A method for preparing a fast-curing expanded graphite-based fuel cell composite bipolar plate

Abstract

The present invention discloses a method for preparing a fast-curing expanded graphite-based fuel cell composite bipolar plate. The method involves cutting a three-dimensional soft-cut carbon fiber foam into the size of a bipolar plate, immersing it in liquid resin for 10 to 30 minutes, and drying it in a vacuum drying oven at 25 to 40°C. Pre-cold-pressed expanded graphite, serving as the top and bottom layers of the bipolar plate, is placed into a mold at 10 to 15 MPa. The soft-cut carbon fiber foam resin is placed in the middle layer. The mold is heated to 90 to 150°C at 10 to 15 MPa and maintained for 110 seconds to 58 minutes before demolding to obtain the fuel cell composite bipolar plate. The hot pressing method is simple, and the prepared bipolar plate exhibits a planar conductivity of 375.8 S / cm, a maximum bending pressure of 88.53 N, a bending strength of 61 MPa, and an airtightness of 2.32×10 ‑8 cm 3 cm 2 s ‑1 , water contact angle is 92°, corrosion resistance current is 0.345μA / cm 2 , which can realize large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a method for preparing a fast-curing expanded graphite-based fuel cell composite bipolar plate. Background Art

[0002] Fuel cell bipolar plates, as key components of fuel cell stacks, are responsible for distributing reactant gases, collecting current, transferring heat, and providing mechanical support. First, composite bipolar plates must possess excellent electrical and thermal conductivity to ensure efficient electrochemical reactions and the timely dissipation of reaction heat. Second, composite bipolar plates must possess excellent corrosion resistance and mechanical strength to maintain stability in the harsh operating environment of fuel cells. Furthermore, composite bipolar plates must possess excellent gas sealing properties to prevent mixing and leakage of reactant gases.

[0003] Expanded graphite, with its excellent electrical and thermal conductivity, is an ideal substrate for fuel cell bipolar plates. Currently, expanded graphite-based composite bipolar plates are prepared by mixing graphite and resin using a dry or wet process, followed by curing and compression molding. To achieve high flexural strength and airtightness, the liquid resin typically requires the addition of a curing agent and accelerator, resulting in a long curing time. The shrinkage and deformation of the graphite and liquid resin composite material during the 2-4 hours of curing affects the bipolar plate's dimensional accuracy, surface quality, mechanical strength, and service life. Differences in density and particle size between the graphite and resin lead to uneven dispersion of the graphite in the resin, impacting the bipolar plate's electrical and thermal conductivity.

[0004] The patent, publication number CN116995259A, is titled "A fuel cell composite bipolar plate and its preparation method." Melamine foam is activated, a nickel plating solution containing 0.3-6% nickel chloride, 0.2-4% sodium citrate, 0.5-10% ammonia water, and 80-95% deionized water is prepared, the activated melamine foam is nickel-plated, graphite material is evenly laid in a mold, and a first pre-pressing at 1-10 MPa is performed to obtain a bottom graphite plate. Nickel-plated melamine foam is laid on the bottom graphite plate, and graphite material is evenly laid on the upper surface. The plate is cold-pressed and placed in a vacuum impregnation tank, where vacuum is applied and maintained for 0.5-2 hours. Then, a thermosetting resin is absorbed and impregnated at a pressure of 0.01-0.5 MPa for 1-20 hours. The plate is then cured in an oven at 100-180°C for 1-5 hours to produce the composite bipolar plate. This method requires that the melamine foam be electroplated, which is a complex process. The thermosetting resin is absorbed and pressurized to 0.01-0.5 MPa, immersed for 1-20 hours, and then cured in an oven at 100-180°C for 1-5 hours. The long curing time affects the electrical conductivity, thermal conductivity, dimensional accuracy, surface quality, mechanical strength and service life of the bipolar plate. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the prior art and provide a method for preparing a fast-curing expanded graphite-based fuel cell composite bipolar plate that is simple in preparation, shortens the production cycle through rapid curing, coordinates the conductivity and mechanical strength of the composite bipolar plate, and controls the dimensional accuracy of the bipolar plate.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0007] (1) Preparation of soft-cut carbon fiber foam: Cut the three-dimensional soft-cut carbon fiber foam into the size of bipolar plates;

[0008] (2) Prepare liquid resin: dissolve solid resin in acetone at a mass ratio of 1:4, wherein the solid resin is any one of vinyl ester resin, compounded epoxy resin, and polysulfone resin;

[0009] (3) Preparing soft-cut carbon fiber foam resin: immersing the soft-cut carbon fiber foam described in step (1) in the liquid resin described in step (2) for 10 to 30 minutes, and drying in a vacuum drying oven at 25 to 40°C;

[0010] (4) Pre-cold-pressing expanded graphite at 10-15 MPa as the top and bottom layers of the bipolar plate, wherein the mass fractions of the expanded graphite in the top and bottom layers of the bipolar plate are equal;

[0011] (5) First, place the bottom layer of the bipolar plate described in step (4) into the mold, then place the soft-cut carbon fiber foam resin described in step (3) on the middle layer, and finally place the top layer of the bipolar plate described in step (4) into the mold, heat it to 90~150℃ under a pressure of 10~15Mpa and keep it for 110 seconds~58 minutes. After the temperature cools down, demould to obtain a fuel cell composite bipolar plate.

[0012] Furthermore, the soft-cut carbon fiber foam of the present invention accounts for 15-45% of the total mass fraction of the bipolar plate.

[0013] Furthermore, the mass fraction ratio of the soft cut carbon fiber foam to the liquid resin of the present invention is 1:1.

[0014] Furthermore, the expanded graphite of the present invention is flake graphite powder, graphite sheet, or a combination of both.

[0015] Beneficial effects of the present invention:

[0016] The soft-cut carbon fiber foam used in the present invention has a rough surface and a uniform three-dimensional void network, which can effectively absorb liquid resin. Under the action of pressure, the soft-cut carbon fiber foam becomes short fibers and liquid resin (the liquid resin is obtained by dissolving a solid resin with a viscosity of 9000cps in acetone at a mass ratio of 1:4). The rapid solidification shortens the solidification time, improves the dimensional accuracy and production efficiency of the bipolar plate, and coordinates the electrical conductivity, bending strength and air tightness. The "sandwich-type" sandwich structure of the present invention uses pre-cold-pressed expanded graphite at 10-15Mpa as the top and bottom layers of the bipolar plate to improve the electrical and thermal conductivity of the bipolar plate. The hot pressing molding preparation method of the present invention is simple and has high production efficiency. The prepared composite bipolar plate has a planar conductivity of 375.8S / cm, a maximum bending pressure of 88.53N, a bending strength of 61Mpa, and an air tightness of 2.32×10 - 8 cm 3 cm 2 s -1 , water contact angle is 92°, corrosion resistance current is 0.345μA / cm 2 , and can achieve large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is an electron microscope structure diagram of the soft-cut carbon fiber foam of the present invention;

[0018] Figure 2 This is an electron microscope structure diagram of the soft-cut carbon fiber foam resin of the present invention;

[0019] Figure 3 This is an electron microscope diagram of the cross-section of the composite bipolar plate prepared in Example 1 of the present invention;

[0020] Figure 4 This is a physical picture of the soft-cut carbon fiber foam of the present invention;

[0021] Figure 5 A physical picture of the solid vinyl ester used in the present invention;

[0022] Figure 6 The composite bipolar plate prepared in Example 1 of the present invention;

[0023] Figure 7 The composite bipolar plate prepared in Comparative Example 1;

[0024] Figure 8 The composite bipolar plate prepared in Comparative Example 2;

[0025] Figure 9 The composite bipolar plate prepared in Comparative Example 4;

[0026] Figure 10 This is the composite bipolar plate with flow channels prepared in Example 7 of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples within the scope of the present invention. Example 1

[0028] A method for preparing a fast-curing expanded graphite-based fuel cell composite bipolar plate comprises the following steps:

[0029] (1) Preparation of soft cut carbon fiber foam: Figure 1 The three-dimensional soft-cut carbon fiber foam of model VU-DJZ-3.5 (purchased from Hangzhou Wuken New Material Technology Co., Ltd.) is cut into bipolar plates with a size of 6.5×7 cm and a mass of 3 g.

[0030] (2) Preparation of liquid resin: Figure 5 3 g of the solid vinyl ester resin shown was dissolved in 15 ml of acetone, allowed to stand for 5 min, and then stirred for 5 min to completely dissolve the solid resin;

[0031] (3) Preparation of soft-cut carbon fiber foam resin: immerse 3g of the soft-cut carbon fiber foam described in step (1) into 3g of the liquid resin described in step (2), let it stand for 10 minutes, and dry it in a vacuum drying oven at 40°C for 2 hours to obtain a soft-cut carbon fiber foam resin as shown in FIG. Figure 2 As shown;

[0032] (4) Weigh 1.5 g of expanded graphite and pre-cold-press it into the top and bottom bipolar plates at 10 MPa;

[0033] (5) First, place the bottom layer of the bipolar plate described in step (4) into the mold, then place the soft-cut carbon fiber foam resin described in step (3) in the middle layer, and finally place the top layer of the bipolar plate described in step (4) into the mold, heat to 150°C under a pressure of 15 MPa, hold for 110 seconds, and after the temperature cools, demould to obtain a fuel cell composite bipolar plate with a thickness of 1.39 mm. Figure 3 、 Figure 6 As shown, the smooth surface of the composite bipolar plate is conducive to surface hydrophobicity and is also convenient for subsequent processing.

[0034] Example 2 The other preparation methods are the same as those in Example 1, except that in step (5), the plate is heated to 90°C under a pressure of 10 MPa and maintained for 58 minutes. After the temperature is cooled, the plate is demoulded to obtain a fuel cell composite bipolar plate with a thickness of 1.44 mm. Example 3

[0035] A method for preparing a fast-curing expanded graphite-based fuel cell composite bipolar plate comprises the following steps:

[0036] (1) Preparation of soft cut carbon fiber foam: Figure 4 The three-dimensional structure of the soft-cut carbon fiber foam shown is cut into bipolar plates with a size of 6.5 × 7 cm and a mass of 3 g;

[0037] (2) Preparation of liquid resin: Dissolve 3 g of commercially available solid-state epoxy resin, model MERICAN 3300 (produced by Huachang Polymer Co., Ltd., East China University of Science and Technology) in 15 ml of acetone, let it stand for 5 minutes, and then stir it slowly with a glass rod for 5 minutes to completely dissolve the solid resin;

[0038] (3) Preparing a soft-cut carbon fiber foam resin: immersing the soft-cut carbon fiber foam described in step (1) in the liquid resin described in step (2), allowing the mixture to stand for 30 minutes, and drying the mixture in a vacuum drying oven at 25° C. for 2 hours to obtain a soft-cut carbon fiber foam resin;

[0039] (4) Weigh 1.5 g of expanded graphite and pre-cold-press it into the top and bottom bipolar plates at 15 MPa;

[0040] (5) First, place the bottom layer of the bipolar plate described in step (4) into the mold, then place the soft-cut carbon fiber foam resin described in step (3) in the middle layer, and finally place the top layer of the bipolar plate described in step (4) into the mold, heat to 120°C under a pressure of 15 MPa, maintain for 2.5 minutes, and after the temperature cools down, demould to obtain a fuel cell composite bipolar plate with a thickness of 1.45 mm.

[0041] The other preparation methods of Example 4 are the same as those of Example 3, except that in step (5), the plate is heated to 100°C under a pressure of 10 MPa and maintained for 58 minutes. After the temperature is cooled, the plate is demoulded to obtain a fuel cell composite bipolar plate with a thickness of 1.43 mm. Example 5

[0042] A method for preparing a fast-curing expanded graphite-based fuel cell composite bipolar plate comprises the following steps:

[0043] (1) Preparation of soft-cut carbon fiber foam: Cut the three-dimensional soft-cut carbon fiber foam into bipolar plates with a size of 6.5×7 cm and a mass of 3 g;

[0044] (2) Preparation of liquid resin: Dissolve 3 g of solid polysulfone resin in 15 ml of acetone, let it stand for 5 minutes, and then stir it slowly with a glass rod for 5 minutes to completely dissolve the solid resin;

[0045] (3) Preparation of soft-cut carbon fiber foam resin: immerse the soft-cut carbon fiber foam described in step (1) in the liquid resin described in step (2), let it stand for 20 minutes, and dry it in a vacuum drying oven at 32°C for 2 hours to obtain soft-cut carbon fiber foam@resin;

[0046] (4) Weigh 1.5 g of expanded graphite and pre-cold-press it into the top and bottom layers of the bipolar plate at 12 MPa;

[0047] (5) First, place the bottom layer of the bipolar plate described in step (4) into the mold, then place the soft-cut carbon fiber foam resin described in step (3) in the middle layer, and finally place the top layer of the bipolar plate described in step (4) into the mold, heat to 130°C under a pressure of 15 MPa, maintain for 4 minutes, and after the temperature cools down, demould to obtain a fuel cell composite bipolar plate with a thickness of 1.46 mm.

[0048] Example 6 The other preparation methods are the same as those in Example 5, except that in step (5), the plate is heated to 100°C under a pressure of 15 MPa and maintained for 58 minutes. After the temperature is cooled, the plate is demoulded to obtain a fuel cell composite bipolar plate with a thickness of 1.47 mm. Example 7

[0049] A method for preparing a fast-curing expanded graphite-based fuel cell composite bipolar plate comprises the following steps:

[0050] (1) Preparation of soft-cut carbon fiber foam: Cut the three-dimensional soft-cut carbon fiber foam into bipolar plates with a size of 6.5×7 cm and a mass of 3.5 g;

[0051] (2) Preparation of liquid resin: Dissolve 3.5 g of solid vinyl ester resin in 17.5 ml of acetone, let it stand for 5 minutes, and then stir it slowly with a glass rod for 5 minutes to completely dissolve the solid resin;

[0052] (3) Preparing a soft-cut carbon fiber foam resin: immersing the soft-cut carbon fiber foam described in step (1) in the liquid resin described in step (2), allowing the mixture to stand for 10 minutes, and drying the mixture in a vacuum drying oven at 40° C. for 2 hours to obtain a soft-cut carbon fiber foam resin;

[0053] (4) Weigh 1.5 g of expanded graphite and pre-cold-press it into the top and bottom bipolar plates at 10 MPa;

[0054] (5) First, place the bottom layer of the bipolar plate described in step (4) into the mold, then place the soft-cut carbon fiber foam resin described in step (3) in the middle layer, and finally place the top layer of the bipolar plate described in step (4) into the mold, heat it to 140°C under a pressure of 15 MPa, keep it for 2 minutes and 30 seconds, and after the temperature cools down, demould it to obtain the following Figure 10 Fuel cell composite bipolar plate shown with a thickness of 1.45 mm. Comparative Example 1

[0055] A method for preparing a fuel cell composite bipolar plate comprises the following steps:

[0056] (1) 3 g of expanded graphite was placed in a 6.5 cm × 7 cm mold and cold pressed at a pressure of 15 MPa to obtain a pure expanded graphite sheet;

[0057] (2) Take 3g of solid vinyl ester resin in a beaker, take 15ml of acetone in a mass ratio of 1:4 in the beaker, let it stand for 5 minutes, and then stir slowly with a glass rod for 5 minutes to make the solid resin completely dissolved in acetone.

[0058] (3) Place the expanded graphite from step (1) in a culture dish, pour the liquid resin from step (2) into the culture dish, place the dish in a vacuum drying oven set to 40°C, evacuate for 5 minutes, and then keep it for 2 hours.

[0059] (4) Then, the temperature of the vacuum drying oven in step (3) was raised to 150°C and maintained for 110 seconds. After the temperature cooled, the plate was taken out to obtain a composite bipolar plate containing a fast-curing resin with a thickness of 1.23 mm, as shown in FIG. Figure 7 The surface of the composite plate shown is rough, and the resin is impregnated in the surface layer of the expanded graphite, which will cause its electrical conductivity to be greatly reduced and its brittleness to be unfavorable for subsequent processing. Comparative Example 2

[0060] A method for preparing a fuel cell composite bipolar plate comprises the following steps:

[0061] (1) Cut commercially available melamine foam with a thickness of 1.5 mm into 6.5 × 7 cm pieces.

[0062] (2) Take 3g of fast-curing solid vinyl ester resin in a beaker, take 15.0ml of acetone in a mass ratio of 1:4 in the beaker, let it stand for 5 minutes, and then stir slowly with a glass rod for 5 minutes to make the solid resin completely dissolved in acetone.

[0063] (3) Place the melamine foam prepared in step (1) in a culture dish, pour the liquid resin prepared in step (2) into the culture dish, let it stand for 10 minutes to allow it to be completely absorbed into the melamine foam, and then place it in a vacuum drying oven at 40°C for 2 hours.

[0064] (4) Two portions of 1.5 g expanded graphite were pre-cold pressed at 10 MPa as the top and bottom layers of the bipolar plate;

[0065] (5) First, place the bottom layer of the bipolar plate described in step (4) into the mold, then place the soft-cut carbon fiber foam resin described in step (3) in the middle layer, and finally place the top layer of the bipolar plate described in step (4) into the mold, heat it to 150°C under a pressure of 15 MPa, keep it for 110 seconds, and after the temperature cools down, demould it to obtain a fuel cell composite bipolar plate with a thickness of 1.35 mm. Figure 8As shown, the surface is relatively rough, which is not conducive to surface hydrophobicity and subsequent processing. Comparative Example 3

[0066] A method for preparing a fuel cell composite bipolar plate comprises the following steps:

[0067] (1) Preparation of soft-cut carbon fiber foam: Cut the three-dimensional soft-cut carbon fiber foam into bipolar plates with a size of 6.5×7 cm and a mass of 3 g;

[0068] (2) Preparation of resin: Add 1.5 g of curing agent 4,4′-diaminodiphenyl sulfone to 3 g of liquid epoxy impregnation resin (AG-80 quaternary functional epoxy resin, purchased from Shanghai Huayi Resin Co., Ltd.), mix and stir for 10 min;

[0069] (3) preparing a soft-cut carbon fiber foam resin: immersing the soft-cut carbon fiber foam described in step (1) in the epoxy impregnation resin described in step (2), allowing the mixture to stand for 10 minutes, and drying the mixture in a vacuum drying oven at 40° C. for 2 hours to obtain a soft-cut carbon fiber foam resin;

[0070] (4) Two portions of 1.5 g expanded graphite were pre-cold pressed at 10 MPa as the top and bottom layers of the bipolar plate;

[0071] (5) First, place the bottom expanded graphite that has been pre-cold pressed in step (4) into the mold, then place the soft-cut carbon fiber foam resin described in step (3) in the middle layer, and finally place the top expanded graphite that has been pre-cold pressed in step (4) into the mold, heat it to 150°C under a pressure of 15 MPa, keep it for 2 hours, and after the temperature cools down, demould to obtain a fuel cell composite bipolar plate with a thickness of 1.52 mm. Comparative Example 4

[0072] A method for preparing a fuel cell composite bipolar plate comprises the following steps:

[0073] The other preparation methods are the same as those in Example 1, except that the expanded graphite as the top and bottom layers of the bipolar plate is not subjected to the pre-cold pressing treatment in step (4) to obtain a fuel cell composite bipolar plate with a thickness of 1.48 mm. Figure 9 As shown, the surface is rough and the expanded graphite cannot be completely arranged on the surface of the plate, resulting in stratification, which is not conducive to hydrophobicity and subsequent processing.

[0074] The performance test results of the composite bipolar plates obtained in Examples 1-7 and Comparative Examples 1-4 are shown in Table 1:

[0075] (1) Bipolar plate bending strength test: The bending strength of the bipolar plate was tested using an electronic universal testing machine (Shimadzu, 33012) using the three-point bending method. The span of the test sample was 32 times the thickness to improve accuracy. The bending strength test samples were uniformly 60 mm in length, 10 mm in width, and 1.2-1.5 mm in thickness. The test speed was 2 mm / s, and the lower span was 45 mm.

[0076] (2) Area specific resistance is tested according to GB / T20042.6. The support layer is made of carbon paper used for fuel cell diffusion layer; the electrode is a metal-plated electrode, generally a gold-plated electrode;

[0077] (3) The electrical conductivity was tested using a four-probe resistivity tester (Keithley, 2400);

[0078] (4) Gas permeability is tested using a gas leak detector (AIRTEK, N50);

[0079] (5) The surface roughness was tested by an optical 3D surface profiler (WX-S100).

[0080] (6) Water contact angle measuring instrument (JC2000DS2B, Shanghai Zhongchen Digital Technology Equipment Co., Ltd.);

[0081] Corrosion resistance test:

[0082] (7) The electrochemical performance of the composite board was tested using an electrochemical workstation (Shanghai Chenhua CHI660E). A three-electrode system was used to test the electrochemical performance of the composite board. 2 The sample was used as the working electrode, the calomel electrode as the reference electrode, and the platinum sheet as the counter electrode. The Tafel plot was performed using 0.5 MH₂SO₄ as the electrolyte at 80°C and a scan rate of 2 mV / s to measure the corrosion current of the composite bipolar plate.

[0083] (8) Dimensional deviation was tested using a vernier caliper (Shanghai Measuring Tool Factory Co., Ltd. ISO9001).

[0084] Table 1 Performance test table of composite bipolar plates of Examples 1-7 and Comparative Examples 1-4

[0085]

[0086] As shown in Table 1, Comparative Example 1 is an expanded graphite impregnated with a fast-curing resin, which lacks the soft-cut carbon fiber foam as an intermediate medium. The bending strength, area specific resistance, corrosion resistance and gas permeability of the composite bipolar plate after impregnation cannot meet the application requirements (bending strength greater than 25 MPa, area specific resistance less than 10 mΩ·cm 2, gas permeability is less than 2.0×10-6cm 3 cm -2 s -1 , corrosion current is less than 1μA / cm 2 Comparative Example 2 utilizes an expanded graphite-melamine foam fast-curing resin composite bipolar plate. This uses melamine foam instead of soft-cut carbon fiber foam as the intermediate medium, allowing the resin to reside in the middle layer. This sandwich-type design improves conductivity and airtightness, but significantly reduces bending strength. In Comparative Example 3, the polymer is a liquid resin, as used in the prior art, requiring a longer curing time. This difference in polymer leads to differences in bipolar plate performance. While the overall performance meets application requirements, it still lags behind that of Example 1. Comparative Example 4 differs from Example 1 in that the expanded graphite in the bipolar plate surface layer is not pre-cold pressed. While both meet application requirements, the overall performance is inferior to that of Example 1. The present invention utilizes soft-cut carbon fiber foam and a fast-curing resin as an intermediate medium, which not only improves the bipolar plate's conductivity but also meets its bending strength requirements, enhancing airtightness and corrosion resistance. The use of expanded graphite as the outer layer effectively enhances the plate's conductivity, while the use of high-temperature, fast-curing epoxy resin as the polymer improves production efficiency and effectively controls dimensional accuracy, enabling large-scale industrial production. The "sandwich" structure design not only provides excellent hydrophobicity and corrosion resistance, but also balances the bipolar plate's conductivity, bending strength, and airtightness requirements. The present invention simplifies the preparation process and produces a composite bipolar plate with excellent overall performance.

[0087] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a fast-curing expanded graphite-based fuel cell composite bipolar plate, characterized in that: The steps include: (1) Preparation of soft-cut carbon fiber foam: Cut the three-dimensional soft-cut carbon fiber foam into the size of bipolar plates; (2) Prepare liquid resin: dissolve solid resin in acetone at a mass ratio of 1:4, wherein the solid resin is any one of vinyl ester resin, compounded epoxy resin, and polysulfone resin; (3) Preparing soft-cut carbon fiber foam resin: immersing the soft-cut carbon fiber foam described in step (1) in the liquid resin described in step (2) for 10 to 30 minutes, and drying in a vacuum drying oven at 25 to 40°C; (4) Pre-cold-pressing expanded graphite at 10-15 MPa as the top and bottom layers of the bipolar plate, wherein the mass fractions of the expanded graphite in the top and bottom layers of the bipolar plate are equal; (5) First, place the bottom layer of the bipolar plate described in step (4) into the mold, then place the soft-cut carbon fiber foam resin described in step (3) on the middle layer, and finally place the top layer of the bipolar plate described in step (4) into the mold, heat it to 90~150℃ under a pressure of 10~15Mpa and keep it for 110 seconds~58 minutes. After the temperature cools down, demould to obtain a fuel cell composite bipolar plate.

2. The method for preparing a fast-curing expanded graphite-based fuel cell composite bipolar plate according to claim 1, characterized in that: The soft-cut carbon fiber foam in step (1) accounts for 15-45% of the total mass of the bipolar plate.

3. The method for preparing a fast-curing expanded graphite-based fuel cell composite bipolar plate according to claim 1, characterized in that: The mass ratio of the soft-cut carbon fiber foam to the liquid resin in step (3) is 1:

1.

4. The method for preparing a fast-curing expanded graphite-based fuel cell composite bipolar plate according to any one of claims 1 to 3, characterized in that: The expanded graphite in step (4) is one or a combination of flake graphite powder and graphite flakes.

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