Composite aluminum foil, manufacturing method of composite aluminum foil and battery

Abstract

The invention discloses a composite aluminum foil, a manufacturing method of the composite aluminum foil and a battery. The composite aluminum foil comprises a first aluminum layer, a resin layer and a second aluminum layer which are sequentially stacked, porous layers are formed on the sides, facing the resin layer, of the first aluminum layer and the second aluminum layer, each porous layer comprises a plurality of micropores, and at least part of the resin layer is fixedly connected into the micropores. According to the technical scheme, the porous layers are arranged on the sides, facing the resin layers, of the first aluminum layer and the second aluminum layer of the composite aluminum foil, each porous layer is composed of the multiple micropores distributed at intervals, and when the resin layers are fixedly connected with the surfaces of the first aluminum layer and the second aluminum layer, part of the resin layers stretch into the micropores and are fixedly connected with the micropores, so that the service life of the composite aluminum foil is prolonged. The contact area between the resin layer and the first aluminum layer and the second aluminum layer is increased, the bonding capacity between the resin layer and the first aluminum layer and the second aluminum layer is improved, and then the stability of connection between the resin layer and the first aluminum layer and the second aluminum layer is improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a composite aluminum foil, a method for manufacturing the composite aluminum foil, and a battery. Background Art

[0002] As one of the commonly used materials for battery electrodes, composite aluminum foil is widely favored by battery manufacturers due to its low resistance and high conductivity. There are usually two mainstream manufacturing methods for composite aluminum foil. One is to use vacuum coating to bombard the surface of the substrate with aluminum atoms, and then deposit aluminum layers on the opposite sides of the substrate, and finally form a composite aluminum foil with an aluminum layer-substrate layer-aluminum layer structure. The other is to use hot pressing composite technology to use adhesives to bond the aluminum layer to the surface of the substrate layer, and finally form a composite aluminum foil with the above structure.

[0003] However, for the first manufacturing method, due to the high price of the target material for vacuum coating, the high power consumption and long production time of the production process, the cost of the composite aluminum foil produced by this production method is much higher than that of pure aluminum foil, and it does not have a competitive advantage. At the same time, since the temperature of the aluminum particles bombarding the substrate is extremely difficult to control, once the temperature of the coated particles bombarding the substrate exceeds the melting point of the substrate itself, it will cause damage to the substrate. Therefore, the composite aluminum foil produced by this method has an extremely low yield rate. For the second manufacturing method, in order to achieve a good bonding effect, the thickness of the bonding layer of the single-sided aluminum foil usually needs to reach 1-3μm, plus the original thickness of the substrate layer, the thickness of the bonding layer and the resin layer of the composite aluminum foil finally produced usually reaches 5μm-11μm, which seriously affects the current collecting effect of the current collector made of the composite aluminum foil.

[0004] Based on this, how to optimize the structure of composite aluminum foil, reduce the manufacturing cost of aluminum foil, and improve the manufacturing yield of aluminum foil has become an urgent problem to be solved. Summary of the invention

[0005] The purpose of the present application is to provide a composite aluminum foil, a method for manufacturing the composite aluminum foil, and a battery, aiming to solve the problems of high manufacturing cost and low yield rate of the existing composite aluminum foil.

[0006] To achieve the purpose of the present application, in a first aspect, the present application provides a composite aluminum foil, comprising a first aluminum layer, a resin layer, and a second aluminum layer stacked in sequence;

[0007] A porous layer is formed on the first aluminum layer and the second aluminum layer facing the resin layer. The porous layer includes a plurality of micropores. The resin layer is at least partially fixedly connected in the micropores.

[0008] In the technical solution of the present application, a porous layer is provided on the side of the first aluminum layer and the second aluminum layer of the composite aluminum foil facing the resin layer, and the porous layer is composed of a plurality of micropores. While the resin layer is fixedly connected to the surface of the first aluminum layer and the second aluminum layer, part of the resin layer extends into the micropores and is fixedly connected to the micropores, so that the contact area between the resin layer and the first aluminum layer and the second aluminum layer is increased, and the bonding ability between the resin layer and the first aluminum layer and the second aluminum layer is improved, thereby improving the connection stability between the resin layer and the first aluminum layer and between the resin layer and the second aluminum layer. The improvement of the bonding ability between the resin layer and the first aluminum layer and between the resin layer and the second aluminum layer reduces the bonding difficulty between the resin layer and the first aluminum layer and between the resin layer and the second aluminum layer, reduces the bonding process requirements between the resin layer and the first aluminum layer and between the resin layer and the second aluminum layer, reduces the manufacturing cost of the composite aluminum foil, and improves the yield of the composite aluminum foil. At the same time, since there is no need to add an adhesive layer between the resin layer and the first aluminum layer and between the resin layer and the second aluminum layer, the composite aluminum foil of this structure is thinner.

[0009] In a possible implementation manner, a plurality of inner connection holes are formed on the inner wall surface of the micropore, and the resin layer is fixedly connected in the inner connection holes.

[0010] In a possible implementation, the thickness of the porous layer is A, 0.1 μm≤A≤6 μm; and / or,

[0011] The pore size of the micropore is B, 0.2 μm≤B≤2 μm; and / or,

[0012] The density of the micropores distributed in the porous layer is C, 50EA. / mm 2 ≤C≤5000EA. / mm 2 and / or,

[0013] The diameter of the inner connection hole is D, 10nm≤D≤100nm.

[0014] In a possible implementation, the melting point of the resin used in the resin layer is E, 100°C≤E≤150°C.

[0015] In a possible implementation, the resin used in the resin layer includes: polypropylene and polyethylene, the weight of polypropylene is F, the weight of polyethylene is G, F:G=X:1, wherein 1≤X≤3.

[0016] In a possible implementation, the thickness of the first aluminum layer is L1, 1 μm≤L1≤8 μm;

[0017] The thickness of the second aluminum layer is L2, 1 μm≤L2≤8 μm.

[0018] In a possible implementation, the thickness of the resin layer is L3, 0.5 μm≤L3≤8 μm.

[0019] In a possible implementation, the thickness of the resin layer is L3, 1 μm≤L3≤3 μm.

[0020] In a second aspect, the present application also proposes a method for manufacturing a composite aluminum foil, comprising the following steps:

[0021] The first aluminum foil is surface-treated to form a first aluminum layer, and the second aluminum foil is surface-treated to form a second aluminum layer, wherein a porous layer is formed on one side of the first aluminum layer and a porous layer is formed on one side of the second aluminum layer, and each of the porous layers includes a plurality of micropores;

[0022] The first aluminum layer, the resin layer, and the second aluminum layer are stacked in sequence to form the composite aluminum foil, the porous layer of the first aluminum layer and the porous layer of the second aluminum layer are both arranged toward the resin layer, and at least a portion of the resin layer is fixedly connected to the plurality of micropores.

[0023] In a possible implementation, the surface treatment of the first aluminum foil and the surface treatment of the second aluminum foil include the following steps:

[0024] Covering one side of the first aluminum foil with a protective film to form a first single-sided coated aluminum foil;

[0025] Covering one side of the second aluminum foil with a protective film to form a second single-sided coated aluminum foil;

[0026] The first single-sided coated aluminum foil and the second single-sided coated aluminum foil are placed in concentrated sulfuric acid for electrolysis to form the first aluminum layer and the second aluminum layer, and a porous layer is formed on one side of the first aluminum layer and the second aluminum layer, and the porous layer includes a plurality of micropores, and the inner wall surface of the micropores is formed with a plurality of internal connecting holes.

[0027] In a possible implementation, after the first single-sided film-coated aluminum foil and the second single-sided film-coated aluminum foil are placed in concentrated sulfuric acid for electrolysis, the following steps are further included:

[0028] The porous layers of the first aluminum layer and the second aluminum layer are etched using an etching solution.

[0029] In a possible implementation, the electrolysis voltage of the electrolysis treatment is V, 6v≤V≤20v; and / or,

[0030] The electrolysis temperature of the electrolysis treatment is T, 20°C ≤ T ≤ 30°C; and / or,

[0031] The electrolysis time of the electrolysis treatment is t, 10s≤t≤12000s; and / or,

[0032] The mass fraction of the concentrated sulfuric acid is n, 10%≤n≤25%.

[0033] The composite aluminum foil manufacturing method of the present invention is simple and low in cost. The composite aluminum foil prepared by the method has a thin thickness.

[0034] In a third aspect, the present application further provides a battery, the battery comprising a composite aluminum foil, the composite aluminum foil comprising: a first aluminum layer, a resin layer, and a second aluminum layer stacked in sequence;

[0035] A porous layer is formed on the first aluminum layer and the second aluminum layer facing the resin layer. The porous layer includes a plurality of micropores. The resin layer is at least partially fixedly connected in the plurality of micropores. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 A cross-sectional view of an embodiment of the composite aluminum foil provided in the present application;

[0038] Figure 2 for Figure 1 Partial view at A;

[0039] Figure 3 A schematic flow chart of a first embodiment of a method for manufacturing a composite aluminum foil provided in the present application;

[0040] Figure 4 A schematic flow chart of a second embodiment of the method for manufacturing a composite aluminum foil provided in the present application;

[0041] Figure 5 This is a schematic diagram of the structure of the resin layer coating device.

[0042] Description of reference numerals:

[0043] 1000 composite aluminum foil;

[0044] 1 resin layer;

[0045] 2 First aluminum layer;

[0046] 3. Second aluminum layer;

[0047] 4 porous layer, 41 micropores, 42 internal connection holes;

[0048] 2000 Extruder;

[0049] 3000 First Unwinder;

[0050] 4000 2nd unwinder;

[0051] 5000 Winder;

[0052] 6000 cooling roller set;

[0053] 7000 molten resin. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0055] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there can be a central component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there can be a central component at the same time.

[0056] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in this application and in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this application includes any and all combinations of one or more of the related listed items.

[0057] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0058] The existing composite aluminum foil manufacturing method has high cost and low yield. To solve this problem, please refer to Figure 1 and Figure 2 The present application provides a battery, the battery includes an electrode, the current collector of the electrode includes a composite aluminum foil 1000, the composite aluminum foil 1000 includes a first aluminum layer 2, a resin layer 1 and a second aluminum layer 3 stacked in sequence; the first aluminum layer 2 and the second aluminum layer 3 are formed with a porous layer 4 on the side facing the resin layer 1, the porous layer 4 includes a plurality of micropores 41, and the resin layer 1 is at least partially fixedly connected in the micropores 41.

[0059] In the technical solution of the present application, a porous layer 4 is provided on the side of the first aluminum layer 2 of the composite aluminum foil 1000 facing the resin layer 1 and the side of the second aluminum layer 3 facing the resin layer 1. The porous layer 4 is composed of a plurality of micropores 41. While the resin layer 1 is fixedly connected to the surface of the first aluminum layer 2 and the surface of the second aluminum layer 3, part of the resin layer 1 extends into the micropores 41 and is fixedly connected to the micropores 41. In this way, the contact area between the resin layer 1 and the first aluminum layer 2 and the second aluminum layer 3 is increased, and the bonding ability between the resin layer 1 and the first aluminum layer 2 and the second aluminum layer 3 is improved, thereby improving the stability of the connection between the resin layer 1 and the first aluminum layer 2 and the second aluminum layer 3. At the same time, the improvement of the bonding ability between the resin layer 1 and the first aluminum layer 2 and the second aluminum layer 3 also reduces the bonding difficulty between the resin layer 1 and the first aluminum layer 2 and the second aluminum layer 3. The reduction in the difficulty of combining the resin layer 1 and the first aluminum layer 2, and the resin layer 1 and the second aluminum layer 3, on the one hand, reduces the requirements of the composite aluminum foil 1000 for the material properties of the resin layer 1, so that more resins are included in the range of options for the resin layer 1. On the other hand, it also reduces the requirements for the process of combining the resin layer 1 and the first aluminum layer 2, and the resin layer 1 and the second aluminum layer 3, and more process methods with lower costs and higher yields are included in the range of options for the connection process of the resin layer 1 and the first aluminum layer 2 and the second aluminum layer 3, which reduces the manufacturing cost of the composite aluminum foil 1000 and improves the yield of the product. At the same time, since there is no need to add an adhesive layer between the resin layer 1 and the first aluminum layer 2, and between the resin layer 1 and the second aluminum layer 3, the composite aluminum foil 1000 under this structure is thinner.

[0060] The resin layer 1 is the middle layer of the composite aluminum foil 1000, and its function is to serve as a carrier for the aluminum layers on both sides. The purpose of using resin as a material is to reduce the weight of the composite aluminum foil 1000 after manufacture, and at the same time improve the toughness of the composite aluminum foil 1000. Generally speaking, in order to improve the bearing capacity of the resin layer 1 and at the same time improve the strength of the composite aluminum foil 1000, the thickness L3 of the resin layer 1 is generally in the range of 0.5μm-8μm. In one embodiment of the present application, the thickness L3 of the resin layer 1 is preferably 1μm-3μm, so as to reduce the thickness of the resin layer 1 and reduce the weight of the resin layer 1, thereby reducing the mass of the composite aluminum foil 1000 and reducing the thickness of the composite aluminum foil 1000 while ensuring the strength and toughness of the composite aluminum foil 1000. It should be noted that the thickness of the resin layer 1 referred to above refers to the thickness of the resin material located between the two porous layers 4.

[0061] The material selection range of the resin layer 1 is very wide. The resin layer 1 can be made of a single resin or a mixed resin, and this application does not limit this. In one embodiment of the present application, the melting point of the material of the resin layer 1 is E, 100°C ≤ E ≤ 150°C. When the circuit connected to the composite aluminum foil 1000 has thermal runaway due to a short circuit, the resin layer 1 can melt and deform under the high temperature of the short circuit, thereby causing the two ends of the current collector to shrink and deform toward the middle, thereby disconnecting the circuit at both ends of the current collector to protect the circuit safety.

[0062] There are many resin materials based on the above melting point requirements. The resin layer 1 can be polyethylene (PE), polystyrene (PS), polypropylene (PP) or other plastic particles with a melting point of 100-150°C that are added with reinforcing materials or manufactured by special processes. This application does not limit this. In another embodiment of the present application, the resin layer 1 is made of a mixture of polypropylene and polyethylene, the weight of polypropylene is F, the weight of polyethylene is G, F: G = X: 1, wherein 1≤X≤3, in this embodiment, the melting point of polyethylene is about 110°C, and the melting point of polypropylene is about 150°C. Since the melting points of polyethylene and polypropylene are quite different, when the circuit is thermally runaway, the polyethylene with a lower melting point begins to melt, so that the collector is disconnected from the circuit and the short circuit is eliminated. When the short circuit is eliminated, the circuit temperature drops, and the polypropylene with a higher melting point has not yet melted and remains in its original state. In this way, it can be ensured that when a short circuit occurs in the circuit, it melts quickly to eliminate the short circuit, and the overall structure of the resin layer 1 is kept from changing too much, so that the heat accumulated at the composite aluminum foil 1000 is easily dissipated.

[0063] The first aluminum layer 2 and the second aluminum layer 3 are respectively compounded on the opposite two sides of the resin layer 1. The first aluminum layer 2 and the second aluminum layer 3 are used to provide conditions for the conduction of electrons. The first aluminum layer 2 and the second aluminum layer 3 can both use double-sided reflective aluminum foil or single-sided reflective aluminum foil, and this application does not limit this. Further, for the composite aluminum foil 1000, the thickness L1 of the first aluminum layer 2 and the second aluminum layer 3 is preferably 1-2 μm. The thickness of the first aluminum layer 2 and the second aluminum layer 3 within the above range can further improve the ability of the first aluminum layer 2 and the second aluminum layer 3 to conduct electrons while reducing the weight of the composite aluminum foil 1000. Therefore, in one embodiment of the present application, the first aluminum layer 2 and the second aluminum layer 3 can both use single-sided light aluminum foil with a thickness of 6 μm-8 μm as raw materials. After the aluminum foil is corroded by chemical agents, the first aluminum layer 2 and the second aluminum layer 3 with a thickness between 1 μm and 8 μm are finally formed. In this way, under the premise of satisfying the circuit conduction, the weight of the first aluminum layer 2 and the second aluminum layer 3 is reduced, thereby reducing the weight of the composite aluminum foil 1000 after forming.

[0064] A porous layer 4 is provided on the side of the first aluminum layer 2 and the second aluminum layer 3 facing the resin layer 1, and micropores 41 are distributed in the porous layer 4. The micropores 41 are used to increase the contact area between the resin layer 1 and the first aluminum layer 2, and between the resin layer 1 and the second aluminum layer 3, and improve the stability of the connection between the resin layer 1 and the first aluminum layer 2, and between the resin layer 1 and the second aluminum layer 3. Furthermore, in one embodiment of the present application, the thickness of the porous layer 4 is A, the pore size of the micropores 41 is B, and the pore density of the micropores 41 distributed in the porous layer 4 is C. When one of the following conditions is met: (1) 0.1μm≤A≤6μm, (2) 0.2μm≤B≤2μm, (3) 50EA. / mm2≤C≤5000EA. / mm2, the stability of the connection between the first aluminum layer 2 and the second aluminum layer 3 and the resin layer 1 can be more effectively improved.

[0065] It should be explained that when the porous layer is disposed between the first aluminum layer and the resin layer, the thickness of the porous layer refers to the farthest distance from the micropores in the porous layer to the interface of the first aluminum layer, the resin layer and the second aluminum layer in the stacking direction. When the porous layer is disposed between the second aluminum layer and the resin layer, the thickness of the porous layer refers to the farthest distance from the micropores in the porous layer to the interface of the second aluminum layer and the resin layer in the stacking direction. In the actual production process, the farthest distance referred to above is generally related to the depth of the micropores. The farthest distance is generally the maximum depth of the micropores. The micropore depth test method is as follows:

[0066] 1. Use focused ion beam (FIB) to microcut the micropores so that the cross-sectional morphology of the micropores can be revealed.

[0067] 2. Scan the cross section of the micropores using a scanning electron microscope (SEM), and measure the scanned cross section to ultimately obtain the depth of the micropores.

[0068] The distribution density of micropores in the porous layer refers to the proportion of the number of micropores in the unit area. The density test method is as follows:

[0069] For micropores with a pore size of more than 1 micron, use an optical microscope to observe the sample surface or cross-section, count the number of tiny pores per unit area or volume, and thus obtain the density of the tiny pores.

[0070] Micropores with a pore size of less than 1 micron are observed using a scanning electron microscope (SEM): The sample surface is observed using an SEM, and its high resolution can show the shape and distribution of tiny pores. The density of tiny pores can be obtained by image processing and calculation on the SEM image.

[0071] The superposition of the two results is the pore density of the sample.

[0072] Please refer to Figure 2 In order to further improve the stability of the connection between the resin layer 1 and the first aluminum layer 2, and between the resin layer 1 and the second aluminum layer 3, in another embodiment of the present application, a plurality of internal connection holes 42 are formed on the inner wall surface of the hole, and the resin layer 1 is fixedly connected to the internal connection holes 42, so as to further increase the contact area between the resin layer 1 and the aluminum layer, and improve the stability of the connection between the resin layer 1 and the first aluminum layer 2 and the second aluminum layer 3. In another embodiment of the present application, the aperture of the internal connection hole 42 is D, and when 10nm≤D≤100nm, it can not only further ensure that the resin layer 1 easily enters the internal connection hole 42, increase the contact area between the resin layer 1 and the internal connection hole 42, but also improve the stability of the connection between the resin layer 1 and the internal connection hole 42.

[0073] The aperture of the internal connection hole can also be measured by FIB method. The specific steps include:

[0074] 1. Use focused ion beam (FIB) to microcut the micropores so that the cross-sectional morphology of the micropores can be revealed.

[0075] 2. Scan the cross section of the internal connection hole using a scanning electron microscope (SEM), and measure the scanned cross section to finally obtain the aperture size of the internal connection hole.

[0076] This application also provides a method for manufacturing a composite aluminum foil, please refer to Figure 3 , Figure 3 This is a schematic flow chart of a first embodiment of a method for manufacturing a composite aluminum foil provided in the present application. The method for manufacturing a composite aluminum foil comprises the following steps:

[0077] S101, performing surface treatment on a first aluminum foil to form a first aluminum layer, performing surface treatment on a second aluminum foil to form a second aluminum layer, wherein a porous layer is formed on one side of the first aluminum layer and one side of the second aluminum layer, and each of the porous layers includes a plurality of micropores.

[0078] There are many ways to form a porous layer on the surface of the first aluminum foil and the second aluminum foil. The porous layer can be formed on one side of the first aluminum foil and the second aluminum foil by anodizing, or by metal and plastic nano-mold forming technology (NMT) to form a porous layer on one side of the first aluminum foil and the second aluminum foil. This application does not impose any restrictions on this.

[0079] S102, stacking the first aluminum layer, the resin layer, and the second aluminum layer in sequence to form the composite aluminum foil, wherein the porous layer of the first aluminum layer and the porous layer of the second aluminum layer are both arranged toward the resin layer, and at least a portion of the resin layer is fixedly connected to the plurality of micropores.

[0080] There are many ways to laminate the first aluminum layer, the second aluminum layer and the resin layer in sequence. The resin layer can be laminated with the first aluminum layer and the second aluminum layer by hot pressing, or by injection molding, and the present application does not impose any restrictions on this.

[0081] The manufacturing method of the composite aluminum foil provided in the present application reduces the manufacturing cost of the composite aluminum foil and improves the manufacturing yield rate of the composite aluminum foil. At the same time, since the manufacturing method eliminates the adhesive layer, the composite aluminum foil manufactured by the method is thinner, lighter and has better conductive effect.

[0082] Please refer to Figure 4 , Figure 4 This is a schematic flow chart of a second embodiment of the method for manufacturing a composite aluminum foil provided in the present application. In this embodiment, the method for manufacturing a composite aluminum foil includes the following steps:

[0083] S201, covering one side of the first aluminum foil with a protective film to form a first single-sided coated aluminum foil.

[0084] S202, covering one side of the second aluminum foil with a protective film to form a second single-sided coated aluminum foil.

[0085] The protective film is used to protect the side of the first aluminum foil and the second aluminum foil that does not participate in the reaction, so as to prevent the aluminum foil surface on this side from reacting with the solution.

[0086] S203, placing the first single-sided coated aluminum foil and the second single-sided coated aluminum foil in concentrated sulfuric acid for electrolytic treatment to form the first aluminum layer and the second aluminum layer, wherein a porous layer is formed on one side of the first aluminum layer and the second aluminum layer, and the porous layer includes a plurality of micropores, and the inner wall surface of the micropores is formed with a plurality of internal connecting holes.

[0087] In order to form a porous layer on the surface of the aluminum foil, the surface treatment of the aluminum foil can be anodizing, or metal and plastic nano-mold forming technology can be used. Considering that the metal and plastic nano-mold forming technology can only generate micropores on the surface of the aluminum foil, but cannot continue to produce internal connecting holes in the micropores, therefore, in this embodiment, anodizing is selected to perform surface treatment on the first aluminum foil and the second aluminum foil.

[0088] Specifically, the micropores 41 and the inner connection holes 42 that meet the requirements can be generated on the surface of the aluminum foil by adjusting the conditions of the electrolytic treatment. In the above embodiment, the first voltage is V, the first electrolytic temperature is T, the first preset time is t, and the mass fraction of concentrated sulfuric acid is n. One way is to control the conditions of the electrolytic treatment to 6v≤V≤20v, 20℃≤T≤30℃, 10s≤t≤12000s, 10%≤n≤25%. Electrolytic treatment within the above conditions can form the micropores 41 and the inner connection holes 42 that meet the requirements on the surface of the aluminum foil. Further, in this embodiment, V=11V, T=25℃, t=350s, n=15%, so as to form a porous layer 4 with a thickness of 0.1-6μm, a pore size of 0.2-2um, and a pore density of 50-5000EA. / mm2 on one side of the first aluminum layer 2 and the second aluminum layer 3.

[0089] S204, etching the porous layers of the first aluminum layer and the second aluminum layer using an etching solution.

[0090] Acidic or alkaline etching solutions can be used. Acidic etching solutions include various acidic solutions, such as hydrochloric acid (HCl), nitric acid (HNO3) and sulfuric acid (H2SO4). These acidic etching solutions can effectively corrode aluminum, and the etching rate and surface characteristics can be adjusted according to different parameters such as different acid concentrations and temperatures. Commonly used ingredients of alkaline etching solutions are sodium hydroxide (NaOH) or ammonium hydroxide (NH4OH). According to the control of solution concentration and temperature, the etching rate and surface morphology can be adjusted. There are two main purposes for using etching solutions. On the one hand, the etching solution can increase the pore size and depth of the micropores and internal connecting holes in the porous layer, thereby increasing the contact area between the resin layer and the first aluminum layer and the resin layer and the second aluminum layer, and improving the stability of the connection between the resin layer and the first aluminum layer and the resin layer and the second aluminum layer. On the other hand, the etching solution can further coarsen the surface of the porous layer, thereby increasing the adsorption of the porous layer to the resin layer, and thereby improving the stability of the connection between the resin layer and the first aluminum layer and the resin layer and the second aluminum layer.

[0091] S205. Stack the first aluminum layer, the resin layer, and the second aluminum layer in sequence to form the composite aluminum foil, wherein the porous layer of the first aluminum layer and the porous layer of the second aluminum layer are both arranged toward the resin layer, and at least a portion of the resin layer is fixedly connected to the plurality of micropores.

[0092] There are many ways to stack the first aluminum layer, the second aluminum layer and the resin layer in sequence. In this embodiment, the first aluminum layer and the second aluminum layer are integrally formed with the resin layer by injection molding through a laminating process. For details, please refer to Figure 5 , Figure 5The figure is a simplified structural diagram of a resin layer 1 coating device, which includes an extruder 2000, a first unwinder 3000, a second unwinder 4000, a reel 5000 and a cooling roller group 6000. The first unwinder 3000 is used to wind the first aluminum layer 2, the second unwinder 4000 is used to wind the second aluminum layer 3, the extruder 2000 is used to spray molten resin 7000 downwards, the reel 5000 is used to reel the composite aluminum foil 1000, and cooperate with the first unwinder 3000 and the second unwinder 4000 to drive the first aluminum layer 2 and the second aluminum layer 3 to move, the cooling roller group 6000 is used to cool the molten resin 7000, and press the first aluminum layer 2, the molten resin 7000 and the second aluminum layer 3 together. In the actual operation process, the first unwinder 3000, the second unwinder 4000 and the second aluminum layer 3 are pressed together. 000 moves, and drives the first aluminum layer 2 and the second aluminum layer 3 to move. When the first aluminum layer 2 and the second aluminum layer 3 move to the cooling roller group 6000, the extruder 2000 sprays the molten resin 7000 downwardly, so that the molten resin 7000 is in contact with the first aluminum layer 2 and the second aluminum layer 3 at the cooling roller resistance. The molten resin 7000 after contacting the first aluminum layer 2 and the second aluminum layer 3 quickly penetrates into the micropores 41 and the internal connecting holes 42 of the first aluminum layer 2 and the second aluminum layer 3 under the action of the cooling roller group 6000, and is quickly cooled, and then is fixedly connected with the first aluminum layer 2 and the second aluminum layer 3, so as to finally form a composite aluminum foil 1000. The composite aluminum foil 1000 is wound under the action of the winder 5000, and drives the first aluminum layer 2 and the second aluminum layer 3 to continue to move toward the cooling roller group 6000.

[0093] Furthermore, in this embodiment, the resin layer 1 is made of polypropylene and polyethylene, and the weight ratio of polypropylene to polyethylene is 1:1. The unwinding speed of the first unwinding machine 3000 and the second unwinding machine 4000 is H, H=20m / min.

[0094] The technical solution of the present invention is described in detail below through specific embodiments.

[0095] Example 1

[0096] 1. Cover one side of the first aluminum foil with a protective film to form a first single-sided coated aluminum foil with a thickness of 6 μm.

[0097] 2. Cover one side of the second aluminum foil with a protective film to form a second single-sided coated aluminum foil with a thickness of 6 μm.

[0098] 3. Using anodizing technology, the first single-sided coated aluminum foil and the second single-sided coated aluminum foil are placed as anodes in a 15% sulfuric acid solution, the voltage is 11V, the reaction temperature is 25°C, and the electrolysis is performed for 350s to obtain a porous layer with a thickness of 0.5μm, a pore size of 0.3um, and a pore density of 2000EA. / mm2. The pore size of the internal connection pores is between 10-100nm. The thickness of the first aluminum layer and the second aluminum layer is 3μm.

[0099] 4. Heat a mixture of polypropylene (PP) and polyethylene (PE) in a mass ratio of 1:1 to a molten state.

[0100] 5. Using the laminating process described above, a mixed material of polypropylene (PP) and polyethylene (PE) is laminated onto the porous layer of the first aluminum foil and the porous layer of the second aluminum layer; wherein the unwinding speed of the first unwinder and the second unwinder is 20 m / min. The thickness of the resin layer is 3 μm.

[0101] Example 2

[0102] 1. Cover one side of the first aluminum foil with a protective film to form a first single-sided coated aluminum foil with a thickness of 8 μm.

[0103] 2. Cover one side of the second aluminum foil with a protective film to form a second single-sided coated aluminum foil with a thickness of 8 μm.

[0104] 3. Using anodizing technology, the first single-sided coated aluminum foil and the second single-sided coated aluminum foil were placed as anodes in a 15% sulfuric acid solution, and the voltage was 30V, and the reaction temperature was 25°C for electrolysis for 350s to obtain a porous layer with a thickness of 0.5μm, a pore size of 0.3um, and a pore density of 2000EA. / mm2, but no internal connection holes. The thickness of the first aluminum layer and the second aluminum layer is 3μm.

[0105] 4. Heat a mixture of polypropylene (PP) and polyethylene (PE) in a mass ratio of 1:1 to a molten state.

[0106] 5. Using the laminating process described above, a mixed material of polypropylene (PP) and polyethylene (PE) is laminated onto the porous layer of the first aluminum foil and the porous layer of the second aluminum layer; wherein the unwinding speed of the first unwinder and the second unwinder is 20 m / min. The thickness of the resin layer is 3 μm.

[0107] Example 3

[0108] 1. Cover one side of the first aluminum foil with a protective film to form a first single-sided coated aluminum foil with a thickness of 6 μm.

[0109] 2. Cover one side of the second aluminum foil with a protective film to form a second single-sided coated aluminum foil with a thickness of 6 μm.

[0110] 3. Using anodizing technology, the first single-sided coated aluminum foil and the second single-sided coated aluminum foil were placed as anodes in a sulfuric acid solution with a mass fraction of 18%, and the voltage was 10V, and the reaction temperature was 25°C for 400s to obtain a porous layer with a thickness of 0.6μm, a pore size of 0.4um, and a pore density of 3000EA. / mm2. The pore size of the internal connection pores was between 10-100nm. The thickness of the first aluminum layer and the second aluminum layer was 3μm.

[0111] 4. Heat a mixture of polypropylene (PP) and polyethylene (PE) in a mass ratio of 1:1 to a molten state.

[0112] 5. Using the laminating process described above, a mixed material of polypropylene (PP) and polyethylene (PE) is laminated onto the porous layer of the first aluminum foil and the porous layer of the second aluminum layer; wherein the unwinding speed of the first unwinder and the second unwinder is 20 m / min. The thickness of the resin layer is 3 μm.

[0113] Comparative Example 1

[0114] 1. Prepare a resin with a thickness of 6 μm.

[0115] 2. The first aluminum foil and the second aluminum foil are evaporated on both sides of the resin by an evaporation process. The thickness of the first aluminum foil and the second aluminum foil is controlled to be 1 μm.

[0116] Comparative Example 2

[0117] 1. Prepare a first aluminum foil with a thickness of 1 μm, a second aluminum foil with a thickness of 1 μm, and a resin with a thickness of 6 μm.

[0118] 2. Attach the first aluminum foil and the second aluminum foil to both sides of the resin through a gluing process.

[0119] Test Method

[0120] 1. Binding strength test: The composite aluminum foils of Example 1, Example 2, Example 3 and Comparative Example 1 and Comparative Example 2 were tested by the hundred-grid method. The results are shown in Table 1:

[0121] Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Hundred Grid 5B 4B 5B 4B 4B

[0122] Table 1

[0123] It should be noted that the test steps of the 100-grid method include:

[0124] 1) Before testing, check that there is no abnormality in appearance, no discoloration, bubbles, cracks, falling off, etc., and wipe the surface of the substrate clean with a dust-free cloth;

[0125] 2) Hold the cutting tool and make the cut perpendicular to the test surface to prevent the blade from lifting the film. The cutting direction should be at a 45-degree angle to the sample. Apply force evenly to the cutting tool (the force should be such that the blade just penetrates the film and reaches the substrate) to form 10×10 continuous 1mm×1mm square grids.

[0126] 3) Use a dust-free cloth to clean the debris in the test area, evenly pull out a section of NICHI BAN CT405AP-24 tape, remove the front section, and then cut about 55mm of tape, place the center point of the tape above the grid, parallel to a set of cutting lines, and then use fingernails to flatten the part of the tape above the grid area to ensure that the tape is in good contact with the film layer (note that fingernails are not allowed to scratch the tape and the film layer), and the length of the tape is at least 20mm longer than the grid;

[0127] 4) Stick the tape on and let it stand for 90 seconds. Hold the dangling end of the tape and quickly pull it off within 0.5-1.0 seconds at an angle as close to 60 degrees as possible.

[0128] 5) Check the film peeling condition, and it is qualified when it reaches or exceeds 4B.

[0129] The Baige Method grading criteria are as follows:

[0130] 5B: The cutting edge is completely smooth, without any peeling;

[0131] 4B: A small amount of coating falls off at the intersection of the cuts, and the affected cross-cut area is no more than 5%;

[0132] 3B: Coating peels off at the intersection of the cuts and / or along the edges of the cuts, with the affected cross-cut area exceeding 5% but not exceeding 15%;

[0133] 2B: The film is partially or completely detached in large pieces along the cut edges and / or partially or completely detached on different parts of the grid, and the affected cross-cut area is greater than 15% but not greater than 35%;

[0134] 1B: The coating is peeling off in large pieces along the cut edges and / or some squares are partially or completely peeling off, and the affected cross-cut area is greater than 35% but not greater than 65%;

[0135] 0B: The degree of peeling exceeds 1B.

[0136] Through the above tests, it can be concluded that compared with the composite aluminum foil made by the evaporation process on the market, the composite aluminum foil made by the manufacturing method of the composite aluminum foil provided by the present application has better material properties and a more stable combination of the aluminum layer and the resin layer.

[0137] 2. Yield test:

[0138] Test method:

[0139] According to the methods of Example 1, Example 2, Example 3 and Comparative Example 1 and Comparative Example 2, 10 composite aluminum foils were prepared respectively, and the finished products that met the conditions of smooth surface and no damage were defined as good products. The ratio of the number of good composite aluminum foils to the total number of composite aluminum foils prepared was the yield of the composite aluminum foil. The test results are shown in Table 2:

[0140] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Yield 70％ 70％ 80％ 50％ 60％

[0141] Table 2

[0142] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship of terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside" and "outside" are based on the orientation or positional relationship described in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0143] What is disclosed above is only a preferred embodiment of the present application, and it certainly cannot be used to limit the scope of rights of the present application. Ordinary technicians in this field can understand that all or part of the processes of implementing the above embodiment and equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A composite aluminum foil, characterized in that: It includes a first aluminum layer, a resin layer and a second aluminum layer stacked in sequence; A porous layer is formed on the first aluminum layer and the second aluminum layer facing the resin layer. The porous layer includes a plurality of micropores, and the resin layer is at least partially fixedly connected in the micropores.

2. The composite aluminum foil according to claim 1, characterized in that: The inner wall surface of the micropore is formed with a plurality of inner connection holes, and the resin layer is fixedly connected in the inner connection holes.

3. The composite aluminum foil according to claim 2, characterized in that: The thickness of the porous layer is A, 0.1 μm≤A≤6 μm; and / or, The pore size of the micropore is B, 0.2 μm≤B≤2 μm; and / or, The density of the micropores distributed in the porous layer is C, 50EA. / mm 2 ≤C≤5000EA. / mm 2 and / or, The diameter of the inner connection hole is D, 10nm≤D≤100nm.

4. The composite aluminum foil according to claim 1, characterized in that The melting point of the resin used in the resin layer is E, 100°C≤E≤150°C.

5. The composite aluminum foil according to claim 4, characterized in that: The resin used in the resin layer includes: polypropylene and polyethylene, the weight of polypropylene is F, the weight of polyethylene is G, F:G=X:1, wherein 1≤X≤3.

6. The composite aluminum foil according to claim 1, characterized in that: The thickness of the first aluminum layer is L1, 1 μm≤L1≤8 μm; The thickness of the second aluminum layer is L2, 1 μm≤L2≤8 μm.

7. The composite aluminum foil according to claim 1, characterized in that: The thickness of the resin layer is L3, 0.5 μm≤L3≤8 μm.

8. The composite aluminum foil according to claim 1, characterized in that: The thickness of the resin layer is L3, 1 μm≤L3≤3 μm.

9. A method for manufacturing a composite aluminum foil, characterized in that: The steps include: The first aluminum foil is surface-treated to form a first aluminum layer, and the second aluminum foil is surface-treated to form a second aluminum layer, wherein a porous layer is formed on one side of the first aluminum layer and a porous layer is formed on one side of the second aluminum layer, and each of the porous layers includes a plurality of micropores; The first aluminum layer, the resin layer, and the second aluminum layer are stacked in sequence to form the composite aluminum foil, the porous layer of the first aluminum layer and the porous layer of the second aluminum layer are both arranged toward the resin layer, and at least a portion of the resin layer is fixedly connected in the micropores.

10. The method for producing a composite aluminum foil according to claim 9, characterized in that: The surface treatment of the first aluminum foil and the surface treatment of the second aluminum foil include the following steps: Covering one side of the first aluminum foil with a protective film to form a first single-sided coated aluminum foil; Covering one side of the second aluminum foil with a protective film to form a second single-sided coated aluminum foil; The first single-sided coated aluminum foil and the second single-sided coated aluminum foil are placed in concentrated sulfuric acid for electrolysis to form the first aluminum layer and the second aluminum layer, and a porous layer is formed on one side of the first aluminum layer and the second aluminum layer, and the porous layer includes a plurality of micropores, and the inner wall surface of the micropores is formed with a plurality of internal connecting holes.

11. The method for producing a composite aluminum foil according to claim 10, characterized in that: After the first single-sided film-coated aluminum foil and the second single-sided film-coated aluminum foil are placed in concentrated sulfuric acid for electrolysis, the following steps are also included: The porous layers of the first aluminum layer and the second aluminum layer are etched using an etching solution.

12. The method for producing a composite aluminum foil according to claim 10, wherein: The electrolysis voltage of the electrolysis treatment is V, 6v≤V≤20v; and / or, The electrolysis temperature of the electrolysis treatment is T, 20°C ≤ T ≤ 30°C; and / or, The electrolysis time of the electrolysis treatment is t, 10s≤t≤12000s; and / or, The mass fraction of the concentrated sulfuric acid is n, 10%≤n≤25%.

13. A battery, characterized in that: Comprising the composite aluminum foil as described in any one of claims 1 to 8.

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