Hydrogen fuel cell bipolar plate containing dynamic imine bond resin matrix and preparation method of hydrogen fuel cell bipolar plate

Abstract

The invention provides a hydrogen fuel cell bipolar plate containing a dynamic imine bond resin matrix and a preparation method of the hydrogen fuel cell bipolar plate, and belongs to the technical field of hydrogen fuel cells, reinforced conductive fibers, conductive filler, dynamic imine bond matrix resin and a functional additive are kneaded to form a bulk molding compound, and the bulk molding compound is used for preparing the bipolar plate. The reinforced conductive fiber in the bulk molding compound is used as a reinforcing material, so that the strength and the conductivity of the composite material can be improved, the air tightness of the composite material can be enhanced by adding the conductive filler, and a complete conductive network is formed. The resin containing the dynamic imine bonds is used, interface bonding of the conductive filler and a base material can be improved, interface resistance is reduced, the conductivity of the material is effectively improved, and due to existence of reversible covalent bonds, the product has the characteristics of remoldability and degradability and has important significance in the aspects of environmental protection and sustainable development.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen fuel cells, and in particular relates to a hydrogen fuel cell bipolar plate containing a dynamic imine bond resin matrix and a preparation method thereof. Background Art

[0002] Hydrogen fuel cells, as efficient and clean energy conversion devices, are widely used in transportation, power storage, and other fields. Hydrogen fuel cells are the core power source of fuel cell vehicles, and bipolar plates are the core material of fuel cells, accounting for approximately 24% of the fuel cell cost. Bipolar plates, also known as current collectors, collect current, channel reactant gases, and separate oxidants and reductants. The performance of bipolar plates depends on material properties, flow field design, and processing technology. Currently, graphite and metal bipolar plates are commonly used in hydrogen fuel cells. Metal bipolar plates are not corrosion-resistant in long-term operation and have a limited service life. Graphite has the best corrosion resistance and high electrical conductivity, but it is expensive, accounting for approximately 50% to 60% of the battery cost. Carbon fiber composite bipolar plates combine the corrosion resistance of graphite with the high strength of metal and are hailed as the third-generation core technology that will enable the widespread application of hydrogen fuel cells in the future. However, composite bipolar plates currently generally use thermosetting resins, such as vinyl resin, unsaturated resin, epoxy resin, phenolic resin, etc. The products are not reshapeable or recyclable, resulting in a large amount of resource waste after use and unsustainable development. At the same time, such thermosetting resins will greatly reduce the conductivity of the bipolar plates.

[0003] This patent application proposes a hydrogen fuel cell bipolar plate and its preparation containing a dynamic imine bond resin matrix. A resin containing a dynamic imine bond is developed as a bipolar plate matrix resin. Due to the presence of reversible covalent bonds, the product has the characteristics of being reshapeable and degradable, which is of great significance in terms of environmental protection and sustainable development. Summary of the Invention

[0004] In order to solve the problem that currently commonly used composite material bipolar plates are not reshapeable and recyclable, the present invention provides a hydrogen fuel cell bipolar plate containing a dynamic imine bond resin matrix and a preparation method thereof. The bipolar plate prepared by the present invention is reshapeable and recyclable, avoiding the technical problems of large-scale resource waste after use, unsustainable development, and reduced conductivity of the bipolar plate caused by such thermosetting resins.

[0005] Technical solution: A hydrogen fuel cell bipolar plate containing a dynamic imine bond resin matrix, wherein the hydrogen fuel cell bipolar plate is prepared by mixing a resin containing a dynamic imine bond, reinforced conductive fiber, conductive filler and functional additives into a bulk molding compound, and then prepared by hot pressing; the functional additives include a conductive filler interface modifier and a dispersant.

[0006] Furthermore, the bipolar plate is repairable, and cracks in a bipolar plate during use can be repaired under the conditions of 160-180° C., 8-10 MPa, and pressure maintenance for 10-20 minutes.

[0007] Furthermore, the bipolar plate is recyclable. Scrapped bipolar plates are crushed and dissolved in a mixed solvent of hydrochloric acid (hydrochloric acid concentration is 0.1 mol / L) and tetrahydrofuran (volume ratio 2:8). The mixture is stirred at 50-60° C. for 60-90 minutes. The resin containing dynamic imine bonds is decomposed again into compounds with amino and aldehyde terminal groups. The conductive filler, reinforcing conductive fiber, and resin can be recycled and reused.

[0008] Furthermore, the structural formula of the resin containing the dynamic imine bond is as follows:

[0009]

[0010] Wherein, R1 is H or -OCH3; R2 is 、 、 、 、 One of the following;

[0011] n in is 2, 4, 5, 6; The n in this example is 2, 4, 5, or 6.

[0012] Furthermore, the resin containing dynamic imine bonds is prepared by:

[0013] Step (1), mixing the monomer containing aldehyde groups and hydroxyl groups and the diamine compound in ethanol, wherein the molar ratio of the monomer containing aldehyde groups and hydroxyl groups to the diamine compound is 2:1, heating the mixture at 50-100° C. for 2-6 hours, and removing the ethanol by concentration to obtain the corresponding monomer;

[0014] The structural formula of the monomer containing aldehyde group and hydroxyl group is as follows:

[0015]

[0016] The structural formula of the diamine compound is: H2N-R2-NH2.

[0017] Step (2): dissolving the monomer prepared in step (1) in ethanol, adding 2-4 times the molar amount of epichlorohydrin and 1000-5000 ppm of tetrabutylammonium bromide to the monomer, heating to 80-100° C., reacting for 1-2 hours, and then adding excess NaOH to terminate the reaction. After cooling to room temperature, extraction is performed using dichloromethane. After the extraction is completed and the solvent is evaporated, a resin matrix containing dynamic imine bonds can be obtained.

[0018] Furthermore, the curing agent used is one of the following structures:

[0019] .

[0020] Furthermore, the conductive filler is one of graphite powder (including natural flake graphite, spherical graphite, expanded graphite, artificial graphite), carbon fiber powder (CF), acetylene black (AB), carbon nanotubes (CNT), carbon black (CB), graphene, metal-modified nickel-coated graphite powder, metal-modified nickel-coated carbon nanotubes

[0021] Furthermore, the reinforcing conductive fiber is one of carbon fiber, nickel-plated carbon fiber, and silver-plated carbon fiber, with a fiber length of 3-5 cm, a fiber diameter of 6-12 μm, and a fiber conductivity of 10 4 -10 6 S / m.

[0022] Furthermore, the conductive filler interface modifier is BYK-C8013, and the dispersant is BKY-W9010.

[0023] Furthermore, the content of each raw material in the bulk molding compound is as follows:

[0024] Resin: 17wt~22wt%,

[0025] Curing agent: 2wt~5wt%,

[0026] Conductive filler: 10wt~25wt%,

[0027] Reinforced conductive fiber: 45wt~60wt%,

[0028] Functional additives: 1wt~2wt%, in which the mass ratio of the interfacial modifier and the dispersant is 1:1.

[0029] The present invention also provides a method for preparing a hydrogen fuel cell bipolar plate, comprising the following steps:

[0030] S1. Weigh the conductive filler (according to the ratio), vigorously stir and disperse it with a high-speed shear mixer for 5-10 minutes at a stirring speed of 4000-12000 rpm, then add the interfacial modifier and dispersant (according to the ratio) and continue stirring for 10 minutes to obtain a powder;

[0031] S2. Add the powder and resin that are uniformly dispersed and stirred into a kneader or planetary mixer according to the proportion and further mix them. The kneading temperature is less than 65° C. and the mixture is mixed for 30-50 minutes to obtain a premixed slurry.

[0032] S3. Add the premixed slurry into a Z-type reamer mixer or a planetary mixer, add the dried reinforced conductive fiber, stir for 10-15 minutes, then pour out the mass, stirring at a speed of 4000-12000 rpm;

[0033] S4, pouring the mass into the extruder storage bin, and squeezing the mass to the molding port through the rotation of the screw of the extrusion system, and shaping it through the molding port; when the mass reaches the required size or weight, the upper cutting system cuts the mass into pieces, and the cut mass is mechanically conveyed to a belt scale for weighing, and after drying, the mass molding compound is obtained, which is sealed with polyester film and stored for future use;

[0034] S5: The prepared bulk molding compound is directly hot-pressed to prepare bipolar plates in one step, with a mold temperature of 100-160°C, a molding pressure of 10-20 MPa, and a holding time of 10-20 min.

[0035] Specifically, the mold is heated to 100-160°C, the mold is opened, and a sufficient amount of bulk molding compound is weighed according to the product model, placed into the mold, and the mold is closed. The mold closing pressure is set to 10-20 MPa, and the mold pressure holding time is 10-20 minutes;

[0036] S6: After the pressure maintenance is completed, the mold is opened to remove the formed bipolar plate and remove the burrs;

[0037] S7: Check whether the bipolar plates have cracks. If there are cracks, repair the bipolar plates at 160-180℃ and pressure 8-10 MPa for 10-20 minutes.

[0038] S8: Test the resistivity and bending strength, and use the resistivity to calculate the conductivity of the bipolar plate.

[0039] Furthermore, the bending strength and resistivity were tested according to the standard GB / T 20042.6-2011, and the conductivity was calculated.

[0040] Beneficial effects:

[0041] (1) Currently, composite bipolar plates generally use thermosetting resins, such as vinyl resins, unsaturated resins, epoxy resins, and phenolic resins. These products are not recyclable or recyclable, resulting in a large amount of resource waste after use, which is unsustainable. The present invention proposes a hydrogen fuel cell bipolar plate containing a dynamic imine bond resin matrix, which uses a resin containing a dynamic imine bond as the bipolar plate matrix resin. Due to the presence of reversible covalent bonds, cracked bipolar plates can be repaired at 160-180°C, a pressure of 8-10 MPa, and a pressure holding time of 10-20 minutes. The scrapped bipolar plates are crushed and dissolved in a mixed solvent of hydrochloric acid (hydrochloric acid concentration is 0.1 mol / L) and tetrahydrofuran (volume ratio 2:8). Stirring is carried out at 50-60°C for 60-90 minutes. The matrix resin is decomposed again into compounds with amino and aldehyde end groups. The conductive filler, conductive fiber, and matrix resin can be recycled and reused.

[0042] (2) Whether using thermosetting or thermoplastic resins, conventional composite bipolar plates have reduced electrical conductivity. Schiff base resins, due to the presence of reversible imine bonds (C=N) sharing electron pairs, can improve the interfacial bonding between the conductive filler and the matrix material, reduce interfacial resistance, and effectively enhance the conductivity of the material. The product is remodelable and degradable, which is of great significance in terms of environmental protection and sustainable development.

[0043] (3) Reinforced conductive fibers as reinforcing materials can increase the strength and conductivity of bipolar plates. The addition of conductive fillers can enhance the air tightness of composite materials and form a complete conductive network. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a process flow chart for hydrogen fuel cell bipolar plates containing a dynamic imine bond resin matrix. DETAILED DESCRIPTION

[0045] The technical solutions of the present invention are described in detail below through examples, but the protection scope of the present invention is not limited to the examples.

[0046] In the examples, the raw materials: conductive graphite powder and conductive carbon black were purchased from Qingdao Risheng Graphite, dispersants and interfacial modifiers were purchased from BYK Chemical, curing agents were purchased from Wuxi Xihua Chemical, and carbon fibers and silver-coated carbon fibers were purchased from Zhongfu Shenying.

[0047] The conductive filler interface modifier is BYK-C8013, with a density of 1.1 g / ml and an active ingredient content of ≥90%. The dispersant is BKY-W9010, a copolymer solution containing acidic groups, with a density of approximately 1.16 g / ml and an active ingredient content of 100%.

[0048] Example 1

[0049] The processing flow chart of hydrogen fuel cell bipolar plates containing dynamic imine bond resin matrix is ​​as follows Figure 1 The specific steps are as follows:

[0050] S1. The resin matrix preparation method is as follows:

[0051] A monomer containing aldehyde and hydroxyl groups and a diamine compound are mixed in ethanol at a molar ratio of 2:1. The mixture is heated at 80°C for 4 hours, and the ethanol is removed by concentration to obtain the corresponding monomer. The monomer is dissolved in ethanol, and epichlorohydrin (3 times the molar amount of the monomer) and 4000 ppm of tetrabutylammonium bromide are added. The mixture is heated to 90°C and allowed to react for 1.5 hours. After this, an excess of NaOH is added to terminate the reaction. After cooling to room temperature, the mixture is extracted with dichloromethane. After the solvent evaporates, a resin matrix containing dynamic imine bonds is obtained.

[0052] S2. Take a conductive graphite powder: conductive carbon black mass ratio of 32:2, weigh 66 g of graphite powder and carbon black at 20 wt%, vigorously stir and disperse them with a high-speed shear mixer for 5 minutes at a stirring speed of 6000 rpm, then weigh 3.3 g of interfacial modifier at 1 wt% and add it, and then weigh 3.3 g of dispersant at 1 wt% and add it, and continue stirring for 10 minutes to obtain a powder.

[0053] S3, take 20wt% of the resin (66g), take 3wt% of the curing agent (9.9g), add the powder, resin and curing agent stirred and dispersed evenly in S2 into a kneader and further mix them at a kneading temperature of 50°C for 45 minutes.

[0054] (1) Use resin with the following structural formula:

[0055]

[0056] Wherein, R1 is -H, and R2 is: .

[0057] (2) Curing agent used: .

[0058] The molar ratio of epoxy group to hydrogen is 1:1 (in the resin molar ratio of H on the amino group of the curing agent).

[0059] S4. Add the premixed slurry into a planetary mixer, take 55wt% of the dried carbon fiber, i.e. 181.5g, put it into the mixer and stir for 15 minutes, then pour out the mass, stirring at 8000 rpm.

[0060] S5. The pellets are poured into the extruder's hopper. The screw of the extrusion system rotates and squeezes the pellets to the molding port, where they are shaped. When the pellets reach 110g, the upper cutting system cuts the pellets into pieces. The cut pellets are then mechanically conveyed to a belt scale for weighing. After drying, they are sealed with polyester film and stored for future use.

[0061] S6: Heat the molding mold to 120° C., open the mold, weigh 110 g of the bulk molding compound, put it into the mold, and close the mold. The mold closing pressure is set to 15 MPa, and the mold holding time is 15 min.

[0062] S7: After the pressure holding is completed, the mold is opened to take out the formed bipolar plate and remove the burrs.

[0063] S8: Check whether the bipolar plates have cracks. If there are cracks in the bipolar plates, keep the pressure at 180℃ and 10 MPa for 15 minutes to repair the defects.

[0064] S9: Test the resistivity and bending strength, and use the resistivity to calculate the conductivity of the bipolar plate.

[0065] Example 2

[0066] In Example 2, S1, S2, S4-S9 are the same as in Example 1, and only S3 is different from Example 1. The details of S3 are as follows:

[0067] Take 20wt% of the resin, weigh 66g of the resin, take 3wt% of the curing agent, weigh 9.9g of the curing agent, add the evenly dispersed powder, resin and curing agent into a kneader and further mix them at a kneading temperature of 50°C for 45 minutes;

[0068] (1) The resin adopts the following structure:

[0069] .

[0070] Wherein, R1 is -OCH3, R2 is: .

[0071] (2) Curing agent used: .

[0072] The molar ratio of epoxy groups to hydrogen is 1:1.

[0073] Example 3

[0074] In Example 3, S1, S2, S4-S9 are the same as in Example 1, and only S3 is different from Example 1. The details of S3 are as follows:

[0075] Take 20wt% of the resin, weigh 66g of the resin, take 3wt% of the curing agent, weigh 9.9g of the curing agent, add the evenly dispersed powder, resin and curing agent into a kneader and further mix them at a kneading temperature of 50°C for 45 minutes;

[0076] (1) The resin adopts the following structure:

[0077] .

[0078] Wherein, R1 is -OCH3, and R2 is: .

[0079] (2) Curing agent used: .

[0080] The molar ratio of epoxy groups to hydrogen is 1:1.

[0081] Example 4

[0082] In Example 4, S1-S3 and S5-S9 are the same as in Example 1, and only S4 is different from Example 1. The details of S4 are as follows:

[0083] The premixed slurry was added to a planetary mixer, and 55 wt% (181.5 g) of the dried silver-plated carbon fiber was placed in the mixer and stirred for 15 minutes at a stirring speed of 8000 rpm.

[0084] Example 5

[0085] In Example 5, S1, S2, S4-S9 are the same as in Example 1, and only S3 is different from Example 1. The details of S3 are as follows:

[0086] Take 20wt% of the resin, weigh 66g of the resin, take 3wt% of the curing agent, weigh 9.9g of the curing agent, add the evenly dispersed powder, resin and curing agent into a kneader and further mix them at a kneading temperature of 50°C for 45 minutes;

[0087] (1) The resin adopts the following structure:

[0088] .

[0089] Wherein, R1 is -H, and R2 is: .

[0090] (2) Curing agent used: .

[0091] The molar ratio of epoxy groups to hydrogen is 1:1.

[0092] Example 6

[0093] In Example 6, S1, S2, S4-S9 are the same as in Example 1, and only S3 is different from Example 1. The details of S3 are as follows:

[0094] Take 20wt% of the resin, weigh 66g of the resin, take 3wt% of the curing agent, weigh 9.9g of the curing agent, add the evenly dispersed powder, resin and curing agent into a kneader and further mix them at a kneading temperature of 50°C for 45 minutes;

[0095] (2) The resin adopts the following structure:

[0096] .

[0097] Wherein, R1 is -H, and R2 is: .

[0098] (2) Curing agent used: .

[0099] The molar ratio of epoxy groups to hydrogen is 1:1.

[0100] Example 7

[0101] In Example 7, S1, S2, S4-S9 are the same as in Example 1, and only S3 is different from Example 1. The details of S3 are as follows:

[0102] Take 20wt% of the resin, weigh 66g of the resin, take 3wt% of the curing agent, weigh 9.9g of the curing agent, add the evenly dispersed powder, resin and curing agent into a kneader and further mix them at a kneading temperature of 50°C for 45 minutes;

[0103] (1) The resin adopts the following structure:

[0104]

[0105] Wherein, R1 is -H, and R2 is: , n is 2.

[0106] (2) Curing agent used: .

[0107] The molar ratio of epoxy groups to hydrogen is 1:1.

[0108] Example 8

[0109] In Example 8, S1, S2, S4-S9 are the same as in Example 1, and only S3 is different from Example 1. The details of S3 are as follows:

[0110] Take 20wt% of the resin, weigh 66g of the resin, take 3wt% of the curing agent, weigh 9.9g of the curing agent, add the evenly dispersed powder, resin and curing agent into a kneader and further mix them at a kneading temperature of 50°C for 45 minutes;

[0111] (1) Use resin with the following structural formula:

[0112]

[0113] Wherein, R1 is -H, and R2 is: .

[0114] (2) Curing agent used: .

[0115] The molar ratio of epoxy groups to hydrogen is 1:1.

[0116] Example 9

[0117] In Example 9, S1 to S9 are the same as in Example 1. However, S10 and S11 are added. The details of S10 and S11 are as follows:

[0118] S10: Take the cracked bipolar plate and test its bending strength and resistivity.

[0119] S11: The cracked bipolar plate is placed at 180°C and a pressure of 10 MPa for 15 minutes. After the defects are repaired, the bending strength and resistivity are tested.

[0120] Example 10

[0121] S1. Take a conductive graphite powder: conductive carbon black mass ratio of 32:2, weigh 66g of graphite powder and carbon black at 20wt%, vigorously stir and disperse them with a high-speed shear mixer for 5 minutes at a stirring speed of 6000 rpm, then weigh 3.3g of interfacial modifier at 1wt% and add it, and then weigh 3.3g of dispersant at 1wt% and add it, and continue stirring for 10 minutes to obtain a powder.

[0122] S2, take 20wt% of the resin (66g), take 3wt% of the curing agent (9.9g), add the powder, resin and curing agent stirred and dispersed evenly in S2 into a kneader and further mix them at a kneading temperature of 50°C for 45 minutes.

[0123] (1) The resin used is bisphenol A epoxy resin E51 produced by Nantong Xingchen Synthetic Materials Co., Ltd.;

[0124] (2) Curing agent used: .

[0125] S3. Add the premixed slurry into a planetary mixer, take 55wt% of the dried carbon fiber, i.e. 181.5g, put it into the mixer and stir for 15 minutes, then pour out the mass, stirring at 8000 rpm.

[0126] S4. The pellets are poured into the extruder's hopper. The screw of the extrusion system rotates and squeezes the pellets to the molding port, where they are shaped. When the pellets reach 110g, the upper cutting system cuts the pellets into pieces. The cut pellets are then mechanically conveyed to a belt scale for weighing. After drying, they are sealed with polyester film and stored for future use.

[0127] S5: Heat the molding mold to 120° C., open the mold, weigh 110 g of the bulk molding compound, put it into the mold, and close the mold. The mold closing pressure is set to 15 MPa, and the mold holding time is 15 min.

[0128] S6: After the pressure holding is completed, the mold is opened to take out the formed bipolar plate and remove the burrs.

[0129] S7: Test the resistivity and bending strength, and use the resistivity to calculate the conductivity of the bipolar plate.

[0130] The bending strength and resistivity were tested according to the standard GB / T 20042.6-2011. The test results of the conductivity and bending strength of Examples 1 to 10 are as follows:

[0131] Table 1 Electrical conductivity and bending strength of Examples 1-7 of the present invention

[0132] In the resin of the present invention, different R2 structures result in different flexural strengths, while different R1 structures have almost no effect on flexural strength. Resins without imine bonds are not repairable. The use of resins containing dynamic imine bonds in this method can improve the interfacial bonding between the conductive filler and the matrix material, reduce interfacial resistance, and effectively enhance the conductivity of the material. Due to the presence of reversible covalent bonds, the product possesses remodelable and degradable properties, which is of great significance in terms of environmental protection and sustainable development.

[0133] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes may be made to the form and details without departing from the spirit and scope of the present invention.

Claims

1. A hydrogen fuel cell bipolar plate containing a dynamic imine bond resin matrix, characterized in that: The hydrogen fuel cell bipolar plate is prepared by mixing a resin containing dynamic imine bonds, reinforced conductive fibers, conductive fillers and functional additives into a bulk molding compound, and then forming the compound by hot pressing; the functional additives include a conductive filler interface modifier and a dispersant.

2. The bipolar plate according to claim 1, characterized in that The bipolar plate is repairable, and a cracked bipolar plate can be repaired under the conditions of 160-180° C., 8-10 MPa, and maintaining pressure for 10-20 minutes.

3. The bipolar plate according to claim 1, characterized in that The bipolar plates are recyclable. The scrapped bipolar plates are crushed and dissolved in a mixed solvent of hydrochloric acid and tetrahydrofuran. The mixture is stirred at 50-60° C. for 60-90 minutes, and the resin containing dynamic imine bonds is decomposed again into compounds with amino and aldehyde end groups. The hydrochloric acid concentration is 0.1 mol / L, and the volume ratio of hydrochloric acid to tetrahydrofuran in the mixed solvent is 2:

8.

4. The bipolar plate according to claim 1, characterized in that The structural formula of the resin containing dynamic imine bond is as follows: ； Wherein, R1 is H or -OCH3; R2 is 、 、 、 、 One of the following; n in is 2, 4, 5, 6; The n in is 2, 4, 5, or 6.

5. The bipolar plate according to claim 1, characterized in that The preparation method of the resin containing dynamic imine bond is as follows: Step (1), mixing the monomer containing aldehyde groups and hydroxyl groups and the diamine compound in ethanol, wherein the molar ratio of the monomer containing aldehyde groups and hydroxyl groups to the diamine compound is 2:1, heating the mixture at 50-100° C. for 2-6 hours, and removing the ethanol by concentration to obtain the corresponding monomer; Step (2): dissolving the monomer prepared in step (1) in ethanol, adding 2-4 times the molar amount of epichlorohydrin and 1000-5000 ppm of tetrabutylammonium bromide to the monomer, heating to 80-100° C., reacting for 1-2 hours, and then adding excess NaOH to terminate the reaction. After cooling to room temperature, extraction is performed using dichloromethane. After the extraction is completed and the solvent is evaporated, a resin matrix containing dynamic imine bonds can be obtained.

6. The bipolar plate according to claim 1, characterized in that The curing agent used is one of the following structures: 。 7. The bipolar plate according to claim 1, characterized in that The conductive filler is one of graphite powder, carbon fiber powder, acetylene black, carbon nanotubes, carbon black, graphene, metal-modified nickel-coated graphite powder, and metal-modified nickel-coated carbon nanotubes; The reinforcing conductive fiber is one of carbon fiber, nickel-plated carbon fiber, and silver-plated carbon fiber, with a fiber length of 3-5 cm, a fiber diameter of 6-12 μm, and a fiber conductivity of 10 4 -10 6 S / m; The conductive filler interface modifier is BYK-C8013, and the dispersant is BKY-W9010.

8. The bipolar plate according to claim 1, characterized in that The content of each raw material in the bulk molding compound is as follows: Resin: 17wt~22wt% Curing agent: 2wt~5wt%; Conductive filler: 10wt~25wt%; Reinforced conductive fiber: 45wt~60wt%; Functional additives: 1wt~2wt%.

9. The method for preparing a bipolar plate according to any one of claims 1 to 8, characterized in that Here are the steps: S1. Weigh the conductive filler and vigorously stir and disperse it with a high-speed shear mixer for 5-10 minutes at a stirring speed of 4000-12000 rpm. Then add the interfacial modifier and dispersant and continue stirring for 10 minutes to obtain a powder; S2, adding the powder and resin that are uniformly dispersed by stirring into a kneader or planetary mixer according to the proportion and further mixing, the kneading temperature is less than 65 ° C, the mixing time is 30-50 min, and a premixed slurry is obtained; S3. Add the premixed slurry into a Z-type reamer mixer or a planetary mixer, add the dried reinforced conductive fiber, stir for 10-15 minutes, then pour out the mass, stirring at a speed of 4000-12000 rpm; S4, pouring the mass material into the extruder storage bin, and squeezing the mass material to the molding port through the rotation of the screw of the extrusion system, and shaping it through the molding port to obtain a mass molding compound; S5. Using the prepared bulk molding compound to directly form bipolar plates by one-step hot pressing, the mold temperature is 100-160°C, the molding pressure is 10-20 MPa, and the holding time is 10-20 min; S6. After the pressure holding is completed, the mold is opened to take out the formed bipolar plate and remove the burrs.

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