Composite copper foil current collector, manufacturing method thereof and lithium ion battery

Abstract

The invention relates to the technical field of batteries, in particular to a composite copper foil current collector and a manufacturing method thereof and a lithium ion battery, the composite copper foil current collector comprises a base material, a pure copper foil tab, a magnetic control copper layer and a water plating copper layer, the pure copper foil tab is welded on one side of the base material, and the magnetic control copper layer is welded on the other side of the base material. The magnetic control copper layers are arranged on the upper sides and the lower sides of the base material and the pure copper foil tabs, and the water plating copper layers are arranged on one sides of the magnetic control copper layers. Copper plating is carried out after the base material and the pure copper foil tabs are welded, the independent tab welding link is reduced, compared with traditional composite copper foil, the working procedure that the tabs are independently welded by a client side is omitted, the subsequent manufacturing cost of the client side is saved, and the subsequent manufacturing efficiency of the client side is improved; the weight is relatively light, the energy density is relatively high, and the safety is relatively high.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a composite copper foil current collector and a manufacturing method thereof, and a lithium ion battery. Background Art

[0002] As energy demand continues to increase, lithium batteries, as important energy storage devices, are widely used in portable electronic devices, power tools, electric vehicles, etc. In recent years, as the application areas of lithium batteries have gradually expanded, the requirements for battery weight, energy density and safety have continued to increase, and the design that simply relies on traditional copper foil current collectors can no longer meet the needs.

[0003] In order to overcome the shortcomings of traditional copper foil materials, composite copper foil has emerged as a new generation of negative electrode current collector. It can reduce the weight of the negative electrode current collector while maintaining good conductivity, improve the energy density of the battery, and thus improve the overall performance and safety of the battery. However, there are still some challenges in the current production process of composite copper foil, especially in the subsequent addition of the pole ear welding process. Composite copper foil needs to go through an additional pole ear welding process. The pole ear is used to prevent short circuit failures between the metal strip and the aluminum-plastic film during battery packaging. During packaging, it is heated (about 140°C) and hot-melt sealed with the aluminum-plastic film to prevent leakage, which not only increases the process time, but also brings additional process costs. The pole ear is an important component of the negative electrode current collector of the battery. It is usually used to prevent short circuit problems between the metal strip and the aluminum-plastic film, and is bonded to the aluminum-plastic film through hot-melt sealing technology during battery packaging to ensure the safety and stability of the battery.

[0004] Therefore, adding the tab welding process to the production process of composite copper foil undoubtedly brings additional processes and cost burdens to production. This problem has become a bottleneck in the current technological development. How to reduce the process time and cost of tab welding while ensuring battery performance is a key technical problem that needs to be solved urgently. Summary of the invention

[0005] The purpose of the present invention is to solve the problem in the prior art that adding a pole ear welding step in the manufacturing process of composite copper foil undoubtedly brings additional steps and cost burden to production, and provide a composite copper foil current collector and a manufacturing method thereof, and a lithium ion battery. By first welding a substrate and a pure copper foil pole ear and then copper plating, the pole ear welding is advanced to the substrate processing stage, and the traditional post-process is replaced by roll-to-roll continuous welding, thereby reducing the separate pole ear welding link.

[0006] To achieve the above object, a composite copper foil current collector proposed by the present invention includes a substrate, a pure copper foil tab, a magnetron sputtered copper layer, and an electroplated copper layer. The pure copper foil tab is welded to one side of the substrate. The magnetron sputtered copper layer is disposed on both the upper and lower sides of the substrate and the pure copper foil tab. The electroplated copper layer is disposed on one side of the magnetron sputtered copper layer.

[0007] A method for manufacturing a composite copper foil current collector includes the following steps: S1, welding a pure copper foil tab onto a substrate roll; S2, performing magnetron sputtering copper plating on both sides of the welded coil to form a magnetron sputtered copper layer; S3, performing electroplating copper on the magnetron sputtered copper layers on both sides of the welded coil to form an electroplated copper layer; S4, slitting the formed coil to obtain a composite copper foil current collector coil.

[0008] As a further description of the above technical solution: In step S1, two rolls of the pure copper foil tabs are welded to one roll of the substrate by a roll-to-roll rolling welding using a rewinder.

[0009] As a further description of the above technical solution: In step S1, before winding up the welded coil, the substrate within the welding area is wound around a waste shaft and torn off.

[0010] As a further description of the above technical solution: In step S2, the coil film welded with the pure copper foil tab is loaded onto a winding magnetron sputtering coating machine for double-sided copper plating as a primer, with each side plated with copper having a thickness of 80 ± 10 nm.

[0011] As a further description of the above technical solution: In step S3, the coil film coated with the magnetron sputtered copper layer is loaded onto an electroplating line, and both sides are electroplated to quickly increase the thickness of the copper layer to 1000 ± 50 nm.

[0012] As a further description of the above technical solution: In step S4, the coil film coated with the electroplated copper layer is loaded onto a precision slitter for slitting and winding.

[0013] As a further description of the above technical solution: In step S4, five slitting circular blades are provided on the precision slitter. Slitting the coil film coated with the electroplated copper layer can obtain four rolls of composite copper foil current collector coils.

[0014] As a further description of the above technical solution: The width of each roll of the substrate is 1350 mm and the thickness is 4.5 μm. The width of each roll of the pure copper foil tab is 44 mm and the thickness is 4.5 μm.

[0015] A lithium-ion battery includes the composite copper foil current collector as described in claim 1, or the method for manufacturing a composite copper foil current collector as described in any one of claims 2 to 9.

[0016] The above technical solution has the following advantages or beneficial effects:

[0017] 1. After welding the base material with the pure copper foil tab and then plating copper, the present invention reduces the separate tab welding link. Compared with traditional composite copper foils, it eliminates the process of separately welding tabs at the client side, saving the subsequent manufacturing cost at the client side and improving the subsequent manufacturing efficiency at the client side. Compared with pure copper foils, it has a lighter weight, a higher energy density, and higher safety.

[0018] 2. By welding the base material with the pure copper foil tab first and then plating copper, the present invention advances the tab welding to the base material treatment stage. It replaces the traditional post - process with roll - to - roll continuous welding, reduces the separate tab welding link, shortens the process flow, and adopts a synergistic thickening process of magnetron sputtering and electroplating to form a magnetron copper layer and an electroplated copper layer, enhancing the bonding strength of the copper layer, saving the subsequent manufacturing cost at the client side, improving the subsequent manufacturing efficiency at the client side, increasing the battery energy density, and enhancing the battery safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of a composite copper foil current collector in an embodiment of the present invention;

[0020] Figure 2 It is a schematic manufacturing process diagram of a composite copper foil current collector in an embodiment of the present invention;

[0021] Figure 3 For Figure 1 It is a schematic structural diagram of the base material roll film welded with pure copper foil in

[0022] Figure 4 For Figure 1 It is a schematic structural diagram of the base material roll film magnetron - plated with copper in

[0023] Figure 5 For Figure 1 It is a schematic structural diagram of the base material roll film electro - plated with copper in

[0024] Figure 6 For Figure 1 It is a schematic diagram of the base material roll film slitting in Figure 1 ;

[0025] Figure 7 For Figure 1 It is a schematic structural diagram of the base material roll in

[0026] Figure 8 For Figure 1 It is a schematic diagram of the base material roll film slitting in Figure 2 ;

[0027] Figure 9 For Figure 1 It is a schematic diagram of the base material roll film slitting in Figure 3 。

[0028] Legend Explanation:

[0029] 1. Substrate; 2. Pure copper foil tab; 3. Magnetron copper layer; 4. Electroplated copper layer. Detailed Implementation Manner

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "vertical", "upper", "lower", "horizontal", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention 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 invention.

[0032] In the description of the present invention, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] Please refer to Figure 1 , the present invention provides a technical solution: A composite copper foil current collector of the present invention includes a substrate 1, a pure copper foil tab 2, a magnetron copper layer 3, and an electroplated copper layer 4. The pure copper foil tab 2 is welded to one side of the substrate 1, the magnetron copper layer 3 is provided on the upper and lower sides of the substrate 1 and the pure copper foil tab 2, and the electroplated copper layer 4 is provided on one side of the magnetron copper layer 3.

[0034] In the technical solution of the present invention, by plating copper after welding the substrate 1 and the pure copper foil tab 2, the separate tab welding link is reduced. Compared with the traditional composite copper foil, the process of separately welding the tab at the client side is omitted, saving the subsequent production cost of the client side and improving the subsequent production efficiency of the client side. Compared with the pure copper foil, it has a lighter weight, a higher energy density, and a higher safety. At a thickness of 6.5 μm, the weight is reduced by about 62%, the battery energy density is increased, and the safety is further enhanced.

[0035] Please refer to Figure 2-9, A method for manufacturing a composite copper foil current collector of the present invention includes the following steps:

[0036] S1. Weld a pure copper foil tab 2 on a substrate 1 roll; S2. Perform magnetron copper plating on both sides of the welded coil to form a magnetron copper layer 3; S3. Perform electroplated copper plating on the magnetron copper layer 3 on both sides of the welded coil to form an electroplated copper layer 4; S4. Cut the formed coil to obtain a composite copper foil current collector coil.

[0037] In the technical solution of the present invention, by first welding the substrate 1 and the pure copper foil tab 2 and then performing copper plating, the tab welding is pre-positioned to the substrate treatment stage. The roll-to-roll continuous welding is used to replace the traditional post-process, reducing the separate tab welding link and shortening the process flow. The magnetron sputtering and electroplated copper plating synergistic thickening process is adopted to form the magnetron copper layer 3 and the electroplated copper layer 4, improving the bonding strength of the copper layer and avoiding the interface separation problem caused by secondary processing. Compared with the traditional composite copper foil, the process of separately welding the tab at the client side is omitted, saving the subsequent manufacturing cost of the client and improving the subsequent manufacturing efficiency of the client. Compared with the pure copper foil, it has a lighter weight, a higher energy density and a higher safety. At a thickness of 6.5 μm, the weight is reduced by about 62%, the battery energy density is increased, and the safety is further enhanced.

[0038] Among them, each roll of substrate 1 has a width of 1350 mm and a thickness of 4.5 μm, and each roll of pure copper foil tab 2 has a width of 44 mm and a thickness of 4.5 μm. The two rolls of pure copper foil tabs 2 are welded to one roll of substrate 1 by a roll-to-roll rolling welding through a rewinder. Prepare one roll of substrate 1 with a width of 1350 mm * a thickness of 4.5 μm made of materials such as PET / PP / PI / PPS and two rolls of pure copper foil tabs 2 with a width of 44 mm * a thickness of 4.5 μm. Perform roll-to-roll rolling welding on the roll-to-roll rewinder according to the dimensions shown in the figure. The running speed is 100 ± 30 m / min, the unwind tension is 100 N ± 10 N, and the take-up tension device can be adjusted adaptively. The welding width is 2 ± 1 mm, the welding down pressure is 0.4 ± 0.1 Mpa, and the amplitude is 40 ± 10%.

[0039] The all-metal tab structure eliminates the risk of polymer exposure and reduces the short-circuit probability; the copper-polymer-copper sandwich structure effectively inhibits dendrite penetration and passes the 200% overcharge test; the overall thickness of 6.5 μm is 15% thinner than the traditional copper foil, increasing the battery volume energy density by 8 - 10%.

[0040] Specifically, before winding the welded coil, the substrate in the welding area is wound around the waste shaft and torn off; before winding, the substrate in the welding area is wound around the waste shaft and torn off, and the take-up shaft tension is 120 N ± 10 N.

[0041] Such as Figure 2 and Figure 4As shown, in step S2, the film roll with the pure copper foil tab 2 welded is loaded onto a winding magnetron sputtering coater for copper plating on both sides as a primer, with 80 ± 10 nm thick copper plated on each side; the film roll with the pure copper foil tab 2 welded is loaded onto a winding magnetron sputtering coater for copper plating on the A / B sides as a primer, with 80 ± 10 nm thick copper plated on the A / B sides respectively. The running speed is 20 m / min, there are 14 copper targets on each side, the total power is controlled at 120 ± 5 kw, and the ion source cleaning voltage is 700 V.

[0042] Specifically, during the copper plating process on both sides (A / B sides), the copper plating thickness on each side is 80 ± 10 nm, which can ensure that the copper layer evenly covers the surface of the pure copper foil tab 2. The uniform copper layer can not only improve the conductivity of the material, but also enhance its corrosion resistance and structural stability, which is helpful for subsequent welding and electronic component applications. With a running speed of 20 m / min, the relatively high production speed can significantly improve production efficiency. For large-scale production, increasing the speed helps to increase output and reduce production costs while maintaining the stability of the copper layer quality. 14 copper targets are used for coating on each side. This multi-target configuration can provide relatively uniform and efficient copper deposition. In this way, it can ensure that under a relatively high production speed, the quality and uniformity of the copper layer are well controlled. The ion source cleaning voltage is 700 V, which helps to remove pollutants or impurities generated during the coating process, improve the film quality and stability during the coating process. The clean ion source can also improve the uniformity of the coating surface, thereby enhancing the adhesion and electrical properties of the copper layer.

[0043] As Figure 2 and Figure 5 shown, in step S3, the film roll with the magnetron copper layer 3 coated is loaded onto the aqueous plating line, and aqueous plating is carried out on both sides to quickly increase the thickness of the copper layer to 1000 ± 50 nm; the film roll with the magnetron copper layer 3 coated as a primer is loaded onto the aqueous plating line, and aqueous plating is carried out on the A / B sides of the film roll to quickly increase the thickness of the copper layer to 1000 ± 50 nm. The unwind tension is 90 ± 10 N, the rewind tension is 80 ± 10 N, the speed is 12 ± 2 m / min, and the total current of the rectifier is 5500 ± 500 A. At this time, the film roll thickness is 4.5 μm substrate + 2 μm copper layer = 6.5 μm.

[0044] With a 4.5 μm polymer substrate + 2 μm composite copper layer structure, the weight is reduced by more than 60% compared with the traditional 6 μm copper foil, and the mass per unit area ≤ 24 g / m 2 ; 1 μm of copper is plated on both sides (80 nm by magnetron sputtering + 920 nm by aqueous electroplating), the surface resistance ≤ 20 mΩ / □, and the electrical conductivity is comparable to that of traditional copper foil; the tab welding area uses a 4.5 μm pure copper foil to match the substrate thickness, and the reliability of heat fusion sealing is increased by 40%.

[0045] Specifically, the roll-to-roll process speed reaches 12 m / min (in the electroplating section), and the annual production capacity per line can reach 3 million square meters; the equipment is compatible with various substrates such as PET / PP / PI / PPS, and the switching time is less than 4 hours; the waste reel system can automatically remove 100% of the welding area, and the yield rate is greater than 95%.

[0046] As Figure 2 , Figure 6 , Figure 8 and Figure 9 shown, in step S4, the rolled film coated with the electroplated copper layer 4 is loaded onto the precision slitter for slitting and winding; finally, it is loaded onto the precision slitter for slitting and winding as shown in the figure. The cutting tool rotation speed is 50 m / min, the equipment running speed is 80 m / min, the unwind tension is 100 N ± 20 N, and the winding tension can be adjusted adaptively by the equipment.

[0047] Among them, five slitting circular blades are arranged on the precision slitter. Slitting the rolled film coated with the electroplated copper layer 4 can obtain four rolls of composite copper foil current collector coils; five slitting circular blades are arranged on the precision slitter, with each blade spaced 280 mm apart, and four rolls of composite copper foil current collector coils with a width of 20 mm * 260 mm can be obtained; a five-knife slitting system with a 280 mm interval is developed to achieve single-pass processing of four rolls of 260 mm wide products, and the material utilization rate reaches 98.5%.

[0048] By setting five slitting circular blades with a spacing of 280 mm between each blade, efficient slitting operations can be achieved. The slitting speed reaches the equipment running speed of 80 m / min, and the cutting tool rotation speed is 50 m / min, ensuring the cutting accuracy and efficiency under high-speed operation. This configuration can effectively improve production efficiency and reduce the production cycle. During each slitting process, four independent rolls of composite copper foil current collector coils can be obtained by cutting with five blades. This not only increases the production output but also effectively improves production efficiency. At the same time, the size and quality of each roll can be kept consistent. The setting of the precision slitter enables it to process materials of different specifications and thicknesses, with strong adaptability. In different production batches, the blade spacing and slitting speed can be quickly adjusted according to requirements to ensure that the cutting needs of various different specifications of composite copper foil current collectors are met. By optimizing the slitter configuration, precise tension control, and efficient slitting methods, production efficiency can be significantly improved, the consistency of product quality can be ensured, and human intervention can be reduced, further improving the automation level and stability of the production line.

[0049] Specifically, through process reconstruction and material innovation, the industrialization bottleneck of composite current collectors has been successfully broken through, reducing the comprehensive cost of tab welding by 45%, and providing a new generation of current collector solutions for power batteries with high safety, high energy density, and low cost.

[0050] Working principle: By welding the substrate 1 and the pure copper foil tab 2 first and then copper plating, the tab welding is advanced to the substrate processing stage, and the traditional post-process is replaced by roll-to-roll continuous welding to reduce the individual tab welding link and shorten the process flow. The magnetron sputtering and water electroplating synergistic thickening process is used to form a magnetron copper layer 3 and a water-plated copper layer 4, which improves the bonding strength of the copper layer and avoids the interface separation problem caused by secondary processing. Compared with traditional composite copper foil, the process of welding the tab separately is eliminated, which saves the subsequent production cost of the client and improves the subsequent production efficiency of the client. Compared with pure copper foil, it has lighter weight, higher energy density and higher safety. At a thickness of 6.5μm, the weight is reduced by about 62%, the battery energy density is improved, and the safety is further enhanced. Through process reconstruction and material innovation, a new generation of current collector solutions with high safety, high energy density and low cost are provided for power batteries.

[0051] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0052] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A composite copper foil current collector, characterized in that, It includes a substrate, a pure copper foil tab, a magnetron copper layer, and a water electroplated copper layer. The pure copper foil tab is welded to one side of the substrate. The magnetron copper layer is disposed on the upper and lower sides of the substrate and the pure copper foil tab. The water electroplated copper layer is disposed on one side of the magnetron copper layer.

2. A method for manufacturing a composite copper foil current collector, characterized in that, It includes the following steps: S1. Weld the pure copper foil tab on the substrate roll. S2. Perform magnetron copper plating on both sides of the welded coil to form a magnetron copper layer. S3. Perform water electroplating on the magnetron copper layers on both sides of the welded coil to form a water electroplated copper layer. S4. Slit the formed coil to obtain a composite copper foil current collector coil.

3. The method for manufacturing a composite copper foil current collector according to claim 2, characterized in that: In step S1, two rolls of the pure copper foil tabs are roll-to-roll welded on one roll of the substrate by a rewinder.

4. The method for manufacturing a composite copper foil current collector according to claim 3, wherein: In step S1, before winding up the welded coil, the substrate within the welding area is wound around a waste shaft and torn off.

5. The manufacturing method of the composite copper foil current collector according to claim 2, characterized in that: In step S2, the coil film welded with the pure copper foil tab is loaded onto a winding magnetron coating machine for double-sided copper plating as a primer, with each side plated with copper having a thickness of 80 ± 10 nm.

6. The manufacturing method of the composite copper foil current collector according to claim 2, characterized in that: In step S3, the coil film plated with the magnetron copper layer is loaded onto a water plating line, and water plating is performed on both sides to quickly increase the thickness of the copper layer to 1000 ± 50 nm.

7. The method for manufacturing a composite copper foil current collector according to claim 2, wherein: In step S4, the coil film plated with the water electroplated copper layer is loaded onto a precision slitter for slitting and winding up.

8. The method for manufacturing a composite copper foil current collector according to claim 7, wherein: In step S4, five slitting circular blades are provided on the precision slitter. Slitting the coil film plated with the water electroplated copper layer can obtain four rolls of composite copper foil current collector coils.

9. The method for manufacturing a composite copper foil current collector according to claim 3, wherein: The width of each roll of the substrate is 1350 mm and the thickness is 4.5 μm. The width of each roll of the pure copper foil tab is 44 mm and the thickness is 4.5 μm.

10. A lithium-ion battery, characterized in that, The lithium-ion battery contains the composite copper foil current collector as described in claim 1, or the method for manufacturing the composite copper foil current collector as described in any one of claims 2 to 9.

Images