Composite current collector for lithium battery, device for preparing composite current collector, and method for preparing composite current collector for lithium battery

Abstract

A composite current collector for a lithium battery, a device for preparing a composite current collector, and a method for preparing a composite current collector for a lithium battery. The composite current collector comprises a base film, an intermediate layer and a metal layer. The intermediate layer comprises composite particles, each composite particle comprising a conductive core and a thermoplastic coating layer, wherein the core is fully or partially wrapped by the coating layer and distributed on the base film, so as to improve the mechanical strength of the composite current collector such that the composite current collector is less prone to thermal shrinkage and deformation. The device comprises a conveying assembly, a spraying apparatus and a coating assembly, wherein the conveying assembly is used for conveying a base film; the spraying apparatus is used for spraying composite particles to form an intermediate layer on the base film; and the coating assembly is used for forming a metal layer on the intermediate layer.

Description

Composite current collector for lithium battery, equipment for preparing composite current collector, and method for preparing composite current collector for lithium battery Technical Field

[0001] The present invention belongs to the field of composite current collectors for lithium batteries, and in particular relates to a composite current collector for lithium batteries, equipment for preparing the composite current collector, and a method for preparing the composite current collector for lithium batteries. Background Art

[0002] With the continuous growth of the new energy vehicle industry, the demand for lithium-ion batteries has also increased rapidly. As one of the indispensable components of lithium-ion batteries, the current collector can not only carry active substances, but also collect and output the current generated by the active substances of the electrodes. The composite current collector is a composite material that uses raw material films such as PET / PP as the base film and undergoes processes such as vacuum coating to deposit metal atoms on both sides to form a three-layer composite structure of "metal-polymer material-metal". The common vacuum preparation methods currently used are basically magnetron sputtering, evaporation coating, or one or a combination of these. After magnetron sputtering forms a nm-level base layer on the surface, vacuum evaporation and other methods are used to thicken the metal layer. In this process, how to ensure good adhesion between the base film and the coating is the key to the subsequent stable operation of the composite current collector.

[0003] Summary of the Invention

[0004] In view of this, the present application proposes a composite current collector for a lithium battery, an apparatus for preparing the composite current collector, and a method for preparing the composite current collector for a lithium battery to solve the above problems.

[0005] According to an embodiment of the present application, a composite current collector for a lithium battery is provided. The composite current collector comprises a base film, an intermediate layer, and a metal layer formed on the intermediate layer. The intermediate layer comprises composite particles. The composite particles comprise a conductive core and a thermoplastic coating. The core is fully or partially encapsulated by the coating and distributed on the base film to enhance the mechanical strength of the composite current collector and prevent it from thermal shrinkage and deformation.

[0006] In certain embodiments, the composite current collector has an elongation at break in a range of 31.2%-48.2%.

[0007] In certain embodiments, the composite current collector has a peel strength in the range of 6.8-9.3 N / cm.

[0008] In certain embodiments, the composite current collector has a tensile strength in the range of 182-233 MPa.

[0009] In certain embodiments, the coating layer includes any one of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polyoxymethylene, polycarbonate, polyphenylene ether, polysulfone, and polyethylene terephthalate, or a mixture thereof.

[0010] In some embodiments, the coating layer further comprises graphene.

[0011] In certain embodiments, the coating layer has a thickness less than 10 nm.

[0012] In some embodiments, the coating layer has a thickness in the range of 6-8 nm.

[0013] In certain embodiments, the core includes at least one of aluminum, copper, nickel, tin, zinc, chromium, iron, lithium, cobalt, oxides or alloys thereof.

[0014] In certain embodiments, the ratio of metal to metal oxide in the core is 1:1.

[0015] In certain embodiments, the diameter of the core is in the range of 0-100 nm.

[0016] According to an embodiment of the present application, an apparatus for preparing a composite current collector is provided. The apparatus comprises a conveying assembly, a spraying device, and a coating assembly. The conveying assembly is used to convey a base film. The spraying device is used to spray composite particles to form an intermediate layer on the base film. The coating assembly is used to form a metal layer on the intermediate layer.

[0017] In certain embodiments, the spraying device includes: a cavity, an air inlet pipe, a feed port, and a nozzle. The air inlet pipe extends from one end of the cavity into the cavity. The feed port extends from one side of the cavity into the cavity. The nozzle connects the air inlet pipe and the feed port within the cavity and extends toward the other end of the cavity. The air inlet pipe is configured to pass a carrier gas into the nozzle, and the feed port is configured to pass the composite particles into the nozzle. The composite particles are sprayed from the nozzle toward the base film via the carrier gas.

[0018] In some embodiments, the spraying device further comprises an auxiliary air inlet pipe connected to a discharge port adjacent to the nozzle, and configured to introduce the carrier gas to change the angle at which the composite particles exit the discharge port.

[0019] In some embodiments, the angle between the discharge port of the nozzle and the surface to be coated of the base film is in the range of 0 to 90 degrees.

[0020] In some embodiments, the angle between the discharge port of the nozzle and the surface to be coated of the base film is 45 degrees.

[0021] In some embodiments, the distance between the discharge port of the nozzle and the base film is between 100-300 mm, the spraying flow rate is 3000 sccm, and the spraying power is in the range of 0-200 kW.

[0022] This application proposes a method for preparing a composite current collector for a lithium battery. The method comprises forming an intermediate layer on a base film, the intermediate layer comprising composite particles, the composite particles comprising a conductive core and a thermoplastic coating, the core being fully or partially encapsulated by the coating and distributed on the base film; and forming a metal layer on the composite particle layer.

[0023] In the composite current collector proposed in this application, the composite particles are used as an intermediate layer to improve the bonding force between the evaporated metal layer and the base film without affecting the overall conductivity, thereby ensuring the stability of the subsequent battery during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the following detailed description, they are used to explain the present application but do not constitute a limitation of the present application. In the accompanying drawings:

[0025] FIG1A shows a schematic structural diagram of a composite particle according to an embodiment of the present application.

[0026] FIG1B shows a schematic structural diagram of a composite current collector according to an embodiment of the present application.

[0027] FIG2 is a schematic diagram illustrating an apparatus for preparing a composite current collector for a lithium battery according to an embodiment of the present application.

[0028] FIG3A illustrates a cross-sectional view of a spraying device according to an embodiment of the present application.

[0029] FIG. 3B illustrates a cross-sectional view of a spraying device according to another embodiment of the present application.

[0030] FIG4 illustrates the process steps of a method for preparing a composite current collector for a lithium battery according to an embodiment of the present application. DETAILED DESCRIPTION

[0031] The following disclosure provides a variety of implementations or illustrations that can be used to implement different features of the present disclosure. The specific examples of components and configurations described below are intended to simplify the present disclosure. As will be appreciated, these descriptions are illustrative only and are not intended to limit the present disclosure. For example, in the description below, forming a first feature on or above a second feature may include certain embodiments in which the first and second features are in direct contact with each other; and may also include certain embodiments in which additional components are formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may reuse component symbols and / or labels in multiple embodiments. Such repetition is for the purposes of brevity and clarity and does not, in itself, represent a relationship between the different embodiments and / or configurations discussed.

[0032] Furthermore, spatially relative terms such as "below," "beneath," "below," "above," and the like may be used herein to facilitate description of the relationship of one component or feature depicted in a figure relative to one or more other components or features. These spatially relative terms are intended to encompass various orientations of the device during use or operation, in addition to the orientation depicted in the figures. The device may be placed in other orientations (e.g., rotated 90 degrees or in other orientations), and these spatially relative descriptive terms should be interpreted accordingly.

[0033] Although the numerical ranges and parameters used to define the broader scope of this application are approximate, the numerical values ​​of the specific examples have been presented herein as precisely as possible. However, any numerical value inherently and inevitably contains standard deviations resulting from individual testing methods. As used herein, "about" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specified value or range. Alternatively, the term "about" means that the actual value falls within an acceptable standard error of the mean, as determined by one of ordinary skill in the art. It should be understood that, except in the experimental examples, or unless otherwise expressly indicated, all ranges, amounts, values, and percentages used herein (e.g., to describe material amounts, time periods, temperatures, operating conditions, quantitative ratios, and the like) are modified by the word "about." Therefore, unless otherwise indicated, the numerical parameters disclosed in this specification and the appended claims are approximate and may be modified as needed. At a minimum, these numerical parameters should be understood to include the number of significant digits indicated and to apply normal rounding. Herein, numerical ranges are expressed from one endpoint to another endpoint or between two endpoints; unless otherwise stated, the numerical ranges described herein include the endpoints.

[0034] Referring to Figure 1A , FIG1A illustrates a schematic structural diagram of a composite particle 20 according to one embodiment of the present application. In certain embodiments, the composite particle 20 can be used to prepare a composite current collector for a lithium battery. The composite current collector prepared using the composite particle 20 can enhance the bonding strength between the base film and subsequent metal layers, improving the stability of the battery during operation. In certain embodiments, the composite particle 20 can include a conductive core 21 and a thermoplastic coating 22.

[0035] The core 21 may include at least one of aluminum, copper, nickel, tin, zinc, chromium, iron, lithium, cobalt, and oxides or alloys thereof. In some embodiments, the core 21 may include a metal and a metal oxide in a ratio of 1:1. The diameter of the core 21 may be in the range of 0-100 nm.

[0036] The coating layer 22 may include any one of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polyoxymethylene, polycarbonate, polyphenylene oxide, polysulfone, and polyethylene terephthalate, or a mixture thereof. In certain embodiments, the coating layer 22 may also be doped with graphene. In certain embodiments, the coating layer 22 has a thickness of less than 10 nm. Preferably, the coating layer 22 has a thickness in the range of 6-8 nm.

[0037] Referring to FIG. 1B , FIG. 1B illustrates a schematic structural diagram of a composite current collector 30 according to one embodiment of the present application. In certain embodiments, the composite current collector 30 can be used in a lithium battery. In certain embodiments, the composite current collector 30 includes a base film XM, an intermediate layer ML composed of the composite particles 20 shown in FIG. 1A , and a metal layer NL formed by vapor deposition on the base film XM and the intermediate layer ML.

[0038] When the composite particles 20 are sprayed onto the surface of the base film XM, in a vacuum and high-temperature environment, the thermoplastic polymer material of the coating layer 22 of the composite particles 20 softens or melts upon exposure to heat, becoming plastic and integrating well with the base film XM. The core 21 is then partially or fully encapsulated and distributed on the base film XM. Because the coating layer 22 is less than 10 nm thick, the conductive particles of the core 21 form a conductive seed layer on the base film XM due to the electron tunneling effect. As the later-deposited metal layer NL thickens, it improves the bonding between the evaporated metal layer NL and the base film XM while maintaining overall conductivity, ensuring the stability of the subsequent battery during operation.

[0039] Figure 2 illustrates a schematic diagram of an apparatus 10 for preparing a composite current collector for a lithium battery according to one embodiment of the present application. In certain embodiments, apparatus 10 can be used to prepare a composite current collector 30 as shown in Figure 1B . Apparatus 10 can coat both sides of a base film XM individually or simultaneously. In certain embodiments, apparatus 10 includes a conveyor assembly 11, spraying devices 12 and 12', and a coating assembly 13.

[0040] The conveyor assembly 11 is used to convey the base film XM. In some embodiments, the conveyor assembly 11 includes an unwinding roller 111, conveying rollers 112 and 112', a transition roller 113, and a take-up roller 114. After being unwound by the unwinding roller 111, the base film XM is guided sequentially by the conveying roller 112, the transition roller 113, and the conveying roller 112', and finally taken up by the take-up roller 114. In some embodiments, the base film XM is a thermoplastic polymer base film. In some embodiments, the base film XM includes any one of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, polyacrylonitrile, cellulose acetate, polystyrene, or polyimide, or a mixture thereof. In some embodiments, the base film XM has a thickness of 0 to 20 μm.

[0041] The spraying devices 12 and 12' and the coating assembly 13 are disposed on the same side of the apparatus 10. The spraying devices 12 and 12' are configured to spray composite particles 20 on different surfaces of the base film XM, respectively, to form the middle layer ML on different surfaces of the base film XM.

[0042] Referring to Figure 3A, Figure 3A illustrates a cross-sectional view of a spraying device 12 according to an embodiment of the present application. The structures of the spraying devices 12 and 12' are basically the same, so they are not described in detail. In some embodiments, the spraying device 12 includes a cavity 120, an air inlet pipe 121, a feed port 122, and a nozzle 123. In some embodiments, the air inlet pipe 121 extends from one end of the cavity 120 to the interior of the cavity 120, and the air inlet pipe 121 is configured to pass a carrier gas to the nozzle 123. In some embodiments, the feed port 122 extends from one side of the cavity 120 to the interior of the cavity 120, and the feed port 122 is configured to pass composite particles 20 to the nozzle 123. In some embodiments, the nozzle 123 connects the air inlet pipe 121 and the feed port 122 in the cavity 120, wherein the composite particles 20 are sprayed from the nozzle 123 to the base film XM through the carrier gas.

[0043] In some embodiments, the angle between the discharge port 123H of the nozzle 123 and the surface of the base film XM to be coated is in the range of 0-90 degrees, preferably 45 degrees. In some embodiments, the distance between the discharge port 123H of the nozzle 123 and the surface of the base film XM to be coated is between 100-300 mm. In some embodiments, the spraying device 12 sprays the composite particles at a spray flow rate of 3000 sccm and a spray power in the range of 0-200 kW.

[0044] Referring to Figure 3B, Figure 3B illustrates a cross-sectional view of a spraying device 12 according to another embodiment of the present application. The spraying device 12 of the embodiment of Figure 3B is substantially similar to the spraying device 12 of the embodiment of Figure 3A, with the only difference being that the spraying device 12 of the embodiment of Figure 3B further includes an auxiliary air inlet pipe 124, and therefore the same parts will be omitted here to save space. In certain embodiments, the auxiliary air inlet pipe 124 is connected between the air inlet pipe 121 and the nozzle 123. In certain embodiments, the auxiliary air inlet pipe 124 is connected to a position adjacent to the discharge port 123H, and is configured to introduce a carrier gas into the nozzle 123 to change the angle at which the composite particles 20 leave the discharge port 123H, so that the composite particles 20 are more fully mixed to obtain a more uniform intermediate layer ML after being sprayed on the base film XM.

[0045] Referring again to Figure 2, the coating assembly 13 is configured to form a metal layer NL on the middle layer ML. In some embodiments, the coating assembly 13 evaporates the target material to generate a vapor including target material components. In some embodiments, the coating assembly 13 includes crucibles 131 and 131', which are used to carry the target material. In some embodiments, the coating assembly 12 also includes a target material conveying device and a heating device (not shown), and the target material conveying device is configured to deliver the target material to the crucibles 131 and 131'. The heating device is, for example, but not limited to, an electron gun to evaporate the target material in the crucibles 131 and 131'. It should be noted that the present application does not limit the specific implementation method of the heating device. As long as the target material can be evaporated to evaporate the base film XM, it should fall within the scope of the present application.

[0046] The spraying device 12 corresponds to the crucible 131 and the conveying roller 112, and the side of the base film XM carried by the conveying roller 112 that faces the spraying device 12 and the crucible 131 will be coated. In addition, the spraying device 12' corresponds to the crucible 131' and the conveying roller 112', and the side of the base film XM carried by the conveying roller 112' that faces the spraying device 12' and the crucible 131' will be coated.

[0047] 1A, 1B and 2, the preparation process of the composite current collector 30 is roughly as follows:

[0048] First, the base film XM is mounted on the conveyor assembly 11. Next, the base film XM can be pre-treated with plasma. For example, a plasma can be generated by discharging a reactive gas (such as, but not limited to, Ar, O2, or N2). The plasma contains high-energy substances such as electrons, ions, free radicals, and ultraviolet rays. The plasma acts on the base film XM, and the active particles and high-energy rays contained therein react and collide with the organic pollutant molecules on the surface of the base film XM to form small volatile molecules, which are removed from the surface, achieving a cleaning effect and activating the surface. Next, the coating assembly 13 is preheated, and the chamber of the equipment 10 is evacuated to 0.1-10 Pa. Next, the spraying devices 12 and 12' are turned on to spray the composite particles 20 to form an intermediate layer ML on both sides of the base film XM. Finally, the target material is evaporated by the coating assembly 13, and a metal layer NL is formed on the intermediate layer ML by evaporation, thereby obtaining a composite current collector 30.

[0049] 4 illustrates the process steps of a method 40 for preparing a composite current collector for a lithium battery according to an embodiment of the present application. In certain embodiments, the method 40 can be performed by the apparatus 10 to obtain the composite current collector 30 as shown in FIG1B.

[0050] Provided that similar results can be obtained, this application is not limited to executing the method 40 in its entirety. Method 40 may generally include steps 41 and 42. In step 41, an intermediate layer may be formed on the base film, wherein the intermediate layer may include composite particles. The composite particles may include a conductive core and a thermoplastic coating. The core may be fully or partially encapsulated by the coating and distributed on the base film. In step 42, a metal layer may be formed on the composite particle layer to obtain a composite current collector.

[0051] For the composite current collector 30 formed by various composite particles 20, the applicant conducted a series of experiments to verify its peel strength, tensile strength and elongation at break. The peel strength test refers to the "GB / T 2792-2014 Test method for peel strength of adhesive tape". Peel strength refers to the ease of separation between materials, which depends on the bonding between the surfaces of the two materials. When the peel strength is high, it means that the intermediate layer and the base film are tightly bonded, and the finished product has good stability during subsequent processing and actual application in batteries. The metal layer will not peel off, and the relevant tensile strength will also be improved. The tensile strength test is based on the "GB / T 5230-2020 Electrolytic copper foil for printed circuit boards" and is carried out using a universal experimental tensile machine. The experimental results are listed in Table 1 below.

[0052] Table 1

[0053] The coating layer 22 of the composite particle 20 of Example 1 is PET with a thickness of 8 nm, and the core 21 is an aluminum particle with a diameter of 6 nm;

[0054] The coating layer 22 of the composite particle 20 in Example 2 is PET with a thickness of 6 nm and doped with 0.1% graphene, and the core 21 is an aluminum particle with a diameter of 4 nm;

[0055] The coating layer 22 of the composite particle 20 of Example 3 is PET with a thickness of 8 nm, and the core 21 is a copper particle with a diameter of 6 nm;

[0056] The coating layer 22 of the composite particle 20 of Example 4 is PET with a thickness of 8 nm, and the core 21 is an aluminum oxide particle with a diameter of 4 nm;

[0057] The coating layer 22 of the composite particles 20 of Example 5 is PET with a thickness of 8 nm, and the core 21 is a mixture of alumina particles with a diameter of 4 nm and aluminum particles with a diameter of 4 nm in a ratio of 1:1.

[0058] From the above experimental results, it can be seen that if the core 21 includes aluminum particles, due to its lighter relative atomic mass, it has relatively better adhesion to the base film. The addition of graphene helps to improve overall adhesion and mechanical strength. At the same time, the smaller the nanoparticle size, the denser the film formed is theoretically, and the mechanical properties are better. In addition, the composite current collector 30 prepared using composite particles 20 can further improve the fracture strength and elongation at break. Compared with the composite current collector prepared without composite particles 20, the elongation at break can be optimized by 4 to 5 times.

[0059] As used herein, the terms "approximately," "substantially," "substantially," and "about" are used to describe and take into account small variations. When used in conjunction with an event or circumstance, the terms may refer to instances where the event or circumstance occurred exactly as well as instances where the event or circumstance occurred very approximately. As used herein with respect to a given value or range, the term "approximately" generally means within ±10%, ±5%, ±1%, or ±0.5% of the given value or range. Ranges may be expressed herein as from one endpoint to another or between two endpoints. Unless otherwise specified, all ranges disclosed herein include endpoints. The term "substantially coplanar" may refer to two surfaces that are positioned along the same plane within a few micrometers (μm), for example, within 10 μm, within 5 μm, within 1 μm, or within 0.5 μm positioned along the same plane. When referring to a value or characteristic that is "substantially" the same, the term may refer to a value that is within ±10%, ±5%, ±1%, or ±0.5% of the average of the stated values.

[0060] As used herein, the terms "approximately," "substantially," "essentially," and "about" are used to describe and explain small variations. When used in conjunction with an event or circumstance, the terms may refer to instances where the event or circumstance occurred exactly as well as instances where the event or circumstance occurred very approximately. For example, when used in conjunction with a numerical value, the terms may refer to a range of variation of less than or equal to ±10% of the numerical value, e.g., less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, two values ​​may be considered "substantially" or "approximately" the same if the difference between them is less than or equal to ±10% of the mean of the values ​​(e.g., less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%). For example, "substantially" parallel can refer to an angular variation of less than or equal to ±10° relative to 0°, e.g., less than or equal to ±5°, less than or equal to ±4°, less than or equal to ±3°, less than or equal to ±2°, less than or equal to ±1°, less than or equal to ±0.5°, less than or equal to ±0.1°, or less than or equal to ±0.05°. For example, "substantially" perpendicular can refer to an angular variation range of less than or equal to ±10° relative to 90°, for example, less than or equal to ±5°, less than or equal to ±4°, less than or equal to ±3°, less than or equal to ±2°, less than or equal to ±1°, less than or equal to ±0.5°, less than or equal to ±0.1°, or less than or equal to ±0.05°.

[0061] For example, two surfaces may be considered coplanar or substantially coplanar if the displacement between the two surfaces is equal to or less than 5 μm, equal to or less than 2 μm, equal to or less than 1 μm, or equal to or less than 0.5 μm. A surface may be considered planar or substantially planar if the displacement between any two points on the surface relative to the plane is equal to or less than 5 μm, equal to or less than 2 μm, equal to or less than 1 μm, or equal to or less than 0.5 μm.

[0062] As used herein, the singular terms "a," "an," and "the" may include plural referents unless the context clearly dictates otherwise. In the description of some embodiments, a component provided "on" or "over" another component may encompass both the case where the former component is directly on (e.g., physically in contact with) the latter component and the case where one or more intermediate components are located between the former and the latter component.

[0063] As used herein, spatially relative terms such as "below," "beneath," "lower," "above," "upper," "lower," "left," "right," etc., may be used herein for ease of description to describe the relationship of one component or feature to another component or feature as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein should be interpreted accordingly. It should be understood that when a component is referred to as being "connected to" or "coupled to" another component, it can be directly connected or coupled to the other component or intervening components may be present.

[0064] The foregoing summarizes several embodiments and detailed features of the present disclosure. The embodiments described in this disclosure can be readily used as a basis for designing or modifying other processes and structures for performing the same or similar purposes and / or obtaining the same or similar advantages of the embodiments introduced herein. These equivalent constructions do not depart from the spirit and scope of the present disclosure and various changes, substitutions, and modifications may be made without departing from the spirit and scope of the present disclosure.

Claims

1. A composite current collector for a lithium battery, characterized in that, Comprising: A base film, an intermediate layer, and a metal layer formed on top of the intermediate layer; The intermediate layer includes composite particles, and the composite particles include a conductive core and a thermoplastic coating layer. The core is distributed on the base film entirely or partially wrapped by the coating layer to enhance the mechanical strength of the composite current collector so that the composite current collector is not easily deformed by heat shrinkage.

2. The composite current collector according to claim 1, wherein The elongation at break of the composite current collector is in the range of 31.2% - 48.2%.

3. The composite current collector according to claim 1, wherein The peel strength of the composite current collector is in the range of 6.8 - 9.3 N / cm.

4. The composite current collector according to claim 1, wherein The tensile strength of the composite current collector is in the range of 182 - 233 MPa.

5. The composite current collector according to claim 1, wherein The coating layer includes any one or a mixture of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polyoxymethylene, polycarbonate, polyphenylene ether, polysulfone, polyethylene terephthalate, etc.

6. The composite current collector according to claim 5, wherein The coating layer further includes graphene.

7. The composite current collector according to claim 1, wherein The thickness of the coating layer is in the range less than 10 nm.

8. The composite current collector according to claim 7, wherein Characterized in that, The thickness of the coating layer is in the range of 6 - 8 nm.

9. The composite current collector according to claim 1, wherein The core includes at least one of aluminum, copper, nickel, tin, zinc, chromium, iron, lithium, cobalt, and their oxides or alloys, etc.

10. The composite current collector according to claim 1, wherein The ratio of the metal and metal oxide in the core is 1:

1.

11. The composite current collector according to claim 1, wherein The diameter of the core is in the range of 0 - 100 nm.

12. An apparatus for preparing a composite current collector, characterized in that, Comprising: A conveying component for conveying the base film; A spraying device for spraying composite particles to form an intermediate layer on the base film; And A coating component for forming a metal layer on the intermediate layer.

13. The device according to claim 12, characterized in that, The spraying device includes: A cavity; An air inlet pipe extending into the cavity from one end of the cavity; A feed port extending into the cavity from one side of the cavity; A nozzle connected to the air inlet pipe and the feed port in the cavity and extending to the other end of the cavity; and; Wherein the air inlet pipe is configured to introduce a carrier gas into the nozzle, the feed port is configured to introduce the composite particles into the nozzle, and the composite particles are sprayed from the nozzle to the base film through the carrier gas.

14. The device according to claim 13, characterized in that, The spraying device further includes: An auxiliary air inlet pipe connected to the discharge port adjacent to the nozzle and configured to introduce the carrier gas to change the angle of the composite particles leaving the discharge port.

15. The device according to claim 12, characterized in that, The angle between the discharge port of the nozzle and the surface of the base film to be coated is in the range of 0 to 90 degrees.

16. The device according to claim 15, characterized in that, The angle between the discharge port of the nozzle and the surface of the base film to be coated is 45 degrees.

17. The device according to claim 12, characterized in that, The distance between the discharge port of the nozzle and the base film is between 100 - 300 mm, the spraying flow rate is 3000 sccm, and the spraying power is in the range of 0 - 200 KW.

18. A method for preparing a composite current collector for a lithium battery, characterized in that, Comprising: Forming an intermediate layer on the base film, the intermediate layer includes composite particles, the composite particles include a conductive core and a thermoplastic coating layer, and the core is distributed on the base film entirely or partially wrapped by the coating layer; and Forming a metal layer on top of the composite particle layer.

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