Composite foil material processing method, processing device and composite foil material

Abstract

The invention discloses a composite foil material processing method and device and a composite foil material, and belongs to the technical field of conductive films.The processing method comprises the following steps that the composite foil material is provided and comprises a polymer layer and metal layers formed on the two sides of the polymer layer; a communication hole is formed in the composite foil tab welding area, the communication hole penetrates through the metal layer, and the polymer layer is communicated with the outside through the communication hole; and extruding at the communicating hole to form an inner concave part so as to thin the polymer layer and form electrical conduction between the metal layers at the two sides. According to the processing method of the composite foil, on the basis of processing the communicating hole and extruding to form the inner concave part, electrical conduction of the metal layer is realized, and meanwhile, part of the polymer layer overflows to the outer side of the metal layer from the communicating hole under the extrusion effect and is flatly laid to the outer side of the metal layer under the cooperation of the extrusion effect; protruding or cracking of the metal layer caused by extrusion stress generated on the polymer layer and the metal layer on the side face of the extrusion site can be avoided.

Description

Technical Field

[0001] The invention relates to the technical field of composite film materials, and in particular to a composite foil material processing method, a processing device and a composite foil material. Background Art

[0002] Currently, composite foil is often used as a current collector. The structure of the composite foil is a sandwich structure with a polymer layer in the middle and metal layers on both sides of the polymer layer.

[0003] The polymer layer in the composite foil has the advantages of high tensile strength, soft texture and thin coating, so it is not easy to have burrs. Even if burrs appear, the possibility of piercing the diaphragm is relatively small due to its soft texture and thin coating, which can effectively prevent short circuits inside the battery and improve the safety performance of the battery.

[0004] However, due to the non-conductivity of the middle polymer layer, the current common practice is to use ultrasonic transfer welding. The working principle of this welding method is to pressurize and vibrate the welding head at the welding point of the pole ear, so that the transfer body (usually foil) is welded to the metal layer of the current collector, and then the transfer body is welded to make the upper and lower metal layers conductive.

[0005] However, the transfer welding method has high requirements on welding process. The high-frequency vibration of the welding head may cause the metal layer of the composite foil at the welding point to crack and fall off, which will increase the internal resistance.

[0006] Therefore, further improvements are needed. Summary of the invention

[0007] 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 method for processing a composite foil material, which can achieve conduction of metal layers on both sides of the composite foil material by thinning and reduce damage to the metal layers.

[0008] Another object of the present invention is to provide a device for use in the above processing method;

[0009] Another object of the present invention is to provide the above-mentioned composite foil.

[0010] The technical solution of the present invention is as follows:

[0011] A method for processing a composite foil material, the method is as follows:

[0012] Providing a composite foil comprising a polymer layer and metal layers formed on both sides of the polymer layer;

[0013] A connecting hole is formed in the welding area of ​​the composite foil tab, the connecting hole penetrates the metal layer, and the polymer layer is connected to the outside through the connecting hole;

[0014] An inner concave portion is formed by extrusion at the connecting hole to thin the polymer layer and to form electrical conduction between the metal layers on both sides.

[0015] Based on the above technical solution, connecting holes are processed and extruded to form inner concave portions to achieve electrical conductivity of the metal layer. At the same time, the polymer layer can be caused to partially overflow from the connecting holes to the outside of the metal layer under the action of extrusion, and spread to the outside of the metal layer in coordination with the extrusion action, thereby avoiding extrusion stress on the polymer layer and the metal layer on the side of the extrusion site, which may cause bulging or cracking of the metal layer. The overflowed polymer can also be used as a bonding aid for subsequent further welding of the tabs.

[0016] Furthermore, the polymer layer material is 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.

[0017] Based on the above technical solution, the polymer material is a conventional commercially available polymer material and is easy to obtain.

[0018] Further, the thickness of the polymer layer is set to 3-20 μm.

[0019] Based on the above technical solution, the polymer layer is relatively thin, which can reduce the thickness of the subsequent electrode process and is also conducive to forming electrical conduction after extrusion.

[0020] Furthermore, the metal layer is nickel, chromium, titanium, aluminum, copper, silver or gold.

[0021] Furthermore, the thickness of the metal layer is set to 0.5-1.5 μm.

[0022] Based on the above technical solution, when used as a conductive film or current collector, a suitable thickness is selected to facilitate local thinning.

[0023] Furthermore, the communicating hole is a hole that does not penetrate through or entirely penetrates through the foil.

[0024] Furthermore, the opening size of the connecting hole is 0.5-2 mm, and the opening area accounts for 5%-20% of the inner recess.

[0025] Based on the above technical solution, the size of the opening is selected in combination with the size of the inner concave portion, and the opening area is small, which will not cause too much damage to the composite foil.

[0026] Furthermore, heating is performed at the extrusion point.

[0027] Based on the above technical solution, heating can soften the polymer layer, which is beneficial to displacement during extrusion. Under heating conditions, the polymer recrystallizes and shrinks, which makes it easier to reduce the volume at the extrusion position, making it easier for the metal layers on both sides to approach and form electrical conduction. The polymer overflowing from the connecting hole forms an anchor for the metal layer after cooling, which can also prevent the metal layer from cracking and delamination.

[0028] Further, an inner concave portion is formed by extrusion on one side of the composite foil; and / or, an inner concave portion is formed on both sides.

[0029] Based on the above technical solution, the processing method can be selected in combination with the adaptability of the foil thickness to adapt to different polymer layer thicknesses.

[0030] Furthermore, the overlapping area of ​​the metal layers at the inner recess is greater than 15%.

[0031] Based on the above technical solution, good electrical conduction can be achieved.

[0032] A composite foil processing device includes an extrusion assembly, which is arranged corresponding to the composite foil tab welding area. The extrusion assembly includes a first displacement unit and a second displacement unit, and at least one displacement unit is provided with a protruding die head for acting on the composite foil surface to form an inner concave portion.

[0033] Furthermore, the displacement unit is configured as a rotating roller body, a convex die head is arranged on the upper circumference of the roller body, and an outer end side of the die head has an extrusion surface to provide a sufficient extrusion action surface during extrusion;

[0034] Alternatively, the displacement unit is configured as an upper die and a lower die that are intermittently displaced toward the foil, and the die head is disposed inside the die.

[0035] Further, the roller body is configured as a heating roller.

[0036] A composite foil material comprises a polymer layer and metal layers formed on both sides of the polymer layer;

[0037] A connecting hole is provided in the corresponding tab welding area of ​​the composite foil, and the connecting hole penetrates the metal layer so that the polymer layer is connected to the outside through the connecting hole;

[0038] The corresponding tab welding area is extruded to form an inner concave portion, the polymer layer forms a thinning area corresponding to the inner concave portion, and the metal layers on both sides of the polymer layer form electrical conduction in the thinning area;

[0039] Part of the polymer layer material in the thinning area overflows from the connecting hole to the surface of the metal layer in the inner concave part to form an anchoring layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A schematic diagram of a composite foil material having only a single set of inner recesses;

[0041] Figure 2 A schematic diagram of a composite foil material provided with a plurality of (two groups of) inner recesses;

[0042] Figure 3 It is a schematic diagram of the extrusion assembly acting on the foil;

[0043] Figure 4 A schematic diagram of the structure of one of the displacement units in the extrusion assembly.

[0044] In the figure: 0-ear welding area; 1-polymer layer; 11-thinning area; 2-metal layer; 3-connecting hole; 4-inner concave part; 41-anchoring layer;

[0045] 10-extrusion assembly; 101-first displacement unit; 102-second displacement unit; 103-die head; 1031-extrusion surface. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the contents 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.

[0047] Reference Figure 1 and Figure 3 A method for processing a composite foil material, the method is as follows:

[0048] Providing a composite foil comprising a polymer layer 1 and a metal layer 2 formed on both sides of the polymer layer;

[0049] A connecting hole 3 is formed in the composite foil tab welding area 0, the connecting hole 3 penetrates the metal layer 2, and the polymer layer 1 is connected to the outside through the connecting hole 3;

[0050] An inner concave portion 4 is formed by extrusion at the connecting hole 3 to thin the polymer layer 1 and to form electrical conduction between the metal layers 2 on both sides.

[0051] Connecting holes are provided and an inner concave portion is formed by extrusion. During this process, the polymer layer can be caused to produce (plastic) deformation and displacement under the action of extrusion, and partially overflow from the connecting holes to the outside of the metal layer, and cooperate with the extrusion action to be spread to the outside of the metal layer. This can prevent the polymer layer from moving toward the side of the extrusion site due to the extrusion action during the extrusion process, thereby preventing the polymer layer and the metal layer on the side of the extrusion site from generating extrusion stress, causing the metal layer to bulge or crack. The overflowed polymer can also be used as a bonding aid for the subsequent further welding of the pole ear.

[0052] Among them, the material of the polymer layer 1 is 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; its thickness is set to 3-20 μm, preferably 4-8 μm; it is not specifically limited in the present application, but it should not be too thick, otherwise it will greatly increase the thickness of the subsequent electrode process, and it is not conducive to the formation of electrical conduction after extrusion; of course, the thickness of the polymer layer 1 should not be too thin, which will affect the strength of the overall foil and is not conducive to processing.

[0053] The metal layer 2 is a conductive metal such as nickel, chromium, titanium, aluminum, copper, and silver. When used as a current collector, it is mostly aluminum and copper. Its thickness can be selected according to needs. Technical personnel in this field can make reasonable settings based on the usage scenario and the required current carrying capacity. When used as a conductive film or current collector, and considering that the inner concave portion 4 is locally thinned after being extruded, the thickness of the metal layer 2 should not be too small, and is generally set to 0.5-1.5μm.

[0054] Furthermore, the size of the inner recess 4 matches the welding area of ​​the electrode tab to be welded, such as being evenly distributed in the area to be welded, or being slightly larger than the area to be welded; the number of the inner recess 4 can be single ( Figure 1 ), that is, the inner concave portion 4 can cover the area to be welded, or it can be set as a plurality of ( Figure 2 ), select based on the welding area and the size of the connecting hole;

[0055] The formation of the connecting hole 3 can be based on physical needling (needle roller) or laser or chemical etching (based on mask); in order to simplify the hole opening process, the connecting hole can also be a whole through the foil; the size and number of the openings can actually be adaptively selected in combination with the area of ​​the welding area, such as the hole size is about 0.5-2mm, and the hole area accounts for 5%-20% of the inner concave part.

[0056] The shape of the inner concave portion 3 is mainly based on the die head during extrusion, and the cross-sectional shape can be a polygon such as a trapezoid, and its end has a horizontal surface to have a certain extrusion area.

[0057] Furthermore, heating can be performed at the extrusion point, and the heating temperature can soften the polymer layer. At the same time, the temperature should be avoided to be higher than the decomposition temperature of the polymer material; the temperature can be selected in combination with the polymer material, such as setting the temperature to 60-200°C, preferably 80-150°C.

[0058] The softened polymer layer is prone to softening displacement during extrusion, and under heating conditions, the polymer recrystallizes and shrinks, which makes it easier to reduce the volume at the extrusion position, making it easier for the metal layers on both sides to approach each other and form electrical conduction; and after heating, the polymer overflowing from the connecting hole forms an anchoring layer 41 for the metal layer after cooling, which can also prevent the metal layer from cracking and delamination; due to the formation of the anchoring layer 41, during the subsequent transfer welding, when the welding head acts on the anchoring layer (high-frequency reciprocating displacement, frictional heat generation), the polymer softens or melts and fills the gap between the metal layer 2 and the welding material (metal foil for transfer welding), and crystallizes after cooling to form an anchoring effect, which has an adhesion enhancement effect on the welding material.

[0059] For the matching inner recesses formed on the upper and lower sides of the polymer layer, in order to achieve good electrical conduction, there should be a certain overlapping area, preferably with an overlapping area of ​​more than 15%, that is, at this time, the matching inner recesses 4 can be staggered up and down (not shown in the drawings); of course, it can also correspond to only the welding side of the welding area, such as welding on the upper side during the welding of the tab, and only one group of inner recesses needs to be formed so that it can be close to the metal layer below (not shown in the drawings) to achieve electrical conduction between the upper and lower metal layers; the depths of the upper and lower inner recesses formed after extrusion can be basically the same, or there can be differences.

[0060] In addition, the inner concave portion is formed by pressing the protrusion or the pressure-bearing platform, which can be formed by pressing the upper and lower extrusion dies, or by rolling the roller with a protruding die.

[0061] Therefore, if Figure 3 and Figure 4 As shown, the present application also discloses a device for processing the above-mentioned composite foil, including an extrusion assembly 10, the extrusion assembly 10 is arranged corresponding to the composite foil tab welding area 0, the extrusion assembly 10 includes a first displacement unit 101 and a second displacement unit 102, and at least one displacement unit is provided with a protruding die head 103, which is used to act on the surface of the composite foil to form an inner concave portion. The number and arrangement of the die heads 103 can be set in combination with the size and number of the inner concave portions.

[0062] The displacement unit is configured as a rotating roller, a raised die head 103 is mounted on the upper side of the roller, and an extrusion surface 1031 is provided on the outer end of the die head 103 to provide a sufficient extrusion action surface during extrusion; at this time, the distance between the rollers is sufficient to allow the foil to pass freely.

[0063] Of course, the displacement unit can also be configured as an upper mold and a lower mold that are intermittently displaced toward the foil material, and a concave portion is formed on the foil material after the molds are closed.

[0064] The roller body can be configured as a heating roller to heat the foil during rolling.

[0065] The present application also discloses a composite foil prepared based on the above scheme, referring to Figure 1 and Figure 2 , which includes a polymer layer 1 and a metal layer 2 formed on both sides of the polymer layer;

[0066] A connecting hole 3 is provided corresponding to the tab welding area 0 of the composite foil, and the connecting hole 3 penetrates the metal layer 2, so that the polymer layer 1 is connected to the outside through the connecting hole 3;

[0067] The corresponding tab welding area 0 is extruded to form an inner concave portion 4, the polymer layer forms a thinning area 11 corresponding to the inner concave portion 4, and the metal layers 2 on both sides of the polymer layer are electrically connected in the thinning area 11;

[0068] Part of the polymer layer material in the thinned area 11 overflows from the connecting hole 3 to the surface of the metal layer 2 in the inner recess 4 to form an anchoring layer 41 .

[0069] In this application, structures and connection relationships that are not described in detail are all prior arts, and their structures and principles are well-known technologies and will not be described in detail here.

[0070] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are 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 direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0071] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like 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 a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0072] 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 method for processing a composite foil, characterized in that: Here’s how: Providing a composite foil comprising a polymer layer and metal layers formed on both sides of the polymer layer; A connecting hole is formed in the welding area of ​​the composite foil tab, the connecting hole penetrates the metal layer, and the polymer layer is connected to the outside through the connecting hole; An inner concave portion is formed by extrusion at the connecting hole to thin the polymer layer and to form electrical conduction between the metal layers on both sides.

2. The method for processing a composite foil according to claim 1, characterized in that: The thickness of the polymer layer is 3-20 μm; The thickness of the metal layer is set to 0.5-1.5 μm.

3. The method for processing a composite foil according to claim 1, characterized in that: The communicating hole is a hole that does not penetrate or completely penetrates the foil; Among them, the opening size of the connecting hole is 0.5-2mm, and the opening area accounts for 5%-20% of the inner concave part.

4. The method for processing a composite foil according to claim 1, characterized in that: Heat is applied at the extrusion point.

5. The method for processing a composite foil according to claim 1, characterized in that: The inner concave portion is formed by extrusion on one side of the composite foil; and / or, the inner concave portion is formed on both sides.

6. The composite foil according to claim 5, characterized in that: The overlapping area of ​​the metal layers at the inner concave portion is more than 15%.

7. A composite foil processing device, used for processing composite foil according to any one of claims 1 to 6, characterized in that: It includes an extrusion component, which is arranged corresponding to the composite foil tab welding area. The extrusion component includes a first displacement unit and a second displacement unit, and at least one displacement unit is provided with a protruding die head for acting on the surface of the composite foil to form an inner concave portion.

8. The composite foil processing device according to claim 7, characterized in that: The displacement unit is configured as a rotating roller body, a convex die head is arranged on the upper circumference of the roller body, and an extrusion surface is provided on the outer end side of the die head to provide a sufficient extrusion action surface during extrusion; Alternatively, the displacement unit is configured as an upper die and a lower die that are intermittently displaced toward the foil, and the die head is disposed inside the die.

9. The composite foil processing device according to claim 8, characterized in that: The roller body is configured as a heating roller.

10. A composite foil material, processed according to any one of claims 1 to 6, characterized in that: include: a polymer layer and metal layers formed on both sides of the polymer layer; A connecting hole is provided in the corresponding tab welding area of ​​the composite foil, and the connecting hole penetrates the metal layer so that the polymer layer is connected to the outside through the connecting hole; The corresponding tab welding area is extruded to form an inner concave portion, the polymer layer forms a thinning area corresponding to the inner concave portion, and the metal layers on both sides of the polymer layer form electrical conduction in the thinning area; Part of the polymer layer material in the thinning area overflows from the connecting hole to the surface of the metal layer in the inner concave part to form an anchoring layer.

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