Composite current collector and its manufacturing method, as well as lithium battery and power consumption device

Abstract

The present application relates to a composite current collector (10). [Solution] The composite current collector (10) includes: a base layer (1) having a first surface (11) and a second surface (12) arranged back to back along the thickness direction, the base layer (1) being made of a polymer material; a first modified layer (3) arranged on the first surface (11) of the base layer (1), the first modified layer (3) being made of one or more of silicon carbide oxide, titanium carbide oxide, and aluminum carbide oxide nanomaterials; and a first metal layer (2) arranged on the surface of the first modified layer (3) facing away from the base layer (1).

Description

[Technical Field]

[0001] The present application relates to the technical field of lithium batteries, and more particularly to a composite current collector and its manufacturing method, as well as to lithium batteries and power consuming devices. [Background technology]

[0002] At present, lithium batteries have been developed in several aspects, such as higher energy density, higher volume utilization rate and higher safety.

[0003] Compared to conventional pure metal current collectors, the polymer film in the composite current collector has the advantages of high tensile strength, softness, a thin plating layer, light weight, and good internal insulation. Furthermore, the composite current collector is less likely to develop burrs, and even if burrs do develop, they are soft, have a thin plating layer, and are less likely to penetrate the separator, effectively preventing short circuits within the battery and improving battery safety. On the other hand, for a given thickness, the composite current collector has a higher energy density per weight. On the other hand, the ability to reduce the thickness of the composite current collector allows for a higher volumetric energy density.

[0004] However, due to differences in the surface structure and chemical environment of the polymer film and metal layer currently used in composite current collectors, the adhesion between the two is weak after they are combined, and the polymer film and metal layer of the composite current collector are prone to separation during use, which affects the normal use of the composite current collector.

[0005] Therefore, it is necessary to develop a composite current collector that can effectively improve the adhesive performance between the polymer film and the metal layer. Summary of the Invention [Problem to be solved by the invention]

[0006] According to various embodiments, the present application provides a composite current collector and a method for manufacturing the same, as well as a lithium battery, a power consuming device. [Means for solving the problem]

[0007] As a first aspect of the present application, a base layer including a first surface and a second surface disposed back to back along a thickness direction, the base layer being made of a polymer material; a first modified layer disposed on a first surface of the base layer, the first modified layer being made of one or more of silicon oxycarbide, titanium oxycarbide, and aluminum oxycarbide nanomaterials; a first metal layer disposed on a surface of the first modified layer remote from the base layer.

[0008] In one possible embodiment of the first aspect, the lattice structure of the crystals at the surface of the first modified layer close to the first metal layer is doped with metal atoms contained in the first metal layer.

[0009] In one possible embodiment of the first aspect, atoms at the surface of the first modified layer close to the basal layer are covalently bonded to the basal layer.

[0010] In one possible embodiment of the first aspect, the molar content of oxygen atoms at the surface of the first modified layer away from the base layer is about 10% to 50%.

[0011] In one possible embodiment of the first aspect, the average size of the crystal grains on the surface of the first modified layer away from the base layer is about 50 to 88 nm.

[0012] In one possible embodiment of the first aspect, the surface tension of the surface of the first modified layer away from the base layer is about 42 to 57 mN / m.

[0013] In one possible embodiment of the first aspect, the surface roughness of the surface of the first modified layer away from the base layer is about 75 to 125 nm.

[0014] In one possible embodiment of the first aspect, the thickness of the first modified layer is about 100 to 200 nm.

[0015] In one possible embodiment of the first aspect, the thickness of the basal layer is about 2 to 20 μm.

[0016] In one possible implementation of the first aspect, the polymeric material comprises one or more of polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyimide, ethylene propylene copolymer, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene ether, polystyrene, and polyamide.

[0017] In one possible implementation of the first aspect, the device further comprises a second metal layer and a second modification layer; The second modified layer is provided on a second surface of the base layer, and the second metal layer is provided on a surface of the second modified layer away from the base layer, and the material and / or surface structure of the second modified layer are the same as those of the first modified layer.

[0018] In one possible embodiment of the first aspect, the device further comprises a first protective layer and / or a second protective layer; The first protective layer was provided on the surface of the first metal layer remote from the base layer, and the second protective layer was provided on the surface of the second metal layer remote from the base layer.

[0019] In one possible embodiment of the first aspect, the thickness of the first protective layer is less than 1 / 10 of the thickness of the first metal layer, and the thickness of the second protective layer is less than 1 / 10 of the thickness of the second metal layer.

[0020] In one possible embodiment of the first aspect, the thicknesses of the first and second protective layers may be the same or different and are each independently about 10 to 150 nm.

[0021] In one possible embodiment of the first aspect, the thickness of the first metal layer is about 500 to 2000 nm.

[0022] In a second aspect of the present application, there is provided a lithium battery comprising the composite current collector according to the first aspect.

[0023] In a third aspect of the present application, there is provided a power consuming device including the lithium battery according to the second aspect.

[0024] As a fourth aspect of the present application, providing a base layer, the material of which comprises a polymeric material; forming a first modified layer on a first surface along the thickness direction of the base layer, the first modified layer comprising one or more of silicon oxycarbide, titanium oxycarbide, and aluminum oxycarbide nanomaterials; and forming a first metal layer on a surface of the first modified layer remote from the base layer.

[0025] In one possible implementation of the fourth aspect, a first modified layer is formed on a first surface along the thickness direction of the base layer by plasma-assisted chemical vapor deposition.

[0026] In one possible embodiment of the fourth aspect, the RF generator used in the plasma-assisted chemical vapor deposition has a frequency of about 10-15 MHz and a power of about 100-300 W.

[0027] In one possible implementation of the fourth aspect, the reactive gas used in the plasma-assisted chemical vapor deposition process comprises an elemental oxygen gas source, an elemental carbon gas source, and an elemental X gas source, where X comprises one or more of silicon, titanium, and aluminum, and the elemental carbon gas source is a small alkane, such as methane, ethane, or propane.

[0028] In one possible implementation of the fourth aspect, the reaction process includes introducing a plasma gas source into the plasma-assisted chemical vapor deposition apparatus, followed by introducing a reaction gas into the plasma-assisted chemical vapor deposition apparatus; Here, the pressure inside the plasma-assisted chemical vapor deposition apparatus is about 10 to 30 mTorr depending on the amount of plasma gas source introduced, and the pressure inside the plasma-assisted chemical vapor deposition apparatus is about 35 to 50 mTorr depending on the amount of reactive gas introduced, and the flow rate ratios of the oxygen element gas source, carbon element gas source, and X element gas source satisfy the following: the ratio of the total molar amount of oxygen and carbon element contained in the oxygen element gas source and carbon element gas source to the total molar amount of X element is about 2:1, and the molar ratio of the oxygen element to the carbon element is about 3:17 to 3:1.

[0029] In one possible embodiment of the fourth aspect, the reaction time is about 2 to 20 minutes. [Brief explanation of the drawings]

[0030] In order to more clearly describe the technical solutions in the embodiments of the present application or the prior art, the following will briefly describe the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only embodiments of the present application, and those skilled in the art can obtain other drawings based on the disclosed drawings without paying creative labor.

[0031] [Figure 1] FIG. 2 is a schematic cross-sectional view of a composite current collector according to an example of the present application. [Figure 2] 1 shows cross-sectional infrared spectra of the polymer film and modified layer of Example 1 and Comparative Example 1 according to the present invention. [Figure 3] 1 is a flowchart of a method for manufacturing a composite current collector according to an embodiment of the present application. [Figure 4] 1 shows XPS spectra of cross sections of polymer films of Example 1 and Comparative Example 1 according to the present invention. [Figure 5] FIG. 2 is an EDS test diagram of a cross section of a composite current collector of Example 1 according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application, and it should be apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments, and all other embodiments obtained by those skilled in the art based on the embodiments of the present application without paying creative labor fall within the scope of protection of the present application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. The terms used in this specification are only for describing specific examples and are not intended to limit the scope of the present application. The term "and / or" used herein includes any and all combinations of one or more associated items.

[0034] In view of the above technical problems, some embodiments of the present application provide a composite current collector 10, as shown in FIG. 1, including a base layer 1, a first metal layer 2, and a first modified layer 3. Here, the base layer 1 includes a first surface 11 and a second surface 12 arranged back to back along its thickness direction, and the material of the base layer 1 includes a polymer material. The first metal layer 2 is arranged on the first surface 11 of the base layer 1. The first modified layer 3 is arranged on the first surface of the base layer 1, and the material of the first modified layer 3 includes one or more of silicon oxycarbide, titanium oxycarbide, and aluminum oxycarbide nanomaterials. The first metal layer 2 is arranged on the surface of the first modified layer 3 away from the base layer 1.

[0035] In some embodiments, as shown in FIG. 1 , the composite current collector 10 further includes a second metal layer 4 and a second modified layer 5. The second modified layer 5 is disposed on the second surface 12 of the base layer 1, and the second metal layer 4 is disposed on the surface of the second modified layer 5 away from the base layer 1. The material and / or surface structure of the second modified layer 5 are the same as those of the first modified layer 3. In this manner, the material and / or surface structure of the first modified layer 3 can be similar to those of the first modified layer 3. For example, in some embodiments, the materials of the first modified layer 3 and the second modified layer 5 both include one or more of silicon carbide oxide, titanium carbide oxide, and aluminum carbide oxide nanomaterials, and the average grain size and surface roughness of the surfaces of the first modified layer 3 and the second modified layer 5 away from the base layer 1 are the same. The first modified layer 3 and the second modified layer 5 can be manufactured under similar process conditions. In the following examples, the present invention will be described in detail using the first metal layer 2 and the first modified layer 3 as examples, and the description of the second metal layer 4 can refer to the description of the first metal layer 2 below.

[0036] Here, the silicon carbide oxide nanomaterial, titanium carbide oxide nanomaterial, and aluminum carbide oxide nanomaterial all refer to silicon carbide oxide, titanium carbide oxide, and aluminum carbide oxide compounds with sizes on the nanometer order. In one embodiment, the first modified layer 3 containing the silicon carbide oxide nanomaterial, titanium carbide oxide nanomaterial, and aluminum carbide oxide nanomaterial can bond well with polymer materials because atoms (e.g., oxygen atoms) in the first modified layer 3 can form covalent bonds with the polymer materials, thereby improving the bonding strength between the first modified layer 3 and the base layer 1. In another embodiment, the first modified layer 3 may be a nanofilm, and the surface away from the base layer 1 is composed of nanoparticles (or crystal grains) and has a certain roughness. The surface roughness of the first modified layer 3 can be adjusted by adjusting the size of the nanoparticles, thereby adjusting the bonding strength between the first modified layer 3 and the first metal layer 2. In a further embodiment, when the lattice structure of the crystals on the surface of the first modified layer 3 away from the base layer 1 is similar to the lattice structure of the metal of the first metal layer 2, for example, when both the lattice structure of silicon carbide oxide and the lattice structure of the metal are face-centered cubic lattice structures, it is advantageous for the metal lattice of the first metal layer 2 to be embedded within the lattice on the surface of the first modified layer 3 away from the base layer 1, thereby further improving the bonding strength between the first modified layer 3 and the first metal layer and further improving the adhesive ability between the first metal layer 2 and the base layer 1. In yet another embodiment, for silicon carbide oxide nanomaterials, titanium carbide oxide nanomaterials, and aluminum carbide oxide nanomaterials, by controlling the number of oxygen atoms on the surface of the first modified layer 3 away from the base layer 1, the surface tension of the surface of the first modified layer 3 away from the base layer 1 can be adjusted, and an interaction can be generated between the metal atoms and the oxygen atoms on the surface of the first modified layer 3, for example, to form a metal-O bond, thereby improving the adhesive ability between the first modified layer 3 and the first metal layer 2, and further improving the adhesive ability between the first metal layer 2 and the base layer 1, and ultimately improving the bonding strength between the first metal layer 2 and the base layer 1.

[0037] In summary, the first modified layer 3 on the first surface of the base layer 1 is made of one or more of silicon carbide oxide, titanium carbide oxide, and aluminum carbide oxide nanomaterials. Therefore, unlike the related art problem of separation occurring easily between the base layer 1 and the first metal layer 2 due to differences in the surface structure and chemical environment between them, the atoms in the first modified layer 3 can form covalent bonds with the polymer material in the base layer 1, for example, the silicon carbide oxide nanomaterial can form CO-Si bonds with the polymer material, thereby improving the bonding strength between the first modified layer 3 and the base layer 1; and the surface of the first modified layer 3 facing away from the base layer 1 can be physically and / or chemically connected to the first metal layer 2, thereby improving the bonding strength between the first metal layer 2 and the base layer 1. This solves the problem in the related art of separation occurring easily between the base layer 1 and the first metal layer 2, which is detrimental to the normal use of the composite current collector.

[0038] Furthermore, by using one or more of nanomaterials selected from silicon carbide oxide, titanium carbide oxide, and aluminum carbide oxide as the first modified layer 3, the first modified layer 3 has electrical conductivity, and when the first metal layer 2 is formed on its surface, static electricity is generated on the surface of the first modified layer 3, which prevents the formation of hole defects in the composite current collector (e.g., the first metal layer, the first modified layer, and the base layer), thereby improving the yield rate of the product. Furthermore, the reduction in hole defects further improves the density of the first metal layer 2 and further improves the bonding strength between the first metal layer 2 and the first modified layer 3.

[0039] In some embodiments, the lattice structure of the crystals at the surface of the first modified layer 3 close to the first metal layer 2 is doped with metal atoms contained in the first metal layer 2 .

[0040] In these embodiments, the material of the first modified layer 3 may include a silicon carbide nanomaterial, and the lattice structure of the silicon carbide nanomaterial may be a face-centered cubic lattice structure. The lattice structures of metals such as aluminum and copper used in the first metal layer 2 also all belong to a face-centered cubic structure. Therefore, interdigitation easily occurs between the lattice structure of the crystals on the surface of the first modified layer 3 away from the base layer 1 and the lattice structure of the first metal layer 2. Therefore, the lattice structure of the crystals on the surface of the first modified layer 3 close to the first metal layer 2 is doped with metal atoms contained in the first metal layer 2. The above characteristics are identified by performing a line scan of the metal elements on the cross sections of the first modified layer 3 and the first metal layer 2 using an EDS (Energy Dispersive Spectrometer).

[0041] In some embodiments, the silicon oxide carbide nanomaterial may be SiOxCy (x+y=2, 3:17≦x:y≦3:1).

[0042] In some embodiments, a metal-oxygen chemical bond is further formed between the first metal layer 2 and the first modified layer 3. This can further improve the bond strength between the first metal layer 2 and the first modified layer 3. This characteristic can be identified and obtained by XPS (X-ray photoelectron spectroscopy).

[0043] In some embodiments, the molar content of oxygen atoms at the surface of the first modified layer 3 away from the base layer 1 is about 10% to 50%. The molar content of oxygen atoms is also the percentage of the number of oxygen atoms relative to the total number of atoms.

[0044] In these examples, by controlling the molar content of oxygen atoms within the above range, on the one hand, an appropriate surface tension can be imparted to the surface of the first modified layer 3 away from the base layer 1, and on the other hand, the oxygen atoms and the metal atoms contained in the first metal layer 2 form a certain number of metal-oxygen bonds, thereby maximizing the strength of the bond between the first metal layer 2 and the first modified layer 3.

[0045] It should be noted that the molar content of oxygen atoms can be determined using X-ray photoelectron spectroscopy (XPS). During measurement, X-rays are excited at the surface of the first modified layer 3, and the kinetic energy of the electrons emitted within a 30 nm thickness range on the surface of the first modified layer 3 is measured to obtain an XPS spectrum.

[0046] In some embodiments, atoms at the surface of the first modified layer 3 close to the base layer 1 are covalently bonded to the base layer 1 .

[0047] In these embodiments, the bonding strength between the first modified layer 3 and the base layer 1 can be improved, and the bonding strength between the first metal layer 2 and the base layer 1 can be improved.

[0048] This characteristic is obtained by performing an infrared spectroscopic characterization on a cross section of the base layer 1 after modification (for example, the first modified layer 3 and the base layer 1).

[0049] For example, the material of the base layer 1 is a PP (Polypropylene) film, and the first modified layer 3 and the PP film are bonded by a CO—Si bond, to obtain the infrared spectrum shown in FIG.

[0050] The above describes the case where the surface of the first modified layer 3 remote from the base layer 1 and the first metal layer 2 are bonded by chemical bonding, but those skilled in the art should understand that the strength of the bond between the surface of the first modified layer 3 remote from the base layer 1 and the first metal layer 2 is also related to the physical properties of the surface of the first modified layer 3 remote from the base layer 1, such as surface tension and surface roughness. Based on this, in some embodiments, the surface tension of the surface of the first modified layer 3 remote from the base layer 1 is about 42 to 57 mN / m.

[0051] In these examples, by controlling the surface tension of the surface of the first modified layer 3 away from the base layer 1 to within the range of 42 to 57 mN / m, the bonding strength between the first metal layer 2 and the first modified layer 3 can be improved to the maximum extent.

[0052] In some embodiments, the average size of the crystal grains of the nanomaterial on the surface of the first modified layer 3 away from the base layer 1 is about 50 to 88 nm, and the surface roughness of the surface of the first modified layer 3 away from the base layer 1 is about 75 to 125 nm.

[0053] In these embodiments, the bonding strength between the first modified layer 3 and the first metal layer 2 can be improved to the maximum extent.

[0054] Based on the above, it should be further explained that the role of the first modified layer 3 is to improve the surface structure and properties of the base layer 1, and if the modification is uniform, increasing the thickness of the first modified layer 3 will not further improve the bonding strength between the first modified layer 3 and the first metal layer 2, and will also increase the raw material costs.

[0055] Based on this, in some embodiments, the thickness of the first modified layer 3 is about 100 to 200 nm.

[0056] In these examples, by controlling the thickness of the first modified layer 3 within the above range, the base layer 1 can be regarded as the result of a silicon oxide surface modification treatment of the surface of a polymer film, and the bonding strength between the polymer film and the metal layer can be improved without affecting the flexibility of the base layer 1.

[0057] In some embodiments, the modulus of elasticity of the base layer 1 after modification is less than about 3660 MPa.

[0058] In these embodiments, flexibility of the composite current collector can be maintained to the greatest extent possible.

[0059] In some embodiments, the thickness of the base layer 1 is about 2-20 μm.

[0060] The role of base layer 1 is to promote an improvement in the energy density of the composite current collector. Experiments have shown that, although the thinner the base layer 1, the more the energy density of the composite current collector can be promoted, a thinner base layer 1 is not preferable. This is because base layer 1 also functions as a carrier and is used to support first metal layer 2, first modified layer 3, etc. in the process of manufacturing the composite current collector. Therefore, it is most preferable to control the thickness of base layer 1 within the range of 2 to 20 μm.

[0061] Here, there is no specific limitation on the polymer material selected for the base layer 1. The polymer material may be any material that can promote the improvement of the energy density of the composite current collector and has good flexibility.

[0062] In some embodiments, the polymeric material includes one or more of polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyimide, ethylene propylene copolymer, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene ether, polystyrene, and polyamide.

[0063] Polypropylene (PP) is a semi-crystalline thermoplastic with high impact resistance, strong mechanical properties, and resistance to corrosion from various organic solvents and acids and alkalis. Polyethylene (PE) is a thermoplastic resin produced by polymerizing ethylene. It is odorless, non-toxic, has excellent low-temperature resistance, excellent chemical stability, can withstand corrosion from most acids and alkalis, has low water absorption, and has excellent electrical insulation properties. Polyethylene terephthalate (PET) has excellent physical and mechanical properties over a wide temperature range, can reach temperatures of 120°C for long-term use, has excellent electrical insulation properties, and maintains good electrical performance even at high temperatures and high frequencies. It also has good resistance to peristalsis, fatigue resistance, abrasion resistance, and dimensional stability. Polybutylene terephthalate (PBT) is a translucent or opaque crystalline thermoplastic polyester resin produced by the condensation of 1,4-butylene glycol and terephthalic acid or terephthalic acid esters through a kneading process. It offers excellent molding and processing capabilities, high cost performance, and overall performance. Polyethylene naphthalate (PEN) has a similar chemical structure to PET, but differs in that PEN substitutes benzene rings in the molecular chain with more rigid naphthalene rings. Due to the naphthalene ring structure, PEN offers superior physical and mechanical properties, gas barrier properties, chemical stability, and heat, UV, and radiation resistance compared to PET. Polyimide (PI) is a type of polymer containing imide rings (-CO-NR-CO-) in the main chain and is one of the organic polymer materials with optimal overall performance. Ethylene propylene copolymer (PPE) is a composite material made by mixing PPE material with other thermoplastic materials such as PS (styrene) and PA (polyamide, commonly known as nylon), and after processing and molding, both have good geometric stability, chemical stability, electrical insulation, and a low coefficient of thermal expansion.Polyvinyl chloride (PVC) has good mechanical properties and excellent dielectric properties. Polyvinylidene difluoride (PVDF) has excellent properties such as anti-aging, chemical resistance, weather resistance, and UV radiation resistance. Polytetrafluoroethylene (PTFE) has excellent chemical stability, corrosion resistance, sealing properties, high lubricity, low viscosity, electrical insulation, and good anti-aging properties. Polyphenylene sulfide (PPS) is a new high-performance thermoplastic resin with advantages such as high mechanical strength, high temperature resistance, chemical resistance, flame retardancy, good thermal stability, and excellent electrical properties. Polyphenylene ether (PPO) is transparent, has a low relative density, and has excellent mechanical strength, stress relaxation resistance, resistance to peristalsis, heat resistance, water resistance, water vapor resistance, and dimensional stability. Polystyrene (PS) products have extremely high transparency, with a light transmittance of over 90%, excellent electrical insulation, easy coloring, good processing fluidity, good rigidity, and good chemical corrosion resistance. Polyamide (PA) has excellent overall properties, including mechanical properties, heat resistance, abrasion resistance, chemical resistance, and self-lubrication, as well as a low coefficient of friction, some flame retardancy, and is easy to process. It is suitable for reinforcement modification by filling with glass fiber and other fillers, which can improve its performance and expand its range of applications.

[0064] In some embodiments, the material of the first metal layer 2 and the second metal layer 4 may be any metal having current conducting properties. For example, the material of the first metal layer 2 and the second metal layer 4 may be one or more metals selected from copper, aluminum, nickel, titanium, and silver.

[0065] Among metal materials, copper foil and aluminum foil have the best conductivity and are inexpensive. Furthermore, for wound batteries, the pole pieces used to manufacture the battery must have a certain degree of flexibility to ensure that the pole pieces do not break due to brittleness during winding. Copper foil and aluminum foil are also soft metal materials. Furthermore, copper foil and aluminum foil are relatively stable in air. Aluminum easily reacts chemically with oxygen gas in the air to form a dense aluminum oxide film on the aluminum surface, preventing further reaction of the aluminum. This thin aluminum oxide film provides a certain degree of protection for the aluminum in the electrolyte. Copper is relatively stable in air and rarely undergoes chemical reactions in dry air.

[0066] In lithium batteries, the positive electrode potential is high, and copper foil is easily oxidized under high potential, but aluminum has a high oxidation potential and the aluminum foil has a dense oxide film on its surface, which provides good protection for the internal aluminum. Therefore, in some embodiments, when the composite current collector is a positive electrode current collector, the first metal layer 2 and the second metal layer 4 can both be aluminum or an aluminum alloy, and when the composite current collector is a negative electrode current collector, the first metal layer 2 and the second metal layer 4 can both be copper or a copper alloy.

[0067] In some embodiments, as shown in Figure 1, the composite current collector 10 further includes a first protective layer 6 and / or a second protective layer 7. The first protective layer 6 is provided on the surface of the first metal layer 2 away from the base layer 1, and the second protective layer 7 is provided on the surface of the second metal layer 4 away from the base layer 1.

[0068] In these embodiments, the first protective layer 6 and the second protective layer 7 are provided to protect the first metal layer 2 and the second metal layer 4, and prevent the first metal layer 2 and the second metal layer 4 from being exposed to the outside and being subjected to chemical corrosion or physical damage.

[0069] Here, the materials of the first protective layer 6 and the second protective layer 7 may be the same or different, and the thicknesses may be the same or different, and are not specifically limited here, as long as the first protective layer 6 and the second protective layer 7 can protect the first metal layer 2 and the second metal layer 4.

[0070] In some embodiments, the materials of the first protective layer 6 and the second protective layer 7 are both selected from antioxidant materials.

[0071] The antioxidant material may be a metallic or non-metallic material.

[0072] Examples of the metallic material include materials that are unlikely to undergo oxidation reactions in air, such as nickel, chromium, nickel-based alloys, and copper-based alloys, and examples of the non-metallic material include metal oxide materials and non-metallic elements.

[0073] The metal oxide material may, for example, include one or more of copper oxide, alumina, nickel oxide, chromium oxide, and cobalt oxide, and the non-metal element may, for example, include one or more of graphite, carbon black, acetylene black, ketjen black, carbon nano quantum dots, carbon nanotubes, carbon nanofibers, and graphene.

[0074] In some embodiments, the thickness of the first protective layer 6 is less than 1 / 10 of the thickness of the first metal layer, and the thickness of the second protective layer 7 is less than 1 / 10 of the thickness of the second metal layer 4.

[0075] In these examples, by making the thickness of the first protective layer 6 less than 1 / 10 of the thickness of the first metal layer and the thickness of the second protective layer 7 less than 1 / 10 of the thickness of the second metal layer 4, it is possible to prevent the problem of the first protective layer 6 and the second protective layer 7 being too thick, which increases the resistivity of the composite current collector and thereby reduces the conductivity of the composite current collector.

[0076] In some embodiments, the thicknesses of the first protective layer 6 and the second protective layer 7 may be the same or different and are each independently about 10 to 150 nm.

[0077] In these examples, by controlling the thickness of the first protective layer 6 and the second protective layer 7 to within a range of 10 to 150 nm, it is possible to reduce the thickness of the first protective layer 6 and the second protective layer 7 to the maximum extent possible while ensuring good protection of the first metal layer 6 and the second metal layer 7, thereby improving the energy density of the composite current collector.

[0078] Preferably, the thickness of each of the first protective layer 6 and the second protective layer 7 may be about 20 to 100 nm.

[0079] In some embodiments, the thickness of the first metal layer 2 may be about 500 to 2000 nm.

[0080] In these examples, by controlling the thickness of the first metal layer 2 within the range of 500 to 2000 nm, the high conductivity performance of the first metal layer 2 can be ensured while preventing the problem of the first metal layer 2 being too thick and wasting material.

[0081] Preferably, the thickness of the first metal layer 2 is about 700 to 1200 nm.

[0082] Some embodiments of the present application provide a lithium battery including the composite current collector described above.

[0083] In some embodiments, the lithium battery may include a positive electrode piece and a negative electrode piece. The positive electrode piece may include a positive electrode current collector and a positive electrode active material, and the negative electrode piece may include a negative electrode current collector and a negative electrode active material.

[0084] In some embodiments, the positive electrode current collector and / or the negative electrode current collector may be a composite current collector as described above.

[0085] When the positive electrode current collector is the above-mentioned composite current collector, the first and second metal layers included in the composite current collector may both be aluminum foil, and in this case, the lithium battery further includes a positive electrode active material formed on at least one surface of the composite current collector (for example, two back-to-back surfaces of the composite current collector along its thickness direction).When the negative electrode current collector is the above-mentioned composite current collector, the first and second metal layers included in the composite current collector may both be copper foil, and in this case, the lithium battery further includes a negative electrode active material formed on at least one surface of the composite current collector.

[0086] Here, taking the lithium battery as an example of a lithium ion battery, the positive electrode active material may be a lithium alloy metal oxide material, and the negative electrode active material may be a carbon material, a silicon-based material, a titanium oxide material, a tin-based composite material, etc. Unlike a lithium ion battery, when the lithium battery is a lithium metal battery, the negative electrode active material may be metallic lithium or its alloy metal.

[0087] Of course, in some embodiments, when the lithium battery is a lithium ion battery, the positive electrode active material may be a sodium alloy metal oxide material, and in this case, the lithium ion battery may be referred to as a sodium ion battery. When the lithium battery is a lithium metal battery, the negative electrode active material may be metallic sodium or its alloy metal, and in this case, the lithium metal battery may be referred to as a sodium metal battery. In other embodiments, when the lithium battery is a lithium metal battery, the negative electrode active material may be prepared as a slurry and applied to the negative electrode current collector, and a negative electrode material layer (e.g., a lithium metal layer) may be formed on the negative electrode current collector by electroplating.

[0088] Some embodiments of the present application provide a power consuming device that includes the lithium battery described above.

[0089] In some embodiments, the power consuming device may illustratively be an electric vehicle, a mobile phone, a tablet computer, a laptop, or a digital camera.

[0090] Some embodiments of the present application provide a method for manufacturing a composite current collector, as shown in FIG. 3, including:

[0091] S31: Provide a base layer 1, the material of which comprises a polymeric material.

[0092] The base layer 1 may be commercially obtained or manufactured.

[0093] In some embodiments, the base layer 1 can be manufactured using polymeric materials through melt, extrusion and stretch manufacturing processes.

[0094] Here, the stretching may be uniaxial stretching or biaxial stretching.

[0095] S32: A first modified layer 3 is formed on a first surface along the thickness direction of the base layer 1. The material of the first modified layer 3 includes one or more of a silicon oxide nanomaterial and a titanium oxide nanomaterial.

[0096] Here, a first modified layer 3 can be formed on a first surface 11 of the base layer 1 along its thickness direction using plasma-assisted chemical vapor deposition.

[0097] Plasma is the fourth type of state in which matter exists; it is an unbound macroscopic system of equal amounts of free electrons and charged ions.

[0098] Chemical vapor deposition (CVD) is a process that uses gaseous materials to undergo chemical reactions on solid surfaces to produce solid deposits.

[0099] Plasma can be generated by electrical breakdown, RF discharge, microwave excitation, shock waves, high-energy particle streams, high-temperature heating, and other methods.

[0100] Plasma-assisted chemical vapor deposition refers to a solid-state growth method that uses plasma generated by glow discharge in a low-pressure chemical vapor deposition process to control the reaction pressure, airflow rate, material temperature of the substrate (here, the base layer), growth time, etc. during the growth process, thereby controlling the nanomaterial nucleation growth process and crystallization process of the first modified layer 3.

[0101] In the plasma-assisted chemical vapor deposition process, the micro-process is as follows.

[0102] Gas molecules collide with electrons in the plasma, generating active radicals and ions. The active radicals may diffuse directly to the base layer 1, or they may interact with other gas molecules or active radicals to form chemical groups necessary for growth. The chemical groups necessary for growth diffuse to the surface of the base layer 1, and gas molecules may diffuse directly to the vicinity of the base layer 1 without undergoing the activation process described above. The various chemical groups that reach the surface of the base layer initiate various growth reactions and release reaction products. The reaction products are expelled outside the system along with unreacted gas molecules.

[0103] In some embodiments, the reactive gas used in the plasma-assisted chemical vapor deposition may include an oxygen elemental gas source, a carbon elemental gas source, and an X elemental gas source, where X includes one or more of silicon, titanium, and aluminum. The carbon elemental gas source may illustratively be a short-chain alkane such as methane, ethane, or propane.

[0104] Here, an inert gas is used as the plasma gas source, and the gas molecules are used as the reactive gas. The gas molecules are collided with electrons in the plasma to generate active groups containing one or more of silicon, titanium, and aluminum atoms and oxygen atoms. When the active groups containing one or more of silicon, titanium, and aluminum atoms and oxygen atoms diffuse into the base layer 1, a nanomaterial film can be formed on the base layer 1.

[0105] In this process, by controlling the gas flow rates of the plasma gas source, oxygen gas and reactive gas, the nucleation process of the nanomaterial in the first modified layer 3 can be controlled, thereby controlling the crystal grain size, molar content of oxygen atoms (hereinafter referred to as oxygen atom content), etc. of the nanomaterial in the first modified layer 3, and further controlling the crystal grain size, oxygen atom content, surface roughness and surface tension, etc. of the surface away from the base layer of the first modified layer 3, thereby preparing for improved adhesion ability between the subsequent first modified layer 3 and the first metal layer 2.

[0106] In some embodiments, before the reaction begins, the pressure inside the plasma-assisted chemical vapor deposition apparatus is first reduced to about 10 mTorr or less by evacuation. During the reaction process, a plasma gas source is first introduced into the plasma-assisted chemical vapor deposition apparatus, and then a reactant gas is introduced into the plasma-assisted chemical vapor deposition apparatus. Here, the pressure inside the plasma-assisted chemical vapor deposition apparatus is about 10 to 30 mTorr depending on the amount of the plasma gas source introduced, the pressure inside the plasma-assisted chemical vapor deposition apparatus is about 35 to 50 mTorr depending on the total amount of the reactant gas introduced, and the flow rates of the oxygen gas source, carbon gas source, and X element gas source satisfy the following: the ratio of the total molar amount of oxygen and carbon contained in the oxygen gas source and carbon gas source to the total molar amount of X is about 2:1, and the molar ratio of the oxygen element to the carbon element is about 3:17 to 3:1.

[0107] In these embodiments, a plasma gas source is first introduced, and the plasma gas source generates plasma under the action of glow power generation. Then, a reactive gas is introduced and the plasma is used to activate the reactive gas, causing the two to react with each other, thereby precipitating one or more of silicon atoms, titanium atoms, and aluminum atoms, and oxygen atoms on the surface of the base layer 1, thereby forming a first modified layer 3.

[0108] During this process, the plasma gas source introduction pressure, the reactive gas introduction pressure, and the flow rate ratio of the oxygen gas source, carbon gas source, and X element gas source can be controlled to adjust the surface structure and properties of the first modified layer 3 so that the grain size, surface tension, surface roughness, sheet resistance, and other properties of the surface of the first modified layer 3 away from the base layer 1 can meet application needs. Furthermore, a too high or too low molar content of oxygen atoms is detrimental to the uniform distribution of oxygen atoms on the surface of the first modified layer 3 and to the bonding between the subsequent first metal layer and the first modified layer 3. A too low molar content of carbon atoms is detrimental to improving the surface conductivity of the first modified layer 3 and reducing surface hole defects. A too high molar content of carbon atoms and a too low molar content of oxygen atoms is detrimental to improving the bonding strength between the subsequent first metal layer and the first modified layer 3.

[0109] In some embodiments, the plasma gas source may include one or more of argon gas, helium gas, and neon gas. The silicon gas source may be an alkoxysilane, and the alkoxysilane may be one or more selected from hexamethyldisiloxane, tetraethoxysilane, dimethyldiethoxysilane, ethyltriethoxysilane, and vinyltriethoxysilane.

[0110] The titanium element gas source may be a titanate ester, which may be one or more selected from isopropyl titanate, n-propyl titanate, ethyl titanate, and methyl titanate.

[0111] The aluminum gas source may be an alkyl aluminum, which may be one or more selected from trimethyl aluminum, triethyl aluminum, and triisobutyl aluminum.

[0112] The carbon element gas source is a short-chain alkane, which may be one or more selected from methane, ethane, and propane.

[0113] The elemental oxygen gas source may be oxygen gas.

[0114] In some embodiments, plasma-assisted chemical vapor deposition can be achieved by generating plasma using an RF generator, the frequency of which can be about 10-15 MHz, and the power of which can be about 100-300 W, thereby achieving low-temperature deposition.

[0115] Limiting the frequency and power of the RF generator within the above ranges can improve the deposition yield and the uniformity of the distribution of oxygen atoms in the first modified layer 3. If the power is too small, the growth effect will be poor, and if the power is too large, the distribution of oxygen atoms in the first modified layer will be non-uniform.

[0116] In some embodiments, the reaction time may be about 2 to 20 minutes.

[0117] These examples allow for good control of the thickness and surface properties of the first modified layer 3. If the reaction time is too short, the formation of the first modified layer 3 will be incomplete and the desired effect will not be achieved, while if the reaction time is too long, the thickness of the first modified layer 3 will increase cumulatively, which is unfavorable for controlling raw material costs.

[0118] It should be noted that the plasma-assisted chemical vapor deposition apparatus may be a roll-to-roll type plasma-assisted chemical vapor deposition apparatus. The apparatus is equipped with a take-up roll. In this manner, chemical vapor deposition can be performed on both the front and back sides of the polymer film. That is, a first modified layer 3 is formed on a first surface of the base layer 1, and a second modified layer 5 is formed on a second surface of the base layer 1. The ranges of the parameters of the second modified layer 5 are the same as those of the first modified layer 3. For details, please refer to the descriptions of the parameters above, and a detailed description will not be repeated here.

[0119] S33: A first metal layer 2 is formed on the surface of the first modified layer 3 that is away from the base layer 1.

[0120] The first metal layer 2 can be formed on the surface of the first modified layer 3 away from the base layer 1 by one or more methods such as physical vapor deposition (e.g., resistance heating vacuum deposition, electron beam heating vacuum deposition, laser heating vacuum deposition, magnetron sputtering, etc.), electroplating, chemical plating, etc.

[0121] Similar to the second modified layer 5, the manufacturing method of the second metal layer 4 may be the same as that of the first metal layer 2, and will not be repeated here.

[0122] S34: A first protective layer 6 is formed on the surface of the first metal layer 2 that is away from the base layer 1.

[0123] The first protective layer 6 can be formed on the surface of the first metal layer 2 remote from the base layer 1 by one or more of the following methods: physical vapor deposition, chemical vapor deposition, in-situ casting and coating.

[0124] Here, the vapor deposition method may include one or more of vacuum evaporation and magnetron sputtering. The chemical vapor deposition may include one or more of atmospheric pressure chemical vapor deposition and plasma-assisted chemical vapor deposition. The in-situ molding may be a method of in-situ forming a metal oxide (e.g., one or more of the above-mentioned copper oxide, aluminum oxide, nickel oxide, chromium oxide, and cobalt oxide) on the surface of the first metal layer 2. This allows the first protective layer 6 containing the metal oxide to be obtained. The coating method may include one or more of die coating, knife coating, and squeeze coating.

[0125] In some embodiments, the method further comprises forming a second protective layer 7 on a surface of the second metal layer 4 remote from the base layer 1, as shown in FIG.

[0126] Here, the method for manufacturing the second protective layer 7 may be the same as the method for manufacturing the first protective layer 6, and therefore will not be described again here.

[0127] Specific embodiments of the present invention have been described above. In order to objectively explain the technical effects of the present invention, the following examples and comparative examples will be used.

[0128] In the following examples and comparative examples, all raw materials can be purchased commercially, and in order to maintain the reliability of the tests, the raw materials used in the following examples and comparative examples all have the same physical and chemical parameters or undergo the same processing.

[0129] Example 1 Preparation of surface-modified polymer film (i.e., forming a first modified layer and a second modified layer on the upper and lower surfaces of the polymer film)

[0130] A commercially available 6 μm-thick biaxially oriented polypropylene (PP) film was placed in a plasma-assisted chemical vapor deposition (PECVD) reactor. The RF generator in the PECVD reactor was set to a frequency of 13.45 MHz and a power of 100 W. A vacuum pump was used to evacuate the chamber until the pressure inside the chamber reached approximately 10 mTorr. The argon gas line control valve was then opened to slowly introduce argon gas into the PECVD reactor, and the argon gas flow rate was adjusted to maintain the chamber pressure at approximately 20 mTorr. The oxygen, ethane, and hexamethyldisiloxane line valves were then opened to slowly introduce oxygen, ethane, and hexamethyldisiloxane. The total flow rate of the oxygen and ethane was adjusted so that the ratio of the total flow rate to the hexamethyldisiloxane was approximately 2:1, and the ratio of the oxygen gas to the ethane was approximately 3:17, maintaining the chamber pressure at approximately 40 mTorr. After about 2 minutes of treatment, the introduction of gas was stopped, the vacuum pump was turned off, and the pressure was released. After the pressure release was completed, the polymer film was taken out to obtain a surface-modified PP film.

[0131] Manufacturing of composite current collectors Preparation of metal layers (preparation of first metal layer and second metal layer): The surface-modified PP film prepared above was placed in a vacuum deposition chamber, and high-purity copper wire (purity greater than 99.99%) in the metal evaporation chamber was melted and evaporated at a high temperature of 1400-2000°C. The evaporated metal atoms were precipitated on the two surfaces of the surface-modified polymer film described above through the cooling system in the vacuum plating chamber, forming a copper metal layer with a thickness of approximately 1 μm.

[0132] Fabrication of protective layer (fabrication of first protective layer and second protective layer): Approximately 1 g of graphene was uniformly dispersed in approximately 999 g of N-methylpyrrolidone (NMP) solution using ultrasonic dispersion to prepare a coating solution with a solid content of approximately 0.1 wt%. The coating solution was then uniformly applied to the surface of the metal layer using a die coating process, the coating thickness was controlled to 80 μm, and the layer was dried at 80°C to produce a protective layer.

[0133] Example 2 The power of the RF generator was about 200 W, but was basically the same as in Example 1.

[0134] Example 3 The power of the RF generator was about 300 W, but was basically the same as in Example 1.

[0135] Example 4 The procedure is basically the same as in Example 1, except that the flow rate ratio of oxygen gas to ethane is about 1:1.

[0136] Example 5 The procedure is basically the same as in Example 1, except that the flow ratio of oxygen gas to ethane is about 3:1.

[0137] Example 6 The procedure was basically the same as in Example 1, except that the denaturation treatment time was about 5 minutes.

[0138] Example 7 The procedure was basically the same as in Example 1, except that the time for the denaturation treatment was about 10 minutes.

[0139] Example 8 The procedure was basically the same as in Example 1, except that the denaturation treatment time was about 15 minutes.

[0140] Example 9 The procedure was basically the same as in Example 1, except that the denaturation treatment time was about 20 minutes.

[0141] Example 10 The procedure is basically the same as in Example 1, except that a PET film is selected as the polymer film.

[0142] Comparative Example 1 The power of the RF generator was about 95 W, but was basically the same as in Example 1.

[0143] Comparative Example 2 The power of the RF generator was about 305 W, but was basically the same as in Example 1.

[0144] Comparative Example 3 The procedure is basically the same as in Example 1, except that the flow ratio of oxygen gas to ethane is about 3:18.

[0145] Comparative Example 4 The procedure is basically the same as in Example 1, except that the flow ratio of oxygen gas to ethane is about 4:1.

[0146] Comparative Example 5 The procedure was basically the same as in Example 1, except that the time for the denaturation treatment was about 1 minute.

[0147] Comparative Example 6 The procedure was basically the same as in Example 1, except that the denaturation treatment time was about 21 minutes.

[0148] Comparative Example 7 The procedure was basically the same as in Example 1, except that the polymer film was not subjected to a surface modification treatment.

[0149] Test evaluation As described above, the presence of a CO-Si covalent bond between the modified layer (i.e., the first and second modified layers) and the polymer film improves the bond strength between the polymer film and the modified layer, while the presence of a metal-O chemical bond between the modified layer and the metal layer, along with parameters such as the surface structure and properties of the modified layer, promotes adhesion between the modified layer and the metal layer. To demonstrate this, infrared spectroscopy scans were performed on cross sections of the polymer film and modified layer in Example 1 and Comparative Example 1, XPS scans were performed on the vicinity of the interface between the modified layer and the metal layer in Example 1 and Comparative Example 1, and EDS line scans were performed on the vicinity of the interface between the modified layer and the metal layer in Example 1. Specific measurement methods and results are as follows:

[0150] 1. Infrared spectroscopic scan measurement: A cross-sectional sample was prepared for the modified polymer film produced in Example 1 using an argon ion polisher (Fischione 1061), and then the cross-sectional sample was placed in a Fourier transform attenuated total reflectance infrared spectrophotometer (Thermo Nicolet 6700) and infrared spectroscopic scan was performed on the cross-section to obtain the infrared spectrum shown in Figure 2. A cross-sectional sample was prepared for the polymer film of Comparative Example 1 in the same manner as in Example 1, and the above procedure was repeated to perform infrared spectroscopic scan, obtaining the infrared spectrum shown in Figure 2.

[0151] As can be seen from Figure 2, compared to the unmodified PP film, the infrared spectrum of the modified PP film shows a peak at 1250 cm -1 , 1199cm -1 , 1077cm -1 , 956cm -1 , 783cm -1 The characteristic absorption peaks at positions such as 1000 and 1000 correspond to the characteristic absorption peaks of the symmetric stretching vibration of C-O-Si, the symmetric stretching vibration of C-Si, the symmetric stretching vibration of Si-O-Si, the symmetric stretching vibration of C-O-Si, the bending stretching vibration of C-O-Si, and the asymmetric stretching vibration of Si-O-Si, respectively. This indicates the formation of a modified layer and the formation of a C-O-Si covalent bond between the modified layer and the PP base film.

[0152] 2. XPS Measurement: The surface of the produced composite current collector was polished using an argon ion polisher (Fischione 1061) to remove the protective layer and the oxidized metal layer, and then a cross-sectional sample was prepared. After sample preparation was completed, the prepared cross-sectional sample was placed in an XPS (PHI Versaprobe 4) and the sample cross-section was scanned to obtain the XPS spectrum shown in Figure 4. The same cross-sectional sample preparation as in Example 1 was performed on the polymer film of Comparative Example 1, and the above procedure was repeated to perform an infrared spectroscopic scan, obtaining the XPS spectrum shown in Figure 4.

[0153] As can be seen from Figure 4, the cross-sectional XPS spectrum of the composite current collector manufactured using modified PP film as the base film shows characteristic peaks of Cu(I) and Cu(II), compared to the composite current collector manufactured using unmodified PP film as the base film, proving the formation of Cu-O chemical bonds between the modified PP film and the metal layer. Here, Cu(I) represents monovalent copper ions, and Cu(II) represents divalent copper ions.

[0154] 3. EDS (Energy Dispersive Spectrometer, Energy Dispersive X-ray Spectroscopy) Measurement: A cross-sectional sample was prepared for the manufactured composite current collector using an argon ion polisher (Fischione 1061). The prepared cross-sectional sample was placed in an EDS (Energy Dispersive X-ray Spectrometer), which is an X-ray energy dispersive spectrometer (Bruker QUANTAX EDS XFlash (registered trademark) 7). X-ray scanning was performed near the interface between the modified layer and the metal layer (extending 30 nm above and below the interface as the origin), and the EDS test diagram shown in Figure 5 was obtained.

[0155] As shown in Figure 5, the coordinate origin is the interface between the modified layer and the metal layer, with negative coordinates indicating the metal layer side and positive coordinates indicating the modified layer side. Metallic Cu was detected from the interface to a depth of 30 nm or more into the modified layer, indicating that copper crystals were embedded in the modified layer. This is because, during the metal layer formation process, the surface temperature of the modified layer was high, causing the crystals in the modified layer to rearrange and migrate. The resulting Cu crystals and the silicon carbide crystals in the modified layer both have face-centered cubic lattice structures, which are similar, resulting in interdigitation between the copper crystals and the silicon carbide crystals.

[0156] As mentioned above, one of the purposes of producing a surface-modified polymer film is to improve the bonding performance between the polymer film and the metal layer, thereby solving the problem of poor adhesion between the base film and the metal layer of a composite current collector fabricated using a polymer film as the base film. The bonding performance between the polymer film and the metal layer depends on the structure and properties of the surface. Here, a silicon oxide surface modification treatment was performed on the polymer film, and the average surface crystal grain size, surface oxygen atom content, surface tension, surface roughness, and adhesive strength between the polymer film and the metal layer of the surface-modified polymer film according to the present application and the unmodified polymer film of the related art were measured to determine the influence of the surface structure and properties of the polymer film on the bonding performance between the polymer film and the metal layer in the examples and comparative examples according to the present application. Another purpose of producing a surface-modified polymer film is to improve the surface conductivity of the produced polymer film and reduce the number of static-caused hole defects during the physical vapor deposition process. Here, the sheet resistance of the surface-modified polymer film produced and the number of holes on the film surface of the produced composite current collector were determined. In order to objectively evaluate the modification effect of the examples of the present application, the present application further specified the thickness of the modified layer (i.e., silicon carbide layer) and specified the elastic modulus of the polymer film formed with modified layers of different thicknesses, thereby objectively evaluating the flexibility of the polymer film after modification. The specific measurement methods and measurement results are as follows:

[0157] 1. Measurement of the average particle size of surface crystal grains: The polymer films produced in Examples 1 to 16 and Comparative Example 1 were placed under a field emission scanning electron microscope to measure the surface morphology, and the average particle size of the surface crystal grains corresponding to Examples 1 to 16 and Comparative Example 1 was analyzed using image processing software. The specific measurement results are shown in Table 1 below.

[0158] 2. Measurement of surface oxygen atom content: X-ray photoelectron spectroscopy (XPS) was used to identify the surface elements of the polymer film, and the relative surface oxygen atom content of the polymer films corresponding to Examples 1 to 16 and Comparative Example 1 was analyzed. The specific measurement results are shown in Table 1 below.

[0159] 3. Surface tension measurement: The measurement was carried out in accordance with Chinese standard GB / T14216-2008, and the specific measurement results are shown in Table 1 below.

[0160] 4. Surface roughness measurement: The measurement was carried out in accordance with Chinese standard GB / T31227-2014, and the specific measurement results are shown in Table 1 below.

[0161] 5. Adhesion strength between polymer film and metal layer: One layer of Permacel P-94 double-sided tape was adhered to 1 mm thick aluminum foil, a composite current collector was adhered on the double-sided tape, and one layer of ethylene acrylic acid copolymer film (DuPont Nurcel 0903, thickness 50 μm) was coated on the composite current collector. The adhesive strength was approximately 1.3 × 105 N / m 2 The sample was then hot-pressed at 120°C for 10 seconds, cooled to room temperature, and cut into 150mm x 15mm pieces. Finally, the ethylene-acrylic acid copolymer film sample was fixed to the upper fixture of a tensile machine, and the remaining part was fixed to the lower fixture. The upper and lower fixtures were then moved at a speed of 100mm / min and through an angle of 180° to peel the polymer film from the metal layer. The tensile force applied during peeling was measured to determine the adhesive strength between the polymer film and the metal layer. The specific measurement results are shown in Table 1 below.

[0162] 6. Modified layer thickness: The modified polymer film sample prepared above was placed in an argon ion polisher (Fischione 1061) and cut using an argon ion beam (1 mm diameter). After cutting was complete, the sample was subjected to a sputtering process to prepare a cross-sectional sample. The prepared cross-sectional sample was placed in a field emission scanning electron microscope (Zeiss Gemini Sigma 300VP SEM) and magnified 50,000 times to observe the cross-sectional morphology of the sample. The thickness of the modified layer on the cross-sectional morphology was marked using the measurement software attached to the electron microscope to obtain the thickness of the modified layer.

[0163] 7. Modified polymer film elastic modulus: Refer to Chinese standard GB / T 1040.3-2006.

[0164] 8. Sheet resistance: The prepared surface-modified polymer film was placed on a sample stage, and the sheet resistance of the sample was measured using a four-point probe sheet resistance meter.

[0165] 9. Pores: The finished composite current collector was placed on a surface quality detection system (WINTRISS charge-coupled device CCD), the surface was scanned, and the optical signal was converted into an electrical signal which was then transmitted to a computer to count the number of pores on the surface of the finished composite aluminum current collector per unit area (per square meter) with a pore size of less than 100 μm (it is generally required that the finished product should not have pores larger than 100 μm).

[0166] [Table 1]

[0167] As can be seen from Table 1, the adhesion strength between the surface-modified polymer film and the metal layer was effectively improved, and hole defects on the surface of the prepared composite current collector were effectively controlled. In particular, when the power of the RF generator was controlled within the range of 100-300 W, the flow ratio of oxygen to ethane was controlled within the range of 3:17-3:1, and the reaction time was 2-20 min, the adhesion strength between the surface-modified polymer film and the metal layer could reach 1.0 N / cm or more, and there were no hole defects on the surface of the prepared composite current collector. This significantly improved the adhesion strength between the polymer film and the metal layer, and significantly reduced the surface defects of the prepared composite current collector.

[0168] Comparing Examples 1-3 with Comparative Examples 1-2, we found that with increasing RF generator power, the average size and surface roughness of the silicon carbide nanocrystal grains on the surface of the modified polymer film gradually increased, while the surface oxygen atom content and surface tension remained unchanged. These changes in surface structure and properties initially increased and then decreased the adhesion between the polymer film and the metal layer. Furthermore, with increasing RF generator power, the growth efficiency improved, gradually increasing the thickness of the modified layer. However, the increased thickness of the modified layer decreased the surface resistance and slightly increased the elastic modulus. As the thickness gradually increased, the elastic modulus remained within an acceptable range, without significantly affecting the flexibility of the composite current collector. This suggests that controlling the RF generator power within the range of 100-300 W resulted in optimal surface structure and properties of the resulting polymer film, and maximized adhesion between the polymer film and the metal layer.

[0169] A comparison of Examples 1, 4, and 5 with Comparative Examples 3 and 4 revealed that as the flow rate ratio of introduced oxygen to ethane increased, the size and surface roughness of the silicon carbide crystal grains on the polymer film surface remained essentially unchanged, while the surface oxygen atom content and surface tension increased. These changes in surface structure and properties tended to increase the adhesion between the polymer film and the metal layer. Furthermore, as the flow rate ratio of introduced oxygen to ethane increased, the thickness of the modified layer remained essentially unchanged. However, as the flow rate ratio of introduced oxygen to ethane increased, the carbon content of the modified layer decreased, resulting in decreased conductivity and increased sheet resistance. When the ratio of the two was too high, the surface sheet resistance was too low, resulting in poor conductivity and the occurrence of hole defects on the surface of the resulting composite current collector film. When the ratio of the two was too low, the surface oxygen content was low, resulting in low surface tension and therefore poor adhesion between the base film and metal layer of the resulting composite current collector. As can be seen, when the flow ratio of oxygen to ethane is within the range of 3:17 to 3:1, the adhesion between the polymer film and the metal layer is improved to the maximum extent, and the film surface of the manufactured composite current collector is free of hole defects, thereby satisfying the requirement for hole defects in battery applications.

[0170] A comparison of Examples 1, 6-9, and Comparative Examples 5-6 revealed that with increasing treatment time, the average size and surface roughness of the silicon carbide nanocrystalline grains on the polymer film surface gradually increased, while the surface oxygen atom content and surface tension remained unchanged. These changes in surface structure and properties led to an initial increase and then a subsequent decrease in the adhesion between the polymer film and the metal layer. Furthermore, with increasing treatment time, the thickness of the modified layer increased, the sheet resistance decreased, and the modulus of elasticity increased slightly. However, these were all within acceptable ranges and did not significantly affect the flexibility of the composite current collector. Consequently, longer treatment times were detrimental to the subsequent improvement of the adhesion between the polymer film and the metal layer. Controlling the treatment time within the range of 2-20 minutes achieved the greatest improvement in the adhesion between the polymer film and the metal layer.

[0171] A comparison between Example 1 and Example 10 revealed that the modification effects of the PP film and the PET film were similar under the same modification conditions.

[0172] A comparison of Examples 1 to 9 with Comparative Example 7 revealed that, compared to an unmodified PP film, the adhesive strength between the base film and the metal layer of the composite current collector manufactured using the modified PP film as the base film was significantly improved, and the hole defects on the surface were significantly reduced.

[0173] In summary, by forming first and second modified layers on the upper and lower surfaces of a polymer film and controlling the process conditions for forming the first and second modified layers, it is possible to tailor the microstructure and properties of the surfaces of the first and second modified layers away from the polymer film. The resulting polymer film can effectively improve the bonding strength between the metal layer and the polymer film when the metal layer is deposited. Tests have shown that the larger the parameters in the process conditions for forming the first and second modified layers, the better, but that the microstructure and properties of the surfaces of the first and second modified layers away from the polymer film are related to each other. This provides a basis for investigating the influence of the surface structure and properties of the polymer film on the bonding strength between the polymer film and the metal layer.

[0174] The technical features of the above-described embodiments can be combined in any manner, and for the sake of brevity, not all possible combinations of the technical features in the above-described embodiments are described, but as long as there is no contradiction in the combination of these technical features, they should be considered within the scope described in this specification.

[0175] The above examples only represent some embodiments of the present application, and although the description is specific and detailed, it should not be understood as limiting the scope of the claims. Those skilled in the art may make minor modifications and improvements without departing from the spirit of the present invention, and all of these fall within the scope of protection of the present invention. Therefore, the scope of protection of the present application is defined by the appended claims.

Claims

1. a base layer including a first surface and a second surface disposed back to back along a thickness direction, the base layer being made of a polymeric material; a first modified layer disposed on a first surface of the base layer, the first modified layer being made of one or more of silicon oxycarbide, titanium oxycarbide, and aluminum oxycarbide nanomaterials; a first metal layer provided on a surface of the first modified layer away from the base layer; Composite current collector.

2. The composite current collector according to claim 1 , wherein a lattice structure of the crystals at a surface of the first modified layer close to the first metal layer is doped with metal atoms contained in the first metal layer.

3. 3. The composite current collector according to claim 1, wherein atoms at a surface of the first modified layer close to the base layer are bonded to the base layer by a covalent bond.

4. The molar content of oxygen atoms at the surface of the first modified layer away from the base layer is about 10% to 50%. The composite current collector according to any one of claims 1 to 3.

5. 5. The composite current collector according to claim 1, wherein the average size of crystal grains on the surface of the first modified layer away from the base layer is about 50 to 88 nm.

6. The surface tension of the first modified layer away from the base layer is about 42 to 57 mN / m. The composite current collector according to any one of claims 1 to 5.

7. the surface roughness of the first modified layer away from the base layer is about 75 to 125 nm; The composite current collector according to any one of claims 1 to 6.

8. The thickness of the first modified layer is about 100 to 200 nm. The composite current collector according to any one of claims 1 to 7.

9. The thickness of the basal layer is about 2 to 20 μm. The composite current collector according to any one of claims 1 to 8.

10. the polymeric material comprises one or more of polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyimide, ethylene propylene copolymer, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene ether, polystyrene, and polyamide; The composite current collector according to any one of claims 1 to 9.

11. further comprising a second metal layer and a second modification layer; the second modified layer is provided on a second surface of the base layer, the second metal layer is provided on a surface of the second modified layer away from the base layer, and the material and / or surface structure of the second modified layer are the same as those of the first modified layer; The composite current collector according to any one of claims 1 to 10.

12. further comprising a first protective layer and / or a second protective layer; the first protective layer is provided on a surface of the first metal layer away from the base layer, and the second protective layer is provided on a surface of the second metal layer away from the base layer; The composite current collector of claim 11.

13. the thickness of the first protective layer is less than 1 / 10 of the thickness of the first metal layer; The thickness of the second protective layer is less than 1 / 10 of the thickness of the second metal layer. The composite current collector of claim 12.

14. the thickness of the first protective layer and the second protective layer may be the same or different, and each independently is about 10 to 150 nm; The composite current collector according to claim 12 or 13.

15. The thickness of the first metal layer is about 500 to 2000 nm. The composite current collector according to any one of claims 1 to 14.

16. A composite current collector comprising the composite current collector according to any one of claims 1 to 15. Lithium battery.

17. 17. A lithium battery comprising the lithium battery of claim 16. Power consumption equipment.

18. providing a base layer, the material of which comprises a polymeric material; forming a first modified layer on a first surface along the thickness direction of the base layer, the first modified layer comprising one or more of silicon oxycarbide, titanium oxycarbide, and aluminum oxycarbide nanomaterials; forming a first metal layer on a surface of the first modified layer away from the base layer; Method for manufacturing a composite current collector.

19. forming the first modified layer on a first surface of the base layer along the thickness direction thereof by plasma-assisted chemical vapor deposition; 20. The method of claim 18.

20. The high frequency generator used in the plasma-assisted chemical vapor deposition method has a frequency of about 10 to 15 MHz and a power of about 100 to 300 W.

20. The method of claim 19.

21. The reactive gas used in the plasma-assisted chemical vapor deposition method includes an oxygen elemental gas source, a carbon elemental gas source, and an X elemental gas source, where X includes one or more of silicon, titanium, and aluminum; 21. The method of claim 19 or 20.

22. During the reaction, a plasma gas source is introduced into the plasma-assisted chemical vapor deposition apparatus, and then a reaction gas is introduced into the plasma-assisted chemical vapor deposition apparatus; wherein the pressure inside the plasma-assisted chemical vapor deposition apparatus is about 10 to 30 mTorr due to the amount of plasma gas source introduced, the pressure inside the plasma-assisted chemical vapor deposition apparatus is about 35 to 50 mTorr due to the amount of reaction gas introduced, and the flow rate ratios of the oxygen element gas source, the carbon element gas source and the X element gas source satisfy the following: the ratio of the total molar amount of oxygen and carbon contained in the oxygen element gas source and the carbon element gas source to the total molar amount of X element is about 2:1, and the molar ratio of the oxygen element to the carbon element is about 3:17 to 3:

1.

22. The method of claim 21.

23. The reaction time is about 2 to 20 minutes.

23. The method of claim 22.

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