Composite current collector and preparation method thereof

Abstract

The invention relates to a composite current collector and a preparation method thereof. The composite current collector comprises a base film, and a first conductive layer and a second conductive layer which are respectively arranged on two sides of the base film. The composite current collector comprises a base film, a flat section and at least one crease-resistant structure are arranged in the transverse extension direction of the base film, and the ratio of the width of the crease-resistant structure to the width of the flat section is 1: 3-1: 15. According to the composite current collector provided by the embodiment of the invention, in the carrying and packaging process of the composite current collector finished roll formed after rolling, when the end face of the composite current collector finished roll is subjected to longitudinal thrust and transverse thrust, the anti-wrinkling structure wrinkles preferentially to form a barrier, so that wrinkles are effectively prevented from being diffused to other parts of the composite current collector. And the wrinkled sections are cut off before the battery is processed subsequently, so that the yield is improved.

Description

Technical Field

[0001] This application relates to the technical field of lithium battery composite current collectors, and particularly to a composite current collector and a preparation method thereof. Background Art

[0002] The composite current collector is a new material for lithium battery current collectors, and has better performance than traditional metal foils. The composite aluminum current collector adopts a "sandwich" structure of "metal aluminum layer - PET polymer layer - metal aluminum layer", and has application advantages of high safety, long life, high energy density, and low cost. It is expected to replace traditional current collectors and become the main material for future lithium battery current collectors.

[0003] Since the base film of the composite aluminum current collector uses PET polymer material, compared with the current collector of traditional metal foil, the composite aluminum current collector is more likely to wrinkle during processes such as winding, conveying, packaging, and transportation, resulting in inapplicability in the battery manufacturing process. Summary of the Invention

[0004] Based on this, in view of the problem that the composite aluminum current collector is more likely to wrinkle during processes such as winding, conveying, packaging, and transportation, resulting in inapplicability in the battery manufacturing process, it is necessary to provide a composite current collector and a preparation method thereof.

[0005] An embodiment of the first aspect of this application provides a composite current collector, which includes a base film, and a first conductive layer and a second conductive layer respectively disposed on both sides of the base film. The composite current collector includes a flat section disposed along a first direction and at least one anti-wrinkle structure, and the anti-wrinkle structure includes at least one shaped wrinkle.

[0006] In one embodiment, the shaped wrinkle extends along a second direction; the second direction intersects the first direction.

[0007] In one embodiment, anti-wrinkle structures are provided at both ends of the composite current collector along the first direction; the value range of the included angle between the second direction and the first direction facing the opposite anti-wrinkle structure includes: 45° - 90°;

[0008] And / or, the anti-wrinkle structure includes a plurality of shaped wrinkles; the shaped wrinkles in the same anti-wrinkle structure are parallel to each other;

[0009] And / or, anti-wrinkle structures are provided at both ends of the composite current collector along the first direction; the two anti-wrinkle structures are symmetrically arranged with the center line extending along a third direction of the composite current collector as the center of symmetry; the third direction is perpendicular to the first direction.

[0010] In one embodiment, the composite current collector includes a transition section located between the anti-wrinkle structure and the flat section and connecting the flat section and the anti-wrinkle structure;

[0011] Further, the material of the transition section includes one or more of copper, nickel, or zinc; and / or, the width of the transition section in the first direction is 20 mm - 70 mm.

[0012] In one embodiment, the ratio of the width of the anti-wrinkle structure in the first direction to the width of the flat section in the first direction is 1:2 - 1:16;

[0013] and / or, the anti-wrinkle structure is disposed at the edge of the composite current collector, and the distance from the side of the anti-wrinkle structure close to the center of the composite current collector in the first direction to the corresponding end face of the composite current collector is 10 mm - 300 mm.

[0014] In one embodiment, the ductility of the anti-wrinkle structure decreases in the direction from the edge of the composite current collector to the center of the composite current collector.

[0015] In one embodiment, both the first conductive layer and the second conductive layer at the anti-wrinkle structure include a composite aluminum layer composed of aluminum and a target metal, or composed of aluminum and a target metal oxide;

[0016] Wherein, in the composite aluminum layer in the region where the anti-wrinkle structure is located, the ductility of the target metal or the target metal oxide is less than that of aluminum, and the content of the target metal or the target metal oxide increases in the direction from the edge of the composite current collector to the center of the composite current collector; or, the ductility of the target metal or the target metal oxide is greater than that of aluminum, and the content of the target metal or the target metal oxide decreases in the direction from the edge of the composite current collector to the center of the composite current collector.

[0017] In one embodiment, when the composite aluminum layer is composed of aluminum and a target metal, the target metal includes one or more of copper, nickel, or zinc; or, the target metal includes silver;

[0018] When the composite aluminum layer is composed of aluminum and a target metal oxide, the target metal oxide includes aluminum oxide.

[0019] An embodiment of the second aspect of the present application provides a method for preparing a composite current collector, including the following steps:

[0020] Prepare a composite current collector such that the composite current collector includes a flat section and an anti-wrinkle structure formed along a first direction; the anti-wrinkle structure includes at least one shaped fold.

[0021] In one embodiment, the composite current collector includes a base film, and a first conductive layer and a second conductive layer respectively disposed on both sides of the base film; wherein, the preparation of the composite current collector includes:

[0022] Providing the base film;

[0023] Placing the base film on the unwind side of the machine table, and enabling the base film to sequentially pass through an unwind roller, a guide roller, a first main drum, and a second main drum along a preset film passing route, so as to form the first conductive layer by evaporation plating on the first side of the base film through an evaporation boat disposed on the first main drum, and form the second conductive layer by evaporation plating on the second side of the base film through an evaporation boat disposed on the second main drum;

[0024] Wherein, the anti-wrinkle structure is formed during the process of evaporation plating to form the first conductive layer and / or the second conductive layer.

[0025] In one embodiment, the number of the evaporation boats disposed at the first main drum and the second main drum is multiple; both the first conductive layer and the second conductive layer include a composite aluminum layer composed of aluminum and a target metal, or composed of aluminum and a target metal oxide; wherein, the preparation of the composite current collector further includes:

[0026] Before forming the first conductive layer and the second conductive layer, for the evaporation boat used to form the anti-wrinkle structure, along the direction from the edge of the composite current collector to the center of the composite current collector, adjust the content of the target metal or the target metal oxide in the evaporation boat to increase.

[0027] In one embodiment, adjusting the content of the target metal or the target metal oxide in the evaporation boat includes:

[0028] When the target metal is one or more of copper, nickel, or zinc, in the evaporation boat corresponding to the area of the anti-wrinkle structure close to the edge of the composite current collector, the mass ratio range of aluminum to the target metal is 1:2 - 1:4; in the evaporation boat corresponding to the area of the anti-wrinkle structure close to the center of the composite current collector, the mass ratio range of aluminum to the target metal is 1:7 - 1:10;

[0029] When the target metal is silver, in the evaporation boat corresponding to the area of the anti-wrinkle structure close to the edge of the composite current collector, the mass ratio range of aluminum to silver is 1:6 - 1:9; in the evaporation boat corresponding to the area of the anti-wrinkle structure close to the center of the composite current collector, the mass ratio range of aluminum to silver is 1:3 - 1:5;

[0030] When the target metal is aluminum oxide, the oxygen content introduced at the evaporation boat corresponding to the area of the anti-wrinkle structure near the edge of the composite current collector is lower than the oxygen content introduced at the evaporation boat corresponding to the area of the anti-wrinkle structure near the center of the composite current collector.

[0031] In one embodiment, the preparation of the composite current collector further includes:

[0032] Before forming the first conductive layer, flatten the base film through a unwind flattening roller group; between the first main drum and the second main drum, flatten the base film through a transition flattening roller group; after forming the second conductive layer, flatten the base film through a windup flattening roller group; wherein, the wrap angles of the transition flattening roller group and the windup flattening roller group are both smaller than the wrap angle of the unwind flattening roller group;

[0033] The transition flattening roller group sequentially includes a first transition flattening roller and a second transition flattening roller along the movement direction of the base film, and the wrap angle of the second transition flattening roller is larger than the wrap angle of the first transition flattening roller.

[0034] In one embodiment, the preparation of the composite current collector further includes:

[0035] During the evaporation deposition to form the first conductive layer and / or the second conductive layer, adjust the evaporation power of the evaporation equipment to a first power to form the anti-wrinkle structure; adjust the evaporation power of the evaporation equipment to a second power to form the flat section;

[0036] Wherein, the first power is greater than or equal to the thermal damage power of the base film;

[0037] The second power is less than the thermal damage power of the base film;

[0038] The thermal damage power is configured to be able to cause thermal damage to the base film to form the shaped wrinkles.

[0039] In one embodiment, the preparation of the composite current collector further includes:

[0040] Before the base film passes through the first main drum and the second main drum, form a heat insulation layer in the areas of the first main drum and the second main drum corresponding to the anti-wrinkle structure;

[0041] The thickness of the heat insulation layer on the first main drum is less than the thickness of the heat insulation layer on the second main drum.

[0042] According to the composite current collector and its preparation method according to the embodiments of the present application, during the handling and packaging process of the finished roll of the composite current collector formed after winding, when the end face of the finished roll of the composite current collector is subjected to longitudinal thrust and transverse thrust, the anti-wrinkle structure preferentially wrinkles to form a barrier, effectively preventing the wrinkles from spreading to other parts of the composite current collector. Subsequently, the anti-wrinkle structure can be cut off before battery processing, improving the yield rate. Description of the Drawings

[0043] Figure 1 It is a cross-sectional view showing the intermediate layer structure of the composite current collector according to an embodiment of the present application.

[0044] Figure 2 It is a top view of the composite current collector according to an embodiment of the present application.

[0045] Figure 3 It is a cross-sectional view showing the intermediate layer structure of the composite current collector according to another embodiment of the present application.

[0046] Figure 4 It is a flowchart of the preparation method of the composite current collector according to an embodiment of the present application.

[0047] Figure 5 It is a flowchart of the preparation method of the composite current collector according to another embodiment of the present application.

[0048] Figure 6 It is a schematic diagram of the evaporation equipment in the preparation method of the composite current collector according to the embodiment of the present application.

[0049] Reference Signs:

[0050] 1000, composite current collector; 100, base film; 200, first conductive layer; 300, second conductive layer; 400, flat section; 500, anti-wrinkle structure; 510, shaped fold; 600, transition section;

[0051] 2000, unwind roller;

[0052] 3000, guide roller;

[0053] 4000, first main drum; 4100, first evaporation boat;

[0054] 5000, second main drum; 5100, second evaporation boat;

[0055] 6000, first unwind flattening roller; 6100, second unwind flattening roller;

[0056] 7000, first transition flattening roller; 7100, second transition flattening roller; 7200, third transition flattening roller;

[0057] 8000, first winding flattening roller; 8100, second winding flattening roller;

[0058] 9000, the coiling roller. Specific embodiments

[0059] To make the above objects, features, and advantages of the present application more apparent and understandable, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to facilitate a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0060] In the description of the present application, it should be understood that if these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or positional relationship indicated by these terms is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present application.

[0061] In addition, if these terms "first", "second" appear, these terms are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first", "second" may explicitly or implicitly include at least one of such features. In the description of the present application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0062] In the present application, unless otherwise clearly specified and limited, if terms such as "mounted", "connected", "connected to", "fixed" appear, these terms should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0063] In this application, unless otherwise clearly specified and defined, when a first feature is described as being "on" or "under" a second feature or the like, it 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. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or simply means that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or simply means that the first feature has a lower horizontal height than the second feature.

[0064] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intermediate element at the same time. If so, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in this application are only for the purpose of illustration and do not represent the only implementation.

[0065] Referring to Figure 1 , at least one embodiment of this application provides a composite current collector 1000, which includes a base film 100 and a first conductive layer 200 and a second conductive layer 300 respectively disposed on both sides of the base film 100. The composite current collector 1000 includes a flat section 400 disposed along a first direction and at least one anti-wrinkle structure 500, and the anti-wrinkle structure 500 includes at least one shaped fold. Among them, the first direction in the embodiments of this application can refer to Figure 1 the X direction in, that is, the transverse direction of the composite current collector 1000.

[0066] For the composite current collector 1000 according to the embodiment of this application, during the handling and packaging process of the finished roll of the composite current collector 1000 formed after winding, when the end face of the finished roll of the composite current collector 1000 is subjected to longitudinal thrust and transverse thrust, the anti-wrinkle structure 500 folds preferentially to form a barrier, effectively preventing the wrinkles from spreading to other parts of the composite current collector 1000. Then, the anti-wrinkle structure 500 can be cut off before battery processing, improving the yield.

[0067] Referring to Figure 2 , in some embodiments, the shaped folds extend along a second direction; the second direction intersects the first direction. Among them, the second direction in the embodiments of this application can refer to Figure 2 the Y direction in, and the Y direction intersects the X direction.

[0068] Referring to Figure 2, in some embodiments, anti-wrinkle structures 500 are provided at both ends of the composite current collector 1000 along the first direction; the value range of the included angle between the second direction and the first direction facing the opposite anti-wrinkle structure 500 includes: 45° - 90°. Since the wrinkle direction is random and diffusion is not easy to control, through the above settings, an ordered deformation path is formed for the directional wrinkles, the deformation and expansion direction of the wrinkles can be effectively controlled, the wrinkle expansion direction is predictable, and it is convenient for process optimization.

[0069] In some embodiments, the anti-wrinkle structure 500 includes a plurality of shaped wrinkles; the shaped wrinkles within the same anti-wrinkle structure 500 are parallel to each other. Specifically, in some embodiments, an anti-wrinkle structure 500 includes 1 - 5 shaped wrinkles. A single wrinkle may fail under extreme conditions, and multiple wrinkles enhance the protection redundancy to adapt to a large-width composite current collector. Through the above settings, the shaped wrinkles extend along the second direction and are parallel to each other, that is, the shaped wrinkles within an anti-wrinkle structure 500 are parallel to each other, avoiding being too close or too far between the ends of some wrinkles.

[0070] In some embodiments, anti-wrinkle structures 500 are provided at both ends of the composite current collector 1000 along the first direction; the two anti-wrinkle structures 500 are symmetrically arranged with the center line of the composite current collector 1000 extending along the third direction as the center of symmetry; the third direction is perpendicular to the first direction. Among them, the third direction in the embodiments of the present application can refer to Figure 2 the Z direction in, the Z direction is perpendicular to the X direction. The anti-wrinkle structures 500 at both ends of the composite current collector 1000 are symmetrically arranged, which can effectively prevent the wrinkles at both ends of the finished roll from spreading towards the middle of the flat section 400 at the same time, and ensure that the flat section 400 of the finished film is a flat section 400 with a symmetric appearance, which is convenient for slitting the finished film.

[0071] In some embodiments, the top of the shaped wrinkle is arc-shaped, the arc radius is 0.2 mm - 0.8 mm, and the radian is 30° - 120°. Sharp wrinkles are prone to cause stress concentration. In the embodiments of the present application, the shaped wrinkles are set with an arc-shaped top to facilitate stress dispersion, reduce film damage, and extend the service life. When the arc radius and radian are within the above ranges, the formed shaped wrinkles 510 can form a barrier to prevent the subsequent wrinkles from spreading towards the flat section 400. It can be understood that the shaped wrinkles can be set to other shapes according to specific usage situations.

[0072] Refer to Figure 3 , in some embodiments, the composite current collector 1000 includes a transition section 600 located between the anti-wrinkle structure 500 and the flat section 400 and connecting the flat section 400 and the anti-wrinkle structure 500. The transition section 600 is used to prevent the wrinkles from spreading towards the flat section 400 during the evaporation process. Stress cracks are likely to occur at the intersection interface between the anti-wrinkle structure 500 and the flat section 400. Through the setting of the transition section 600, the interface stability is improved to prevent crack propagation.

[0073] Further, in some embodiments, the material of the transition section 600 includes one or more of copper, nickel, or zinc, such that the transition section 600 can buffer stress and maintain electrical conductivity continuity.

[0074] In some embodiments, the width of the transition section 600 in the first direction is 20 mm - 70 mm, ensuring the transition buffer effect of the transition section 600. Exemplarily, the width of the transition section 600 includes, but is not limited to, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, or 70 mm, or within the range formed by any two of the above point values as the end point values.

[0075] Specifically, in some embodiments, the width of the transition section 600 in the first direction is 30 mm - 60 mm.

[0076] In some embodiments, the ratio of the width of the wrinkle prevention structure 500 in the first direction to the width of the flat section 400 in the first direction is 1:2 - 1:16. Within the above range, it is possible to prevent the wrinkles from spreading to the flat section 400. Exemplarily, the above ratio includes, but is not limited to, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, or 1:16, or within the range formed by any two of the above point values as the end point values.

[0077] Specifically, in some embodiments, the ratio of the width of the wrinkle prevention structure 500 in the first direction to the width of the flat section 400 in the first direction is 1:3 - 1:15.

[0078] In some embodiments, the wrinkle prevention structure 500 is disposed at the edge of the composite current collector 1000, and the distance from the side of the wrinkle prevention structure 500 closer to the center of the composite current collector 1000 in the first direction to the corresponding end face of the composite current collector 1000 is 10 mm - 300 mm. The edge region is most susceptible to the influence of heat shrinkage. Through the above setting, the wrinkle prevention structure 500 is preset at the edge to absorb the deformation energy and prevent the wrinkles from spreading to the center, protecting the integrity of the core region.

[0079] It can be understood that the anti-wrinkle structure 500 provided at the edge of the composite current collector 1000 has two sides. One side is the side closer to the center of the composite current collector 1000 in the first direction, and the other side is the side farther from the center of the composite current collector 1000 in the first direction. In the anti-wrinkle structure 500 in the embodiment of the present application, the distance between the side of the anti-wrinkle structure 500 closer to the center of the composite current collector 1000 in the first direction and the corresponding end face of the composite current collector 1000 is 10 mm - 300 mm. Exemplarily, the above distance includes but is not limited to 10 mm, 40 mm, 80 mm, 120 mm, 160 mm, 200 mm, 240 mm, 280 mm or 300 mm, or within the range formed by any two of the above point values as the end point values. Through the above setting, the distance between the innermost side of the anti-wrinkle structure 500 and the end face of the composite current collector 1000 is limited, avoiding that the anti-wrinkle structure 500 is too far from the end face of the composite current collector 1000 and unable to achieve the effect of guiding the wrinkles to the edge of the composite current collector 1000, and at the same time reducing the waste generated when cutting off the wrinkled part subsequently.

[0080] Specifically, in some embodiments, the distance between the side of the anti-wrinkle structure 500 farther from the center of the composite current collector 1000 in the first direction and the corresponding end face of the composite current collector 1000 can be 0, that is, the edge of the anti-wrinkle structure 500 can be aligned with the end face of the composite current collector 1000.

[0081] In some embodiments, the distance between the side of the anti-wrinkle structure 500 closer to the center of the composite current collector 1000 in the first direction and the corresponding end face of the composite current collector 1000 is 10 mm - 200 mm.

[0082] In some embodiments, the ductility of the anti-wrinkle structure 500 decreases along the direction from the edge of the composite current collector 1000 to the center of the composite current collector 1000. That is, the ductility of the anti-wrinkle structure 500 near the edge of the composite current collector 1000 is higher. During the handling and packaging of the finished roll of the composite current collector 1000, when the end face at the edge of the composite current collector 1000 is subjected to longitudinal and transverse thrusts, the wrinkles of the anti-wrinkle structure 500 are more likely to form on the outside, reducing the possibility of the wrinkles spreading towards the middle.

[0083] In some embodiments, both the first conductive layer 200 and the second conductive layer 300 at the wrinkle prevention structure 500 include a composite aluminum layer composed of aluminum and a target metal, or composed of aluminum and a target metal oxide. Among them, in the composite aluminum layer in the area where the wrinkle prevention structure 500 is located, the ductility of the target metal or the target metal oxide is less than that of aluminum, and the content of the target metal or the target metal oxide increases in the direction from the edge of the composite current collector 1000 to the center of the composite current collector 1000; or, the ductility of the target metal or the target metal oxide is greater than that of aluminum, and the content of the target metal or the target metal oxide decreases in the direction from the edge of the composite current collector 1000 to the center of the composite current collector 1000.

[0084] Specifically, in some embodiments, both the first conductive layer 200 and the second conductive layer 300 at the wrinkle prevention structure 500 include a composite aluminum layer composed of aluminum and a target metal. Or, both the first conductive layer 200 and the second conductive layer 300 at the wrinkle prevention structure 500 include a composite aluminum layer composed of aluminum and a target metal oxide.

[0085] Specifically, in some embodiments, in the area of the wrinkle prevention structure 500 of the composite current collector 1000, there are two targeted gradient distribution strategies for the ductility design of the target metal or the target metal oxide in the composite aluminum layer: when the selected target metal or the target metal oxide has a lower ductility than pure aluminum, through vapor deposition processes such as evaporation, in the direction from the edge to the center of the composite current collector 1000, gradually increase the content of the target metal or the target metal oxide, use the higher ductility in the edge area of the composite current collector 1000 to form deformation, use the lower ductility in the center area to inhibit deformation, and at the same time maintain the overall conductivity.

[0086] Conversely, if a target metal or a target metal oxide with better ductility than aluminum is used in the composite aluminum layer, it is necessary to increase the content of this target metal or this target metal oxide in the edge area of the composite current collector 1000 and decrease the content of this target metal or this target metal oxide in the center area of the composite current collector 1000.

[0087] In some embodiments, when the composite aluminum layer is composed of aluminum and a target metal, the target metal includes one or more of copper, nickel, or zinc; or, the target metal includes silver. When the composite aluminum layer is composed of aluminum and a target metal oxide, the target metal oxide includes aluminum oxide. The multiple material selection improves the flexibility of the solution and is compatible with different types of composite current collectors.

[0088] Specifically, in some embodiments, when the composite aluminum layer is composed of aluminum and a target metal, and the target metal includes one or more of copper, nickel, or zinc, the ductility of copper is greater than that of aluminum, the ductility of nickel is greater than that of aluminum, and the ductility of zinc is greater than that of aluminum. The ductility of the target metal is greater than that of aluminum, and the content of the target metal or the target metal oxide decreases in the direction from the edge of the composite current collector 1000 to the center of the composite current collector 1000.

[0089] In some embodiments, when the composite aluminum layer is composed of aluminum and a target metal, and the target metal includes silver, the ductility of silver is greater than that of aluminum. The ductility of the target metal is greater than that of aluminum, and the content of the target metal or the target metal oxide decreases in the direction from the edge of the composite current collector 1000 to the center of the composite current collector 1000.

[0090] In some embodiments, when the composite aluminum layer is composed of aluminum and a target metal oxide, and the target metal oxide includes aluminum oxide, the ductility of aluminum oxide is less than that of aluminum, the ductility of the target metal is less than that of aluminum, and the content of the target metal or the target metal oxide increases in the direction from the edge of the composite current collector 1000 to the center of the composite current collector 1000. Specifically, during the evaporation process, oxygen is introduced into the corresponding area of the anti-wrinkle structure 500 through the gas supply channel, and the oxygen content provided by the gas supply channel in the outer area (the area close to the edge of the composite current collector 1000) of the corresponding anti-wrinkle structure 500 is lower than the oxygen content provided by the gas supply channel in the inner area (the area close to the center of the composite current collector 1000) of the anti-wrinkle structure 500.

[0091] In some embodiments, the oxygen flow rate provided by the gas supply channel corresponding to the outer area of the anti-wrinkle structure 500 is 80 sccm - 120 sccm; the oxygen flow rate provided by the gas supply channel corresponding to the inner area of the anti-wrinkle structure 500 is 150 sccm - 300 sccm.

[0092] In some embodiments, the oxygen flow rate provided by the gas supply channel corresponding to the inner area of the anti-wrinkle structure 500 can be 1.2 times - 4 times that of the oxygen flow rate provided by the gas supply channel corresponding to the outer area of the anti-wrinkle structure 500.

[0093] Preferably, the first conductive layer 200 and the second conductive layer 300 of the flat section 400 include a bonding layer made of aluminum oxide provided on the base film 100 and a conductive aluminum layer on the bonding layer. The bonding layer can enhance the bonding force between the conductive aluminum layer and the base film 1000 in the composite current collector 1000. At the same time, there is a certain bonding force between the anti-wrinkle structure of aluminum oxide and the edge of the bonding layer made of aluminum oxide material, which can prevent the composite aluminum layer on the anti-wrinkle structure 500 from falling off.

[0094] Referring to Figure 4 , at least one embodiment of the present application proposes a method for preparing a composite current collector 1000, and the method for preparing the composite current collector 1000 includes the following steps:

[0095] Step S100, prepare the composite current collector 1000, such that the composite current collector 1000 includes a flat section 400 formed along a first direction and a wrinkle prevention structure 500; the wrinkle prevention structure 500 includes at least one shaped fold.

[0096] According to the method for preparing the composite current collector 1000 of the embodiment of the present application, by parameter coordination to actively induce the formation of folds, during the handling and packaging process of the finished roll of the composite current collector 1000 formed after winding, when the end face of the finished roll of the composite current collector 1000 is subjected to a longitudinal thrust and a lateral thrust, the wrinkle prevention structure 500 folds preferentially to form a barrier, effectively preventing the folds from spreading to other parts of the composite current collector 1000. High-precision and low-cost wrinkle management is achieved. Subsequently, the wrinkle prevention structure 500 can be cut off before battery processing, improving the yield.

[0097] In some embodiments, the composite current collector 1000 includes a base film 100, and a first conductive layer 200 and a second conductive layer 300 respectively disposed on both sides of the base film 100. Refer to Figure 5 and Figure 6 , in the method for preparing the composite current collector 1000 provided by the embodiment of the present application, step S100, prepare the composite current collector 1000, specifically including:

[0098] Step S110, provide the base film 100;

[0099] Step S120, place the base film 100 on the unwinding side of the machine table, such that the base film 100 sequentially passes through an unwinding roller 2000, a guiding roller 3000, a first main drum 4000, and a second main drum 5000 along a preset film passing route, so as to form a first conductive layer 200 by evaporation plating on the first side of the base film 100 through an evaporation boat disposed on the first main drum 4000, and form a second conductive layer 300 by evaporation plating on the second side of the base film 100 through an evaporation boat disposed on the second main drum 5000;

[0100] Wherein, the wrinkle prevention structure 500 is formed during the process of evaporation plating to form the first conductive layer 200 and / or the second conductive layer 300.

[0101] Specifically, the evaporation boat located below the first main drum 4000 is a first evaporation boat 4100, and the evaporation boat located below the second main drum 5000 is a second evaporation boat 5100. After the composite current collector 1000 is prepared, it is wound at a winding roller 9000.

[0102] Through the above steps, the evaporation plating solution in the evaporation boat vaporizes and deposits on the surface of the base film 100 to form the first conductive layer 200 and / or the second conductive layer 300. During the evaporation plating process, the wrinkle prevention structure 500 is simultaneously formed.

[0103] In some embodiments, the number of evaporation boats disposed at the first main drum 4000 and the second main drum 5000 is multiple. Specifically, the multiple evaporation boats below the first main drum 4000 are arranged along the first direction; the multiple evaporation boats below the second main drum 5000 are arranged along the first direction. Both the first conductive layer 200 and the second conductive layer 300 include a composite aluminum layer composed of aluminum and a target metal, or composed of aluminum and a target metal oxide.

[0104] Among them, preparing the composite current collector 1000 further includes the following steps:

[0105] Before forming the first conductive layer 200 and the second conductive layer 300, for the evaporation boat used to form the anti-wrinkle structure 500, along the direction from the edge of the composite current collector 1000 pointing to the center of the composite current collector 1000, adjust to increase the content of the target metal or the target metal oxide in the evaporation boat.

[0106] Through the above steps, the ductility of the anti-wrinkle structure 500 is reduced along the direction from the edge of the composite current collector 1000 to the center of the composite current collector 1000. That is, in the composite current collector 1000 prepared by the above steps, the anti-wrinkle structure 500 near the edge of the composite current collector 1000 has higher ductility. During the handling and packaging process of the finished roll of the composite current collector 1000, when the end face at the edge of the composite current collector 1000 is subjected to longitudinal thrust and lateral thrust, the wrinkles of the anti-wrinkle structure 500 are more likely to form on the outside, reducing the possibility of the wrinkles spreading to the middle.

[0107] In some embodiments, adjusting the content of the target metal or the target metal oxide in the evaporation boat specifically includes the following steps:

[0108] When the target metal is one or more of copper, nickel, or zinc, in the evaporation boat corresponding to the area of the anti-wrinkle structure 500 near the edge of the composite current collector 1000, the mass ratio range of aluminum to the target metal is 1:2 - 1:4; in the evaporation boat corresponding to the area of the anti-wrinkle structure 500 near the center of the composite current collector 1000, the mass ratio range of aluminum to the target metal is 1:7 - 1:10.

[0109] In some embodiments, when the target metal is one or more of copper, nickel, or zinc, in the evaporation boat corresponding to the area of the anti-wrinkle structure 500 near the edge of the composite current collector 1000, the mass ratio of aluminum to the target metal is 1:3; in the evaporation boat corresponding to the area of the anti-wrinkle structure 500 near the center of the composite current collector 1000, the mass ratio of aluminum to the target metal is 1:9.

[0110] In some embodiments, adjusting the content of the target metal or target metal oxide in the evaporation boat specifically includes the following steps: When the target metal is silver, in the evaporation boat in the area where the anti-wrinkle structure 500 is close to the edge of the composite current collector 1000, the mass ratio range of aluminum to silver is 1:6 - 1:9; in the evaporation boat in the area where the anti-wrinkle structure 500 is close to the center of the composite current collector 1000, the mass ratio range of aluminum to silver is 1:3 - 1:5.

[0111] In some embodiments, when the target metal is silver, in the evaporation boat in the area where the anti-wrinkle structure 500 is close to the edge of the composite current collector 1000, the mass ratio of aluminum to silver is 1:8; in the evaporation boat in the area where the anti-wrinkle structure 500 is close to the center of the composite current collector 1000, the mass ratio of aluminum to silver is 1:4.

[0112] In some embodiments, adjusting the content of the target metal or target metal oxide in the evaporation boat specifically includes the following steps: When the target metal is aluminum oxide, the oxygen content introduced at the evaporation boat in the area where the anti-wrinkle structure 500 is close to the edge of the composite current collector 1000 is lower than the oxygen content introduced at the evaporation boat in the area where the anti-wrinkle structure 500 is close to the center of the composite current collector 1000.

[0113] In some embodiments, during the evaporation coating process, oxygen is introduced into the corresponding area of the anti-wrinkle structure 500 through the gas supply channel, and the oxygen content provided by the gas supply channel in the outer area of the anti-wrinkle structure 500 (the area close to the edge of the composite current collector 1000) is lower than the oxygen content provided by the gas supply channel in the inner area of the anti-wrinkle structure 500 (the area close to the center of the composite current collector 1000).

[0114] In some embodiments, the oxygen flow rate provided by the gas supply channel in the outer area of the anti-wrinkle structure 500 is 80 sccm - 120 sccm; the oxygen flow rate provided by the gas supply channel in the inner area of the anti-wrinkle structure 500 is 150 sccm - 300 sccm.

[0115] In some embodiments, the oxygen flow rate provided by the gas supply channel in the inner area of the anti-wrinkle structure 500 can be 1.2 times - 4 times that of the oxygen flow rate provided by the gas supply channel in the outer area of the anti-wrinkle structure 500.

[0116] In some embodiments, preparing the composite current collector 1000 further includes the following steps:

[0117] Before forming the first conductive layer 200, the base film 100 is flattened by the unwinding flattening roller set; between the first main drum 4000 and the second main drum 5000, the base film 100 is flattened by the transition flattening roller set; after forming the second conductive layer 300, the base film 100 is flattened by the winding flattening roller set; wherein, the wrap angles of the transition flattening roller set and the winding flattening roller set are both smaller than the wrap angle of the unwinding flattening roller set, that is, the flattening forces of the transition flattening roller set and the winding flattening roller set on the base film are smaller, so that wrinkles are gradually formed at both ends during the movement of the base film 100 to form an anti-wrinkle structure with shaped wrinkles.

[0118] It can be understood that the unwinding flattening roller set includes one or more unwinding flattening rollers. Specifically, in some embodiments, the unwinding flattening roller set sequentially includes a first unwinding flattening roller 6000 and a second unwinding flattening roller 6100 along the movement direction of the base film 100, which are used to flatten the base film 100 and prepare for the base film 100 to enter the first main drum 4000.

[0119] It can be understood that the transition flattening roller set includes one or more transition flattening rollers. Specifically, in some embodiments, the transition flattening roller set sequentially includes a first transition flattening roller 7000 and a second transition flattening roller 7100 along the movement direction of the base film 100, and the wrap angle of the second transition flattening roller 7100 is larger than that of the first transition flattening roller 7000. The second transition flattening roller 7100 is the flattening roller before entering the second main drum 5000. The wrap angle of the second transition flattening roller 7100 is set to be larger to avoid excessive wrinkling of the base film 100 and affecting the coating uniformity at the second main drum 5000.

[0120] Furthermore, in some embodiments, the transition flattening roller set further includes a third transition flattening roller 7200 disposed between the first transition flattening roller 7000 and the second transition flattening roller 7100 to further improve the flattening effect.

[0121] In some embodiments, the winding flattening roller set includes one or more winding flattening rollers. Specifically, in some embodiments, the winding flattening roller set sequentially includes a first winding flattening roller 8000 and a second winding flattening roller 8100 along the movement direction of the base film 100, which are used to flatten the base film 100 and prepare for winding.

[0122] In some embodiments, the wrap angles of each flattening roller are set as follows:

[0123] In the unwinding flattening roller set, the wrap angle of the first unwinding flattening roller 6000 is 15° - 20°, and the wrap angle of the second unwinding flattening roller 6100 is 15° - 20°;

[0124] In the transition flattening roller group, the wrap angle of the first transition flattening roller 7000 is 5° - 10°, the wrap angle of the third transition flattening roller 7200 is 5° - 10°, and the wrap angle of the second transition flattening roller 7100 is 7° - 12°;

[0125] In the winding flattening roller, the wrap angle of the first winding flattening roller 8000 is 5° - 10°, and the wrap angle of the second winding flattening roller 8100 is 5° - 10°. Place the base film 100 on the unwind side of the machine table, and make the base film 100 pass through the unwind roller 2000, the guide roller 3000, the unwind flattening roller group, the first main drum 4000, the transition flattening roller group, the second main drum 5000, the winding flattening roller group, and the winding roller 9000 in sequence along the preset film threading route.

[0126] In some embodiments, preparing the composite current collector 1000 further includes the following steps:

[0127] During the evaporation process of forming the first conductive layer 200 and / or the second conductive layer 300, adjust the evaporation power of the evaporation equipment to the first power to form the anti-wrinkle structure 500; adjust the evaporation power of the evaporation equipment to the second power to form the flat section 400;

[0128] Wherein, the first power is greater than or equal to the thermal damage power of the base film 100;

[0129] The second power is less than the thermal damage power of the base film 100;

[0130] The thermal damage power is configured to enable the base film 100 to generate thermal damage to form a shaped wrinkle.

[0131] Specifically, when the evaporation power of the evaporation equipment is the first power, the base film 100 forms thermal damage to form a shaped wrinkle 510. When the evaporation power is the second power, no thermal damage is formed, thus forming the flat section 400. By controlling the local heat input with different powers, the anti-wrinkle structure 500 is deformed in a controlled manner, and the flat section 400 remains intact.

[0132] The evaporation power described in this application is the power supplied to the evaporation boat in the evaporation equipment. The evaporation equipment has multiple evaporation boats, and the evaporation equipment can independently control the evaporation power of each evaporation boat.

[0133] In some embodiments, when the thermal damage power of the base film 100 is configured to be 7.6 KW, the base film 100 can generate thermal damage. When the first power is greater than or equal to 7.6 KW, such as when the first power is adjusted to 7.6 KW, the base film 100 will generate thermal damage. When the second power is less than 7.6 KW, such as when the second power is adjusted to 7.2 KW, the base film 100 will not generate thermal damage.

[0134] In some embodiments, preparing the composite current collector 1000 further includes the following steps:

[0135] Before the base film 100 passes through the first main drum 4000 and the second main drum 5000, a heat insulation layer is formed in the areas of the first main drum 4000 and the second main drum 5000 corresponding to the anti-wrinkle structure 500. The heat insulation layer can prevent the film surface from being in close contact with the main drum, reduce the cooling effect of the main drum on the anti-wrinkle structure 500, thereby forming thermal damage, and causing the film to deform to form the shaped anti-wrinkle structure 500.

[0136] In some embodiments, the heat insulation layer is configured as a high-temperature tape wound around the first main drum 4000 and the second main drum 5000, and the thickness of the high-temperature tape is 0.2 mm - 1 mm. The width of the high-temperature tape in the first direction is less than the width of the anti-wrinkle structure 500 in the first direction. The high-temperature tape is easy to peel off and has a high heat insulation effect, which is convenient for maintenance and use. It can be understood that the heat insulation layer can also be configured as a ceramic coating or a polymer film, etc.

[0137] In some embodiments, the thickness of the heat insulation layer on the first main drum 4000 is less than the thickness of the heat insulation layer on the second main drum 5000. This can avoid the excessive wrinkling phenomenon on the first main drum 4000, which affects the evaporation uniformity when evaporating the other side.

[0138] In an embodiment provided by the present application, the preparation method of the composite current collector 1000 is as follows:

[0139] Place the PET base film 100 on the unwind side of the machine table, and sequentially pass through the unwind roller 2000, the guide roller 3000, the unwind flattening roller group, the first main drum 4000, the transition flattening roller group, the second main drum 5000, and the winding flattening roller group according to a predetermined film threading route. Finally, wind the plated composite aluminum composite current collector 1000 on the winding roller 9000; wherein, a plurality of evaporation boats arranged along the first direction of the base film 100 are respectively provided at the first main drum 4000 and the second main drum 5000. The aluminum wire is sent to the upper part of the evaporation boat through the wire feeding system, melts under the high heat of the evaporation boat and then falls into the evaporation boat. The aluminum liquid in the evaporation boat vaporizes and is deposited on the surface of the base film 100;

[0140] After the machine table is closed, set the wrap angles of the flattening rollers and the film in sequence: in the unwind flattening roller group, the wrap angle of the first unwind flattening roller 6000 is 15° - 20°, and the wrap angle of the second unwind flattening roller 6100 is 15° - 20°; in the transition flattening roller group, the wrap angle of the first transition flattening roller 7000 is 5° - 10°, the wrap angle of the third transition flattening roller 7200 is 5° - 10°, and the wrap angle of the second transition flattening roller 7100 is 7° - 12°; in the winding flattening roller, the wrap angle of the first winding flattening roller 8000 is 5° - 10°, and the wrap angle of the second winding flattening roller 8100 is 5° - 10°.

[0141] Before the start of evaporation coating, set the main drum temperature as follows: for the first main drum 4000, it is -10°C - 5°C; for the second main drum 4000, it is -15°C - 10°C. After the start of evaporation coating, adjust the evaporation coating power to 5.6 KW - 7.6 KW and adjust the wire feeding speed to 3 m / min - 30 m / min. Among them, the evaporation power of the evaporation boat in the area corresponding to the anti-wrinkle structure 500 is 7.6 KW, so that the PET base film 100 at the corresponding position of the wrinkle structure is thermally damaged during the evaporation coating process; the evaporation power of the evaporation boat in the area corresponding to the flat section 400 is 7.2 KW, ensuring that the PET base film 100 at the corresponding position of the flat section 400 is not thermally damaged.

[0142] The composite current collector 1000 and its preparation method in the embodiments of the present application are different from the traditional methods of passive response to wrinkles. By actively designing the wrinkle area to form a physical barrier, the expansion of wrinkles is significantly inhibited. It can improve the inclusiveness of the base film 100. Even if there are slight defects in the appearance state of the PET base film 100, it does not affect the production yield of the composite aluminum foil.

[0143] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of 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, it should be considered as the scope described in this specification.

[0144] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A composite current collector, comprising a base film and a first conductive layer and a second conductive layer respectively disposed on both sides of the base film, characterized in that: The composite current collector includes a flat section arranged along a first direction and at least one anti-wrinkle structure, wherein the anti-wrinkle structure includes at least one shaped fold.

2. The composite current collector according to claim 1, characterized in that: The shaped pleats extend along a second direction; the second direction intersects the first direction.

3. The composite current collector according to claim 2, characterized in that: The anti-wrinkle structure is provided at both ends of the composite current collector along the first direction; the value range of the angle between the second direction and the first direction facing the anti-wrinkle structure includes: 45°-90°; And / or, the anti-wrinkle structure comprises a plurality of shaped folds; the shaped folds in the same anti-wrinkle structure are parallel to each other; And / or, the anti-wrinkle structures are provided at both ends of the composite current collector along the first direction; the two anti-wrinkle structures are symmetrically arranged with the center line of the composite current collector extending along the third direction as the symmetry center; and the third direction is perpendicular to the first direction.

4. The composite current collector according to claim 1, characterized in that: The composite current collector includes a transition section located between the anti-wrinkle structure and the flattening section and connecting the flattening section and the anti-wrinkle structure; Further, the material of the transition section includes one or more of copper, nickel or zinc; and / or the width of the transition section in the first direction is 20 mm-70 mm.

5. The composite current collector according to any one of claims 1 to 4, characterized in that: The ratio between the width of the anti-wrinkle structure in the first direction and the width of the flattening section in the first direction is 1:2-1:16; And / or, the anti-wrinkle structure is arranged at the edge of the composite current collector, and the distance between the side of the anti-wrinkle structure close to the center of the composite current collector in the first direction and the corresponding end surface of the composite current collector is 10mm-300mm.

6. The composite current collector according to any one of claims 1 to 4, characterized in that: The ductility of the anti-wrinkle structure decreases along a direction from an edge of the composite current collector toward a center of the composite current collector.

7. The composite current collector according to claim 6, characterized in that: The first conductive layer and the second conductive layer at the anti-wrinkle structure both include a composite aluminum layer consisting of aluminum and a target metal, or aluminum and a target metal oxide; Among them, in the composite aluminum layer located in the area where the anti-wrinkle structure is located, the ductility of the target metal or the target metal oxide is less than that of aluminum, and the content of the target metal or the target metal oxide increases along the direction from the edge of the composite current collector to the center of the composite current collector; or, the ductility of the target metal or the target metal oxide is greater than that of aluminum, and the content of the target metal or the target metal oxide decreases along the direction from the edge of the composite current collector to the center of the composite current collector.

8. The composite current collector according to claim 7, characterized in that: When the composite aluminum layer is composed of aluminum and a target metal, the target metal includes one or more of copper, nickel or zinc; or the target metal includes silver; When the composite aluminum layer is composed of aluminum and a target metal oxide, the target metal oxide includes aluminum oxide.

9. A method for preparing a composite current collector, characterized in that: The following steps are involved: A composite current collector is prepared, so that the composite current collector includes a flat section and an anti-wrinkle structure formed along a first direction; the anti-wrinkle structure includes at least one shaped fold.

10. The method for preparing a composite current collector according to claim 9, characterized in that: The composite current collector comprises a base film and a first conductive layer and a second conductive layer respectively arranged on both sides of the base film; wherein the preparation of the composite current collector comprises: providing the base film; The base film is placed on the unwinding side of the machine, and the base film is passed through the unwinding roller, the guide roller, the first main drum and the second main drum in sequence along a preset film-passing route, so that the first conductive layer is formed by evaporation deposition on the first side of the base film by an evaporation boat arranged on the first main drum, and the second conductive layer is formed by evaporation deposition on the second side of the base film by an evaporation boat arranged on the second main drum; The anti-wrinkle structure is formed in the process of forming the first conductive layer and / or the second conductive layer by evaporation.

11. The method for preparing a composite current collector according to claim 10, characterized in that: The number of the evaporation boats disposed at the first main drum and the second main drum is multiple; the first conductive layer and the second conductive layer both include a composite aluminum layer composed of aluminum and a target metal, or aluminum and a target metal oxide; wherein the preparation of the composite current collector further includes: Before forming the first conductive layer and the second conductive layer, for the evaporation boat used to form the anti-wrinkle structure, the content of the target metal or the target metal oxide in the evaporation boat is adjusted to increase along a direction from the edge of the composite current collector to the center of the composite current collector.

12. The method for preparing a composite current collector according to claim 11, characterized in that: Adjusting the content of the target metal or the target metal oxide in the evaporation boat comprises: When the target metal is one or more of copper, nickel or zinc, the mass ratio of aluminum to the target metal in the evaporation boat corresponding to the area of ​​the anti-wrinkle structure close to the edge of the composite current collector is in the range of 1:2-1:4; the mass ratio of aluminum to the target metal in the evaporation boat corresponding to the area of ​​the anti-wrinkle structure close to the center of the composite current collector is in the range of 1:7-1:10; When the target metal is silver, the mass ratio of aluminum to silver in the evaporation boat corresponding to the area of ​​the anti-wrinkle structure close to the edge of the composite current collector is in the range of 1:6-1:9; the mass ratio of aluminum to silver in the evaporation boat corresponding to the area of ​​the anti-wrinkle structure close to the center of the composite current collector is in the range of 1:3-1:5; When the target metal is aluminum oxide, the oxygen content introduced into the evaporation boat corresponding to the area of ​​the anti-wrinkle structure close to the edge of the composite current collector is lower than the oxygen content introduced into the evaporation boat corresponding to the area of ​​the anti-wrinkle structure close to the center of the composite current collector.

13. The method for preparing a composite current collector according to claim 10, characterized in that: The preparation The composite current collector further comprises: Before forming the first conductive layer, the base film is flattened by an unwinding flattening roller group; between the first main drum and the second main drum, the base film is flattened by a transition flattening roller group; after forming the second conductive layer, the base film is flattened by a winding flattening roller group; wherein the wrap angles of the transition flattening roller group and the winding flattening roller group are both smaller than the wrap angle of the unwinding flattening roller group; The transition flattening roller group includes a first transition flattening roller and a second transition flattening roller in sequence along the moving direction of the base film, and the wrap angle of the second transition flattening roller is greater than the wrap angle of the first transition flattening roller.

14. The method for preparing a composite current collector according to any one of claims 10 to 13, characterized in that: The preparation of the composite current collector further comprises: During the process of forming the first conductive layer and / or the second conductive layer by evaporation, adjusting the evaporation power of the evaporation device to the first power to form the anti-wrinkle structure; adjusting the evaporation power of the evaporation device to the second power to form the flattening section; Wherein, the first power is greater than or equal to the basement membrane thermal damage power; The second power is less than the basement membrane thermal damage power; The thermal damage power is configured to cause thermal damage to the base film to form the shaped wrinkles.

15. The method for preparing a composite current collector according to claim 14, characterized in that: The preparation of the composite current collector further comprises: Before the base film passes through the first main drum and the second main drum, a heat insulation layer is formed on the areas of the first main drum and the second main drum corresponding to the anti-wrinkle structure; The thickness of the heat insulation layer on the first main drum is smaller than the thickness of the heat insulation layer on the second main drum.

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