient gas supply under different working conditions; on the other hand, it helps to achieve good water and gas management, can timely discharge the water generated during the reaction, prevent the occurrence of flooding, maintain the good working condition of the electrode, and improve the stability and reliability of the fuel cell.

[0026] 3. The preparation method of the present invention combines materials and processes with different characteristics, giving full play to the advantages of different materials. The addition of conductive materials not only increases the conductivity, but also participates in the construction of the pore structure, thereby improving the comprehensive performance of carbon paper. This preparation method is relatively flexible, and the material ratio and process parameters can be adjusted according to specific needs to obtain carbon paper products with better performance.

[0027] 4. Compared with the traditional method of preparing carbon paper, the carbon fiber base paper is impregnated with resin and conductive materials, and then dried and heat treated at high temperature. The carbon paper prepared in this way often loses powder when used, such as when impregnated with PTFE, resulting in inconsistent conductivity and air permeability of the local carbon paper, affecting the overall battery performance output. The present invention adds resin and conductive materials between low-weight carbon fiber base papers. After high-temperature heat treatment, the resin forms resin carbon, which bonds part of the conductive material, and the two layers of carbon fiber base paper will wrap the microporous structure formed in the middle due to heat treatment, greatly improving the stability of the carbon paper. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the structure of carbon paper for gas diffusion layer with five carbon layer structures in Example 2.

[0029] Figure 2 It is a battery performance diagram of the gas diffusion layer made of carbon paper in Example 2 and Comparative Example 1. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] Example 1

[0032] A method for preparing carbon paper for a gas diffusion layer with a water vapor management function comprises the following steps:

[0033] (1) Preparation of odd-numbered macroporous carbon layers: The weight is 10 g / m 2 The carbon fiber base paper is immersed in a phenolic resin stock solution, and then placed in a 65° C. oven for drying for 90 minutes, wherein the phenolic resin content in the carbon fiber base paper after drying is 50% of the weight of the carbon fiber base paper;

[0034] (2) Preparation of an even-numbered layer of small-pore carbon layers: Graphite and a phenolic resin stock solution (the mass content of graphite is 10% and the mass content of the phenolic resin stock solution is 90%) are mixed and dispersed evenly, and the obtained graphite-phenolic resin dispersion is evenly coated on the impregnated paper dried in step (1) by blade coating;

[0035] (3) odd-numbered layers and even-numbered layers are alternately stacked: another sheet of the impregnated paper dried in step (1) is laminated with the impregnated paper coated with the graphite-phenolic resin dispersion in step (2), and the obtained three-layer composite structure is dried at 65° C.;

[0036] (4) Composite hot pressing: hot pressing the composite laminate structure obtained in step (3) at 140° C. and 1 MPa for 10 min;

[0037] (5) High-temperature heat treatment: The impregnated paper obtained by hot pressing in step (4) is placed in a high-temperature sintering furnace, heated to 1000°C and kept at this temperature for 1.5 hours, then heated to 2000°C and kept at this temperature for 1.5 hours, and then naturally cooled to finally produce a three-layer carbon layer structure for a gas diffusion layer carbon paper, wherein the thickness of the first and third macroporous carbon layers is 60 μm, the porosity is 85%, and the pore size is 50 μm; the thickness of the second microporous carbon layer is 10 μm, the porosity is 60%, and the pore size is 20 μm; and the overall porosity of the carbon paper is 83%.

[0038] Example 2

[0039] A method for preparing carbon paper for a gas diffusion layer with a water vapor management function comprises the following steps:

[0040] (1) Preparation of odd-numbered macroporous carbon layers: The weight is 20 g / m 2 The carbon fiber base paper is immersed in a dispersion of a phenolic resin stock solution and graphite (the mass content of the phenolic resin stock solution is 85%, and the mass content of the graphite is 15%), and is placed in an oven at 80° C. and dried for 60 minutes. The phenolic resin content in the carbon fiber base paper after drying is 100% of the weight of the carbon fiber base paper;

[0041] (2) Preparation of an even-numbered layer of small-pore carbon layers: Graphite and a phenolic resin stock solution (the mass content of graphite is 30% and the mass content of the phenolic resin stock solution is 70%) are mixed and dispersed evenly, and the obtained graphite-phenolic resin dispersion is evenly coated on the impregnated paper dried in step (1) by blade coating;

[0042] (3) Odd-numbered layers and even-numbered layers are stacked alternately: Take another sheet with a gram weight of 20 g / m 2 The carbon fiber base paper is immersed in a dispersion of a phenolic resin stock solution and graphite (the mass content of the phenolic resin stock solution is 80%, and the mass content of the graphite is 20%), and is placed in an oven at 80° C. and dried for 60 min. The phenolic resin content in the carbon fiber base paper after drying is 120% of the weight of the carbon fiber base paper. The obtained impregnated paper is laminated to the surface of the impregnated paper coated with the graphite-phenolic resin dispersion in step (2);

[0043] (4) mixing graphite and phenolic resin stock solution (graphite content 50% by mass, phenolic resin stock solution content 50% by mass), and dispersing them evenly, and applying the obtained graphite-phenolic resin dispersion evenly on the impregnated paper after bonding in step (3) by means of blade coating;

[0044] (5) Take another sheet with a weight of 20g / m 2 The carbon fiber base paper is impregnated in a dispersion of a phenolic resin stock solution and graphite (the mass content of the phenolic resin stock solution is 75%, and the mass content of the graphite is 25%), and then placed in an oven at 80° C. and dried for 60 min. The phenolic resin content in the carbon fiber base paper after drying is 120% of the weight of the carbon fiber base paper. The obtained impregnated paper is laminated with the impregnated paper coated with the graphite-phenolic resin dispersion in step (4). The obtained five-layer composite structure is dried at 80° C.;

[0045] (6) Composite hot pressing: hot pressing the composite laminate structure obtained in step (5) at 180° C. and 10 MPa for 20 min;

[0046] (7) High-temperature heat treatment: the impregnated paper after hot pressing is placed in a high-temperature sintering furnace, heated to 1200°C and kept warm for 1 hour, then heated to 2400°C, kept warm for 1 hour, and then naturally cooled to finally produce a five-layer carbon layer structure for gas diffusion layer carbon paper, wherein the first macroporous carbon layer has a thickness of 50 μm, a porosity of 80%, and a pore size of 65 μm; the third macroporous carbon layer has a thickness of 50 μm, a porosity of 75%, and a pore size of 60 μm; the fifth macroporous carbon layer has a thickness of 50 μm, a porosity of 70%, and a pore size of 55 μm; the second microporous carbon layer has a thickness of 15 μm, a porosity of 55%, and a pore size of 15 μm; the fourth microporous carbon layer has a thickness of 15 μm, a porosity of 50%, and a pore size of 10 μm; the overall porosity of the carbon paper is 79%.

[0047] Example 3

[0048] A method for preparing carbon paper for a gas diffusion layer with a water vapor management function comprises the following steps:

[0049] (1) Preparation of odd-numbered macroporous carbon layers: The weight is 30 g / m 2 The carbon fiber base paper is immersed in a dispersion of a phenolic resin stock solution and graphite (the mass content of the phenolic resin stock solution is 75%, and the mass content of the graphite is 25%), and is placed in a 95° C. oven for drying for 10 minutes. The phenolic resin content in the carbon fiber base paper after drying is 150% of the weight of the carbon fiber base paper;

[0050] (2) Preparation of an even-numbered layer of small-pore carbon layers: Graphite and a phenolic resin stock solution (the mass content of graphite is 35% and the mass content of the phenolic resin stock solution is 65%) are mixed and dispersed evenly, and the obtained graphite-phenolic resin dispersion is evenly coated on the impregnated paper dried in step (1) by blade coating;

[0051] (3) Odd-numbered layers and even-numbered layers are stacked alternately: Take another sheet with a gram weight of 30 g / m 2 The carbon fiber base paper is impregnated in a dispersion of a phenolic resin stock solution and graphite (the mass content of the phenolic resin stock solution is 70%, and the mass content of the graphite is 30%), and then placed in a 95° C. oven for drying for 10 min, wherein the phenolic resin content in the carbon fiber base paper is 170% of the weight of the carbon fiber base paper, and the obtained impregnated paper is laminated with the impregnated paper coated with the graphite-phenolic resin dispersion in step (2);

[0052] (4) mixing graphite and a phenolic resin stock solution (the mass content of graphite is 45%, and the mass content of the phenolic resin stock solution is 55%) and dispersing them uniformly, and applying the obtained graphite-phenolic resin dispersion uniformly on the impregnated paper in step (3) by blade coating;

[0053] (5) Take another sheet with a weight of 30g / m 2 The carbon fiber base paper is impregnated in a dispersion of a phenolic resin stock solution and graphite (the mass content of the phenolic resin stock solution is 65%, and the mass content of the graphite is 35%), and then placed in a 95° C. oven for drying for 10 min, wherein the phenolic resin content in the carbon fiber base paper is 190% of the weight of the carbon fiber base paper, and the impregnated paper is laminated with the impregnated paper coated with the graphite-phenolic resin dispersion in step (4);

[0054] (6) mixing graphite and phenolic resin stock solution (the mass content of graphite is 55%, and the mass content of phenolic resin stock solution is 45%), and dispersing them evenly, and applying the obtained graphite-phenolic resin dispersion evenly on the impregnated paper in the above step (5) by knife coating;

[0055] (7) Take another sheet with a weight of 30 g / m 2 The carbon fiber base paper is impregnated in a dispersion of a phenolic resin stock solution and graphite (the mass content of the phenolic resin stock solution is 60%, and the mass content of the graphite is 40%), and then placed in a 95° C. oven for drying for 10 min, wherein the phenolic resin content in the carbon fiber base paper is 210% of the weight of the carbon fiber base paper, and the obtained impregnated paper is laminated with the impregnated paper coated with the graphite-phenolic resin dispersion in step (6), and the obtained seven-layer composite structure is dried at 95° C.;

[0056] (8) Composite hot pressing: hot pressing the composite laminate structure obtained in step (7) at 240° C. and 30 MPa for 30 min;

[0057] (9) High-temperature heat treatment: The hot-pressed impregnated paper is placed in a high-temperature sintering furnace, heated to 1500°C and kept at this temperature for 0.5 hours, then heated to 2800°C and kept at this temperature for 0.5 hours before being naturally cooled to finally produce a seven-layer carbon layer structure for a gas diffusion layer carbon paper, wherein the first macroporous carbon layer has a thickness of 40 μm, a porosity of 85%, and a pore size of 70 μm; the third macroporous carbon layer has a thickness of 40 μm, a porosity of 80%, and a pore size of 60 μm; the fifth macroporous carbon layer has a thickness of 40 μm, a porosity of 80%, and a pore size of 60 μm; the fifth macroporous carbon layer has a thickness of 200 μm, a porosity of 80%, and a pore size of 70 μm. The thickness of the seventh macroporous carbon layer is 40μm, the porosity is 75%, and the pore size is 50μm; the thickness of the seventh macroporous carbon layer is 40μm, the porosity is 70%, and the pore size is 40μm; the thickness of the second microporous carbon layer is 20μm, the porosity is 60%, and the pore size is 15μm; the thickness of the fourth microporous carbon layer is 20μm, the porosity is 50%, and the pore size is 5μm; the thickness of the sixth microporous carbon layer is 20μm, the porosity is 45%, and the pore size is 2μm; the overall porosity of carbon paper is 75%.

[0058] Comparative Example 1

[0059] A method for preparing carbon paper for a gas diffusion layer comprises the following steps:

[0060] (1) Graphite and phenolic resin stock solution (the mass content of graphite is 15%, and the mass content of phenolic resin stock solution is 85%) are mixed, and the gram weight is 50g / m 2 The carbon fiber base paper is impregnated in a mixture of graphite and phenolic resin, and then placed in an oven at 80°C for drying for 60 minutes, wherein the content of phenolic resin in the carbon fiber base paper is 150% of the weight of the carbon fiber base paper;

[0061] (2) hot pressing a piece of impregnated paper in step (1) at 160° C. and 5 MPa for 10 min;

[0062] (3) The impregnated paper obtained by hot pressing in step (2) is placed in a high-temperature sintering furnace, heated to 1200° C. and kept at this temperature for 1 hour, then heated to 2400° C. and kept at this temperature for 1 hour, and then naturally cooled to finally produce carbon paper for gas diffusion layer with a quantitative thickness of 180 μm and a porosity of 79%.

[0063] The phenolic resin stock solutions in Examples 1-3 and Comparative Example 1 all adopt 2124 phenolic resin stock solution produced by Wuxi Xinyehao Chemical Co., Ltd.

[0064] The carbon papers prepared in Example 2 and Comparative Example 1 were respectively prepared into gas diffusion layers, and were respectively packaged into membrane electrodes with the same catalyst layer and proton exchange membrane. The battery performance test was carried out under the conditions of hydrogen / air inlet pressure: 1.6 / 1.5 bar; hydrogen / air flow rate: 0.5 / 1.4 L / min; anode / cathode inlet temperature: 80°C / 80°C; anode / cathode dew point temperature: 64°C / 64°C. The battery performance is shown in FIG. Figure 2 As shown, from Figure 2 It can be seen that the carbon paper obtained in Example 2 has better battery performance and better water vapor management ability.

[0065] The carbon papers prepared in Example 2 and Comparative Example 1 were subjected to physical property tests, and the test structure is shown in Table 1. It can be seen from Table 1 that the carbon paper in Example 2 has lower vertical resistance and higher air permeability.

[0066] Table 1 Physical properties of carbon paper obtained in Example 2 and Comparative Example 1

[0067] Compare Projects <![CDATA[Vertical resistance (mΩ·cm 2 )]]> <![CDATA[Air permeability cm 3 / cm 2 / cm @ 200 Pa]]> Comparative Example 1 14.72 136 Example 2 8.58 188

[0068] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A carbon paper for a gas diffusion layer having a water vapor management function, characterized in that: The invention comprises at least three layers of alternately stacked carbon layers, wherein the odd-numbered layers are macroporous carbon layers, which are formed by impregnating carbon fiber base paper in a mixture of resin and conductive material and drying the macroporous carbon layers; the even-numbered layers are microporous carbon layers, which include resin and conductive material and are coated on the surface of the odd-numbered layers; the odd-numbered layers and the even-numbered layers are compounded by a hot pressing process to form a composite material, and the composite material is subjected to high-temperature heat treatment to form a carbon paper finished product.

2. The carbon paper for gas diffusion layer with water vapor management function according to claim 1, characterized in that: The thickness of a single odd-numbered layer is 40-100 μm, the porosity is 65%-85%, and the pore size is 10-50 μm; the odd-numbered layer serves as the main supporting structure, providing macroporous channels to dominate water vapor transmission.

3. The carbon paper for gas diffusion layer with water vapor management function according to claim 1, characterized in that: The thickness of a single even-numbered layer is 10-50 μm, the porosity is 40%-60%, and the pore size is 0.5-20 μm; the even-numbered layers form small pore channels to assist water vapor transmission and enhance the overall conductivity of the carbon paper.

4. The carbon paper for gas diffusion layer with water vapor management function according to claim 1, characterized in that: The average pore size of the macroporous carbon layer is greater than the average pore size of the microporous carbon layer, and the porosity of the macroporous carbon layer is greater than the porosity of the microporous carbon layer; The pore size and porosity are achieved by adjusting the mass ratio of the conductive material to the resin and the loading amount of the mixed solution after impregnation.

5. The method for preparing carbon paper for gas diffusion layer with water vapor management function according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step S1, preparation of odd-numbered macroporous carbon layers: impregnating carbon fiber base paper in a uniform mixture of resin and conductive material, and drying the impregnated carbon fiber base paper at 65-95° C. for 10-60 min to obtain odd-numbered macroporous carbon layers; Step S2, preparation of an even-numbered small-porous carbon layer: uniformly coating a uniform mixture of resin and conductive material on the surface of an odd-numbered macroporous carbon layer to form an even-numbered small-porous carbon layer; Step S3, alternately stacking odd-numbered layers and even-numbered layers: repeating steps S1 and S2 to alternately stack odd-numbered layers and even-numbered layers to a target number of layers, and drying at 65-95° C. to obtain a composite laminate structure; Step S4, composite hot pressing: subjecting the composite laminate structure obtained in step S3 to composite hot pressing curing treatment at 80-300° C. and 0.1-30 MPa for 1-30 min; Step S5, high temperature heat treatment: subjecting the composite material after the composite hot pressing and curing in step S4 to high temperature heat treatment to obtain carbon paper for gas diffusion layer with good water vapor management capability.

6. According to the method for preparing carbon paper for gas diffusion layer with water vapor management function of claim 5, the gram weight of the carbon fiber base paper in step S1 is 10-40 g / m², and after impregnation and drying, the resin content in the carbon fiber base paper is 10%-300% of the weight of the carbon fiber base paper.

7. The method for preparing carbon paper for gas diffusion layer with water vapor management function according to claim 5, wherein the mass ratio of the resin to the conductive material in step S1 is 100-10:0-90; The mass ratio of the resin to the conductive material in step S2 is 90-10:10-90.

8. According to the method for preparing carbon paper for gas diffusion layer with water vapor management function as claimed in claim 5, the resin in step S1 and step S2 is phenolic resin and / or epoxy resin, and the conductive material is a combination of one or more of graphite powder, carbon nanotubes and conductive carbon black.

9. According to the method for preparing carbon paper for gas diffusion layer with water vapor management function of claim 5, in step S4, the composite hot pressing method adopts a hot pressing method including flat plate hot pressing and multi-roller hot pressing.

10. According to the method for preparing carbon paper for gas diffusion layer with water vapor management function of claim 5, in step S5, the conditions of high temperature heat treatment are: carbonization temperature 1000~1500℃, insulation time 0.1~2 hours, graphitization temperature 2000~2800℃, insulation time 0.1~2 hours.

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