Non-sticky composite current collector

Abstract

The utility model provides a non-sticky composite current collector, which comprises a supporting layer, the supporting layer is provided with a first coating and a second coating in the thickness direction, the first coating is arranged on one surface of the supporting layer, the second coating is arranged on the other surface of the supporting layer, and the first coating is arranged on the other surface of the supporting layer. The particle microstructure of the first coating is different from the particle microstructure of the second coating. According to the non-sticky composite current collector disclosed by the utility model, the first coating and the second coating which are different in particle microstructure are respectively formed on the two surfaces of the supporting layer, so that when the first coating and the second coating are in contact with each other, particles cannot be bonded together due to mutual penetration; and the condition that the contact parts of the composite current collector cannot be opened or the surface is damaged due to mutual adhesion in the rolling, storing and transporting processes is avoided, the qualified rate of finished products of the composite current collector is effectively improved, and the battery performance is favorably improved.

Description

Technical Field

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

[0002] The composite current collector is a new type of current collector material composed of a polymer material and a metal. 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, with metal layers on the two surfaces. Compared with traditional pure metal current collectors, the composite current collector has advantages in safety and potential cost-effectiveness.

[0003] However, the composite current collectors currently produced by manufacturers are usually rolled up for storage and transportation. During the rolling, storage and transportation process, the parts of the composite current collectors that contact each other are prone to adhesion, resulting in the composite current collector being unable to be opened or being forced to open, causing damage to its surface, thereby 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 non-stick composite current collector, aiming to solve the problem that the composite current collector is prone to sticking when winding, and to improve the qualified rate of the finished 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 non-stick composite current collector, which includes a support layer, wherein the support layer has a first coating and a second coating in the thickness direction, the first coating is arranged on one surface of the support layer, and the second coating is arranged on the other surface of the support layer, and the particle microstructure of the first coating is different from the particle microstructure of the second coating.

[0007] In one embodiment, the materials of the first coating layer and the second coating layer are independently selected from one or more of aluminum metal, nickel metal, titanium metal, copper metal, nickel alloy, copper alloy, aluminum alloy, and titanium alloy.

[0008] In one embodiment, the particles of the first coating layer are vertical columnar particles, and at least some of the particles of the second coating layer are inclined columnar particles.

[0009] In one embodiment, the particles of the first coating layer are flat particles, and the particles of the second coating layer are columnar particles.

[0010] In one embodiment, the angle between the inclined columnar particles and the support layer is greater than 45° and less than 90°.

[0011] In one embodiment, the content of the oblique columnar particles in the second coating layer is 80%-90%.

[0012] In one embodiment, the first coating layer or the second coating layer is further provided with an oxide layer of the first coating layer or an oxide layer of the second coating layer respectively.

[0013] In one embodiment, the roughness of the first coating layer is different from the roughness of the second coating layer.

[0014] In one embodiment, the difference between the roughness of the first coating layer and the roughness of the second coating layer is 0.02ra-0.1ra.

[0015] In one embodiment, the support layer has a density greater than the first and second coating layers.

[0016] Compared to the prior art, the present invention provides a non-stick composite current collector comprising a support layer having a first coating layer and a second coating layer in the thickness direction, the first coating layer being disposed on one surface of the support layer, and the second coating layer being disposed on another surface of the support layer, wherein the particle microstructure of the first coating layer is different from the particle microstructure of the second coating layer. The present invention provides a non-stick composite current collector by forming a first coating layer and a second coating layer with different particle microstructures on the two surfaces of the support layer, respectively. This prevents the particles of the first coating layer and the second coating layer from penetrating each other and bonding together when they come into contact with each other. This prevents the contacting portions of the composite current collector from becoming stuck or becoming damaged due to adhesion during winding, storage, and transportation, effectively improving the finished product qualification rate of the composite current collector and contributing to improved battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative work. In the drawings:

[0018] Figure 1 This is a schematic structural diagram of a non-stick composite current collector in an embodiment of the present utility model;

[0019] Figure 2 This is an electron microscope image of the second coating layer of the non-stick composite current collector in an embodiment of the present utility model;

[0020] Figure 3 This is another electron microscope image of the second coating layer of the non-stick composite current collector in an embodiment of the present utility model;

[0021] Figure 4 This is a flow chart of a method for preparing a non-stick composite current collector in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] 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.

[0023] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. 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, the term "connected" can be used for both fixing and circuit connection.

[0024] 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 present invention 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 present invention.

[0025] 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 the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of such 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 they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this utility model.

[0026] The utility model provides a non-stick composite current collector, such as Figure 1 As shown, the non-stick composite current collector includes a support layer 100, wherein the support layer 100 has a first coating layer 201 and a second coating layer 202 in the thickness direction. The first coating layer 201 is disposed on one surface of the support layer 100, and the second coating layer 202 is disposed on the other surface of the support layer 100, for example Figure 1The first coating layer 201 is disposed on the upper surface of the support layer 100, and the second coating layer 202 is disposed on the lower surface of the support layer 100. Of course, the first coating layer 201 can also be disposed on the lower surface of the support layer 100, and the second coating layer 202 can be disposed on the upper surface of the support layer 100. This is not limited in this embodiment. The particle microstructure of the first coating layer 201 is different from the particle microstructure of the second coating layer 202. Since the first coating layer 201 and the second coating layer 202 disposed on the two surfaces of the composite current collector will contact each other during the winding, storage and transportation process, the present invention forms the first coating layer 201 and the second coating layer 202 with different particle microstructures on the two surfaces of the support layer 100, respectively, so that when the first coating layer 201 and the second coating layer 202 contact each other, the particles will not penetrate each other and stick together, so that the parts of the composite current collector that contact each other during the winding, storage and transportation process will not be unable to be opened or the surface will be damaged due to mutual adhesion, effectively improving the qualified rate of the finished composite current collector and helping to improve battery performance.

[0027] Specifically, the support layer 100 is a film made from at least one of 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 thin film made of a polymer material as the support layer 100 improves the safety and lightweight properties of the current collector, thereby increasing the battery's energy density.

[0028] In the present invention, PP film is preferably used as the support layer 100 because it is more acid- and alkali-resistant and can greatly increase the service life of the composite current collector of the present invention. The PP film is preferably 3um-8um thick, which can reduce the weight of the current collector of the present invention and increase the energy density of the battery.

[0029] Preferably, the thickness of the first coating layer 201 and the second coating layer 202 is 1 μm. This thickness provides good conductivity while maintaining the composite current collector's lightness. However, thicker coatings reduce its density, which in turn affects the conductivity. By using first and second coating layers 201 and 202 of appropriate thickness and having different particle microstructures, the lightweight properties of the composite current collector are improved while preventing adhesion.

[0030] Specifically, the materials of the first coating layer 201 and the second coating layer 202 are independently selected from one or more of aluminum, nickel, titanium, copper, nickel alloy, copper alloy, aluminum alloy, and titanium alloy. The materials of the first coating layer 201 and the second coating layer 202 can be the same, for example, both the first coating layer 201 and the second coating layer 202 are made of copper; or the materials of the first coating layer 201 and the second coating layer 202 can be different, for example, the first coating layer 201 is made of copper and the second coating layer 202 is made of a nickel alloy. The material selection can be flexible based on actual needs.

[0031] Preferably, in the non-stick composite current collector of the present invention, the particles of the first coating 201 are vertical columnar particles, and at least part of the particles of the second coating 202 are inclined columnar particles. That is, the first coating 201 and the second coating 202 in this embodiment are similar in that the microscopic particles of both are columnar particles, preferably grown on both surfaces of the support layer 100 in a one-time molding process to improve the bonding force of the metal particles; the difference is that the particles of the first coating 201 are vertical columnar particles that remain perpendicular to the support layer 100, while the particles of the second coating 202 include at least part of inclined columnar particles that are not perpendicular to the support layer 100, such as Figure 2 As shown, it is a microstructure diagram of the second coating 202. The particles of the second coating 202 are columnar particles, which are formed in one step and grown on the support layer 100. The columnar particles are not formed vertically on the support layer 100. At least part of the columnar particles are inclined columnar particles that form a certain angle with the support layer 100. In this way, not only the particle microstructures of the first coating 201 and the second coating 202 are different, achieving a non-stick effect, but also compared to particles arranged vertically 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, thereby improving the life of the composite current collector of the present invention. Specifically, the particles of the second coating 202 can all be inclined columnar particles, or some can be inclined columnar particles and the remaining part can be vertical columnar particles. The content of the inclined columnar particles can be flexibly adjusted according to demand, and this embodiment does not limit this.

[0032] Preferably, in the non-stick composite current collector of the present invention, the particles of the first coating layer 201 are flat particles, and the particles of the second coating layer 202 are columnar particles. That is, in this embodiment, by making the microstructure of the particles of the first coating layer 201 a flat structure, such as a circular, elliptical, or other polygonal structure, and the microstructure of the particles of the second coating layer 202 a columnar structure, such as all vertical columnar particles, all inclined columnar particles, or a combination of vertical columnar particles and inclined columnar particles, the purpose of achieving different microparticle structures of the coatings on the two surfaces of the support layer 100 can be achieved, thereby preventing the coatings from sticking to each other.

[0033] Furthermore, in the non-stick composite current collector of the present invention, when there are inclined columnar particles in the second coating layer 202, the angle between the inclined columnar particles and the support layer 100 is greater than 45° and less than 90°. When forming the second coating layer 202 having inclined columnar particles on the support layer 100, taking the vacuum evaporation method as an example, the inclination angle of the inclined columnar 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 5-7 m / min. In the vacuum chamber, there are two evaporation areas, and the number of evaporation boats in each evaporation area is 10-16 in total, divided into two rows, 5-8 in each row, and arranged alternately on the left and right. During the vacuum evaporation process, the metal melts into liquid in the evaporation boat, forming metal vapor that begins to evaporate. The atoms in the vapor are rapidly transported to the upper support layer 100 in a linear motion with basically no collision. The gaseous particles reaching the surface of the support layer 100 adhere to the surface of the support layer 100, deposit and grow. The deposition position and angle of the metal particles on the support layer 100 are related to the starting position of the metal particles (that is, 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 (that is, 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° to 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 over the top of the evaporation boat and then is cooled, rather than being cooled while passing over the evaporation boat. Suspended plating can make the coating more uniform, the cooling effect better, and the coating quality higher.

[0034] Furthermore, in the non-stick composite current collector of the present invention, when there are inclined columnar particles in the second coating 202, the content of the inclined columnar particles in the second coating 202 is 80%-90%, and the remaining columnar particles can be vertical particles perpendicular to the support layer 100. The second coating 202 has both inclined columnar particles and vertical particles. The presence of vertical particles can release the stress formed by the second coating 202 of the inclined columnar 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 columnar 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 large number 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, multiple evaporation boats or a small number of evaporation boats are used to form vertical particles. For example, when forming 80%-90% columnar inclined columnar particles, a film speed of 2-3 m / min can be first used, and the number of evaporation boats can be 2-3 in a row, 2 rows in total, and cross-arranged, totaling 4-6; then suspended vacuum evaporation can be used, and a travel speed of 5-7 m / min can be used, combined with a row of 4-6, 2 rows in total, and evaporation boats arranged opposite to each other for coating, thereby forming a second coating 202 with both inclined columnar particles and vertical particles on the support layer 100, thereby improving the performance of the composite current collector.

[0035] Furthermore, in the non-stick composite current collector of the present invention, the diameter of the angled columnar particles is greater than 50 nm and less than or equal to 150 nm. Composite current collectors with such metal-coated particles can be formed more quickly, reducing overall cost and are less likely to fall off.

[0036] Furthermore, in the non-stick composite current collector of the present invention, the average gap between the metal coating particles is greater than 0 nm and less than or equal to 10 nm, which can make the coating of the composite current collector more compact. Figure 2 As shown, when used in a battery, it is difficult for the electrolyte to penetrate and react with the support layer, thereby improving the service life of the battery.

[0037] Preferably, in the non-stick composite current collector of the present invention, an oxide layer of the first coating layer 201 or an oxide layer of the second coating layer 202 is also provided on the first coating layer 201 or the second coating layer 202, respectively. Based on the different particle microstructures of the first coating layer 201 and the second coating layer 202, the oxide layer of the first coating layer 201 or the second coating layer 202 is formed on the first coating layer 201 or the second coating layer 202. This makes the first coating layer 201 or the second coating layer 202 structurally different from the oxide layer, thereby preventing the first coating layer 201 and the second coating layer 202 from adhering to each other and improving the anti-sticking effect.

[0038] Preferably, the thickness of the oxide layer is 10 nm to 50 nm, which can reduce damage to the conductive properties of the first coating layer 201 or the second coating layer 202 and also prevent the first coating layer 201 and the second coating layer 202 from adhering to each other.

[0039] Preferably, in the non-stick composite current collector of the present invention, the roughness of the first coating layer 201 is different from the roughness of the second coating layer 202. By performing roughness treatment on the first coating layer 201 or the second coating layer 202, for example, by changing the roughness of the first coating layer 201 or the second coating layer 202 through roughness treatment methods such as plasma treatment, corona treatment, or manual polishing, the roughness of the first coating layer 201 or the second coating layer 202 is different, thereby preventing the first coating layer 201 and the second coating layer 202 from adhering to each other, thereby improving the anti-adhesion effect. After unlimited tests by the inventors, the best effect is achieved when the difference between the roughness of the first coating layer 201 and the roughness of the second coating layer 202 is in the range of 0.02ra-0.1ra. If it is too high, the surface stress of the first coating layer 201 and the second coating layer 202 will be damaged, resulting in curling.

[0040] Preferably, in the non-stick composite current collector of the present invention, the density of the support layer 100 is greater than the density of the first coating layer 201 and the second coating layer 202. This prevents the first coating layer 201 and the second coating layer 202 from burning holes in the support layer 100 when the first coating layer 201 and the second coating layer 202 are formed on the support layer 100, thereby improving the qualified rate of the finished product.

[0041] Preferably, in the non-stick composite current collector of the present invention, the upper and lower surfaces of the support layer 100 have a structure of low sites and high sites, wherein the low sites are areas below the plane where the support layer 100 is located, and the high sites are areas above the plane where the support layer 100 is located. The particles of the first coating 201 and the second coating 202 are located within the low sites and the high sites, and multiple high sites surround the low sites. Figure 3As shown at the bottom of the figure, the surface of the support layer 100 in the composite current collector of the present invention is not smooth. Before preparing the first coating layer 201 and the second coating layer 202 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 first used to treat the surface of the support layer 100. This structure with low sites and high sites is formed on the upper and lower surfaces of the support layer 100. As a result, the first coating layer 201 and the second coating layer 202 of the composite current collector also form a high-low structure after coating, thereby forming a coating layer on the surface of the composite current collector that is similar to a hole structure. On the one hand, it helps to release stress and prevent curling. On the other hand, when the active material is coated on the composite current collector, the holes can be more tightly combined with the active material to prevent the active material from falling off. More active material 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, which can achieve better results.

[0042] Preferably, in the non-stick composite current collector of the present invention, a lithium-philic layer is further provided on the first coating layer 201 and the second coating layer 202, and the thickness of the lithium-philic layer is 10nmn-50nm. At this time, since the first coating layer 201 and the second coating layer 202 on the surface of the composite current collector are affected by the high and low points of the support layer 100 to form holes, the lithium-philic layer covers both inside the holes and other positions. By providing the lithium-philic coating, on the one hand, the lithium source can be replenished for the battery, and on the other hand, the metal coating can be protected from oxidation, thereby improving the battery performance.

[0043] Preferably, in the non-stick composite current collector of the present invention, an anti-corrosion layer is further provided between the first coating layer 201 and the second coating layer 202 and the support layer 100. When the first coating layer 201 and the second coating layer 202 are prepared by vacuum evaporation, the anti-corrosion layer is also formed in the evaporation chamber, that is, the anti-corrosion layer is first formed on the two surfaces of the support layer 100, and then the first coating layer 201 and the second coating layer 202 are respectively formed on the anti-corrosion layers on the two surfaces. The one-step coating method improves the coating efficiency and prevents the coating from being oxidized. The particle microstructure of the anti-corrosion layer is circular, 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 first coating layer 201 and the second coating layer 202 and the support layer 100. From the microstructural point of view, the morphological characteristics of the anti-corrosion layer are circular, elliptical or other polygonal structures, which are different from the morphology of the first coating layer 201 and the second coating layer 202. Preferably, the multi-deformation structure is used, 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.

[0044] The present invention also provides a method for preparing a non-stick composite current collector. Figure 4 As shown, it includes the following steps:

[0045] S100, providing a support layer, and placing the support layer in a vacuum chamber;

[0046] S200, forming a first coating layer on one surface of the support layer and forming a second coating layer on the other surface of the support layer by vacuum evaporation to obtain a metal-coated support layer, wherein the particle microstructure of the first coating layer is different from the particle microstructure of the second coating layer;

[0047] S300, cooling the metal-coated support layer to obtain the non-stick composite current collector.

[0048] The preparation method of the non-stick composite current collector of the present invention is a one-step molding method. First, a support layer is taken, and then the support layer is placed in a vacuum cavity, vacuumed, and then a metal coating with a thickness of 1um is formed on the upper and lower surfaces of the support layer in the vacuum cavity multiple times by vacuum evaporation. The metal coating includes a first coating and a second coating with different particle microstructures. Vacuum evaporation refers to: melting the metal into a liquid to form metal vapor and start to evaporate, and then condensing the atoms in the vapor to deposit and grow on the surface of the polymer material. The deposition speed of vacuum evaporation is 3-4 times that of magnetron sputtering, and the thickness of the metal coating can be quickly supplemented. Its advantages are: 1) heating and melting, fast film forming rate, and high efficiency; 2) evaporation and adhesion do not require a high voltage electric field, the equipment is relatively simple and easy to operate; 3) the momentum of vacuum heating evaporation atoms is low, and the film thickness is uniform. The one-shot molding method completes the coating in a vacuum chamber without the need to frequently open and close the vacuum chamber, which saves energy and is more efficient. At the same time, because there is no need to open and close the vacuum chamber, there is no process of transferring to the next workspace after production in multiple molding, so the coating can be avoided from being oxidized and the yield rate can be improved.

[0049] The utility model forms a first coating layer and a second coating layer with different particle microstructures on the two surfaces of the support layer in one step by vacuum evaporation, so that when the first coating layer and the second coating layer contact each other, the particles will not penetrate each other and stick together, so that the parts of the composite current collector that contact each other during the winding, storage and transportation process will not be unable to be opened or the surface will be damaged due to mutual adhesion, which effectively improves the qualified rate of the finished product of the composite current collector and is beneficial to improving battery performance.

[0050] Preferably, before the step of forming a first coating on one surface of the support layer and forming a second coating on the other surface of the support layer by vacuum evaporation to obtain the metal-coated support layer, the method further comprises:

[0051] The support layer is surface treated to obtain structures with low sites and high sites on the upper and lower surfaces of the support layer.

[0052] The present invention performs a surface treatment on the support layer before forming the metal coating, so that the surface of the support layer after 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 surface, thereby forming a structure with low points and high points on the upper and lower surfaces of the support layer, wherein the low points are areas below the plane of the support layer, and the high points are areas above the plane of the support layer. Multiple high points surround the low points, and after the metal coating is evaporated, the particles of the metal coating are located within the low and high points. This structure with low points and high points is formed by surface treatment on the upper and lower surfaces of the support layer, so that the metal coating of the composite current collector after coating also forms a high-low structure, which in turn forms a structure similar to holes on the surface of the composite current collector. This not only helps to relieve stress and prevent curling, but also allows the holes to more tightly bind to the active material when the active material is coated on the composite current collector, preventing the active material from falling off. It also allows for the coating of more active material, thereby increasing the energy density of the battery. Preferably, the number of high points on the support layer is 2-5 times the number of low points, which can achieve better results.

[0053] Preferably, after the step of forming a first coating on one surface of the support layer and a second coating on the other surface of the support layer by vacuum evaporation to obtain the metal-coated support layer, the method further comprises:

[0054] The first coating layer or the second coating layer is subjected to roughness treatment so that the roughness of the first coating layer is different from the roughness of the second coating layer.

[0055] After forming the first and second coatings on both surfaces of the support layer, the present invention further modifies the roughness of the first or second coatings through a roughness treatment method such as plasma treatment, corona treatment, or manual polishing, thereby varying the roughness of the first and second coatings. This prevents the first and second coatings from adhering to each other, thereby improving the anti-adhesion effect. The inventors of the present invention have conducted numerous tests and found that the optimal effect is achieved when the difference in roughness between the first and second coatings is between 0.02ra and 0.1ra. A higher difference in roughness can damage the surface stress of the first and second coatings, leading to curling.

[0056] Preferably, an optical density tester can be incorporated into the vacuum evaporation process. This instrument directly senses the transmittance or optical density of the film through optical contact, and uses the proportional relationship between optical density and coating thickness to detect the uniformity of the coating thickness. By incorporating an optical density tester into the vacuum evaporation process, the thickness of the coating formed on the support layer can be measured online at any time. This eliminates the need to open the chamber and use a square resistance tester to measure the coating thickness, making the coating thickness precisely controllable and effectively improving the preparation efficiency and performance reliability of the non-stick composite current collector.

[0057] In summary, the present invention provides a non-sticky composite current collector, which includes a support layer, wherein the support layer has a first coating layer and a second coating layer in the thickness direction, wherein the first coating layer is disposed on one surface of the support layer, and the second coating layer is disposed on another surface of the support layer, and the particle microstructure of the first coating layer is different from the particle microstructure of the second coating layer. The non-sticky composite current collector of the present invention forms a first coating layer and a second coating layer with different particle microstructures on the two surfaces of the support layer, respectively, so that when the first coating layer and the second coating layer contact each other, the particles do not penetrate each other and stick together, so that the parts of the composite current collector that contact each other during the winding, storage and transportation process will not be unable to be opened or the surface will be damaged due to mutual adhesion, effectively improving the qualified rate of the finished composite current collector and helping to improve battery performance.

[0058] The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention cannot be considered to be limited to these descriptions. For those skilled in the art of the present invention, it is possible to make several equivalent substitutions or obvious modifications without departing from the concept of the present invention, and the performance or use are the same, and all of them should be considered to fall within the scope of protection of the present invention.

Claims

1. A non-stick composite current collector, characterized in that: The invention comprises a supporting layer, wherein the supporting layer has a first coating layer and a second coating layer in a thickness direction, wherein the first coating layer is arranged on one surface of the supporting layer, and the second coating layer is arranged on the other surface of the supporting layer. wherein the particles of the first coating are vertical columnar particles, and at least part of the particles of the second coating are inclined columnar particles; or The particles of the first coating layer are flat particles, and the particles of the second coating layer are columnar particles.

2. The non-stick composite current collector according to claim 1, characterized in that: The materials of the first coating layer and the second coating layer are independently selected from one of aluminum metal, nickel metal, titanium metal, copper metal, nickel alloy, copper alloy, aluminum alloy, and titanium alloy.

3. The non-stick composite current collector according to claim 1, characterized in that: The angle between the inclined columnar particles and the support layer is greater than 45° and less than 90°.

4. The non-stick composite current collector according to claim 1, characterized in that: The content of the inclined columnar particles in the second coating layer is 80%-90%.

5. The non-stick composite current collector according to claim 1, characterized in that: The first coating layer or the second coating layer is also provided with an oxide layer of the first coating layer or an oxide layer of the second coating layer correspondingly.

6. The non-stick composite current collector according to claim 1, characterized in that: The roughness of the first coating layer is different from the roughness of the second coating layer.

7. The non-stick composite current collector according to claim 6, characterized in that: The difference between the roughness of the first coating layer and the roughness of the second coating layer is 0.02ra-0.1ra.

8. The non-stick composite current collector according to claim 1, characterized in that: The support layer has a density greater than that of the first coating layer and the second coating layer.

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