Composite current collector and preparation method and application thereof
By introducing phosphorus-containing monomers and coating with fluoropolymers and nanotube layers into the composite current collector, the problems of weak adhesion and poor corrosion resistance between the aluminum layer and the PET film are solved, achieving improvements in high adhesion, corrosion resistance, and conductivity.
Patent Information
- Application Number
- CN202511620927.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-07
- Publication Date
- 2026-02-17
AI Technical Summary
Existing composite aluminum foil current collectors in lithium-ion batteries suffer from weak interfacial bonding between the aluminum layer and the PET film, poor corrosion resistance, and complex processes that may compromise conductivity.
Phosphorus-containing monomers are introduced by plasma treatment to form coordination bonds between the aluminum conductive layer and the PET film. A fluoropolymer and nanotube composite layer is then coated on the surface of the aluminum conductive layer to form a three-dimensional conductive network.
It improves the adhesion between the aluminum conductive layer and the PET film, enhances corrosion resistance, reduces contact resistance, and improves conductivity and battery capacity retention.
Smart Images
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of batteries, in particular to a composite current collector and a preparation method and application thereof. BACKGROUND
[0002] The current collector is one of the indispensable electrode materials of lithium ion batteries, which has the important functions of bearing active materials (bearing property) and collecting micro-current (conductivity). Thinness and functionalization are the main development directions of the current collector. The composite current collector is a sandwich structure, the inner layer is a polymer macromolecule layer (such as PET, PP or PI), and the two sides are metal conductive layers (such as Al or Cu). In the current industrial production of composite current collectors, the composite aluminum foil usually uses 6um PET (polyethylene terephthalate) as the substrate, and then 1um aluminum layer is evaporated on both sides of the substrate. Although the PET composite aluminum foil can improve the flexibility, the interface bonding force between the aluminum layer and the PET film is weak, and the aluminum layer has poor corrosion resistance.
[0003] In the current technology, chemical etching treatment is used to improve the interface bonding force between the aluminum layer and the PET film, but the process is complex and the effect is limited, and organic coating is coated to resist corrosion, but the conductivity is sacrificed. SUMMARY
[0004] Therefore, the purpose of the present application is to provide a composite current collector and a preparation method and application thereof, which have high bonding force, corrosion resistance and conductivity.
[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: The present application first provides a composite current collector, which comprises: A film substrate, the surface of which is treated by plasma to introduce phosphorus-containing monomers; An aluminum conductive layer arranged on at least one side surface of the film substrate; and A surface functional layer arranged on the side surface of the aluminum conductive layer away from the film substrate, the surface functional layer comprising a fluorine-containing polymer layer and a nanotube composite layer arranged in turn from inside to outside.
[0006] As a further improvement of the above-mentioned scheme of the present application, the phosphorus-containing monomers are compounds represented by formula I, formula II or formula III: , ,
[0007] Wherein, R, R1, R2 are selected from one of alkyl, alkoxy, alkenyl, alkenyloxy, aryl, aryloxy, ester, amide, ether bond, (meth)acryloxy, isocyanate.
[0008] As a further improvement of the above-mentioned scheme of the present application, the phosphorus-containing monomers are , , , At least one of them.
[0009] The present invention also provides a method for preparing the composite current collector as described above, which includes the following steps: S1. After plasma treatment of the clean thin film, it is immersed in a phosphorus-containing monomer solution, a catalyst is added for reaction, and post-treatment is performed to obtain the thin film substrate; S2. An aluminum conductive layer is deposited on the surface of the thin film substrate by vapor deposition; S3. A fluoropolymer and a nanotube composite material are sequentially coated on the surface of the aluminum conductive layer and cured to form a surface functional layer on the surface of the aluminum conductive layer.
[0010] As a further improvement to the above-described solution of the present invention, the film is a PET film with a thickness of 4-10 μm, a PP film with a thickness of 6-10 μm, or a PI film with a thickness of 5-20 μm.
[0011] As a further improvement to the above-mentioned scheme of the present invention, in step S1, the plasma treatment is oxygen plasma treatment, which is performed at 50-100W for 1-5 minutes; the catalyst is...
[0012] As a further improvement to the above-mentioned solution of the present invention, in step S2, the thickness of the aluminum conductive layer is 1-2 μm.
[0013] As a further improvement to the above-mentioned scheme of the present invention, in step S3, the fluoropolymer is at least one of polytetrafluoroethylene, perfluoroethylene propylene, polyvinylidene fluoride, and polychlorotrifluoroethylene; the nanotube composite material is prepared from the following components in weight percentage: 0.1%-10% nanotubes, 70%-95% matrix material, 0.5%-5% dispersant, 0.5%-5% coupling agent, and the balance being solvent.
[0014] As a further improvement to the above-described solution of the present invention, the nanotube is selected from one of carbon nanotubes, boron-nitrogen nanotubes, TiO2 nanotubes, and cellulose nanotubes; The matrix material is selected from one of thermosetting resins, thermoplastic resins, elastomers, ceramic materials, and metallic materials; the ceramic material includes alumina or silicon carbide, and the metallic material is at least one of nickel, copper, and aluminum. The dispersant is selected from at least one of sodium dodecylbenzenesulfonate, sodium oleate, hexadecyltrimethylammonium bromide, sodium polystyrene sulfonate, and polyvinylpyrrolidone; The coupling agent is selected from at least one of stearic acid, maleic anhydride-grafted polyolefin, 3-aminopropyltriethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane. The solvent is selected from one of water, acetone, N-methylpyrrolidone, N,N-dimethylformamide, ethanol.
[0015] The application also provides a use of the composite current collector as described above in a lithium battery Compared with the prior art, the application has the following beneficial effects: The application introduces phosphorus-containing monomers (phosphoric acid groups and ester derivatives thereof) on the film substrate, and strong interaction occurs between the oxygen atoms or hydroxyl groups in the key functional groups of the phosphoric acid groups and ester derivatives thereof and metal ions to form a coordination bond, thereby enhancing the interfacial bonding force between the aluminum conductive layer and the PET film, passivating the aluminum conductive layer to form an aluminum oxide protective film, combining the surface functional layer, blocking the penetration of electrolyte, and improving corrosion resistance. DETAILED DESCRIPTION
[0016] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to specific embodiments. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.
[0017] Example 1 The present embodiment proposes a composite current collector, and a preparation method thereof includes the following steps: S1. The PET film substrate with a thickness of 10 μm is ultrasonically cleaned in ethanol for 15 min, then rinsed with deionized water, dried in a vacuum at 60°C, then O2 is introduced into a low-pressure radio frequency (RF) plasma system with a power of 50-100 W and a frequency of 13.56 MHz, and reacted for 5 min at a gas pressure of 0.1-1 mbar, then the activated PET film is immersed in a 4-(phosphoryloxy)phenylvinyl carbonate solution (10 wt%), a catalyst potassium persulfate is added, and oscillation reaction is carried out at 60°C under nitrogen protection for 4 hours, then the film substrate is obtained after being taken out and thoroughly rinsed with ethanol to remove the physical adsorbates; S2. 1 μm aluminum layers are respectively evaporated on both sides of the film substrate to obtain an aluminum conductive layer; S3. A 2 μm thick polytetrafluoroethylene and a 3 μm thick carbon nanotube composite material are coated on the surface of the aluminum conductive layer to form a surface functional layer, pre-cured in a 60°C low-temperature oven for 15 minutes, main cured by keeping warm at 150°C for 20 minutes and then slowly cooling, and the composite current collector is obtained by mechanical rolling. In the present embodiment, the nanotube composite material is prepared from the following components by weight percentage: 2% carbon nanotubes, 80% thermosetting resin matrix material, 1% sodium dodecylbenzenesulfonate dispersant, 25% maleic anhydride grafted polyolefin coupling agent, and the balance is an ethanol solvent.
[0018] Example 2 The present example proposes a composite current collector, the preparation method of which comprises the following steps: S1. The 10 μm thick PP film substrate was ultrasonically cleaned in ethanol for 15 min, then rinsed with deionized water, dried in vacuum at 60°C, and then introduced into an O2 atmosphere in a low-pressure RF plasma system at a power of 50-100 W and a frequency of 13.56 MHz, reacted for 5 min at a gas pressure of 0.1-1 mbar, immersed in a 4-((hydroxy(2-isocyanato-2-methoxyethoxy)phosphoryl)oxy)phenyl vinyl carbonate solution (10 wt%), added a catalyst of potassium persulfate, oscillated at 60°C under nitrogen protection for 4 hours, then removed and washed thoroughly with ethanol to remove the physically adsorbed substances, to obtain a film substrate; S2. A 1 μm thick aluminum layer was evaporated on both sides of the film substrate to obtain an aluminum conductive layer; S3. A 2 μm thick polyfluoroethylene propylene and a 3 μm thick carbon nanotube composite material were coated on the surface of the aluminum conductive layer to form a surface functional layer, pre-cured in a low-temperature oven at 60°C for 15 min, main cured by keeping at 150°C for 20 min and then slowly cooled, and mechanically rolled to obtain a composite current collector. In the present example, the nanotube composite material was prepared from the following components by weight percentage: 2% carbon nanotubes, 80% thermoplastic resin matrix material, 1% sodium polystyrene sulfonate dispersant, 25% maleic anhydride grafted polyolefin coupling agent, and the balance being an ethanol solvent.
[0019] Example 3 The present example proposes a composite current collector, the preparation method of which comprises the following steps: S1. The 10 μm thick PI film substrate was ultrasonically cleaned in ethanol for 15 min, then rinsed with deionized water, dried in vacuum at 60°C, and then introduced into an O2 atmosphere in a low-pressure RF plasma system at a power of 50-100 W and a frequency of 13.56 MHz, reacted for 5 min at a gas pressure of 0.1-1 mbar, immersed in a 2-methoxybutyl hydrogen (isocyanato) phosphonate solution (10 wt%), added a catalyst of potassium persulfate, oscillated at 60°C under nitrogen protection for 4 hours, then removed and washed thoroughly with ethanol to remove the physically adsorbed substances, to obtain a film substrate; S2. A 1 μm thick aluminum layer was evaporated on both sides of the film substrate to obtain an aluminum conductive layer; S3. A 2μm thick layer of polyvinylidene fluoride and a 3μm thick layer of carbon nanotube composite material are coated on the surface of the aluminum conductive layer to form a surface functional layer. Pre-curing: treatment in a 60°C low-temperature oven for 15 minutes; main curing: holding at 150°C for 20 minutes followed by slow cooling; mechanical rolling to obtain the composite current collector. In this embodiment, the nanotube composite material is prepared from the following components by weight percentage: 2% boron nitrogen nanotubes, 80% thermosetting resin matrix material, 1% sodium dodecylbenzenesulfonate dispersant, 25% maleic anhydride grafted polyolefin coupling agent, and the balance being water solvent.
[0020] Comparative Example 1 The difference between this comparative example and Example 1 is that step S3 was not performed in this comparative example.
[0021] Comparative Example 2 This embodiment proposes a composite current collector, the preparation method of which includes the following steps: S1. A 1μm aluminum layer is deposited on both sides of a 10μm thick PET film substrate to obtain an aluminum conductive layer; S3. A 2μm thick polytetrafluoroethylene and a 3μm thick carbon nanotube composite material are coated on the surface of the aluminum conductive layer to form a surface functional layer. Pre-curing: treatment in a 60°C low-temperature oven for 15 minutes; main curing: holding at 150°C for 20 minutes followed by slow cooling; mechanical rolling to obtain the composite current collector. In this embodiment, the nanotube composite material is prepared from the following components by weight percentage: 2% carbon nanotubes, 80% thermosetting resin matrix material, 1% sodium dodecylbenzenesulfonate dispersant, 25% maleic anhydride grafted polyolefin coupling agent, and the balance being ethanol solvent.
[0022] Comparative Example 3 This embodiment proposes a composite current collector, the preparation method of which includes the following steps: depositing 1μm aluminum layers on both sides of a 10μm thick PET film substrate to obtain a composite current collector.
[0023] Test case The composite current collectors prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests: conductivity was tested using the four-probe method, adhesion between the aluminum conductive layer and the thin film substrate was tested using the cross-cut method, and corrosion weight loss was tested after immersion in 1 mol / L lithium hexafluorophosphate electrolyte at 60°C for 30 days; and soft-pack batteries were prepared using the composite current collectors and constant current charge-discharge tests were conducted; the test results are shown in Table 1.
[0024] Table 1
[0025] According to the results in Table 1: Compared with Comparative Examples 1-2, Example 1 shows that coating the surface functional layer and introducing phosphorus-containing monomers can effectively improve the conductivity, bonding force and capacity retention of the composite current collector, and reduce the film surface corrosion weight loss rate. As can be seen from Examples and Comparative Example 3, the simultaneous introduction of phosphorus-containing monomers and coating functional layers has a better effect on improving the conductivity and bonding force of the composite current collector and reducing the film surface corrosion weight loss rate, and the capacity retention rate is increased from 85% to 92% or more.
[0026] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0027] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A composite current collector, characterized in that, It includes: A thin film substrate, the surface of which is introduced with phosphorus-containing monomers through plasma treatment; An aluminum conductive layer disposed on at least one surface of a thin film substrate; as well as A surface functional layer is provided on the side of the aluminum conductive layer away from the thin film substrate. The surface functional layer includes a fluoropolymer layer and a nanotube composite layer arranged sequentially from the inside to the outside.
2. The composite current collector according to claim 1, characterized in that, The phosphorus-containing monomer is a compound represented by Formula I, Formula II, or Formula III: 、 、 R, R1, and R2 are each selected from one of the following groups: alkyl, alkoxy, alkenyl, alkenyloxy, aryl, aryloxy, ester, amide, ether bond, (meth)acryloyloxy, and isocyanate group.
3. The composite current collector according to claim 1, characterized in that, The phosphorus-containing monomer is , , , At least one of them.
4. A method for preparing a composite current collector as described in any one of claims 1-3, characterized in that, It includes the following steps: S1. After plasma treatment of the clean thin film, it is immersed in a phosphorus-containing monomer solution, a catalyst is added for reaction, and post-treatment is performed to obtain the thin film substrate; S2. An aluminum conductive layer is deposited on the surface of the thin film substrate by vapor deposition; S3. A fluoropolymer and a nanotube composite material are sequentially coated on the surface of the aluminum conductive layer to form a surface functional layer on the surface of the aluminum conductive layer.
5. The method for preparing the composite current collector according to claim 4, characterized in that, The film is a PET film with a thickness of 4-10 μm, a PP film with a thickness of 6-10 μm, or a PI film with a thickness of 5-20 μm.
6. The method for preparing the composite current collector according to claim 4, characterized in that, In step S1, the plasma treatment is oxygen plasma treatment, performed at 50-100W for 1-5 minutes; the catalyst is...
7. The method for preparing the composite current collector according to claim 4, characterized in that, In step S2, the thickness of the aluminum conductive layer is 1-2 μm.
8. The method for preparing the composite current collector according to claim 4, characterized in that, In step S3, the fluoropolymer is at least one of polytetrafluoroethylene, perfluoroethylene propylene, polyvinylidene fluoride, and polychlorotrifluoroethylene; the nanotube composite material is prepared from the following components in weight percentage: 0.1%-10% nanotubes, 70%-95% matrix material, 0.5%-5% dispersant, 0.5%-5% coupling agent, and the balance being solvent.
9. The method for preparing the composite current collector according to claim 8, characterized in that, The nanotubes are selected from one of carbon nanotubes, boron-nitrogen nanotubes, TiO2 nanotubes, and cellulose nanotubes; The matrix material is selected from one of thermosetting resins, thermoplastic resins, elastomers, ceramic materials, and metallic materials; The dispersant is selected from at least one of sodium dodecylbenzenesulfonate, sodium oleate, hexadecyltrimethylammonium bromide, sodium polystyrene sulfonate, and polyvinylpyrrolidone; The coupling agent is selected from at least one of stearic acid, maleic anhydride-grafted polyolefin, 3-aminopropyltriethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane. The solvent is selected from one of water, acetone, N-methylpyrrolidone, N,N-dimethylformamide, and ethanol.
10. The application of a composite current collector as described in any one of claims 1-3 in a lithium battery.