Riveted multi-layer current collector, preparation method thereof, electrode plate and battery
Through the preparation method of riveted multi-layer current collector, the problem of metal layer falling off and delamination in lithium-ion batteries is solved, and the battery is higher cycling performance and lower square resistance are achieved.
Patent Information
- Application Number
- CN202411876037.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-19
- Publication Date
- 2025-03-21
AI Technical Summary
The current collector of existing lithium-ion batteries is prone to fall off and delamination during use, resulting in the failure of battery capacity.
The preparation method of riveted multi-layer current collector is adopted, and the first metal foil, polymer substrate and second metal foil are connected into a three-layer structure through welding tooth roller welding, and the layers are connected tighter through pressing to form a stable riveted multi-layer current collector.
By using the riveted multi-layer current collector, the metal layer can be avoided to fall off, the circulation performance of the battery can be improved, the square resistance of the current collector can be reduced, and the peeling force of the battery active substance can be increased.
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Figure CN119674095A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of batteries, and in particular to a riveted multilayer current collector and a preparation method thereof, an electrode sheet and a battery. Background Art
[0002] Lithium-ion batteries have the advantages of high energy density, good cycle stability, and relatively environmentally friendly. They can be used in a variety of different fields, from 3C products to electric vehicles and ships, and occupy a large proportion of the global new energy market. The cost of battery use is an important direction that needs to be continued.
[0003] At present, in order to reduce the cost of battery use, optimization design is mainly carried out from the perspective of battery materials, structure, etc. The current collector is an important component of lithium-ion batteries. The metal foil current collector accounts for a certain proportion of the battery weight, which not only accounts for a large amount of cost, but also restricts the further improvement of battery energy density.
[0004] The functional current collector (multilayer current collector) currently commonly used in the battery field has a three-layer structure, including a metal conductive layer-a polymer support layer-a metal conductive layer. It uses an insulating polymer film as a support material, and metal is covered on both sides of the support material as the intermediate layer by magnetron sputtering + water electroplating, one-time evaporation or multiple evaporation methods. The metal is separated by the intermediate layer material. When applied to the battery, an additional transfer welding process is required. In addition, the metal layer is prone to shedding and stratification during the use of the battery after immersion in the electrolyte, activation pre-charging, and cycling, which leads to a drop in battery capacity and failure. Summary of the invention
[0005] The object of the present invention is to provide a riveted multi-layer current collector and a preparation method thereof, an electrode sheet and a battery to prevent the metal layer from falling off and stratifying.
[0006] To achieve the above purpose, the technical solution provided by the present invention is:
[0007] The first aspect of the present application provides a method for preparing a riveted multilayer current collector, comprising the following steps:
[0008] Step (1): connecting the first metal foil, the polymer substrate, and the second metal foil by roller welding to form a three-layer structure of the first metal foil layer - the polymer substrate layer - the second metal foil layer riveted together by roller welding;
[0009] Step (2): Pressing the three-layer structure of the first metal foil layer-polymer substrate layer-second metal foil layer to form a riveted multilayer current collector.
[0010] To optimize the above technical solutions, the specific measures taken also include:
[0011] The width of the first metal foil and the second metal foil is greater than the width of the polymer substrate, so that both sides of the polymer substrate can be wrapped by the metal foil, and the first metal foil and the second metal foil are connected to each other on both sides of the polymer substrate.
[0012] The first metal foil and the second metal foil are foils of the same material or foils of different materials.
[0013] In step (1), a welding roller integrated machine is used, and the first metal foil, the polymer substrate and the second metal foil are respectively installed in the welding roller integrated machine, and roller welding is performed after the belts are threaded.
[0014] Preferably, the welding roller integrated machine comprises three unwinding mechanisms, upper, middle and lower, which are respectively equipped with a first metal foil, a polymer substrate and a second metal foil; the welding tooth depth is 40-70 μm.
[0015] In step (2), the pressing is performed by constant roll gap pressing, and the roll gap of the constant roll gap pressing is 6-20 μm.
[0016] The surface of the obtained riveted multilayer current collector has an uneven structure. Furthermore, the maximum thickness of the riveted multilayer current collector after pressing does not exceed the total thickness of the first metal foil, the polymer substrate and the second metal foil plus 2 μm.
[0017] The second aspect of the present application provides a riveted multilayer current collector, comprising a first metal foil layer, a second metal foil layer on both sides and a polymer substrate layer in the middle, wherein the first metal foil layer, the second metal foil layer and the polymer substrate layer are connected by riveting, and the first metal foil and the second metal foil are respectively connected on both sides of the polymer substrate; the surface of the riveted multilayer current collector has an uneven structure formed by riveting.
[0018] The third aspect of the present application provides an electrode sheet, comprising the riveted multilayer current collector prepared by the method described in the first aspect of the present application or described in the second aspect of the present application.
[0019] The fourth aspect of the present application provides a battery, comprising the electrode sheet described in the third aspect of the present application.
[0020] Compared with the prior art, the present invention has the following beneficial effects:
[0021] The present invention provides a riveted multilayer current collector and a preparation method thereof, an electrode sheet and a battery. A first metal foil, a polymer substrate and a second metal foil are first riveted together by welding tooth roller welding to form a three-layer structure, and then pressed to make the connection between each layer more tightly and the overall thickness more uniform. The riveted connection method of welding tooth roller welding can make the connection between the two metal layers of the current collector and the sandwich polymer substrate more stable, and can prevent the metal layer from falling off.
[0022] The riveted multi-layer current collector of the present invention can increase the peeling force of the battery active material because of the uneven surface structure.
[0023] Both sides of the polymer substrate of the riveted multi-layer current collector of the present invention can be wrapped by metal foil, and compared with ordinary functional current collectors, the transfer welding process can be omitted in the battery manufacturing process.
[0024] The riveted multi-layer current collector of the present invention can improve the cycle performance of the battery and reduce the square resistance. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 : Schematic diagram of the preparation process of the present invention.
[0026] Figure 2 : Schematic diagram of the surface structure of the riveted multilayer current collector of the present invention.
[0027] Figure 3 : Schematic diagram of the cross-sectional structure of the riveted multilayer current collector of the present invention.
[0028] In the figure: 1-polymer substrate, 2-first metal foil, 3-second metal foil, 4-unwinding mechanism, 5-roller welding roller, 6-roller pressing roller, 7-winding mechanism, 8-metal layer, 9-polymer layer. DETAILED DESCRIPTION
[0029] The above contents of the present invention are further described in detail below in the form of embodiments, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the above contents of the present invention belong to the scope of the present invention.
[0030] The experimental methods used in the following examples are all conventional methods unless otherwise specified, and the reagents, methods and equipment used are all conventional reagents, methods and equipment in the technical field unless otherwise specified.
[0031] For the sake of simplicity, this document only specifically discloses some numerical values and optional ranges. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range. Similarly, any upper limit can be combined with any other upper limit to form an unambiguous range; the optional items in the optional range can also be combined arbitrarily.
[0032] Unless otherwise specified, the terms used in this application have the commonly known meanings generally understood by those skilled in the art. Unless otherwise specified, the numerical values of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art.
[0033] The present application provides a method for preparing a riveted multilayer current collector, such as Figure 1 As shown, the following steps are included:
[0034] Step (1): connecting the first metal foil 2, the polymer substrate 1, and the second metal foil 3 by means of a welding tooth roller welding to form a three-layer structure of the first metal foil layer-polymer substrate layer-second metal foil layer, and riveting the three-layer structure together by roller welding;
[0035] Step (2): Pressing the three-layer structure of the first metal foil layer-polymer substrate layer-second metal foil layer to form a riveted multilayer current collector.
[0036] The riveting referred to in this application is not the rivet connection in the field of mechanical devices in the macroscopic sense, but refers to the local metal depression of the metal foil by roller welding, and the tight connection between the metal foil layers on both sides and the substrate at the depression is produced at a relatively microscopic level.
[0037] In the present application, the first metal foil 2 and the second metal foil 3 are foils of the same material or foils of different materials.
[0038] The polymer substrate of the present application is an insulating material in the form of a thin film and plays a supporting role; the metal layer plays a conductive role.
[0039] The type of polymer substrate forming the polymer layer 9 in the present application can be selected from polymer materials such as polyethylene terephthalate (PET), polypropylene (PP), polyamide (PA), polyimide (PI), polyethylene (PE), polyvinyl chloride (PVC) and polystyrene (PS), and the solutions of the present application include but are not limited to the above-mentioned options.
[0040] The material types of the first metal foil 2 and the second metal foil 3 of the application can be selected from metals such as copper, aluminum, nickel, chromium or aluminum alloy, and the solutions of the present application include but are not limited to the above options.
[0041] In some embodiments, the thickness of the polymer substrate is between 3 μm and 12 μm.
[0042] In some embodiments, the thickness of the metal foil of the first metal foil and the second metal foil may be 1.5 μm to 3 μm.
[0043] In step (1), a welding roller integrated machine is used, and the first metal foil, the polymer substrate and the second metal foil are respectively installed in the welding roller integrated machine, and roller welding is performed after the belts are threaded.
[0044] In some embodiments, the polymer substrate and the metal foil are unwound in the form of a strip, and the metal foil and the polymer substrate rolls are pre-prepared and stored in an unwinding shaft of the welding roller integrated machine.
[0045] Preferably, the welding roller integrated machine comprises three unwinding mechanisms, namely, upper, middle and lower, which are respectively equipped with the first metal foil, the polymer substrate and the second metal foil.
[0046] The unwinding mechanism runs along a preset direction, the running direction is the length direction of the metal foil and polymer substrate roll, and the direction perpendicular to the length direction is the width direction of the metal foil and polymer substrate roll.
[0047] In some embodiments, the weld tooth depth is 40-70 μm.
[0048] Welding requires that the width of the two layers of metal foil is wider than the polymer film, that is, the width of the first metal foil and the second metal foil is greater than the width of the polymer substrate; the polymer film is sandwiched between the two layers of metal foil and riveted by welding so that both sides of the polymer substrate can be wrapped by the metal foil, and the first metal foil and the second metal foil are connected on both sides of the polymer substrate respectively.
[0049] In some embodiments, the edges of the aluminum foil on both sides of the polymer film extend beyond the edge of the polymer film by 20-100 μm.
[0050] In step (2), the pressing is performed by constant roll gap pressing.
[0051] In some embodiments, the constant gap roll pressing has a roll gap of 6-20 μm.
[0052] Preferably, the maximum thickness of the riveted multi-layer current collector after pressing does not exceed the total thickness of the first metal foil, the polymer substrate and the second metal foil plus 2 μm.
[0053] The obtained riveted multilayer current collector surface has an uneven structure, such as Figure 2 As shown, the peeling force of the electrode can be increased, and the overall structure of the riveted multi-layer current collector is as follows Figure 3 shown.
[0054] The present application also provides a riveted multilayer current collector, comprising a first metal foil layer, a second metal foil layer on both sides and a polymer substrate layer in the middle, wherein the first metal foil layer, the second metal foil layer and the polymer substrate layer are connected by riveting, and the first metal foil and the second metal foil are respectively connected on both sides of the polymer substrate; the surface of the riveted multilayer current collector has an uneven structure formed by riveting.
[0055] The present application provides an electrode sheet, comprising the above-mentioned riveted multi-layer current collector.
[0056] The present application provides a battery, comprising the above-mentioned electrode sheet.
[0057] The present invention is further described in detail below in conjunction with specific embodiments:
[0058] Example 1
[0059] The two prepared aluminum foils and polymer substrates are respectively installed on the upper, middle and lower unwinding mechanisms of the welding and rolling machine, and roller welding is performed after the belts are threaded; the polymer substrate is a polybutylene terephthalate (PET) base film with a thickness of 6μm; the thickness of the two aluminum foils is 2.5μm.
[0060] The aluminum foil on one side and the polymer substrate and the aluminum foil on the other side are welded together by welding teeth using an integrated welding roller machine; the total width of the two layers of aluminum foil is greater than the width of the polymer film, the polymer film is sandwiched between the two layers of metal foil, and the polymer film is located in the center, the edges of the aluminum foil on both sides of the polymer film extend beyond the edge of the polymer film by 20 mm, and riveted by roller welding, the depth of the welding teeth is 50 μm, the roller welding energy is 20 kJ, the amplitude is 10%, and the welding pressure is 0.15 MPa.
[0061] The roller-welded current collector is then roller-pressed through a constant roller gap with a roller gap of 8 μm. The surface of the prepared riveted multilayer current collector has an uneven structure, but the maximum thickness does not exceed 2 μm of the total thickness of the aluminum foil on one side + the polymer substrate + the aluminum foil on the other side.
[0062] The prepared riveted multilayer current collector was tested by a four-probe resistivity tester on the middle section of the current collector, including the area containing the polymer substrate layer, and its square resistance was measured to be 16.3 mΩ.
[0063] Example 2
[0064] The two prepared copper foils and polymer substrate are respectively installed on the upper, middle and lower unwinding mechanisms of the welding and rolling machine, and roller welding is performed after the belt is threaded; the polymer substrate is the same as that in Example 1; the polymer substrate is polyimide (PI) with a thickness of 4μm; the thickness of the two copper foils is 2.5μm.
[0065] Other steps and conditions are the same as in Example 1.
[0066] The prepared riveted multilayer current collector was tested by a four-probe resistivity tester on the middle section of the current collector, including the area containing the polymer substrate layer, and its square resistance was measured to be 9.7 mΩ.
[0067] Comparative Example 1
[0068] The same polymer-based material tape as in Example 1 is unwound in the form of a tape, which is prepared in advance and stored on an unwinding reel.
[0069] The surface of the polymer-based material strip is subjected to multiple evaporation by a multiple aluminum plating device, and multiple evaporation is performed on both sides of the polymer substrate to prepare a multi-layer aluminum current collector until the thickness reaches 1 μm.
[0070] The prepared multilayer aluminum current collector had a square resistance of 31.2 mΩ measured by a four-probe resistivity tester.
[0071] Comparative Example 2
[0072] The same polymer-based material tape as in Example 2 is unwound in the form of a tape, which is prepared in advance and stored on an unwinding reel.
[0073] The surface of the polymer-based material strip is subjected to multiple evaporation by a multiple copper plating device, and multiple evaporation is performed on both sides of the polymer substrate to prepare a multi-layer copper current collector until the thickness reaches 1 μm.
[0074] The prepared multilayer copper current collector had a square resistance of 21.1 mΩ measured by a four-probe resistivity tester.
[0075] Comparative Example 3
[0076] The materials used in this comparative example are the same as those in Example 1, and the preparation process is slightly different from that in Example 1, except that the aluminum foil on one side, the polymer substrate, and the aluminum foil on the other side are welded together by welding teeth and then rolled without passing through a constant roller gap, and the rest is the same as in Example 1; the riveted multilayer current collector prepared in this comparative example has an uneven structure on the surface, and the protrusions are relatively uneven, and the maximum thickness of the current collector is 34 μm, which exceeds the total thickness of the aluminum foil on one side + the polymer substrate + the aluminum foil on the other side + 2 μm.
[0077] The square resistance was measured by a four-probe resistivity tester and was 22.6 mΩ.
[0078] Comparative Example 4
[0079] The materials used in this comparative example are the same as those in Example 2, and the preparation process is slightly different from that in Example 2, except that the copper foil on one side, the polymer substrate, and the copper foil on the other side are welded together by welding teeth and then rolled without passing through a constant roller gap, and the rest is the same as in Example 1; the riveted multilayer current collector prepared in this comparative example has an uneven structure on the surface, and the protrusions are relatively uneven, and the maximum thickness of the current collector is 37 μm, which exceeds the total thickness of the copper foil on one side + the polymer substrate + the copper foil on the other side + 2 μm.
[0080] The square resistance was measured by a four-probe resistivity tester and was 15.4 mΩ.
[0081] Table 1 Test results of embodiments and comparative examples
[0082]
[0083] The square resistance is measured by a four-probe resistivity tester.
[0084] Analysis of test results:
[0085] From the above data comparison, it can be seen that the three-layer structure of Example 1 and Example 2, which is rolled and riveted and then pressed into one, is superior to the functional current collectors of Example 1 and Example 2, which are made by traditional processes, in terms of square resistance, resistance to electrolyte immersion, electrode peeling force and cycle performance.
[0086] The three-layer riveted structure functional current collector of the present invention can avoid the falling off of the metal layer, improve the cycle performance of the battery, and reduce the square resistance of the current collector; the riveted multi-layer current collector can increase the peeling force of the active material because the surface has an uneven structure; because both sides of the polymer substrate can be wrapped with metal foil, the riveted multi-layer current collector can also save the transfer welding process in the battery manufacturing process.
[0087] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the profession, without departing from the scope of the technical solution of the present invention, according to the technical essence of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.
Claims
1. A method for preparing a riveted multilayer current collector, characterized in that: The following steps are involved: Step (1): connecting the first metal foil, the polymer substrate, and the second metal foil by roller welding to form a three-layer structure of the first metal foil layer - the polymer substrate layer - the second metal foil layer riveted together by roller welding; Step (2): Pressing the three-layer structure of the first metal foil layer-polymer substrate layer-second metal foil layer to form a riveted multilayer current collector.
2. The method for preparing a riveted multilayer current collector according to claim 1, characterized in that: The width of the first metal foil and the second metal foil is greater than the width of the polymer substrate, so that both sides of the polymer substrate can be wrapped by the metal foil, and the first metal foil and the second metal foil are connected to each other on both sides of the polymer substrate.
3. The method for preparing a riveted multilayer current collector according to claim 1, characterized in that: The first metal foil and the second metal foil are foils of the same material or foils of different materials.
4. The method for preparing a riveted multilayer current collector according to claim 1, characterized in that: In step (1), a welding roller integrated machine is used, and the first metal foil, the polymer substrate and the second metal foil are respectively installed in the welding roller integrated machine, and roller welding is performed after the belts are threaded.
5. The method for preparing a riveted multi-layer current collector according to claim 4, characterized in that: The welding roller integrated machine comprises three unwinding mechanisms, upper, middle and lower, which are respectively equipped with a first metal foil, a polymer substrate and a second metal foil; the welding tooth depth is 40-70 μm.
6. The method for preparing a riveted multi-layer current collector according to claim 1, characterized in that: In step (2), the pressing is performed by constant roll gap pressing, and the roll gap of the constant roll gap pressing is 6-20 μm.
7. The method for preparing a riveted multi-layer current collector according to claim 1, characterized in that: The surface of the obtained riveted multilayer current collector has an uneven structure, and the maximum thickness of the riveted multilayer current collector after pressing does not exceed the total thickness of the first metal foil, the polymer substrate and the second metal foil plus 2 μm.
8. A riveted multilayer current collector, characterized in that: It comprises a first metal foil layer and a second metal foil layer on both sides and a polymer substrate layer in the middle. The first metal foil layer, the second metal foil layer and the polymer substrate layer are connected by riveting, and the first metal foil and the second metal foil are connected on both sides of the polymer substrate respectively; the surface of the riveted multilayer current collector has an uneven structure formed by riveting.
9. An electrode sheet, characterized in that: A riveted multilayer current collector prepared by the method of any one of claims 1 to 7 or as described in claim 8.
10. A battery, characterized in that: The electrode sheet comprising claim 9.