Low swelling composite current collector and manufacturing method thereof

Abstract

The low swelling composite current collector includes a thin film substrate layer having a crosslinking layer and a metal layer provided in sequence on two opposite surfaces of the thin film substrate layer, and the crosslinking layer is formed by crosslinking the thin film substrate layer with a surface crosslinking agent applied to the thin film substrate layer through chemical bonding. By providing the crosslinking layer and the metal layer in sequence on the two opposite surfaces of the thin film substrate layer, more chemical bonds are formed on the surface of the thin film substrate layer, and the bonding strength between the metal layer and the thin film substrate layer is improved, the solubility of the thin film substrate layer in the electrolyte of the battery is reduced, the phenomenon of swelling occurring from the thin film substrate layer is reduced, the chemical bonds between the metal layer and the thin film substrate layer are not broken, the peeling strength between the metal layer and the thin film substrate layer is improved, and the metal layer is less likely to fall off from the thin film substrate layer, ensuring the electrical performance, safety and internal resistance stability of the battery.

Description

[Technical field]

[0001] The present invention relates to the technical field of secondary batteries, and in particular to a low-swelling composite current collector and a method for producing the same. [Background technology]

[0002] Currently, there are two types of composite current collectors: copper current collectors and aluminum current collectors. The copper current collectors and aluminum current collectors are both composed of two parts, including a thin film substrate layer in the middle and metal layers on the two opposite surfaces of the thin film substrate layer. The thickness of the metal layer is generally about 1 μm. The composite current collectors are manufactured by deposition process, and the thin film substrate layer is often made of polymer materials such as polyethylene terephthalate (PET), which contain a large amount of ester groups. When the electrolyte in the battery contacts with the polymer material, the ester group in the polymer material encounters and dissolves with the ester group in the electrolyte, which makes the thin film substrate layer prone to swelling during long-term use of the battery, destroying the chemical bond between the metal layer and the thin film substrate layer, gradually worsening the peeling force between the metal layer and the thin film substrate layer of the composite current collector, making it prone to the detachment of the metal layer and the thin film substrate layer, which in turn affects the positive and negative electrode interfaces inside the battery, worsening the electrical performance of the battery and affecting the safety of the battery. On the other hand, after the polymer material dissolves and enters the electrolyte, the viscosity of the electrolyte also increases, which increases the hindrance of ion transmission and increases the internal resistance of the battery in the later stage of the battery. Summary of the Invention [Problem to be solved by the invention]

[0003] It is therefore necessary to provide a low-swelling composite current collector and a manufacturing method thereof that can reduce the solubility of the thin film substrate layer in the battery's electrolyte, thereby significantly reducing the phenomenon of swelling of the thin film substrate layer, and improve the peeling force between the metal layer and the thin film substrate layer, making the metal layer and the thin film substrate layer less likely to fall off, thereby ensuring the electrical performance, safety, and internal resistance stability of the battery. [Means for solving the problem]

[0004] A thin film substrate layer having a bridge layer and a metal layer provided in order on two opposite surfaces of the thin film substrate layer, the crosslinked layer is formed by crosslinking the thin film base layer and the surface crosslinking agent applied to the thin film base layer through a chemical bonding action. Low swelling composite current collector.

[0005] A crosslinking layer and a metal layer are sequentially provided on two opposite surfaces of the thin film substrate layer, and the crosslinking layer is formed by crosslinking the surface crosslinking agent applied to the thin film substrate layer and the thin film substrate layer through a chemical bonding action, thereby forming more chemical bonds on the surface of the thin film substrate layer, improving the bonding strength between the metal layer and the thin film substrate layer, and also reducing the solubility of the thin film substrate layer in the electrolyte of the battery. As a result, the phenomenon of swelling of the thin film substrate layer is greatly reduced, the chemical bonds between the metal layer and the thin film substrate layer are not broken, the peeling force between the metal layer and the thin film substrate layer is improved, and the metal layer and the thin film substrate layer are not easily detached from each other, thereby ensuring the electrical performance and safety of the battery. Furthermore, since almost no components from the thin film substrate layer are dissolved in the electrolyte of the battery, the viscosity of the electrolyte does not increase, and thus the internal resistance stability of the battery can be effectively ensured.

[0006] In one embodiment thereof, the thin film substrate layer comprises at least one of an insulating polymeric material, an insulating polymeric composite material, a conductive polymeric material, and a conductive polymeric composite material.

[0007] Here, the insulating polymer material includes at least one of polyamide (PA), polyterephthalate, polyimide (PI), polyethylene (PE), polypropylene (PP), polystyrene (PPE), polyvinyl chloride (PVC), aramid, acrylonitrile-butadiene-styrene copolymer (ABS), polybutylene terephthalate (PET), polyparaphenylene terephthalamide (PPTA), polypropylene (PPE), polyoxymethylene (POM), epoxy resin, phenolic resin, polytetrafluoroethylene (PTEE), polyvinylidene fluoride (PVDF), silicone rubber, polycarbonate (PC), polyvinyl alcohol (PVA), polyethylene glycol (PEG), cellulose, starch, protein, derivatives thereof, crosslinked products thereof, and copolymers thereof.

[0008] The insulating polymer composite material is a composite material formed of an insulating polymer material and an inorganic material, where the inorganic material may be at least one of a ceramic material, a glass material, and a ceramic composite material.

[0009] The conductive polymer material is at least one of doped polythiazyl and doped polyacetylene.

[0010] The conductive polymer composite material is a composite material formed of an insulating polymer material and a conductive material.

[0011] In one embodiment thereof, the thin film substrate layer includes at least one of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polyphenylene sulfide (PPS).

[0012] In one embodiment thereof, the metal layer is a metallic aluminum layer or a metallic copper layer.

[0013] In one embodiment thereof, the thin film substrate layer has a thickness ranging from 1 μm to 25 μm, and the metal layer has a thickness ranging from 0.5 μm to 2.5 μm.

[0014] In one embodiment, the thickness of the cross-linked layer ranges from 0.1 μm to 0.5 μm.

[0015] In one embodiment, the thickness of the cross-linked layer ranges from 0.2 μm to 0.4 μm.

[0016] The present application provides a method for producing the above-mentioned low-swelling composite current collector, comprising the steps of: applying the cross-linking agent to two opposite surfaces of the thin film substrate layer; catalyzing the crosslinking agent and the thin film substrate layer to crosslink the crosslinking agent and the thin film substrate layer and form the crosslinked layers on two opposing surfaces of the thin film substrate layer; and depositing the metal layer on the surface of the bridging layer. A method for making a low swelling composite current collector is further provided.

[0017] In one embodiment, the manner of catalyzing the cross-linking agent and the thin film substrate layer includes UV irradiation or heating.

[0018] In one embodiment, the temperature at which the crosslinking agent and the thin film substrate layer are crosslinked is 50°C to 200°C. Effect of the Invention

[0019] In the above embodiment, the crosslinking layer and the metal layer are sequentially provided on two opposite surfaces of the thin film substrate layer, and the crosslinking layer is formed by crosslinking the surface crosslinking agent applied to the thin film substrate layer and the thin film substrate layer through chemical bonding action, so that more chemical bonds are formed on the surface of the thin film substrate layer, and the bonding strength between the metal layer and the thin film substrate layer can be improved, and the solubility of the thin film substrate layer in the electrolyte of the battery can be reduced, so that the swelling phenomenon of the thin film substrate layer is greatly reduced, the chemical bond between the metal layer and the thin film substrate layer is not broken, the peeling strength between the metal layer and the thin film substrate layer is improved, and the metal layer and the thin film substrate layer are not easily detached, so that the electrical performance and safety of the battery are ensured, and since there is almost no component dissolved in the electrolyte of the battery from the thin film substrate layer, the viscosity of the electrolyte does not increase, and thus the stability of the internal resistance of the battery can be effectively ensured. The method of catalyzing the crosslinking agent and the thin film substrate layer is ultraviolet irradiation or heating, so that the speed of crosslinking between the crosslinking agent and the thin film substrate layer can be increased. [Brief description of the drawings]

[0020] [Figure 1] FIG. 2 is a structural schematic diagram of a composite current collector according to an embodiment of the present invention. [Diagram 2] 1 is a flow chart of steps for a method of making a composite current collector according to one embodiment of the present invention. [Diagram 3] 4 is a flowchart showing steps of a method for producing a composite current collector according to a comparative example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The drawings constituting a part of this application are used to provide a further understanding of the present invention, and the schematic embodiments of the present invention and the description thereof are intended to interpret the present invention and are not intended to unduly limit the present invention.

[0022] In order to more clearly describe the technical solutions in the embodiments of the present invention, the drawings that need to be used in the description of the embodiments will be briefly described below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can also obtain other drawings based on these drawings without performing any creative work.

[0023] In order to more clearly explain the above objects, features and advantages of the present invention, the following detailed description will be given of specific embodiments of the present invention with reference to the drawings. In the following description, many specific details will be described in order to fully understand the present invention. However, the present invention is not limited to the specific embodiments disclosed below, because the present invention can be embodied in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present invention.

[0024] In describing the present invention, the orientations and positional relationships indicated by terms such as "center," "longitudinal," "lateral," "length," "width," "thickness," "up," "down," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are based on the orientations and positional relationships shown in the drawings, and are merely intended to facilitate and simplify the description of the present invention, and are not intended to indicate or imply that the referred devices or elements necessarily have a specific orientation or are required to be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present application.

[0025] Additionally, the terms "first", "second", etc. are for descriptive purposes only and should not be understood as indicating or implying a relative importance or number of the technical features referred to. Thus, a feature qualified as "first", "second", etc. may explicitly or implicitly include at least one of the feature. In the present description, unless otherwise specified, "plurality" means at least two, e.g., two, three, etc.

[0026] In the present invention, unless otherwise clearly specified and limited, the terms "attached", "connected", "connected", "fixed" and the like should be interpreted broadly. For example, it may be a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate medium, a communication inside two parts, or a relationship of interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific situation.

[0027] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first feature and the second feature are in direct contact with each other, or that the first feature and the second feature are in indirect contact with each other via an intermediate medium. Furthermore, a first feature being "above," "above," and "on the upper surface" of a second feature means that the first feature may be directly above and diagonally above the second feature, or simply means that the first feature is higher in horizontal height than the second feature. A first feature being "below," "below," and "on the lower surface" of a second feature means that the first feature may be directly below and diagonally below the second feature, or simply means that the first feature is lower in horizontal height than the second feature.

[0028] It should be noted that when an element is referred to as "fixed" or "mounted" on another element, the element may be directly on the other element, or there may be intervening elements present. When an element is referred to as being "connected" to another element, it may be directly connected to the other element, or there may be intervening elements present at the same time. As used herein, the terms "vertical," "horizontal," "top," "bottom," "left," "right," and similar designations are for illustrative purposes only and do not represent the only embodiments.

[0029] Referring to FIG. 1, an embodiment of the present invention provides a low-swelling composite current collector 10, which includes a thin film substrate layer 100, a crosslinking agent, and a metal layer 300, in which the thin film substrate layer 100 is disposed in the middle, and a crosslinking layer 200 and a metal layer 300 are disposed in sequence on two opposite surfaces of the thin film substrate layer 100. Specifically, the composite current collector 10 has a puncture strength of ≧50 gf, a MD tensile strength of ≧150 MPa, a TD tensile strength of ≧150 MPa, an MD elongation of ≧10%, and a TD elongation of ≧10%. Exemplarily, the composite current collector 10 has a puncture strength of 70 gf, a MD tensile strength of 180 MPa, and a TD tensile strength of 180 MPa. The MD elongation of 20% and the TD elongation of 20%. Note that MD (Machine Direction) means the machine direction, and TD (Transverse Direction, perpendicular to the mechanical direction) means the transverse direction.

[0030] The cross-linked layer 200 is formed by cross-linking the thin film substrate layer 100 and the surface cross-linking agent applied to the thin film substrate layer 100 through chemical bonding. Specifically, the thin film substrate layer 100 has a first surface and a second surface configured opposite to each other in the thickness direction. The cross-linking agent is applied to the two opposite surfaces of the thin film substrate layer 100 through chemical bonding, which means that the cross-linking agent is applied to the first surface and the second surface of the thin film substrate layer 100, respectively, and cross-links with the material of the thin film substrate layer 100.

[0031] The cross-linking layer 200 and the metal layer 300 are sequentially provided on two opposite surfaces of the thin film substrate layer 100, and the cross-linking layer 200 is formed by cross-linking the thin film substrate layer 100 and a surface cross-linking agent applied to the thin film substrate layer 100 through a chemical bonding action, thereby forming many chemical bonds on the surface of the thin film substrate layer 100, which can improve the bonding strength between the metal layer 300 and the thin film substrate layer 100 and can also reduce the solubility of the thin film substrate layer 100 in the electrolyte of the battery. As a result, the thin film substrate layer 100 can be easily formed. The phenomenon of swelling of the material layer 100 is greatly reduced, the chemical bond between the metal layer 300 and the thin film substrate layer 100 is not destroyed, the peeling force between the metal layer 300 and the thin film substrate layer 100 is improved, and the metal layer 300 and the thin film substrate layer 100 are less likely to fall off, thereby ensuring the electrical performance and safety of the battery, and there is almost no component from the metal layer 300 and the thin film substrate layer 100 that dissolves in the battery's electrolyte, so the viscosity of the electrolyte does not increase, and thus the internal resistance stability of the battery can be effectively ensured.

[0032] Referring to FIG. 1, according to some embodiments of the present application, the thin film substrate layer 100 preferably includes at least one of an insulating polymer material, an insulating polymer composite material, a conductive polymer material, and a conductive polymer composite material. The thin film substrate layer 100 has a puncture strength of ≧100gf, an MD tensile strength of ≧200MPa, and a TD tensile strength of ≧200MPa. The MD elongation is ≧30% and the TD elongation is ≧30%. Exemplarily, the thin film substrate layer 100 has a puncture strength of 120gf, an MD tensile strength of 250MPa, and a TD tensile strength of 250MPa. The MD elongation is 40% and the TD elongation is 40%.

[0033] The insulating polymer material may be at least one of polyamide (PA), polyterephthalate, polyimide (PI), polyethylene (PE), polypropylene (PP), polystyrene (PPE), polyvinyl chloride (PVC), aramid, acrylonitrile-butadiene-styrene copolymer (ABS), polybutylene terephthalate (PET), polyparaphenylene terephthalamide (PPTA), polypropylene (PPE), polyoxymethylene (POM), epoxy resin, phenolic resin, polytetrafluoroethylene (PTEE), polyvinylidene fluoride (PVDF), silicone rubber, polycarbonate (PC), polyvinyl alcohol (PVA), polyethylene glycol (PEG), cellulose, starch, protein, derivatives thereof, cross-linked products thereof, and copolymers thereof.

[0034] The insulating polymer composite material may be a composite material formed of an insulating polymer material and an inorganic material, where the inorganic material may be at least one of a ceramic material, a glass material, and a ceramic composite material.

[0035] The conductive polymer material may be at least one of doped polythiazyl and doped polyacetylene.

[0036] The conductive polymer composite material may be a composite material formed of an insulating polymer material and a conductive material. Specifically, the conductive material may be at least one of a conductive carbon material, a metal material, and a composite conductive material. More specifically, the conductive carbon material is at least one selected from carbon black, carbon nanotubes, graphite, acetylene black, and graphene. The metal material is at least one selected from metallic nickel, metallic iron, metallic copper, metallic aluminum, or an alloy of the above metals. The composite conductive material is at least one selected from graphite powder coated with metallic nickel and carbon fiber coated with metallic nickel.

[0037] Referring to FIG. 1 and according to some embodiments of the present application, preferably, the crosslinking agent is selected from the group consisting of polyisocyanates (JQ-1, JQ-1E, JQ-2E, JQ-3E, JQ-4, JQ-5, JQ-6, PAPI, emulsifiable MDI, tetraisocyanate), polyamines (propylene diamine, MOCA), polyols (polyethylene glycol, polypropylene glycol, trimethylolpropane, trimethylolethane), glycidyl ethers (polypropylene glycol glycidyl ether), inorganics (zinc oxide, aluminum chloride, aluminum sulfate, sulfur, boric acid, borax, chromium nitrate), organics (styrene, a-methylstyrene, acrylonitrile, acrylic acid, methacrylic acid, glyoxal, aziridinyl ether, methyl methacrylate ... The crosslinking agent may be at least one of the following: silicone-based (ethyl orthosilicate, methyl orthosilicate, trimethoxysilane), benzenesulfonic acid-based (p-toluenesulfonic acid, p-toluenesulfonyl chloride), acrylate-based (1,4-butanediol diacrylate, ethylene glycol dimethacrylate, TAC, butyl acrylate, HEA, HPA, HEMA, HPMA, MMA), organic peroxide (dicumyl peroxide, bis(2,4-dichlorobenzoyl) peroxide), metal organic compound (aluminum isopropyl alcohol, zinc acetate, titanium acetylacetonate), aziridine-based, multifunctional polycarbodiimide-based crosslinking agent, block type crosslinking agent, and isocyanate-based crosslinking agent. In this embodiment, ethylene glycol dimethacrylate is used as the crosslinking agent.

[0038] Referring to FIG. 1, according to some embodiments of the present application, the metal layer 300 is preferably an aluminum metal layer or a copper metal layer. Specifically, the purity of the metal layer 300 is ≧99.8%. That is, the metal layer 300 in the present application adopts a high purity metal. In one embodiment, the metal layer 300 is an aluminum metal layer, and the purity of the aluminum metal layer is ≧99.8%. High purity aluminum metal has properties such as low deformation resistance, high electrical conductivity and good plasticity. In another embodiment, the metal layer 300 is a copper metal layer, and the purity of the copper metal layer is ≧99.8%. High purity copper metal has good ductility, heat conductivity and electrical conductivity.

[0039] The peel strength between the metal layer 300 and the bridging layer 200 is ≧5 N / m. Exemplarily, the peel strength between the metal layer 300 and the bridging layer 200 is 5 N / m. Since the peel strength between the metal layer 300 and the thin film substrate layer 100 of the composite current collector 10 is high, the phenomenon of the metal layer 300 and the thin film substrate layer 100 falling off is unlikely to occur, and the electrical performance and safety of the battery can be ensured.

[0040] 1, according to some embodiments of the present application, the thickness range of the thin film substrate layer 100 is preferably 1 μm to 25 μm, and the thickness range of the metal layer 300 is preferably 0.5 μm to 2.5 μm. The thickness range of the bridging layer 200 is preferably 0.1 μm to 0.5 μm. Preferably, the thickness range of the bridging layer 200 is 0.2 μm to 0.4 μm.

[0041] In addition, the cross-linked layer 200 is formed by cross-linking the cross-linking agent and the material of the thin film substrate layer 100 with each other, that is, when the cross-linking agent and the thin film substrate layer 100 are cross-linked, the molecules of the cross-linking agent can penetrate into the thin film substrate layer 100, and the cross-linking agent has no thickness outside the thin film substrate layer 100. Therefore, the thickness range of the composite current collector 10 of the present application is 2 μm to 30 μm. EXAMPLES

[0042] The following examples are provided to more specifically describe the contents disclosed in the present invention, and these examples are provided for descriptive purposes only, and it is obvious to those skilled in the art that various modifications and changes may be made within the scope of the contents disclosed in the present invention. Unless otherwise specified, all parts, percentages, and ratios reported in the following examples are based on weight, and all reagents used in the examples are commercially available or can be synthesized by conventional methods, and can be used as is without the need for further processing. All equipment used in the examples is commercially available.

[0043] Referring to FIG. 2, Example 1 of the present application further provides a method for manufacturing a low swelling composite current collector 10, which includes the following steps.

[0044] In step 1, a cross-linking agent was applied to each of two opposing surfaces of the thin film substrate layer 100 .

[0045] Here, in this embodiment, the thickness of the crosslinking agent applied to the thin film base layer 100 was 0.3 μm, and the thickness of the thin film base layer 100 was 6 μm. Ethylene glycol dimethacrylate was used as the crosslinking agent, and polybutylene terephthalate (PET) was used as the thin film base layer 100.

[0046] In step 2, the cross-linking agent and the thin film substrate layer 100 are catalyzed to cross-link the cross-linking agent and the thin film substrate layer 100, forming cross-linked layers 200 on the two opposite surfaces of the thin film substrate layer 100.

[0047] Here, in this embodiment, heating was used as a method for catalyzing the crosslinking agent and the thin film substrate layer 100. The temperature for crosslinking the crosslinking agent and the thin film substrate layer 100 was 120° C. The time for crosslinking the crosslinking agent and the thin film substrate layer 100 was 35 s.

[0048] In step 3, a metal layer 300 was deposited on the surface of the bridging layer 200 to obtain a desired low-swelling composite current collector 10. Here, in this embodiment, the thickness of the metal layer 300 was 1 μm, and the metal layer 300 was a metal aluminum layer.

[0049] Finally, a low-swelling composite current collector 10 of 8 μm was produced. After the production of the low-swelling composite current collector 10 was completed, the low-swelling composite current collector 10 was divided, wound and vacuum-packaged.

[0050] In addition, the cross-linked layer 200 is formed by cross-linking the cross-linking agent and the material of the thin film substrate layer 100 with each other. That is, when the cross-linking agent cross-links with the thin film substrate layer 100, the molecules of the cross-linking agent can penetrate into the thin film substrate layer 100, and the cross-linking agent has no thickness outside the thin film substrate layer 100.

[0051] In another embodiment, the method of catalyzing the crosslinking agent and the thin film substrate layer 100 may be ultraviolet irradiation. The method of catalyzing the crosslinking agent and the thin film substrate layer 100 may be ultraviolet irradiation or heating, thereby increasing the speed of crosslinking between the crosslinking agent and the thin film substrate layer 100. The temperature at which the crosslinking agent and the thin film substrate layer 100 are crosslinked may be any value within a range of 50°C to 200°C. The time for which the crosslinking agent and the thin film substrate layer 100 are crosslinked may be any value within a range of 30 to 50 seconds. Exemplarily, the temperature at which the crosslinking agent and the thin film substrate layer 100 are crosslinked is 150°C. The time for which the crosslinking agent and the thin film substrate layer 100 are crosslinked is 45 seconds.

[0052] [Example 2] The present embodiment is distinguished from embodiment 1 as follows: The thickness of the crosslinking agent applied to the thin film substrate layer 100 was 0.4 μm, and the thickness of the thin film substrate layer 100 was 25 μm. The thickness of the metal layer 300 was 2.5 μm, and the metal layer 300 was a metallic copper layer. The method of catalyzing the crosslinking agent and the thin film substrate layer 100 was ultraviolet irradiation. The temperature for crosslinking the crosslinking agent and the thin film substrate layer 100 was 200° C. The time for crosslinking the crosslinking agent and the thin film substrate layer 100 was 50 s.

[0053] [Example 3] The present embodiment is distinguished from embodiment 1 as follows: The thickness of the crosslinking agent applied to the thin film substrate layer 100 was 0.2 μm, and the thickness of the thin film substrate layer 100 was 1 μm. The thickness of the metal layer 300 was 0.1 μm, and the metal layer 300 was a metal aluminum layer. The method of catalyzing the crosslinking agent and the thin film substrate layer 100 was ultraviolet irradiation. The temperature for crosslinking the crosslinking agent and the thin film substrate layer 100 was 50° C. The time for crosslinking the crosslinking agent and the thin film substrate layer 100 was 30 s.

[0054] [Comparative Example 1] With reference to FIG. 3, the method for producing the composite current collector 10 according to this comparative example included the following steps.

[0055] In step 1, a 6 μm thin film substrate layer 100 and a 99.9% pure metal aluminum layer were selected. Here, polybutylene terephthalate (PET) was used as the thin film substrate layer 100.

[0056] In step 2, the 6 μm thin film substrate layer 100 and the 99.9% pure metallic aluminum layer were placed in a vacuum deposition apparatus, and the metallic aluminum layers were deposited on the two opposite surfaces of the thin film substrate layer 100 to obtain the desired composite current collector 10. Here, in this embodiment, the thickness of the metallic aluminum layer was 1 μm.

[0057] Finally, a composite current collector 10 having a thickness of 8 μm was produced. After the production of the composite current collector 10 was completed, the composite current collector 10 was subjected to the processes of dividing, winding and vacuum packaging.

[0058] [Comparative Example 2] The present comparative example was distinguished from Comparative Example 1 as follows: The thickness of the thin film base layer 100 was 25 μm. The thickness of the metal layer 300 was 2.5 μm, and a metallic copper layer was adopted as the metal layer 300.

[0059] The solubility of the composite current collector 10 of Examples 1 to 3 and Comparative Examples 1 and 2 was measured to obtain the effect data shown in Table 1. The solubility mentioned above means the solubility of the composite current collector 10 in the electrolyte of the battery.

[0060] Table 1 shows the measurement data of the solubility of the composite current collector 10.

[0061] [Table 1]

[0062] As can be seen from the above table, the solubility of the composite current collector 10 of the present invention is lower than that of the composite current collector of the comparative example. The thin film substrate layer 100 of the present invention has low solubility in the battery electrolyte, which greatly reduces the phenomenon of swelling of the thin film substrate layer 100. The chemical bond between the metal layer 300 and the thin film substrate layer 100 cannot be broken, and the peeling force between the metal layer 300 and the thin film substrate layer 100 of the composite current collector 10 is improved, making it difficult for the metal layer 300 and the thin film substrate layer 100 to fall off. This ensures the electrical performance and safety of the battery. In addition, almost no components of the thin film substrate layer 100 dissolve in the battery electrolyte, so the viscosity of the electrolyte does not increase, and thus the internal resistance stability of the battery can be effectively ensured.

[0063] As can be seen from the above table, the solubility of the composite current collector 10 in the battery electrolyte is also related to the thickness of the thin film substrate layer 100 and the thickness of the crosslinking agent applied to the thin film substrate layer 100; the thicker the thin film substrate layer 100, the greater the contact area between the thin film substrate layer 100 and the battery electrolyte, and the thicker the thin film substrate layer 100, the greater the solubility in the battery electrolyte.

[0064] The technical features of the above embodiments can be combined in any way. For the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but as long as there is no contradiction in the combination of these technical features, they should all be considered to be within the scope described in this specification.

[0065] The above examples are merely illustrative of some embodiments of the present invention, and the description is specific and detailed, but it should not be understood as limiting the patent scope of the invention. It should be noted that a person skilled in the art can make some modifications and improvements without departing from the concept of the present invention, and all of these should be considered as belonging to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be according to the appended claims. [Explanation of symbols]

[0066] 10: Composite current collector; 100: Thin film base layer; 200: Crosslinked layer; 300: Metal layer.

Claims

1. The present invention includes a thin film substrate layer (100) having a bridging layer (200) and a metal layer (300) sequentially provided on two opposite surfaces of the thin film substrate layer (100), The crosslinked layer (200) is formed by crosslinking the thin film substrate layer (100) and the surface crosslinking agent applied to the thin film substrate layer (100) through a chemical bonding action. A low swelling composite current collector.

2. The thin film substrate layer (100) comprises at least one of an insulating polymer material, an insulating polymer composite material, a conductive polymer material, and a conductive polymer composite material; 2. The low swelling composite current collector according to claim 1.

3. The thin film substrate layer (100) includes at least one of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polyphenylene sulfide (PPS); 2. The low swelling composite current collector according to claim 1.

4. The metal layer (300) is a metallic aluminum layer or a metallic copper layer; 2. The low swelling composite current collector according to claim 1.

5. The thickness range of the thin film substrate layer (100) is 1 μm to 25 μm, and the thickness range of the metal layer (300) is 0.5 μm to 2.5 μm; 2. The low swelling composite current collector according to claim 1.

6. The thickness range of the crosslinked layer (200) is 0.1 μm to 0.5 μm; 2. The low swelling composite current collector according to claim 1.

7. The thickness range of the crosslinked layer (200) is 0.2 μm to 0.4 μm; 2. The low swelling composite current collector according to claim 1.

8. A method for producing the low-swelling composite current collector according to any one of claims 2 to 7, comprising the steps of: applying the cross-linking agent to two opposite surfaces of the thin film substrate layer (100); catalyzing the crosslinking agent and the thin film substrate layer (100), crosslinking the crosslinking agent and the thin film substrate layer (100), and forming the crosslinked layer (200) on two opposite surfaces of the thin film substrate layer (100); depositing the metal layer (300) on the surface of the bridging layer (200); A method for producing a low swelling composite current collector.

9. The method of catalyzing the crosslinking agent and the thin film substrate layer (100) includes ultraviolet irradiation or heating; The method for producing a low swelling composite current collector according to claim 8 .

10. The temperature for crosslinking the crosslinking agent with the thin film substrate layer (100) is 50°C to 200°C; The method for producing a low swelling composite current collector according to claim 8 .

Images