Conductive paste for coiled material carbon paper, coiled material carbon paper and preparation method of coiled material carbon paper

Abstract

The invention provides conductive paste for coiled material carbon paper, the coiled material carbon paper and a preparation method of the coiled material carbon paper, and belongs to the technical field of fuel cells. According to the preparation method of the conductive slurry for the coiled material carbon paper, the dispersity and the stability of the conductive agent in the slurry can be improved, the coiled material carbon paper is uniformly impregnated and glued, and stable and continuous production of the coiled material carbon paper is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and particularly relates to a conductive paste for roll carbon paper, roll carbon paper and a preparation method thereof. Background Art

[0002] The membrane electrode assembly (MEA) is the core component of a proton exchange membrane fuel cell (PEMFC), the place where the hydrogen-oxygen electrochemical reaction occurs, and is assembled by a proton membrane, a catalyst layer and a gas diffusion layer (GDL). The gas diffusion layer is mainly composed of carbon paper (CP) and a microporous layer (MPL), and the carbon paper mainly functions to transport the reaction gas, collect the current generated by the reaction, and drain the reaction product water. Therefore, as an important gas-liquid transport medium in fuel cells, the electrical conductivity, mechanical properties and air permeability of carbon paper have a very important impact on the electrochemical reaction ability of fuel cells.

[0003] At present, carbon paper is mainly divided into two categories: sheet carbon paper and roll carbon paper. Sheet carbon paper has the characteristic of high electrical conductivity, and its graphitization process needs to be completed in an intermittent furnace, resulting in a long manufacturing cycle, low production efficiency and high cost. Roll carbon paper has the characteristics of high air permeability and good flexibility. The whole manufacturing process is continuous roll-to-roll production, with the advantages of high production capacity and low cost. In terms of composition, sheet carbon paper is mainly composed of a skeleton carbon fiber and a resin carbon that binds the carbon fiber. On the basis of sheet carbon paper, roll carbon paper needs to introduce a conductive agent as a third component to balance the electrical conductivity and the demand for material flexibility in the roll-to-roll continuous process. The conductive agent can effectively reduce the graphitization temperature and reduce the amount of phenolic resin used, which can not only improve the electrical conductivity of roll carbon paper, but also enhance its mechanical toughness. This improvement solves the brittleness problem of carbon paper in mechanical properties, and at the same time meets the requirements of its electrical conductivity, realizing the overall improvement of the performance of roll carbon paper.

[0004] There are many types of conductive agents, such as carbon materials like conductive carbon black, conductive graphite, carbon nanotubes, graphene, etc. These materials often exhibit surface inertness and have a small content of surface active functional groups, so it is difficult to be uniformly dispersed in water or organic solvents, and even if they can be dispersed, they are prone to sedimentation, and the stability of the slurry is difficult to control. In the laboratory or small-batch preparation stage, the stability of the conductive paste can be maintained by mechanical oscillation, ultrasonic, stirring and other methods. However, in the pilot or mass production stage, in the face of the amplification effect, circulation, transportation and other process links of the conductive paste during continuous production, mechanical methods are difficult to maintain the dispersion stability of the conductive agent and its interfacial bonding strength with carbon fibers during the carbon paper sizing process, thereby affecting the sizing effect of roll carbon paper and resulting in the mechanical properties and electrical properties of carbon paper not meeting the actual application requirements. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this purpose, an embodiment of the present invention provides a conductive paste for roll carbon paper, a roll carbon paper and a preparation method thereof.

[0006] In a first aspect, an embodiment of the present invention provides a preparation method of a conductive paste for roll carbon paper, including the following steps:

[0007] S1. Mix a first resin, a first organic solvent and a conductive agent, and perform a first stirring treatment to obtain a first mixed solution; mix a silane coupling agent and the first mixed solution, and perform a second stirring treatment to obtain a first paste;

[0008] S2. Mix a second resin, a second organic solvent and water, and perform a third stirring treatment to obtain a second mixed solution, where the mass ratio of the water to the second organic solvent is 1:(50 - 100); mix an auxiliary agent and the second mixed solution, and perform a fourth stirring treatment to obtain a second paste; where the auxiliary agent is at least one of silicate bentonite, modified polyurethane polymer, sodium carboxymethyl cellulose, carbomer and hydroxypropyl cellulose;

[0009] S3. Mix the first paste and the second paste, and perform a fifth stirring treatment under heating conditions to prepare the conductive paste.

[0010] The advantages and technical effects brought by the preparation method of the conductive paste in the embodiment of the present invention are as follows:

[0011] (1) In step S1, using the first organic solvent as the solvent can improve the dispersibility of the silane coupling agent and the coupling effect between the silane coupling agent and the conductive agent. If water is introduced into the first paste, the silane coupling agent has poor dispersibility in the water-containing solvent and will hydrolyze to produce methanol and silanol when encountering water, affecting its coupling effect on the conductive agent.

[0012] (2) Step S1 requires two times of feeding and stirring. First, the conductive agent is dispersed through the first stirring treatment, and then the silane coupling agent is added and adsorbed on the surface of the uniformly dispersed conductive agent through the second stirring treatment. If the conductive agent and the silane coupling agent are added simultaneously and only one stirring is performed, the adsorption effect of the silane coupling agent on the surface of the conductive agent is poor, and it is not easy for the conductive agent to adhere uniformly to the surface of the carbon fiber felt during subsequent sizing.

[0013] (3) In step S2, a second organic solvent and a small amount of water are used as solvents. The solvent contains both an organic solvent and a small amount of water that must be added additionally because a large number of hydrogen bonds can be formed after water is mixed with the organic solvent, and they can combine with the hydroxyl functional groups at the ends of the additives, thereby improving the solubility, dissolution efficiency of the additives, and the molecular chain extension effect. However, the mass ratio of water to the second organic solvent should be controlled within the range of 1:(50 - 100). Excessive water will cause poor solubility of the resin and affect the wettability of the resin to the carbon fiber felt.

[0014] (4) Step S2 requires feeding and stirring in two times. First, through the third stirring treatment, the second resin, the second organic solvent, and water are uniformly mixed so that a large number of hydrogen bonds can be formed after water is mixed with the organic solvent. Then, the additives are added and through the fourth stirring treatment, the molecular chains of the additives can combine with the uniformly dispersed hydrogen bonds around them during the dissolution and extension process, which helps the dissolution of the additives and the construction of the three-dimensional network structure of the molecular chains of the additives. Furthermore, after the first slurry and the second slurry are mixed in step S3, the supporting effect of the three-dimensional network structure of the molecular chains of the additives on the conductive agent is improved. If water and the additives are added simultaneously, during the dissolution and extension process of the molecular chains of the additives, there are no uniformly dispersed hydrated hydrogen bonds around them, which will affect the dissolution of the additives and the construction of the molecular chain network, and further affect the supporting effect of the molecular chain network of the additives on the conductive agent after mixing in step S3.

[0015] (5) The preparation method of the embodiment of the present invention must include the steps of preparing the first and second slurries in steps S1 and S2, and the step of heating and mixing in S3, that is, a two-step mixing method. After the first slurry is separately prepared, the conductive agent is uniformly dispersed, and the silane coupling agent is fully adsorbed on the surface of the conductive agent; after the second slurry is prepared, the molecular chains of the additives are fully extended and interact with the hydrated hydrogen bonds to form a three-dimensional network structure, and the three-dimensional network structure is used to support the above-mentioned conductive agent. Then, through step S3, the first slurry and the second slurry are mixed, and the conductive agent can be uniformly dispersed in the slurry and remain stable. If the first slurry and the second slurry are directly mixed or premixed before they are separately prepared, it is difficult for the silane coupling agent to be adsorbed on the surface of the conductive agent, and the dissolution effect of the additives is poor, and the conductive agent is unevenly dispersed and easy to settle.

[0016] (6) In step S3, the first slurry and the second slurry are miscible under heating conditions. Under the heating state, the viscosity of the slurry can be reduced, which helps the hydrogen bonds and the molecular chains of the additives to overlap and form a three-dimensional network structure, enhance the molecular support effect, and improve the stability of the conductive slurry. In addition, under the heating conditions, it helps to enhance the chemical bonding effect between the silane coupling agent, the conductive agent, and the resin, thereby improving the adhesion of the conductive agent to the carbon fiber skeleton structure of the roll carbon paper and avoiding falling off during the water and gas conduction process of the fuel cell. If the miscibility is not carried out under heating conditions, the above effects cannot be exerted, and the stability of the conductive slurry will be poor.

[0017] In some embodiments, the rotation speed of the first stirring treatment is 200 - 1500 r / min, and the time is 1 - 60 min; and / or, the rotation speed of the second stirring treatment is 200 - 1500 r / min, and the time is 1 - 60 min; and / or, the rotation speed of the third stirring treatment is 200 - 1500 r / min, and the time is 1 - 60 min; and / or, the rotation speed of the fourth stirring treatment is 200 - 1500 r / min, and the time is 1 - 24 h; and / or, the rotation speed of the fifth stirring treatment is 200 - 1500 r / min, and the time is 1 - 24 h.

[0018] In some embodiments, the mass ratio of the conductive agent to the first resin is 0.1:1 - 2:1; the mass ratio of the silane coupling agent to the first resin is 0.1:10 - 1:5; the mass ratio of the total mass of the conductive agent, the silane coupling agent and the first resin to the mass of the first organic solvent is 1:20 - 1:4.

[0019] In some embodiments, the mass ratio of the second resin to the second organic solvent is 1:20 - 1:4, and the mass ratio of the additive to the second resin is 1:1000 - 1:10.

[0020] In some embodiments, the mass ratio of the first slurry to the second slurry is 1:10 - 10:1.

[0021] In some embodiments, the heating temperature in step S3 is 30 - 50 °C.

[0022] In some embodiments, the conductive agent is at least one of carbon powder, artificial graphite powder, natural graphite powder, expanded graphite, carbon nanotubes and graphene; and / or, the first resin is at least one of epoxy resin, phenolic resin, urea-formaldehyde resin and furan resin; and / or, the first organic solvent is at least one of acetone, methanol, ethanol, n-propanol, isopropanol, N, N-dimethylpyrrolidone and N-methylpyrrolidone; and / or, the silane coupling agent is at least one of the KH550, KH560 and KH570 models;

[0023] and / or, the second resin is at least one of epoxy resin, phenolic resin, urea-formaldehyde resin and furan resin; and / or, the second organic solvent is at least one of acetone, methanol, ethanol, n-propanol, isopropanol, N, N-dimethylpyrrolidone and N-methylpyrrolidone.

[0024] In a second aspect, an electrically conductive paste for a roll carbon paper provided by an embodiment of the present invention is prepared by the method for preparing an electrically conductive paste in the first aspect.

[0025] The advantages and technical effects brought by the conductive paste for coiled carbon paper according to the embodiments of the present invention are as follows:

[0026] Due to the adoption of the preparation method of the conductive paste according to the embodiments of the present invention, the dispersibility and stability of the conductive paste according to the embodiments of the present invention are relatively high, and uniform impregnation and sizing of the coiled carbon paper can be achieved, realizing stable and continuous production of the coiled carbon paper.

[0027] Thirdly, the embodiments of the present invention provide a preparation method of coiled carbon paper, including the following steps:

[0028] (1) Sizing a carbon fiber felt with the conductive paste of the second aspect, and then performing drying treatment and hot pressing and curing treatment to obtain a coiled carbon paper after resin curing;

[0029] (2) Performing carbonization treatment and graphitization treatment on the coiled carbon paper after resin curing in an inert atmosphere to obtain the coiled carbon paper.

[0030] The advantages and technical effects brought by the preparation method of coiled carbon paper according to the embodiments of the present invention are as follows:

[0031] Due to the adoption of the conductive paste according to the embodiments of the present invention, the preparation method of coiled carbon paper according to the embodiments of the present invention is applicable to stable and continuous production.

[0032] Fourthly, the embodiments of the present invention provide a coiled carbon paper prepared by the preparation method of coiled carbon paper of the third aspect.

[0033] The advantages and technical effects brought by the coiled carbon paper according to the embodiments of the present invention are as follows:

[0034] Due to the adoption of the preparation method of coiled carbon paper according to the embodiments of the present invention, the coiled carbon paper according to the embodiments of the present invention has good uniformity, and the adhesion of the conductive agent to the fiber skeleton structure of the coiled carbon paper is high, and it is not easy to fall off during the water and gas conduction process of the fuel cell.

[0035] The attached drawings show

[0036] Figure 1 SEM of the carbon fiber paper of Example 1 and Comparative Example 1. Specific embodiments

[0037] The embodiments of the present invention are described in detail below. The examples are shown in the attached drawings. The embodiments described below by referring to the attached drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation to the present invention.

[0038] At present, the conductive paste used in the impregnation process of coil carbon paper mainly contains several main components such as solvents, resins, and conductive agents. Resins can usually be completely dissolved in solvents, while conductive agents generally choose carbon materials such as conductive carbon black, conductive graphite, carbon nanotubes, and graphene, which cannot be dissolved in solvents and are difficult to maintain stability after being dispersed by means of mechanical stirring, ultrasonic vibration, high-speed shearing, etc. Therefore, it is difficult to achieve stable control in continuous and batch production. It can be seen that achieving uniform dispersion of the conductive agent in the conductive paste is the key to the batch and continuous production of coil carbon paper. In addition, the stable combination of the conductive agent with the resin and carbon fiber is also a key factor in the performance of coil carbon paper. Based on the above premises, the embodiments of the present invention explore the preparation method of the conductive paste for coil carbon paper. The purpose is to provide a conductive paste for coil carbon paper, a coil carbon paper, and a preparation method thereof. The preparation method of the conductive paste can improve the dispersion and stability of the conductive agent in the paste, achieve uniform impregnation and sizing of the coil carbon paper, and realize the stable and continuous production of the coil carbon paper.

[0039] In the first aspect, an embodiment of the present invention provides a preparation method of a conductive paste for coil carbon paper, including the following steps:

[0040] S1. Mix the first resin, the first organic solvent, and the conductive agent, and perform a first stirring treatment to obtain a first mixed solution; mix the silane coupling agent and the first mixed solution, and perform a second stirring treatment to obtain a first paste;

[0041] S2. Mix the second resin, the second organic solvent, and water, and perform a third stirring treatment to obtain a second mixed solution, where the mass ratio of the water to the second organic solvent is 1:(50 - 100); mix the auxiliary agent and the second mixed solution, and perform a fourth stirring treatment to obtain a second paste; where the auxiliary agent is at least one of silicate bentonite, modified polyurethane polymer, sodium carboxymethyl cellulose, carbomer, and hydroxypropyl cellulose;

[0042] S3. Mix the first paste and the second paste, and perform a fifth stirring treatment under heating conditions to prepare the conductive paste.

[0043] In the preparation method of the conductive paste according to the embodiment of the present invention, a silane coupling agent is introduced into the first paste in step S1. One end of the silane coupling agent contains a vinyl unsaturated bond, and the other end contains a siloxane structure, which can produce a chemical bonding effect with the conductive agent. The vinyl unsaturated bond can produce a polycondensation effect with the resin, which can improve the bonding performance between the resin and the conductive agent after curing, and further improve the stability of the attachment of the conductive agent on the fiber skeleton structure of the coil carbon paper.

[0044] In the preparation method of the conductive paste according to the embodiment of the present invention, in step S1, using a first organic solvent as the solvent can improve the dispersibility of the silane coupling agent and the coupling effect between the silane coupling agent and the conductive agent. If water is introduced into the first paste, the silane coupling agent has poor dispersibility in the water-containing solvent and will hydrolyze to produce methanol and silanol when encountering water, which affects its coupling effect on the conductive agent.

[0045] In the preparation method of the conductive paste according to the embodiment of the present invention, step S1 requires feeding and stirring in two times. First, the conductive agent is dispersed through the first stirring treatment, and then the silane coupling agent is added and adsorbed on the surface of the uniformly dispersed conductive agent through the second stirring treatment. If the conductive agent and the silane coupling agent are added simultaneously and only stirred once, the adsorption effect of the silane coupling agent on the surface of the conductive agent is poor, and it is not easy for the conductive agent to adhere uniformly to the surface of the carbon fiber felt during subsequent sizing.

[0046] In the preparation method of the conductive paste according to the embodiment of the present invention, in step S2, a small amount of water is introduced into the second paste, and the mass ratio of water to the second organic solvent is 1:(50 - 100), such as 1:50, 1:60, 1:70, 1:80, 1:90, 1:100, etc. After a small amount of water is mixed with the organic solvent, a large number of hydrogen bonds can be formed to form a three-dimensional network structure in the solution, which has a good supporting effect on the conductive agent and helps the stable dispersion of the conductive agent in the conductive paste. If too much water is added, it will cause poor solubility of the resin and affect the wettability of the resin to the carbon fiber felt.

[0047] In the preparation method of the conductive paste according to the embodiment of the present invention, in step S2, an auxiliary agent is also introduced into the second paste. The auxiliary agent is at least one of silicate bentonite, modified polyurethane polymer, sodium carboxymethyl cellulose, carbomer, and hydroxypropyl cellulose. After these auxiliary agents are dissolved in the mixed solution, their molecular chains can be fully extended, and at the same time, the terminal hydroxyl functional groups interact with the hydrogen bonds to form a more complete three-dimensional network structure in the solution, further enhancing the supporting effect on the conductive agent and helping the stable dispersion of the conductive agent in the conductive paste.

[0048] In the preparation method of the conductive paste according to the embodiment of the present invention, in step S2, feeding and stirring are required in two times. First, the second resin, the second organic solvent and water are uniformly mixed through the third stirring process, so that a large number of hydrogen bonds can be formed after the water and the organic solvent are mixed. Then, the additive is added and through the fourth stirring process, the molecular chain of the additive binds to the uniformly dispersed hydrogen bonds around it during the dissolution and extension process, which helps the dissolution of the additive and the construction of the three-dimensional network structure of the molecular chain of the additive. Furthermore, after the first paste and the second paste are mixed in step S3, the supporting effect of the three-dimensional network structure of the molecular chain of the additive on the conductive agent is improved. If the water and the additive are added simultaneously, during the dissolution and extension process of the molecular chain of the additive, there are no uniformly dispersed hydrated hydrogen bonds around it, which will affect the dissolution of the additive and the construction of the molecular chain network, and further affect the supporting effect of the molecular chain network of the additive on the conductive agent after mixing in step S3.

[0049] The preparation method of the conductive paste according to the embodiment of the present invention adopts a two-step mixing method. In steps S1 and S2, the first paste and the second paste need to be separately prepared and then mixed in step S3. Premature mixing (referring to mixing and stirring after the first paste and the second paste have not been separately and completely stirred and dispersed) or direct mixing (without preparing the first paste and the second paste and mixing all the raw materials and then performing mixing and stirring) is not allowed. Otherwise, it will cause uneven dissolution or dispersion of the additive and the conductive agent, and the silane coupling agent cannot be fully adsorbed on the surface of the conductive agent, affecting the overall stability of the conductive paste.

[0050] In the preparation method of the conductive paste according to the embodiment of the present invention, in step S3, the fifth stirring process is carried out under heating conditions. Under the heating state, the viscosity of the paste can be reduced, which helps the hydrogen bonds and the molecular chain of the additive to overlap and form a three-dimensional network structure, improving the stabilizing ability of the additive to the conductive agent and preventing its sedimentation. At the same time, under the heating state, the bonding ability between the silane coupling agent and the conductive agent can be enhanced, improving its adsorption force on the surface of the conductive agent, and further improving the adhesion of the conductive agent to the carbon fiber of the carbon paper skeleton, avoiding shedding under the water and gas conduction action of the fuel cell.

[0051] In summary, the preparation method of the conductive paste according to the embodiment of the present invention can improve the dispersibility and stability of the conductive agent in the paste, realize uniform impregnation and sizing of the roll carbon paper, and realize stable and continuous production of the roll carbon paper.

[0052] In some embodiments, the rotation speed of the first stirring treatment is 200 - 1500 r / min, and the time is 1 - 60 min; and / or, the rotation speed of the second stirring treatment is 200 - 1500 r / min, and the time is 1 - 60 min; and / or, the rotation speed of the third stirring treatment is 200 - 1500 r / min, and the time is 1 - 60 min; and / or, the rotation speed of the fourth stirring treatment is 200 - 1500 r / min, and the time is 1 - 24 h; and / or, the rotation speed of the fifth stirring treatment is 200 - 1500 r / min, and the time is 1 - 24 h. When the rotation speed and time of the foregoing stirring treatments are within the above ranges, it is beneficial for the mixed liquid or slurry to be fully stirred, mixed, and dispersed, thereby improving the uniformity and stability of the conductive paste.

[0053] In some embodiments, the mass ratio of the conductive agent to the first resin is 0.1:1 to 2:1, such as 0.1:1, 0.2:1, 0.4:1, 0.6:1, 0.8:1, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, etc.; the mass ratio of the silane coupling agent to the first resin is 0.1:10 to 1:5, such as 0.1:10, 0.2:10, 0.4:10, 0.6:10, 0.8:10, 1:10, 1:5, etc.; the mass ratio of the total mass of the conductive agent, the silane coupling agent, and the first resin to the mass of the first organic solvent is 1:20 to 1:4, such as 1:20, 1:18, 1:16, 1:14, 1:12, 1:10, 1:8, 1:6, 1:4, etc. When the ratios of the components in the first paste are within the above ranges, it can not only improve the electrical conductivity of the roll carbon paper, but also enhance its mechanical toughness, solve the brittleness problem of the roll carbon paper in mechanical properties, meet the requirements of its electrical conductivity at the same time, and achieve an overall improvement in the performance of the roll carbon paper.

[0054] In some embodiments, the mass ratio of the second resin to the second organic solvent is 1:20 to 1:4, such as 1:20, 1:18, 1:16, 1:14, 1:12, 1:10, 1:8, 1:6, 1:4, etc.; the mass ratio of the auxiliary agent to the second resin is 1:1000 to 1:10, such as 1:1000, 1:500, 1:400, 1:300, 1:200, 1:100, 1:50, 1:20, 1:10, etc. A large number of hydrogen bonds will be generated after water and the organic solvent are miscible. The molecular chains of the auxiliary agent form a three-dimensional network structure in the solvent. By using the combined supporting effects of hydrogen bonds and the molecular chain network, the conductive agent particles are more stably dispersed in the conductive paste and are not prone to sedimentation, greatly reducing the difficulty of stable control in the batch and continuous production of the conductive paste. When the ratios of the components in the second paste are within the above ranges, it helps to fully exert the foregoing effects.

[0055] In some embodiments, the mass ratio of the first slurry to the second slurry is 1:10 to 10:1, such as 1:10, 1:8, 1:6, 1:4, 1:2, 1:1, 2:1, 4:1, 6:1, 8:1, 10:1, etc. When the mass ratio of the first slurry to the second slurry is too low, it is not conducive to improving the conductivity of the rolled carbon paper. When the mass ratio of the first slurry to the second slurry is too high, it is not conducive to improving the stability of the conductive slurry and is not conducive to enhancing the bonding ability between the conductive agent and the carbon fiber of the rolled carbon paper skeleton.

[0056] In some embodiments, the heating temperature in step S3 is 30 - 50 °C, such as 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, etc. Mixing the first slurry and the second slurry under the above-mentioned heating state helps the formation of a three-dimensional network structure by the hydrogen bond and the overlapping of the molecular chains of the auxiliary agent, enhances the molecular support effect, and improves the stability of the conductive slurry. Under the above-mentioned heating state, it helps to enhance the chemical bonding effect between the silane coupling agent, the conductive agent and the resin, thereby improving the adhesion of the conductive agent to the carbon fiber skeleton structure of the rolled carbon paper and avoiding shedding during the water and gas conduction process of the fuel cell.

[0057] In some embodiments, the conductive agent is at least one of carbon powder, artificial graphite powder, natural graphite powder, expanded graphite, carbon nanotubes and graphene.

[0058] In some embodiments, the first resin is at least one of epoxy resin, phenolic resin, urea-formaldehyde resin and furan resin; and / or, the first organic solvent is at least one of acetone, methanol, ethanol, n-propanol, isopropanol, N, N-dimethylpyrrolidone and N-methylpyrrolidone; and / or, the silane coupling agent is at least one of the models KH550, KH560 and KH570;

[0059] and / or, the second resin is at least one of epoxy resin, phenolic resin, urea-formaldehyde resin and furan resin; and / or, the second organic solvent is at least one of acetone, methanol, ethanol, n-propanol, isopropanol, N, N-dimethylpyrrolidone and N-methylpyrrolidone.

[0060] In the second aspect, an embodiment of the present invention provides a conductive slurry for rolled carbon paper, which is prepared by the preparation method of the conductive slurry in the first aspect.

[0061] Due to the adoption of the preparation method of the conductive slurry in the embodiment of the present invention, the dispersibility and stability of the conductive slurry in the embodiment of the present invention are relatively high, and uniform impregnation and sizing of the rolled carbon paper can be realized, and stable and continuous production of the rolled carbon paper can be achieved.

[0062] In the third aspect, an embodiment of the present invention provides a preparation method of a rolled carbon paper, including the following steps:

[0063] (1) Size the carbon fiber felt with the conductive paste of the second aspect, and then perform drying treatment and hot pressing and curing treatment to obtain a rolled carbon paper after resin curing;

[0064] (2) Carbonize and graphitize the rolled carbon paper after resin curing in an inert atmosphere to obtain the rolled carbon paper.

[0065] Due to the adoption of the conductive paste of the embodiment of the present invention, the preparation method of the rolled carbon paper of the embodiment of the present invention is suitable for stable and continuous production.

[0066] In a fourth aspect, an embodiment of the present invention provides a rolled carbon paper, which is prepared by the preparation method of the rolled carbon paper of the third aspect.

[0067] Due to the adoption of the preparation method of the rolled carbon paper of the embodiment of the present invention, the rolled carbon paper of the embodiment of the present invention has good uniformity, and the adhesion of the conductive agent to the fiber skeleton structure of the rolled carbon paper is high, and it is not easy to fall off during the water and gas conduction process of the fuel cell.

[0068] The present invention will be described in detail below with reference to the embodiments and the drawings.

[0069] Example 1

[0070] (1) Preparation of the conductive paste

[0071] S1. Mix 20 parts by weight of phenolic resin (viscous liquid pure resin), 80 parts by weight of isopropyl alcohol, and 10 parts by weight of conductive agent artificial graphite powder evenly, mechanically stir for 1 h at a rotation speed of 500 r / min, and then add 2 parts by weight of silane coupling agent to the mixture, and mechanically stir for 1 h at a rotation speed of 500 r / min to obtain a first paste.

[0072] S2. Mix 20 parts by weight of phenolic resin, 80 parts by weight of isopropyl alcohol, and 1 part by weight of ultrapure water evenly, mechanically stir for 1 h at a rotation speed of 500 r / min, and then add 2 parts by weight of auxiliary agent sodium carboxymethyl cellulose to the mixture, and perform high-speed dispersion stirring for 10 h. The high-speed dispersion method is disk-type dispersion, and the rotation speed is 1500 r / min to obtain a second paste.

[0073] S3. Add 50 parts by weight of the first paste to 50 parts by weight of the second paste and mix evenly, and perform high-speed dispersion stirring for 5 h under heating conditions. The high-speed dispersion method is disk-type dispersion, and the rotation speed is 1500 r / min, and the heating temperature is 40 °C to obtain a black ink-like conductive paste.

[0074] After the conductive paste is configured, take a part of the paste and let it stand. The sedimentation time of the paste is 34 h. This indicates that the prepared conductive paste has good stability and is suitable for the continuous production process of roll carbon paper.

[0075] (2) Preparation of carbon fiber paper:

[0076] Select carbon fiber felt as the substrate to carry out the preparation of carbon fiber paper. The basis weight of the carbon fiber felt raw material is 50 g / m 2 , and the thickness is 600 mm.

[0077] First, use the conductive paste to size the carbon fiber felt. After sizing, conduct a drying treatment in an oven. The drying temperature is 70 °C and the drying time is 40 min. Subsequently, conduct a secondary hot pressing and curing treatment on the resin. The hot pressing temperature is 200 °C, the hot pressing pressure is 2 MPa, and the hot pressing time is 20 min. The mass ratio of the sizing amount to the carbon fiber felt is 1.2:1.

[0078] Conduct carbonization treatment and graphitization treatment on the carbon fiber paper after resin curing under an inert atmosphere. The carbonization temperature is 1000 °C and the carbonization time is 2 h; the graphitization temperature is 1600 °C and the graphitization time is 1 h.

[0079] After the carbon fiber paper is prepared, test its surface resistance in the vertical direction. The test pressure is 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction is 6.2 mΩ / cm 2 .

[0080] Example 2

[0081] (1) Configuration of conductive paste: The preparation method is the same as that of Example 1, except that the weight of the conductive agent is halved during the preparation of the first paste, and the weight of the auxiliary agent in the second paste is halved. The specific implementation method is as follows:

[0082] S1. Mix 20 parts by weight of phenolic resin (viscous liquid pure resin), 80 parts by weight of isopropyl alcohol, and 5 parts by weight of conductive agent artificial graphite powder evenly, and mechanically stir for 1 h at a rotation speed of 500 r / min. Subsequently, add 2 parts by weight of silane coupling agent to the mixed solution and mechanically stir for 1 h at a rotation speed of 500 r / min to obtain the first paste.

[0083] S2. Mix 20 parts by weight of phenolic resin, 80 parts by weight of isopropyl alcohol, and 1 part by weight of ultrapure water evenly, and mechanically stir for 1 h at a rotation speed of 500 r / min. Subsequently, add 1 part by weight of auxiliary agent carboxymethyl cellulose sodium to the mixed solution and conduct high-speed dispersion stirring for 10 h. The high-speed dispersion method is disk-tooth dispersion, and the rotation speed is 1500 r / min to obtain the second paste.

[0084] Step S3 of this example is the same as step S3 of Example 1.

[0085] After the conductive paste is prepared, a part of the paste is taken and allowed to stand. The sedimentation time of the paste is 37 h, indicating that the prepared conductive paste has good stability and is suitable for the continuous production process of roll carbon paper.

[0086] (2) Preparation of carbon fiber paper: The same as in Example 1.

[0087] After the carbon fiber paper is prepared, its surface resistance in the vertical direction is measured under a test pressure of 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction is 7.1 mΩ / cm 2 。

[0088] Example 3

[0089] (1) Preparation of conductive paste: The same as the preparation method in Example 1, except that silicate bentonite is used as an additive when preparing the second paste.

[0090] After the conductive paste is prepared, a part of the paste is taken and allowed to stand. The sedimentation time of the paste is 32 h, indicating that the prepared conductive paste has good stability and is suitable for the continuous production process of roll carbon paper.

[0091] (2) Preparation of carbon fiber paper: The same as in Example 1.

[0092] After the carbon fiber paper is prepared, its surface resistance in the vertical direction is measured under a test pressure of 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction is 6.5 mΩ / cm 2 。

[0093] Example 4

[0094] (1) Preparation of conductive paste: The same as the preparation method in Example 1, except that modified polyurethane polymer is used as an additive when preparing the second paste.

[0095] After the conductive paste is prepared, a part of the paste is taken and allowed to stand. The sedimentation time of the paste is 33 h, indicating that the prepared conductive paste has good stability and is suitable for the continuous production process of roll carbon paper.

[0096] (2) Preparation of carbon fiber paper: The same as in Example 1.

[0097] After the carbon fiber paper is prepared, its surface resistance in the vertical direction is measured under a test pressure of 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction is 6.4 mΩ / cm 2 。

[0098] Example 5

[0099] (1) Preparation of conductive paste: The same as the preparation method in Example 1, except that carbomer is used as an additive when preparing the second paste.

[0100] After the conductive paste was prepared, a portion of the paste was allowed to stand. The sedimentation time of the paste was 32 h, indicating that the prepared conductive paste had good stability and was suitable for the continuous production process of roll carbon paper.

[0101] (2) Preparation of carbon fiber paper: The same as in Example 1.

[0102] After the carbon fiber paper was prepared, its surface resistance in the vertical direction was measured under a test pressure of 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction was 6.6 mΩ / cm 2 。

[0103] Example 6

[0104] (1) Preparation of conductive paste: The same as the preparation method in Example 1, except that hydroxypropyl cellulose was used as an auxiliary agent when preparing the second paste.

[0105] After the conductive paste was prepared, a portion of the paste was allowed to stand. The sedimentation time of the paste was 34 h, indicating that the prepared conductive paste had good stability and was suitable for the continuous production process of roll carbon paper.

[0106] (2) Preparation of carbon fiber paper: The same as in Example 1.

[0107] After the carbon fiber paper was prepared, its surface resistance in the vertical direction was measured under a test pressure of 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction was 6.3 mΩ / cm 2 。

[0108] Comparative Example 1

[0109] (1) Preparation of conductive paste: The same as the preparation method in Example 1, except that in step S1, no silane coupling agent was added during the preparation of the first paste, and steps S2 and S3 were the same as those in Example 1. The specific implementation method was as follows:

[0110] S1. 20 parts by weight of phenolic resin (viscous liquid pure resin), 80 parts by weight of isopropanol, and 10 parts by weight of conductive agent artificial graphite powder were mechanically stirred for 2 h at a rotation speed of 500 r / min to obtain the first paste.

[0111] Steps S2 and S3 were the same as those in Example 1

[0112] After the conductive paste was prepared, a portion of the paste was allowed to stand. The sedimentation time of the paste was 29 h, indicating that the absence of a silane coupling agent would affect the dispersion and stability of the conductive agent in the conductive paste.

[0113] (2) Preparation of carbon fiber paper: The same as in Example 1.

[0114] After the carbon fiber paper was prepared, its surface resistance in the vertical direction was tested under a test pressure of 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction was 7.7 mΩ / cm 2 , which was lower than the vertical resistance value of the carbon paper sample in Example 1, indicating that the interfacial bonding strength between the conductive agent and the carbon fiber felt was low during the carbon paper sizing process, and the bonding effect was poor.

[0115] Comparative Example 2

[0116] (1) Preparation of conductive paste: The preparation method was the same as that in Example 1, except that in step S1, 1 part by weight of ultrapure water was additionally added during the preparation of the first paste, and steps S2 and S3 were the same as those in Example 1. The specific implementation method was as follows:

[0117] S1. 20 parts by weight of phenolic resin (viscous liquid pure resin), 79 parts by weight of isopropyl alcohol, 10 parts by weight of conductive agent artificial graphite powder, and 1 part by weight of ultrapure water were mixed evenly, mechanically stirred for 1 h at a rotation speed of 500 r / min, and then 2 parts by weight of silane coupling agent was added to the mixed solution, and mechanically stirred for 1 h at a rotation speed of 500 r / min to obtain the first paste.

[0118] Steps S2 and S3 were the same as those in Example 1.

[0119] After the conductive paste was prepared, a part of the paste was taken and allowed to stand. The sedimentation time of the paste was 33 h. It was shown that the silane coupling agent had poor dispersibility in the water-containing organic solvent and would hydrolyze to produce methanol and silanol when encountering water, affecting its coupling effect on the conductive agent.

[0120] (2) Preparation of carbon fiber paper: The same as in Example 1.

[0121] After the carbon fiber paper was prepared, its surface resistance in the vertical direction was tested under a test pressure of 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction was 6.6 mΩ / cm 2 , which was lower than the vertical resistance value of the carbon paper sample in Example 1, indicating that the coupling effect between the conductive agent and the carbon fiber felt was not good during the carbon paper sizing process.

[0122] Comparative Example 3

[0123] (1) Preparation of conductive paste: The preparation method was the same as that in Example 1, except that in step S1, the silane coupling agent was added during the first stirring and mixing process of preparing the first paste, and the second stirring treatment was not carried out. The specific implementation method was as follows:

[0124] S1. 20 parts by weight of phenolic resin (viscous liquid pure resin), 80 parts by weight of isopropyl alcohol, 10 parts by weight of conductive agent artificial graphite powder, and 2 parts by weight of silane coupling agent were mixed evenly, mechanically stirred for 2 h at a rotation speed of 500 r / min to obtain the first paste.

[0125] Steps S2 and S3 are the same as those in Example 1.

[0126] After the conductive paste was prepared, a part of the paste was taken and allowed to stand. The sedimentation time of the paste was 30 h. It shows that when the conductive agent and the silane coupling agent were added simultaneously, the adsorption effect of the silane coupling agent on the conductive agent was poor, the conductive agent was not evenly dispersed, and its stability in the conductive paste decreased. During subsequent sizing, the conductive agent was not easily attached evenly to the surface of the carbon fiber felt.

[0127] (2) Preparation of carbon fiber paper: The same as in Example 1.

[0128] After the carbon fiber paper was prepared, its surface resistance in the vertical direction was measured under a test pressure of 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction was 6.8 mΩ / cm 2 , which was lower than the vertical resistance value of the carbon paper sample in Example 1, indicating that the conductive agent was not easily attached evenly to the surface of the carbon fiber felt.

[0129] Comparative Example 4

[0130] (1) Preparation of conductive paste: The preparation method was the same as that in Example 1, except that in step S2, sodium carboxymethyl cellulose as an additive was not added during the preparation of the second paste. Steps S1 and S3 were the same as those in Example 1. The specific implementation method was as follows:

[0131] S2. 20 parts by weight of phenolic resin (viscous liquid pure resin), 80 parts by weight of isopropyl alcohol, and 1 part by weight of ultrapure water were mixed evenly and mechanically stirred for 1 h at a rotation speed of 500 r / min, and then high-speed dispersion stirring was carried out for 10 h. The high-speed dispersion method was disk-tooth dispersion at a rotation speed of 1500 r / min to obtain the second paste.

[0132] Steps S1 and S3 were the same as those in Example 1.

[0133] After the conductive paste was prepared, a part of the paste was taken and allowed to stand. The sedimentation time of the paste was 1 h. It shows that the prepared conductive paste was unstable and not suitable for the continuous production process of roll carbon paper.

[0134] (2) Preparation of carbon fiber paper: The same as in Example 1.

[0135] After the carbon fiber paper was prepared, its surface resistance in the vertical direction was measured under a test pressure of 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction was 6.7 mΩ / cm 2 .

[0136] Comparative Example 5

[0137] (1) Preparation of conductive paste: The preparation method was the same as that in Example 1, except that in step S2, ultrapure water was not added during the preparation of the second paste. Steps S1 and S3 were the same as those in Example 1. The specific implementation method was as follows:

[0138] S2. Mix 20 parts by weight of phenolic resin (viscous liquid pure resin) and 81 parts by weight of isopropanol evenly, stir mechanically for 1 h at a rotation speed of 500 r / min, then add 2 parts by weight of the auxiliary sodium carboxymethylcellulose to the mixture, disperse and stir at high speed for 10 h. The high-speed dispersion method is disk-type dispersion, and the rotation speed is 1500 r / min to obtain the second slurry.

[0139] Steps S1 and S3 are the same as those in Example 1.

[0140] After the conductive slurry is prepared, take a part of the slurry and let it stand. The sedimentation time of the slurry is 12 h. It shows that the organic solvent without water cannot form hydrogen bonds of hydration, thus affecting the dissolution efficiency of the auxiliary and the extension effect of the molecular chain. The prepared conductive slurry is less stable and not suitable for the continuous production process of roll carbon paper.

[0141] (2) Preparation of carbon fiber paper: The same as in Example 1.

[0142] After the carbon fiber paper is prepared, test its surface resistance in the vertical direction. The test pressure is 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction is 7.1 mΩ / cm 2 。

[0143] Comparative Example 6

[0144] (1) Preparation of conductive slurry: The preparation method is the same as that in Example 1, except that in step S2, adjust the ratio of the organic solvent and ultrapure water, add a large amount of ultrapure water during the preparation of the second slurry, but maintain the total mass of the organic solvent and ultrapure water to be the same as that in Example 1. Steps S1 and S3 are the same as those in Example 1. The specific implementation method is as follows:

[0145] S2. Mix 20 parts by weight of phenolic resin (viscous liquid pure resin), 61 parts by weight of isopropanol and 20 parts by weight of ultrapure water evenly, stir mechanically for 1 h at a rotation speed of 500 r / min, then add 2 parts by weight of the auxiliary sodium carboxymethylcellulose to the mixture, disperse and stir at high speed for 10 h. The high-speed dispersion method is disk-type dispersion, and the rotation speed is 1500 r / min to obtain the second slurry.

[0146] Steps S1 and S3 are the same as those in Example 1.

[0147] After the conductive slurry is prepared, take a part of the slurry and let it stand. The sedimentation time of the slurry is 36 h. It shows that a large amount of hydrogen bonds can be formed after a large amount of water is mixed with the organic solvent, which can combine with the terminal hydroxyl functional groups of the auxiliary, thereby improving the solubility of the auxiliary, the dissolution efficiency and the extension effect of the molecular chain. However, too much water will cause poor solubility of the resin and affect the wetting property of the resin on the carbon fiber felt.

[0148] (2) Preparation of carbon fiber paper: The same as in Example 1.

[0149] After the carbon fiber paper was prepared, its surface resistance in the vertical direction was tested under a test pressure of 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction was 9.0 mΩ / cm 2 . The prepared conductive paste was relatively stable, but not suitable for the continuous production process of roll carbon paper.

[0150] Comparative Example 7

[0151] (1) Preparation of conductive paste: The same as the preparation method in Example 1, except that sodium carboxymethyl cellulose, an auxiliary agent, was added during the first stirring and mixing process for preparing the second paste, and the second stirring treatment was not carried out. Steps S1 and S3 were the same as those in Example 1. The specific implementation method was as follows:

[0152] S2. Mix 20 parts by weight of phenolic resin (viscous liquid pure resin), 80 parts by weight of isopropanol, 1 part by weight of ultrapure water, and 2 parts by weight of sodium carboxymethyl cellulose as an auxiliary agent evenly, mechanically stir for 1 h at a rotation speed of 500 r / min, and then disperse and stir at a high speed for 10 h. The high-speed dispersion method was disk-tooth type dispersion at a rotation speed of 1500 r / min to obtain the second paste.

[0153] Steps S1 and S3 were the same as those in Example 1.

[0154] After the conductive paste was prepared, a part of the paste was taken and allowed to stand. The sedimentation time of the paste was 19 h. It was shown that when water and the auxiliary agent were added simultaneously, there were no uniformly dispersed hydrated hydrogen bonds around the auxiliary agent molecular chains during the process of dissolution and extension, which would affect the dissolution of the auxiliary agent and the construction of the molecular chain network, and further affect the supporting effect of the auxiliary agent molecular chain network on the conductive agent after mixing in Step S3.

[0155] (2) Preparation of carbon fiber paper: The same as in Example 1.

[0156] After the carbon fiber paper was prepared, its surface resistance in the vertical direction was tested under a test pressure of 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction was 7.1 mΩ / cm 2 . The prepared conductive paste was relatively stable and more suitable for the continuous production process of roll carbon paper.

[0157] Comparative Example 8

[0158] (1) Preparation of conductive paste: Instead of using the two-step mixing method, the main components of the conductive paste were directly mixed by a one-step miscibility method. The specific implementation method was as follows:

[0159] Mix 40 parts by weight of phenolic resin, 160 parts by weight of organic solvent isopropanol, 10 parts by weight of conductive agent artificial graphite powder, 1 part by weight of ultrapure water, 2 parts by weight of silane coupling agent, and 2 parts by weight of auxiliary carboxymethyl cellulose sodium evenly, stir mechanically for 3 h at a rotation speed of 500 r / min, disperse and stir at high speed for 10 h, the high-speed dispersion method is disk-type dispersion, the rotation speed is 1500 r / min, disperse and stir at high speed for 5 h under heating conditions, the high-speed dispersion method is disk-type dispersion, the rotation speed is 1500 r / min, and the heating temperature is 40 °C to obtain a black ink-like conductive paste.

[0160] After the conductive paste is prepared, take a part of the paste and let it stand. The sedimentation time of the paste is 2 h. It shows that when the first and second pastes are directly mixed without being separately prepared, it is difficult for the silane coupling agent to adsorb on the surface of the conductive agent, and the dissolution effect of the auxiliary agent is not good. The conductive agent is not evenly dispersed and is easy to settle. The prepared conductive paste has insufficient stability and is not suitable for the continuous production process of roll carbon paper.

[0161] (2) Preparation of carbon fiber paper: The same as in Example 1.

[0162] After the carbon fiber paper is prepared, test its surface resistance in the vertical direction, and the test pressure is 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction is 8.6 mΩ / cm 2 。

[0163] Comparative Example 9

[0164] (1) Preparation of conductive paste: The same as the preparation method in Example 1, except that in step S3, the fifth stirring and mixing is not carried out under heating conditions. Steps S1 and S2 are the same as those in Example 1. The specific implementation method is as follows:

[0165] S3: Add 50 parts by weight of the first paste to 50 parts by weight of the second paste and mix evenly. Disperse and stir at high speed for 5 h at room temperature of 25 °C. The high-speed dispersion method is disk-type dispersion, and the rotation speed is 1500 r / min to obtain a black ink-like conductive paste.

[0166] After the conductive paste is prepared, take a part of the paste and let it stand. The sedimentation time of the paste is 30 h. It shows that when the stirring is not carried out under heating conditions, the viscosity of the paste is too high, the conductive agent and the auxiliary agent cannot be fully and evenly mixed, and the stability of the paste decreases.

[0167] (2) Preparation of carbon fiber paper: The same as in Example 1.

[0168] After the carbon fiber paper is prepared, test its surface resistance in the vertical direction, and the test pressure is 1 MPa. The surface resistance of the carbon fiber paper in the vertical direction is 7.2 mΩ / cm 2 。

[0169] Table 1. Sedimentation time of conductive paste and surface resistance in the vertical direction of carbon fiber paper for each example and comparative example

[0170] Settling time of conductive paste Surface resistance of carbon fiber paper in the vertical direction Example 1 34h <![CDATA[6.2mΩ / cm 2 > Example 2 37h <![CDATA[7.1mΩ / cm 2 > Example 3 32h <![CDATA[6.5mΩ / cm 2 > Example 4 33h <![CDATA[6.4mΩ / cm 2 > Example 5 32h <![CDATA[6.6mΩ / cm 2 > Example 6 34h <![CDATA[6.3mΩ / cm 2 > Comparative Example 1 29h <![CDATA[7.7mΩ / cm 2 > Comparative Example 2 33h <![CDATA[6.6mΩ / cm 2 > Comparative Example 3 30h <![CDATA[6.8mΩ / cm 2 > Comparative Example 4 1h <![CDATA[6.7mΩ / cm 2 > Comparative Example 5 12h <![CDATA[7.1mΩ / cm 2 > Comparative Example 6 36h <![CDATA[9.0mΩ / cm 2 > Comparative Example 7 19h <![CDATA[7.1mΩ / cm 2 > Comparative Example 8 2h <![CDATA[8.6mΩ / cm 2 > Comparative Example 9 30h <![CDATA[7.2mΩ / cm 2 >

[0171] As can be seen from Table 1, the conductive paste of Example 1 has good stability, and at the same time, the surface resistance of the carbon fiber paper prepared in the vertical direction is relatively low, indicating that there is more graphite powder attached to the carbon fiber. The ratio of the conductive agent and the auxiliary agent in Example 2 is halved. Although the sedimentation time is slightly increased, the surface resistance of the carbon fiber paper prepared in the vertical direction is higher than that of Example 1. Examples 3, 4, 5, and 6 use different types of auxiliary agents, and relatively stable slurries can be obtained. However, considering the sedimentation time and the vertical resistance of the carbon paper samples comprehensively, the effect of the auxiliary agent is not as good as that of the auxiliary agent in Example 1.

[0172] Comparative Examples 1, 2, and 3 are comparative samples without adding silane coupling agent in step S1, adding water in step S1, and not using step-by-step miscible configuration of the first paste respectively. The sedimentation time of the prepared paste is 29 - 33 h, and the vertical resistance is 6.6 - 7.7 mΩ / cm 2 This indicates that the dispersibility of the silane coupling agent in the first paste and its adsorption effect on the conductive agent are both affected to a certain extent. The adhesion and adhesion amount of the conductive agent are small. Therefore, the sedimentation time of the conductive paste and the vertical resistance of the carbon paper sample are slightly lower than those of the sample in Example 1. Comparative Examples 4 and 5 are comparative samples without adding auxiliary agent in step S2 and without adding water in step S2 respectively. The sedimentation time of the conductive paste is short, being 1 h and 12 h, indicating that without the auxiliary agent or water, the conductive paste cannot form a molecular network structure jointly anchored and overlapped by the auxiliary agent molecular chain and the hydrated hydrogen bond, and thus cannot produce an effective supporting effect on the conductive agent. Therefore, the conductive paste is unstable and the sedimentation time is fast. Comparative Example 6 is a comparative sample with a large amount of water added in step S2. The sedimentation time of its conductive paste sample is 36 h, which is relatively stable, but the vertical resistance of the carbon paper sample is 9.0 mΩ / cm 2 This is because the presence of a large amount of water will affect the solubility and wettability of the resin, thereby affecting the interfacial bonding strength between the carbon fiber felt and the conductive agent during the carbon paper sizing process. Comparative Example 7 is a comparative sample without using step-by-step miscible configuration of the second paste in step S2. Both the conductive paste and the vertical resistance of the carbon paper are not good, indicating that the dissolution and dispersion effects of the auxiliary agent are poor. Comparative Examples 8 and 9 are comparative samples of one-step miscible configuration of the conductive paste and the fifth miscible without heating in step S3 respectively. The dispersion and adsorption effects of the silane coupling agent and the dissolution and dispersion effects of the auxiliary agent are both affected to a certain extent, and the sedimentation time of the conductive paste and the vertical resistance of the carbon paper sample are not good.

[0173] Figure 1SEM images of the carbon fiber papers of Example 1 and Comparative Example 1. The SEM results show that there is more conductive agent attached to the carbon fiber paper sample of Example 1 with the addition of silane coupling agent, while in Comparative Example 1 without the addition of silane coupling agent, the amount of conductive agent attached is less, indicating that the silane coupling agent can enhance the adhesion and the amount of conductive agent attached in the carbon fiber paper.

[0174] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0175] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a conductive slurry for roll carbon paper, characterized in that: The following steps are involved: S1. mixing a first resin, a first organic solvent and a conductive agent, and performing a first stirring treatment to obtain a first mixed solution; mixing a silane coupling agent and the first mixed solution, and performing a second stirring treatment to obtain a first slurry; S2. Mixing the second resin, the second organic solvent and water, and stirring for the third time to obtain a second mixed solution, wherein the mass ratio of the water to the second organic solvent is 1:(50-100); mixing the auxiliary agent with the second mixed solution, and stirring for the fourth time to obtain a second slurry; wherein the auxiliary agent is at least one of silicate bentonite, modified polyurethane polymer, sodium carboxymethyl cellulose, carbomer and hydroxypropyl cellulose; S3. Mix the first slurry and the second slurry, and perform a fifth stirring treatment under heating conditions to obtain the conductive slurry.

2. The preparation method according to claim 1, characterized in that: The rotation speed of the first stirring treatment is 200-1500r / min, and the time is 1-60min; and / or, the rotation speed of the second stirring treatment is 200-1500r / min, and the time is 1-60min; and / or, the rotation speed of the third stirring treatment is 200-1500r / min, and the time is 1-60min; and / or, the rotation speed of the fourth stirring treatment is 200-1500r / min, and the time is 1-24h; and / or, the rotation speed of the fifth stirring treatment is 200-1500r / min, and the time is 1-24h.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the conductive agent to the first resin is 0.1:1 to 2:1; the mass ratio of the silane coupling agent to the first resin is 0.1:10 to 1:5; the mass ratio of the total mass of the conductive agent, the silane coupling agent and the first resin to the first organic solvent is 1:20 to 1:

4.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the second resin to the second organic solvent is 1:20 to 1:4, and the mass ratio of the auxiliary agent to the second resin is 1:1000 to 1:

10.

5. The preparation method according to claim 1, characterized in that: The mass ratio of the first slurry to the second slurry is 1:10 to 10:

1.

6. The preparation method according to claim 1, characterized in that: The heating temperature in step S3 is 30-50°C.

7. The preparation method according to claim 1, characterized in that: The conductive agent is at least one of carbon powder, artificial graphite powder, natural graphite powder, expanded graphite, carbon nanotubes and graphene; and / or, the first resin is at least one of epoxy resin, phenolic resin, urea-formaldehyde resin and furan resin; and / or, the first organic solvent is at least one of acetone, methanol, ethanol, n-propanol, isopropanol, N,N-dimethylpyrrolidone and N-methylpyrrolidone; and / or, the silane coupling agent is at least one of KH550, KH560 and KH570; And / or, the second resin is at least one of epoxy resin, phenolic resin, urea-formaldehyde resin and furan resin; and / or, the second organic solvent is at least one of acetone, methanol, ethanol, n-propanol, isopropanol, N,N-dimethylpyrrolidone and N-methylpyrrolidone.

8. A conductive slurry for roll carbon paper, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

9. A method for preparing a roll of carbon paper, characterized in that: The following steps are involved: (1) Sizing the carbon fiber felt using the conductive paste described in claim 8, and then drying and hot pressing to obtain a coiled carbon paper after resin curing; (2) subjecting the carbon paper roll after the resin is cured to carbonization and graphitization in an inert atmosphere to obtain the carbon paper roll.

10. A roll of carbon paper, characterized in that: Prepared by the preparation method described in claim 9.

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