Integrated full-tab composite current collector and preparation method thereof
By using an integrated full-tab composite current collector design, the problem of weak tab welding in lithium battery manufacturing is solved, achieving efficient and stable tab connection and improving the safety and manufacturing efficiency of lithium batteries.
Patent Information
- Application Number
- CN202511540638.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-27
- Publication Date
- 2026-02-10
AI Technical Summary
In current lithium battery manufacturing, the welding of composite copper foil tabs suffers from problems such as weak welding, incomplete welding, perforation, increased internal resistance, and tab detachment, which are difficult to effectively solve using traditional welding processes.
An integrated multi-tab composite current collector is provided. By directly setting the first substrate and the tab on the second substrate and attaching them with a conductive adhesive layer, the process of separately welding the tab by the client is eliminated. The conductive adhesive layer is formed by mixing conductive filler and adhesive and then curing. Combined with processes such as slit extrusion coating and online plasma cleaning, the uniformity and firmness of the conductive adhesive layer are ensured.
This avoids problems such as weak welding, incomplete welding, perforation, and electrode detachment, saves on the production costs of subsequent processes at the customer end, improves production efficiency, and ensures the safety and stability of the battery.
Smart Images
Figure CN121506958A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium battery technology, specifically to an integrated all-tab composite current collector and its preparation method. Background Technology
[0002] With the rapid development of new energy vehicles and the energy storage industry, higher requirements have been placed on the safety, energy density, and manufacturing cost of lithium batteries. Composite copper foil, due to its advantages of light weight, low cost, and high safety, is regarded as an important development direction for key current collectors in next-generation lithium batteries.
[0003] However, when using composite copper foil in battery manufacturing, battery manufacturers need to perform an additional tab welding process. Because the composite current collector has a polymer insulating base film (such as PP, PE, PS, PTFE, PMMA, PET, PA, PI, etc.) in the middle and ultra-thin metal conductive layers on both sides, traditional ultrasonic welding or laser welding processes face huge challenges and are prone to problems such as weak welding, incomplete welding, perforation, increased internal resistance, and even tab detachment. Summary of the Invention
[0004] The purpose of this invention is to solve the problem that battery manufacturers need to perform additional electrode tab welding, and to provide an integrated full electrode tab composite copper foil, which eliminates the need for customers to weld the electrode tabs separately, thereby avoiding problems such as weak welding, incomplete welding, perforation, increased internal resistance, and even electrode tab detachment.
[0005] To achieve the above objectives, the present invention provides an integrated all-tab composite current collector, comprising a first substrate, a tab and a second substrate, wherein the first substrate and the tab are disposed on the second substrate at a distance, the tab extends out of the second substrate, and a conductive layer is disposed on at least one side of the second substrate and the tab.
[0006] Preferably, the first substrate and the second substrate are made of non-polar or low surface energy polymer materials.
[0007] Preferably, the first substrate and the tab are attached to the second substrate by a conductive adhesive layer, the entire surface of the first substrate is coated with the conductive adhesive layer, and the longitudinal edge of the tab is coated with the conductive adhesive layer.
[0008] Preferably, the conductive adhesive layer is formed by curing a conductive adhesive prepared by mixing conductive filler and binder with solvent, wherein the conductive filler includes carbon nanotubes.
[0009] Another aspect of the present invention provides a method for preparing the above-mentioned integrated all-electrode composite current collector, comprising the following steps:
[0010] S1. The conductive adhesive is coated on the entire surface of the first substrate and then dried and cured to form a conductive adhesive layer.
[0011] S2. After applying conductive adhesive to the longitudinal edge of the electrode tab, cure it to form a conductive adhesive layer and then roll it up.
[0012] S3. After cutting and removing the wide portion of the electrode tab, attach the first substrate and the electrode tab to the second substrate;
[0013] S4. Apply a base layer and a conductive layer to the attached material.
[0014] S5. After cutting to the required size, roll it up.
[0015] Preferably, the conductive adhesive is applied to the first substrate using a slit extrusion coating or a micro-gravure roller coating process.
[0016] Preferably, a stepped temperature rise curve of "low temperature-medium temperature-high temperature" is used to dry and cure the coated first substrate, wherein the low temperature is set to 60-80℃, the medium temperature is set to 100-120℃, and the high temperature is set to 130-150℃.
[0017] Preferably, before coating the tab with conductive adhesive, the surface of the tab is subjected to online plasma cleaning or micro-etching to remove the oxide layer, and the coating process is completed before it re-oxidizes naturally.
[0018] Preferably, when applying conductive adhesive to the tab, the middle part of the tab is precisely covered by a mask, exposing only the two sides of the tab as the coating area.
[0019] Preferably, during the application process, multiple rolls of the first substrate, multiple rolls of the tabs, and a second substrate with a width sufficient to attach these rolls are prepared. The coated rolls are then attached to the second substrate according to their corresponding dimensions. After the conductive layer is plated, the rolls are slit to obtain multiple rolls of products.
[0020] Compared with the prior art, the present invention directly sets the first substrate and the tab on the second substrate, eliminating the need for the client to separately weld the tab, thereby avoiding problems such as weak welding, false welding, perforation, increased internal resistance, and even tab detachment. At the same time, it saves the manufacturing cost of the client's subsequent processes and improves the manufacturing efficiency of the client's subsequent processes. Attached Figure Description
[0021] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts. Wherein:
[0022] Figure 1A schematic diagram of the structure of an integrated all-electrode composite current collector;
[0023] Figure 2 This is a cross-sectional schematic diagram of the first substrate and the tab attached to the second substrate.
[0024] The diagram is labeled as follows: 1. First substrate; 2. Tab; 3. Second substrate; 4. Conductive adhesive layer; 5. Underlayer; 6. Conductive layer. Detailed Implementation
[0025] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.
[0026] like Figure 1 As shown, the present invention provides a specific embodiment of an integrated full-tab composite current collector, including a first substrate 1, a tab 2, and a second substrate 3. The thickness of the first substrate 1 is the same as the thickness of the tab 2. The first substrate 1 and the tab 2 are attached to the second substrate 3 by a conductive adhesive layer 4. A gap is left between the first substrate 1 and the tab 2. The first substrate 1 is completely attached to the second substrate 3. One side of the tab 2 extends out of the second substrate 3. By attaching the first substrate 1 and the tab 2 to the second substrate 3, the process of separately welding the tab 2 by the client is eliminated, thereby avoiding problems such as weak welding, incomplete welding, perforation, increased internal resistance, and even detachment. At the same time, it saves the manufacturing cost of the client's subsequent processes and improves the manufacturing efficiency of the client's subsequent processes.
[0027] The first substrate 1 and the second substrate 3 are made of non-polar or low surface energy polymer materials, such as PP, PE, PS, PTFE, PMMA, PET, PA, and PI. At least one side of the second substrate 3 and the tab 2 is provided with an underlayer 5 and a conductive layer 6. Figure 1 As shown in the figure, this application demonstrates a structure in which conductive layers 6 are provided on both sides of the attached product. It should be noted that conductive layers 6 can also be provided on only one side of the attached product, and there is no limitation here.
[0028] The thickness of the conductive adhesive layer 4 is set to be not less than 0.5 μm, preferably 0.5 μm. The width of the conductive adhesive layer 4 on the longitudinal side of the tab 2 is set to be not less than 5 mm, preferably 5 mm. The viscosity of the conductive adhesive layer 4 at 25℃ is 2000-5000 mPa·s. The adhesion performance of the conductive adhesive layer 4 is greater than 10 MPa. The temperature resistance range of the conductive adhesive layer 4 is -40℃ to 120℃ to ensure the stability of the adhesion. The conductivity of the conductive adhesive layer 4 is less than 10-4 Ω / cm to ensure the conductivity. The sum of the thicknesses of the first substrate 1 and the second substrate 3 is set to 2.5-8 μm to ensure lightweight.
[0029] The present invention also provides a specific embodiment of the preparation method for the above-mentioned integrated all-electrode composite current collector, including preparing two rolls of first substrate 1 with a width of 250 mm, one roll of first substrate 1 with a width of 500 mm, two rolls of electrode 2 with a width of 50 mm, and one roll of second substrate 3 with a width of 1350 mm.
[0030] Example 1
[0031] Example 1 is used to prepare an integrated all-tab composite aluminum foil. Before preparation, a conductive adhesive specifically for aluminum deposition is prepared. The conductive filler includes nano-aluminum powder and carbon nanotubes. The binder is a resin system with good affinity to aluminum surface oxides, such as a specially modified acrylic resin or polyurethane. A solvent is added to adjust the viscosity to a suitable coating viscosity, preferably 2000-5000 mPa·s at 25°C.
[0032] The conductive adhesive is applied to the first substrate 1 using a slot extrusion coating method to ensure 100% defect-free and uniform coating on the first substrate 1. The flow rate of the adhesive and the speed of the base film are strictly controlled by a high-precision metering pump and an automatic die lip control system to ensure that the wet film thickness is stable at 1μm. An online thickness gauge is used for real-time monitoring and feedback adjustment. Slot extrusion coating is a high-precision coating process that uses a die to squeeze the slurry through a slot and transfer it to the surface of the substrate to form a uniform coating. As it is an existing technology, it will not be described in detail here.
[0033] The coated first substrate 1 is guided through a multi-temperature zone oven, using a stepped heating curve of "low temperature-medium temperature-high temperature", such as 60℃→100℃→130℃, to ensure that the solvent evaporates slowly and fully, avoiding surface skinning and the formation of pores. The cured dry film serves as the conductive adhesive layer 4, with a target thickness of 0.5μm. After cooling, the uniformity and defects of the coated surface are checked by an online visual inspection system. Finally, it is wound up to produce a conductive base film that can be used for subsequent bonding.
[0034] The surface of the aluminum foil tab 2 is subjected to online plasma cleaning or micro-etching to instantly remove its natural and dense alumina insulating layer. Subsequent coating is then performed before it re-oxidizes naturally. Coating is carried out using a slit coating head with a precision mask or multiple independently controlled dispensing valves. The mask precisely blocks the 40mm area in the middle of the aluminum foil, exposing only the 5mm wide coating areas on both sides. The coating head is controlled to precisely apply conductive adhesive to the 5mm wide areas on both sides, controlling the wet film thickness to 1μm. Curing is performed at 80-110℃ to prevent excessive oxidation and deformation of the aluminum foil tab 2. After curing, two strong conductive adhesive layers 4 with a dry film thickness of 0.5μm and a width of 5mm are formed. The layers are then wound up as quickly as possible under an inert gas protection environment to minimize oxidation. It should be noted that the dry film thickness will significantly decrease after solvent evaporation and curing of the 1μm wet film.
[0035] On the second substrate 3, the two rolls of pure aluminum foil tabs 2 to be attached later are cut and removed in 40mm widths. Then, as follows... Figure 2 As shown, the coated roll material is attached to the second substrate 3 according to the corresponding size. The attached material is then fed to a magnetron sputtering coating machine to deposit aluminum oxide on sides A and B as the underlayer 5, which can increase the adhesion of the subsequent evaporated aluminum layer. Aluminum oxide is deposited on both sides A and B with a thickness of 20-40nm. Subsequently, the roll film is fed to an evaporation aluminum coating machine to deposit aluminum layers on sides A and B as the conductive layer 6. The total thickness of the underlayer 5 and the conductive layer 6 is set to 300-1000nm, preferably 1000nm.
[0036] Finally, the material is fed into the precision slitting machine. Figure 2 The process involves slitting and winding. Five circular slitting blades are used, each spaced 280mm apart, with the sides being unusable portions. This yields four rolls of 260mm wide, integrated all-metal tab composite aluminum foil, with a uniform thickness for easy winding.
[0037] Example 2
[0038] Example 2 is used to prepare an integrated all-tab composite copper foil. First, the conductive adhesive is prepared: conductive filler including carbon nanotubes is mixed with polymer binder (such as epoxy resin, polyurethane resin) in a certain proportion, and an appropriate amount of solvent (such as methyl ethyl ketone, N-methylpyrrolidone, etc.) is added to adjust the viscosity to 2000-5000 mPa·s at 25°C.
[0039] The first substrate 1 is coated using a slit extrusion coating process. This method can achieve high-precision, large-area uniform coating. The conductive adhesive is delivered to the coating head by a high-precision metering pump. The pressure of the coating head, the conveyor speed of the base film, and the supply speed of the adhesive are controlled to ensure that a uniform and continuous wet film is formed on the entire surface of the base film (100% coating area). The wet film thickness is monitored in real time using an online thickness gauge (such as a beta-ray or infrared thickness gauge), and the coating parameters are dynamically adjusted through a closed-loop control system to control the wet film thickness at 1μm. Slit extrusion coating is a high-precision coating process that uses a die slit to extrude the slurry and transfer it to the surface of the substrate to form a uniform coating. As it is an existing technology, it will not be described in detail here.
[0040] The coated first substrate 1 is guided through a multi-temperature drying oven (such as a 5-10 meter long tunnel oven) and dried and cured under a specific temperature profile (e.g., stepwise temperature increase from 80℃ to 120℃ to 150℃) to allow the solvent to fully evaporate, the conductive adhesive layer 4 to be completely cured and form a strong bond with the first substrate 1. The cured dry film serves as the conductive adhesive layer 4, with a target thickness of 0.5 μm. It should be noted that the thickness of the dry film will be significantly reduced after solvent evaporation and curing of a 1 μm wet film. The cured film is cooled by a cooling roller, and an online defect detection system is used to check the uniformity of the coating surface and for defects such as pinholes and scratches.
[0041] The surface of the copper foil tab 2 is degreased and micro-etched to remove oil and oxide layers, ensuring good adhesion of the conductive adhesive layer 4. A precision mask is installed in front of the coating head using a selective coating method. The opening of the mask is precisely designed to expose only the areas on both sides of the copper foil tab 2 that need to be coated (5mm wide on each side) as the coating area, while covering the 40mm wide area in the middle. A precision slit coating head or adhesive spray valve is used for coating. The position of the coating head relative to the copper foil tab 2 is controlled to ensure that the adhesive is accurately coated on the 5mm wide areas exposed on both sides. The coating parameters are controlled so that the wet film thickness of each tape is 1μm and the width is 5mm. The conductive adhesive is cured by step temperature increase in a drying oven. After curing, two strong conductive adhesive layers 4 with a dry film thickness of 0.5μm and a width of 5mm are formed on both sides of the copper foil tab 2. After cooling, the tape is wound up.
[0042] On the second substrate 3, the two rolls of pure copper foil tabs 2 to be attached later are cut and removed in 40mm widths. Then, as follows... Figure 2 The coated roll material is attached to the second substrate 3 according to the corresponding size. The attached material is then fed to a winding magnetron sputtering machine to plate copper on sides A and B as the underlayer 5. Copper is plated on both sides A and B with a thickness of 70-90nm. The roll film is then fed to the water plating line, where sides A and B are water-plated to thicken them as the conductive layer 6. The total thickness of the underlayer 5 and the conductive layer 6 is set to 300-1000nm, preferably 1000nm.
[0043] Finally, the material is fed into the precision slitting machine. Figure 2 The process involves slitting and winding. Five circular slitting blades are used, each spaced 280mm apart, with the sides being unusable portions. This yields four rolls of 260mm wide, integral all-metal tab composite copper foil, with a uniform thickness for easy winding.
[0044] The integrated all-tab composite current collector prepared by this invention can eliminate the need for a separate welding process at the client end, thereby saving the manufacturing cost of the client end process and improving the manufacturing efficiency of the client end process. Moreover, it solves the problem of thickness difference in all-metal tab composite current collectors.
[0045] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.
Claims
1. An integrated all-electrode composite current collector, characterized in that: It includes a first substrate (1), a tab (2) and a second substrate (3), wherein the first substrate (1) and the tab (2) are disposed on the second substrate (3) at a distance, the tab (2) extends out of the second substrate (3), and a conductive layer (6) is disposed on at least one side of the second substrate (3) and the tab (2).
2. The integrated all-electrode composite current collector according to claim 1, characterized in that: The first substrate (1) and the second substrate (3) are made of non-polar or low surface energy polymer materials.
3. The integrated all-electrode composite current collector according to claim 1, characterized in that: The first substrate (1) and the tab (2) are attached to the second substrate (3) through a conductive adhesive layer (4). The entire surface of the first substrate (1) is coated with the conductive adhesive layer (4), and the longitudinal edge of the tab (2) is coated with the conductive adhesive layer (4).
4. The integrated all-electrode composite current collector according to claim 3, characterized in that: The conductive adhesive layer (4) is formed by curing a conductive adhesive prepared by mixing a conductive filler and a binder with a solvent. The conductive filler includes carbon nanotubes.
5. A method for preparing the integrated all-electrode composite current collector according to any one of claims 1-4, characterized in that: Includes the following steps, S1. The conductive adhesive is coated on the entire surface of the first substrate (1) and then dried and cured to form a conductive adhesive layer (4). S2. After applying conductive adhesive to the longitudinal edge of the tab (2), the adhesive is cured to form a conductive adhesive layer (4) and then wound up. S3. After cutting and removing the wide portion of the tab (2), attach the first substrate (1) and the tab (2) to the second substrate (3); S4. Apply a base layer (5) and a conductive layer (6) to the attached material. S5. After cutting to the required size, roll it up.
6. The method according to claim 5, characterized in that: The first substrate (1) is coated with conductive adhesive using a slit extrusion coating or a micro-gravure roller coating process.
7. The method according to claim 5, characterized in that: The first substrate (1) after coating was dried and cured using a stepped heating curve of "low temperature-medium temperature-high temperature", where the low temperature was set to 60-80℃, the medium temperature was set to 100-120℃, and the high temperature was set to 130-150℃.
8. The method according to claim 5, characterized in that: Before coating the tab (2) with conductive adhesive, the surface of the tab (2) is subjected to online plasma cleaning or micro-etching to remove the oxide layer, and the coating is completed before it is naturally oxidized again.
9. The method according to claim 5, characterized in that: When applying conductive adhesive to the tab (2), the middle part of the tab (2) is precisely covered by a mask, exposing only the two sides of the tab (2) as the coating area.
10. The method according to claim 5, characterized in that: During the application process, multiple rolls of the first substrate (1), multiple rolls of the tabs (2), and a second substrate (3) with a width sufficient to apply these rolls are prepared. The coated rolls are then applied to the second substrate (3) according to their corresponding dimensions. After the conductive layer (6) is plated, it is slit to obtain multiple rolls of products.