Manufacturing system for composite aluminum foil film

Abstract

The application discloses a manufacturing system for a composite aluminum foil film, which comprises at least a base material feeding roller for conveying a base material layer, a pair of aluminum foil feeding rollers for conveying metal aluminum foil to both sides of the base material layer, and a pair of protection film feeding rollers for conveying a rolling protection film to the outer side of the metal aluminum foil; a film layer composed of the base material layer, the metal aluminum foil and the rolling protection film is provided with at least one pair of rolling rollers on both sides along the advancing direction of the film layer; a pair of mold rollers for forming holes on both sides of the film layer is arranged downstream of the rolling rollers; and a receiving roller for the composite aluminum foil film is arranged downstream of the mold rollers. The manufacturing system can be used for continuously processing the composite aluminum foil film, and can be used for preparing a low-thickness composite aluminum foil film which is rolled and stretched after being compounded, so that the defect that a low-thickness metal aluminum foil is difficult to compound is avoided, and thinner metal aluminum foil can be obtained while the conductivity and strength are ensured.

Description

Technical Field

[0001] This invention relates to the field of current collector manufacturing technology in lithium-ion batteries, and more particularly to a manufacturing system for composite aluminum foil films that can be used as positive electrode current collectors in lithium-ion batteries. Background Technology

[0002] The current collector in a lithium-ion battery consists of a conductive metal foil film. Its main function is to support the electrode materials of the positive and negative electrodes, while simultaneously collecting current and conducting electrons. Aluminum foil is commonly used for the positive electrode current collector, and copper foil for the negative electrode. To improve the energy density of the battery, composite current collectors made of plastic film and metal layer have emerged, such as composite aluminum current collectors used as the positive electrode and composite copper current collectors used as the negative electrode. The metal layer in composite current collectors can be formed by bonding metal foil to the plastic film, or by vapor deposition or sputtering processes. Metal foil has excellent conductivity but requires a relatively large thickness; sputtered and vapor-deposited metal layers are thinner, have poorer conductivity, require repeated deposition, have high process requirements, and repeated deposition of plastic films easily leads to wrinkles, resulting in a relatively poor yield.

[0003] For example, CN 114695900 B discloses a composite current collector, comprising a first aluminum foil layer, a PET layer, and a second aluminum foil layer stacked sequentially. Both the first and second aluminum foil layers are fixedly connected to the PET layer. The upper surface of the first aluminum foil layer has a plurality of first grooves, and the lower surface of the second aluminum foil layer has a plurality of second grooves. This prior art employs a relatively thick aluminum foil structure to obtain the grooves.

[0004] Then, the aluminum and copper foils used as current collectors are mainly for conductivity and do not participate in the active reaction. Therefore, one way to improve the energy density of batteries at present is to reduce the mass ratio of the current collector: on the one hand, by using composite metal foil films with lower density, and on the other hand, by reducing the thickness of the metal layer. Therefore, using thicker aluminum foil is not advisable at present. However, the complex process and high cost also limit the application of coating technology on composite metal foil films. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a manufacturing system for composite aluminum foil films to reduce or avoid the problems mentioned above.

[0006] To address the aforementioned technical problems, this invention proposes a manufacturing system for composite aluminum foil film, used to prepare a composite aluminum foil film composed of a substrate layer and aluminum foils adhered to both sides of the substrate layer. A rolling protective film is attached to the outer side of the aluminum foils, and the aluminum foils and the rolling protective film have uniformly distributed, correspondingly positioned holes. The manufacturing system includes at least a substrate feeding roller for conveying the substrate layer, a pair of aluminum foil feeding rollers for conveying the aluminum foils to both sides of the substrate layer, and a pair of protective film feeding rollers for conveying the rolling protective film to the outer side of the aluminum foils. At least one pair of rolling rollers are arranged on both sides of the film layer composed of the substrate layer, aluminum foils, and rolling protective film along its forward direction. Downstream of the rolling rollers is a pair of mold rollers forming the holes on both sides of the film layer, and downstream of the mold rollers is a receiving roller for the composite aluminum foil film.

[0007] Preferably, a corrosive liquid spraying mechanism for spraying corrosive liquid onto both sides of the film layer to corrode the aluminum foil in the holes, a cleaning mechanism for the sprayed film layer, a drying mechanism for the cleaned film layer, and an edge trimming mechanism for winding are further provided between the mold roller and the take-up roller.

[0008] Preferably, a pair of adhesive rollers for applying adhesive to both sides of the substrate layer are provided between the substrate feeding roller and the aluminum foil feeding roller; the metal aluminum foil is pressed and bonded to both sides of the adhesive-coated substrate layer by a pair of bonding rollers; and the rolled protective film is attached to the outside of the metal aluminum foil by a pair of attaching rollers.

[0009] Preferably, a pair of oiling rollers for applying lubricating oil to the outer side of the aluminum foil are provided between the bonding roller and the attaching roller.

[0010] Preferably, a first heating device for heating the film layer is provided between the attaching roller and the pressing roller.

[0011] Preferably, a second heating device for heating and annealing the film layer is provided between the rolling roller and the die roller.

[0012] Preferably, multiple pairs of rolling rollers with progressively increasing lengths are arranged along the forward direction of the film layer, and a set of clamping and stretching mechanisms are respectively arranged along the two sides of the film layer. The clamping and stretching mechanism includes an annular track and multiple clamping clamps that move cyclically along the annular track. The clamping clamps clamp the sides of the film layer and perform transverse clamping and stretching of the film layer along the axial direction of the rolling rollers.

[0013] Preferably, the outer surface of the mold roller is uniformly provided with a plurality of protrusions for piercing the aluminum foil and crushing the protective film to form the holes.

[0014] The manufacturing system of the present invention can be used for continuous processing of composite aluminum foil films. It can be used to prepare a low-thickness composite aluminum foil film that is rolled and stretched after lamination, avoiding the defect that it is difficult to laminate low-thickness metal aluminum foils. It can obtain thinner metal aluminum foils while ensuring conductivity and strength. Attached Figure Description

[0015] The accompanying drawings are intended only to illustrate and explain this application and do not limit the scope of this application.

[0016] Figure 1 The image shown is a cross-sectional view of a composite aluminum foil film according to a specific embodiment of the present invention.

[0017] Figure 2 The diagram shows a process structure of a composite aluminum foil film manufacturing system according to a specific embodiment of the present invention.

[0018] Figure 3 The diagram shown is a structural schematic of the rolling and stretching mechanism of a composite aluminum foil film manufacturing system according to another specific embodiment of the present invention.

[0019] Figure 4 The diagram shown is a schematic diagram of the structure of the mold roller of a composite aluminum foil manufacturing system according to yet another specific embodiment of the present invention.

[0020] Figure 5 The diagram shown is a cross-sectional schematic of the protrusions on the mold roller of a composite aluminum foil manufacturing system according to another specific embodiment of the present invention. Detailed Implementation

[0021] To provide a clearer understanding of the technical features, objectives, and effects of this application, specific embodiments are now described with reference to the accompanying drawings. Identical components are denoted by the same reference numerals.

[0022] Existing lithium batteries generally use aluminum foil obtained by rolling aluminum as the positive electrode current collector. Due to the inherent strength limitations of the material, it is difficult to reduce the thickness of the aluminum foil used, otherwise it will easily tear during operation. Even when aluminum foil is laminated with plastic film, it is impossible to use aluminum foil that is too thin for the lamination process.

[0023] In view of this, the present invention proposes a composite aluminum foil film, such as Figure 1As shown, the composite aluminum foil film consists of a substrate layer 1 and metallic aluminum foil 2 adhered to both sides of the substrate layer 1. The substrate layer 1 can be made of a plastic film made of materials such as polyolefins or polyester. In a preferred embodiment, the substrate layer 1 is preferably made of polyester film. The metallic aluminum foil 2 can be bonded to both sides of the substrate layer 1 using an adhesive (not shown in the figure), preferably a polyurethane adhesive with good high-temperature resistance.

[0024] Furthermore, the aluminum foil 2 in the composite aluminum foil film of this application is composed of a first-thickness aluminum foil of 5-15 μm, which is rolled and stretched to a second-thickness aluminum foil of 3-8 μm on both sides of the substrate layer 1. That is, the aluminum foil 2 of this application initially has a first thickness, which becomes the final second thickness after being rolled and stretched on both sides of the substrate layer 1. Since the material strength of aluminum is not very good, directly using a second-thickness aluminum foil of 3-8 μm is expensive and difficult to perform bonding and other composite operations. Therefore, this application uses a first-thickness aluminum foil of 5-15 μm as the initial raw material, which is bonded and composited with the substrate layer 1, and then rolled and stretched to become the second thickness. After that, no further composite operation is required, which can obtain a thinner aluminum foil while ensuring conductivity and strength.

[0025] For example, the aluminum foil 2 used is rolled from aluminum with an aluminum content of more than 98%, and existing finished aluminum foil products with a thickness of 5-15μm sold on the market can be selected as the initial raw material for the first thickness.

[0026] Furthermore, as shown in the figure, a rolling protective film 3 is also attached to the outer side of the aluminum foil 2 to protect the surface of the aluminum foil 2 from scratches and tears during the rolling and stretching process. The rolling protective film 3 can be made of plastic film made of materials such as polyolefin, polyester, and nylon. In a preferred embodiment, the rolling protective film 3 is preferably made of nylon film with excellent strength and self-lubricating properties, preferably with a thickness of 8-10 μm.

[0027] Furthermore, the aluminum foil 2 and the rolled protective film 3 are also uniformly distributed with corresponding holes 4. These holes 4 are evenly distributed on both sides of the composite aluminum foil film, and are all tapered holes with large openings and small ends, as shown in the figure. In a preferred embodiment, the end of the hole 4 extends into approximately half the thickness of the substrate layer 1. Of course, it is difficult to precisely extend into half the thickness of the substrate layer 1. From a cost perspective, it is preferable that the end of the hole 4 extends into 1 / 3 to 1 / 2 of the thickness of the substrate layer 1.

[0028] The holes 4 formed on the aluminum foil 2 can increase the contact area between the aluminum foil 2 and the positive electrode material, improve the adhesion between the positive electrode material and the aluminum foil 2, and prevent them from separating, thus increasing internal resistance. The holes 4 on both sides of the composite aluminum foil film shown in the figure are not through holes; this is to prevent leakage of the slurry during subsequent coating of the positive electrode material. Later, during cell compaction, these holes 4 can be enlarged by the positive electrode material, thereby increasing the contact area with the positive electrode material. In the event of a short circuit and overheating of the cell, the substrate layer 1 melts and blocks these holes 4, preventing the current from continuing to increase and reducing the risk of battery combustion and explosion.

[0029] After the aluminum foil 2 is rolled and stretched, the rolling protective film 3 still needs to be retained on the surface of the aluminum foil 2. This is to protect the aluminum foil 2 when the holes 4 are formed subsequently, so as to avoid the formation of large tear edges in the holes of the aluminum foil 2, thereby improving the consistency of the holes 4. Afterwards, the rolling protective film 3 can continue to protect the metal surface until it is necessary to remove it.

[0030] To further improve the consistency of the current collector, after forming the holes 4, a corrosive liquid can be sprayed or coated onto the surface of the rolled protective film 3 to corrode the edges of the aluminum foil 2 squeezed into the holes 4, thereby removing the edge burrs formed during the hole formation process. Simultaneously, corroding away a portion of the aluminum foil can further reduce the weight of the composite aluminum foil film, which is beneficial for improving the energy density of the lithium battery.

[0031] In a preferred embodiment, the maximum opening diameter of the hole 4 on the aluminum foil 2 is 20-30 μm, and the center distance between adjacent holes 4 is 50-100 μm.

[0032] The following reference Figure 2 The manufacturing system and preparation method of the composite aluminum foil film of this application are further described in detail. Among them, Figure 2 The diagram shows a flow chart of a manufacturing system for a composite aluminum foil film according to a specific embodiment of this application. As shown, the manufacturing system of this application is specifically designed for manufacturing... Figure 1 The composite aluminum foil film shown is the composite aluminum foil film prepared by this manufacturing system, which consists of a substrate layer 1 and metal aluminum foil 2 adhered to both sides of the substrate layer 1. A rolled protective film 3 is attached to the outer side of the metal aluminum foil 2, and holes 4 are evenly distributed on the metal aluminum foil 2 and the rolled protective film 3.

[0033] In one specific embodiment, the manufacturing system includes at least a substrate feeding roller 10 for conveying the substrate layer 1, a pair of aluminum foil feeding rollers 20 for conveying aluminum foil 2 to both sides of the substrate layer 1, and a pair of protective film feeding rollers 30 for conveying the rolled protective film 3 to the outside of the aluminum foil 2. At least a pair of rolling rollers 40 are provided on both sides of the film layer composed of the substrate layer 1, the aluminum foil 2, and the rolled protective film 3 along its forward direction. Downstream of the rolling rollers 40, a pair of mold rollers 50 are provided to form the holes 4 on both sides of the film layer. Downstream of the mold rollers 50, a take-up roller 80 for the composite aluminum foil film is provided.

[0034] In operation of the manufacturing system of this application, a substrate layer 1 can be first conveyed by the substrate feeding roller 10, for example, a substrate layer 1 made of PET is provided, the initial thickness of the substrate layer 1 being 10-20 μm. Then, a layer of aluminum foil 2 with a first thickness of 5-15 μm is conveyed to both sides of the substrate layer 1 by the aluminum foil feeding roller 20.

[0035] In one specific embodiment, a pair of adhesive rollers 11 for coating adhesive on both sides of the substrate layer 1 can also be provided between the substrate feeding roller 10 and the aluminum foil feeding roller 20; the metal aluminum foil 2 is pressed and bonded to both sides of the adhesive-coated substrate layer 1 by a pair of bonding rollers 21, thereby adhering the metal aluminum foil 2 to the substrate layer 1.

[0036] Subsequently, a rolled protective film 3, for example, a thin film of 8-10 μm thickness made of nylon, is fed to the outside of the aluminum foil 2 via a protective film feed roller 30. In the illustrated embodiment, the rolled protective film 3 can be attached to the outside of the aluminum foil 2 by a pair of attachment rollers 31.

[0037] Plastic films typically possess self-adhesive properties, allowing the rolling protective film 3 to adhere directly to the surface of the aluminum foil 2 without the need for adhesive. Alternatively, to prevent slippage, a low-tack material can be coated onto the surface of the aluminum foil 2 to facilitate subsequent removal of the rolling protective film 3. In the illustrated embodiment, a pair of oiling rollers 22 are provided between the adhesive roller 21 and the application roller 31 for applying lubricating oil to the outer side of the aluminum foil 2. Applying lubricating oil such as machine oil or silicone grease increases the adhesion of the rolling protective film 3 to the aluminum foil 2 and reduces friction during subsequent rolling and stretching, preventing film breakage.

[0038] Then, the film layer with the rolled protective film 3 attached is placed between at least one pair of rolling rollers 40, and the aluminum foil 2 is rolled from a first thickness to a second thickness of 3-8 μm by the pressure of the rolling rollers 40. Rolling the aluminum foil 2 from the first thickness to the second thickness only requires controlling the gap between the rolling rollers 40. Of course, considering the large elastic deformation capacity of the plastic in the film layer, the gap between the rolling rollers 40 is set slightly smaller than the thickness of the film layer after reduction. In addition, thinning the film layer by pure extrusion can easily damage the film layer structure. Therefore, the rolled protective film 3 in contact with the rolling rollers 40 is made of nylon to improve sliding properties and avoid extrusion. At the same time, the friction between the film layer and the rolling rollers 40 can be further reduced during rolling by applying lubricating oil. After rolling and stretching, the thickness of the substrate layer 1 changes from 10-20 μm to about 6-12 μm.

[0039] Furthermore, it is preferable to heat the film layer before it is rolled by the rolling roller 40 to increase the ductility of the plastic film and improve the efficiency of rolling and thinning. Simultaneously, the rebound of the heated plastic film is reduced, which helps maintain the thickness of the stretched film layer. In the specific embodiment shown in the figure, a first heating device 32 for heating the film layer is provided between the attaching roller 31 and the rolling roller 40. In a preferred embodiment, the first heating device 32 can use infrared heating to heat the film layer, preferably at a heating temperature of 150-170°C.

[0040] Additionally, while the film layer is being rolled by the rolling roller 40, its two sides can be laterally clamped and stretched along the axial direction of the rolling roller 40. That is, the film layer is longitudinally extended by the rolling roller 40, while simultaneously being laterally stretched by clamping the two sides in the width direction, thus accelerating the material thinning rate. Because the stretching of the aluminum foil is involved, the entire film layer needs to be clamped tightly during clamping and stretching, and the speed of lateral stretching must be controlled to avoid inconsistent stretching ratios between film layers.

[0041] Figure 3A schematic diagram of the rolling and stretching mechanism of a composite aluminum foil film manufacturing system according to another specific embodiment of this application is shown. In the illustrated embodiment, multiple pairs of rolling rollers 40 with progressively increasing lengths can be arranged along the forward direction of the film layer. A clamping and stretching mechanism 42 is arranged along each of the two sides of the film layer. The clamping and stretching mechanism 42 includes an annular track 421 and multiple clamping clamps 422 that circulate along the annular track 421. The clamping clamps 422 clamp the sides of the film layer and stretch the film layer laterally along the axial direction of the rolling rollers 40. The clamping and stretching mechanism 42 is inclined along the forward direction of the film layer. During the forward movement of the film layer, it is rolled and stretched by the multiple rolling rollers 40 at progressively wider stages, while the clamping and stretching mechanism 42 stretches both sides progressively. The clamping clamps 422 can be configured to automatically close to clamp the sides when they move along the annular track 421 to a position where they meet the sides of the film layer, and automatically open to release the sides when they move along the annular track 421 to a position where they separate from the sides of the film layer.

[0042] Next, the rolled film layer is placed between a pair of die rollers 50 with protrusions 51. The protrusions 51 on the die rollers 50 uniformly form corresponding holes 4 on the aluminum foil 2 and the rolled protective film 3, such as... Figure 4 As shown in the illustration. In a specific embodiment, the outer surface of the mold roller 50 is uniformly provided with a plurality of protrusions 51 for piercing the aluminum foil 2 and the protective film 3 to form the holes 4. In another specific embodiment, the protrusions 51 are cones, the bottom diameter D of the cones is 20-30 μm, and the center distance between adjacent cones is 50-100 μm, as shown. Figure 5 As shown. Through the uniformly arranged protrusions 51 on the mold roller 50, holes 4 of the required size and position can be formed on the film layer, which can ensure the uniformity of the film layer structure.

[0043] If stress exists during the rolling of the membrane layer when forming the holes 4, the excessively stressed membrane layer will displace and shrink after perforation, causing the holes to close when the protrusions are removed. To avoid this problem, it is preferable to heat-anneal the membrane layer before forming the holes 4 to minimize stress in the membrane layer. Figure 2 In the specific embodiment shown, a second heating device 41 for heating and annealing the film layer can also be provided between the rolling roller 40 and the die roller 50. The preferred annealing temperature is 130-150°C, and the annealing time is 5-15 minutes.

[0044] After annealing to release stress, if there is still a small amount of stress concentration, this stress can be released by puncturing to form holes 4, thus preventing the composite aluminum foil film from becoming twisted and uneven. Although a small amount of stress may cause the holes 4 to deform, by setting the appropriate hole size and center distance as described above, the holes can be prevented from closing completely.

[0045] Furthermore, after forming the holes 4, a corrosive liquid can be sprayed or coated onto the surface of the rolling protective film 3 to corrode the edges of the aluminum foil 2 extruded into the holes 4, thereby removing the edge burrs formed during hole formation. Finally, the film is rinsed with water to remove the corrosive liquid, then dried, trimmed, and wound up. In the specific embodiment shown in the figure, a corrosive liquid spraying mechanism 60 for spraying corrosive liquid onto both sides of the film layer to corrode the aluminum foil in the holes 4, a cleaning mechanism 61 for the sprayed film layer, a drying mechanism 70 for the cleaned film layer, and a trimming mechanism 71 for winding up can be further provided between the die roller 50 and the take-up roller 80.

[0046] Furthermore, in the manufacturing system of this application, where the oiling roller 22 is provided, a protective film receiving roller (not shown in the figure) for removing the rolled protective film 3 can also be provided between the corrosive liquid spraying mechanism 60 and the cleaning mechanism 61. That is, after spraying and corrosion, the rolled protective film 3 can be removed, along with most of the corrosive liquid, and the lubricating oil coated on the aluminum foil 2 is exposed. The lubricating oil can also be removed during cleaning. At this time, the cleaning mechanism 61 can have multiple cleaning heads, which can first remove oil, then remove acid, and finally rinse with clean water.

[0047] Those skilled in the art should understand that although this application is described by way of multiple embodiments, not every embodiment contains only one independent technical solution. This description is merely for clarity, and those skilled in the art should understand the specification as a whole and consider the technical solutions involved in each embodiment as being able to be combined with each other to form different embodiments to understand the scope of protection of this application.

[0048] The above description is merely an illustrative embodiment of this application and is not intended to limit the scope of this application. Any equivalent changes, modifications, and combinations made by those skilled in the art without departing from the concept and principles of this application shall fall within the scope of protection of this application.

Claims

1. A manufacturing system for composite aluminum foil film, used to prepare a composite aluminum foil film consisting of a substrate layer (1) and metal aluminum foil (2) adhered to both sides of the substrate layer (1), wherein a rolling protective film (3) is attached to the outer side of the metal aluminum foil (2), and the metal aluminum foil (2) and the rolling protective film (3) have uniformly distributed corresponding holes (4); characterized in that, The manufacturing system includes at least a substrate feeding roller (10) for conveying the substrate layer (1), a pair of aluminum foil feeding rollers (20) for conveying aluminum foil (2) to both sides of the substrate layer (1), and a pair of protective film feeding rollers (30) for conveying a rolled protective film (3) to the outside of the aluminum foil (2). At least one pair of rolling rollers (40) are provided on both sides of the film layer composed of the substrate layer (1), aluminum foil (2), and rolled protective film (3) along its forward direction. Downstream of the rolling rollers (40) is a pair of mold rollers (50) for forming the holes (4) on both sides of the film layer. Downstream of the mold rollers (50) is a receiving roller (80) for the composite aluminum foil film. Further between the mold rollers (50) and the receiving rollers (80) is a corrosive liquid spraying mechanism (60) for spraying a corrosive liquid onto both sides of the film layer to corrode the aluminum foil in the holes (4), and a spraying mechanism for spraying the corrosive liquid. The system includes a film cleaning mechanism (61), a film drying mechanism (70) for the cleaned film, and a trimming mechanism (71) for winding. A pair of adhesive rollers (11) for applying adhesive to both sides of the substrate layer (1) are provided between the substrate feeding roller (10) and the aluminum foil feeding roller (20). The metal aluminum foil (2) is pressed and bonded to both sides of the adhesive-coated substrate layer (1) by a pair of bonding rollers (21). The rolling protective film (3) is attached to the outside of the metal aluminum foil (2) by a pair of attaching rollers (31). A pair of oiling rollers (22) for applying lubricating oil to the outside of the metal aluminum foil (2) are provided between the bonding roller (21) and the attaching roller (31). A first heating device (32) for heating the film is provided between the attaching roller (31) and the rolling roller (40). A second heating device (41) for heating and annealing the film is provided between the rolling roller (40) and the die roller (50).

2. The manufacturing system as described in claim 1, characterized in that, Multiple pairs of rolling rollers (40) with progressively increasing lengths are arranged along the forward direction of the film layer. A set of clamping and stretching mechanisms (42) is arranged along the two sides of the film layer. The clamping and stretching mechanism (42) includes an annular track (421) and multiple clamping clamps (422) that move cyclically along the annular track (421). The clamping clamps (422) clamp the sides of the film layer and stretch the film layer laterally along the axial direction of the rolling rollers (40).

3. The manufacturing system as described in any one of claims 1-2, characterized in that, The outer surface of the mold roller (50) is uniformly provided with a plurality of protrusions (51) for piercing the aluminum foil (2) and rolling the protective film (3) to form the hole (4).

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