Integrated current collecting assembly and preparation method and application thereof

Abstract

The application relates to the technical field of all-vanadium redox flow batteries, and discloses an integrated current collection assembly and a preparation method and application thereof, wherein a carbon nanotube / dimethylsiloxane / epoxy resin flexible conductive interface layer is prepared by introducing a functional hyperbranched polymer; the epoxy resin serves as a conductive interface layer matrix and has strong adhesive action; when cured, the epoxy resin firmly bonds the bipolar plate and the copper plate, reduces the contact resistance, and makes the conductive interface layer have certain flexibility; after assembly, the bipolar plate and the copper plate have good sealing between each other; the copper plate is prevented from being oxidized by air after long-term charging and discharging; the functional hyperbranched polymer can in-situ modify the carbon nanotube through CH-pi action, and the end of the functional hyperbranched polymer contains an epoxy group and a siloxane group; the dispersivity of the carbon nanotube is improved, the compatibility between the dimethylsiloxane and the epoxy resin is increased, and therefore the performance of the all-vanadium redox flow battery is improved.

Description

Technical Field

[0001] This invention belongs to the field of vanadium redox flow battery technology, specifically relating to an integrated current collector assembly, its preparation method, and its application. Background Technology

[0002] Vanadium redox flow batteries (VRBs) have become a key technology for large-scale, long-duration energy storage systems due to their advantages such as decoupling of energy storage capacity and power, long cycle life, high safety, and environmental friendliness. In the stack structure, copper plates and bipolar plates are two key materials affecting battery efficiency, cost, and reliability. Copper plates are responsible for collecting current and conducting it to the internal and external circuits, requiring high conductivity and typically being copper-based materials. Bipolar plates, on the other hand, function as electrolyte separators, electrode supports, and charge conductors, requiring conductivity, corrosion resistance, and mechanical strength. In practical operation, external current is first conducted through the copper plates to the bipolar plates, which then transfer charge to the electrodes, forming a charging path. The discharging process is the reverse. Therefore, the conductivity of the copper plates and bipolar plates themselves is a major factor affecting battery performance. However, with the rapid development of the VRB industry, the conductivity of bipolar plate materials has reached a certain level. Further improving conductivity often comes with high costs. Therefore, examining the structure and assembly process of copper plates and bipolar plates has become a new focus for improving the performance of VRBs.

[0003] Existing battery stack technologies generally employ a split design, where the copper plate and bipolar plate are assembled independently. During installation, the copper plate and bipolar plate are connected by physical pressing. Since both the copper plate and bipolar plate have a certain mechanical strength, the interface is a hard-hard contact, inevitably resulting in micro-gaps. This leads to a large contact resistance between the bipolar plate and the copper plate, exacerbating ohmic losses. On the other hand, air may enter through these micro-gaps, causing a certain degree of oxidation in the copper plate and reducing the energy efficiency and voltage efficiency of the vanadium redox flow battery. Therefore, designing a low-cost conductive interface layer with a certain degree of flexibility and adhesion to better seal between the copper plate and bipolar plate, increase the conductive area, and reduce battery losses has become one of the problems that need to be solved. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention provides an integrated current collector assembly, its preparation method, and its application. By preparing a flexible conductive interface layer of carbon nanotubes / polydimethylsiloxane / epoxy resin to form an integrated current collector assembly, the contact resistance is reduced, and the voltage efficiency and energy efficiency of the vanadium redox flow battery are improved.

[0005] The present invention adopts the following technical solution:

[0006] In the first aspect, a method for fabricating an integrated current collector component is disclosed, comprising the following steps:

[0007] Step S1: Add the catalyst, epoxy group-containing monomer, and siloxane monomer to an anhydrous solvent, introduce ethylene, and carry out the reaction. After post-treatment, functional hyperbranched polymer is obtained.

[0008] Step S2: The functional hyperbranched polymer, carbon nanotubes, polydimethylsiloxane, curing agent A, epoxy resin, and curing agent B are loaded into a ball mill jar and ball-milled to obtain a mixture.

[0009] Step S3: The mixture is uniformly coated onto one side of the bipolar plate, and a copper plate is attached to the surface coated with the mixture. A flexible conductive interface layer is formed by hot pressing. After complete curing, an integrated current collector is obtained.

[0010] In one implementation, in step S1:

[0011] The mass ratio of the catalyst, epoxy group-containing monomer, siloxane monomer and anhydrous solvent is 0.25:(2~4):(2~4):(20~40).

[0012] In one implementation, in step S1:

[0013] The catalyst is either a palladium diimide catalyst or a nickel diimide catalyst;

[0014] The epoxy group-containing monomer is one of glycidyl acrylate, glycidyl methacrylate, 1,2-epoxy-5-hexene, or 1,2-epoxy-7-octene.

[0015] The siloxane monomer is one of vinylpentamethyldisiloxane, vinyltrimethoxysilane, or vinyltriethoxysilane;

[0016] The anhydrous solvent is either dichloromethane or tetrahydrofuran.

[0017] The epoxy groups have good compatibility with the epoxy resin matrix, and the siloxane groups have good compatibility with polydimethylsiloxane. The polydimethylsiloxane flexible material is used to toughen the epoxy resin, so that the conductive interface layer has a certain degree of flexibility. After assembly, it can provide a good seal between the bipolar plate and the copper plate, preventing the copper plate from being oxidized by air after long-term charging and discharging, which would increase the contact resistance.

[0018] In one implementation, in step S1:

[0019] The reaction is carried out at a pressure of 0.1~1MPa, a temperature of 25℃, and a time of 12~24h.

[0020] The post-processing method is as follows: after the reaction is completed, pour out the reaction solution, add concentrated hydrochloric acid and hydrogen peroxide, stir evenly, then add methanol dropwise, centrifuge after the product precipitates, pour out the supernatant, redissolve the product in an anhydrous solvent, add methanol and centrifuge, repeat the dissolution and centrifugation, and dry to obtain the functional hyperbranched polymer.

[0021] In one implementation, in step S2:

[0022] The mass ratio of the functional hyperbranched polymer, carbon nanotubes, polydimethylsiloxane, curing agent A, epoxy resin and curing agent B is (2~8):(7.5~12.5):(10~30):(1~3):(70~90):(40~80).

[0023] Functional hyperbranched polymers have CH-π non-covalent interactions with carbon nanotubes, which can modify carbon nanotubes in situ. At the same time, the ends of the polymers contain siloxane groups and epoxy groups, which further enhances the compatibility between carbon nanotubes, polydimethylsiloxane, and epoxy resin, making the carbon nanotubes more uniformly dispersed in the conductive layer.

[0024] In one implementation, in step S2:

[0025] The curing agent A is a polydimethylsiloxane curing agent, which is a mixture of polydimethyl-methylvinylsiloxane and platinum.

[0026] The curing agent B is a polyamide with a molecular weight of 600-1100.

[0027] Polyamides with a molecular weight of 600-1100 can effectively improve the curing degree of epoxy resin and enhance the performance of integrated current collectors.

[0028] In one implementation, in step S2:

[0029] The ball milling time is 0.5 to 2 hours, and the speed is 500 to 800 rad / min.

[0030] Ball milling not only improves the dispersibility of carbon nanotubes but also increases the compatibility between polydimethylsiloxane and epoxy resin, forming a uniform conductive layer during curing.

[0031] In one implementation, in step S3:

[0032] The coating process is performed using a doctor blade coating process, with a coating speed of 8~10mm / s, and the coating process is repeated 1~3 times.

[0033] The hot pressing temperature is 100~120℃, the pressure is 3~7MPa, and the hot pressing time is 10~60min.

[0034] Epoxy resin, as the conductive interface layer matrix, has strong adhesive properties. During curing, it can firmly bond the bipolar plate and the copper plate, reduce the micro-gap between the bipolar plate and the copper plate, increase the contact area, reduce the contact resistance, and further improve the voltage efficiency and energy efficiency of the vanadium redox flow battery.

[0035] The bipolar plate is one of a carbon-plastic composite bipolar plate or a flexible graphite plate, and the thickness of the bipolar plate is 0.6~1mm;

[0036] The thickness of the flexible conductive interface layer is 0.01~0.05mm.

[0037] Secondly, an integrated current collector assembly is disclosed, which is prepared using the aforementioned method for preparing an integrated current collector assembly.

[0038] Thirdly, an application of an integrated current collector component is disclosed, which is applied to a vanadium redox flow battery.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. This invention uses epoxy resin as the conductive interface layer matrix, which has a strong adhesive effect. During curing, it can firmly bond the bipolar plate and the copper plate, reduce the micro gap between the bipolar plate and the copper plate, increase the contact area, reduce the contact resistance, and further improve the voltage efficiency and energy efficiency of the vanadium redox flow battery.

[0041] 2. This invention introduces polydimethylsiloxane flexible material to toughen epoxy resin, giving the conductive interface layer a certain degree of flexibility. After assembly, it provides a better seal between the bipolar plate and the copper plate, preventing the copper plate from being oxidized by air after long-term charging and discharging, which would increase the contact resistance.

[0042] 3. The present invention synthesizes a functional hyperbranched polymer containing epoxy groups and siloxane groups, which can form CH-π non-covalent bonds with carbon nanotubes to functionalize them. At the same time, the epoxy groups and siloxane groups have good compatibility with epoxy resin and polydimethylsiloxane, respectively. During ball milling and blending, not only can the dispersibility of carbon nanotubes be improved, but the compatibility between polydimethylsiloxane and epoxy resin can also be increased. During curing, a uniform conductive layer is formed. Attached Figure Description

[0043] Figure 1 This is a flowchart of the preparation process of Embodiment 1 of the present invention;

[0044] Figure 2 These are the contact DC resistances of Embodiments 1-4 and Comparative Example 4 of the present invention. Detailed Implementation

[0045] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0046] like Figure 1 As shown, a method for fabricating an integrated current collector module includes the following steps:

[0047] Step S1: Add the catalyst, epoxy-containing monomer, and siloxane monomer to an anhydrous solvent, introduce ethylene, and react at a pressure of 0.1~1 MPa and a temperature of 25℃ for 12~24 h. After the reaction is complete, pour off the reaction solution, add concentrated hydrochloric acid and hydrogen peroxide, stir evenly, and then add methanol dropwise. After the product precipitates, centrifuge, pour off the supernatant, redissolve the product in an anhydrous solvent, add methanol, and centrifuge. Repeat the dissolution and centrifugation process 3 times. After drying, the functional hyperbranched polymer is obtained. The mass ratio of catalyst, epoxy-containing monomer, siloxane monomer, and anhydrous solvent is 0.5:(2~4):(2~4):(20~40). The catalyst is either a palladium diimide catalyst or a nickel diimide catalyst. The epoxy-containing monomer is either glycidyl acrylate, glycidyl methacrylate, 1,2-epoxy-5-hexene, or 1,2-epoxy-7-octene. The siloxane monomer is one of vinylpentamethyldisiloxane, vinyltrimethoxysilane, or vinyltriethoxysilane. The anhydrous solvent is one of dichloromethane or tetrahydrofuran.

[0048] Step S2: The functional hyperbranched polymer, carbon nanotubes, polydimethylsiloxane, curing agent A, epoxy resin, and curing agent B are placed in a ball mill jar and ball-milled at a speed of 500-800 rad / min for 0.5-2 h to obtain a mixture. The mass ratio of the functional hyperbranched polymer, carbon nanotubes, polydimethylsiloxane, curing agent A, epoxy resin, and curing agent B is (2-8):(7.5-12.5):(10-30):(1-3):(70-90):(40-80). Curing agent A is a polydimethylsiloxane curing agent; curing agent B is a polyamide.

[0049] Step S3: Using a doctor blade coating process, the mixture is uniformly coated onto one side of the bipolar plate with a thickness of 0.6-1 mm at a coating speed of 8-10 mm / s. This coating process is repeated 1-3 times. A copper plate is then bonded to the surface coated with the mixture. A flexible conductive interface layer with a thickness of 0.01-0.05 mm is formed by hot pressing at a temperature of 100-120℃ and a pressure of 3-7 MPa for 10-60 minutes. After complete curing, an integrated current collector is obtained. The bipolar plate is either a carbon-plastic composite bipolar plate or a flexible graphite plate.

[0050] Example 1: The following technical solution is adopted.

[0051] Step S1: Add 0.5g palladium diimide catalyst, 2g glycidyl methacrylate, and 3g vinylpentamethyldisiloxane to 30g anhydrous dichloromethane, introduce ethylene, adjust the ethylene pressure to 0.1MPa, and react at 25℃ for 12h. After the reaction is complete, pour out the reaction solution, add concentrated hydrochloric acid and hydrogen peroxide, stir evenly, and then add methanol dropwise. After the product precipitates, centrifuge, pour out the supernatant, redissolve the product in an anhydrous solvent, add methanol, and centrifuge. Repeat the dissolution and centrifugation process 3 times. Place the precipitate in a vacuum drying oven at 40℃ and dry to obtain the functional hyperbranched polymer.

[0052] Step S2: 5g of functional hyperbranched polymer, 10g of carbon nanotubes, 20g of polydimethylsiloxane, 2g of polydimethylsiloxane curing agent, 80g of epoxy resin, and 60g of polyamide are ball-milled at 800 rad / min for 0.5h to obtain a mixture.

[0053] Step S3: Using a scraper coating process, the mixture is uniformly coated onto one side of a 0.8mm thick carbon-plastic composite bipolar plate at a coating speed of 10mm / s. The coating process is repeated 3 times. Then, it is covered onto the copper plate surface and hot-pressed at 100℃ and 5MPa for 20 minutes to form a flexible conductive interface layer, thus obtaining an integrated current collector.

[0054] Example 2: The following technical solution is adopted.

[0055] Step S1: Add 0.5g palladium diimide catalyst, 3g glycidyl acrylate, and 2g vinyltrimethoxysilane to 20g anhydrous dichloromethane, introduce ethylene, adjust the ethylene pressure to 0.1MPa, and react at 25℃ for 24h. After the reaction is complete, pour out the reaction solution, add concentrated hydrochloric acid and hydrogen peroxide, stir evenly, and then add methanol dropwise. After the product precipitates, centrifuge, pour out the supernatant, redissolve the product in an anhydrous solvent, add methanol, and centrifuge. Repeat the dissolution and centrifugation process 3 times. Place the precipitate in a vacuum drying oven at 40℃ and dry to obtain the functional hyperbranched polymer.

[0056] Step S2: 2g of functional hyperbranched polymer, 7.5g of carbon nanotubes, 10g of polydimethylsiloxane, 1g of polydimethylsiloxane curing agent, 90g of epoxy resin, and 80g of polyamide are ball-milled at 600 rad / min for 1 hour to obtain a mixture.

[0057] Step S3: Using a scraper coating process, the mixture is uniformly coated onto one side of a 0.8mm thick carbon-plastic composite bipolar plate at a coating speed of 10mm / s. The coating process is repeated 3 times. Then, it is covered onto the copper plate surface and hot-pressed at 100℃ and 3MPa for 10min to form a flexible conductive interface layer, thus obtaining an integrated current collector.

[0058] Example 3: The following technical solution is adopted.

[0059] Step S1: Add 0.5g palladium diimide catalyst, 3g 1,2-epoxy-5-hexene, and 4g vinyltriethoxysilane to 40g anhydrous dichloromethane, introduce ethylene, adjust the ethylene pressure to 0.5MPa, and react at 25℃ for 24h. After the reaction is complete, pour out the reaction solution, add concentrated hydrochloric acid and hydrogen peroxide, stir evenly, and then add methanol dropwise. After the product precipitates, centrifuge, pour out the supernatant, redissolve the product in an anhydrous solvent, add methanol, and centrifuge. Repeat the dissolution and centrifugation process 3 times. Place the precipitate in a vacuum drying oven at 40℃ and dry to obtain the functional hyperbranched polymer.

[0060] Step S2: 8g of functional hyperbranched polymer, 12.5g of carbon nanotubes, 20g of polydimethylsiloxane, 2g of polydimethylsiloxane curing agent, 80g of epoxy resin, and 60g of polyamide are ball-milled at 500 rad / min for 2 hours to obtain a mixture.

[0061] Step S3: Using a scraper coating process, the mixture is uniformly coated onto one side of a 0.6mm thick carbon-plastic composite bipolar plate at a coating speed of 10mm / s. The coating process is repeated 3 times. Then, it is covered onto the copper plate surface and hot-pressed at 100℃ and 5MPa for 40min to form a flexible conductive interface layer, thus obtaining an integrated current collector.

[0062] Example 4: The following technical solution is adopted.

[0063] Step S1: Add 0.5g palladium diimide catalyst, 4g 1,2-epoxy-7-octene, and 2g vinyltrimethoxysilane to 40g anhydrous tetrahydrofuran, introduce ethylene, adjust the ethylene pressure to 1MPa, and react at 25℃ for 24h. After the reaction is complete, pour out the reaction solution, add concentrated hydrochloric acid and hydrogen peroxide, stir evenly, and then add methanol dropwise. After the product precipitates, centrifuge, pour out the supernatant, redissolve the product in an anhydrous solvent, add methanol, and centrifuge. Repeat the dissolution and centrifugation process 3 times. Place the precipitate in a vacuum drying oven at 40℃ and dry to obtain the functional hyperbranched polymer.

[0064] Step S2: 4g of functional hyperbranched polymer, 10g of carbon nanotubes, 30g of polydimethylsiloxane, 3g of polydimethylsiloxane curing agent, 70g of epoxy resin, and 40g of polyamide are ball-milled at 800 rad / min for 2 hours to obtain a mixture.

[0065] Step S3: Using a scraper coating process, the mixture is uniformly coated onto one side of a 1mm thick carbon-plastic composite bipolar plate at a coating speed of 8mm / s. The coating process is repeated once. Then, it is covered onto the copper plate surface and hot-pressed at 120℃ and 7MPa for 60min to form a flexible conductive interface layer, thus obtaining an integrated current collector.

[0066] Example 5: The following technical solution is adopted.

[0067] Step S1: Add 0.5g nickel diimide catalyst, 2g glycidyl methacrylate, and 3g vinylpentamethyldisiloxane to 30g anhydrous dichloromethane, introduce ethylene, adjust the ethylene pressure to 0.5MPa, and react at 25℃ for 18h. After the reaction is complete, pour out the reaction solution, add concentrated hydrochloric acid and hydrogen peroxide, stir evenly, and then add methanol dropwise. After the product precipitates, centrifuge, pour out the supernatant, redissolve the product in an anhydrous solvent, add methanol, and centrifuge. Repeat the dissolution and centrifugation process 3 times. Place the precipitate in a vacuum drying oven at 40℃ and dry to obtain the functional hyperbranched polymer.

[0068] Step S2: 8g of functional hyperbranched polymer, 10g of carbon nanotubes, 20g of polydimethylsiloxane, 2g of polydimethylsiloxane curing agent, 80g of epoxy resin, and 60g of polyamide are ball-milled at 800 rad / min for 0.5h to obtain a mixture.

[0069] Step S3: Using a doctor blade coating process, the mixture is evenly coated onto one side of a 0.8mm thick flexible graphite plate at a coating speed of 8mm / s. The coating process is repeated twice. Then, it is covered onto the surface of a copper plate and hot-pressed at 110℃ and 7MPa for 20 minutes to form a flexible conductive interface layer, thus obtaining an integrated current collector.

[0070] Example 6: The following technical solution is adopted.

[0071] Step S1: Add 0.5g palladium diimide catalyst, 3g glycidyl acrylate, and 3g vinyltrimethoxysilane to 30g anhydrous dichloromethane, introduce ethylene, adjust the ethylene pressure to 0.1MPa, and react at 25℃ for 24h. After the reaction is complete, pour out the reaction solution, add concentrated hydrochloric acid and hydrogen peroxide, stir evenly, and then add methanol dropwise. After the product precipitates, centrifuge, pour out the supernatant, redissolve the product in an anhydrous solvent, add methanol, and centrifuge. Repeat the dissolution and centrifugation process 3 times. Place the precipitate in a vacuum drying oven at 40℃ and dry to obtain the functional hyperbranched polymer.

[0072] Step S2: 6g of functional hyperbranched polymer, 12.5g of carbon nanotubes, 10g of polydimethylsiloxane, 1g of polydimethylsiloxane curing agent, 90g of epoxy resin, and 80g of polyamide are ball-milled at 500 rad / min for 2 hours to obtain a mixture.

[0073] Step S3: Using a doctor blade coating process, the mixture is evenly coated onto one side of a 0.8mm thick flexible graphite plate at a coating speed of 10mm / s. The coating process is repeated 3 times. Then, it is covered onto the surface of a copper plate and hot-pressed at 100℃ and 3MPa for 10 minutes to form a flexible conductive interface layer, thus obtaining an integrated current collector.

[0074] Comparative Example 1: The following technical solution is adopted.

[0075] The only difference from Example 1 is that no functional hyperbranched polymer was added in step S2.

[0076] Comparative Example 2: The following technical solution is adopted.

[0077] Compared with Example 1, the difference is that in step S2, polydimethylsiloxane and polydimethylsiloxane curing agent were not added. 5g of functional hyperbranched polymer, 10g of carbon nanotubes, 100g of epoxy resin and 80g of polyamide were ball-milled at 800 rad / min for 0.5h to obtain a mixture.

[0078] Comparative Example 3: The following technical solution is adopted.

[0079] Compared with Example 1, the difference is that in step S2, epoxy resin and polyamide were not added. Instead, 5g of functional hyperbranched polymer, 10g of carbon nanotubes, 100g of polydimethylsiloxane, and 10g of polydimethylsiloxane curing agent were ball-milled at 800 rad / min for 0.5h to obtain a mixture.

[0080] Comparative Example 4: The following technical solution is adopted.

[0081] A 0.8mm thick carbon-plastic composite bipolar plate is used in tight contact with a copper plate, but an integrated current collector is not fabricated.

[0082] Comparative Example 5: The following technical solution is adopted.

[0083] A 0.8mm thick flexible graphite plate was pressed tightly against a copper plate, but no integrated current collector was fabricated.

[0084] Battery performance testing: The current collector components obtained in Examples 1-6 and Comparative Examples 1-5 were assembled into battery stacks for battery performance testing. Coulombic efficiency, voltage efficiency, energy efficiency, and voltage efficiency (%) after 200 cycles were recorded under the same test conditions. The test results are shown in Table 1.

[0085] Table 1 Battery Performance Test Table

[0086]

[0087] like Figure 2As shown, Examples 1-4 exhibited lower contact DC resistance compared to Comparative Example 4, indicating that the introduction of a flexible conductive layer can reduce the contact resistance between the bipolar plate and the copper plate. As shown in Table 1, Examples 1-4 showed higher energy efficiency and voltage efficiency compared to Comparative Example 4, and Examples 5-6 showed higher energy efficiency and voltage efficiency compared to Comparative Example 5. This is because the introduction of a flexible conductive layer between the copper plate and the bipolar plate reduced the gap between them, lowering the contact resistance and ohmic loss. Furthermore, the flexible conductive layer increased the sealing at the interface, mitigating oxidation on the copper plate surface, thus improving the energy efficiency and voltage efficiency of the vanadium redox flow battery. Compared to Comparative Example 1, Examples 1-6 all showed higher energy efficiency and voltage efficiency, indicating that the functional hyperbranched polymer can improve the performance of the flexible conductive interface. During ball milling and blending, carbon nanotubes can be modified in situ through CH-π non-covalent bond forces. Simultaneously, the epoxy groups and siloxane groups at the ends of the functional hyperbranched polymer... The polydimethylsiloxane exhibits good compatibility with both epoxy resin and polydimethylsiloxane, improving not only the dispersion of carbon nanotubes but also the compatibility between polydimethylsiloxane and epoxy resin. During curing, a uniform conductive layer is formed, thereby improving the energy efficiency and voltage efficiency of the vanadium redox flow battery. Compared to Comparative Example 2, Examples 1-6 all demonstrate higher voltage efficiency stability, indicating that the introduction of polydimethylsiloxane as a flexible material to toughen the epoxy resin provides a certain degree of flexibility to the conductive interface layer. This results in a better seal between the bipolar plate and the copper plate after assembly, preventing oxidation of the copper plate by air after long-term charging and discharging, which would increase contact resistance and reduce voltage efficiency. Compared to Comparative Example 3, Examples 1-6 all exhibit higher energy efficiency and voltage efficiency. Because epoxy resin, as the conductive interface layer matrix, has strong adhesive properties, it can firmly bond the bipolar plate and copper plate during curing, reducing micro-gaps between them, increasing the contact area, and lowering contact resistance, further improving the voltage efficiency and energy efficiency of the vanadium redox flow battery.

[0088] From the above detailed description of the embodiments of the present invention, it can be understood that the present invention provides an integrated current collector assembly, its preparation method and application. By preparing a flexible conductive interface layer of carbon nanotube / polydimethylsiloxane / epoxy resin to form an integrated current collector assembly, the contact resistance between the bipolar plate and the copper plate is reduced, and the sealing at the interface is increased. This makes the side of the copper plate in contact with the bipolar plate less prone to oxidation by air during long-term charging and discharging, thereby improving the voltage efficiency, energy efficiency and capacity retention of the vanadium redox flow battery.

[0089] Although the present invention has been preferably disclosed above, it is not intended to limit the present invention. Any person skilled in the art may make appropriate modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims.

Claims

1. A method for fabricating an integrated current collector assembly, characterized in that, Includes the following steps: Step S1: The catalyst, epoxy group-containing monomer, and siloxane monomer are added to an anhydrous solvent, ethylene is introduced to carry out the reaction, and then post-processed to obtain a functional hyperbranched polymer; the catalyst is one of palladium diimide catalyst or nickel diimide catalyst; Step S2: The functional hyperbranched polymer, carbon nanotubes, polydimethylsiloxane, curing agent A, epoxy resin, and curing agent B are placed in a ball mill jar and ball-milled to obtain a mixture; the curing agent A is a polydimethylsiloxane curing agent, which is a mixture of polydimethyl-methylvinylsiloxane and platinum; the curing agent B is a polyamide with a molecular weight of 600-1100; Step S3: The mixture is uniformly coated onto one side of the bipolar plate, and a copper plate is attached to the surface coated with the mixture. A flexible conductive interface layer is formed by hot pressing. After complete curing, an integrated current collector is obtained.

2. The preparation method according to claim 1, characterized in that, In step S1: The mass ratio of the catalyst, epoxy group-containing monomer, siloxane monomer and anhydrous solvent is 0.5:(2~4):(2~4):(20~40).

3. The preparation method according to claim 1, characterized in that, In step S1: The epoxy group-containing monomer is one of glycidyl acrylate, glycidyl methacrylate, 1,2-epoxy-5-hexene, or 1,2-epoxy-7-octene. The siloxane monomer is one of vinylpentamethyldisiloxane, vinyltrimethoxysilane, or vinyltriethoxysilane; The anhydrous solvent is either dichloromethane or tetrahydrofuran.

4. The preparation method according to claim 1, characterized in that, In step S1: The reaction is carried out at a pressure of 0.1~1MPa, a temperature of 25℃, and a time of 12~24h. The post-processing method is as follows: after the reaction is completed, pour out the reaction solution, add concentrated hydrochloric acid and hydrogen peroxide, stir evenly, then add methanol dropwise, centrifuge after the product precipitates, pour out the supernatant, redissolve the product in an anhydrous solvent, add methanol and centrifuge, repeat the dissolution and centrifugation, and dry to obtain the functional hyperbranched polymer.

5. The preparation method according to claim 1, characterized in that, In step S2: The mass ratio of the functional hyperbranched polymer, carbon nanotubes, polydimethylsiloxane, curing agent A, epoxy resin and curing agent B is (2~8):(7.5~12.5):(10~30):(1~3):(70~90):(40~80).

6. The preparation method according to claim 1, characterized in that, In step S2: The ball milling time is 0.5 to 2 hours, and the speed is 500 to 800 rad / min.

7. The preparation method according to claim 1, characterized in that, In step S3: The coating process is performed using a doctor blade coating process, with a coating speed of 8~10mm / s, and the coating process is repeated 1~3 times. The hot pressing temperature is 100~120℃, the pressure is 3~7MPa, and the hot pressing time is 10~60min; The bipolar plate is one of a carbon-plastic composite bipolar plate or a flexible graphite plate, and the thickness of the bipolar plate is 0.6~1mm; The thickness of the flexible conductive interface layer is 0.01~0.05mm.

8. An integrated current collector component, characterized in that, The integrated current collector assembly is prepared using the preparation method described in any one of claims 1 to 7.

9. The integrated current collector assembly as described in claim 8, characterized in that, The integrated current collector is used in vanadium redox flow batteries.

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