A functional current collector without a transition weld

Abstract

The present application relates to the technical field of lithium battery, specifically a functional current collector without adapter welding, comprising the following steps: step 1: laser drilling of a base film to form a round hole, obtaining base film A; step 2: filling the round hole of the base film A with medium-temperature curing conductive adhesive and drying to obtain base film B; step 3: surface coating treatment of the base film B; thus obtaining a functional current collector without adapter welding.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, specifically a functional current collector that does not require adapter soldering. Background Technology

[0002] Functional current collectors have garnered widespread attention in the lithium battery industry due to their ability to improve battery energy density and safety. Because their middle layer is a non-conductive polymer layer, they require a bonding process to achieve conductivity. This bonding process involves welding a layer of conventional metal foil to each of the two metal layers. The welded metal foil then draws the current out, and the conductivity is further achieved through pre-welding.

[0003] Because the metal layer must be conductive for it to be used in batteries, and the application of the transition welding process is not yet mature, this has hindered the widespread adoption of functional current collectors to some extent. Furthermore, most existing transition welding equipment is still under development and is expensive. The welding process also requires a large amount of copper / aluminum foil, most of which is discarded in subsequent processes, resulting in material waste.

[0004] In conclusion, obtaining a functional current collector that does not require adapter welding is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a functional current collector that does not require adapter welding, so as to solve the problems mentioned in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A functional current collector that does not require adapter soldering includes the following steps:

[0008] Step 1: Laser-drill holes in the base film to form circular holes, thus obtaining base film A;

[0009] Step 2: Fill the round holes of base film A with medium-temperature curing conductive adhesive, and dry to obtain base film B;

[0010] Step 3: Deposit the surface of base film B to obtain the functional current collector.

[0011] In a further embodiment, the drying temperature is 90–110°C, and the drying time is 20–40 minutes. This is to prevent excessively high baking temperatures from damaging the base film.

[0012] More preferably, the thickness of the base film is 1 to 10 μm; the base film includes one of polyethylene terephthalate (PET) and polypropylene (PP) as the intermediate layer of the functional current collector.

[0013] In a further embodiment, the width of the base film is 250–350 mm.

[0014] In a more optimized manner, step 1 involves the following process: leaving 20-30 mm on each side of the base film, and performing laser drilling at the middle position of the base film with a laser speed of 750-850 mm / s, a laser power of 25-35%, and a frequency of 1400-1600 kHz to form regular circular holes, thereby obtaining base film A.

[0015] In a further embodiment, the circular hole is made by laser drilling, which offers high precision.

[0016] Ideally, the diameter of the circular hole is 0.5–1 mm, and the spacing between the holes is 4–6 mm.

[0017] In a further step, a medium-temperature curing conductive adhesive is applied to the circular hole area to fill the hole, and excess adhesive is scraped off to keep the film surface flat.

[0018] In a more optimized manner, the functional current collector includes one of a composite copper current collector and a composite aluminum current collector; the thickness of the metal layer deposited on both sides of the base film B is 0.5 to 2 μm.

[0019] More optimally, when the functional current collector is a composite aluminum current collector, the coating process is a vapor deposition process; when the functional current collector is a composite copper current collector, the coating process is a magnetron sputtering process or an electroplating process.

[0020] A more optimized method for preparing the medium-temperature curing conductive adhesive is as follows:

[0021] S1-1: Preparation of modified conductive filler: Graphene oxide and carbon nanotubes are ground and mixed and added to deionized water. The mixture is ultrasonically treated for 2-3 hours. Ethylenediamine and ammonia are added. The mass ratio of graphene oxide, carbon nanotubes, ethylenediamine, and ammonia is 0.5-1:0.2-0.5:8-10:2-3. The mixture is reacted at 90-100℃ for 12-14 hours. After filtration and drying, the modified conductive filler is obtained.

[0022] S1-2: Preparation of medium-temperature curing conductive adhesive: Modified conductive filler and polyurethane with amide bonds are added to N-methylpyrrolidone and reacted at 70-90℃ for 2-4 hours to obtain modified polyurethane; the modified polyurethane and epoxy resin are ultrasonically mixed evenly to obtain medium-temperature curing conductive adhesive.

[0023] In a more optimized manner, the mass ratio of modified conductive filler to polyurethane with amide bonds in the raw materials of the modified polyurethane is 3-10:100-120.

[0024] In the raw materials of the medium-temperature curing conductive adhesive, the mass ratio of modified polyurethane to epoxy resin is 1.2-1.5:0.5-0.8.

[0025] A more optimized method for preparing the polyurethane with amide bonds is as follows:

[0026] S1-2: Hexamethylenediamine in a molar ratio of 2:2:2 to 2.2 was added to a 20 wt% to 40 wt% sodium hydroxide aqueous solution, followed by the addition of a xylene solution of 1H-pyrazole-1-acyl chloride. The mixture was ultrasonically stirred at 20 to 30 °C for 30 to 60 min, washed, and dried to obtain product A with amide bonds.

[0027] S2-2: Trifluoromethoxyphenyl isocyanate and ethylene glycol are added to N,N-dimethylacetamide and reacted at 60-70°C for 1-3 hours. Then, product A with amide bonds is added and stirred at 70-90°C until homogeneous. The molar ratio of trifluoromethoxyphenyl isocyanate, ethylene glycol, and product A with amide bonds is 5-6:1:1 to obtain polyurethane with amide bonds.

[0028] In this design, polyurethane is selected as the bonding polymer for the medium-temperature curing conductive adhesive, as it possesses both good bonding properties and high-temperature resistance. The introduction of amide bonds further enhances the medium-temperature curing performance of polyurethane. Graphene oxide and carbon nanotubes are used as conductive fillers and composited with polyurethane to improve interfacial properties and generate synergistic effects, resulting in a medium-temperature curing conductive adhesive with both high bonding performance and high conductivity.

[0029] In order to improve the medium-temperature curing performance of polyurethane, polyurethane is modified and amide bonds are introduced to further improve its performance. In addition, pyrazole groups and fluorine elements are introduced during the modification process to improve electrical conductivity and chemical stability.

[0030] Graphene oxide and carbon nanotubes possess high electrical conductivity; however, their interfacial composite ability with polyurethane presents challenges. To improve the interfacial performance between the conductive filler and polyurethane, the conductive filler is aminated and reacts with the isocyanate groups in the polyurethane, resulting in successful composite formation. Subsequently, epoxy resin is added for further composite formation, introducing epoxy groups to enhance the reaction with active groups in the base film, thereby further improving conductivity and adhesion.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] (1) The solution involves drilling holes in a polymer base film and filling them with medium-temperature curing conductive adhesive, which allows the metal layers on both sides of the functional current collector to conduct through the medium-temperature curing conductive adhesive in the holes. This eliminates the need for the transfer welding process, improves application efficiency, and avoids the waste of a large amount of copper / aluminum foil generated during the transfer welding process.

[0033] (2) The medium-temperature curing conductive adhesive prepared by this method is used in the preparation of functional current collectors. It has good interfacial properties, medium-temperature curing ability and bonding performance. At the same time, it can further improve the conductivity. Attached Figure Description

[0034] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0035] Figure 1 This is a schematic diagram of the base film after laser drilling.

[0036] Figure 2 This is a diagram of a resistance testing method. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] It should be noted that there are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: in the following embodiments, the medium-temperature curing conductive adhesive in Example 1 is of type ALTEXE, purchased from Ao Ke New Material Technology (Shanghai) Co., Ltd.

[0039] Example 1: A functional current collector that does not require adapter soldering, comprising the following steps:

[0040] Step 1: Select a 6μm thick and 300mm wide PET base film as the intermediate layer for the functional current collector. Leave a 25mm gap on each side of the base film. Perform laser drilling in the middle of the base film at a laser speed of 800mm / s, 30% laser power, and a frequency of 1500kHz to form circular holes with a diameter of 0.75mm and a spacing of 5mm between holes. Figure 1 As shown, base film A was obtained;

[0041] Step 2: Fill the circular hole area of ​​the base film A with medium-temperature curing conductive adhesive, so that the medium-temperature curing conductive adhesive fills the circular hole, and scrape off the excess medium-temperature curing conductive adhesive to keep the film surface flat. Then dry at 100℃ for 30 minutes to obtain base film B.

[0042] Step 3: Deposit a 1μm aluminum layer on both sides of the dried base film B using a vapor deposition process to obtain a functional current collector.

[0043] Example 2: A functional current collector that does not require adapter soldering, comprising the following steps:

[0044] Step 1: Preparation of medium-temperature curing conductive adhesive: S1: Hexamethylenediamine in a molar ratio of 2:2:2.1 was added to a 30wt% sodium hydroxide aqueous solution, followed by a xylene solution of 1H-pyrazole-1-acyl chloride. The mixture was ultrasonically stirred at 25°C for 45 min, washed, and dried to obtain product A with amide bonds; S2: Trifluoromethoxyphenyl isocyanate and ethylene glycol were added to N,N-dimethylacetamide and reacted at 65°C for 2 hours. Then, product A with amide bonds was added and stirred evenly at 80°C. The molar ratio of trifluoromethoxyphenyl isocyanate, ethylene glycol, and product A with amide bonds was 5.5:1:1 to obtain product A with amide bonds. S3: Grind and blend graphene oxide and carbon nanotubes, add to deionized water, sonicate for 2.5 hours, add ethylenediamine and ammonia, the mass ratio of graphene oxide, carbon nanotubes, ethylenediamine, and ammonia is 0.8:0.3:9:2.5, react at 95℃ for 13 hours, filter and dry to obtain modified conductive filler; S4: Add modified conductive filler and polyurethane with amide bonds to N-methylpyrrolidone at a mass ratio of 7:110, react at 80℃ for 3 hours to obtain modified polyurethane; Sonicate and mix modified polyurethane and epoxy resin at a mass ratio of 1.3:0.6 to obtain medium-temperature curing conductive adhesive;

[0045] Step 2: Select a 6μm thick and 300mm wide PET base film as the intermediate layer for the functional current collector. Leave 25mm gaps on both sides of the base film. Perform laser drilling in the middle of the base film at a laser speed of 800mm / s, 30% laser power, and a frequency of 1500kHz to form circular holes with a diameter of 0.75mm and a spacing of 5mm between holes. Figure 1 As shown, base film A was obtained;

[0046] Step 3: Fill the circular hole area of ​​the base film A with medium-temperature curing conductive adhesive, so that the medium-temperature curing conductive adhesive fills the circular hole, and scrape off the excess medium-temperature curing conductive adhesive to keep the film surface flat. Then dry at 100℃ for 30 minutes to obtain base film B.

[0047] Step 4: Deposit a 1μm aluminum layer on both sides of the dried base film B using a vapor deposition process to obtain a functional current collector.

[0048] Example 3: A functional current collector that does not require adapter soldering, comprising the following steps:

[0049] Step 1: Preparation of medium-temperature curing conductive adhesive: S1: Hexamethylenediamine in a molar ratio of 1:1:1 was added to a 20wt% sodium hydroxide aqueous solution, followed by a xylene solution of 1H-pyrazole-1-acyl chloride. The mixture was ultrasonically stirred at 25°C for 45 min, washed, and dried to obtain product A with amide bonds; S2: Trifluoromethoxyphenyl isocyanate and ethylene glycol were added to N,N-dimethylacetamide and reacted at 65°C for 2 hours. Then, product A with amide bonds was added and stirred evenly at 80°C. The molar ratio of trifluoromethoxyphenyl isocyanate, ethylene glycol, and product A with amide bonds was 5.5:1:1 to obtain product A with amide bonds. S3: Grind and blend graphene oxide and carbon nanotubes, add to deionized water, sonicate for 2.5 hours, add ethylenediamine and ammonia, the mass ratio of graphene oxide, carbon nanotubes, ethylenediamine, and ammonia is 0.5:0.2:8:2, react at 95℃ for 13 hours, filter and dry to obtain modified conductive filler; S4: Add modified conductive filler and polyurethane with amide bonds to N-methylpyrrolidone at a mass ratio of 3:100, react at 80℃ for 3 hours to obtain modified polyurethane; Sonicate and mix modified polyurethane and epoxy resin at a mass ratio of 1.2:0.5 to obtain medium-temperature curing conductive adhesive;

[0050] Step 2: Select a 6μm thick and 300mm wide PET base film as the intermediate layer for the functional current collector. Leave 25mm gaps on both sides of the base film. Perform laser drilling in the middle of the base film at a laser speed of 800mm / s, 30% laser power, and a frequency of 1500kHz to form circular holes with a diameter of 0.75mm and a spacing of 5mm between holes. Figure 1 As shown, base film A was obtained;

[0051] Step 3: Fill the circular hole area of ​​the base film A with medium-temperature curing conductive adhesive, so that the medium-temperature curing conductive adhesive fills the circular hole, and scrape off the excess medium-temperature curing conductive adhesive to keep the film surface flat. Then dry at 100℃ for 30 minutes to obtain base film B.

[0052] Step 4: Deposit a 1μm aluminum layer on both sides of the dried base film B using a vapor deposition process to obtain a functional current collector.

[0053] Example 4: A functional current collector that does not require adapter soldering, comprising the following steps:

[0054] Step 1: Preparation of medium-temperature curing conductive adhesive: S1: Hexamethylenediamine in a molar ratio of 2:2:2.2 was added to a 40wt% sodium hydroxide aqueous solution, followed by a xylene solution of 1H-pyrazole-1-acyl chloride. The mixture was ultrasonically stirred at 25°C for 45 min, washed, and dried to obtain product A with amide bonds; S2: Trifluoromethoxyphenyl isocyanate and ethylene glycol were added to N,N-dimethylacetamide and reacted at 65°C for 2 hours. Then, product A with amide bonds was added and stirred evenly at 80°C. The molar ratio of trifluoromethoxyphenyl isocyanate, ethylene glycol, and product A with amide bonds was 6:1:1 to obtain product A with amide bonds. S3: Grind and blend graphene oxide and carbon nanotubes, add to deionized water, sonicate for 2.5 hours, add ethylenediamine and ammonia, the mass ratio of graphene oxide, carbon nanotubes, ethylenediamine, and ammonia is 1:0.5:10:3, react at 95℃ for 13 hours, filter and dry to obtain modified conductive filler; S4: Add modified conductive filler and polyurethane with amide bonds to N-methylpyrrolidone at a mass ratio of 10:120, react at 80℃ for 3 hours to obtain modified polyurethane; Sonicate and mix modified polyurethane and epoxy resin at a mass ratio of 1.5:0.8 to obtain medium-temperature curing conductive adhesive;

[0055] Step 2: Select a 6μm thick and 300mm wide PET base film as the intermediate layer for the functional current collector. Leave 25mm gaps on both sides of the base film. Perform laser drilling in the middle of the base film at a laser speed of 800mm / s, 30% laser power, and a frequency of 1500kHz to form circular holes with a diameter of 0.75mm and a spacing of 5mm between holes. Figure 1 As shown, base film A was obtained;

[0056] Step 3: Fill the circular hole area of ​​the base film A with medium-temperature curing conductive adhesive, so that the medium-temperature curing conductive adhesive fills the circular hole, and scrape off the excess medium-temperature curing conductive adhesive to keep the film surface flat. Then dry at 100℃ for 30 minutes to obtain base film B.

[0057] Step 4: Deposit a 1μm aluminum layer on both sides of the dried base film B using a vapor deposition process to obtain a functional current collector.

[0058] Comparative Example 1: The composite aluminum current collector that requires welding in the prior art is as follows:

[0059] Step 1: Clean the aluminum metal layer with sodium hydroxide solution, then place it on the predetermined welding position of the metal layers on both sides of the functional current collector, fix it, and weld it for 0.3s with a current of 2000A and an electrode pressure of 10N to obtain the functional current collector.

[0060] Comparative Example 2: Based on Example 2, only carbon nanotubes were introduced as conductive fillers, while the rest of the process remained unchanged. Specifically:

[0061] Step 1: Preparation of medium-temperature curing conductive adhesive: S1: Hexamethylenediamine in a molar ratio of 2:2:2.1 was added to a 30wt% sodium hydroxide aqueous solution, followed by a xylene solution of 1H-pyrazole-1-acyl chloride. The mixture was ultrasonically stirred at 25℃ for 45 min, washed, and dried to obtain product A with amide bonds; S2: Trifluoromethoxyphenyl isocyanate and ethylene glycol were added to N,N-dimethylacetamide and reacted at 65℃ for 2 hours. Then, product A with amide bonds was added and stirred evenly at 80℃. The molar ratio of trifluoromethoxyphenyl isocyanate, ethylene glycol, and product A with amide bonds was 5.5. S3: Carbon nanotubes were added to deionized water and sonicated for 2.5 hours. Ethylenediamine and ammonia were added in a mass ratio of 1:9:2.5. The mixture was reacted at 95°C for 13 hours, filtered, and dried to obtain a modified conductive filler. S4: The modified conductive filler and polyurethane with amide bonds were added to N-methylpyrrolidone in a mass ratio of 7:110 and reacted at 80°C for 3 hours to obtain a modified polyurethane. The modified polyurethane and epoxy resin were ultrasonically mixed in a mass ratio of 1.3:0.6 to obtain a medium-temperature curing conductive adhesive.

[0062] Step 2: Select a 6μm thick and 300mm wide PET base film as the intermediate layer for the functional current collector. Leave 25mm gaps on both sides of the base film. Perform laser drilling in the middle of the base film at a laser speed of 800mm / s, 30% laser power, and a frequency of 1500kHz to form circular holes with a diameter of 0.75mm and a spacing of 5mm between holes. Figure 1 As shown, base film A was obtained;

[0063] Step 3: Fill the circular hole area of ​​the base film A with medium-temperature curing conductive adhesive, so that the medium-temperature curing conductive adhesive fills the circular hole, and scrape off the excess medium-temperature curing conductive adhesive to keep the film surface flat. Then dry at 100℃ for 30 minutes to obtain base film B.

[0064] Step 4: Deposit a 1μm aluminum layer on both sides of the dried base film B using a vapor deposition process to obtain a functional current collector.

[0065] Comparative Example 3, based on Example 2, involved replacing 9-anthracarboxyl chloride with 1H-pyrazole-1-acyl chloride, while keeping the rest of the process unchanged. Specifically:

[0066] Step 1: Preparation of medium-temperature curing conductive adhesive: S1: Hexamethylenediamine in a molar ratio of 2:2:2.1 was added to a 30wt% sodium hydroxide aqueous solution, followed by a xylene solution of 9-anthracarboxyl chloride. The mixture was ultrasonically stirred at 25°C for 45 min, washed, and dried to obtain product A with amide bonds; S2: Trifluoromethoxyphenyl isocyanate and ethylene glycol were added to N,N-dimethylacetamide and reacted at 65°C for 2 hours. Then, product A with amide bonds was added and stirred evenly at 80°C. The molar ratio of trifluoromethoxyphenyl isocyanate, ethylene glycol, and product A with amide bonds was 5.5:1:1 to obtain a conductive adhesive with amide bonds. Polyurethane; S3: Grind and blend graphene oxide and carbon nanotubes, add to deionized water, sonicate for 2.5 hours, add ethylenediamine and ammonia, the mass ratio of graphene oxide, carbon nanotubes, ethylenediamine, and ammonia is 0.8:0.3:9:2.5, react at 95℃ for 13 hours, filter and dry to obtain modified conductive filler; S4: Add modified conductive filler and polyurethane with amide bonds to N-methylpyrrolidone at a mass ratio of 7:110, react at 80℃ for 3 hours to obtain modified polyurethane; Sonicate and mix modified polyurethane and epoxy resin at a mass ratio of 1.3:0.6 to obtain medium-temperature curing conductive adhesive;

[0067] Step 2: Select a 6μm thick and 300mm wide PET base film as the intermediate layer for the functional current collector. Leave 25mm gaps on both sides of the base film. Perform laser drilling in the middle of the base film at a laser speed of 800mm / s, 30% laser power, and a frequency of 1500kHz to form circular holes with a diameter of 0.75mm and a spacing of 5mm between holes. Figure 1 As shown, base film A was obtained;

[0068] Step 3: Fill the circular hole area of ​​the base film A with medium-temperature curing conductive adhesive, so that the medium-temperature curing conductive adhesive fills the circular hole, and scrape off the excess medium-temperature curing conductive adhesive to keep the film surface flat. Then dry at 100℃ for 30 minutes to obtain base film B.

[0069] Step 4: Deposit a 1μm aluminum layer on both sides of the dried base film B using a vapor deposition process to obtain a functional current collector.

[0070] Comparative Example 4: Based on Example 2, the polyurethane was replaced with polyurethane containing amide bonds, while the rest of the process remained unchanged. Specifically:

[0071] Step 1: Preparation of medium-temperature curing conductive adhesive: S1 Grind and blend graphene oxide and carbon nanotubes, add to deionized water, sonicate for 2.5 hours, add ethylenediamine and ammonia, the mass ratio of graphene oxide, carbon nanotubes, ethylenediamine, and ammonia is 0.8:0.3:9:2.5, react at 95℃ for 13 hours, filter and dry to obtain modified conductive filler; S2: Add modified conductive filler and polyurethane to N-methylpyrrolidone at a mass ratio of 7:110, react at 80℃ for 3 hours to obtain modified polyurethane; Sonicate and mix modified polyurethane and epoxy resin at a mass ratio of 1.3:0.6 to obtain medium-temperature curing conductive adhesive;

[0072] Step 2: Select a 6μm thick and 300mm wide PET base film as the intermediate layer for the functional current collector. Leave 25mm gaps on both sides of the base film. Perform laser drilling in the middle of the base film at a laser speed of 800mm / s, 30% laser power, and a frequency of 1500kHz to form circular holes with a diameter of 0.75mm and a spacing of 5mm between holes. Figure 1 As shown, base film A was obtained;

[0073] Step 3: Fill the circular hole area of ​​the base film A with medium-temperature curing conductive adhesive, so that the medium-temperature curing conductive adhesive fills the circular hole, and scrape off the excess medium-temperature curing conductive adhesive to keep the film surface flat. Then dry at 100℃ for 30 minutes to obtain base film B.

[0074] Step 4: Deposit a 1μm aluminum layer on both sides of the dried base film B using a vapor deposition process to obtain a functional current collector.

[0075] Testing experiment: The performance of the functional current collectors that do not require adapter soldering prepared in Examples 1-4 and Comparative Examples 1-4 was tested: (1) Overcurrent resistance test: The test results of the functional current collectors that do not require adapter soldering prepared in Examples 1-4 and Comparative Examples 1-4 are shown in Table 1. The test method is as follows: Figure 2 As shown; (2) Sheet resistance test: The sheet resistance of the functional current collector that does not require adapter soldering prepared in Examples 1-2 and Comparative Example 1 was tested using a four-probe sheet resistance tester. The test results are shown in Table 2; (3) The functional current collector that does not require adapter soldering prepared in Examples 1-2 and Comparative Example 1 was made into an 18650 cell (NCM+graphite system) and its internal resistance was further tested. The results are shown in Table 3;

[0076]

[0077] Table 1

[0078]

[0079]

[0080] Table 2

[0081]

[0082] Table 3

[0083] Results Analysis: Analysis of the data in Tables 1, 2, and 3 shows that the proposed method, by drilling holes in the polymer base film and filling them with medium-temperature curing conductive adhesive, allows the metal layers on both sides of the functional current collector to conduct through the adhesive within the holes. This eliminates the need for a bonding process, improves application efficiency, and avoids the waste of large amounts of copper / aluminum foil generated during bonding. The medium-temperature curing conductive adhesive prepared using this method exhibits excellent interfacial properties, medium-temperature curing ability, and adhesion properties when applied to the preparation of functional current collectors. Furthermore, it can further enhance conductivity.

[0084] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A functional current collector that does not require adapter welding, characterized in that: Includes the following steps: Step 1: Laser-drill holes in the base film to form circular holes, thus obtaining base film A; Step 2: Fill the round holes of base film A with medium-temperature curing conductive adhesive, and dry to obtain base film B; Step 3: Deposit the surface of base film B to obtain the functional current collector; The preparation method of the medium-temperature curing conductive adhesive is as follows: S1-1: Preparation of modified conductive filler: Graphene oxide and carbon nanotubes are ground and mixed and added to deionized water. The mixture is ultrasonically treated for 2-3 hours. Ethylenediamine and ammonia are added. The mass ratio of graphene oxide, carbon nanotubes, ethylenediamine, and ammonia is 0.5-1:0.2-0.5:8-10:2-3. The mixture is reacted at 90-100℃ for 12-14 hours. After filtration and drying, the modified conductive filler is obtained. S1-2: Preparation of medium-temperature curing conductive adhesive: Modified conductive filler and polyurethane with amide bonds are added to N-methylpyrrolidone and reacted at 70~90℃ for 2~4 hours to obtain modified polyurethane; the modified polyurethane and epoxy resin are ultrasonically mixed evenly to obtain medium-temperature curing conductive adhesive. The method for preparing the polyurethane with amide bonds is as follows: S1-2: Hexamethylenediamine in a molar ratio of 2:2:2~2.2 was added to a 20wt%~40wt% sodium hydroxide aqueous solution, followed by the addition of a xylene solution of 1H-pyrazole-1-acyl chloride to obtain product A with an amide bond; S2-2: Trifluoromethoxyphenyl isocyanate and ethylene glycol are added to N,N-dimethylacetamide and reacted at 60~70℃ for 1~3 hours. Then, product A with amide bonds is added and stirred evenly at 70~90℃. The molar ratio of trifluoromethoxyphenyl isocyanate, ethylene glycol and product A with amide bonds is 5~6:1:1 to obtain polyurethane with amide bonds.

2. The functional current collector that does not require adapter welding according to claim 1, characterized in that: The thickness of the base film is 1~10µm; the base film includes one of polyethylene terephthalate and polypropylene.

3. The functional current collector that does not require adapter welding according to claim 1, characterized in that: In step 1, the process is as follows: leave 20~30mm on each side of the base film, and perform laser drilling in the middle of the base film at a laser speed of 750~850mm / s and a frequency of 1400~1600kHz to form regular circular holes, thus obtaining base film A.

4. The functional current collector that does not require adapter welding according to claim 3, characterized in that: The diameter of the circular hole is 0.5~1mm, and the spacing between the holes is 4~6mm.

5. A functional current collector that does not require adapter welding according to claim 1, characterized in that: The functional current collector includes one of a composite copper current collector and a composite aluminum current collector; the thickness of the metal layer deposited on both sides of the base film B is 0.5~2µm.

6. A functional current collector that does not require adapter welding according to claim 5, characterized in that: When the functional current collector is a composite aluminum current collector, the coating process is a vapor deposition process; when the functional current collector is a composite copper current collector, the coating process is a magnetron sputtering process or an electroplating process.

7. A functional current collector that does not require adapter welding according to claim 1, characterized in that: In the raw materials of the modified polyurethane, the mass ratio of modified conductive filler and polyurethane with amide bonds is 3~10:100~120. In the raw materials of the medium-temperature curing conductive adhesive, the mass ratio of modified polyurethane to epoxy resin is 1.2~1.5:0.5~0.8.

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