High-binder current collector and preparation method thereof

Abstract

The invention relates to the technical field of functional current collector materials, and particularly discloses a high-binder current collector and a preparation method thereof, in the current collector, one part of the structure is a metal foil-organic layer-metal layer structure, and the other part of the structure is a metal foil-metal layer structure. In the metal foil-metal layer part, the metal layer is directly contacted with the metal foil below the metal layer to form a vertical conductive channel, so that the overall conductive efficiency of the current collector and the charge-discharge function of the battery are greatly improved; in the metal foil-organic layer-metal layer part, the organic layer is fixed between the metal foil and the metal layer through the binder, the stress generated in the cycle process of the battery is absorbed and dissipated through the intrinsic elasticity and toughness of the organic layer, and the anti-stripping performance between the metal and the organic layer is enhanced through the binder with high cohesiveness.

Description

Technical Field

[0001] This invention relates to the field of functional current collector technology, specifically to a high-binder current collector and its preparation method. Background Technology

[0002] Current collectors are fundamental components in electrochemical energy storage devices such as lithium-ion batteries and capacitors, carrying the positive and negative electrode active materials and stably and efficiently transmitting current. They are related to the charge-discharge efficiency, cycle life, and energy density of electrochemical energy storage devices. As electrochemical energy storage technology rapidly develops towards higher energy density, higher power density, and longer cycle life, the shortcomings of traditional functional current collectors are becoming increasingly apparent. In traditional functional current collectors, the bonding between the metal and organic layers is weak. Furthermore, the significant volume change of the current collector during battery charging and discharging generates stress that leads to cracking. The introduction of the organic layer also causes a decrease in the conductivity of the current collector. Therefore, improving the adhesion between the metal and organic layers within the current collector and enhancing its conductivity are crucial for promoting the development of functional current collectors. Summary of the Invention

[0003] The purpose of this invention is to provide a high-adhesion current collector and its preparation method, thereby solving the problems of insufficient adhesion between the current collector metal and the organic layer and poor conductivity of the current collector.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for preparing a high-adhesion current collector, specifically comprising: Step 1: Mix PI-PU block copolymer, KH-560 modified nanocomposite filler, KH-560 modified conductive agent and cyclic polycarbonate to form a metal-organic binder; Step 2: Base film cleaning and plasma treatment to obtain pretreated base film; Step 3: Apply metal-organic adhesive to the surface of the pretreated base film, dry it, and then hot-press it with the metal foil to form a metal foil-organic layer structure; Step 3: A metal layer is formed by magnetron sputtering on the surface of the organic layer in the metal foil-organic layer structure to obtain a current collector with high binder.

[0005] As a limitation of the present invention, the preparation method of the PI-PU block copolymer is as follows: Polyamic acid was added to N,N-dimethylformamide and stirred at 200-300 rpm for 20-30 min to obtain a polyamic acid solution. Polytetrahydrofuran ether diol was added to N,N-dimethylformamide and stirred at 200-300 rpm for 20-30 min. Under nitrogen protection and in an oil bath at 80-90℃, isoflurane diisocyanate and dibutyltin dilaurate catalyst were added and reacted at 80-90℃ for 1-2 h. After the reaction was completed, 1,4-butanediol and the polyamic acid solution were added and the reaction was continued for 1-2 h. After the reaction was completed, the mixture was cooled to obtain a PAA-PU block copolymer solution. The PAA-PU block copolymer solution was spin-coated into a film and then heated to cure. After curing, the mixture was cooled to obtain a PI-PU block copolymer.

[0006] As a limitation of the present invention, the PI-PU block copolymer comprises, by weight, 15-25 parts polyamic acid, 50-70 parts polytetrahydrofuran ether diol, 20-30 parts isoflurane diisocyanate, 0.2-0.4 parts dibutyltin dilaurate catalyst, and 4-10 parts 1,4-butanediol; the heating conditions for curing reaction are 120-130℃ for 1-1.5h, 150-160℃ for 1-1.5h, and 170-180℃ for 1-1.5h.

[0007] As a limitation of this invention, the preparation method of the KH-560 modified nanocomposite filler is as follows: Nano-alumina and nano-silica were added to a mixed solution of anhydrous ethanol and deionized water and ultrasonically dispersed for 10-15 min. Silane coupling agent KH-560 was added, and the pH was adjusted to 4-5. The mixture was stirred at 60-70℃ and 300-400 rpm for 6-8 h. After the reaction was completed, the mixture was filtered and vacuum dried at 70-80℃ for 6-8 h to obtain KH-560 modified nanocomposite filler. The mass ratio of nano-alumina, nano-silica, and silane coupling agent KH-560 is (20-30):(20-30):(6-8).

[0008] As a limitation of this invention, the preparation method of the KH-560 modified conductive agent is as follows: Conductive carbon black and carboxylated carbon nanotubes were mixed and ball-milled for 20-30 min to obtain a composite conductive filler. The composite conductive filler was added to a mixed solution of anhydrous ethanol and deionized water and ultrasonically dispersed for 10-15 min. Silane coupling agent KH-560 was added, and the pH was adjusted to 8-9. The mixture was stirred at 60-70℃ and 300-400 rpm for 6-8 h. After the reaction was completed, the mixture was filtered and vacuum dried at 70-80℃ for 6-8 h to obtain KH-560 modified conductive agent. The mass ratio of conductive carbon black, carboxylated carbon nanotubes, and silane coupling agent KH-560 is (7-9):(1-3):(0.5-0.7).

[0009] As a limitation of the present invention, the metal-organic binder comprises, by weight, 80-90 parts of PI-PU block copolymer, 10-15 parts of KH-560 modified nanocomposite filler, 6-10 parts of KH-560 modified conductive agent, and 4-8 parts of cyclic polycarbonate.

[0010] As a limitation of the present invention, the method for preparing the pretreated base film is as follows: The base film was sequentially immersed in anhydrous ethanol and deionized water, and ultrasonically cleaned for 5-10 minutes each. After cleaning, it was removed and vacuum dried at 70-80℃ for 30-40 minutes. It was then transferred to a plasma treatment device and evacuated to a vacuum of 1×10⁻⁶. -3 Pa-5×10 -3 Pa, argon gas is introduced for plasma cleaning, with the argon gas flow rate set to 40-50 sccm, the power supply to 100-120W, and the cleaning time to 3-5 min. After cleaning, oxygen is introduced for plasma activation, with the argon gas flow rate set to 30-40 sccm, the oxygen flow rate to 10-20 sccm, the power supply to 80-100W, and the activation time to 2-4 min, to obtain the pretreated base film.

[0011] As a limitation of the present invention, the method for preparing the high-adhesion current collector is as follows: Using a dispensing machine, apply metal-organic adhesive to the pretreated base film and dry at 80-100℃ for 5-10 minutes. Then, hot press it with a metal foil, setting the hot pressing temperature to 120-130℃, the hot pressing pressure to 0.3-0.5MPa, and the hot pressing time to 3-5 minutes to form a metal foil-organic layer structure. A metal layer is deposited by magnetron sputtering on the organic layer side of the metal foil-organic layer structure. The metal foil-organic layer structure is then transferred to the magnetron sputtering deposition equipment, and the vacuum is evacuated to 1×10⁻⁶. -3 Pa-5×10 -3 Pa, the substrate is preheated to 80-90℃, argon gas is introduced, the copper target power supply is started, the argon gas flow rate is set to 30sccm, the copper target power supply is 200W, and the deposition time is 120min, and a metal layer is deposited to obtain a high-binder current collector.

[0012] As a limitation of the present invention, after the dispensing coating, the drying temperature is 80-100℃ and the time is 5-10min; the hot pressing composite process conditions include: hot pressing temperature of 120-130℃, hot pressing pressure of 0.3-0.5MPa, and hot pressing time of 3-5min; the magnetron sputtering process conditions include: argon flow rate of 20-30sccm, copper target power supply of 180-200W, deposition time of 60-80min, and the thickness of the formed metal layer is 3-4μm.

[0013] A high-adhesion current collector comprising a metal foil, a metal layer, and an organic layer located between the metal foil and the metal layer, wherein the area of ​​the organic layer is smaller than that of the metal foil, and a portion of the metal layer that does not overlap with the organic layer is deposited on the upper surface of the metal foil.

[0014] The organic layer comprises a base film and an adhesive layer formed by an adhesive.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention uses a PU-PI block copolymer as the resin matrix of the adhesive. The terminal hydroxyl groups of polytetrahydrofuran ether diol react with the isocyanate groups of isophorone diisocyanate to form a polyurethane prepolymer. The terminal isocyanate groups of the prepolymer then react with the terminal amino groups of polyamic acid to form a block copolymer of polyurethane and polyamic acid. Finally, through heat treatment, the polyamic acid segments undergo an imidization reaction and are converted into polyimide segments to form a polyurethane-polyimide block copolymer. This allows the adhesive to simultaneously possess the high elasticity and adhesion of PU segments and the heat resistance, mechanical strength and chemical stability of PI segments, thereby enhancing the peel resistance and chemical stability of the current collector.

[0016] This invention incorporates nano-alumina and nano-silica as reinforcing particles in the binder. The uniformly dispersed nano-alumina and nano-silica significantly improve the modulus, hardness, and puncture resistance of the binder. At the same time, their excellent chemical inertness, together with polycarbonate, forms a physical barrier against electrolyte corrosion. The added conductive carbon black and carboxylated carbon nanotubes act as conductive agents, forming a three-dimensional interconnected conductive network, which significantly reduces the volume resistivity of the binder and enhances the electron transport capability within the current collector.

[0017] In the current collector of this invention, one part has a metal foil-organic layer-metal layer structure, and the other part has a metal foil-metal layer structure. In the metal foil-metal layer part, the metal layer is in direct contact with the metal foil below, forming a vertical conductive channel. Electrons can be transported longitudinally in the conductive channel with extremely low resistance, which greatly improves the overall conductivity of the current collector and the charging and discharging function of the battery. In the metal foil-organic layer-metal layer part, the organic layer is fixed between the metal foil and the metal layer by an adhesive. Through its intrinsic elasticity and toughness, it absorbs and dissipates the stress generated during battery cycling. The highly adhesive adhesive enhances the anti-peeling performance between the metal and the organic layer. The organic layer can also prevent the electrolyte from directly corroding the metal foil below, thus achieving the cycle stability of the battery. Attached Figure Description

[0018] Figure 1 This is a structural diagram of the high-adhesion current collector prepared in Example 1; Figure 2 The structural diagram of the high-binder current collector prepared for Comparative Example 3. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The terminology used in the embodiments is for describing specific implementation schemes, not for limiting the scope of protection of the present invention. The dosages in the embodiments are laboratory-scale tests and can be scaled up proportionally. 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.

[0020] Metal foil (copper foil, thickness: 6μm), base film (PI film, thickness: 8μm), nano-alumina (particle size: 30nm), nano-silica (particle size: 20nm), conductive carbon black (particle size: 1μm), carboxylated carbon nanotubes (diameter: 15nm, length: 3μm, carboxyl content: 3.0wt%), PAA (Mn=3000), PTMG (Mn=1000), cyclic polycarbonate (Mn=2000).

[0021] The preparation method of KH-560 modified nanocomposite filler is as follows: 20g of nano-alumina and 20g of nano-silica were added to a mixed solution of 200mL of anhydrous ethanol and 20mL of deionized water and ultrasonically dispersed for 10min. Then, 8g of silane coupling agent KH-560 was added, the pH was adjusted to 5, and the mixture was stirred at 60℃ and 400rpm for 6h. After the reaction was completed, the mixture was filtered and vacuum dried at 80℃ for 6h to obtain KH-560 modified nanocomposite filler.

[0022] The preparation method of KH-560 modified conductive agent is as follows: 9g of conductive carbon black and 1g of carboxylated carbon nanotubes were mixed and ball-milled for 30 min to obtain a composite conductive filler. 10g of the composite conductive filler was added to a mixed solution of 100mL anhydrous ethanol and 10mL deionized water and ultrasonically dispersed for 10 min. 0.5g of silane coupling agent KH-560 was added, and the pH was adjusted to 8. The mixture was stirred at 60℃ and 400rpm for 6 h. After the reaction was completed, the mixture was filtered and vacuum dried at 80℃ for h to obtain KH-560 modified conductive agent.

[0023] Example 1: A method for preparing a high-adhesion current collector, specifically as follows: Step 1: Add 15g PAA to 100mL N,N-dimethylformamide and stir at 200rpm for 20min to obtain PAA solution. Add 50g PTMG to 200mL N,N-dimethylformamide and stir at 200rpm for 20min. Under nitrogen protection and an 80℃ oil bath, add 20g IPDI and 0.2g dibutyltin dilaurate catalyst and react at 80℃ for 1.5h. After the reaction is complete, add 4g 1,4-butanediol and PAA solution and continue the reaction for 1.5h. After the reaction is complete, cool to obtain PAA-PU block copolymer solution. Spin-coat the PAA-PU block copolymer solution into a film and then heat to cure. Set the heating conditions as follows: heat at 120℃ for 1h, heat at 150℃ for 1h, and heat at 180℃ for 1h. After curing, cool to obtain PI-PU block copolymer. Step 2: Add 80g of PI-PU block copolymer to 500mL of N,N-dimethylformamide, stir at 200rpm for 20min, add 10g of KH-560 modified nanocomposite filler, 6g of KH-560 modified conductive agent and 4g of cyclic polycarbonate, disperse at 1000rpm for 15min to obtain metal-organic binder; Step 3: Immerse the base film sequentially in anhydrous ethanol and deionized water, and ultrasonically clean each for 5 minutes. After cleaning, remove the film and vacuum dry it at 80°C for 30 minutes. Then transfer it to a plasma treatment device and evacuate it to a vacuum of 5 × 10⁻⁶. -3 Pa, argon gas was introduced for plasma cleaning, with the argon gas flow rate set to 50 sccm, the power supply to 120 W, and the cleaning time to 5 min. After cleaning, oxygen was introduced for plasma activation, with the argon gas flow rate set to 40 sccm, the oxygen flow rate to 20 sccm, the power supply to 80 W, and the activation time to 3 min, to obtain the pretreated base film. Step 4: Using a dispensing machine, apply metal-organic adhesive to the pretreated base film, dry at 100°C for 5 minutes, and then hot-press it with a metal foil. Set the hot-pressing temperature to 120°C, the hot-pressing pressure to 0.5 MPa, and the hot-pressing time to 5 minutes to form a metal foil-organic layer structure. Step 5: Deposit a metal layer by magnetron sputtering on the organic layer side of the metal foil-organic layer structure, transfer the metal foil-organic layer structure to the magnetron sputtering deposition equipment, and evacuate to 5×10⁻⁶. -3 Pa, the substrate is preheated to 80℃, argon gas is introduced, the copper target power supply is started, the argon gas flow rate is set to 30sccm, the copper target power supply is 200W, the deposition time is 60min, a metal layer is deposited and formed with a metal layer thickness of 3μm, and a high binder current collector is obtained.

[0024] Example 2: A method for preparing a high-adhesion current collector, specifically as follows: Step 1: Add 20g PAA to 100mL N,N-dimethylformamide and stir at 200rpm for 20min to obtain PAA solution. Add 60g PTMG to 200mL N,N-dimethylformamide and stir at 200rpm for 20min. Under nitrogen protection and an 80℃ oil bath, add 25g IPDI and 0.2g dibutyltin dilaurate catalyst and react at 80℃ for 1.5h. After the reaction is complete, add 6g 1,4-butanediol and PAA solution and continue the reaction for 1.5h. After the reaction is complete, cool to obtain PAA-PU block copolymer solution. Spin-coat the PAA-PU block copolymer solution into a film and then heat to cure. Set the heating conditions as follows: heat at 120℃ for 1h, heat at 150℃ for 1h, and heat at 180℃ for 1h. After curing, cool to obtain PI-PU block copolymer. Step 2: Add 85g of PI-PU block copolymer to 500mL of N,N-dimethylformamide, stir at 200rpm for 20min, add 12g of KH-560 modified nanocomposite filler, 8g of KH-560 modified conductive agent and 6g of cyclic polycarbonate, disperse at 1000rpm for 15min to obtain metal-organic binder; Step 3: Immerse the base film sequentially in anhydrous ethanol and deionized water, and ultrasonically clean each for 5 minutes. After cleaning, remove the film and vacuum dry it at 80°C for 30 minutes. Then transfer it to a plasma treatment device and evacuate it to a vacuum of 5 × 10⁻⁶. -3 Pa, argon gas was introduced for plasma cleaning, with the argon gas flow rate set to 50 sccm, the power supply to 120 W, and the cleaning time to 5 min. After cleaning, oxygen was introduced for plasma activation, with the argon gas flow rate set to 40 sccm, the oxygen flow rate to 20 sccm, the power supply to 80 W, and the activation time to 3 min, to obtain the pretreated base film. Step 4: Using a dispensing machine, apply metal-organic adhesive to the pretreated base film, dry at 100°C for 5 minutes, and then hot-press it with a metal foil. Set the hot-pressing temperature to 120°C, the hot-pressing pressure to 0.5 MPa, and the hot-pressing time to 5 minutes to form a metal foil-organic layer structure. Step 5: Deposit a metal layer by magnetron sputtering on the organic layer side of the metal foil-organic layer structure, transfer the metal foil-organic layer structure to the magnetron sputtering deposition equipment, and evacuate to 5×10⁻⁶. -3 Pa, the substrate is preheated to 80℃, argon gas is introduced, the copper target power supply is started, the argon gas flow rate is set to 30sccm, the copper target power supply is 200W, the deposition time is 70min, a metal layer is deposited and formed with a metal layer thickness of 3.5μm, and a high binder current collector is obtained.

[0025] Example 3: A method for preparing a high-adhesion current collector, specifically as follows: Step 1: Add 25g PAA to 100mL N,N-dimethylformamide and stir at 200rpm for 20min to obtain PAA solution. Add 70g PTMG to 200mL N,N-dimethylformamide and stir at 200rpm for 20min. Under nitrogen protection and an 80℃ oil bath, add 30g IPDI and 0.2g dibutyltin dilaurate catalyst and react at 80℃ for 1.5h. After the reaction is complete, add 8g 1,4-butanediol and PAA solution and continue the reaction for 1.5h. After the reaction is complete, cool to obtain PAA-PU block copolymer solution. Spin-coat the PAA-PU block copolymer solution into a film and then heat to cure. Set the heating conditions as follows: heat at 120℃ for 1h, heat at 150℃ for 1h, and heat at 180℃ for 1h. After curing, cool to obtain PI-PU block copolymer. Step 2: Add 90g of PI-PU block copolymer to 500mL of N,N-dimethylformamide, stir at 200rpm for 20min, add 14g of KH-560 modified nanocomposite filler, 10g of KH-560 modified conductive agent and 8g of cyclic polycarbonate, disperse at 1000rpm for 15min to obtain metal-organic binder; Step 3: Immerse the base film sequentially in anhydrous ethanol and deionized water, and ultrasonically clean each for 5 minutes. After cleaning, remove the film and vacuum dry it at 80°C for 30 minutes. Then transfer it to a plasma treatment device and evacuate it to a vacuum of 5 × 10⁻⁶. -3 Pa, argon gas was introduced for plasma cleaning, with the argon gas flow rate set to 50 sccm, the power supply to 120 W, and the cleaning time to 5 min. After cleaning, oxygen was introduced for plasma activation, with the argon gas flow rate set to 40 sccm, the oxygen flow rate to 20 sccm, the power supply to 80 W, and the activation time to 3 min, to obtain the pretreated base film. Step 4: Using a dispensing machine, apply metal-organic adhesive to the pretreated base film, dry at 100°C for 5 minutes, and then hot-press it with a metal foil. Set the hot-pressing temperature to 120°C, the hot-pressing pressure to 0.5 MPa, and the hot-pressing time to 5 minutes to form a metal foil-organic layer structure. Step 5: Deposit a metal layer by magnetron sputtering on the organic layer side of the metal foil-organic layer structure, transfer the metal foil-organic layer structure to the magnetron sputtering deposition equipment, and evacuate to 5×10⁻⁶. -3 Pa, the substrate is preheated to 80℃, argon gas is introduced, the copper target power supply is started, the argon gas flow rate is set to 30sccm, the copper target power supply is 200W, the deposition time is 80min, a metal layer is deposited and formed with a metal layer thickness of 4μm, and a high binder current collector is obtained.

[0026] Based on Example 1, the following comparative experiments were conducted, specifically Comparative Example 1, Comparative Example 2, and Comparative Example 3, as described below: Comparative Example 1: This comparative example relates to a method for preparing a high-adhesion current collector, which differs from Example 1 in that PI resin and PU resin are directly used in the metal-organic adhesive, specifically: Step 1: Add 40g of PI resin and 40g of PU resin to 500mL of N,N-dimethylformamide, stir at 200rpm for 20min, add 10g of KH-560 modified nanocomposite filler, 6g of KH-560 modified conductive agent and 4g of cyclic polycarbonate, disperse at 1000rpm for 15min to obtain metal-organic binder; Step 2: Immerse the base film sequentially in anhydrous ethanol and deionized water, and ultrasonically clean each for 5 minutes. After cleaning, remove the film and vacuum dry it at 80°C for 30 minutes. Then transfer it to a plasma treatment device and evacuate it to a vacuum of 5 × 10⁻⁶. -3 Pa, argon gas was introduced for plasma cleaning, with the argon gas flow rate set to 50 sccm, the power supply to 120 W, and the cleaning time to 5 min. After cleaning, oxygen was introduced for plasma activation, with the argon gas flow rate set to 40 sccm, the oxygen flow rate to 20 sccm, the power supply to 80 W, and the activation time to 3 min, to obtain the pretreated base film. Step 3: Using a dispensing machine, apply metal-organic adhesive to the pretreated base film, dry at 100°C for 5 minutes, and then hot-press it with a metal foil. Set the hot-pressing temperature to 120°C, the hot-pressing pressure to 0.5 MPa, and the hot-pressing time to 5 minutes to form a metal foil-organic layer structure. Step 4: Deposit a metal layer by magnetron sputtering on the organic layer side of the metal foil-organic layer structure, transfer the metal foil-organic layer structure to the magnetron sputtering deposition equipment, and evacuate to 5×10⁻⁶. -3Pa, the substrate is preheated to 80℃, argon gas is introduced, the copper target power supply is started, the argon gas flow rate is set to 30sccm, the copper target power supply is 200W, the deposition time is 60min, a metal layer is deposited and formed with a metal layer thickness of 3μm, and a high binder current collector is obtained.

[0027] Comparative Example 2: This comparative example relates to a method for preparing a high-adhesion current collector, which differs from Example 1 in that PI resin is directly used in the metal-organic adhesive, specifically: Step 1: Add 80g of PI resin to 500mL of N,N-dimethylformamide, stir at 200rpm for 20min, add 10g of KH-560 modified nanocomposite filler, 6g of KH-560 modified conductive agent and 4g of cyclic polycarbonate, disperse at 1000rpm for 15min to obtain metal-organic binder; Step 2: Immerse the base film sequentially in anhydrous ethanol and deionized water, and ultrasonically clean each for 5 minutes. After cleaning, remove the film and vacuum dry it at 80°C for 30 minutes. Then transfer it to a plasma treatment device and evacuate it to a vacuum of 5 × 10⁻⁶. -3 Pa, argon gas was introduced for plasma cleaning, with the argon gas flow rate set to 50 sccm, the power supply to 120 W, and the cleaning time to 5 min. After cleaning, oxygen was introduced for plasma activation, with the argon gas flow rate set to 40 sccm, the oxygen flow rate to 20 sccm, the power supply to 80 W, and the activation time to 3 min, to obtain the pretreated base film. Step 3: Using a dispensing machine, apply metal-organic adhesive to the pretreated base film, dry at 100°C for 5 minutes, and then hot-press it with a metal foil. Set the hot-pressing temperature to 120°C, the hot-pressing pressure to 0.5 MPa, and the hot-pressing time to 5 minutes to form a metal foil-organic layer structure. Step 4: Deposit a metal layer by magnetron sputtering on the organic layer side of the metal foil-organic layer structure, transfer the metal foil-organic layer structure to the magnetron sputtering deposition equipment, and evacuate to 5×10⁻⁶. -3 Pa, the substrate is preheated to 80℃, argon gas is introduced, the copper target power supply is started, the argon gas flow rate is set to 30sccm, the copper target power supply is 200W, the deposition time is 60min, a metal layer is deposited and formed with a metal layer thickness of 3μm, and a high binder current collector is obtained.

[0028] Comparative Example 3: This comparative example relates to a method for preparing a high-adhesion current collector. The difference from Example 1 is that the current collector does not include a structure in which the metal layer is directly deposited on the metal foil. The other conditions are the same as in Example 1.

[0029] Testing experiment: High-adhesion current collectors were prepared according to each embodiment and comparative example, and their peel strength and volume resistivity were tested.

[0030]

[0031] Conclusion: The test data shows that the high-adhesion current collector prepared in the examples has a higher peel strength than Comparative Examples 1 and 2, and a lower volume resistivity than Comparative Examples 1 and 2. Compared with Example 1, in Comparative Example 3, excluding the portion where the metal layer is directly deposited on the metal foil, the peel strength is increased, while the volume resistivity is significantly increased, and its conductivity is not as good as that of Example 1. The high-adhesion current collector provided by the present invention has good peel resistance and conductivity.

[0032] 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 the spirit or essential characteristics of the invention. 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, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a high-adhesion current collector, characterized in that: Specifically: Step 1: Mix PI-PU block copolymer, KH-560 modified nanocomposite filler, KH-560 modified conductive agent and cyclic polycarbonate to form a metal-organic binder; Step 2: Base film cleaning and plasma treatment to obtain pretreated base film; Step 3: Apply metal-organic adhesive to the surface of the pretreated base film, dry it, and then hot-press it with the metal foil to form a metal foil-organic layer structure; Step 3: A metal layer is formed by magnetron sputtering on the surface of the organic layer in the metal foil-organic layer structure to obtain a current collector with high binder.

2. The method for preparing a high-adhesion current collector according to claim 1, characterized in that: The preparation method of PI-PU block copolymer is as follows: Polyamic acid was added to N,N-dimethylformamide and stirred at 200-300 rpm for 20-30 min to obtain a polyamic acid solution. Polytetrahydrofuran ether diol was added to N,N-dimethylformamide and stirred at 200-300 rpm for 20-30 min. Under nitrogen protection and in an oil bath at 80-90℃, isoflurane diisocyanate and dibutyltin dilaurate catalyst were added and reacted at 80-90℃ for 1-2 h. After the reaction was completed, 1,4-butanediol and the polyamic acid solution were added and the reaction was continued for 1-2 h. After the reaction was completed, the mixture was cooled to obtain a PAA-PU block copolymer solution. The PAA-PU block copolymer solution was spin-coated into a film and then heated to cure. After curing, the mixture was cooled to obtain a PI-PU block copolymer.

3. The method for preparing a high-adhesion current collector according to claim 2, characterized in that: By weight, the PI-PU block copolymer comprises 15-25 parts polyamic acid, 50-70 parts polytetrahydrofuran ether glycol, 20-30 parts isoflurane diisocyanate, 0.2-0.4 parts dibutyltin dilaurate catalyst, and 4-10 parts 1,4-butanediol; the heating conditions for curing reaction are 120-130℃ for 1-1.5h, 150-160℃ for 1-1.5h, and 170-180℃ for 1-1.5h.

4. The method for preparing a high-adhesion current collector according to claim 1, characterized in that: The preparation method of KH-560 modified nanocomposite filler is as follows: Nano-alumina and nano-silica were added to a mixed solution of anhydrous ethanol and deionized water and ultrasonically dispersed for 10-15 min. Silane coupling agent KH-560 was added, and the pH was adjusted to 4-5. The mixture was stirred at 60-70℃ and 300-400 rpm for 6-8 h. After the reaction was completed, the mixture was filtered and vacuum dried at 70-80℃ for 6-8 h to obtain KH-560 modified nanocomposite filler. The mass ratio of nano-alumina, nano-silica, and silane coupling agent KH-560 is (20-30):(20-30):(6-8).

5. The method for preparing a high-adhesion current collector according to claim 1, characterized in that: The preparation method of KH-560 modified conductive agent is as follows: Conductive carbon black and carboxylated carbon nanotubes were mixed and ball-milled for 20-30 min to obtain a composite conductive filler. The composite conductive filler was added to a mixed solution of anhydrous ethanol and deionized water and ultrasonically dispersed for 10-15 min. Silane coupling agent KH-560 was added, and the pH was adjusted to 8-9. The mixture was stirred at 60-70℃ and 300-400 rpm for 6-8 h. After the reaction was completed, the mixture was filtered and vacuum dried at 70-80℃ for 6-8 h to obtain KH-560 modified conductive agent. The mass ratio of conductive carbon black, carboxylated carbon nanotubes, and silane coupling agent KH-560 is (7-9):(1-3):(0.5-0.7).

6. The method for preparing a high-adhesion current collector according to claim 1, characterized in that: By weight, the metal-organic binder comprises 80-90 parts of PI-PU block copolymer, 10-15 parts of KH-560 modified nanocomposite filler, 6-10 parts of KH-560 modified conductive agent, and 4-8 parts of cyclic polycarbonate.

7. The method for preparing a high-adhesion current collector according to claim 1, characterized in that: The preparation method of the pretreated base film is as follows: The base film was sequentially immersed in anhydrous ethanol and deionized water, and ultrasonically cleaned for 5-10 minutes each. After cleaning, it was removed and vacuum dried at 70-80℃ for 30-40 minutes. It was then transferred to a plasma treatment device and evacuated to a vacuum of 1×10⁻⁶. -3 Pa-5×10 -3 Pa, argon gas is introduced for plasma cleaning, with the argon gas flow rate set to 40-50 sccm, the power supply to 100-120W, and the cleaning time to 3-5 min. After cleaning, oxygen is introduced for plasma activation, with the argon gas flow rate set to 30-40 sccm, the oxygen flow rate to 10-20 sccm, the power supply to 80-100W, and the activation time to 2-4 min, to obtain the pretreated base film.

8. The method for preparing a high-adhesion current collector according to claim 1, characterized in that: The preparation method of the high-adhesion current collector is as follows: Using a dispensing machine, apply metal-organic adhesive to the pretreated base film and dry at 80-100℃ for 5-10 minutes. Then, hot press it with a metal foil, setting the hot pressing temperature to 120-130℃, the hot pressing pressure to 0.3-0.5MPa, and the hot pressing time to 3-5 minutes to form a metal foil-organic layer structure. A metal layer is deposited by magnetron sputtering on the organic layer side of the metal foil-organic layer structure. The metal foil-organic layer structure is then transferred to the magnetron sputtering deposition equipment, and the vacuum is evacuated to 1×10⁻⁶. -3 Pa-5×10 -3 Pa, the substrate is preheated to 80-90℃, argon gas is introduced, the copper target power supply is started, the argon gas flow rate is set to 30sccm, the copper target power supply is 200W, and the deposition time is 120min, and a metal layer is deposited to obtain a high-binder current collector.

9. The method for preparing a high-adhesion current collector according to claim 8, characterized in that: After dispensing, the drying temperature is 80-100℃ and the time is 5-10 min. The hot-pressing process conditions include: hot-pressing temperature of 120-130℃, hot-pressing pressure of 0.3-0.5MPa, and hot-pressing time of 3-5 min. The magnetron sputtering process conditions include: argon flow rate of 20-30 sccm, copper target power supply of 180-200W, deposition time of 60-80 min, and the thickness of the formed metal layer is 3-4 μm.

10. The high-adhesion current collector prepared by the preparation method according to any one of claims 1-9, characterized in that: The current collector includes a metal foil, a metal layer, and an organic layer located between the metal foil and the metal layer. The area of ​​the organic layer is smaller than that of the metal foil, and the portion of the metal layer that does not overlap with the organic layer is deposited on the upper surface of the metal foil.

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