Composite current collector
By setting the neutral layer and concave area in the bending area of the composite fluid collection and using metal or metal oxide filling area, the problem of delamination and cracking of the base film layer during bending is solved, and the composite fluid collection is improved mechanical strength and processability.
Patent Information
- Application Number
- CN202411284621.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-13
- Publication Date
- 2024-12-27
AI Technical Summary
When the composite fluid is used in the winding battery process, the base film layer is prone to stress during bending, resulting in the risk of delamination and cracking.
A neutral layer is provided in the bending area of the composite fluid collection, the connection interface between the conductive layer and the support layer is close to the neutral layer, and a concave area is formed in the bending area to increase the anchoring effect, and the filling area is filled with metal or metal oxides to improve the Adhesion and strength.
It effectively reduces the risk of delamination between the conductive layer and the support layer after bending, avoids slippage and deformation, ensures the flatness and adhesion of the conductive layer, and improves the mechanical strength and processability of the composite fluid collection.
Smart Images
Figure CN119208615A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of current collectors, and in particular to a composite current collector. Background Art
[0002] The composite current collector is a composite polymer material with metal coated on the surface. Common processing methods include vacuum evaporation, which uses polymer film as a carrier to evaporate metal targets.
[0003] In the process of using it as a wound battery, the pole piece coated with active material needs to be bent, and the composite current collector needs to be bent or folded in the process. Since the base film layer is a single polymer material layer, stress will be generated when bending occurs, and there may be a risk of delamination and cracking. Summary of the invention
[0004] The present invention aims to solve one of the technical problems in the related art to at least some extent. To this end, one object of the present invention is to provide a composite current collector, wherein the connection interface between the conductive layer and the support layer in the bending region is arranged at or near the neutral layer of the bending region, so as to reduce the risk of delamination and cracking of the conductive layer caused by bending stress after bending.
[0005] The technical solution of the present invention is as follows:
[0006] A composite current collector comprises a support layer, the surface of which forms a first conductive layer; the connection interface between the first conductive layer and the support layer in the bending area is arranged at the neutral layer of the entire film or at a position near the neutral layer.
[0007] Based on the above technical solution, after bending, the connection interface between the conductive functional layer and the support layer in the bending area can be in a low stress area, thereby avoiding problems such as delamination or cracking after delamination.
[0008] Furthermore, a region is formed in the support layer corresponding to the bending direction, the surface height of the region is lower than the surface height of the support layer, and the connection interface between the first conductive layer and the support layer is arranged on the surface of the region.
[0009] Based on the above technical solution, the connection interface between the first conductive layer and the supporting layer in the bending zone can be made close to the neutral layer; the setting of the concave area can also increase the anchoring effect of the first conductive layer corresponding to the bending zone, so that it can cooperate with the supporting layer and the filling zone membrane layer during the bending process, making it less likely to slip and avoiding delamination to a certain extent.
[0010] Furthermore, the first conductive layer corresponding to the bending area also includes a filling area, and the filling area is filled in the region to form a conductive area on the surface of the filling area.
[0011] Based on the above technical solution, a segmented filling structure can be formed in the bending area, which is easy to process.
[0012] Furthermore, the conductive area is substantially flush with the surface of the first conductive layer in other areas.
[0013] Based on the above technical solution, the conductive layer formed in the bending area and the conductive layers in other areas can form a relatively flat film surface.
[0014] Furthermore, an interface is provided between the filling region and the conductive region, and an adhesion force of the conductive layer in the conductive region at the interface is greater than an adhesion force between the conductive layer and the supporting layer.
[0015] Based on the above technical solution, it can be ensured that delamination is not easy to occur at the interface between the conductive area and the filling area after bending.
[0016] Furthermore, the support layer is made of polymer film material.
[0017] Furthermore, the thickness of the support layer is set to 3-20 μm.
[0018] Based on the above technical solution, the thickness of the support layer is controlled, which is beneficial to the subsequent continuous processing, and the overall thickness of the composite current collector can be controlled at the same time.
[0019] Furthermore, the depth of the formed concave area does not exceed 1 / 3 of the thickness of the support layer.
[0020] Furthermore, the depth of the concave area does not exceed 1 / 4 of the thickness of the support layer.
[0021] Based on the above technical solution, by controlling the thickness of the area, on the one hand, it is possible to avoid affecting the strength of the support layer and ensure the processability and overall mechanical strength; on the other hand, the setting of the neutral layer itself is also close to the bending direction side. Therefore, the connection interface between the relatively thinner area and the support layer is close to the neutral layer.
[0022] Furthermore, the filling region is metal; and / or metal oxide.
[0023] Based on the above technical solution, good bonding force can be achieved at the interface, which is much greater than the bonding force with the support layer.
[0024] Furthermore, the filling area material is a bonding enhancement layer.
[0025] Furthermore, the bonding enhancement layer includes a primer layer.
[0026] Based on the above technical solution, the bonding reinforcement material is selected for the filling area, which can improve the bonding strength with the base layer while ensuring the bonding strength with the conductive area material.
[0027] Furthermore, fillers are filled in the primer layer.
[0028] Based on the above technical solution, the strength and modulus of the filling area can be increased to avoid the problem of slip and delamination at the interface; it can also play a shape-preserving role, so that the bending area is not easily deformed after subsequent bending.
[0029] Furthermore, the filler is metal or conductive non-metal particles.
[0030] Based on the above technical solution, the conductive performance of the bending zone can be increased and improved.
[0031] Furthermore, a second conductive layer is formed on a side away from the bending direction. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:
[0033] Figure 1 It is a schematic diagram of the cross-sectional structure of the composite current collector bending part;
[0034] Figure 2 It is a schematic diagram of the cross-sectional structure of the composite current collector when it is flattened;
[0035] Figure 3 This is a schematic diagram of the cross-sectional structure of another embodiment of the composite current collector when flattened.
[0036] In the figure:
[0037] 1-support layer; 11-area;
[0038] 2-first conductive layer; 21-filling area; 22-conductive area; 23-interface;
[0039] 3- second conductive layer;
[0040] 4-neutral layer;
[0041] 10-bending zone;
[0042] 20-Non-bending area.
[0043] Figure 2 The horizontal direction corresponds to the longitudinal direction of the composite current collector. DETAILED DESCRIPTION
[0044] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.
[0045] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.
[0046] In the prior art, due to the different bending radii of the metal layer and the polymer layer, the stress generated on the metal layer due to bending is greater. On the inner side of the bending area, due to the smaller bending radius, the stress between the base film and the conductive layer on the bending side is greater, the problem of stress concentration is serious, and it is easy to crack or delaminate.
[0047] In response to the above problems, in some embodiments of the present application, a composite current collector is proposed, including a support layer 1, a first conductive layer 2 is formed on the surface of the support layer; the connection interface between the first conductive layer 2 and the support layer 1 in the bending zone 10 is arranged at the neutral layer 4 of the entire film or near the neutral layer 4.
[0048] Among them, when the composite current collector is bent, the outer layer is stretched and the inner layer is squeezed. There is a transition layer on its cross section that is neither stretched nor compressed, and the stress is almost zero. This transition layer is called the neutral layer of the material.
[0049] Based on the above technical solution, after bending, the connection interface 23 between the conductive functional layer and the support layer in the bending area can be in a low stress area, thereby avoiding problems such as delamination or cracking after delamination.
[0050] In some embodiments of the present application, reference Figure 1 and Figure 2 , a region 11 is formed in the support layer 1 corresponding to the bending direction, and the surface height of the region 11 is lower than the surface height of the support layer 1. Obviously, the concave surface of the region 11 is close to the neutral layer 4;
[0051] At this time, the first conductive layer 2 corresponding to the bending area 10 also includes a filling area 21, and the filling area 21 is filled in the area 11, that is, the filling area 21 forms a connection interface with the surface of the supporting layer 1 in the area 11, and further forms a conductive area 22 on the surface of the filling area 21, and the conductive area 22 is basically flush with the surface of the first conductive layer 2 in other areas; then, a complete conductive area is formed together with the conductive layer of the non-bending area 20, and there is an interface 23 between the filling area 21 and the conductive area 22. Obviously, the adhesion of the conductive layer in the conductive area 22 at the interface 23 is preferably greater than the adhesion between the conductive layer and the supporting layer 1, so as to ensure that delamination is not easy to occur at the interface 23 after bending.
[0052] The setting of area 11 can also increase the anchoring effect of the first conductive layer 2 corresponding to the bending area 10, so that it cooperates with the support layer 1 and the film layer of the filling area 21 during the bending process, is not prone to slippage, and can also avoid delamination to a certain extent.
[0053] The material of the support layer 1 can be a polymer film material commonly used in the prior art, such as at least one of polyamide, polyethylene terephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, poly(p-phenylene terephthalamide), polypropylene, polyoxymethylene, polytetrafluoroethylene or polycarbonate, preferably polypropylene (PP), polyethylene terephthalate (PET), polyimide (PI) or a composite film thereof; the thickness is set to 3-20 μm, preferably 4-12 μm.
[0054] The depth of the formed concave region 11 is preferably no more than 1 / 3 of the thickness of the support layer 1, and more preferably no more than 1 / 4 of the thickness of the support layer. Controlling the thickness of the region 11 can, on the one hand, avoid affecting the strength of the support layer 1 and ensure processability and overall mechanical strength; on the other hand, the neutral layer 4 is also arranged close to the bending direction, so the relatively thinner region 11 has a connection interface with the support layer 1 close to the neutral layer 4.
[0055] In some embodiments of the present application, the filling area 21 is a conductive layer of the same material as the conductive area; it can be formed by evaporation. The conductive area 22 is formed after the first conductive layer 2 corresponding to the bending area is target material evaporated, and it has good bonding force at the interface 23, which is much greater than the bonding force with the support layer 1.
[0056] In some embodiments of the present application, the formation of the first conductive layer 2 in the bending area 10 can be controlled by controlling the deposition amount of evaporation, such as reducing the vehicle speed to increase the deposition amount and obtain a locally larger coating thickness.
[0057] In addition, the second conductive layer 3 may also be formed on the side away from the bending direction.
[0058] The thickness of the conductive layer can be set according to actual needs, such as controlling the thickness of the conductive layer according to the required square resistance. The conductive layer can be made of metal, such as copper, aluminum, nickel, chromium, etc.
[0059] Reference Figure 3 The main difference is that the filling area 21 in the region 11 is a filler of different components.
[0060] In some embodiments of the present application, the filling area 21 is a coating material, which is formed in the area 11 after coating (curing), and then the conductive area 22 is attached to the surface of the supporting layer 1 and the filling area 21 by means of plating, so as to form a complete first conductive layer 2.
[0061] Among them, the material of the filling area 21 is selected as an adhesion enhancement layer; the adhesion enhancement layer can select a coating material with better affinity with the target material, such as various primer layers, including adhesive components such as polyvinylidene fluoride, polytetrafluoroethylene, SBR, water-based epoxy resin, polyacrylic resin, polyvinyl alcohol, etc., wherein 3%-10% of the adhesive mass is added to the solid particle filler, and the filler is selected from metals (such as aluminum, copper, silver, titanium, chromium, nickel, etc.) and / or non-metals (carbon-based fillers such as graphite) with a particle size of 100-500nm, and is diluted to an appropriate viscosity by a suitable solvent (water, ethyl acetate or alcohol, etc.) and then coated (the viscosity can be selected in combination with the thickness adaptability of the coating). The cured adhesion enhancement layer is used as the filling area 21, which can improve the bonding performance with the conductive area 22; at the same time, the setting of the particle filler can increase the strength and modulus of the filling area, making it less likely to deform and avoiding the problem of delamination at the interface 23.
[0062] You can also choose to plate metals or their oxide materials that have good affinity with the target material, such as aluminum oxide, nickel, chromium and other materials.
[0063] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the drawings or conventionally expressed in the prior art, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply 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 understood as limiting the present invention.
[0064] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.
[0065] The term "multiple" as used in this application refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple sheets" refers to more than two sheets (including two sheets).
[0066] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.
Claims
1. A composite current collector, characterized in that: It comprises a supporting layer, at least a first conductive layer is formed in a surface corresponding to a bending area of the supporting layer, and a connection interface between the first conductive layer and the supporting layer is arranged in a neutral layer of the entire film or in a position near the neutral layer.
2. The composite current collector according to claim 1, characterized in that: A region is formed in the support layer corresponding to the bending area, the surface height of the region is lower than the surface height of the support layer, and the connection interface between the first conductive layer and the support layer is arranged on the surface of the region.
3. The composite current collector according to claim 1, characterized in that: The first conductive layer is provided with a filling area corresponding to the bending area, the filling area is filled in the region, and a conductive area is formed on the surface of the filling area.
4. The composite current collector according to claim 3, characterized in that: The conductive area in the bending area is substantially flush with the surface of the first conductive layer in other areas; And / or, the adhesion of the conductive layer at the interface in the conductive region is greater than the adhesion between the conductive layer and the support layer.
5. The composite current collector according to claim 1, characterized in that: The support layer is made of polymer film material; And / or, the thickness of the support layer is set to 3-20 μm.
6. The composite current collector according to claim 5, characterized in that: The depth of the formed concave area does not exceed 1 / 3 of the thickness of the support layer.
7. The composite current collector according to any one of claims 1 to 6, characterized in that: The filling area material is metal and / or metal oxide; Alternatively, the filling region material is a bonding enhancement layer.
8. The composite current collector according to claim 7, characterized in that: The bonding enhancement layer includes a primer layer.
9. The composite current collector according to claim 8, characterized in that: Fill the primer layer with filler.
10. The composite current collector according to claim 9, characterized in that: The filler is metal or conductive non-metal particles.