WO2023216346A1 - Low-swelling composite current collector and preparation method therefor - Google Patents

Abstract

A low-swelling composite current collector, which comprises a thin film substrate layer, wherein the two opposite surfaces of the thin film substrate layer are respectively provided with a crosslinking layer and a metal layer in sequence, and the crosslinking layer is formed by crosslinking a surface crosslinking agent, which coats the thin film substrate layer, with the thin film substrate layer by means of a chemical bond effect. By sequentially arranging the crosslinking layer and the metal layer on each of the two opposite surfaces of the thin film substrate layer, more chemical bonds are formed on the surfaces of the thin film substrate layer, such that the binding force of the metal layers and the thin film substrate layer can be improved, the solubility of the thin film substrate layer in an electrolyte solution of a battery is relatively low, the swelling phenomenon of the thin film substrate layer is mitigated, and the chemical bond between the metal layers and the thin film substrate layer thus cannot be damaged; therefore, the peeling force between the metal layers and the thin film substrate layer is improved, and the metal layers are unlikely to fall off from the thin film substrate layer, thereby guaranteeing the electrical properties, safety and internal resistance stability of the battery.

Description

Low swelling composite current collector and preparation method thereof Technical field

The present invention relates to the technical field of secondary batteries, and in particular to a low-swelling composite current collector and a preparation method thereof.

Background technique

The current composite current collectors are mainly copper current collectors and aluminum current collectors. The copper current collectors or aluminum current collectors are composed of two parts, including a thin film substrate layer in the middle and a thin film substrate layer arranged opposite to each other. metal layers on both surfaces. The thickness requirement of the metal layer is generally about 1 μm. The method of preparing the composite current collector is through an evaporation process. However, since the film base material layer is mostly made of polymer materials such as polyethylene terephthalate (PET), These polymer materials contain a large number of ester groups. After the electrolyte in the battery comes into contact with the polymer material, the ester group in the polymer material meets the ester group in the electrolyte and dissolves, causing the thin film substrate layer to easily appear during long-term use of the battery. The swelling phenomenon destroys the chemical bond between the metal layer and the film substrate layer, resulting in the continuous deterioration of the peeling force between the metal layer and the film substrate layer of the composite current collector, and the metal layer and the film substrate layer are prone to peeling off. phenomenon, which in turn affects the positive and negative electrode interfaces inside the battery, resulting in poor electrical performance of the battery and also affecting the safety of the battery. When the polymer material dissolves and enters the electrolyte, it will also increase the viscosity of the electrolyte, which will increase the obstruction of ion transmission and lead to an increase in the internal resistance of the battery in the later stage of the battery.

Contents of the invention

Based on this, it is necessary to provide a method that can make the solubility of the film base material layer in the electrolyte of the battery lower, so that the swelling phenomenon of the film base material layer can be greatly reduced, and the gap between the metal layer and the film base material layer can be improved. The peeling force makes the metal layer and the film substrate layer less likely to fall off, thereby ensuring the low-swelling composite current collector and its preparation method of the battery's electrical performance, safety and internal resistance stability.

A low-swelling composite current collector including:

Film base material layer, the two surfaces of the film base material layer arranged opposite to each other are respectively provided with a cross-linked layer and a metal layer, wherein

The cross-linked layer is formed by cross-linking the surface cross-linking agent coated on the film base material layer with the film base material layer through chemical bonds.

The cross-linked layer and the metal layer are sequentially arranged on two opposite surfaces of the film base material layer, and the cross-linked layer is cross-linked with the film base material layer through chemical bonds through the surface cross-linking agent coated on the film base material layer. It is formed to form more chemical bonds on the surface of the film base material layer, which can not only improve the binding force between the metal layer and the film base material layer, but also make the solubility of the film base material layer in the electrolyte of the battery lower, thereby The swelling phenomenon of the film base material layer is greatly reduced, and the chemical bond between the metal layer and the film base material layer cannot be destroyed, thereby improving the peeling force between the metal layer and the film base material layer, making the metal layer and the film base material layer It is not easy to fall off, thus ensuring the electrical performance and safety of the battery. Since almost no components of the film substrate layer are dissolved into the electrolyte of the battery, the viscosity of the electrolyte will not increase, thus effectively ensuring the stability of the internal resistance of the battery. .

In one embodiment, the film base material layer includes at least one of an insulating polymer material, an insulating polymer composite material, a conductive polymer material, and a conductive polymer composite material.

Among them, insulating polymer materials include polyamide (PA), polyterephthalate, polyimide (PI), polyethylene (PE), polypropylene (PP), polystyrene (PPE), polychloride Ethylene (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) ), at least one of polyethylene glycol (PEG), cellulose, starch, protein, their derivatives, their cross-linked products and their copolymers.

Insulating polymer composite materials are composite materials formed of insulating polymer materials and inorganic materials. The inorganic material may be at least one of ceramic materials, glass materials, and ceramic composite materials.

The conductive polymer material uses at least one of doped polysulfide nitride and doped polyacetylene.

Conductive polymer composite materials are composite materials formed of insulating polymer materials and conductive materials.

In one embodiment, the film base material layer includes at least one of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polyphenylene sulfide (PPS). kind.

In one embodiment, the metal layer is a metal aluminum layer or a metal copper layer.

In one embodiment, the thickness of the film base material layer ranges from 1 μm to 25 μm, and the thickness of the metal layer ranges from 0.5 μm to 2.5 μm.

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

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

This application also provides a method for preparing the low-swelling composite current collector as mentioned above, which includes the following steps:

Apply the cross-linking agent on two opposite surfaces of the film base material layer;

The cross-linking agent and the film base material layer are catalyzed to cross-link the cross-linking agent and the film base material layer, and the two surfaces of the film base material layer arranged opposite to each other are formed. The cross-linked layer;

The metal layer is evaporated on the surface of the cross-linked layer.

In one embodiment, the method of catalyzing the cross-linking agent and the film substrate layer includes ultraviolet light irradiation or heating.

In one embodiment, the temperature at which the cross-linking agent and the film substrate layer are cross-linked is 50°C-200°C.

In the above solution, a cross-linked layer and a metal layer are sequentially provided on two opposite surfaces of the film base material layer, and the cross-linked layer is formed by a surface cross-linking agent coated on the film base material layer through chemical bonds with the film base material. The layers are cross-linked with each other to form more chemical bonds on the surface of the film base material layer, which can not only improve the binding force between the metal layer and the film base material layer, but also improve the solubility of the film base material layer in the electrolyte of the battery. Lower, thus greatly reducing the swelling phenomenon of the film base material layer, unable to destroy the chemical bond between the metal layer and the film base material layer, thereby improving the peeling force between the metal layer and the film base material layer, making the metal layer and the film base material layer The film base material layer is not easy to fall off, thereby ensuring the electrical performance and safety of the battery. And because almost no components of the film base material layer dissolve into the battery's electrolyte, the viscosity of the electrolyte will not increase, thus effectively ensuring the battery's performance. Internal resistance stability; by catalyzing the cross-linking agent and the film base material layer using ultraviolet light irradiation or heating, the cross-linking speed of the cross-linking agent and the film base material layer can be increased.

Description of the drawings

The drawings forming a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without exerting creative efforts.

Figure 1 is a schematic structural diagram of a composite current collector shown in an embodiment of the present invention;

Figure 2 is a schematic flow chart of the steps of a method for preparing a composite current collector according to an embodiment of the present invention;

FIG. 3 is a schematic flowchart of the steps of a preparation method of a composite current collector shown in a pair of proportions of the present invention.

Explanation of reference signs

10. Composite current collector; 100. Thin film substrate layer; 200. Cross-linked layer; 300. Metal layer.

Detailed ways

In order to make the above objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, the present invention can be implemented in many other ways different from those described here. Those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " "Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inside", "Outside", "Clockwise", "Counterclockwise", "Axis" The orientations or positional relationships indicated by "radial direction", "circumferential direction", etc. are based on the orientations or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply the device or device referred to. Elements must have a specific orientation, be constructed and operate in a specific orientation and therefore are not to be construed as limitations of the invention.

In addition, the terms “first” and “second” are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Therefore, features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

In the present invention, unless otherwise clearly stated and limited, the terms "installation", "connection", "connection", "fixing" and other terms should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection. , or integrated into one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be an internal connection between two elements or an interactive relationship between two elements, unless otherwise specified restrictions. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

In the present invention, unless otherwise expressly stated and limited, a first feature being "on" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. touch. Furthermore, the terms "above", "above" and "above" the first feature is above the second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "below" and "beneath" the first feature to the second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature has a smaller horizontal height than the second feature.

It should be noted that when an element is referred to as being "mounted" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is said to be "connected" to another element, it can be directly connected to the other element or there may also be intervening elements present. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation manner.

Please refer to Figure 1. One embodiment of the present invention provides a low-swelling composite current collector 10, which includes a film base material layer 100, a cross-linking agent and a metal layer 300. The film base material layer 100 is disposed in the middle. The cross-linked layer 200 and the metal layer 300 are respectively arranged on the two opposite surfaces of the layer 100. Specifically, the puncture strength of the composite current collector 10 is ≥50gf, the MD tensile strength is ≥150MPa, the TD tensile strength is ≥150MPa, the MD elongation is ≥10%, and the TD elongation is ≥10%. For example, the composite current collector 10 has a puncture strength of 70 gf, an MD tensile strength of 180 MPa, and a TD tensile strength of 180 MPa. The MD elongation is 20% and the TD elongation is 20%. It should be noted that: MD (Machine Direction, machine direction) refers to the longitudinal direction, and TD (Transverse Direction, perpendicular to the machine direction) refers to the transverse direction.

The cross-linked layer 200 is formed by cross-linking the surface cross-linking agent coated on the film base material layer 100 with the film base material layer 100 through chemical bonds. Specifically, the film base material layer 100 has a first surface and a second surface that are oppositely arranged in the thickness direction thereof. The cross-linking agent is coated on the two opposite surfaces of the film base material layer 100 through chemical bonds. This means that the cross-linking agent is coated on the first surface and the second surface of the film base material layer 100 respectively, and is combined with the film base material layer 100 . The materials of the material layer 100 are cross-linked with each other.

The cross-linked layer 200 and the metal layer 300 are sequentially disposed on two opposite surfaces of the film base material layer 100, and the cross-linked layer 200 is formed from the surface cross-linking agent coated on the film base material layer 100 through chemical bonds with the film base. The material layers 100 are cross-linked with each other to form more chemical bonds on the surface of the film base material layer 100, which can improve the bonding force between the metal layer 300 and the film base material layer 100, and also enable the film base material layer 100 to The solubility of the electrolyte of the battery is low, which greatly reduces the swelling of the film base material layer 100 and cannot destroy the chemical bond between the metal layer 300 and the film base material layer 100, thereby improving the relationship between the metal layer 300 and the film base material layer. The peeling force between the metal layer 300 and the film base material layer 100 makes it difficult for the metal layer 300 and the film base material layer 100 to fall off, thereby ensuring the electrical performance and safety of the battery, and because almost no components of the metal layer 300 and the film base material layer 100 are dissolved into the battery In the electrolyte, the viscosity of the electrolyte will not increase, which can effectively ensure the stability of the internal resistance of the battery.

Referring to Figure 1, according to some embodiments of the present application, optionally, the film base material layer 100 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 puncture strength of the film base material layer 100 is ≥100gf, the MD tensile strength is ≥200MPa, and the TD tensile strength is ≥200MPa. MD elongation ≥30%, TD elongation ≥30%. For example, the film base material layer 100 has a puncture strength of 120 gf, an MD tensile strength of 250 MPa, and a TD tensile strength of 250 MPa. The MD elongation is 40% and the TD elongation is 40%.

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

The above-mentioned insulating polymer composite material may be a composite material formed of an insulating polymer material and an inorganic material. The inorganic material may be at least one of ceramic materials, glass materials, and ceramic composite materials.

The above-mentioned conductive polymer material may be at least one of doped polysulfide nitride and doped polyacetylene.

The above-mentioned 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 conductive carbon materials, metal materials, and composite conductive materials. More specifically, the conductive carbon material is selected from at least one of carbon black, carbon nanotubes, graphite, acetylene black, and graphene. The metal material is selected from at least one of metal nickel, metal iron, metal copper, metal aluminum or alloys of the above metals. The composite conductive material is selected from at least one of metal nickel-coated graphite powder and metal nickel-coated carbon fiber.

Please refer to Figure 1. According to some embodiments of the present application, optionally, the cross-linking agent may be a polyisocyanate (JQ-1, JQ-1E, JQ-2E, JQ-3E, JQ-4, JQ-5, JQ -6. PAPI, emulsifiable MDI, tetraisocyanate), polyamines (propylenediamine, MOCA), polyols (polyethylene glycol, polypropylene glycol, trimethylolpropane, trimethylolethane), Glycidyl ether (polypropylene glycol glycidyl ether), inorganic substances (zinc oxide, aluminum chloride, aluminum sulfate, sulfur, boric acid, borax, chromium nitrate), organic substances (styrene, α-methylstyrene, acrylonitrile, acrylic acid , methacrylic acid, glyoxal, aziridine), organic silicones (ethyl orthosilicate, methyl orthosilicate, trimethoxysilane), benzenesulfonic acids (p-toluenesulfonic acid, p-toluenesulfonyl chloride ), acrylates (1,4-butanediol diacrylate, ethylene glycol dimethacrylate, TAC, butyl acrylate, HEA, HPA, HEMA, HPMA, MMA), organic peroxides (peroxide Dicumyl oxide, bis-2,4-dichlorobenzoyl peroxide), metal organic compounds (aluminum isopropoxide, zinc acetate, titanium acetylacetonate), aziridines, multifunctional polycarbodiimides At least one of a cross-linking agent, a blocked cross-linking agent, and an isocyanate cross-linking agent. In this embodiment, ethylene glycol dimethacrylate is used as the cross-linking agent.

Referring to Figure 1, according to some embodiments of the present application, optionally, the metal layer 300 is a metal aluminum layer or a metal copper layer. Specifically, the purity of metal layer 300 is ≥99.8%. In other words, the metal layer 300 in this application uses high-purity metal. In one embodiment, the metal layer 300 is a metal aluminum layer, and the purity of the metal aluminum layer is ≥99.8%. High-purity metallic aluminum has low deformation resistance, high electrical conductivity and good plasticity. In another embodiment, the metal layer 300 is a metal copper layer, and the purity of the metal copper layer is ≥99.8%. High-purity metallic copper has good ductility, heat transfer and electrical conductivity.

The peeling force between the metal layer 300 and the cross-linked layer 200 is ≥5N/m. For example, the peeling force between the metal layer 300 and the cross-linked layer 200 is 5 N/m. The peeling force between the metal layer 300 and the film substrate layer 100 of the composite current collector 10 is relatively high, which can prevent the metal layer 300 and the film substrate layer 100 from falling off easily, thereby ensuring the electrical performance and safety of the battery.

Referring to Figure 1, according to some embodiments of the present application, optionally, the thickness of the film substrate layer 100 ranges from 1 μm to 25 μm, and the thickness of the metal layer 300 ranges from 0.5 μm to 2.5 μm. The thickness of the cross-linked layer 200 ranges from 0.1 μm to 0.5 μm. Preferably, the thickness of the cross-linked layer 200 ranges from 0.2 μm to 0.4 μm.

It should be understood that the cross-linked layer 200 is formed by cross-linking the cross-linking agent and the material of the film base material layer 100. That is to say, when the cross-linking agent and the film base material layer 100 are cross-linked, the molecules of the cross-linking agent The cross-linking agent can penetrate into the film base material layer 100 , while the cross-linking agent has no thickness outside the film base material layer 100 . Therefore, the thickness of the composite current collector 10 of the present application ranges from 2 μm to 30 μm.

Example:

The following examples more specifically describe the present disclosure. These examples are for illustrative purposes only, since it will be apparent to those skilled in the art that various modifications and changes can be made within the scope of the present disclosure. Unless otherwise stated, 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 synthesized according to conventional methods, and can be directly were used without further processing and the equipment used in the examples is commercially available.

Please refer to Figure 2. Embodiment 1 of the present application also provides a method for preparing a low-swelling composite current collector 10, which includes the following steps:

Step 1: Coat cross-linking agent on two opposite surfaces of the film base material layer 100 respectively.

In this embodiment, the thickness of the cross-linking agent coated on the film base material layer 100 is 0.3 μm, and the thickness of the film base material layer 100 is 6 μm. The cross-linking agent is ethylene glycol dimethacrylate, and the film base layer 100 is polybutylene terephthalate (PET).

Step 2: catalyze the cross-linking agent and the film base material layer 100 to cross-link the cross-linking agent and the film base material layer 100, and form cross-linked layers 200 on two opposite surfaces of the film base material layer 100.

In this embodiment, heating is used to catalyze the cross-linking agent and the film base material layer 100 . The temperature at which the cross-linking agent and the film base material layer 100 are cross-linked is 120°C. The cross-linking time of the cross-linking agent and the film base material layer 100 is 35 seconds.

Step 3: Evaporate the metal layer 300 on the surface of the cross-linked layer 200 to obtain the required low-swelling composite current collector 10. In this embodiment, the thickness of the metal layer 300 is 1 μm, and the metal layer 300 is a metal aluminum layer.

Finally, a low-swelling composite current collector 10 of 8 μm was prepared. After the preparation of the low-swelling composite current collector 10 is completed, the low-swelling composite current collector 10 is cut, rolled, and vacuum packed.

It should be noted that the cross-linked layer 200 is formed by cross-linking the cross-linking agent and the material of the film base material layer 100. That is to say, when the cross-linking agent and the film base material layer 100 are cross-linked, the molecules of the cross-linking agent The cross-linking agent can penetrate into the film base material layer 100 , while the cross-linking agent has no thickness outside the film base material layer 100 .

In other embodiments, ultraviolet light irradiation may be used to catalyze the cross-linking agent and the film base material layer 100 . By using ultraviolet light irradiation or heating to catalyze the cross-linking agent and the film base material layer 100, the cross-linking speed of the cross-linking agent and the film base material layer 100 can be increased. The temperature at which the cross-linking agent and the film base material layer 100 are cross-linked is any value between 50°C and 200°C. The time for the cross-linking agent and the film base material layer 100 to cross-link is any value from 30 to 50 seconds. For example, the temperature at which the cross-linking agent and the film base material layer 100 are cross-linked is 150°C. The cross-linking time of the cross-linking agent and the film base material layer 100 is 45 seconds.

Example 2

The difference between this embodiment and Embodiment 1 is that the thickness of the cross-linking agent coated on the film base material layer 100 is 0.4 μm, and the thickness of the film base material layer 100 is 25 μm. The thickness of the metal layer 300 is 2.5 μm, and the metal layer 300 is a metal copper layer. The cross-linking agent and the film base material layer 100 are catalyzed by ultraviolet light irradiation. The temperature at which the cross-linking agent and the film base material layer 100 are cross-linked is 200°C. The cross-linking time of the cross-linking agent and the film base material layer 100 is 50 seconds.

Example 3

The difference between this embodiment and Embodiment 1 is that the thickness of the cross-linking agent coated on the film base material layer 100 is 0.2 μm, and the thickness of the film base material layer 100 is 1 μm. The thickness of the metal layer 300 is 0.1 μm, and the metal layer 300 is a metal aluminum layer. The cross-linking agent and the film base material layer 100 are catalyzed by ultraviolet light irradiation. The temperature at which the cross-linking agent and the film base material layer 100 are cross-linked is 50°C. The cross-linking time for the cross-linking agent and the film base material layer 100 is 30 seconds.

Comparative example 1

Please refer to Figure 3. The preparation method of the composite current collector 10 provided in this comparative example includes the following steps:

Step 1: Select a 6 μm film substrate layer 100 and a 99.9% purity metal aluminum layer. Among them, the film base material layer 100 is made of polybutylene terephthalate (PET).

Step 2: Put the 6 μm thin film base material layer 100 and the 99.9% purity metal aluminum layer into the vacuum coating equipment respectively, and evaporate the metal aluminum layers on the two opposite surfaces of the thin film base material layer 100 to obtain the result. The required composite current collector 10. In this embodiment, the thickness of the metallic aluminum layer is 1 μm.

Finally, an 8 μm composite current collector 10 was produced. After the preparation of the composite current collector 10 is completed, the composite current collector 10 is cut, rolled, and vacuum packed.

Comparative example 2

The difference between this comparative example and Comparative Example 1 is that the thickness of the film base material layer 100 is 25 μm. The thickness of the metal layer 300 is 2.5 μm, and the metal layer 300 is a metal copper layer.

The solubility of the composite current collector 10 of Example 1-3 and Comparative Example 1-2 was tested, and the effect data as shown in Table 1 was obtained. It should be understood that the above solubility refers to the solubility of the composite current collector 10 in the electrolyte of the battery.

Table 1 shows the solubility test data of composite current collector 10.

plan	Solubility%
Example 1	0.1
Example 2	0.12
Example 3	0.08
Comparative example 1	3
Comparative example 2	5

Table 1

It can be seen from the above table that 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. It can be seen that the solubility of the thin film base material layer 100 of the present invention in the electrolyte of the battery is low, causing the thin film base material layer 100 to appear The swelling phenomenon is greatly reduced, so that the chemical bond between the metal layer 300 and the film substrate layer 100 cannot be destroyed, so as to improve the peeling force between the metal layer 300 of the composite current collector 10 and the film substrate layer 100, so that the metal layer 300 The film base material layer 100 is not easy to fall off, thereby ensuring the electrical performance and safety of the battery. Moreover, since almost no components of the film base material layer 100 are dissolved into the electrolyte of the battery, the viscosity of the electrolyte will not increase, thereby preventing the electrolyte from increasing. It can effectively ensure the internal resistance stability of the battery.

It can be concluded from the above table that the solubility of the composite current collector 10 in the electrolyte of the battery is also related to the thickness of the film base material layer 100 and the thickness of the cross-linking agent coated on the film base material layer 100. The thickness of the film base material layer 100 The thicker the film base material layer 100 is, the greater the contact area between the film base material layer 100 and the electrolyte solution of the battery. The thicker film base material layer 100 has a greater solubility in the battery electrolyte solution.

The technical features of the above-described embodiments can be combined in any way. To simplify the description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, All should be considered to be within the scope of this manual.

The above-mentioned embodiments only express several implementation modes of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the scope of protection of the patent of the present invention should be determined by the appended claims.

Claims (10)

1. A low-swelling composite current collector, characterized by including:

   Film base material layer (100), the two surfaces of the film base material layer (100) arranged opposite to each other are respectively provided with a cross-linked layer (200) and a metal layer (300), wherein

   The cross-linked layer (200) is formed by cross-linking the surface cross-linking agent coated on the film base material layer (100) with the film base material layer (100) through chemical bonds.
2. The low-swelling composite current collector according to claim 1, characterized in that the film base material layer (100) includes an insulating polymer material, an insulating polymer composite material, a conductive polymer material, and a conductive polymer composite material. of at least one.
3. The low-swelling composite current collector according to claim 1, wherein the film base material layer (100) includes polyethylene (PE), polypropylene (PP), polyethylene terephthalate ( At least one of PET) and polyphenylene sulfide (PPS).
4. The low-swelling composite current collector according to claim 1, wherein the metal layer (300) is a metal aluminum layer or a metal copper layer.
5. The low-swelling composite current collector according to claim 1, characterized in that the thickness of the film base material layer (100) ranges from 1 μm to 25 μm, and the thickness of the metal layer (300) ranges from 0.5 μm to 2.5 μm. μm.
6. The low-swelling composite current collector according to claim 1, wherein the thickness of the cross-linked layer (200) ranges from 0.1 μm to 0.5 μm.
7. The low-swelling composite current collector according to claim 1, wherein the thickness of the cross-linked layer (200) ranges from 0.2 μm to 0.4 μm.
8. A method for preparing a low-swelling composite current collector according to any one of claims 2 to 7, characterized in that it includes the following steps:

   The cross-linking agent is respectively coated on two opposite surfaces of the film base material layer (100);

   The cross-linking agent and the film base material layer (100) are catalyzed to cross-link the cross-linking agent and the film base material layer (100), and the film base material layer (100) is Two surfaces arranged oppositely form the cross-linked layer (200);

   The metal layer (300) is evaporated on the surface of the cross-linked layer (200).
9. The method for preparing a low-swelling composite current collector according to claim 8, characterized in that the method of catalyzing the cross-linking agent and the film base material layer (100) includes ultraviolet light irradiation or heating.
10. The method for preparing a low-swelling composite current collector according to claim 8, characterized in that the cross-linking temperature of the cross-linking agent and the film base material layer (100) is 50°C-200°C.

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