Preparation method of an aluminum-plastic film for lithium ion soft package battery, aluminum-plastic film and application thereof

Abstract

The application discloses a preparation method of an aluminum-plastic film for lithium ion soft package battery packaging, the aluminum-plastic film and application of the aluminum-plastic film, and the preparation method comprises the following steps: treating a smooth surface of an aluminum foil layer with a silane coupling agent containing a carbon-carbon double bond, forming an organic-inorganic hybrid connecting layer through hydrolysis and condensation reaction of silicon hydroxyl groups, and then forming a heat sealing layer of a polymer through polymerization reaction of the polymer monomer containing the carbon-carbon double bond; and the steps of coating an adhesive to form an adhesive layer on the treated surface protection layer, and rolling and adhering the adhesive layer to a rough surface of the aluminum foil layer to obtain the aluminum-plastic film. The organic-inorganic hybrid connecting layer in the aluminum-plastic film prepared by the application is chemically connected to the aluminum foil layer and the heat sealing layer through Al-O-Si and C-C bonds respectively, so that the problem of physical adhesion between the layers being not firm and being prone to peeling is solved, and the packaging life of the lithium ion soft package battery is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium battery packaging materials, in particular to a preparation method of an aluminum-plastic film for lithium ion soft-pack battery packaging, an aluminum-plastic film and application thereof. BACKGROUND

[0002] With the development of information technology and energy revolution, lithium ion batteries, as an efficient and clean energy carrier, are applied to all aspects of human life. According to the application scenarios, lithium ion batteries can be divided into consumer batteries and power batteries. Consumer batteries are mainly used in notebook computers, mobile phones, small electric tools, electric toys and other fields. Power batteries are generally used to provide power for transportation tools and are mainly used in electric two-wheel / three-wheel vehicles, micro electric vehicles and new energy vehicles. Lithium ion batteries can be divided into soft-pack and hard-shell packaging according to the packaging form. Soft-pack batteries have a large market share in the consumer battery field due to their light weight, few structural parts and high energy density. However, they have a smaller share in the power battery field and have a decreasing trend year by year. The main reason is that, unlike consumer batteries, power batteries often require a long service life (8 years and more than 100,000 kilometers), and the current soft-pack battery packaging reliability is insufficient to meet the requirements.

[0003] The reason why the packaging reliability of soft-pack batteries does not meet the requirements of power batteries is that the lithium ion battery electrolyte contains a large amount of active organic solvent and lithium salt, which will produce a large amount of gas during long-term use, especially under extreme conditions such as high temperature and high voltage, resulting in an increase in the internal pressure of the battery. The existing aluminum-plastic film structure of soft-pack batteries is connected by an adhesive between the aluminum foil layer and the heat-sealing layer.

[0004] For example, the aluminum foil layer and the heat-sealing layer in patent CN111572135B are connected together by physical adhesion using polyurethane adhesive; patent CN111334199A uses a silane coupling agent such as methacryloxypropyl trimethoxysilane to form a chemical bond of Al-O-Si between the silane coupling agent and the aluminum foil layer, greatly improving the adhesion strength between the aluminum foil layer and the adhesive layer, but the adhesive layer and the heat-sealing layer are still physically bonded to each other; patent CN110103533A adds some prepolymers containing vinyl groups and active monomers based on patent CN111334199A, and the monomers are solidified into an adhesive layer by electron beam irradiation, increasing the adhesion strength, but the adhesive layer and the heat-sealing layer are still physically bonded together. These aluminum-plastic films connected together by physical adhesion are prone to peeling, especially under high internal pressure and large interfacial tension in the battery, resulting in packaging failure.

[0005] If an aluminum-plastic film can be prepared, the aluminum foil layer and the adhesive layer, the adhesive layer and the heat-seal layer are connected together by chemical bonds rather than physical adhesion, which will greatly improve the long-term reliability of the soft package battery packaging. Such soft package batteries can greatly improve the energy density of the battery and reduce the manufacturing cost compared to hard-shell batteries, and have broad application prospects. Therefore, it is necessary to develop a high-strength and long-life aluminum-plastic film for packaging lithium ion soft package batteries. SUMMARY

[0006] In order to solve the problems existing in the prior art, the purpose of the present application is to provide a preparation method of an aluminum-plastic film for packaging lithium ion soft package batteries, which can improve the packaging strength and reliability of the lithium ion soft package batteries, so that the aluminum foil layer and the adhesive layer, the adhesive layer and the heat-seal layer are connected by chemical bonds.

[0007] Another purpose of the present application is to provide an aluminum-plastic film for packaging lithium ion soft package batteries prepared by the preparation method.

[0008] Still another purpose of the present application is to provide the application of the aluminum-plastic film for packaging lithium ion soft package batteries.

[0009] In order to achieve the above purposes, the present application adopts the following technical solutions:

[0010] A preparation method of an aluminum-plastic film for packaging lithium ion soft package batteries, comprising the following steps:

[0011] a) treating the light side of the aluminum foil layer with a silane coupling agent containing carbon-carbon double bond, generating a layer of organic-inorganic hybrid connecting layer containing carbon-carbon double bond on the light surface of the aluminum foil layer through hydrolysis and condensation reaction of the silane coupling agent, to obtain a first composite layer film;

[0012] b) reacting the organic-inorganic hybrid connecting layer of the first composite layer film with a polymerizable monomer containing carbon-carbon double bond, generating a layer of polymer heat-seal layer on the surface of the organic-inorganic hybrid connecting layer, to obtain a second composite layer film;

[0013] c) coating an adhesive on the surface protection layer treated by corona to form an adhesive layer, and after drying, the adhesive layer is adhered to the rough side of the aluminum foil layer in the second composite film obtained in step b) by a pressure roller, and after curing, an aluminum-plastic film for packaging lithium ion soft package batteries is obtained.

[0014] In one specific embodiment, the silane coupling agent with carbon-carbon double bond in step a) has a structure of YSiX3, wherein X is a group capable of hydrolyzing to Si(OH)3, preferably a halogen atom or a group containing R-CH2-O-, more preferably chlorine, methoxy, ethoxy, methylethoxy or acetoxy; Y is a group containing at least one carbon-carbon double bond and capable of undergoing polymerization, preferably at least one of vinyl, propenyl, ethynyl; more preferably, the silane coupling agent with carbon-carbon double bond is selected from any one of γ-(methacryloyloxy)propyltrimethylsilane, γ-(methacryloyloxy)propyltriethylsilane, γ-(ethacryloyloxy)propyltrimethylsilane, γ-(ethacryloyloxy)propyltriethylsilane, vinyltrimethoxysilane, vinyltriethoxysilane, propenyltrimethoxysilane, propenyltriethoxysilane, vinyltri(b-methoxyethoxy)silane, propenyltri(b-methoxyethoxy)silane.

[0015] In one specific embodiment, the treatment with the silane coupling agent with carbon-carbon double bond in step a) comprises a step of brushing with the silane coupling agent with carbon-carbon double bond at a mass concentration of 0.5-2% and reacting at 25-80°C for 0.5-2h.

[0016] In one specific embodiment, the polymerizable monomer with carbon-carbon double bond in step b) is selected from at least one of ethylene, propylene, butylene, styrene, acrylic acid, acrylate, acrylonitrile, preferably ethylene, propylene, styrene or acrylate; preferably, the polymerizable monomer with carbon-carbon double bond is added in an amount of 20-10000 times the molar amount of the silane coupling agent with carbon-carbon double bond, more preferably, the reaction temperature in step b) is 40-85°C and the reaction time is 4-12h.

[0017] In one specific embodiment, the process conditions for the corona treatment of the surface protective layer in step c) are to bombard the surface protective layer with plasma particles at 5-80 electron volts for 0.1-5h, the drying temperature of the adhesive layer is 40-120°C and the drying time is 0.1-10h; the temperature for roll bonding is 30-120°C and the pressure is 0.5-100MPa; the process conditions for curing are to place in an oven and cure at 40-160°C for 1-8 days.

[0018] In one specific embodiment, the material of the surface protective layer is selected from one or more of polyamide, polyimide and polyester; the adhesive is selected from one or more of polyurethane adhesive, polyester adhesive or epoxy resin adhesive; the material of the aluminum foil layer is metal aluminum.

[0019] In a specific embodiment, the surface protective layer has a thickness of 8-60 microns, the adhesive layer has a thickness of 1-15 microns, and the aluminum foil layer has a thickness of 20-70 microns.

[0020] In another aspect, the application provides a lithium ion soft package battery packaging aluminum plastic film prepared by the above method.

[0021] In a specific embodiment, the aluminum plastic film comprises, in sequence, a surface protective layer, an adhesive layer, an aluminum foil layer, an organic-inorganic hybrid connecting layer, and a heat-sealing layer, preferably, the surface protective layer has a thickness of 8-60 microns, the adhesive layer has a thickness of 1-15 microns, and the aluminum foil layer has a thickness of 20-70 microns; preferably, the aluminum foil layer and the heat-sealing layer have a peeling strength of no less than 13 N / 15 mm.

[0022] In another aspect, the application provides a lithium ion soft package battery packaging aluminum plastic film prepared by the above method.

[0023] Compared with the prior art, the application has the following beneficial effects:

[0024] The hydrolysis and condensation reaction of the silane coupling agent containing carbon-carbon double bond in the preparation method of the application generates an organic-inorganic hybrid connecting layer containing carbon-carbon double bond on the smooth surface of the aluminum foil layer, and then the heat-sealing layer is prepared by the polymerization reaction of the polymerizable monomer containing carbon-carbon double bond and the carbon-carbon double bond on the organic-inorganic hybrid connecting layer, so that the one side of the organic-inorganic hybrid connecting layer of the aluminum plastic film is connected with the smooth surface of the aluminum foil layer through Al-O-Si chemical bond, and the other side is connected with the heat-sealing layer through C-C chemical bond, which connects the layers together through chemical bond, avoids the peeling and falling phenomenon caused by the traditional physical adhesive connection mode, and greatly improves the packaging reliability of the soft package battery cell. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 FIG. 1 is a structural schematic diagram of the lithium ion soft package battery packaging aluminum plastic film of the application.

[0026] In the figure, 1 is a surface protective layer, 2 is an adhesive layer, 3 is an aluminum foil layer, 4 is an organic-inorganic hybrid connecting layer, and 5 is a heat-sealing layer. DETAILED DESCRIPTION

[0027] In order to better understand the technical solutions of the application, the following examples will further illustrate the method provided by the application, but the application is not limited to the listed examples, and any known changes within the scope of the claims of the application should also be included.

[0028] As Figure 1As shown, an aluminum-plastic film for lithium ion soft package battery packaging includes a surface protection layer 1, an adhesive layer 2, an aluminum foil layer 3, an organic-inorganic hybrid connecting layer 4 and a heat sealing layer 5 which are sequentially stacked. The aluminum-plastic film for lithium ion soft package battery packaging has the characteristic that the organic-inorganic hybrid connecting layer 4 is connected to the aluminum foil layer 3 and the heat sealing layer 5 by chemical bonds, avoiding the peeling and falling phenomenon caused by the traditional physical adhesive connection mode, and greatly improving the packaging reliability of the soft package cell.

[0029] Specifically, the main component of the organic-inorganic hybrid connecting layer 4 of the aluminum-plastic film is a silane coupling agent, and the organic-inorganic hybrid connecting layer 4 is connected to the smooth surface of the aluminum foil layer 3 by Al-O-Si chemical bonds. The heat sealing layer 5 of the aluminum-plastic film is a polymer, and the heat sealing layer 5 is connected to the organic-inorganic hybrid connecting layer 4 by C-C chemical bonds.

[0030] The material of the surface protection layer 1 can be selected from conventional materials, for example, a combination of one or more of polyamide (such as polycaprolactam (nylon 6), polyhexamethylene adipate (nylon 66), polyhexamethylene sebacate (nylon 610), etc.), polyimide (such as polyimide prepared from pyromellitic dianhydride and diamino diphenyl ether, polyimide prepared from biphenyl tetracarboxylic dianhydride and diphenyl ether diamine, etc.) and polyester (poly(methyl acrylate), poly(ethyl acrylate) and poly(butyl acrylate), etc.). Typically, the thickness of the surface protection layer 1 is 8-60 μm, preferably 15-45 μm.

[0031] The material of the adhesive layer 2 can be selected from conventional materials, for example, a combination of one or more of polyurethane adhesive (such as 2,4-toluene diisocyanate, xylylene diisocyanate, methylene diisocyanate, etc.), polyester adhesive (such as poly(ethylene succinate), poly(butylene isophthalate), etc.) and epoxy adhesive (such as diphenol propane epoxy resin (bisphenol A), 4,4'-dihydroxydiphenylmethane epoxy resin (bisphenol F), etc.). Typically, the thickness of the adhesive layer 2 is 1-15 μm, preferably 3-10 μm.

[0032] The material of the aluminum foil layer 3 is metal aluminum, and typically the thickness of the aluminum foil layer 3 is 20-70 μm, preferably 25-50 μm.

[0033] The thickness of the organic-inorganic hybrid connecting layer and the heat sealing layer prepared by the method of the present application is not particularly limited, as long as the peeling strength of the aluminum foil layer and the heat sealing layer is not less than 13 N / 15 mm. Specifically, for example, the thickness of the organic-inorganic hybrid connecting layer 4 is 0.001-2 μm, preferably 0.1-1.5 μm; and the thickness of the heat sealing layer 5 is 10-100 μm, preferably 15-60 μm.

[0034] The interlayer chemically connected lithium ion soft package battery packaging aluminum plastic film is prepared by the following preparation method, specifically comprising the following steps:

[0035] a) treating the smooth surface of the aluminum foil layer 3 with a silane coupling agent containing carbon-carbon double bond, generating a layer of organic-inorganic hybrid connecting layer 4 containing carbon-carbon double bond on the smooth surface of the aluminum foil layer 3 through hydrolysis and condensation reaction of the silane coupling agent, to obtain a first composite layer film.

[0036] Specifically, in step a), the silane coupling agent containing carbon-carbon double bond has the structural formula YSiX3, wherein X is a group that can generate silanol (Si(OH)3) when hydrolyzed, for example, can be a halogen atom, such as chlorine, or a group containing R-CH2-O, such as methoxy, ethoxy, methylethoxy, acetoxy, etc., but not limited to. The silanol obtained by hydrolysis of the silane coupling agent reacts with the smooth surface of the aluminum foil layer 3 to form an organic-inorganic hybrid connecting layer 4.

[0037] Y is a group containing one or more carbon-carbon double bonds and capable of undergoing polymerization reaction, such as vinyl, propenyl, ethynyl, etc. The silane coupling agent containing carbon-carbon double bond with the structural formula YSiX3 is selected from any one of γ-(methacryloyloxy)propyltrimethylsilane, γ-(methacryloyloxy)propyltriethylsilane, γ-(ethacryloyloxy)propyltrimethylsilane, γ-(ethacryloyloxy)propyltriethylsilane, vinyltrimethoxysilane, vinyltriethoxysilane, propenyltrimethoxysilane, propenyltriethoxysilane, vinyltri(b-methoxyethoxy)silane, propenyltri(b-methoxyethoxy)silane, preferably γ-(methacryloyloxy)propyltrimethylsilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(b-methoxyethoxy)silane. The carbon-carbon double bond can further undergo polymerization reaction with a polymer monomer containing carbon-carbon double bond to generate a heat sealing layer 5.

[0038] In step a), a silane coupling agent containing carbon-carbon double bond with a mass concentration of 0.5-2% is brushed on the smooth surface of the aluminum foil layer 3, and hydrolysis reaction is carried out at 25-80°C for 0.5-2h, thereby generating a layer of organic-inorganic hybrid connecting layer 4 containing carbon-carbon double bond on the smooth surface of the aluminum foil layer 3, to obtain a first composite layer film.

[0039] b) reacting the first composite layer film with a polymer monomer containing carbon-carbon double bond, and generating a layer of polymer heat sealing layer 5 on the surface of the organic-inorganic hybrid connecting layer 4 through polymerization reaction between the carbon-carbon double bond in the organic-inorganic hybrid connecting layer 4 of the first composite layer film and the polymer monomer containing carbon-carbon double bond, to obtain a second composite layer film.

[0040] Specifically, the polymerizable monomer in step b) includes one or more monomers containing carbon-carbon double bond, the monomer species includes but is not limited to ethylene, propylene, butylene, styrene, acrylic acid, acrylate, acrylonitrile, etc., preferably ethylene, propylene, styrene or acrylate; preferably, the amount of the polymerizable monomer containing carbon-carbon double bond is 20-10000 times of the molar amount of the silane coupling agent containing carbon-carbon double bond, preferably 1000-6000 times, more preferably, the reaction temperature of step b) is 40-85℃, and the reaction time is 4-12h. In this step b), the carbon-carbon double bond groups of the original silane coupling agent in the organic-inorganic hybrid connecting layer 4 are polymerized with the polymer monomer containing carbon-carbon double bond, and a layer of polymer heat-sealing layer 5 is generated on the surface of the organic-inorganic hybrid connecting layer 4

[0041] c) coating an adhesive on the surface protective layer 1 after the corona treatment to form an adhesive layer 2, and after drying, the matte surface of the aluminum foil layer 3 in the second composite film is compounded with the adhesive layer 2 by a compression roller, and then aged.

[0042] Specifically, in step c), an adhesive is coated on the surface protective layer 1 after the corona treatment to form an adhesive layer 2, and after drying at 40-120℃ for 0.1-10h, the matte surface of the aluminum foil layer 3 in the second composite film is compounded with the adhesive layer 2 by a compression roller at 30-120℃ and a pressure of 0.5-100MPa, and then placed in an oven at 40-160℃ for aging for 1-8 days to obtain the aluminum-plastic film for lithium ion soft package battery of the present application. The corona treatment can refer to the conventional surface treatment process, for example, the surface protective layer is bombarded by plasma particles of several to several tens of electron volts for 0.1-5h.

[0043] The present application will be described in detail below with reference to specific examples, but does not constitute any limitation.

[0044] The main raw materials used in the examples and comparative examples are as follows:

[0045]

[0046]

[0047] The peel strength of the aluminum-plastic film was tested by the following method:

[0048] The peel strength of the aluminum-plastic film before and after soaking in electrolyte was tested, and the test conditions were as follows: the shear sample was a 15mm long strip, the aluminum foil layer and the heat-sealing layer were peeled off, and the peeling speed was 200mm / min.

[0049] Example 1

[0050] The surface protective layer is 12 μm of polycaprolactam (nylon 6), the adhesive layer is 1.5 μm of 2,4-toluene diisocyanate adhesive, and the aluminum foil layer is 25 μm of metal aluminum.

[0051] The preparation method of the aluminum-plastic film comprises the following steps:

[0052] a) A 1.5% mass concentration of a dilute solution of vinyl trimethoxysilane is prepared, and then the solution is coated on the smooth surface of the aluminum foil layer by using a 150 μm doctor blade. The solution is reacted at a temperature of 60 °C for 1.5 h, and an organic-inorganic hybrid connecting layer is grown on the smooth surface of the aluminum foil layer. The two layers are the first composite layer film containing carbon-carbon double bonds on the surface.

[0053] b) According to a 1:5000 molar ratio of vinyl trimethoxysilane to propylene, the first composite layer film is polymerized with propylene at 70 °C by adding 1% wt of potassium persulfate initiator for 8 h. After that, a heat-seal layer of polypropylene is grown on the surface of the first composite layer film, and a second composite layer film is obtained.

[0054] c) The surface of the nylon 6 is treated by corona treatment with 20 electron volts of plasma particle bombardment to obtain a treated surface protective layer. Then, a 1.5 μm thick layer of 2,4-toluene diisocyanate adhesive is coated on the treated surface of the surface protective layer to form an adhesive layer. After drying at 50 °C for 1 h, the aluminum foil layer in the second composite layer film is combined with the matte surface of the adhesive layer at 100 °C and 1 MPa by using a compression roller. Then, the sample is placed in an oven and aged at 70 °C for 5 days to obtain an aluminum-plastic film sample for lithium ion soft package batteries.

[0055] Example 2

[0056] In this example, an aluminum-plastic film for lithium battery packaging is prepared, which is basically the same as in Example 1, except that the concentration of the silane coupling agent is different, specifically 1.0% by mass; the reaction time after coating the silane coupling agent is different, specifically 0.5 h; and the reaction temperature after coating the silane coupling agent is different, specifically 80 °C.

[0057] Example 3

[0058] In this example, an aluminum-plastic film for lithium battery packaging is prepared, which is basically the same as in Example 1, except that the concentration of the silane coupling agent is different, specifically 2.0% by mass; the reaction time after coating the silane coupling agent is different, specifically 2 h; and the reaction temperature after coating the silane coupling agent is different, specifically 25 °C.

[0059] Example 4

[0060] The example prepared a kind of aluminum-plastic film for lithium battery package, it is basically identical with the embodiment 1, different is the kind of silane coupling agent is not identical, specifically γ-(methacryloyloxy) propyl triethyl silane;Silane coupling agent is not identical, specifically 0.5% mass concentration.

[0061] Example 5

[0062] The example prepared a kind of aluminum-plastic film for lithium battery package, it is basically identical with the embodiment 1, different is the kind of silane coupling agent is not identical, specifically γ-(methacryloyloxy) propyl triethyl silane;Silane coupling agent is not identical, specifically 0.5% mass concentration.

[0063] Example 6

[0064] The example prepared a kind of aluminum-plastic film for lithium battery package, it is basically identical with the embodiment 1, different is the kind of silane coupling agent is not identical, specifically γ-(methacryloyloxy) propyl triethyl silane;Silane coupling agent is not identical, specifically 0.5% mass concentration.

[0065] Example 7

[0066] The example prepared a kind of aluminum-plastic film for lithium battery package, it is basically identical with the embodiment 1, different is the kind of silane coupling agent is not identical, specifically γ-(methacryloyloxy) propyl triethyl silane;Silane coupling agent is not identical, specifically 0.5% mass concentration.

[0067] Comparative example 1

[0068] Surface protective layer is 12 μm of polycaprolactam (nylon 6), adhesive layer is 1.5 μm of 2,4-toluene diisocyanate adhesive, aluminum foil layer is 25 μm of metal aluminum, connecting layer is 2 μm of polyurethane adhesive, heat-sealing layer is 30 μm of polypropylene. The comparative example is the most conventional preparation method of aluminum-plastic film at present, and the aluminum foil layer and the heat-sealing layer are connected by polyurethane adhesive.

[0069] The preparation method of aluminum-plastic film includes the following steps:

[0070] The preparation method comprises the following steps: coating a 2 μm polyurethane adhesive on the smooth surface of the aluminum foil layer to obtain a first composite layer film, and then attaching a polypropylene heat sealing layer to the polyurethane adhesive side of the first composite layer film to obtain a second composite layer film. The surface protection layer is obtained by performing corona treatment on the surface of nylon 6 using 20 electron volts of plasma particle bombardment, and then coating a 1.5 μm thick 2,4-toluene diisocyanate adhesive on the treated surface of the surface protection layer to form an adhesive layer. After drying at 50°C for 1 h, the aluminum foil layer rough surface in the second composite layer film is compounded with a pressure roller under the conditions of 100°C and 1 MPa, and then placed in an oven for curing at 70°C for 5 days to obtain an aluminum-plastic film sample for lithium ion soft package battery packaging.

[0071] Comparative Example 2

[0072] The surface protection layer is 12 μm of polycaprolactam (nylon 6), the adhesive layer is 1.5 μm of 2,4-toluene diisocyanate adhesive, the aluminum foil layer is 25 μm of metal aluminum, the connecting layer is 2 μm of adhesive composed of acrylic resin and silane coupling agent, and the heat sealing layer is 30 μm of polypropylene. In this comparative example, the aluminum foil layer and the heat sealing layer are connected by using the corrosion-resistant adhesive for lithium batteries in CN111334199A.

[0073] The preparation method comprises the following steps: adding acrylic resin and silane coupling agent into a solvent, heating to 60°C, and stirring and mixing for 1-2 h until a homogeneous solution is formed. Crosslinking agent and nano manganese dioxide are added to the above-mentioned solution, further solvent is added, heated to 60°C, and stirred and mixed for 2-4 h until a homogeneous solution is formed. A 2 μm coating layer is coated on the surface of the aluminum foil to obtain a first composite layer film, and then a heat sealing layer is attached to the side of the adhesive composed of acrylic resin and silane coupling agent on the first composite layer film to obtain a second composite layer film. The surface protection layer is obtained by performing corona treatment on the surface of nylon 6 using 20 electron volts of plasma particle bombardment, and then coating a 1.5 μm thick 2,4-toluene diisocyanate adhesive on the treated surface of the surface protection layer to form an adhesive layer. After drying at 50°C for 1 h, the aluminum foil layer rough surface in the second composite layer film is compounded with a pressure roller under the conditions of 100°C and 1 MPa, and then placed in an oven for curing at 70°C for 5 days to obtain an aluminum-plastic film sample for lithium ion soft package battery packaging.

[0074] Comparative Example 3

[0075] The surface protective layer is 12 μm of polycaprolactam (nylon 6), the adhesive layer is 1.5 μm of 2,4-toluene diisocyanate adhesive, the aluminum foil layer is 25 μm of metal aluminum, the connecting layer is silane coupling agent + acrylic acid, and the heat sealing layer is a polypropylene layer containing 1.8% by weight of a sensitizer pentaerythritol triacrylate. In the comparative example, the aluminum foil layer and the heat sealing layer are bonded by the connecting method in CN110103533A.

[0076] The preparation method comprises the following steps: impregnating the aluminum foil with a 3% mass fraction of vinyltrimethoxysilane solution for 30-60 seconds, and drying at 120°C for 1-2 minutes by blowing to complete passivation. The heat sealing layer is selected from a cast polypropylene film containing 1.8% by weight of a sensitizer pentaerythritol triacrylate. The heat sealing layer and the passivated aluminum foil are respectively unwound in parallel on a two-layer film coating compounder, a special adhesive is coated on the lower surface of the heat sealing layer by a solvent-free coating technique, and the coating amount of each layer is controlled to be 2.5 g / m 2 ; the passivated aluminum foil, the adhesive layer and the heat sealing layer are laminated and compacted by a pressure roller; and the special adhesive is cured by electron beam irradiation, the electron beam energy used is 500 keV, and the absorbed dose is 30 kGy. After irradiation, a second composite layer film is obtained. The surface protective layer is obtained by treating the surface of nylon 6 with 20 electron volts of plasma particles, and then scraping 1.5 μm thick 2,4-toluene diisocyanate adhesive on the surface of the surface protective layer to form an adhesive layer. After drying at 50°C for 1 h, the aluminum foil layer of the second composite layer film is laminated with the adhesive layer at 100°C and 1 MPa by a pressure roller, and then placed in an oven for 5 days at 70°C to obtain an aluminum-plastic film sample for lithium ion soft package batteries.

[0077] Application performance test 1

[0078] The aluminum-plastic film samples obtained in the examples and comparative examples are subjected to peel strength experiments. The test conditions are that the shearing sample is a 15 mm long strip, the aluminum foil layer (3) and the heat sealing layer (5) are peeled off, and the peel speed is 200 mm / min. The peel strength of each sample is shown in Table 1.

[0079] Table 1 Fresh aluminum-plastic film peel test data

[0080]

[0081] From the experimental data of the peel strength, it can be seen that the aluminum-plastic film in the examples of the present application has a much higher strength than the aluminum-plastic film (comparative examples 1-3) connected by physical adhesion.

[0082] Application performance test 2

[0083] The aluminum-plastic film samples obtained in the examples and comparative examples were first soaked in electrolyte (EC:EMC=3:7, 1M LiPF6) at 80℃ for 24h, then taken out, wiped dry and subjected to peeling strength test. The test conditions were: the shearing sample was a 15mm long strip, the aluminum foil layer and the heat-sealing layer were peeled, and the peeling speed was 200mm / min. The peeling strength of each sample obtained is shown in Table 2.

[0084] Table 2 Peeling test data of aluminum-plastic film after electrolyte soaking

[0085]

[0086] From the peeling strength experimental data after electrolyte soaking, it can be seen that, compared with the conventional physically glued aluminum-plastic film, the aluminum-plastic film prepared by the method of chemical bonding in the present application has basically no change in peeling strength under the dual action of electrolyte soaking and high temperature, greatly improves the packaging reliability of lithium ion batteries, and is conducive to the promotion of subsequent lithium ion soft-pack power batteries.

[0087] Although the content of the present application has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as limiting the present application. Those skilled in the art can understand that, under the teaching of the present specification, some modifications or adjustments can be made to the present application. These modifications or adjustments should also be within the scope defined by the claims of the present application.

Claims

1. A method for producing an aluminum laminate film for lithium-ion soft-pack battery packaging, characterized by, The method comprises the following steps: a) treating the shiny side of the aluminum foil layer with a silane coupling agent containing carbon-carbon double bond, generating a layer of organic-inorganic hybrid connecting layer containing carbon-carbon double bond on the shiny side of the aluminum foil layer through the hydrolysis and condensation reaction of the silane coupling agent, obtaining a first composite layer film; b) reacting the organic-inorganic hybrid connecting layer of the first composite layer film with a polymerizable monomer containing carbon-carbon double bond, generating a layer of polymer heat-sealing layer on the surface of the organic-inorganic hybrid connecting layer, obtaining a second composite layer film; c) coating an adhesive on the surface protection layer treated by corona to form an adhesive layer, and after drying, the adhesive layer is adhered to the matte side of the aluminum foil layer in the second composite layer film obtained in step b) by a pressure roller, and after curing, an aluminum-plastic film for lithium ion soft package battery is obtained.

2. The production method according to claim 1, characterized by, The silane coupling agent containing carbon-carbon double bond in step a) has a structural formula of YSiX3, wherein X is a group capable of hydrolyzing to Si(OH)3; Y is a group containing at least one carbon-carbon double bond and capable of polymerization reaction.

3. The production method according to claim 2, characterized by, X is a halogen atom or a group containing R-CH2-O-; Y is selected from at least one of vinyl and propenyl.

4. The production method according to claim 2, characterized by, Y can also be an ethynyl group.

5. The preparation method according to claim 3, characterized in that, X is chlorine, methoxy, ethoxy, methylethoxy or acetoxy.

6. The method of any one of claims 2 to 5, wherein the method further comprises, The silane coupling agent containing carbon-carbon double bond is selected from any one of γ-(methacryloyloxy)propyltrimethylsilane, γ-(methacryloyloxy)propyltriethylsilane, γ-(ethacryloyloxy)propyltrimethylsilane, γ-(ethacryloyloxy)propyltriethylsilane, vinyltrimethoxysilane, vinyltriethoxysilane, propenyltrimethoxysilane, propenyltriethoxysilane, vinyltri(b-methoxyethoxy)silane, and propenyltri(b-methoxyethoxy)silane.

7. The production method according to claim 1 or 2, characterized by, The treatment with the silane coupling agent containing carbon-carbon double bond in step a) comprises the step of brushing the silane coupling agent containing carbon-carbon double bond with a mass concentration of 0.5-2% and reacting at 25-80°C for 0.5-2h.

8. The method of claim 1, wherein, The polymerizable monomer containing carbon-carbon double bond in step b) is selected from at least one of ethylene, propylene, butylene, styrene, acrylic acid, acrylate, and acrylonitrile.

9. The production method according to claim 8, characterized by, The polymerizable monomer containing carbon-carbon double bond in step b) is selected from ethylene, propylene, styrene or acrylate.

10. The preparation method according to claim 8, characterized in that, The amount of the polymerizable monomer containing carbon-carbon double bond added is 20-10000 times the molar amount of the silane coupling agent containing carbon-carbon double bond.

11. The method of claim 10, wherein, The reaction temperature of step b) is 40-85°C, and the reaction time is 4-12h.

12. The method of claim 1, wherein, The process conditions for the corona treatment of the surface protection layer in step c) are that the surface protection layer is bombarded with plasma particles of 5 to 80 electron volts for 0.1-5h, the drying temperature of the adhesive layer is 40-120°C, and the drying time is 0.1-10h; the temperature for the pressure roller adhesion is 30-120°C, and the pressure is 0.5-100MPa; and the process conditions for the curing are that the curing is carried out in an oven at 40-160°C for 1-8 days.

13. The method of claim 1, wherein, The material of the surface protective layer is selected from one or more of polyamide, polyimide and polyester; the adhesive is selected from one or more of polyurethane adhesive, polyester adhesive or epoxy resin adhesive; and the material of the aluminum foil layer is metal aluminum.

14. The method of claim 1, wherein, The thickness of the surface protective layer is 8-60 μm, the thickness of the adhesive layer is 1-15 μm, and the thickness of the aluminum foil layer is 20-70 μm.

15. The aluminum-plastic film for packaging lithium ion soft package batteries prepared by the preparation method of any one of claims 1-14.

16. The lithium-ion soft-pack battery packaging aluminum laminate film according to claim 15, characterized by, The aluminum-plastic film comprises, in sequence, a surface protective layer, an adhesive layer, an aluminum foil layer, an organic-inorganic hybrid connecting layer and a heat-sealing layer.

17. The lithium-ion soft-pack battery packaging aluminum laminate film according to claim 16, characterized by, The thickness of the surface protective layer is 8-60 μm, the thickness of the adhesive layer is 1-15 μm, and the thickness of the aluminum foil layer is 20-70 μm.

18. The lithium-ion soft-pack battery packaging aluminum laminate film according to claim 17, characterized by, The peeling strength of the aluminum foil layer and the heat-sealing layer is not less than 13 N / 15 mm.

19. The application of the aluminum-plastic film for packaging lithium ion soft package batteries prepared by the preparation method of any one of claims 1-14 or the aluminum-plastic film for packaging lithium ion soft package batteries of any one of claims 15-18 in packaging lithium ion soft package batteries.

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