A full-metal tab composite current collector and a preparation method thereof

Abstract

The application provides a full-metal tab composite current collector and a preparation method thereof, and belongs to the technical field of composite current collector manufacturing. The preparation method of the full-metal tab composite current collector comprises the following steps: forming a first metal layer on one side surface of a polymer base material, and in the width direction, the two ends of the polymer base material and the first metal layer are flush; removing the regions at the two ends of the polymer base material in the width direction, so that the first metal layer is exposed from the two ends of the polymer base material; forming a second metal layer on the other side surface of the polymer base material, the two end surfaces of the polymer base material in the width direction, and the surface of the first metal layer exposed region, so as to form full-metal tabs at the two ends of the polymer base material in the width direction. The preparation method can effectively solve the problems of easy bursting of the composite current collector during the winding process under the pre-process of the welding process and the limitation of the industrialized manufacturing of the ultra-thin composite current collector.

Description

Technical Field

[0001] This application relates to the field of composite current collector manufacturing technology, and more specifically, to a composite current collector with all-metal tabs and its preparation method. Background Technology

[0002] Composite current collectors have the advantages of high energy density and low cost. They have a "sandwich" structure (i.e., metal layer - polymer substrate film layer - metal layer). Since the polymer substrate layer in the middle is an insulating material and cannot be directly welded, the tab welding of composite current collectors usually requires the use of transfer welding, which increases the manufacturing cost of the cell unit. In addition, transfer welding also has the problems of low welding efficiency and low welding strength.

[0003] To address the issue of transition welding required for composite current collectors, patent document CN 120376653 A discloses a method that involves welding the substrate to pure copper foil tabs before copper plating, reducing the need for separate tab welding. Compared to traditional composite copper foil (which requires transition welding), this eliminates the need for separate tab welding by the client, saving subsequent manufacturing costs and improving efficiency. However, because the tab welding process is prioritized, the resulting composite current collector has a relatively large total thickness in the tab area (i.e., the total thickness of the polymer substrate layer and the metal layers on either side). This can lead to rib bursting during winding due to the accumulated thickness in the tab area. Furthermore, as composite current collectors evolve towards ultra-thin designs, the thickness of the polymer substrate is decreasing from 4.5 μm to 3 μm or even 2 μm. Consequently, the pure copper foil tabs used for welding also need to be thinner. However, industrial production technology for ultra-thin metal layers is not yet widespread, severely restricting the promotion and application of ultra-thin composite current collectors with a pre-welding process (especially at the industrial manufacturing level).

[0004] Therefore, for composite current collectors with welding as a pre-process, there is an urgent need for a new manufacturing process to simultaneously solve the problems of easy bursting during the winding process and the limitations of industrial manufacturing of ultra-thin composite current collectors. Summary of the Invention

[0005] The purpose of this application is to provide a composite current collector with all-metal tabs and its preparation method. This preparation method can effectively solve the problems of easy bursting of composite current collectors during the winding process under the pre-welding process and the limitations of industrial manufacturing of ultra-thin composite current collectors.

[0006] The embodiments of this application are implemented as follows: In a first aspect, embodiments of this application provide a method for preparing a composite current collector with all-metal tabs, comprising the following steps: forming a first metal layer on one side surface of a polymer substrate, wherein the ends of the polymer substrate and the first metal layer are flush in the width direction; removing the regions at both ends of the polymer substrate along the width direction to expose the first metal layer from both ends of the polymer substrate; forming a second metal layer on the other side surface of the polymer substrate, the two end surfaces of the polymer substrate along the width direction, and the surface of the exposed region of the first metal layer, to form all-metal tabs at both ends of the polymer substrate along the width direction.

[0007] In the above technical solution, a first metal layer with adjustable thickness is first formed on one side of the polymer substrate. Then, the polymer substrate at both ends is removed to expose the first metal layer in the corresponding areas. A second metal layer with adjustable thickness can then be formed according to actual needs. The first and second metal layers, located at both ends of the polymer substrate in the width direction and bonded together, constitute an all-metal tab, which can then be directly used for welding with an external tab. This fabrication process forms a composite current collector. Because the polymer substrate in the tab area (which accounts for the largest proportion of thickness in the composite current collector) is removed in advance (existing processes do not remove it), the total thickness of the tab area can be effectively reduced, thus effectively solving the problem of easy bursting of composite current collectors during the winding process under the pre-welding process. Simultaneously, since the thickness of both the first and second metal layers can be flexibly adjusted according to actual needs and is not limited by the thickness of the incoming metal layer material, ultra-thin composite current collectors can be achieved and industrial manufacturing is possible. Therefore, the fabrication method provided in this application can effectively solve the problems of easy bursting of composite current collectors during the winding process under the pre-welding process and the limitations on the industrial manufacturing of ultra-thin composite current collectors.

[0008] In some alternative embodiments, the thickness of the first metal layer is less than the thickness of the second metal layer. After the all-metal tab is formed, a third metal layer is formed on the side of the first metal layer facing away from the polymer substrate, and the sum of the thicknesses of the first metal layer and the third metal layer is the same as the thickness of the second metal layer.

[0009] In the above technical solution, the metal layer on the first side of the composite current collector is composed of a first metal layer and a third metal layer, and the metal layer on the second side is a second metal layer. This is equivalent to the metal layer on the first side being prepared by a stepwise method. The advantage of this process is that it can effectively solve the problem that after the formation of the first metal layer, the corresponding membrane material is prone to edge curling during subsequent transportation, transfer or temporary storage, which can lead to membrane material damage or reduced mechanical properties.

[0010] In some alternative implementations, the thickness of the first metal layer is 80 nm to 120 nm, or / and the thickness of the second metal layer is 0.5 μm to 1.5 μm.

[0011] In the above technical solution, limiting the thickness of the first metal layer within the aforementioned range ensures a suitable thickness. This effectively mitigates the problem of edge curling in the corresponding film material after the first metal layer is formed. Furthermore, it serves as a good substrate for the subsequent formation of the second metal layer. It also offers the advantage of being less prone to damage or breakage during transport or transfer. Limiting the thickness of the second metal layer within the aforementioned range results in a thinner metal layer on one side of the composite current collector with a suitable dimensional range. This leads to superior electrical and mechanical properties, aligning well with the development trend of ultra-thin composite current collectors and demonstrating promising application prospects.

[0012] In some alternative implementations, the total thickness of the first metal layer, the second metal layer, and the third metal layer is not greater than the thickness of the polymer substrate.

[0013] In the above technical solution, the total thickness of the metal layer is controlled to be no greater than the thickness of the polymer substrate. That is, the total thickness of the composite current collector in the tab area (without the polymer substrate, the total thickness is equal to the total thickness of the metal layer) is no greater than the thickness of the polymer substrate. This setting can better solve the problem of the composite current collector being prone to bursting during the winding process under the pre-welding process.

[0014] In some alternative implementations, both the second and third metal layers are prepared using magnetron sputtering deposition technology.

[0015] Among the above technical solutions, magnetron sputtering coating technology has the advantages of high deposition efficiency, low substrate temperature, wide applicability, stable process and environmental protection and economy. At the same time, the metal layer formed by this coating technology has the advantages of being dense and uniform, high in purity and having a relatively strong bond with the polymer substrate.

[0016] In some alternative implementations, the steps of forming the second metal layer and forming the third metal layer are performed sequentially in the same magnetron sputtering apparatus.

[0017] In the above technical solution, the second metal layer and the third metal layer are processed sequentially in the same magnetron sputtering equipment, that is, the interval between the preparation of the second metal layer and the preparation of the third metal layer is short. After the second metal layer is formed, the problem of film material curling caused by the thickness difference between the second metal layer and the first metal layer can be effectively improved.

[0018] In some alternative embodiments, after the regions at both ends of the polymer substrate are removed, both ends of the polymer substrate have a gradient section in the width direction, and the thickness of the gradient section gradually increases from the outside to the inside.

[0019] In the above technical solution, the two ends of the polymer substrate are removed according to the above standard. Specifically, both ends of the polymer substrate along the width direction have a gradually increasing thickness section from the outside to the inside. That is, both ends of the polymer substrate are inclined planes. In the subsequent step of forming the second metal layer, this type of end face has the advantage of facilitating the preparation of the second metal layer. At the same time, it also makes the formed second metal layer have the advantage of having a relatively uniform overall thickness.

[0020] In some alternative embodiments, the exposed areas of the first metal layer at both ends are 20 mm to 40 mm in the width direction; or / and the thickness of the polymer substrate is 2 μm to 6 μm, and the size of a single gradient segment is 0.5 mm to 5 mm in the width direction.

[0021] In the above technical solution, the width of the exposed area of ​​the first metal layer is limited to the aforementioned range so that the subsequently formed all-metal tab area has a suitable width, thereby facilitating direct welding with the external tab. When the thickness of the polymer substrate is within the aforementioned range, the width of each gradient segment is also limited to the aforementioned range so that the gradient segment has a suitable tilt angle. In the subsequent step of forming the second metal layer, this type of end face has the advantage of facilitating the fabrication of the second metal layer, and at the same time, it also has the advantage of making the formed second metal layer have a relatively uniform overall thickness.

[0022] In some alternative implementations, laser etching is used to remove the regions at both ends of the polymer substrate.

[0023] In the above technical solution, laser etching technology is used to remove the two ends of the polymer substrate, which has the advantages of high removal precision, no pollution, small heat-affected zone and high removal efficiency.

[0024] In some alternative implementations, the laser is a carbon dioxide laser.

[0025] In the above technical solution, the carbon dioxide laser is characterized by its ability to selectively etch and remove the polymer substrate on the surface of the metal layer, thereby efficiently and thoroughly removing the regions at both ends of the polymer substrate while effectively protecting the metal layer.

[0026] In some alternative embodiments, the polymer substrate is selected from at least one of BOPP, BOPET, BOPI and BOPE, and / or the laser wavelength is 10.6 μm and the laser output power is 3 W to 5 W.

[0027] In the above technical solution, the polymer substrate selected has advantages such as good mechanical properties and heat resistance. Furthermore, the polymer substrate is applicable to a wide variety of types, providing numerous feasible solutions. By limiting the wavelength and output power of the laser (i.e., the actual power applied to the polymer substrate) within the aforementioned ranges, the selectivity of the laser on the polymer substrate becomes more precise, thereby enabling more efficient and thorough removal of the regions at both ends of the polymer substrate while effectively protecting the metal layer.

[0028] Secondly, embodiments of this application provide a composite current collector, which is prepared using the preparation method provided in the first aspect embodiment.

[0029] In the above technical solution, the composite current collector is prepared by the preparation method provided in the first aspect embodiment. Its tab area is all metal, so that it can be directly welded to the external tab. Compared with conventional composite current collectors (which require transfer welding), it has the advantages of high welding efficiency and more reliable welding. At the same time, since there is no polymer substrate at both ends of its width direction (i.e., at the tab), it can effectively solve the problem of easy bursting during the winding process. In addition, the metal layer of the composite current collector has the advantage of flexible thickness adjustment, which facilitates the realization of ultra-thinness. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A process flow diagram illustrating a method for preparing an all-metal tab composite current collector according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure after the first metal layer is formed on one side of the polymer substrate; Figure 3 To be Figure 2 A schematic diagram of the structure after the two ends of the polymer substrate are removed; Figure 4 In order to be in Figure 3 A schematic diagram of the structure after the second and third metal layers are formed on the membrane material.

[0032] Icons: 10-Composite current collector; 11-Electrode region; 100-Polymer substrate; 200-First metal layer; 300-Second metal layer; 400-Third metal layer; a-Width direction. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0034] It should be noted that the terms "and / or" in this application, such as "feature 1 and / or feature 2", all refer to the three cases of "feature 1" alone, "feature 2" alone, and "feature 1" plus "feature 2".

[0035] In addition, in the description of this application, unless otherwise stated, "one or more" means two or more; the range of "numerical value a to numerical value b" includes the two endpoints "a" and "b"; and "unit of measurement" in "numerical value a to numerical value b + unit of measurement" represents the "unit of measurement" of both "numerical value a" and "numerical value b".

[0036] The following is a detailed description of a composite current collector with an all-metal tab according to an embodiment of this application and its preparation method.

[0037] In a first aspect, embodiments of this application provide a method for preparing a composite current collector with all-metal tabs, comprising the following steps: forming a first metal layer on one side surface of a polymer substrate, wherein the ends of the polymer substrate and the first metal layer are flush in the width direction; removing the regions at both ends of the polymer substrate along the width direction to expose the first metal layer from both ends of the polymer substrate; forming a second metal layer on the other side surface of the polymer substrate, the two end surfaces of the polymer substrate along the width direction, and the surface of the exposed region of the first metal layer, to form all-metal tabs at both ends of the polymer substrate along the width direction.

[0038] In this application, a first metal layer with adjustable thickness is first formed on one side of a polymer substrate. Then, the polymer substrate at both ends is removed to expose the first metal layer in the corresponding areas. A second metal layer with adjustable thickness can then be formed as needed. The first and second metal layers, located at both ends of the polymer substrate in the width direction and bonded together, constitute an all-metal tab, which can then be directly used for welding with an external tab. This fabrication process forms a composite current collector. Because the polymer substrate in the tab area (which accounts for the largest proportion of thickness in the composite current collector) is removed beforehand (unlike in existing processes), the total thickness of the tab area is effectively reduced, thus effectively solving the problem of easy bursting of composite current collectors during the winding process in pre-welding processes. Simultaneously, since the thickness of both the first and second metal layers can be flexibly adjusted according to actual needs and is not limited by the thickness of the incoming metal layer material, ultra-thin composite current collectors can be achieved and industrial manufacturing is possible. Therefore, the fabrication method provided in this application can effectively solve the problems of easy bursting of composite current collectors during the winding process in pre-welding processes and the limitations on the industrial manufacturing of ultra-thin composite current collectors.

[0039] As an example, the thickness of the first metal layer is less than the thickness of the second metal layer. After the all-metal tab is formed, a third metal layer is formed on the side of the first metal layer facing away from the polymer substrate, and the sum of the thicknesses of the first metal layer and the third metal layer is the same as the thickness of the second metal layer.

[0040] It should be noted that the sum of the thicknesses of the first and third metal layers is the same as the thickness of the second metal layer because in the standard specifications of composite current collectors, the metal layers on both sides of the polymer substrate are usually of equal thickness. The advantage of this structural design is that the composite current collector has relatively excellent structural stability and electrochemical performance.

[0041] In this embodiment, the metal layer on the first side of the composite current collector is composed of a first metal layer and a third metal layer, and the metal layer on the second side is a second metal layer. This is equivalent to the metal layer on the first side being prepared using a stepwise method. The advantage of this process is that it can effectively solve the problem that after the formation of the first metal layer, the corresponding membrane material is prone to edge curling during subsequent transportation, transfer or temporary storage, which can lead to membrane material damage or reduced mechanical properties.

[0042] It should be noted that the inventors discovered that after the first metal layer is formed, the corresponding film material is prone to curling during subsequent transportation, transfer, or temporary storage. This is due to the material difference between the first metal layer and the polymer substrate, and the greater the thickness of the first metal layer, the more severe the curling problem becomes. Based on this, an innovative process for stepwise preparation of the metal layer is proposed.

[0043] It should be noted that the thickness of the first metal layer is not limited, theoretically as long as it does not exceed the thickness of the second metal layer.

[0044] As an example, the thickness of the first metal layer is 80 nm to 120 nm, for example, but not limited to any point value or a range between any two of the thicknesses of 80 nm, 90 nm, 100 nm, 110 nm and 120 nm.

[0045] In this embodiment, the thickness of the first metal layer is limited to the above-mentioned range so that the first metal layer has a more suitable thickness. On the one hand, it can effectively improve the problem of subsequent edge curling of the corresponding film material after the formation of the first metal layer. On the other hand, it can better serve as the substrate when the second metal layer is formed. At the same time, it also has the advantage of not being easily damaged or even broken during transportation or transfer.

[0046] In other possible implementations, a first metal layer of the same thickness as the second metal layer can be formed directly, i.e., preparation is not carried out in steps.

[0047] It should be noted that the thickness of the second metal layer is not limited and can be set according to actual needs. For example, it can be any one of 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm and 4 μm or any range between two.

[0048] As an example, the thickness of the second metal layer is 0.5 μm to 1.5 μm, for example, but not limited to any point value or a range between any two of the thicknesses of 0.5 μm, 0.6 μm, 0.8 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm and 1.5 μm.

[0049] In this embodiment, the thickness of the second metal layer is limited to the above-mentioned range, that is, the thickness of the metal layer on one side of the composite current collector is relatively thin and has a more suitable size range, so that the metal layer has better conductivity and mechanical properties. At the same time, it is highly consistent with the development direction of ultra-thin composite current collectors and has good development and application prospects.

[0050] As an example, the total thickness of the first metal layer, the second metal layer, and the third metal layer is no greater than the thickness of the polymer substrate.

[0051] In this embodiment, the total thickness of the metal layer is controlled to be no greater than the thickness of the polymer substrate. That is, the total thickness of the composite current collector in the tab area (without the polymer substrate, the total thickness is equal to the total thickness of the metal layer) is no greater than the thickness of the polymer substrate. This setting can better solve the problem of the composite current collector being prone to bursting during the winding process under the pre-welding process.

[0052] It should be noted that the method of forming the metal layer is not limited and can be adapted to actual needs. For example, it can be at least one of magnetron sputtering coating technology, magnetron sputtering combined with electroplating technology and one-step wet process technology.

[0053] As an example, the first metal layer, the second metal layer, and the third metal layer are all prepared using magnetron sputtering deposition technology.

[0054] In this embodiment, magnetron sputtering coating technology has the advantages of high deposition efficiency, low substrate temperature, wide applicability, stable process and environmental protection and economy. At the same time, the metal layer formed by this coating technology has the advantages of being dense and uniform, high in purity and having a relatively strong bond with the polymer substrate.

[0055] It should be noted that the material of the metal layer is not limited and can be adapted according to the type of composite current collector. For example, it can be copper (for the composite current collector used for the negative electrode) or aluminum (for the composite current collector used for the positive electrode).

[0056] To better understand the preparation process of the first metal layer, the specific preparation process of a copper-based first metal layer with a thickness of 80 nm to 120 nm is described here. The specific steps include: feeding the polymer substrate into the unwinding chamber of the magnetron sputtering equipment; then, conveying the polymer substrate through a guide roller to a vacuum-conditioned coating chamber to form the first metal layer; after the first metal layer is formed, conveying it through a guide roller to a take-up roller for winding; wherein the tension of the unwinding roller is 120 N ± 20 N, the tension of the guide roller is 100 N ± 20 N, and the tension of the take-up roller is 80 N ± 20 N; the vacuum degree in the magnetron sputtering coating chamber is 10 N. -4 Pa~10 -3 Pa, target-substrate distance of 10 cm to 15 cm, cold roller temperature of -25℃ to -10℃, conveying speed of 10 m / min to 20 m / min, six copper targets with a purity of 99.99% are set, total sputtering power of 40 kW to 60 kW, and ion source voltage of 400 V to 600 V.

[0057] As an example, the steps of forming the second metal layer and forming the third metal layer are performed sequentially in the same magnetron sputtering apparatus.

[0058] In this embodiment, the second metal layer and the third metal layer are prepared sequentially in the same magnetron sputtering equipment, that is, the interval between the preparation of the second metal layer and the preparation of the third metal layer is short. After the second metal layer is formed, the problem of film material curling caused by the thickness difference between the second metal layer and the first metal layer can be effectively improved.

[0059] To better understand the preparation process of the second and third metal layers, the specific preparation processes of the second metal layer (950 nm to 1050 nm thick and made of copper) and the third metal layer (850 nm to 950 nm thick and made of copper) are explained here. The specific steps include: feeding the polymer substrate with the first metal layer into the unwinding chamber of the magnetron coating equipment, then conveying the polymer substrate to the first coating chamber under vacuum conditions via a roller to form the second metal layer, and after the second metal layer is formed, conveying the polymer substrate with the second metal layer to the second coating chamber under vacuum conditions via a roller to form the third metal layer, and finally conveying it to the take-up roller for winding.

[0060] Specifically, in the step of forming the second metal layer: the unwinding roll tension is 80 N ± 20 N, the overwind roll tension is 60 N ± 20 N, the take-up roll tension is 80 N ± 20 N, and the vacuum degree in the magnetron sputtering coating chamber is 10 N. -4 Pa~10 -3 Pa, target-substrate distance of 10 cm to 15 cm, cold roller temperature of -35℃ to -25℃, conveying speed of 5 m / min to 10 m / min, six copper targets with a purity of 99.99% are set, total sputtering power of 80 kW to 120 kW, and ion source voltage of 600 V to 800 V.

[0061] Specifically, in the step of forming the third metal layer: the unwinding roll tension is 80 N ± 20 N, the overwind roll tension is 60 N ± 20 N, the take-up roll tension is 80 N ± 20 N, and the vacuum degree in the magnetron sputtering coating chamber is 10 N. -4 Pa~10 -3 Pa, target-substrate distance of 10 cm to 15 cm, cold roller temperature of -35℃ to -25℃, conveying speed of 5 m / min to 10 m / min, six copper targets with a purity of 99.99% are set, total sputtering power of 80 kW to 100 kW, and ion source voltage of 500 V to 700 V.

[0062] It should be noted that there are no restrictions on the methods used to remove the two ends of the polymer substrate, such as laser etching, plasma etching, mechanical stripping, and chemical etching.

[0063] As an example, laser etching technology is used to remove the regions at both ends of a polymer substrate.

[0064] In this embodiment, laser etching technology is used to remove the two ends of the polymer substrate, which has the advantages of high removal precision, no pollution, small heat-affected zone and high removal efficiency.

[0065] As an example, the type of laser is a carbon dioxide laser.

[0066] In this embodiment, the carbon dioxide laser is characterized by its ability to selectively etch and remove the polymer substrate on the surface of the metal layer, thereby enabling efficient and thorough removal of the regions at both ends of the polymer substrate while effectively protecting the metal layer.

[0067] It should be noted that the material of the polymer substrate is not limited and can be selected and set in accordance with the conventional methods in this field.

[0068] As an example, the polymer substrate is selected from at least one of BOPP, BOPET, BOPI and BOPE.

[0069] In this embodiment, the polymer substrate is selected from the above-mentioned materials, which have the advantages of good mechanical properties and heat resistance. At the same time, the polymer substrate is applicable to a wide variety of types, which can provide a large number of feasible implementation schemes.

[0070] As an example, the laser has a wavelength of 10.6 μm and an output power of 3 W to 5 W, for example, but not limited to any one of 3 W, 3.5 W, 4 W, 4.5 W and 5 W or any range between two.

[0071] In this embodiment, the wavelength and output power of the laser (i.e., the actual power applied to the polymer substrate) are respectively limited within the above-mentioned range, so that the selectivity of the laser on the polymer substrate is more precise, thereby enabling more efficient and thorough removal of the regions at both ends of the polymer substrate while effectively protecting the metal layer.

[0072] As an example, after removing the regions at both ends of the polymer substrate, both ends of the polymer substrate have a gradient section in the width direction, and the thickness of the gradient section gradually increases from the outside to the inside.

[0073] In this embodiment, the two ends of the polymer substrate are removed according to the above standard. Specifically, both ends of the polymer substrate along the width direction have a gradual transition section with the thickness gradually increasing from the outside to the inside. That is, both ends of the polymer substrate are inclined planes. In the subsequent step of forming the second metal layer, this type of end face has the advantage of facilitating the preparation of the second metal layer. At the same time, it also makes the formed second metal layer have the advantage of having a relatively uniform overall thickness.

[0074] To better understand the process of the gradient section, laser etching technology is used as an auxiliary explanation. The specific steps include: in the step of removing the regions at both ends of the width direction of the polymer substrate, the etching direction is from the outside to the inside, and the etching is first performed with a constant output power until the width of the tab region reaches the preset width. Then, the etching is performed with the power gradually decreasing until the power is 0.

[0075] As an example, in the width direction, the size of the exposed area of ​​the first metal layer at both ends is 20 mm to 40 mm, for example, but not limited to any one of 20 mm, 25 mm, 30 mm, 35 mm and 40 mm or any range between two.

[0076] In this embodiment, the width of the exposed area of ​​the first metal layer is limited to the above-mentioned range so that the subsequently formed all-metal tab area has a more suitable width, thereby facilitating direct welding with the external tab.

[0077] As an example, the thickness of the polymer substrate is 2 μm to 6 μm, for example, but not limited to any one of the thicknesses of 2 μm, 3 μm, 4 μm, 5 μm and 6 μm or any range between the two; and in the width direction, the size of a single gradient segment is 0.5 mm to 5 mm, for example, but not limited to any one of the sizees of 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm and 5 mm or any range between the two.

[0078] In this embodiment, when the thickness of the polymer substrate is within the above-mentioned range, the width of each gradient segment is also limited to the above-mentioned range so that the gradient segment has a more suitable tilt angle. In the subsequent step of forming the second metal layer, this type of end face has the advantage of facilitating the preparation of the second metal layer. At the same time, it also makes the formed second metal layer have the advantage of having a more uniform overall thickness.

[0079] It should be noted that, unless otherwise specified or limited, the processes or steps in the preparation of composite current collectors can be carried out in accordance with conventional processes in this field.

[0080] As an example, a process flow diagram of the preparation method of the all-metal tab composite current collector is exemplarily provided. Figure 1 .

[0081] Secondly, embodiments of this application provide a composite current collector, which is prepared using the preparation method provided in the first aspect embodiment.

[0082] In this application, the composite current collector is prepared by the method provided in the first aspect embodiment. Its tab region is all metal, so that it can be directly welded to the external tab. Compared with conventional composite current collectors (which require transfer welding), it has the advantages of high welding efficiency and more reliable welding. At the same time, since there is no polymer substrate at both ends of its width direction (i.e., at the tab), it can effectively solve the problem of easy bursting during the winding process. In addition, the metal layer of the composite current collector has the advantage of flexible thickness adjustment, which facilitates the realization of ultra-thinness.

[0083] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0084] Example 1 This application provides a method for preparing an all-metal composite current collector, comprising the following steps: S1 provides a BOPP polymer substrate with a thickness of 4.5 μm and a width of 1350 mm. Then, a first metal layer of copper with a thickness of 100 nm is formed on one side surface of the polymer substrate using magnetron sputtering coating technology. The specific steps include: feeding the polymer substrate into the unwinding chamber of the magnetron sputtering equipment; then conveying the polymer substrate through a guide roller to a vacuum-conditioned coating chamber to form the first metal layer; after the first metal layer is formed, conveying it through a guide roller to a take-up roller for winding; wherein the unwinding roller tension is 120 N, the guide roller tension is 100 N, the take-up roller tension is 80 N, and the vacuum degree in the magnetron sputtering coating chamber is 10 N. -4 The parameters are: Pa, target-substrate distance 10 cm, cold roller temperature -20℃, conveying speed 15 m / min, six copper targets with a purity of 99.99%, total sputtering power 50 kW, and ion source voltage 500 V. For a schematic diagram of the polymer substrate 100 with the first metal layer 200, please refer to [reference needed]. Figure 2 As can be seen, in the width direction a, the two ends of the first metal layer 200 and the polymer substrate 100 are aligned respectively.

[0085] S2 uses a 10.6 μm carbon dioxide laser and an output power of 4 W (calibrated and confirmed using a laser densitometer) to etch the regions at both ends of the polymer substrate along the width direction. Specifically, the etching direction is from the outside to the inside, and etching is first performed at a constant output power until the width of the first metal layer exposed on one side is 30 mm. Then, the output power is gradually reduced until it reaches 0, so that after the ends of the polymer substrate are removed, a gradient segment with a width of 1 mm is formed. For a schematic diagram of the structure of the polymer substrate 100 with the first metal layer 200 after the ends are removed, please refer to [link to schematic diagram]. Figure 3As can be seen, in the width direction a, the first metal layer 200 is exposed from both ends of the polymer substrate 100, and both ends of the polymer substrate 100 are inclined planes.

[0086] S3 feeds the polymer substrate with the first metal layer and both ends removed into the unwinding chamber of the magnetron coating equipment. Then, the polymer substrate is conveyed to the first coating chamber under vacuum conditions via the passing roller to form a second metal layer with a thickness of 1000 nm and made of copper. After the second metal layer is formed, the polymer substrate with the second metal layer is conveyed to the second coating chamber under vacuum conditions via the passing roller to form a third metal layer with a thickness of 900 nm and made of copper. Finally, it is conveyed to the take-up roller for winding.

[0087] Specifically, in the step of forming the second metal layer: the unwinding roll tension is 80 N, the overwind roll tension is 60 N, and the take-up roll tension is 80 N; in the magnetron sputtering coating chamber: the vacuum degree is 10. -4 The parameters are: Pa, target-substrate distance: 10 cm, cold roller temperature: -30℃, conveying speed: 8 m / min, target material: 6 copper targets with a purity of 99.99%, total sputtering power: 100 kW, and ion source voltage: 700 V.

[0088] Specifically, in the step of forming the third metal layer: the unwinding roll tension is 80 N, the overwind roll tension is 60 N, the take-up roll tension is 80 N, and the vacuum level in the magnetron sputtering coating chamber is 10 N. -4 The parameters are: Pa, target-substrate distance: 10 cm, cold roller temperature: -30℃, conveying speed: 8 m / min, target material: 6 copper targets with a purity of 99.99%, total sputtering power: 90 kW, and ion source voltage: 600 V.

[0089] Please refer to the structural schematic diagram of the composite current collector 10 with all-metal tabs. Figure 4 As can be seen, the metal layer on the first side of the polymer substrate 100 is composed of a first metal layer 200 and a third metal layer 400, and the metal layer on the second side is a second metal layer 300; and in the width direction a, the tab regions 11 at both ends of the composite current collector 10 are all metal layers without polymer substrate 100, and the total thickness of the metal layers corresponding to the tab regions 11 is less than the thickness of the polymer substrate 100.

[0090] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A method for preparing a composite current collector with all-metal tabs, characterized in that, Includes the following steps: A first metal layer is formed on one side surface of a polymer substrate, and the two ends of the polymer substrate and the first metal layer are flush in the width direction; Along the width direction, the regions at both ends of the polymer substrate are removed so that the first metal layer is exposed from both ends of the polymer substrate; A second metal layer is formed on the other side surface of the polymer substrate, on both ends of the polymer substrate along the width direction, and on the surface of the exposed area of ​​the first metal layer, so as to form all-metal tabs at both ends of the polymer substrate along the width direction.

2. The method for preparing the composite current collector with all-metal tabs according to claim 1, characterized in that, The thickness of the first metal layer is less than the thickness of the second metal layer. After the all-metal tab is formed, a third metal layer is formed on the side of the first metal layer facing away from the polymer substrate, and the sum of the thicknesses of the first metal layer and the third metal layer is the same as the thickness of the second metal layer.

3. The method for preparing the composite current collector with all-metal tabs according to claim 2, characterized in that, The thickness of the first metal layer is 80 nm to 120 nm, or / and the thickness of the second metal layer is 0.5 μm to 1.5 μm.

4. The method for preparing the composite current collector with all-metal tabs according to claim 2, characterized in that, The total thickness of the first metal layer, the second metal layer, and the third metal layer is not greater than the thickness of the polymer substrate.

5. The method for preparing the composite current collector with all-metal tabs according to claim 2, characterized in that, Both the second metal layer and the third metal layer are prepared using magnetron sputtering deposition technology; Optionally, the steps of forming the second metal layer and forming the third metal layer are performed sequentially in the same magnetron sputtering apparatus.

6. The method for preparing the composite current collector with all-metal tabs according to any one of claims 1 to 5, characterized in that, After removing the regions at both ends of the polymer substrate, both ends of the polymer substrate have a gradient section in the width direction, and the thickness of the gradient section gradually increases from the outside to the inside.

7. The method for preparing the composite current collector with all-metal tabs according to claim 6, characterized in that, In the width direction, the size of the exposed areas of the first metal layer at both ends is 20 mm to 40 mm; Or / and, the thickness of the polymer substrate is 2 μm to 6 μm, and the size of a single gradient segment is 0.5 mm to 5 mm in the width direction.

8. The method for preparing the composite current collector with all-metal tabs according to any one of claims 1 to 5, characterized in that, Laser etching technology is used to remove the regions at both ends of the polymer substrate; Optionally, the laser type is a carbon dioxide laser.

9. The method for preparing the composite current collector with all-metal tabs according to claim 8, characterized in that, The polymer substrate is selected from at least one of BOPP, BOPET, BOPI and BOPE, and / or the laser has a wavelength of 10.6 μm and an output power of 3 W to 5 W.

10. A composite current collector, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 9.

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