Composite molding process of multilayer flow battery bipolar plates

Abstract

This invention discloses a composite molding process for multilayer flow battery bipolar plates, comprising the following steps: placing metal foil in a punching machine for roll pressing and punching to obtain perforated metal foil; cleaning the perforated metal foil with alcohol, and stacking flexible graphite paper, perforated metal foil, and flexible graphite paper in a "sandwich" structure, and then rolling and pressing them to obtain a composite bipolar plate; subjecting the pressed composite bipolar plate to impregnation, cleaning, curing, and drying to obtain a multilayer flow battery bipolar plate. This invention provides a composite molding process for multilayer flow battery bipolar plates, using perforated metal foil as the interlayer and flexible graphite paper as the upper and lower layers, employing a punching process to construct a "sandwich" structure. This results in a multilayer flow battery bipolar plate with high bonding strength, avoiding delamination of the metal foil and flexible graphite paper, effectively improving the bending strength and conductivity of the multilayer flow battery bipolar plate, reducing its contact resistance, and constructing a better conductive network.

Description

Technical Field

[0001] This invention relates to the field of flow battery bipolar plate fabrication technology, and more particularly to the composite molding process of multilayer flow battery bipolar plates. Background Technology

[0002] A flow battery is an electrochemical energy storage device that utilizes separate positive and negative electrolytes for independent circulation. It is a high-performance battery characterized by high capacity, wide application range, and long cycle life, making it a popular new energy product widely used in new energy vehicles. The bipolar plate is a key component of a flow battery, used to connect and separate multiple cells, conduct current generated within the cells, and provide support for the reaction electrodes. Therefore, bipolar plates require good conductivity, high mechanical strength, considerable airtightness, and strong corrosion resistance.

[0003] Currently, bipolar plate materials mainly include graphite bipolar plates, graphite-based composite bipolar plates, and metal bipolar plates. Traditional flexible graphite bipolar plates are made from raw materials such as expanded graphite and sealing resin through pressing, impregnation, cleaning, and curing. Their bending strength is generally less than 30 MPa, making them only suitable for applications under low fluid pressure. Composite bipolar plates, on the other hand, combine the high electrical conductivity, thermal conductivity, and corrosion resistance of graphite materials with the high toughness of polymer materials. They have relatively low manufacturing costs and relatively good mechanical properties. Composite bipolar plates for flow batteries mainly include graphite-resin composite bipolar plates, graphite-ceramic composite bipolar plates, and graphite-metal composite bipolar plates. Among them, graphite-metal composite bipolar plates combine the advantages of both graphite and metal materials, exhibiting high electrical and thermal conductivity and corrosion resistance. They also have high mechanical strength and good density, making them considered to be very promising bipolar plates.

[0004] Traditional graphite-metal composite bipolar plates are manufactured by sandwiching a thin metal sheet between two layers of flexible graphite material, applying an adhesive layer, and then pressing, impregnating, cleaning, and curing. However, with long-term use, the adhesive is prone to aging and detachment, leading to delamination between the metal and flexible graphite materials, which is detrimental to the stability of the flow battery composite bipolar plate. Therefore, developing a novel composite molding process for multilayer flow battery bipolar plates that improves the bending strength and conductivity of the bipolar plate, reduces its contact resistance, and achieves a stable bond between the metal and graphite materials is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a composite molding process for multilayer flow battery bipolar plates. The multilayer flow battery bipolar plates made by this molding process have a high degree of bonding, which can avoid the delamination of metal foil and flexible graphite paper, achieve a stable bond between metal materials and graphite materials, effectively improve the bending strength, conductivity and corrosion resistance of multilayer flow battery bipolar plates, reduce their contact resistance, and facilitate the construction of a better conductive network.

[0006] To achieve the above objectives, the present invention provides a composite molding process for multilayer flow battery bipolar plates, comprising the following steps:

[0007] S1. Place the metal foil in a punching machine for roll pressing and punching to obtain perforated metal foil;

[0008] S2. Clean the perforated metal foil with alcohol, and stack the flexible graphite paper, perforated metal foil and flexible graphite paper in a "sandwich" structure. After being rolled by a roller press, a composite bipolar plate is obtained.

[0009] S3. The pressed composite bipolar plate is impregnated, cleaned, cured and dried to obtain a multilayer flow battery bipolar plate.

[0010] As a preferred embodiment, the perforated metal foil has a pore size of 0.5~2mm and a porosity of 10~20 pores / cm². 2 .

[0011] As a preferred embodiment, the contact resistance of the multilayer flow battery bipolar plate is ≤5.02mΩ·cm. 2 Electrical conductivity >300 S / cm, flexural strength >45 MPa.

[0012] As a preferred embodiment, the metal foil is one of stainless steel, titanium foil, and aluminum foil; the thickness of the metal foil is 0.05~0.3mm.

[0013] As a preferred embodiment, the thickness of the composite bipolar plate is 0.5~3mm.

[0014] As a preferred embodiment, the sprint machine has a power of 4kw and a speed of 25m / h.

[0015] As a preferred embodiment, the roll forming is room temperature roll forming.

[0016] As a preferred embodiment, the impregnation is a vacuum-pressure impregnation with a pressure of 2 MPa and a holding time of 32 h.

[0017] As a preferred embodiment, the impregnation procedure involves first evacuating to a vacuum level and then pressurizing. Within 1 hour, the vacuum level is first evacuated to 100 Pa and maintained for 30 minutes. Then, gas is introduced to increase the pressure to 2 MPa, and the final pressure is maintained constant for 32 hours.

[0018] As a preferred embodiment, the curing is performed by water bath curing at a temperature of 90-95°C for 25-40 minutes.

[0019] As a preferred embodiment, the drying is performed in an oven at a temperature of 100~120℃ for 1~3 hours.

[0020] Another aspect of the present invention provides a multilayer flow battery bipolar plate prepared by a composite molding process of the multilayer flow battery bipolar plate as described above.

[0021] As a preferred embodiment, the bending strength of the multilayer flow battery bipolar plate is 45.93~49.95 MPa.

[0022] As a preferred embodiment, the conductivity of the multilayer flow battery bipolar plate is 311~365 S / cm.

[0023] As a preferred embodiment, the contact resistance of the multilayer flow battery bipolar plate is 4.69~5.02 mΩ·cm. 2 .

[0024] The present invention also provides an application of the multilayer flow battery bipolar plate described above in a flow battery.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention utilizes roll forming to form perforated metal foil, and uses perforated metal foil as sandwich and flexible graphite paper as upper and lower layers to construct a "sandwich" stacked structure, so that graphite is embedded in the micropores of the metal surface, thereby making the resulting multilayer flow battery bipolar plate highly bonded, avoiding the delamination of metal foil and flexible graphite paper, realizing the stable bonding of metal materials and graphite materials, effectively improving the bending strength, conductivity and corrosion resistance of multilayer flow battery bipolar plate, reducing its contact resistance, which is beneficial to reduce ohmic polarization loss, improve the overall efficiency of the battery and the conductivity of the bipolar plate, and construct a better conductive network.

[0027] (2) The composite molding process for the multilayer flow battery bipolar plate proposed in this invention is simple and practical. The multilayer flow battery bipolar plate prepared using this process has high bending strength, reaching 45.93~49.95 MPa, good conductivity, with a conductivity as high as 311~365 S / cm, and low resistivity, with a contact resistance of 4.69~5.02 mΩ·cm. 2 . Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] This embodiment discloses a composite molding process for multilayer flow battery bipolar plates, including the following steps:

[0030] S1. Place a metal foil with a thickness of 0.05~0.3mm into a punching machine for roll punching to obtain a perforated metal foil;

[0031] S2. Clean the perforated metal foil with alcohol, and stack the flexible graphite paper, perforated metal foil and flexible graphite paper in a "sandwich" structure. After being rolled by a roller press at room temperature, a composite bipolar plate with a thickness of 0.5~3mm is obtained.

[0032] S3. The pressed composite bipolar plate is impregnated, cleaned, cured in a water bath and dried to obtain a multilayer flow battery bipolar plate.

[0033] The perforated metal foil has a pore size of 0.5~2mm and a porosity of 10~20 pores / cm². 2 .

[0034] Roll forming and punching is a composite process for manufacturing metal-graphite bipolar plates, combining punching and roll forming. It involves creating a regular array of through holes in a metal foil (such as titanium or stainless steel) through precision punching, followed by roll forming to embed flexible graphite material into these holes, forming a composite structure integrating mechanical interlocking and a conductive network. This process is a physical composite method and one of the key processes in preparing graphite-metal composite bipolar plates. It is primarily used to form a regular hole structure on the metal foil to enhance the mechanical interlocking and conductive connection with the graphite layer.

[0035] Room temperature roll forming is a plastic forming process that uses multiple rollers to continuously bend metal strips such as steel, aluminum, and copper into specific cross-sectional shapes at room temperature, i.e., 20~30℃. This forming process does not require heating and relies directly on mechanical force to complete the deformation. It has advantages such as energy saving, no surface oxidation, and high production efficiency, and is widely used in construction, automobile manufacturing, home appliances and other fields.

[0036] Impregnation, also known as immersion, is a micropore or crevic penetration sealing process. The sealing medium, usually a low-viscosity liquid, is penetrated into the micropores or crevices through methods such as natural permeation, vacuuming, and pressurization to fill the gaps. Then, the sealing medium in the gaps is cured by methods such as room temperature, cooling, or heating to achieve the effect of sealing the gaps.

[0037] Water bath curing is a process that uses water bath heating to cure materials. It is often used in situations where uniform heating and temperature control are required to ensure that the material does not experience localized overheating or uneven curing during the curing process. It is commonly used for a variety of materials, such as resins and coatings. Through the heat conduction effect of the water bath, the monomers and oligomers in the material react to form a three-dimensional polymer network, thereby achieving curing.

[0038] The drying process, also known as oven drying, is a process that uses electric heating, gas heating, or infrared heating to dehydrate / cur materials at a constant temperature in a sealed chamber. It is widely used in industrial, scientific research, and food processing fields. Its core features are high temperature controllability (±1~5℃) and uniform hot air circulation.

[0039] The impregnation process involves vacuum-pressurized impregnation. First, a vacuum of 100 Pa is drawn and maintained for 30 minutes. Then, gas is introduced and pressurized to 2 MPa, maintaining this final pressure for 32 hours. During the roll forming process of the multilayer flow battery bipolar plate, micron-level pores easily form at the interface between the flexible graphite and the metal foil. In the impregnation stage, the gas in the impregnation liquid (such as resin or silicate) is removed by vacuuming to prevent gas from seeping into the micropore defects of the multilayer flow battery bipolar plate and affecting its sealing performance. Simultaneously, under vacuum and pressurized conditions, the impregnation liquid can penetrate deep into the micropore defects of the multilayer flow battery bipolar plate, filling these pores and preventing electrolyte penetration that could lead to short circuits. This significantly reduces the porosity of the multilayer flow battery bipolar plate. Furthermore, the curing of the impregnating agent within the pores enhances the mechanical strength of the graphite-metal interface, significantly improving the flexural strength of the multilayer flow battery bipolar plate.

[0040] Water bath curing is a staged water bath heating reaction. First, the water is preheated at a low temperature, then the temperature is raised to a set temperature of 90-95℃ and held for 25-40 minutes, maintaining a stable water temperature. Using water bath heating ensures uniform heating and provides a constant temperature environment, ensuring temperature stability during the curing process of the multilayer flow battery bipolar plate.

[0041] Oven drying involves laying the multilayer flow battery bipolar plates flat on a tray and placing it in an electrically heated oven with a controlled airflow. The temperature is raised to a set level of 100-120°C, and the plates are dried for 1-3 hours. After drying, the heating is turned off, and the plates are allowed to cool naturally to below 60°C before being removed. Oven drying allows for precise control of the bipolar plate drying temperature, and the hot air circulation ensures uniform drying temperature, preventing localized overheating of the multilayer flow battery bipolar plates and achieving efficient dehydration.

[0042] This embodiment also provides a flow battery, which includes a multilayer flow battery bipolar plate prepared by the above-mentioned composite molding process of multilayer flow battery bipolar plates. Through process improvement, the strength, conductivity and other parameters of the flow battery are improved, thereby improving the safety, charging efficiency and other performance of new energy vehicles.

[0043] Example 1:

[0044] The composite molding process for multilayer flow battery bipolar plates includes the following steps:

[0045] S1. Place the metal foil in a punching machine for roll pressing and punching to obtain perforated metal foil;

[0046] S2. Clean the perforated metal foil with alcohol, and stack the flexible graphite paper, the perforated metal foil with a thickness of 0.1 mm and the flexible graphite paper in a "sandwich" structure. After being rolled by a roller press at room temperature, a composite bipolar plate with a thickness of 1 mm is obtained.

[0047] S3. The pressed composite bipolar plate is vacuum-pressurized and impregnated. After holding the pressure for 32 hours, the surface is cleaned and then cured in a water bath at 92°C for 30 minutes. Finally, it is dried in an oven at 120°C for 2 hours to obtain a multilayer flow battery bipolar plate.

[0048] The perforated metal foil has a pore size of 1.2 mm and a porosity of 16 pores / cm². 2 .

[0049] Example 2:

[0050] The composite molding process for multilayer flow battery bipolar plates includes the following steps:

[0051] S1. Place the metal foil in a punching machine for roll pressing and punching to obtain perforated metal foil;

[0052] S2. Clean the perforated metal foil with alcohol, and stack the flexible graphite paper, the perforated metal foil with a thickness of 0.1 mm and the flexible graphite paper in a "sandwich" structure. After being rolled by a roller press at room temperature, a composite bipolar plate with a thickness of 2 mm is obtained.

[0053] S3. The pressed composite bipolar plate is vacuum-pressurized and impregnated. After holding the pressure for 32 hours, the surface is cleaned and then cured in a water bath at 92°C for 30 minutes. Finally, it is dried in an oven at 120°C for 2 hours to obtain a multilayer flow battery bipolar plate.

[0054] The perforated metal foil has a pore size of 1.2 mm and a porosity of 16 pores / cm². 2 .

[0055] The difference between Example 2 and Example 1 is that the thickness of the composite bipolar plate after room temperature roll forming is increased to 2 mm.

[0056] Example 3:

[0057] The composite molding process for multilayer flow battery bipolar plates includes the following steps:

[0058] S1. Place the metal foil in a punching machine for roll pressing and punching to obtain perforated metal foil;

[0059] S2. Clean the perforated metal foil with alcohol, and stack the flexible graphite paper, the perforated metal foil with a thickness of 0.1mm and the flexible graphite paper in a "sandwich" structure. After being rolled by a roller press at room temperature, a composite bipolar plate with a thickness of 3mm is obtained.

[0060] S3. The pressed composite bipolar plate is vacuum-pressurized and impregnated. After holding the pressure for 32 hours, the surface is cleaned and then cured in a water bath at 92°C for 30 minutes. Finally, it is dried in an oven at 120°C for 2 hours to obtain a multilayer flow battery bipolar plate.

[0061] The perforated metal foil has a pore size of 1.2 mm and a porosity of 16 pores / cm². 2 .

[0062] The difference between Example 3 and Examples 1 and 2 is that the thickness of the composite bipolar plate after room temperature roll forming is increased to 3 mm.

[0063] Example 4:

[0064] The composite molding process for multilayer flow battery bipolar plates includes the following steps:

[0065] S1. Place the metal foil in a punching machine for roll pressing and punching to obtain perforated metal foil;

[0066] S2. Clean the perforated metal foil with alcohol, and stack the flexible graphite paper, the perforated metal foil with a thickness of 0.05mm and the flexible graphite paper in a "sandwich" structure. After being rolled by a roller press at room temperature, a composite bipolar plate with a thickness of 1mm is obtained.

[0067] S3. The pressed composite bipolar plate is vacuum-pressurized and impregnated. After holding the pressure for 32 hours, the surface is cleaned and then cured in a water bath at 92°C for 30 minutes. Finally, it is dried in an oven at 120°C for 2 hours to obtain a multilayer flow battery bipolar plate.

[0068] The perforated metal foil has a pore size of 1.2 mm and a porosity of 16 pores / cm². 2 .

[0069] The difference between Example 4 and Example 1 is that the thickness of the perforated metal foil is reduced to 0.05 mm. Compared with Examples 2 and 3, in addition to the thickness of the perforated metal foil being reduced to 0.05 mm, the thickness of the composite bipolar plate is also reduced to 1 mm.

[0070] Example 5:

[0071] The composite molding process for multilayer flow battery bipolar plates includes the following steps:

[0072] S1. Place the metal foil in a punching machine for roll pressing and punching to obtain perforated metal foil;

[0073] S2. Clean the perforated metal foil with alcohol, and stack the flexible graphite paper, the perforated metal foil with a thickness of 0.2 mm and the flexible graphite paper in a "sandwich" structure. After being rolled by a roller press at room temperature, a composite bipolar plate with a thickness of 1 mm is obtained.

[0074] S3. The pressed composite bipolar plate is vacuum-pressurized and impregnated. After holding the pressure for 32 hours, the surface is cleaned and then cured in a water bath at 92°C for 30 minutes. Finally, it is dried in an oven at 120°C for 2 hours to obtain a multilayer flow battery bipolar plate.

[0075] The perforated metal foil has a pore size of 1.2 mm and a porosity of 16 pores / cm². 2 .

[0076] The difference between Example 5 and Examples 1 and 4 is that the thickness of the perforated metal foil is increased to 0.2 mm, while compared with Examples 2 and 3, except that the thickness of the perforated metal foil is increased to 0.2 mm, the thickness of the composite bipolar plate is reduced to 1 mm.

[0077] Performance testing

[0078] The following performance tests were performed on the multilayer flow battery bipolar plates prepared in Examples 1-5 of this invention.

[0079] Test Example 1: Bending Strength Test

[0080] The bending strength of the multilayer flow battery bipolar plate was determined using a universal testing machine. 60×25mm specimens were cut from the middle portion of the multilayer flow battery bipolar plates prepared in Examples 1-5 using wire cutting. Three specimens were cut from each example's multilayer flow battery bipolar plate sample, with a span of 40mm. The bending strength of the multilayer flow battery bipolar plate was tested using the three-point bending method. The test steps are as follows:

[0081] (1) The multilayer flow battery bipolar plate sample was made into a long strip with a width of 25 mm;

[0082] (2) Adjust the span of the support so that the pressure head and the support head are both perpendicular to the sample axis;

[0083] (3) The pressure head moves at 5 mm / s 2 The load is applied at a uniform and non-impact rate until the sample breaks, and the breaking load value is read.

[0084] The flexural strength is calculated using the following formula:

[0085]

[0086] in, d F The strength is the bending strength, expressed in MPa.

[0087] P This is the breaking load value, in N;

[0088] L The span of the support is in mm.

[0089] b The width of the bipolar plate sample in a multilayer flow battery is shown in mm.

[0090] h The thickness of the bipolar plate sample in a multilayer flow battery is shown in mm.

[0091] Three valid test samples were taken as a group, and the average value was calculated as the test result. The test results are shown in Table 1.

[0092] Test Example 2: Conductivity Test

[0093] The conductivity of the bipolar plates in a multilayer flow battery was tested using a four-probe resistance meter. The experimental procedure is as follows:

[0094] (1) Sample pretreatment: The surface of the multilayer flow battery bipolar plate sample was ultrasonically cleaned with ethanol for 10 min each time to remove the surface oxide layer and grease. After drying, the thickness was measured at 5 points at the four corners and the center of the multilayer flow battery bipolar plate sample using a micrometer, and the average value was taken.

[0095] (2) Resistance measurement: Press the probe of the linear four-probe instrument vertically into the surface of the multilayer flow battery bipolar plate sample and read the resistance value R (unit Ω).

[0096] Electrical conductivity is calculated using the following formula:

[0097]

[0098] in, s Electrical conductivity, expressed in S / cm;

[0099] dThe thickness of the bipolar plate sample in a multilayer flow battery is shown in cm.

[0100] R The resistance of the bipolar plate in a multilayer flow battery is expressed in Ω.

[0101] A The effective flow-guiding area covered by the probe, in cm². 2 .

[0102] Five different regions were measured for each bipolar plate sample. After removing outliers, the average value was taken as the test result. The test results are shown in Table 1.

[0103] Test Example 3: Contact Resistance Test

[0104] The contact resistance of the bipolar plates in a multilayer flow battery was tested using a contact resistance meter. The test steps are as follows:

[0105] (1) Sample preparation: Select a sample with a size of 3cm × 3cm and an area of ​​9cm². 2 Five square multilayer flow battery bipolar plate samples should be provided, and they should be free of wrinkles, scratches, and damage.

[0106] (2) Contact Resistance Test: The multilayer flow battery bipolar plate was mounted on the test device, and the resistance value was measured using a low-resistance meter. The measuring electrode was a gold-plated copper electrode. During the measurement, carbon paper used for the diffusion layer of the fuel cell was placed on both sides of the sample as a support to further improve the contact condition. During the test, a resistance value was recorded for every 0.1 MPa increase in pressure until the rate of change between the current resistance value and the previous resistance value was ≤5%, at which point the minimum resistance value was considered to have been reached, and the test was stopped. The resistance value under different pressures is R1.

[0107] Contact resistance is calculated using the following formula:

[0108]

[0109] in, R The contact resistance between the bipolar plates and the carbon paper in a multilayer flow battery is expressed in mΩ.

[0110] R 1 represents the sum of the body resistance of the bipolar plate material of the multilayer flow battery, the body resistance of the carbon paper, the contact resistance between the two multilayer flow battery bipolar plates and the carbon paper, the body resistance of the two copper electrodes, and the contact resistance between the two carbon papers and the copper electrodes, in mΩ.

[0111] R 2 represents the sum of the resistance of the two copper electrodes, the resistance of the carbon paper, and the contact resistance between the two carbon papers and the copper electrodes, in mΩ.

[0112] RBP The bulk resistance of the bipolar plate material in a multilayer flow battery is expressed in mΩ.

[0113] R CP The resistance of the carbon paper is expressed in mΩ.

[0114] Three samples were taken as a group, and the average value was calculated as the test result. The test results are shown in Table 1.

[0115] Table 1

[0116]

[0117] As shown in Table 1, the multilayer flow battery bipolar plates of Examples 1-5, prepared by the composite molding process of the multilayer flow battery bipolar plates provided by this invention, exhibit excellent performance indicators, with bending strength reaching 45.93~49.95 MPa, conductivity of 311~365 S / cm, and contact resistance of 4.69~5.02 mΩ·cm. 2 .

[0118] As can be seen, the composite molding process of the multilayer flow battery bipolar plate proposed in this invention enables graphite to be highly embedded in the micropores of the metal surface (with barbs on the edges), which greatly improves the bonding force between the metal foil and the flexible graphite paper, leverages the high mechanical strength of the metal material, effectively improves the bending strength of the multilayer flow battery bipolar plate, and uses the flexible graphite paper as the outer layer of the "sandwich" stacked structure to effectively leverage the corrosion resistance of the graphite material, enhancing the corrosion resistance of the multilayer flow battery bipolar plate. At the same time, combining the high electrical and thermal conductivity of graphite and metal materials, the conductivity of the bipolar plate is significantly improved and its resistivity is reduced, which has great practical value.

[0119] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A composite molding process for multilayer flow battery bipolar plates, characterized in that, Includes the following steps: S1. Place the metal foil in a punching machine for roll pressing and punching to obtain perforated metal foil; S2. Clean the perforated metal foil with alcohol, and stack the flexible graphite paper, perforated metal foil and flexible graphite paper in a "sandwich" structure. After being rolled by a roller press, a composite bipolar plate is obtained. S3. The pressed composite bipolar plate is impregnated, cleaned, cured and dried to obtain a multilayer flow battery bipolar plate. The metal foil has a thickness of 0.2 mm. The perforated metal foil has a pore size of 1.2 mm and a porosity of 16 pores / cm². 2 ; The roll forming is a room temperature roll forming; The thickness of the composite bipolar plate is 1 mm; The impregnation is a vacuum-pressurized impregnation. The specific steps are as follows: within 1 hour, first evacuate to 100 Pa, let stand for 30 minutes, maintain the vacuum, introduce gas to pressurize, increase the pressure to 2 MPa, maintain the final pressure unchanged, and hold the pressure for 32 hours. The curing process is water bath curing, with a curing temperature of 92℃ and a curing time of 30 minutes; The drying process is carried out in an oven at a temperature of 120°C for 2 hours. The contact resistance of the bipolar plates in the multilayer flow battery is 4.69 mΩ·cm. 2 Its electrical conductivity is 365 S / cm, and its flexural strength is 49.95 MPa; The perforated metal foil has barbs along the edges of the perforated holes.

2. The composite molding process for the multilayer flow battery bipolar plate according to claim 1, characterized in that, The metal foil is one of stainless steel, titanium foil, and aluminum foil.

3. The composite molding process for the multilayer flow battery bipolar plate according to claim 1, characterized in that, The sprint machine has a power of 4kw and a speed of 25m / h.

4. A multilayer flow battery bipolar plate, characterized in that, It is prepared using the composite molding process of the multilayer flow battery bipolar plate as described in any one of claims 1-3.

5. The application of the multilayer flow battery bipolar plate as described in claim 4 in a flow battery.

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