Light composite current collector

Abstract

The utility model provides a light composite current collector which comprises a supporting layer, the upper surface and the lower surface of the supporting layer are respectively provided with a metal coating, the metal coatings are formed on the supporting layer in a one-step forming mode, and the thickness of each metal coating ranges from 500 nm to 1500 nm. According to the light composite current collector, the metal coatings are formed on the upper surface and the lower surface of the supporting layer in a one-time forming mode, the mutual binding force of metal particles can be improved through the structure, the problem that the metal layers are prone to falling off due to multiple times of forming is solved, the metal coatings are appropriate in thickness, and the service life of the metal coatings is prolonged. The light weight of the composite current collector is maintained, good conductivity can be provided at the same time, and the battery performance can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium batteries, in particular to a lightweight composite current collector. Background Art

[0002] The composite current collector is a new type of current collector material composed of polymer materials and metals. It is used to gather current in batteries. Its structure is a "sandwich" structure with a plastic film layer in the middle and two surfaces in the thickness direction of the plastic film layer. There are metal layers on the two surfaces. Compared with traditional pure metal current collectors, composite current collectors have advantages in safety and potential cost-effectiveness.

[0003] However, the surface microstructure of the metal layer of the composite current collector currently produced by manufacturers is relatively smooth, and the metal particles do not have enough bonding force with each other, which causes the plated metal to easily fall off, thus affecting battery performance. Utility Model Content

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a lightweight composite current collector, aiming to solve the problem that the metal layer in the composite current collector is easy to fall off and improve the conductive performance of the composite current collector.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] The utility model provides a lightweight composite current collector, which comprises a support layer. The upper and lower surfaces of the support layer are both provided with a metal coating, the metal coating is formed on the support layer in one step, and the thickness of the metal coating is 500nm-1500nm.

[0007] In one embodiment, the thickness of the metal coating is 1 um.

[0008] In one embodiment, the particles of the metal coating are columnar particles formed in one step, and at least part of the columnar particles are inclined particles that are not perpendicular to the support layer.

[0009] In one embodiment, the angle between the inclined particles in the metal coating and the support layer is greater than 45° and less than 90°.

[0010] In one embodiment, the content of the inclined particles in the metal coating is 80%-90%.

[0011] In one embodiment, the material of the metal coating is one or more of aluminum metal, nickel metal, titanium metal, copper metal, nickel alloy, copper alloy, aluminum alloy, and titanium alloy.

[0012] In one embodiment, the diameter of the inclined particles is greater than 50 nm and less than or equal to 150 nm.

[0013] In one embodiment, the average gap between particles of the metal coating is greater than 0 nm and less than or equal to 10 nm.

[0014] In one embodiment, the upper and lower surfaces of the support layer have a structure of low points and high points, wherein the low points are areas below the plane where the support layer is located, and the high points are areas above the plane where the support layer is located, and the particles of the metal coating are located within the low points and the high points, and multiple high points surround the low points.

[0015] In one embodiment, an anti-corrosion layer is further provided between the metal coating and the support layer, and the particle microstructure of the anti-corrosion layer is circular, elliptical or other polygonal structure.

[0016] Compared with the prior art, the utility model provides a lightweight composite current collector, including a support layer, the upper and lower surfaces of the support layer are both provided with a metal coating, the metal coating is formed on the support layer in one molding, and the thickness of the metal coating is 500nm-1500nm. The lightweight composite current collector of the utility model forms a metal coating on the upper and lower surfaces of the support layer by one molding. Such a structure can improve the mutual binding force of metal particles and prevent the problem of easy detachment of the metal layer caused by multiple moldings. The metal coating adopts a suitable thickness, which can provide better conductivity while maintaining the lightweight of the composite current collector, which is conducive to improving battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained according to the structures shown in these drawings without creative work. In the drawings:

[0018] Figure 1 This is a schematic diagram of the structure of a lightweight composite current collector in an embodiment of the utility model;

[0019] Figure 2 An electron microscope image of the metal coating of the lightweight composite current collector in the embodiment of the utility model;

[0020] Figure 3 This is a schematic diagram of an arrangement of evaporation boats in a vacuum chamber according to an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of another arrangement of evaporation boats in a vacuum chamber according to an embodiment of the present invention;

[0022] Figure 5Another electron microscope image of the metal coating of the lightweight composite current collector in the embodiment of the utility model;

[0023] Figure 6 The present invention is a flow chart of a method for preparing a lightweight composite current collector in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and beneficial effects to be solved by the embodiments of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it can be directly on the other component or indirectly on the other component. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, connection can be used for fixing or for circuit connection.

[0026] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the utility model.

[0027] 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 number of indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present utility model, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0028] The utility model provides a lightweight composite current collector, such as Figure 1As shown, the lightweight composite current collector includes a support layer 100, and the upper and lower surfaces of the support layer 100 are provided with a metal coating 200, and the metal coating 200 is formed on the support layer 100 by vacuum evaporation. Of course, in other embodiments, the metal coating 200 can also be formed on the upper and lower surfaces of the support layer 100 by other methods. For example, some conductive particles can be arranged inside the support layer 100 to make the support layer 100 conductive, and then the metal coating 200 is formed on the support layer 100 by electroplating, or the metal coating 200 is plated on the support layer 100 by chemical plating, etc., so that the one-time forming structure can improve the mutual bonding force of the metal particles and prevent the problem of the metal layer being easily detached due to multiple forming. At the same time, the thickness of the metal coating 200 on the upper surface of the support layer 100 and the metal coating 200 on the lower surface are 500nm-1500nm respectively, and the thickness of the metal coating 200 on the upper surface and the thickness of the metal coating 200 on the lower surface can be the same or different, and can be flexibly adjusted based on product requirements. By controlling the thickness of the metal coating 200 formed at one time on the upper and lower surfaces, the mass of the lightweight composite current collector can be reduced, which helps to improve the mass energy density of the battery, which is crucial for manufacturing lightweight and energy-efficient battery products and has a positive impact on improving the overall performance of the battery.

[0029] Specifically, the support layer 100 is a film made of at least one material selected from polyamide, polyterephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, poly(p-phenylene terephthalamide), polypropylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, and polycarbonate. Using a film made of a polymer material as the support layer 100 is beneficial to improving the safety and lightness of the current collector and improving the energy density of the battery.

[0030] Preferably, the thickness of the metal coating 200 is 1 um, which can provide good conductivity while maintaining the light weight of the composite current collector. The thicker the thickness, the worse the density, which will affect the conductive effect. By using a metal coating 200 of appropriate thickness, the light weight of the composite current collector can be improved while improving the binding force of the metal particles.

[0031] Specifically, the material of the metal coating 200 is one or more of aluminum metal, nickel metal, titanium metal, copper metal, nickel alloy, copper alloy, aluminum alloy, and titanium alloy. Among them, the material of the metal coating 200 on the upper surface and the metal coating 200 on the lower surface can be the same, for example, the material of the metal coating 200 on the upper surface and the material of the metal coating 200 on the lower surface are both copper metal; the material of the metal coating 200 on the upper surface and the metal coating 200 on the lower surface can also be different, for example: the material of the metal coating 200 on the upper surface is copper metal, and the material of the metal coating 200 on the lower surface is nickel alloy, which can be flexibly selected according to actual needs. The metal coating 200 formed in one step can better play the role of converging current, is not easy to fall off, and improves the conductive performance of the lightweight composite current collector.

[0032] Preferably, in the lightweight composite current collector of the present invention, the particles of the metal coating 200 are columnar particles formed in one step, and at least part of the columnar particles are inclined particles that are not perpendicular to the support layer 100. Figure 2 As shown, it is the microstructure of the metal coating 200 of the utility model. The particles of the metal coating 200 are columnar particles, which grow on the support layer 100 in one-time molding, and the columnar particles are not formed vertically on the support layer 100. At least part of the columnar particles are inclined particles that form a certain angle with the support layer 100. In this way, compared with the particles of the metal coating 200 being vertically arranged on the support layer 100, when used in a battery, the electrolyte will not easily contact the support layer 100 through the gaps between the particles of the metal coating 200, thereby improving the life of the composite current collector of the utility model. In the utility model, PP film is preferably used as the support layer 100 because it is more acid-resistant and alkali-resistant, and can greatly improve the service life of the composite current collector of the utility model together with the metal coating 200 structure of the utility model. The PP film is preferably 3um-8um, which can reduce the mass of the current collector of the utility model and improve the energy density of the battery.

[0033] Furthermore, in the lightweight composite current collector of the utility model, the angle between the inclined particles in the metal coating 200 and the support layer 100 is greater than 45° and less than 90°. When the metal coating 200 is formed on the support layer 100 in one-step molding, taking the vacuum evaporation method as an example, the inclination angle of the inclined particles can be achieved by controlling the speed of the support layer 100 in the vacuum chamber and the number of evaporation boats arranged in the vacuum chamber. For example, in production, the speed of the support layer 100 in the vacuum chamber is controlled to be 5-7m / min. In the vacuum chamber, Figure 3 As shown, there are two evaporation areas, and the total number of evaporation boats in each evaporation area is 10-16, which are arranged in two rows, 5-8 in each row, and arranged alternately on the left and right sides; or Figure 4As shown, the evaporation boats can also be arranged alternately up and down, wherein the shadowed ones are the lower evaporation boats, and the unshadowed ones are the upper evaporation boats, that is, in the same vertical plane, there are 5-8 in one row on the upper side and 5-8 in one row on the lower side. During the vacuum evaporation process, the metal melts into liquid in the evaporation boat, forms metal vapor and begins to volatilize, and the atoms in the vapor are rapidly transmitted to the upper support layer 100 in a linear motion without collision, and the gaseous particles reaching the surface of the support layer 100 are attached to the surface of the support layer 100 for deposition and growth. The deposition position and angle of the metal particles on the support layer 100 are related to the starting position of the metal particles (i.e., the arrangement position and number of the evaporation boats in the vacuum chamber), and are also related to the moving speed of the support layer 100 itself (i.e., the speed of the support layer 100 in the vacuum chamber). By controlling the speed of the support layer 100 in the vacuum chamber and the number and distribution of the evaporation boats during production, columnar particles with an inclination angle of 45°-90° with the support layer 100 can be obtained, thereby improving the life of the composite current collector. This method is specifically implemented in a vacuum evaporation device of suspended plating. Suspended plating means that the support layer 100 passes through the upper part of the evaporation boat and then the support layer 100 is cooled, rather than being cooled when passing through the upper part of the evaporation boat. Suspended plating can make the coating more uniform, the cooling effect better, and the coating quality higher.

[0034] Furthermore, in the lightweight composite current collector of the utility model, the content of inclined particles in the metal coating 200 is 80%-90%, and the remaining columnar particles can be vertical particles perpendicular to the support layer 100. The metal coating 200 has both inclined particles and vertical particles. The presence of vertical particles can release the stress formed by the metal coating 200 of the inclined particles. The stresses offset each other, which can greatly reduce the curling and warping of the plated film, affecting the adhesion of the current collector and the subsequent processing performance of the current collector coating process. Specifically, the content of inclined particles and vertical particles can be adjusted by multiple coatings in a vacuum chamber. For example, in a vacuum chamber of suspension plating, a small amount or a majority of inclined columnar particles are first formed on the support layer 100 by a fast travel speed and a small number of evaporation boats, and then a slow travel speed, more evaporation boats or fewer evaporation boats are used to form vertical particles. For example, when forming 80%-90% columnar inclined particles, a film speed of 2-3m / min can be first used, with 2-3 evaporation boats in a row, 2 rows in total, cross-arranged, and 4-6 in total; then use suspended vacuum evaporation, and then use a travel speed of 5-7m / min, with 4-6 evaporation boats in a row, 2 rows in total, and relatively arranged evaporation boats for coating, so as to form a metal coating 200 with both inclined particles and vertical particles on the support layer 100, thereby improving the performance of the composite current collector.

[0035] Furthermore, in the lightweight composite current collector of the utility model, the diameter of the inclined particles with a certain angle is greater than 50nm and less than or equal to 150nm. The composite current collector with such metal coating 200 particles can be formed more quickly, reducing the overall cost of the composite current collector, and is not easy to fall off.

[0036] Furthermore, in the lightweight composite current collector of the present invention, the average gap between the particles of the metal coating 200 is greater than 0 nm and less than or equal to 10 nm, so that the coating of the composite current collector can have better compactness. Figure 1 As shown, when used in a battery, it is difficult for the electrolyte to penetrate into and react with the support layer, thereby increasing the service life of the battery.

[0037] Preferably, the lightweight composite current collector of the utility model further includes an insulating coating, which is disposed between the metal coating 200 and the support layer 100. The insulating coating may be a metal oxide coating such as aluminum oxide, silicon oxide, titanium oxide, etc. In this embodiment, the insulating coating is disposed on both the upper and lower surfaces of the support layer 100, and the metal coating 200 is disposed on the surface of the insulating coating. The insulating coating between the metal coating 200 and the support layer 100 can effectively prevent the metal connection between the upper and lower surfaces of the current collector, prevent danger, and improve the safety of the product.

[0038] Furthermore, the thermal shrinkage rate of the insulating coating is greater than or equal to the thermal shrinkage rate of the support layer 100, and greater than the thermal shrinkage rate of the metal coating 200. In the lightweight composite current collector of this embodiment, an insulating coating with a higher thermal shrinkage rate is arranged between the support layer 100 and the metal coating 200, and the thermal shrinkage rate of the insulating coating is greater than or equal to the thermal shrinkage rate of the support layer 100, and greater than the thermal shrinkage rate of the metal coating 200. In this way, when the lightweight composite current collector of the utility model is pierced by a sharp object and a short circuit occurs, and the local heat is high, the support layer 100 shrinks, and the insulating coating shrinks together, while the thermal shrinkage rate of the metal coating 200 is smaller at this time, so it shrinks slowly, and the thermal shrinkage rate of the insulating coating is higher, so that the insulating coating will wrap up the pierced position to prevent the metal connection between the upper and lower surfaces of the current collector, and can effectively form a point resistance to prevent danger, improve the flame retardant effect of the lightweight composite current collector, and make the battery using the lightweight composite current collector safer.

[0039] Preferably, in the lightweight composite current collector of the utility model, the upper and lower surfaces of the support layer 100 have a structure of low points and high points, wherein the low points are areas below the plane where the support layer 100 is located, and the high points are areas above the plane where the support layer 100 is located, and the particles of the metal coating 200 are located in the low points and the high points, and multiple high points surround the low points. Figure 5As shown at the bottom, the surface of the support layer 100 in the composite current collector of the utility model is not smooth. Before preparing the metal coating 200 on the upper and lower surfaces of the support layer 100, a physical method, such as corona or plasma treatment, or a chemical etching method is used to treat the surface of the support layer 100, so as to form such a structure with low sites and high sites on the upper and lower surfaces of the support layer 100, so that the metal coating 200 of the composite current collector after coating also forms a high-low structure, and then the metal coating 200 on the surface of the composite current collector forms a structure similar to a hole, which helps to release stress and prevent curling, etc. On the other hand, when the active material is coated on the composite current collector, the hole can be more closely combined with the active material to prevent the active material from falling off. More active materials can also be coated to increase the energy density of the battery. Preferably, the number of high sites on the support layer 100 is 2-5 times the number of low sites, so that better effects can be achieved.

[0040] Preferably, in the lightweight composite current collector of the utility model, a lithium-philic layer is also provided on the metal coating 200, and the thickness of the lithium-philic layer is 10nmn-50nm. At this time, since the metal coating 200 on the surface of the composite current collector is affected by the high and low positions of the support layer 100 to form holes, the lithium-philic layer is both in the holes and covers other positions. By providing the lithium-philic coating, on the one hand, the lithium source can be supplemented for the battery, and on the other hand, the metal coating 200 can be protected from oxidation, thereby improving the battery performance.

[0041] Preferably, in the lightweight composite current collector of the utility model, an anti-corrosion layer is also provided between the metal coating 200 and the support layer 100. When the metal coating 200 is prepared by vacuum evaporation, the anti-corrosion layer is also formed in the evaporation cavity, that is, the anti-corrosion layer is first formed on the support layer 100, and then the metal coating 200 is formed on the anti-corrosion layer. The one-step coating improves the coating efficiency and prevents the coating from being oxidized. The particle microstructure of the anti-corrosion layer is circular or elliptical or other polygonal structure. The main function of the anti-corrosion layer is to prevent the electrolyte from corroding the support layer 100, and at the same time, it can also enhance the bonding force between the metal coating 200 and the support layer 100. From the microscopic structure, the morphological characteristics of the anti-corrosion layer are circular or elliptical or other polygonal structures, which are different from the morphology of the metal coating 200. It is preferably a multi-deformation structure, and the particles of the radiation protection layer are in close contact with each other, which can prevent the electrolyte from corroding the support layer 100 and improve the service life. The material of the anti-corrosion layer can be aluminum oxide, silicon oxide, etc.

[0042] The preparation method of the lightweight composite current collector provided by the utility model is as follows Figure 6 As shown, it includes the following steps:

[0043] S100, providing a support layer, and placing the support layer in a vacuum chamber;

[0044] S200, coating the upper and lower surfaces of the support layer with metal coatings respectively by vacuum evaporation to obtain a metal-coated support layer, wherein the thickness of the metal coating is 500nm-1500nm;

[0045] S300, cooling the metal-coated support layer to obtain the lightweight composite current collector.

[0046] The preparation method of the lightweight composite current collector of the utility model is a one-step molding method. First, a support layer is taken, and then the support layer is placed in a vacuum cavity, vacuumized, and then a metal coating with a thickness of 500nm-1500nm is formed on the upper and lower surfaces of the support layer in the vacuum cavity by vacuum evaporation. Vacuum evaporation refers to: melting the metal into a liquid state, forming metal vapor and starting to volatilize, and then condensing the atoms in the vapor on the surface of the polymer material for deposition and growth. The deposition rate of vacuum evaporation is 3-4 times that of magnetron sputtering, which can quickly make up the thickness of the metal coating. Its advantages are 1) heating and melting, fast film formation rate, and high efficiency; 2) evaporation and attachment do not require a high voltage electric field, the equipment is relatively simple and easy to operate; 3) vacuum heating evaporation has low atomic momentum and uniform film thickness. The one-time molding method completes the coating in a vacuum cavity, and there is no need to frequently open and close the vacuum cavity, which is more energy-saving and more efficient. At the same time, because there is no need to open and close the vacuum cavity, there is no process of transporting to the next workspace after production in multiple molding, so the coating can be prevented from being oxidized and the yield rate can be improved.

[0047] The utility model forms a metal coating on the support layer in one step by vacuum evaporation. Such a one-step forming structure can improve the mutual binding force of metal particles and prevent the problem of easy falling off of the metal layer caused by multiple forming. At the same time, by controlling the thickness of the metal coating formed in one step on the upper and lower surfaces, the mass of the lightweight composite current collector can be reduced, which helps to improve the mass energy density of the battery. Among them, the thickness of the metal coating is preferably 1um, because at this thickness of 1um, while maintaining the lightweight of the composite current collector, it can provide better conductivity.

[0048] Preferably, the step of coating the metal coating on the upper and lower surfaces of the support layer respectively by vacuum evaporation method comprises:

[0049] The upper and lower surfaces of the support layer in the vacuum chamber are coated multiple times by vacuum evaporation method, and the moving speed of the support layer in the vacuum chamber and the number of evaporation boats arranged in the vacuum chamber are adjusted according to preset parameters each time the coating is performed, so that at least part of the particles of the metal coating are not perpendicular to the support layer.

[0050] At least some particles of the metal coating formed on the upper and lower surfaces of the support layer are not perpendicular to the support layer. The columnar inclined particles having a certain inclination angle with the support layer are obtained by controlling the speed of the support layer in the vacuum chamber and the number of evaporation boats arranged in the vacuum chamber during coating. For example, in production, the speed of the support layer in the vacuum chamber is controlled to be 5-7 m / min. Two evaporation areas are arranged in the vacuum chamber. The number of evaporation boats in each evaporation area is 10-16 in total, which are divided into two rows, with 5-8 evaporation boats in one row, and are arranged alternately on the left and right. During the vacuum evaporation process, the metal melts into liquid in the evaporation boat, forming metal vapor and starting to volatilize. The atoms in the vapor are rapidly transmitted to the upper support layer in a linear motion without collision. The gaseous particles that reach the surface of the support layer are attached to the surface of the support layer for deposition and growth. The deposition position and angle of the metal particles on the support layer are related to the starting position of the metal particles (i.e., the arrangement position and number of the evaporation boats in the vacuum chamber), and also to the moving speed of the support layer itself (i.e., the speed of the support layer in the vacuum chamber). By controlling the speed of the support layer in the vacuum chamber and the number and distribution of the evaporation boats during production, columnar particles with an inclination angle of 45°-90° with the support layer can be obtained, thereby improving the life of the composite current collector. This method is specifically implemented in a vacuum evaporation device for suspension plating. Suspension plating refers to the support layer passing through the upper part of the evaporation boat and then cooling the support layer, rather than cooling it when passing through the upper part of the evaporation boat. Suspension plating can make the coating more uniform, the cooling effect is better, and the coating quality is higher.

[0051] Moreover, by adjusting the parameters during multiple coatings, the evaporation is performed at different travel speeds and the number of evaporation boats arranged each time the coating is performed, thereby adjusting the content of inclined particles in the metal coating, so that a part of the columnar particles in the metal coating is not perpendicular to the support layer, and another part of the columnar particles is perpendicular to the support layer. For example, in a vacuum chamber for suspension plating, a fast travel speed and a small number of evaporation boats can be used to form a small number or a large number of inclined columnar particles on the support layer, and then a slow travel speed and more or fewer evaporation boats can be used to form vertical particles. The presence of vertical particles can release the stress formed by the metal coating of the inclined particles. The stresses offset each other, which can greatly reduce the curling and warping of the plated film, affecting the adhesion of the current collector and the processing performance of subsequent processes such as coating of the current collector.

[0052] Preferably, before the step of coating the upper and lower surfaces of the support layer with metal coatings by vacuum evaporation to obtain the metal-coated support layer, the method further comprises:

[0053] The support layer is surface treated to obtain a structure with low sites and high sites on the upper and lower surfaces of the support layer.

[0054] The utility model performs surface treatment on the support layer before forming the metal coating, so that the surface of the support layer of the subsequent coating is not smooth. Physical methods, such as corona or plasma treatment, or chemical etching methods can be used to treat the support layer, so as to form a structure with low sites and high sites on the upper and lower surfaces of the support layer, wherein the low site is a region below the plane where the support layer is located, and the high site is a region above the plane where the support layer is located. Multiple high sites surround the low site, and the particles of the metal coating after the metal coating is evaporated are located in the low site and the high site. The upper and lower surfaces of the support layer are formed by surface treatment to form such a structure with low sites and high sites, so that the metal coating of the composite current collector after coating also forms a high-low structure, and then the metal coating on the surface of the composite current collector forms a structure similar to a hole, which helps to release stress and prevent curling, etc. on the one hand, and on the other hand, when the active material is coated on the composite current collector, the hole can be more closely combined with the active material to prevent the active material from falling off. More active materials can also be coated to improve the energy density of the battery. Preferably, the number of high sites on the support layer is 2-5 times the number of low sites, so that better effects can be achieved.

[0055] Preferably, an optical density tester can be added to the vacuum evaporation. The optical density tester directly senses the light transmittance or optical density of the film through optical contact, and uses a certain proportional relationship between optical density and coating thickness to detect the uniformity of coating thickness. By adding an optical density tester to the vacuum evaporation, the thickness of the coating formed on the support layer can be detected online at any time. In this way, there is no need to open the cavity and then use a square resistance tester to detect the coating thickness, so that the coating thickness is accurately controllable, which effectively improves the preparation efficiency and performance reliability of the lightweight composite current collector.

[0056] In summary, the utility model provides a lightweight composite current collector, including a support layer, the upper and lower surfaces of the support layer are provided with a metal coating, the metal coating is formed on the support layer in one molding, and the thickness of the metal coating is 500nm-1500nm. The lightweight composite current collector of the utility model forms a metal coating on the upper and lower surfaces of the support layer by one molding. Such a structure can improve the mutual binding force of metal particles and prevent the problem of easy detachment of the metal layer caused by multiple moldings. The metal coating adopts a suitable thickness, which can provide better conductivity while maintaining the lightweight of the composite current collector, which is beneficial to improving battery performance.

[0057] The above contents are further detailed descriptions of the present invention in combination with specific preferred implementations, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For technicians in the technical field to which the present invention belongs, several equivalent substitutions or obvious variations can be made without departing from the concept of the present invention, and the performance or use is the same, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A lightweight composite current collector, characterized in that: It comprises a supporting layer, wherein the upper and lower surfaces of the supporting layer are both provided with a metal coating, the metal coating is formed on the supporting layer in one step, and the thickness of the metal coating is 500nm-1500nm.

2. The lightweight composite current collector according to claim 1, characterized in that: The thickness of the metal coating is 1 um.

3. The lightweight composite current collector according to claim 1, characterized in that: The material of the metal coating is one or more of aluminum metal, nickel metal, titanium metal, copper metal, nickel alloy, copper alloy, aluminum alloy, and titanium alloy.

4. The lightweight composite current collector according to claim 1, characterized in that: The particles of the metal coating are columnar particles formed at one time, and at least part of the columnar particles are inclined particles that are not perpendicular to the support layer.

5. The lightweight composite current collector according to claim 4, characterized in that: The angle between the inclined particles in the metal coating and the support layer is greater than 45° and less than 90°.

6. The lightweight composite current collector according to claim 4, characterized in that: The content of the inclined particles in the metal coating is 80%-90%.

7. The lightweight composite current collector according to claim 4, characterized in that: The diameter of the inclined particles is greater than 50 nm and less than or equal to 150 nm.

8. The lightweight composite current collector according to claim 4, characterized in that: The average gap between particles of the metal coating is greater than 0 nm and less than or equal to 10 nm.

9. The lightweight composite current collector according to claim 4, characterized in that: The upper and lower surfaces of the support layer have a structure of low points and high points, wherein the low points are areas below the plane where the support layer is located, and the high points are areas above the plane where the support layer is located, the particles of the metal coating are located within the low points and the high points, and multiple high points surround the low points.

10. The lightweight composite current collector according to claim 4, characterized in that: An anti-corrosion layer is also arranged between the metal coating and the support layer, and the particle microstructure of the anti-corrosion layer is circular, elliptical or other polygonal structures.

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