Composite current collector and preparation method and application thereof

Abstract

The invention provides a composite current collector and a preparation method and application thereof. The composite current collector comprises a conductive layer, the conductive layer can generate microcracks in the needling process, the microcracks spread to generate large-area fracture, and the conductive layer is separated from steel needles. According to the composite current collector structure provided by the invention, the conductive layer generates microcracks in the needling process and rapidly spreads to generate large-area fracture, so that the conductive layer is separated from the steel needle, a closed loop formed by conduction of the positive and negative current collectors and thermal runaway of the battery caused by the closed loop are avoided, and the safety performance of the battery is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of new energy batteries and relates to a composite current collector and a preparation method and application thereof. Background Art

[0002] At present, composite current collectors based on polymer films have received widespread attention and application in the new energy industry. The preparation of the composite current collector usually uses a physical vapor deposition (PVD) method to deposit a layer of metal on a polymer film (such as polyesters, polyolefins, etc.) to prepare a composite current collector with good conductivity. Compared with traditional current collectors, composite current collectors based on polymer films have the characteristics of low cost, light weight, and good internal insulation. These characteristics enable the composite current collector to reduce the cost of the battery and improve the energy density and safety of the battery when used in the battery.

[0003] The current composite current collector mainly relies on the insulation and flame retardant properties of the intermediate layer, namely the polymer film layer, to improve the safety of the battery. However, although this improves the safety performance of the battery, the improvement is limited.

[0004] Therefore, providing a current collector structure with high safety performance and without affecting battery performance is a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a composite current collector and a preparation method and application thereof. The composite current collector structure provided by the present invention generates microcracks in the conductive layer during the needle puncture process, which quickly spreads and causes large-area fractures, thereby achieving separation of the conductive layer from the steel needle, avoiding the formation of a closed loop by the positive and negative current collectors and the resulting thermal runaway of the battery, thereby greatly improving the safety performance of the battery.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a composite current collector, which includes a conductive layer. Microcracks will be generated in the conductive layer during the needle puncture process, and the microcracks will spread and cause large-area fracture, thereby achieving separation of the conductive layer from the steel needle.

[0008] The composite current collector structure provided by the present invention has a conductive layer in which microcracks are generated during the needle puncture process and quickly spread to cause large-area fractures, thereby achieving separation of the conductive layer from the steel needle, avoiding the formation of a closed loop due to conduction between the positive and negative current collectors and the resulting thermal runaway of the battery, thereby improving the safety performance of the battery and promoting the promotion and application of the composite current collector.

[0009] Preferably, the composite current collector comprises a base film and a functional layer located on at least one side of the base film; the functional layer comprises a conductive layer; and the conductive layer comprises alternately stacked metal layers and intermediate layers.

[0010] The composite current collector structure provided by the present invention can generate microcracks in the conductive layer during the needle puncture process through the coordinated cooperation of various structural layers in the functional layer, and quickly spread to cause large-area fractures, thereby achieving separation of the conductive layer from the steel needle, avoiding the formation of a closed loop by the positive and negative current collectors and the resulting thermal runaway of the battery, thereby improving the safety performance of the battery and promoting the promotion and application of the composite current collector.

[0011] The intermediate layer in the conductive layer inhibits the continuous growth of the metal layer grains, and prepares a conductive layer with non-penetrating, small-sized metal grains, thereby ensuring that the cracks generated in the conductive layer during the needle puncture process are easy to spread over a large area, thereby causing a large-area break of the conductive layer, avoiding the battery safety problems caused by the conduction of the positive and negative current collectors. If the conductive layer only contains a metal layer, the cracks generated during the needle puncture process cannot spread over a large area; and the intermediate layer and the metal layer are both non-porous structures. If they are connected to each other through pores, the continuous growth of the metal layer grains cannot be inhibited, which is not conducive to improving the safety performance of the battery; the protective layer isolates the direct contact between the electrolyte and the conductive layer, avoiding the erosion of the electrolyte.

[0012] Preferably, the base film has a thickness of 1 to 10 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm.

[0013] Preferably, the material of the base film includes any one of polyethylene terephthalate, polypropylene, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, polystyrene or polyimide, or a combination of at least two thereof.

[0014] The base film material in the present invention is not limited to the types of materials provided above, and the present invention is applicable to base film materials that can be used for current collector structures.

[0015] Preferably, a primer layer is provided between the base film and the conductive layer.

[0016] In the present invention, a primer layer is introduced into the functional layer to assist the conductive layer. The primer layer provides suitable bonding force between the conductive layer of the composite current collector and the polymer film, so that a certain relative movement occurs between the conductive layer and the polymer film during the deformation of the composite current collector, thereby promoting the deformation and fission of the conductive layer, thereby improving the safety performance of the battery. If the primer layer is missing, the safety performance of the battery will deteriorate.

[0017] Preferably, the adhesion between the primer layer and the conductive layer is 100 to 900 N / m, such as 100 N / m, 150 N / m, 200 N / m, 250 N / m, 300 N / m, 350 N / m, 400 N / m, 450 N / m, 500 N / m, 550 N / m, 600 N / m, 650 N / m, 700 N / m, 750 N / m, 800 N / m, 850 N / m, or 900 N / m, etc.

[0018] In the present invention, by adjusting the adhesion between the primer layer and the conductive layer, the relative movement between the base film and the conductive layer during the deformation process of the composite current collector is adjusted, thereby affecting the deformation and fission behavior of the conductive layer; if the adhesion is too small, the conductive layer is prone to excessive relative movement with the polymer film during the battery acupuncture process, which is not conducive to providing sufficient force along the surface for the conductive layer, inhibiting the large-area spread of cracks in the conductive layer, and weakening the safety performance of the battery; if it is too large, it is difficult for local micro-deformation to occur, which is not conducive to the large-area spread of cracks in the conductive layer and will also affect the safety performance of the battery.

[0019] Preferably, the material of the primer layer includes any one or a combination of at least two of alumina, silica, titanium oxide, nickel, chromium, titanium, nickel-chromium alloy, nickel-chromium-copper alloy, silicon-aluminum alloy, polyacrylic acid, polyacrylate, polyacrylamide, or polyurethane.

[0020] Preferably, the thickness of the conductive layer is 500 to 2000 nm, such as 500 nm, 600 nm, 800 nm, 900 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm, 1500 nm, 1800 nm, or 2000 nm, etc., and preferably 800 to 1200 nm.

[0021] In the present invention, when the thickness of the conductive layer is in the range of 500 to 2000 nm, a current collector structure with good conductive effect can be obtained, and it will not affect the normal performance of the battery energy density. If the composite conductive layer is too thin, the conductivity will be poor; if it is too thick, the prepared composite current collector will be too heavy, which is not conducive to improving the energy density of the battery. Considering the conductivity and taking into account the improvement of the energy density; further adjusting it to the thickness range of 800 to 1200 nm can ensure that the battery has good conductivity and also takes into account the improvement of the energy density.

[0022] Preferably, the thickness d1 of the metal layer satisfies: 20 < d1 ≤ 200 nm, such as 20 nm, 30 nm, 50 nm, 80 nm, 100 nm, 130 nm, 150 nm, 180 nm, or 200 nm, etc. In the present invention, if the metal layer is too thin, in order to ensure conductivity, the number of layers of the metal layer will be increased, which will seriously affect the production efficiency of the current collector.

[0023] Preferably, the thickness d2 of the intermediate layer satisfies: 1 nm≤d2≤10 nm, for example, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm.

[0024] Preferably, the thickness of the intermediate layer d2 is less than or equal to one tenth of the thickness of the metal layer d1.

[0025] In the present invention, the thickness of the intermediate layer d2 is less than or equal to one tenth of the thickness of the metal layer d1, which is more conducive to the composite current collector maintaining good conductivity.

[0026] Preferably, the number of metal layers in the conductive layer is n, the number of intermediate layers is n-1, and n satisfies: 5≤n≤40, for example, 5, 8, 10, 13, 15, 18, 20, 23, 25, 28, 30, 33, 35, 38 or 40, etc.

[0027] In the conductive layer mentioned in the present invention, the layered structure closer to the base layer and the protective layer can be a metal layer or an intermediate layer. Preferably, the metal layer structure is in direct contact with the base layer and the protective layer. The stacked structure can better improve the safety performance of the battery. Furthermore, if the number of metal layers is too small, less than 5 layers, the prepared composite current collector will have a poor effect on improving the safety of the battery. If it is greater than 40 layers, the battery safety performance cannot be further improved, and the production efficiency is low, which increases the difficulty of production.

[0028] Preferably, the average particle size of the metal grains in the metal layer is ≤200nm, for example, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 130nm, 150nm, 180nm or 200nm, etc., preferably 10-100nm.

[0029] In the present invention, the metal grains are columnar crystals, and the average grain size of the grains is the diameter of the columnar crystals, not the average grain size of the length. The average grain size of the metal grains in the metal layer will affect the generation of microcracks in the conductive layer. If the average grain size is too large, the plasticity of the metal layer will become stronger, which is not conducive to the large-area fission of the metal layer during the needle puncture process, thereby making the prepared composite current collector less effective in improving the safety of the battery; when further adjusted to 10 to 100 nm, the generation of microcracks in the conductive layer can be achieved without increasing the difficulty of preparation, thereby achieving a significant improvement in the safety performance of the composite current collector.

[0030] Preferably, the metal in the metal layer includes any one of aluminum, copper, gold, silver, nickel or zinc and alloys thereof, or a combination of at least two thereof.

[0031] Preferably, the material of the intermediate layer includes any one of alloy, nitride, carbide, sulfide, fluoride, silicide or phosphide or a combination of at least two thereof, preferably any one of carbide, silicide or fluoride or a combination of at least two thereof.

[0032] Preferably, the alloy in the intermediate layer includes any one of nickel-chromium alloy, nickel-chromium-copper alloy, nickel-chromium-silicon alloy, nickel-chromium-cobalt alloy, silicon-aluminum alloy, aluminum-silicon-copper alloy, copper-nickel alloy, copper-nickel-titanium alloy, copper-gallium alloy, copper-indium alloy, copper-indium-gallium alloy, aluminum-tin-copper alloy, aluminum-chromium alloy, tungsten-titanium alloy, molybdenum-copper alloy, molybdenum-niobium alloy, molybdenum-tantalum alloy, molybdenum-zirconium-titanium alloy or molybdenum-lanthanum alloy, or a combination of at least two of them.

[0033] Preferably, the nitride includes any one of aluminum nitride, boron nitride, chromium nitride, titanium nitride, silicon nitride, niobium nitride, zirconium nitride, hafnium nitride, tantalum nitride, vanadium nitride or aluminum titanium nitride, or a combination of at least two thereof.

[0034] Preferably, the carbide includes any one of aluminum carbide, boron carbide, chromium carbide, nickel carbide, tungsten carbide, titanium carbide, hafnium carbide, zirconium carbide, tantalum carbide, lanthanum carbide, molybdenum carbide, niobium carbide, silicon carbide, titanium carbide or vanadium carbide, or a combination of at least two thereof.

[0035] Preferably, the sulfide includes any one of copper sulfide, tin sulfide, zinc sulfide, tungsten sulfide, molybdenum sulfide, iron sulfide, antimony sulfide, chromium sulfide, nickel sulfide, titanium sulfide, aluminum copper sulfide or iron copper sulfide, or a combination of at least two thereof.

[0036] Preferably, the fluoride includes any one of iridium fluoride, magnesium fluoride, calcium fluoride, lithium fluoride, aluminum fluoride, barium fluoride, samarium fluoride, cerium fluoride, yttrium fluoride or scandium fluoride, or a combination of at least two thereof.

[0037] Preferably, the silicide includes any one of cobalt silicide, chromium silicide, nickel silicide, titanium silicide, hafnium silicide, molybdenum silicide, niobium silicide, tantalum silicide, vanadium silicide, tungsten silicide or zirconium silicide, or a combination of at least two thereof.

[0038] Preferably, the phosphide is any one of aluminum phosphide, boron phosphide, copper phosphide, nickel phosphide, silicon phosphide, tungsten phosphide, gallium phosphide, germanium phosphide, indium phosphide, molybdenum phosphide, niobium phosphide or tantalum phosphide, or a combination of at least two thereof.

[0039] Preferably, a protective layer is further provided on the surface of the conductive layer away from the base film.

[0040] Preferably, the thickness of the protective layer is 10 to 100 nm, for example, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm, etc., preferably 20 to 80 nm.

[0041] Preferably, the material of the protective layer includes any one of nickel, chromium, nickel-based alloy, copper-based alloy, copper oxide, aluminum oxide, nickel oxide, chromium oxide, cobalt oxide, copper chromium oxide, graphite, carbon black, carbon nano-quantum dots, carbon nanotubes, carbon nanofibers, graphene or graphene oxide, or a combination of at least two of them.

[0042] In a second aspect, the present invention provides a method for preparing the composite current collector as described in the first aspect, the preparation method comprising the following steps:

[0043] A conductive layer is composited on the surface of at least one side of the base film; wherein the conductive layer comprises metal layers and intermediate layers which are alternately stacked.

[0044] Preferably, a primer layer is provided between the base film and the conductive layer.

[0045] Preferably, the composite method of the base layer includes magnetron sputtering and / or coating.

[0046] Preferably, the composite preparation method of the metal layer includes evaporation and / or magnetron sputtering.

[0047] Preferably, the preparation method of the intermediate layer comprises physical vapor deposition.

[0048] Preferably, after the conductive layer is obtained by compounding, a protective layer is further provided on the surface of the conductive layer away from the base film.

[0049] Preferably, the composite preparation method of the protective layer includes any one of physical vapor deposition, chemical vapor deposition, in-situ forming or coating, or a combination of at least two of them.

[0050] In the preparation method of the composite current collector provided by the present invention, the preparation process thereof is all conventional technical means, and those skilled in the art can make adaptive selection of the preparation method and adaptive adjustment of the parameters according to actual needs.

[0051] In a third aspect, the present invention further provides a battery, wherein the battery comprises the composite current collector as described in the first aspect.

[0052] The battery provided by the present invention includes a lithium ion battery and / or a sodium ion battery. Except for the composite current collector provided by the present invention, the remaining materials, structures and preparation methods are all selected according to conventional technologies.

[0053] Preferably, the composite current collector is used in an electrode plate of the battery.

[0054] The composite current collector provided by the present invention can be used in both positive electrode sheets and negative electrode sheets, and those skilled in the art can make an adaptive selection according to the needs.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] The composite current collector structure provided by the present invention can generate microcracks in the conductive layer during the needle puncture process through the coordinated cooperation of various structural layers in the functional layer, and quickly spread to cause large-area fractures, thereby achieving separation of the conductive layer from the steel needle, avoiding the formation of a closed loop by the positive and negative current collectors and the resulting thermal runaway of the battery, thereby improving the safety performance of the battery and promoting the promotion and application of the composite current collector. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a schematic diagram of the structure of the composite current collector provided in Example 1.

[0058] Among them, 1-base film, 2-base layer, 3-conductive layer, 4-protective layer. DETAILED DESCRIPTION

[0059] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0060] In a specific embodiment, the present invention provides a method for preparing a composite current collector, the preparation method comprising the following steps:

[0061] (1) placing the base film in a magnetron sputtering machine, using the base material as a target material, adjusting the power, gas flow, vacuum degree and time during the sputtering process, and depositing the base layer on the surface of the base film;

[0062] (2) Compounding a conductive layer on the surface of the base layer according to the stacking sequence of the conductive layer (i.e. the number and alternating sequence of the metal layer and the intermediate layer):

[0063] The preparation of the metal layer includes:

[0064] a. Evaporation method: the conditions for preparing the metal layer are: the raw material is high-purity metal wire (purity ≥ 99.9%), the heating temperature is greater than the melting point of the metal wire, the vacuum degree of the vacuum chamber is less than or equal to 0.05Pa, the coating time each time is 0.5-100s, and the main roller cooling temperature is -30℃-10℃;

[0065] b. Magnetron sputtering method: For magnetron sputtering, the conditions for preparing the metal layer are: the target material is a target material of the metal layer material (purity ≥ 99.9%), the target power supply is a DC power supply, the target power is 5-20kW, the vacuum degree of the vacuum chamber is less than or equal to 0.1Pa, the gas source is argon, the argon flow rate is 20-500mL / min, each coating time is 0.1-120s, and the main roller cooling temperature is -20℃-30℃;

[0066] The preparation of the middle layer includes:

[0067] Magnetron sputtering method: The target material is a high-purity target material (purity ≥ 99.9%), and the material is the alloy, nitride, sulfide, fluoride, silicide, phosphide, etc. as mentioned above. The target power of the target power supply is 1-10kW, the vacuum degree of the vacuum chamber is less than or equal to 0.1Pa, the gas source is argon, the argon flow rate is 10-500mL / min, and the coating time for each time is 0.1-10s;

[0068] (3) A composite protective layer is formed on the surface of the conductive layer.

[0069] The following examples and comparative examples are all prepared based on the preparation method specifically provided above.

[0070] Example 1

[0071] This embodiment provides a composite current collector, such as Figure 1 As shown, the composite current collector includes a base film 1 (PET film) and functional layers located on both sides of the base film 1 (i.e., functional layers are provided on both sides of the base film); along the direction from close to the base film 1 to far away from the base film 1, the functional layer includes a base layer 2 (nickel-chromium alloy), a conductive layer 3 (thickness of 1030nm) and a protective layer 4 (copper-chromium oxide) stacked in sequence; the conductive layer 3 includes alternately stacked metal layers (copper) and intermediate layers (nickel-chromium-copper layers), the number of metal layers is 9 layers, and the number of intermediate layers is 8 layers, that is, the metal layer in the conductive layer 4 is in direct contact with the base layer and the protective layer;

[0072] The preparation method of the composite current collector is as follows, based on the preparation method provided in the above specific embodiment:

[0073] (1) preparing a primer layer, placing a biaxially stretched PET film with a thickness of 6 μm in a magnetron sputtering machine, using a nickel-chromium alloy target as a target material, and depositing a 5 nm primer layer on both sides of the PET film. The specific process conditions are: using a nickel-chromium target (purity: 99.99%) as a target material, a target power of 5.0 kW, an argon gas flow rate of 50 mL / min, a coating vacuum of 0.08 Pa, and a coating time of 1 s, thereby preparing a PET composite film with a primer layer on the surface;

[0074] (2) Preparing a conductive layer (metal layer and intermediate layer are arranged alternately), placing the above-prepared PET composite film with a base layer on the surface into a magnetron sputtering machine, and depositing copper, nickel-chromium-copper on the surface of the composite film in sequence, wherein: ① Metal layer: The metal layer is a copper layer with a thickness of 110 nm, 9 layers, and an average size of copper grains in the metal layer of 30 nm. The preparation conditions of each layer are: using a copper target (purity: 99.99%) as the target material, the target power is 12.0 kW, the argon gas flow rate is 50 mL / min, and the coating vacuum is 0.08Pa, the cooling temperature of the main roller during the coating process is -10℃, and the coating time is 11s; ②Intermediate layer: The intermediate layer is a nickel-chromium-copper layer with a thickness of 5nm and 8 layers. The preparation conditions of each layer are: nickel-chromium-copper target (purity: 99.99%) is used as the target material, the target power is 4.5kW, the argon flow rate is 50mL / min, the coating vacuum degree is 0.08Pa, the cooling temperature of the main roller during the coating process is -20℃, and the coating time is 1s, that is, a PET composite film including a base layer and a conductive layer is prepared;

[0075] (3) Preparing a protective layer, the PET composite film comprising a base layer and a conductive layer prepared above was immersed in a 0.5 g / L chromic anhydride aqueous solution (25° C.) for 20 seconds, and then washed with a pure water tank. After washing, it was placed in an oven at 60° C. for drying to obtain a finished composite current collector. The bonding force between the conductive layer and the base film in the prepared composite current collector was 500 N / m.

[0076] Example 2

[0077] The difference between this embodiment and embodiment 1 is that the material of the intermediate layer in this embodiment is aluminum nitride.

[0078] The preparation process of the intermediate layer is as follows: aluminum nitride target (purity: 99.99%) is used as the target material, the target power is 6.0kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 1s, and the main roller cooling temperature during the coating process is -20°C.

[0079] The rest of the structure and preparation process are consistent with those in Example 1.

[0080] Example 3

[0081] The difference between this embodiment and embodiment 1 is that the material of the intermediate layer in this embodiment is chromium carbide.

[0082] The preparation process of the intermediate layer is as follows: using chromium carbide target (purity: 99.99%) as the target material, the target power is 5.6kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 1s, and the main roller cooling temperature during the coating process is -20°C.

[0083] The rest of the structure and preparation process are consistent with those in Example 1.

[0084] Example 4

[0085] The difference between this embodiment and embodiment 1 is that the material of the intermediate layer in this embodiment is magnesium fluoride.

[0086] The preparation process of the intermediate layer is as follows: magnesium fluoride target (purity: 99.99%) is used as the target material, the target power is 6.5kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 1s, and the main roller cooling temperature during the coating process is -20°C.

[0087] The rest of the structure and preparation process are consistent with those in Example 1.

[0088] Example 5

[0089] The difference between this embodiment and Embodiment 1 is that the material of the intermediate layer in this embodiment is nickel silicide.

[0090] The preparation process of the intermediate layer is as follows: nickel silicide target (purity: 99.99%) is used as the target material, the target power is 5.8kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 1s, and the main roller cooling temperature during the coating process is -20°C.

[0091] The rest of the structure and preparation process are consistent with those in Example 1.

[0092] Example 6

[0093] The difference between this embodiment and embodiment 1 is that the material of the intermediate layer in this embodiment is aluminum phosphide.

[0094] The preparation process of the intermediate layer is as follows: aluminum phosphide target (purity: 99.99%) is used as the target material, the target power is 7.0kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 1s, and the main roller cooling temperature during the coating process is -20°C.

[0095] The rest of the structure and preparation process are consistent with those in Example 1.

[0096] Example 7

[0097] The difference between this embodiment and embodiment 1 is that the material of the intermediate layer in this embodiment is a mixture of nickel-chromium-copper and aluminum nitride.

[0098] The preparation process of the intermediate layer is as follows: using a nickel-chromium-copper and aluminum nitride mixture target (purity: 99.99%) as the target material, the target power is 5.0kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 1s, and the main roller cooling temperature during the coating process is -20°C.

[0099] The rest of the structure and preparation process are consistent with those in Example 1.

[0100] Example 8

[0101] The difference between this embodiment and embodiment 1 is that the material of the intermediate layer in this embodiment is a mixture of magnesium fluoride and chromium carbide.

[0102] The preparation process of the intermediate layer is as follows: using a mixture of magnesium fluoride and chromium carbide (purity: 99.99%) as the target material, the target power is 6.2kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 1s, and the main roller cooling temperature during the coating process is -20°C.

[0103] The rest of the structure and preparation process are consistent with those in Example 1.

[0104] Example 9

[0105] The difference between this embodiment and embodiment 1 is that the material of the intermediate layer in this embodiment is a mixture of aluminum nitride and chromium carbide.

[0106] The preparation process of the intermediate layer is as follows: using aluminum nitride and chromium carbide mixture target (purity: 99.99%) as the target material, the target power is 6.0kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 1s, and the main roller cooling temperature during the coating process is -20°C.

[0107] The rest of the structure and preparation process are consistent with those in Example 1.

[0108] Example 10

[0109] The difference between this embodiment and Embodiment 1 is that the material of the metal layer in this embodiment is metal aluminum.

[0110] The preparation process of the metal layer is as follows: aluminum target (purity: 99.99%) is used as the target material, the target power is 10.0kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 10s, and the main roller cooling temperature during the coating process is -10°C.

[0111] The rest of the structure and preparation process are consistent with those in Example 1.

[0112] Embodiment 11

[0113] The difference between this embodiment and embodiment 1 is that in this embodiment, the thickness of the metal layer is 60 nm, and the thickness of the conductive layer is 580 nm.

[0114] The preparation process of the metal layer is as follows: copper target (purity: 99.99%) is used as the target material, the target power is 12kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 6s, and the main roller cooling temperature during the coating process is -10°C.

[0115] The rest of the structure and preparation process are consistent with those in Example 1.

[0116] Example 12

[0117] The difference between this embodiment and embodiment 1 is that in this embodiment, the thickness of the metal layer is 200 nm, and the thickness of the conductive layer is 1840 nm.

[0118] The preparation process of the metal layer is as follows: copper target (purity: 99.99%) is used as the target material, the target power is 12kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 20s, and the main roller cooling temperature during the coating process is -10°C.

[0119] The rest of the structure and preparation process are consistent with those in Example 1.

[0120] Example 13

[0121] The difference between this embodiment and embodiment 1 is that in this embodiment, the thickness of the metal layer is 220 nm, the number of layers is 5, the number of layers of the intermediate layer is 4, and the thickness of the conductive layer is 1120 nm.

[0122] The preparation process of the metal layer is as follows: copper target (purity: 99.99%) is used as the target material, the target power is 12kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 22s, and the main roller cooling temperature during the coating process is -10°C.

[0123] The rest of the structure and preparation process are consistent with those in Example 1.

[0124] Embodiment 14

[0125] The difference between this embodiment and embodiment 1 is that the average grain size of the metal grains in the metal layer in this embodiment is 100 nm.

[0126] The preparation process of the metal layer is as follows: copper target (purity: 99.99%) is used as the target material, the target power is 10.0kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 14s, and the main roller cooling temperature during the coating process is 1°C.

[0127] The rest of the structure and preparation process are consistent with those in Example 1.

[0128] Embodiment 15

[0129] The difference between this embodiment and embodiment 1 is that the average grain size of the metal grains in the metal layer in this embodiment is 200 nm.

[0130] The preparation process of the metal layer is as follows: copper target (purity: 99.99%) is used as the target material, the target power is 8.0kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 17s, and the main roller cooling temperature during the coating process is 10°C.

[0131] The rest of the structure and preparation process are consistent with those in Example 1.

[0132] Example 16

[0133] The difference between this embodiment and embodiment 1 is that the average grain size of the metal grains in the metal layer in this embodiment is 220 nm.

[0134] The preparation process of the metal layer is as follows: copper target (purity: 99.99%) is used as the target material, the target power is 7.0kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 19s, and the main roller cooling temperature during the coating process is 12°C.

[0135] The rest of the structure and preparation process are consistent with those in Example 1.

[0136] Embodiment 17

[0137] The difference between this embodiment and embodiment 1 is that in the conductive layer of this embodiment, the number of intermediate layers is 9, and the number of metal layers is 8, that is, the intermediate layer in the conductive layer is in direct contact with the base layer and the protective layer, and the thickness of the conductive layer is 925nm.

[0138] During the preparation process, the intermediate layer is first deposited on the surface of the base layer.

[0139] The rest of the structure and preparation process are consistent with those in Example 1.

[0140] Embodiment 18

[0141] The difference between this embodiment and embodiment 1 is that in the conductive layer of this embodiment, there are 5 metal layers, 4 intermediate layers, and the thickness of the conductive layer is 570 nm.

[0142] The rest of the structure and preparation process are consistent with those in Example 1.

[0143] Embodiment 19

[0144] The difference between this embodiment and embodiment 11 is that in the conductive layer of this embodiment, the metal layer has 20 layers with a thickness of 60 nm, the intermediate layer has 19 layers with a thickness of 5 nm, and the conductive layer has a thickness of 1295 nm.

[0145] The rest of the structure and preparation process are consistent with Example 11.

[0146] Embodiment 20

[0147] The difference between this embodiment and embodiment 1 is that in the conductive layer of this embodiment, there are 40 metal layers and 39 intermediate layers, the thickness of the metal layer is 20 nm, the thickness of the intermediate layer is 2 nm, and the thickness of the conductive layer is 878 nm.

[0148] The preparation conditions of the metal layer are: copper target (purity: 99.99%) as the target material, target power of 12.0 kW, argon flow rate of 50 mL / min, coating vacuum of 0.08 Pa, coating time of 2.0 s, and the temperature of the main roller during the coating process of -10 °C.

[0149] The preparation conditions of the intermediate layer are as follows: nickel-chromium-copper target (purity: 99.99%) is used as the target material, the target power is 2.0 kW, the argon flow rate is 50 mL / min, the coating vacuum is 0.08 Pa, the main roller cooling temperature during the coating process is -10°C, and the coating time is 1 s, that is, a PET composite film including a base layer and a conductive layer is prepared;

[0150] The rest of the structure and preparation process are consistent with those in Example 1.

[0151] Embodiment 21

[0152] The difference between this embodiment and embodiment 20 is that in the conductive layer of this embodiment, the metal layer is 45 layers, the intermediate layer is 44 layers, and the thickness of the conductive layer is 988 nm.

[0153] The rest of the structure and preparation process are consistent with Example 20.

[0154] Embodiment 22

[0155] The difference between this embodiment and embodiment 12 is that in the conductive layer of this embodiment, there are 4 metal layers, 3 intermediate layers, and the thickness of the conductive layer is 815 nm.

[0156] The rest of the structure and preparation process are consistent with Example 12.

[0157] Embodiment 23

[0158] The difference between this embodiment and embodiment 1 is that in the conductive layer of this embodiment, the thickness of the intermediate layer is 0.5 nm.

[0159] The preparation process of the intermediate layer is as follows: nickel-chromium-copper target (purity: 99.99%) is used as the target material, the target power is 2.0kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 0.25s, and the main roller cooling temperature during the coating process is -20°C.

[0160] The rest of the structure and preparation process are consistent with those in Example 1.

[0161] Embodiment 24

[0162] The difference between this embodiment and embodiment 1 is that in the conductive layer of this embodiment, the thickness of the intermediate layer is 1 nm.

[0163] The preparation process of the intermediate layer is as follows: nickel-chromium-copper target (purity: 99.99%) is used as the target material, the target power is 2.0kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 0.5s, and the main roller cooling temperature during the coating process is -20°C.

[0164] The rest of the structure and preparation process are consistent with those in Example 1.

[0165] Embodiment 25

[0166] The difference between this embodiment and embodiment 1 is that in the conductive layer of this embodiment, the thickness of the intermediate layer is 10 nm.

[0167] The preparation process of the intermediate layer is as follows: nickel-chromium-copper target (purity: 99.99%) is used as the target material, the target power is 4.5kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 2s, and the main roller cooling temperature during the coating process is -20°C.

[0168] The rest of the structure and preparation process are consistent with those in Example 1.

[0169] Embodiment 26

[0170] The difference between this embodiment and embodiment 1 is that the base layer in this embodiment is titanium.

[0171] The preparation process of the base layer is as follows: titanium target (purity: 99.99%) is used as the target material, the target power is 4.8kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 1s, and the main roller cooling temperature during the coating process is -20°C. The bonding strength between the conductive layer and the base film in the prepared composite current collector is 100N / m.

[0172] The rest of the structure and preparation process are consistent with those in Example 1.

[0173] Embodiment 27

[0174] The difference between this embodiment and embodiment 1 is that the bottom layer in this embodiment is silicon oxide.

[0175] The preparation process of the bottom layer is as follows: silicon oxide target (purity: 99.99%) is used as the target material, the target power is 6kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 1s, and the main roller cooling temperature during the coating process is -20°C. The bonding force between the conductive layer and the base film in the prepared composite current collector is 900N / m.

[0176] The rest of the structure and preparation process are consistent with those in Example 1.

[0177] Embodiment 28

[0178] The difference between this embodiment and embodiment 1 is that a porous PET film (average pore size of 0.2 micrometers) is used in this embodiment, and the bonding force between the conductive layer and the base film in the prepared composite current collector is 1000 N / m.

[0179] The rest of the structure and preparation process are consistent with those in Example 1.

[0180] Embodiment 29

[0181] The difference between this embodiment and embodiment 1 is that the functional layer structure in this embodiment is located on one side surface of the base film.

[0182] The rest of the structure and preparation process are consistent with those in Example 1.

[0183] Embodiment 30

[0184] The difference between this embodiment and embodiment 1 is that this comparative example does not have a primer layer, and the bonding force between the conductive layer and the base film is 50 N / m.

[0185] The rest of the structure and preparation process are consistent with those in Example 1.

[0186] Comparative Example 1

[0187] The difference between this comparative example and Example 1 is that the conductive layer of this comparative example does not contain an intermediate layer (ie, the conductive layer is a pure metal layer), and the thickness of the metal layer is 1030 nm.

[0188] The preparation process of the metal layer is as follows: using copper target (purity: 99.99%) as the target material, the target power is 12.0kW, the argon flow rate is 50mL / min, the coating vacuum is 0.08Pa, the coating time is 103s, and the temperature of the main roller during the coating process is -10°C.

[0189] The rest of the structure and preparation process are consistent with those in Example 1.

[0190] The performance of the composite current collectors provided in Examples 1-30 and Comparative Example 1 was tested:

[0191] 1. Square resistance: Place the prepared flat composite current collector sample on the sample stage and use a four-probe square resistance meter to test the square resistance of the sample.

[0192] 2. Safety performance:

[0193] ①Battery assembly:

[0194] ⅰ. For lithium-ion battery assembly based on composite aluminum current collector: For the positive electrode, the positive electrode current collector adopts the composite aluminum (ie, the metal element in the metal layer is aluminum) current collector prepared by the present invention (Example 11), and the positive electrode material adopts LiNi 0.6 Mn 0.2 Co 0.2 O2 (NCM622); for the negative electrode: the negative electrode current collector adopts traditional copper foil (thickness is 6 microns), and the negative electrode material adopts artificial graphite; for the diaphragm, alumina ceramic coated polyethylene diaphragm (thickness is 25 microns) is adopted; for the electrolyte, 1 mol / L LiPF6 carbonate solution is adopted, and the carbonate is propylene carbonate, ethylene carbonate, and ethyl methyl carbonate, and the mass ratio of the three is 1:1:1; the above materials are used to assemble the lithium-ion battery according to the relevant process.

[0195] ⅱ. For lithium-ion battery assembly based on composite copper current collector (i.e. the metal element in the metal layer is copper): for the positive electrode, the positive electrode current collector adopts a traditional aluminum current collector (thickness of 13 microns), and the positive electrode material adopts LiNi 0.6 Mn 0.2 Co 0.2 O2 (NCM622); for the negative electrode: the negative electrode current collector adopts the composite copper current collector prepared by the present invention, and the negative electrode material adopts artificial graphite; for the diaphragm, an alumina ceramic-coated polyethylene diaphragm (thickness is 25 microns) is adopted; for the electrolyte, a 1 mol / L LiPF6 carbonate solution is adopted, and the carbonates are propylene carbonate, ethylene carbonate, and ethyl methyl carbonate, and the mass ratio of the three is 1:1:1; the above materials are used to assemble a lithium-ion battery according to the relevant process.

[0196] ② Safety performance test: The safety performance of the battery is verified by a needle puncture test, as follows: the battery prepared above is placed in a needle puncture test device, where the diameter of the needle is 3mm, the puncture speed is 10mm / s, the sampling interval is 100ms, and the sampling time is 15min. The maximum temperature of the battery after heating during the puncture process and the battery voltage after the puncture are recorded to characterize the safety performance of the battery. The lower the maximum temperature and the higher the battery voltage after puncture, the better the battery safety performance.

[0197] Table 1 shows the specific test results of the above tests.

[0198] Table 1

[0199]

[0200]

[0201]

[0202] It can be seen from the test results of Examples 1-29 and Comparative Example 1 that, compared with the traditional composite current collector, the safety performance of the battery based on the composite current collector proposed in the present invention is significantly improved.

[0203] It can be seen from the test results of Examples 1-9 that, compared with a composite current collector whose intermediate layer is a single substance, a composite current collector whose intermediate layer is a combination of substances has a better effect on improving battery safety performance.

[0204] From the test results of Examples 1 and 11-13, it can be seen that with the increase in the thickness of the metal layer, the safety performance of the battery based on the prepared composite current collector first increases and then decreases. However, when the thickness exceeds a certain range, the safety performance deteriorates significantly. This is because the metal layer is too thick, resulting in the length of the columnar crystals in the layer being too long, and cracks are not easy to spread during the needle puncture process.

[0205] From the test results of Example 1 and Examples 14-16, it can be seen that the larger the average particle size of the metal grains in the metal layer, the greater the maximum temperature rise of the battery during the needling process and the greater the drop in the battery voltage after the needling, that is, the battery safety performance deteriorates. This is because the smaller the grains, the more they can promote the propagation of microcracks generated in the metal layer during the needling process, and cause large-scale fractures, thereby separating the metal layer from the steel needle; while if the grains are too large, the plasticity of the metal layer will become stronger, which is not conducive to the large-scale fission of the metal layer during the needling process, thereby making the prepared composite current collector less effective in improving the safety of the battery.

[0206] Compared with Example 1, the maximum temperature rise of Example 17 during the needling process reaches 128°C, and the battery voltage is 0.9 after needling for 300s, and the safety performance is seriously deteriorated. This is because when the middle layer is in direct contact with the base layer, the adhesion between the metal layer and the polymer film is too high, and local micro-deformation is not easy to occur during the needling process, which is not conducive to the diffusion of micro-cracks, and thus the safety performance cannot be improved.

[0207] From the test results of Example 1 and Examples 18-22, it can be seen that if the number of metal layers is too small, less than 5 layers, the maximum temperature rise during the puncture process will increase significantly, and the voltage after the puncture will decrease significantly, and the safety improvement effect will be seriously deteriorated; while if it is greater than 40 layers, the battery safety performance cannot be further improved, and the production efficiency will be affected and the production difficulty will be increased. Therefore, the preferred number of layers is in the range of 5-40 layers.

[0208] From the test results of Example 1 and Examples 23-25, it can be seen that within the appropriate range, the thickness of the intermediate layer has little effect on the change of the square resistance, that is, it has little effect on the conductivity of the composite current collector. This shows that if the thickness of the intermediate layer is well controlled, the alternating stacking structure formed by the metal layer and the intermediate layer will not significantly affect the conductivity of the composite current collector. The thicker the intermediate layer, the better the safety performance of the battery based on the prepared composite current collector. This is because the thicker the intermediate layer is within the appropriate range, the better the effect of inhibiting the continuous growth of the metal layer grains, and the more effectively it can block the connection between different metal layers. When the intermediate layer is too thin, it cannot effectively inhibit the continuous growth of the metal layer grains, resulting in partial penetration of the grains of the adjacent metal layers, causing the safety performance of the battery to deteriorate sharply.

[0209] From the test results of Examples 1, 26-28 and 30, it can be seen that as the bonding force between the conductive layer and the base film increases, the safety performance of the battery based on the prepared composite current collector first increases and then decreases. This is because if the bonding force is too small, the conductive layer is prone to excessive relative movement with the polymer film during the battery puncture process, which is not conducive to providing sufficient force along the surface of the conductive layer, inhibiting the large-scale expansion and spread of cracks in the conductive layer, and weakening the safety performance of the battery; if the bonding force is too large, it is difficult for local micro-deformation to occur, which is not conducive to the large-scale expansion and spread of cracks in the conductive layer, affecting the improvement of the safety performance of the battery; further, when no bottom layer is set in the composite current collector, it is not conducive to a significant improvement in the safety performance of the battery.

[0210] From the data results of Example 1 and Comparative Example 1, it can be seen that the composite current collector structure provided by the present invention and the structure in the functional layer must cooperate with each other to ultimately achieve the separation of the conductive layer and the steel needle during the acupuncture process, avoid the positive and negative current collectors from being turned on to form a closed loop and the resulting thermal runaway of the battery, thereby greatly improving the safety performance of the battery.

[0211] In summary, the composite current collector structure provided by the present invention, through the coordinated cooperation of various structural layers in the functional layer, can achieve the generation of microcracks in the conductive layer during the needle puncture process, and quickly spread to cause large-area fractures, thereby achieving separation of the conductive layer from the steel needle, avoiding the formation of a closed loop by the positive and negative current collectors and the resulting thermal runaway of the battery, thereby improving the safety performance of the battery and promoting the promotion and application of the composite current collector.

[0212] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A composite current collector, characterized in that: The composite current collector includes a conductive layer. Microcracks will be generated in the conductive layer during the needle puncture process. The microcracks will spread and cause large-area fractures, thereby separating the conductive layer from the steel needle.

2. The composite current collector according to claim 1, characterized in that: The composite current collector comprises a base film and a functional layer located on at least one side of the base film; the functional layer comprises a conductive layer; and the conductive layer comprises metal layers and intermediate layers which are alternately stacked.

3. The composite current collector according to claim 2, characterized in that: The thickness of the base film is 1 to 10 μm; Preferably, the material of the base film includes any one of polyethylene terephthalate, polypropylene, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, polystyrene or polyimide, or a combination of at least two thereof.

4. The composite current collector according to claim 2 or 3, characterized in that: A primer layer is also provided between the base film and the conductive layer; Preferably, the bonding force between the primer layer and the conductive layer is 100 to 900 N / m; Preferably, the material of the base layer includes any one of aluminum oxide, silicon oxide, titanium oxide, nickel, chromium, titanium, nickel-chromium alloy, nickel-chromium-copper alloy, silicon-aluminum alloy, polyacrylic acid, polyacrylate, polyacrylamide or polyurethane, or a combination of at least two thereof.

5. The composite current collector according to any one of claims 2 to 4, characterized in that: The thickness of the conductive layer is 500 to 2000 nm, preferably 800 to 1200 nm; Preferably, the thickness d1 of the metal layer satisfies: 20 <d1≤200nm; Preferably, the thickness d2 of the intermediate layer satisfies: 1nm≤d2≤10nm; Preferably, the thickness of the intermediate layer d2 is less than or equal to one tenth of the thickness of the metal layer d1; Preferably, the number of metal layers in the conductive layer is n, the number of intermediate layers is n-1, and n satisfies: 5≤n≤40; Preferably, the average grain size of the metal in the metal layer is ≤200 nm, preferably 10-100 nm.

6. The composite current collector according to any one of claims 2 to 5, characterized in that: The metal in the metal layer includes any one of aluminum, copper, gold, silver, nickel or zinc and alloys thereof, or a combination of at least two thereof; Preferably, the material of the intermediate layer includes any one or a combination of at least two of alloy, nitride, carbide, sulfide, fluoride, silicide or phosphide, preferably any one or a combination of at least two of carbide, silicide or fluoride; Preferably, the alloy in the intermediate layer includes any one of nickel-chromium alloy, nickel-chromium-copper alloy, nickel-chromium-silicon alloy, nickel-chromium-cobalt alloy, silicon-aluminum alloy, aluminum-silicon-copper alloy, copper-nickel alloy, copper-nickel-titanium alloy, copper-gallium alloy, copper-indium alloy, copper-indium-gallium alloy, aluminum-tin-copper alloy, aluminum-chromium alloy, tungsten-titanium alloy, molybdenum-copper alloy, molybdenum-niobium alloy, molybdenum-tantalum alloy, molybdenum-zirconium-titanium alloy or molybdenum-lanthanum alloy, or a combination of at least two thereof; Preferably, the nitride comprises any one of aluminum nitride, boron nitride, chromium nitride, titanium nitride, silicon nitride, niobium nitride, zirconium nitride, hafnium nitride, tantalum nitride, vanadium nitride or aluminum titanium nitride, or a combination of at least two thereof; Preferably, the carbide comprises any one of aluminum carbide, boron carbide, chromium carbide, nickel carbide, tungsten carbide, titanium carbide, hafnium carbide, zirconium carbide, tantalum carbide, lanthanum carbide, molybdenum carbide, niobium carbide, silicon carbide, titanium carbide or vanadium carbide, or a combination of at least two thereof; Preferably, the sulfide includes any one of copper sulfide, tin sulfide, zinc sulfide, tungsten sulfide, molybdenum sulfide, iron sulfide, antimony sulfide, chromium sulfide, nickel sulfide, titanium sulfide, aluminum copper sulfide or iron copper sulfide, or a combination of at least two thereof; Preferably, the fluoride comprises any one of iridium fluoride, magnesium fluoride, calcium fluoride, lithium fluoride, aluminum fluoride, barium fluoride, samarium fluoride, cerium fluoride, yttrium fluoride or scandium fluoride, or a combination of at least two thereof; Preferably, the silicide includes any one of cobalt silicide, chromium silicide, nickel silicide, titanium silicide, hafnium silicide, molybdenum silicide, niobium silicide, tantalum silicide, vanadium silicide, tungsten silicide or zirconium silicide, or a combination of at least two thereof; Preferably, the phosphide is any one of aluminum phosphide, boron phosphide, copper phosphide, nickel phosphide, silicon phosphide, tungsten phosphide, gallium phosphide, germanium phosphide, indium phosphide, molybdenum phosphide, niobium phosphide or tantalum phosphide, or a combination of at least two thereof.

7. The composite current collector according to any one of claims 2 to 6, characterized in that: A protective layer is also provided on the surface of the conductive layer away from the base film; Preferably, the thickness of the protective layer is 10 to 100 nm, preferably 20 to 80 nm; Preferably, the material of the protective layer includes any one of nickel, chromium, nickel-based alloy, copper-based alloy, copper oxide, aluminum oxide, nickel oxide, chromium oxide, cobalt oxide, copper chromium oxide, graphite, carbon black, carbon nano-quantum dots, carbon nanotubes, carbon nanofibers, graphene or graphene oxide, or a combination of at least two of them.

8. A method for preparing a composite current collector according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: A conductive layer is composited on the surface of at least one side of the base film; wherein the conductive layer comprises metal layers and intermediate layers stacked alternately.

9. The method for preparing a composite current collector according to claim 8, characterized in that: A primer layer is also provided between the base film and the conductive layer; Preferably, the composite method of the primer layer includes magnetron sputtering and / or coating; Preferably, the composite preparation method of the metal layer includes evaporation and / or magnetron sputtering; Preferably, the preparation method of the intermediate layer comprises physical vapor deposition; Preferably, after the conductive layer is obtained by compounding, a protective layer is also provided on the surface of the conductive layer away from the base film; Preferably, the composite preparation method of the protective layer includes any one of physical vapor deposition, chemical vapor deposition, in-situ forming or coating, or a combination of at least two of them.

10. A battery, characterized in that: The battery comprises the composite current collector according to any one of claims 1 to 7 or the composite current collector prepared by the method for preparing the composite current collector according to any one of claims 8 to 9; Preferably, the composite current collector is used in an electrode plate of the battery.

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