High-barrier lithium battery aluminum-plastic flexible film material and preparation method thereof

Abstract

The application relates to the technical field of battery packaging, in particular to a high-barrier lithium battery aluminum-plastic flexible film material and a preparation method thereof. The high-barrier lithium battery aluminum-plastic flexible film material comprises, from outside to inside, a fluorine-containing graft-modified nylon blending layer, a composite barrier A layer, a chemically activated aluminum foil layer, a composite barrier B layer and a modified PP layer; each layer is respectively prepared by grafting, blending or activating with specific raw materials, and a key functional structure is constructed by a fluorine component and a silane reagent. In the preparation, each functional layer is first prepared, the composite barrier A layer is coated on the nylon layer and hot-pressed, the activated aluminum foil is attached after acid treatment, the composite barrier B layer is coated on the other side of the aluminum foil and pre-solidified, and finally the modified PP layer is attached for overall hot pressing, vacuum drying and curing. The material realizes high barrier, strong interlayer bonding, electrolyte resistance and excellent deep drawing formability through the cooperation of multiple layers of covalent bonds and fluorine barriers, meets the long-term use requirements of soft-pack lithium batteries, the preparation process is controllable, and the material is beneficial to large-scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery packaging, and particularly relates to a high-barrier lithium battery aluminum-plastic soft film material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of new energy vehicles, energy storage batteries and other fields, the requirements for energy density and cycle life of lithium batteries continue to increase. Soft-pack lithium batteries become the mainstream direction due to their light structure and high energy density. The barrier performance, interlayer bonding stability and corrosion resistance of aluminum-plastic soft film as the core packaging material of soft-pack batteries directly determine the safety and service life of the batteries. The aluminum-plastic films on the current market generally face the problem of permeation of corrosive gases such as water vapor, oxygen and H2S generated inside the battery. These gases can easily cause oxidation of electrode materials and decomposition of electrolyte, leading to capacity attenuation, bulging and even short circuit risk of the battery. Therefore, high-barrier properties of aluminum-plastic films are required.

[0003] The interlayer bonding of existing aluminum-plastic films mainly depends on a single adhesive or physical bonding. The adhesive is prone to swelling and aging under long-term immersion in electrolyte and high-temperature environment, resulting in a decrease in interlayer peeling strength and delamination failure. At the same time, the barrier layer of traditional aluminum-plastic films lacks targeted functional design, and the introduction of fluorine elements is insufficient or unevenly distributed, making it difficult to form a dense hydrophobic and oleophobic barrier and effectively blocking the infiltration of electrolyte and the permeation of corrosive gases. In addition, due to the large polarity difference between the PP layer as the inner heat-sealing layer and the barrier layer, there are insufficient bonding sites, and the heat-sealing strength and electrolyte resistance stability are difficult to balance, further limiting the application of aluminum-plastic films in high-performance lithium batteries.

[0004] Although some improved technologies attempt to improve performance through graft modification or multi-layer compounding, they fail to achieve the synergistic optimization of "barrier layer-bonding system-corrosion resistance": either the fluorocarbon chain is only introduced in a single layer, which cannot form a whole-system protection; or the interlayer bonding only relies on a single chemical bond, which has poor stress dispersion ability; or the aluminum foil surface is not sufficiently activated, and the combination with the organic barrier layer is not firm, resulting in short boards in overall performance, which is difficult to meet the stringent requirements of long-term cycle use of high-energy-density lithium batteries. Therefore, it is an urgent need in the industry to develop an aluminum-plastic soft film material with high barrier, strong bonding, electrolyte resistance and corrosion resistance. SUMMARY

[0005] The present application aims to solve the problems in the prior art and provides a high-barrier lithium battery aluminum-plastic soft film material and a preparation method thereof.

[0006] To achieve the above purpose, the present application provides a high-barrier lithium battery aluminum-plastic soft film material, which comprises, from the outside to the inside, a fluorine-containing graft-modified nylon blended layer, a composite barrier A layer, a chemically activated aluminum foil layer, a composite barrier B layer and a modified PP layer.

[0007] The fluorine-containing graft-modified nylon blend layer is mainly composed of nylon 66 and polybutylene terephthalate blend, and 2H, 2H, 3H, 3H-perfluoroundecanoic acid is grafted through glycidyl methacrylate as a graft bridge;

[0008] The composite barrier A layer refers to a blend of γ-aminopropyl triethoxysilane, 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride graft and 3-isocyanate propyl trimethoxysilane;

[0009] The chemically activated aluminum foil layer is obtained by alkali washing and acid washing of an aluminum foil;

[0010] The composite barrier B layer refers to a mixture of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride graft after hydrolysis;

[0011] The modified PP layer is mainly composed of homopolymer PP, and maleic anhydride and hydroxyethyl methacrylate are grafted.

[0012] Further, the application also provides a preparation method of the high-barrier lithium battery aluminum-plastic soft film material, which comprises the following steps:

[0013] (1) After drying and removing water from nylon 66, polybutylene terephthalate, glycidyl methacrylate and 2H, 2H, 3H, 3H-perfluoroundecanoic acid, they are added into a high-speed mixer, and then dicumyl peroxide and antioxidant 1010 are added, and stirred for 10-20 min at room temperature until they are uniformly mixed, and then they are put into a double-screw extruder, and then melt extruded, and then cooled into a film by a casting roll to obtain a fluorine-containing graft-modified nylon blend layer;

[0014] (2) Under nitrogen protection, γ-aminopropyl triethoxysilane and anhydrous potassium carbonate are added into anhydrous ethyl acetate, cooled to 0℃, and then 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride is added under stirring, and then reacted for 30-60 min, and then the room temperature is restored, and then stirring is continued for 1-2 h to obtain a graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride, and then the potassium carbonate is removed by filtration, and then 3-isocyanate propyl trimethoxysilane is added, and then stirred for 10-30 min until they are uniformly mixed, and then the total content of γ-aminopropyl triethoxysilane, 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride graft and 3-isocyanate propyl trimethoxysilane in the system is adjusted to 30wt%-40wt% by adding solvent or reducing pressure concentration to obtain a composite barrier A layer;

[0015] (3) immerse the aluminum foil into 5wt% NaOH solution, heat to 50-60℃, oscillation reaction for 1-3min, then rinse with deionized water until pH is neutral, then immerse into 3wt% HNO3 solution, oscillation reaction for 30-60s at room temperature, then rinse with deionized water until pH is neutral, dry to obtain the chemically activated aluminum foil layer;

[0016] (4) under nitrogen protection, add γ-aminopropyl triethoxysilane and anhydrous potassium carbonate into anhydrous ethanol, cool to 0℃, add 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride under stirring, react for 30-60min, restore to room temperature, continue to stir for 1-2h, to obtain the graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride, remove potassium carbonate by filtration, add dilute hydrochloric acid to adjust pH to 3-4, continue to stir for 4-6h, then adjust the content of the graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride in the system to 30wt%-40wt% by adding solvent or reducing pressure concentration, to obtain the composite barrier B layer;

[0017] (5) after drying and removing water from the homopolymer polypropylene powder, add maleic anhydride, hydroxyethyl methacrylate and dicumyl peroxide into a high-speed mixer, stir for 10-20min until mixed uniformly, then put into a twin-screw extruder, melt extrude, cool into a film by a casting roll, to obtain the modified PP layer;

[0018] (6) apply the composite barrier A layer on one side of the fluorine-containing grafted and modified nylon blend layer to form a wet film A, immediately enter a hot press roller group, hot press for 10-15s; then spray dilute hydrochloric acid solution on the side where the composite barrier A layer is located, place horizontally for 10-20min; then place the chemically activated aluminum foil layer thereon, apply the composite barrier B layer on the other side of the chemically activated aluminum foil layer to form a wet film B, send into a pre-solidification box for pre-solidification, after pre-solidification, place the modified PP layer on the other side of the composite barrier B layer, hot press composite molding by a hot press machine, to obtain a five-layer composite film; finally, vacuum dry the five-layer composite film, mature at room temperature and 50% environmental humidity for 48h, cut and roll up to obtain the high-barrier lithium battery aluminum-plastic soft film material.

[0019] Preferably, the nylon 66, polybutylene terephthalate, glycidyl methacrylate, 2H, 2H, 3H, 3H-perfluoroundecanoic acid, dicumyl peroxide and antioxidant 1010 in (1) are in a weight ratio of 1:0.3-0.5:0.03-0.07:0.06-0.15:0.01-0.03:0.01-0.05.

[0020] Preferably, the temperature of the first zone in the twin-screw extruder in (1) is 220-240℃, the temperature of the second zone is 240-250℃, the temperature of the third zone is 250-260℃, and the temperature of the die head is 250-270℃, and the screw rotation speed is 100-300r / min.

[0021] Preferably, the thickness of the fluorine-containing graft-modified nylon blend layer obtained in (1) is 25-30μm.

[0022] Preferably, the molar ratio of γ-aminopropyl triethoxysilane, anhydrous potassium carbonate, and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride in (2) is 1:1.5-2:1.

[0023] Preferably, the weight ratio of γ-aminopropyl triethoxysilane, anhydrous ethyl acetate, and 3-isocyanate propyl trimethoxysilane in (2) is 1:8-12:0.5-1.

[0024] Preferably, the graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride in (2) is obtained by the following chemical reaction equation:

[0025] .

[0026] Preferably, the thickness of the aluminum foil in (3) is 10μm.

[0027] Preferably, the molar ratio of γ-aminopropyl triethoxysilane, anhydrous potassium carbonate, and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride in (4) is 1.3-1.7:1.5-2:1.

[0028] Preferably, the weight ratio of γ-aminopropyl triethoxysilane and anhydrous ethanol in (4) is 1:8-12.

[0029] Preferably, the concentration of dilute hydrochloric acid in (4) is 1mol / L.

[0030] Preferably, the weight ratio of homopolymer polypropylene powder, maleic anhydride, hydroxyethyl methacrylate, and dicumyl peroxide in (5) is 1:0.02-0.07:0.02-0.07:0.003-0.007.

[0031] Preferably, the melt index of the homopolymer polypropylene powder in (5) is 3g / 10min.

[0032] Preferably, the temperature of the first zone in the twin-screw extruder in (5) is 140-160℃, the temperature of the second zone is 160-170℃, the temperature of the third zone is 170-180℃, and the temperature of the die head is 170-190℃, and the screw rotation speed is 200-300r / min.

[0033] Preferably, the thickness of the modified PP layer obtained in (5) is 35-40 μm.

[0034] Preferably, the thickness of the wet film A in (6) is 3-5 μm, and the parameters of the hot-press roller group are temperature 160-170 ℃, pressure 0.3-0.5 MPa, and roller speed 3-7 m / min.

[0035] Preferably, the pH of the dilute hydrochloric acid solution in (6) is 3-4, and the spraying amount is 5-10 g / m 2 .

[0036] Preferably, the thickness of the wet film B in (6) is 3-7 μm, and the pre-solidification conditions are temperature 80-90 ℃, pressure 0.1-0.3 MPa, and time 10-20 min.

[0037] Preferably, the hot-press parameters of the hot press in (6) are temperature 180-190 ℃, pressure 0.5-0.7 MPa, and time 10-30 s.

[0038] Preferably, the mechanism of the high-barrier lithium battery aluminum-plastic soft film material in the present application is explained as follows:

[0039] The fluorine-containing grafted modified nylon blend layer: this layer takes nylon 66 and polybutylene terephthalate (PBT) as a blend matrix, wherein the hydrogen bond network formed by the intermolecular amide bond of nylon 66 endows the layer with excellent puncture resistance, which can resist mechanical damage during battery assembly, and PBT reduces the overall water absorption to reduce the erosion of the inner layer by environmental moisture; at the same time, this layer also grafts 2H, 2H, 3H, 3H-perfluoroundecanoic acid to the surface of the blend matrix through the reaction of epoxy and carboxyl groups by taking glycidyl methacrylate (GMA) as a grafting bridge, and the exposed fluorocarbon chain of 2H, 2H, 3H, 3H-perfluoroundecanoic acid has extremely strong hydrophobic and oleophobic properties, forming a dense fluorine-rich surface layer that not only reduces the water vapor permeability, but also blocks the swelling erosion of the electrolyte; in addition, GMA is designed in excess to ensure that the excess epoxy group is ring-opened to generate hydroxyl groups during the extrusion process, providing key active sites for subsequent bonding with the composite barrier A layer, avoiding the problem of easy delamination of physical adhesion of traditional nylon layers due to the lack of reactive groups;

[0040] Composite barrier A layer: a graft of γ-aminopropyltriethoxysilane (KH550) and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride, and 3-isocyanate propyl trimethoxysilane (IPTS) is blended to form the composite barrier A layer. The core function is to realize the directional connection of the outer nylon and the intermediate aluminum foil, and to supplement the barrier property. From the bonding mechanism, the isocyanate group in IPTS can react with the hydroxyl group on the surface of the nylon layer under the condition of hot pressing at 160-170°C to generate a -NH-CO-O- bond, which provides stable binding force for the "nylon-A layer". At the same time, the siloxane group in the graft can generate silanol after subsequent hydrolysis catalyzed by dilute hydrochloric acid, which can hydrolyze and condense with the hydroxyl group on the surface of the chemically activated aluminum foil to form a Si-O-Al covalent bond, ensuring that the aluminum foil and the A layer have no mechanical peeling risk. In terms of barrier enhancement, the introduced fluorocarbon chain is uniformly dispersed in the A layer, forming a "double-layer fluorine barrier structure" with the fluorine group of the nylon layer, further reducing the permeation rate of corrosive gases and assisting the aluminum foil in improving the corrosion resistance.

[0041] Chemically activated aluminum foil layer: the chemically activated aluminum foil layer is the barrier core of the entire film material, and its action mechanism is based on surface activation treatment and the dense characteristics of the metal. The aluminum foil is first washed with 5wt% NaOH solution to remove surface oil and loose oxide layer. Then it is washed with 3wt% HNO3 solution to further etch the surface to form a hydroxylated rough surface, and the hydroxyl density is increased. This surface treatment not only provides sufficient reaction sites for the silanol of the composite barrier A / B layer, but also enhances the interlayer mechanical engagement through the rough structure to avoid interlayer slip. From the barrier mechanism, the aluminum foil as a dense metal layer has a permeability close to 0 for water vapor, oxygen, and corrosive gases, which is a key barrier to prevent the entry of external corrosive media into the battery interior. Compared with the traditional unactivated aluminum foil, the bonding force between the activated aluminum foil and the barrier layer is improved, effectively solving the industry pain point of "aluminum foil corrosion leading to barrier failure";

[0042] Composite barrier B layer: Grafted by KH550, KH550-2H, 2H, 3H, 3H-perfluoroundecanoyl chloride (molar ratio of KH550 to 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride 1.3-1.7:1), the core function is to connect the aluminum foil and the modified PP in the inner layer, and to retain active amino groups for subsequent bonding; in terms of bidirectional bonding, the silicon hydroxyl groups generated by the hydrolysis of KH550 in the B layer can undergo Si-O-Al condensation reaction with the hydroxyl groups on the other side of the aluminum foil surface to form a stable "aluminum foil-B layer" connection, achieving double-sided coating of the aluminum foil and avoiding direct contact of the aluminum foil with the electrolyte; at the same time, the excess design of KH550 ensures that free amino groups are retained after hydrolysis, which can undergo imidization reaction with maleic anhydride in the modified PP layer under the condition of hot pressing at 180-190℃ to generate -NH-CO-O-CO- bond, solving the cold flow delamination problem caused by the mismatch of polarity between PP and barrier layer; in terms of barrier enhancement, the fluorocarbon chain in the B layer forms a "fluorine barrier on both sides of the aluminum foil" with the A layer, further reducing gas permeation and forming a dense organic-inorganic hybrid barrier network, which further reduces the water vapor transmission rate compared to a single aluminum foil structure.

[0043] Modified PP layer: Using homopolymer PP as the matrix, grafted with MAH and hydroxyethyl methacrylate (HEMA), it is the core heat-sealing inner layer of battery packaging, and its mechanism revolves around heat-sealing performance and electrolyte resistance. In terms of heat sealing, the melting temperature of homopolymer PP is suitable for battery packaging process, and the PP layer melts and flows during hot pressing, which can fill the small gaps in the packaging interface and form a leak-free heat-sealing seam; the hydroxyl groups in HEMA can also form hydrogen bonds with the amide bonds in the B layer, further improving the interface sealing performance after heat sealing; in terms of electrolyte resistance and bonding, the anhydride groups formed after MAH grafting are the core reaction sites with the amino groups in the B layer, and after imidization reaction, the PP layer and the B layer become an integrated structure, effectively preventing electrolyte from penetrating between the layers; at the same time, the non-polar nature of the PP molecular chain makes it excellent in electrolyte swelling resistance, with a small volume change rate after long-term soaking, ensuring that the inner layer remains stable during the battery life cycle.

[0044] Interlayer synergy is the key to realizing high barrier, high bonding force and high mechanical compatibility of materials, mainly reflected in the synergy of three dimensions of bonding network, barrier performance and mechanical performance. In terms of bonding network synergy, the continuous covalent bond network is formed through "urethane bond of nylon-A layer → Si-O-Al bond of A layer-aluminum foil and aluminum foil-B layer → imide bond of B layer-PP layer", which ensures high overall peel strength; at the same time, the amide bond of nylon layer, the hydroxyl group of HEMA of PP layer and the polar group of barrier layer form intermolecular hydrogen bond, which helps to disperse the interfacial stress, so that the material can withstand higher impact depth (meet the battery forming requirement) without delamination. In terms of barrier performance synergy, the fluorocarbon chain of the outer layer (nylon+A layer) and the inner layer (B layer+PP) forms a bidirectional fluorine barrier, which reduces the contact of water vapor / electrolyte and the interface by virtue of hydrophobic and oleophobic properties; the middle aluminum foil provides absolute barrier to block gas / liquid penetration; the Si-O-Si / Si-O-Al hybrid network formed after hydrolysis of A / B layer fills the small defects on the surface of aluminum foil, further reducing the penetration channel, and the water vapor transmission rate and corrosion rate of the material are far superior to those of traditional aluminum plastic film. In terms of mechanical performance synergy, the material presents a "rigidity-flexibility" gradient decrease from the outside to the inside: the nylon layer provides puncture resistance, the A / B layer has both rigidity and flexibility, the aluminum foil provides structural support, and the PP layer provides heat-seal flexibility. This gradient matching ensures that the material can resist external mechanical impact and adapt to the bending and impact depth of the battery packaging forming process.

[0045] The beneficial effects of the present application are:

[0046] 1. The present application realizes firm connection of each functional layer by constructing multiple continuous bonding networks and matching intermolecular hydrogen bond to assist stress dispersion. The hydroxyl group of the fluorine-containing grafted and modified nylon blend layer, the surface hydroxyl group of the chemically activated aluminum foil and the active groups of the composite barrier A / B layer react precisely, eliminating the interlayer gap and avoiding the aging delamination problem caused by physical adhesion or single adhesive, ensuring that the material always maintains complete structure during long-term use, bending and forming process, and the interlayer bonding force is stable and reliable.

[0047] 2. The present application introduces a bidirectional hydrophobic and oleophobic barrier by introducing a fluorocarbon chain in the whole system of "nylon layer+A / B layer", combines the absolute physical barrier of chemically activated aluminum foil and the defect plugging of Si-O-Si hybrid network, and constructs a triple barrier system. This system can effectively block water vapor, oxygen and other external gases, and at the same time resist the penetration of H2S and other corrosive gases generated inside the battery, avoid electrode oxidation and electrolyte decomposition, provide all-round protection for lithium batteries, and prolong the cycle life of the battery.

[0048] 3.The fluorocarbon chain of the composite barrier B layer in the application reduces the contact of electrolyte with the interface between the layers, and the high-energy covalent bond can resist long-term corrosion of electrolyte. The non-polar molecular chain of the modified PP layer has poor compatibility with electrolyte, and there is no risk of swelling deformation. The three work together to ensure that the bonding structure between the layers is not damaged in the high-temperature electrolyte environment, effectively avoiding the interlayer failure caused by the penetration of electrolyte, and meeting the stringent requirements of long-term stable operation of high-energy density lithium batteries.

[0049] 4.The application uses the multi-protection design of "fluorocarbon chain barrier + dense bonding layer + hybrid network", and H2S and other corrosive gases cannot penetrate to the surface of the aluminum foil. The hydrophobic and oleophobic properties of the fluorocarbon chain hinder the adhesion and penetration of corrosive gases, and the Si-O-Al bond tightly wraps the aluminum foil to form a gapless protection, and the hybrid network further blocks the diffusion path, avoiding corrosion and failure of the aluminum foil, and ensuring the long-term stability of the material barrier performance, and adapting to various battery use scenarios under complex working conditions.

[0050] 5.The material of the application presents a gradient mechanical structure of "rigid puncture resistance of nylon layer → rigid and flexible balance of A / B layer → aluminum foil support → flexible heat sealing of PP layer", and the deformation coordination of each layer is excellent. The flexible segment of PBT in the nylon blend layer, the flexible fluorocarbon chain and the rigid silicone of the A / B layer, and the heat sealing adaptability of the PP layer make the material have no stress concentration during the deep drawing process, and can smoothly realize 13mm deep drawing without cracking, delamination or wrinkling, fully matching the industrial packaging process of soft-pack lithium batteries. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 The figure is a structural schematic diagram of a high-barrier lithium battery aluminum-plastic soft film material in the application.

[0052] Among them, 1: fluorine-containing grafted modified nylon blend layer, 2: composite barrier A layer, 3: chemically activated aluminum foil layer, 4: composite barrier B layer, 5: modified PP layer. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical scheme and advantages of the application more clear and obvious, the application will be further described in detail in combination with specific examples.

[0054] Example 1: A specific preparation method of a high-barrier lithium battery aluminum-plastic soft film material, comprising the following steps:

[0055] (1) 1 kg of nylon 66, 300 g of polybutylene terephthalate, 30 g of glycidyl methacrylate and 60 g of 2H, 2H, 3H, 3H-perfluoroundecanoic acid are dried and water is removed, then added to a high-speed mixer, 10 g of dicumyl peroxide and 10 g of antioxidant 1010 are added, stirred at room temperature for 10 min until mixed uniformly, and then put into a twin-screw extruder, set the temperature of zone 1 to 220°C, the temperature of zone 2 to 2440°C, the temperature of zone 3 to 250°C, the temperature of the die head to 250°C, the screw speed to 100 r / min, melt extruded, cooled into a film by a casting roll, and a fluorine-containing grafted modified nylon blend layer is prepared;

[0056] (2) Under nitrogen protection, according to the molar ratio of γ-aminopropyl triethoxysilane, anhydrous potassium carbonate, 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride is 1:1.5:1, 100 g of γ-aminopropyl triethoxysilane and 93.51 g of anhydrous potassium carbonate are added to 800 g of anhydrous ethyl acetate, cooled to 0°C, 230.30 g of 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride is added under stirring, reacted for 30 min, the room temperature is recovered, and the stirring is continued for 1 h to obtain a graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride, filter to remove potassium carbonate, then add 50 g of 3-isocyanate propyl trimethoxysilane, stir for 10 min until mixed uniformly, then adjust the total content of γ-aminopropyl triethoxysilane, 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride graft and 3-isocyanate propyl trimethoxysilane in the system to 30 wt% by adding anhydrous ethyl acetate, to obtain a composite barrier A layer;

[0057] (3) The aluminum foil with a thickness of 10 μm is immersed in a 5 wt% NaOH solution, heated to 50°C, and oscillated for 1 min, then rinsed with deionized water until the pH is neutral, then immersed in a 3 wt% HNO3 solution, oscillated at room temperature for 30 s, then rinsed with deionized water until the pH is neutral, and dried to obtain a chemically activated aluminum foil layer;

[0058] (4) Under nitrogen protection, 100 g of γ-aminopropyl triethoxysilane and 72.04 g of anhydrous potassium carbonate were added to 800 g of anhydrous ethanol, cooled to 0°C, and 177.42 g of 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride was added under stirring, reacted for 30 min, and then the temperature was restored to room temperature and stirring was continued for 1 h to obtain a graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride. The potassium carbonate was removed by filtration, 1 mol / L dilute hydrochloric acid was added to adjust the pH to 3-4, and stirring was continued for 4 h. Then, the content of the graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride in the system was adjusted to 30 wt% by adding anhydrous ethanol to obtain a composite barrier B layer;

[0059] (5) After drying and removing water from 1 kg of homopolymer polypropylene powder, 20 g of maleic anhydride, 20 g of hydroxyethyl methacrylate, and 3 g of dicumyl peroxide were added to a high-speed mixer, stirred for 10 min until uniformly mixed, and then fed into a twin-screw extruder. The temperature of zone 1 was set to 140°C, the temperature of zone 2 was set to 160°C, the temperature of zone 3 was set to 170°C, the temperature of the die head was set to 170°C, the screw rotation speed was set to 200 r / min, and the film was obtained by melt extrusion and cooling on a casting roll to obtain a modified PP layer.

[0060] (6) The composite barrier A layer was coated on one side of the fluorine-containing grafted and modified nylon blend layer to form a wet film A with a thickness of 3 μm, which was immediately fed into a hot press roller group with a temperature of 160°C, a pressure of 0.3 MPa, and a roller speed of 3 m / min for 10 s. Then, a dilute hydrochloric acid solution with a pH of 3-4 was sprayed onto the side of the composite barrier A layer, with a spraying amount of 5 g / m 2 The chemical activation aluminum foil layer was placed on the other side of the composite barrier B layer, and a composite barrier B layer was coated on the other side of the chemical activation aluminum foil layer to form a wet film B with a thickness of 3 μm. The film was fed into a pre-solidification box for pre-solidification with a temperature of 80°C, a pressure of 0.1 MPa, and a time of 10 min. After pre-solidification, the modified PP layer was placed on the other side of the composite barrier B layer, and the five-layer composite film was formed by hot pressing in a hot press machine with a temperature of 180°C, a pressure of 0.5 MPa, and a time of 10 s. The five-layer composite film was vacuum dried, and then aged at room temperature and 50% environmental humidity for 48 h. After cutting and winding, a high-barrier lithium battery aluminum-plastic soft film material was obtained.

[0061] Example 2: A specific preparation method of a high-barrier lithium battery aluminum-plastic soft film material, including the following steps:

[0062] (1) 1 kg of nylon 66, 400 g of polybutylene terephthalate, 50 g of glycidyl methacrylate and 120 g of 2H, 2H, 3H, 3H-perfluoroundecanoic acid are dried and water is removed, then added to a high-speed mixer, 20 g of dicumyl peroxide and 20 g of antioxidant 1010 are added, stirred at room temperature for 15 min until mixed uniformly, then put into a twin-screw extruder, set the temperature of zone 1 to 230°C, the temperature of zone 2 to 245°C, the temperature of zone 3 to 255°C, the temperature of the die head to 260°C, the screw speed to 200 r / min, melt extruded, cooled into a film by a casting roll, and a fluorine-containing grafted modified nylon blend layer is prepared;

[0063] (2) Under nitrogen protection, according to the molar ratio of γ-aminopropyl triethoxysilane, anhydrous potassium carbonate, 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride is 1:1.8:1, 100 g of γ-aminopropyl triethoxysilane and 112.38 g of anhydrous potassium carbonate are added to 1 kg of anhydrous ethyl acetate, cooled to 0°C, 230.64 g of 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride is added under stirring, reacted for 45 min, the room temperature is recovered, and the stirring is continued for 1.5 h to obtain a graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride, filter to remove potassium carbonate, then add 70 g of 3-isocyanate propyl trimethoxysilane, stir for 20 min until mixed uniformly, then adjust the total content of γ-aminopropyl triethoxysilane, 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride graft and 3-isocyanate propyl trimethoxysilane in the system to 35 wt% by adding anhydrous ethyl acetate, and a composite barrier A layer is obtained;

[0064] (3) The aluminum foil with a thickness of 10 μm is immersed in a 5 wt% NaOH solution, heated to 55°C, and oscillated for 2 min, then rinsed with deionized water until the pH is neutral, then immersed in a 3 wt% HNO3 solution, oscillated at room temperature for 50 s, then rinsed with deionized water until the pH is neutral, and dried to obtain a chemically activated aluminum foil layer;

[0065] (4) Under nitrogen protection, 100 g of γ-aminopropyl triethoxysilane and 74.92 g of anhydrous potassium carbonate were added to 1 kg of anhydrous ethanol, cooled to 0°C, and 153.76 g of 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride was added under stirring for 45 min, and then the reaction was continued at room temperature for 1.5 h to obtain a graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride. The potassium carbonate was removed by filtration, and the pH was adjusted to 3-4 by adding dilute hydrochloric acid with a concentration of 1 mol / L. The stirring was continued for 5 h, and then the content of the graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride in the system was adjusted to 35 wt% by concentration under reduced pressure to obtain a composite barrier B layer;

[0066] (5) After drying and removing water from 1 kg of homopolymer polypropylene powder, 50 g of maleic anhydride, 50 g of hydroxyethyl methacrylate, and 5 g of dicumyl peroxide were added to a high-speed mixer and stirred for 15 min until they were uniformly mixed. Then they were put into a twin-screw extruder, and the temperature of the first zone was set to 150°C, the temperature of the second zone was set to 165°C, the temperature of the third zone was set to 175°C, the temperature of the die head was set to 180°C, the screw rotation speed was set to 250 r / min, and the film was obtained by melt extrusion and cooling on a casting roll to obtain a modified PP layer.

[0067] (6) The composite barrier A layer was coated on one side of the fluorine-containing grafted and modified nylon blend layer to form a wet film A with a thickness of 4 μm, which was immediately fed into a hot press roller group with a temperature of 165°C, a pressure of 0.4 MPa, and a roller speed of 5 m / min for 12 s. Then, a dilute hydrochloric acid solution with a pH of 3-4 was sprayed on the side of the composite barrier A layer, and the spraying amount was 8 g / m 2 After 15 min, the chemically activated aluminum foil layer was placed on it, and the composite barrier B layer was coated on the other side of the chemically activated aluminum foil layer to form a wet film B with a thickness of 5 μm, which was sent to a pre-solidification box for pre-solidification with a temperature of 85°C, a pressure of 0.2 MPa, and a time of 15 min. After pre-solidification, the modified PP layer was placed on the other side of the composite barrier B layer, and the five-layer composite film was obtained by hot pressing through a hot press with a temperature of 185°C, a pressure of 0.6 MPa, and a time of 20 s. Finally, the five-layer composite film was vacuum dried, and then aged at room temperature and 50% environmental humidity for 48 h. After cutting and winding, a high-barrier lithium battery aluminum-plastic soft film material was obtained.

[0068] Example 3: A specific preparation method of a high-barrier lithium battery aluminum-plastic soft film material, including the following steps:

[0069] (1) 1 kg of nylon 66, 500 g of polybutylene terephthalate, 70 g of glycidyl methacrylate and 150 g of 2H, 2H, 3H, 3H-perfluoroundecanoic acid are dried and water is removed, then added to a high-speed mixer, and then 50 g of dicumyl peroxide and 50 g of antioxidant 1010 are added, stirred at room temperature for 20 min until mixed uniformly, and then put into a twin-screw extruder, with the temperature of the first zone set to 240°C, the temperature of the second zone set to 250°C, the temperature of the third zone set to 260°C, the temperature of the die set to 270°C, and the screw speed set to 300 r / min, and then melt-extruded, cooled into a film by a casting roll, and a fluorine-containing grafted modified nylon blend layer is prepared;

[0070] (2) Under nitrogen protection, 100 g of γ-aminopropyl triethoxysilane and 124.87 g of anhydrous potassium carbonate are added to 1.2 kg of anhydrous ethyl acetate, cooled to 0°C, and then 230.64 g of 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride is added under stirring, reacted for 60 min, the room temperature is restored, and stirring is continued for 2 h to obtain a graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride, the potassium carbonate is removed by filtration, then 100 g of 3-isocyanate propyl trimethoxysilane is added, stirred for 30 min until mixed uniformly, and then the total content of the graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride and 3-isocyanate propyl trimethoxysilane in the system is adjusted to 40 wt% by reduced-pressure concentration to obtain a composite barrier A layer;

[0071] (3) An aluminum foil with a thickness of 10 μm is immersed in a 5 wt% NaOH solution, heated to 60°C, and oscillated for 3 min, then rinsed with deionized water until the pH is neutral, then immersed in a 3 wt% HNO3 solution, oscillated at room temperature for 60 s, then rinsed with deionized water until the pH is neutral, and dried to obtain a chemically activated aluminum foil layer;

[0072] (4) Under nitrogen protection, 100 g of γ-aminopropyl triethoxysilane and 73.35 g of anhydrous potassium carbonate were added to 1.2 kg of anhydrous ethanol, cooled to 0°C, and 135.67 g of 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride was added under stirring, reacted for 60 min, and then the temperature was restored to room temperature and stirring was continued for 2 h to obtain a graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride. The potassium carbonate was removed by filtration, 1 mol / L dilute hydrochloric acid was added to adjust the pH to 3-4, and stirring was continued for 6 h. Then the content of the graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride in the system was adjusted to 40 wt% by concentration under reduced pressure to obtain a composite barrier B layer;

[0073] (5) After drying and removing water from 1 kg of homopolypropylene powder, 70 g of maleic anhydride, 70 g of hydroxyethyl methacrylate, and 7 g of dicumyl peroxide were added to a high-speed mixer, stirred for 20 min until uniformly mixed, and then fed into a twin-screw extruder. The temperature of zone 1 was set to 160°C, the temperature of zone 2 was set to 170°C, the temperature of zone 3 was set to 180°C, the temperature of the die head was set to 190°C, the screw speed was set to 300 r / min, and the film was obtained by melt extrusion and cooled by a casting roll to obtain a modified PP layer.

[0074] (6) The composite barrier A layer was coated on one side of the fluorine-containing grafted and modified nylon blend layer to form a wet film A with a thickness of 5 μm, which was immediately fed into a hot press roller group with a temperature of 170°C, a pressure of 0.5 MPa, and a roller speed of 7 m / min for 15 s. Then, a dilute hydrochloric acid solution with a pH of 3-4 was sprayed onto the side of the composite barrier A layer, with a spraying amount of 10 g / m 2 The chemical activation aluminum foil layer was placed on the other side of the composite barrier B layer, and a composite barrier B layer was coated on the other side of the chemical activation aluminum foil layer to form a wet film B with a thickness of 7 μm. The film was fed into a pre-solidification box for pre-solidification with a temperature of 90°C, a pressure of 0.3 MPa, and a time of 20 min. After pre-solidification, the modified PP layer was placed on the other side of the composite barrier B layer, and a five-layer composite film was obtained by hot pressing with a temperature of 190°C, a pressure of 0.7 MPa, and a time of 30 s. Finally, the five-layer composite film was vacuum dried, aged for 48 h at room temperature and 50% environmental humidity, cut, and wound to obtain a high-barrier lithium battery aluminum-plastic soft film material.

[0075] Comparative Example 1: The difference between Comparative Example 1 and Example 3 is that 2H, 2H, 3H, 3H-perfluoroundecanoic acid is not added in step (1).

[0076] Comparative Example 2: The difference between Comparative Example 2 and Example 3 is that polybutylene terephthalate is not added in step (1).

[0077] Comparative Example 3: The difference between Comparative Example 3 and Example 3 is that 3-isocyanate propyl trimethoxysilane is not added in step (2).

[0078] Comparative Example 4: The difference between Comparative Example 4 and Example 3 is that step (3) is deleted, and the aluminum foil is directly used without being subjected to alkaline pickling.

[0079] Comparative Example 5: The difference between Comparative Example 5 and Example 3 is that γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H- perfluoroundecanoyl chloride are added in a molar ratio of 1:1 in step (4).

[0080] Comparative Example 6: The difference between Comparative Example 6 and Example 3 is that hydroxyethyl methacrylate is not added in step (5).

[0081] Comparative Example 7: The difference between Comparative Example 7 and Example 3 is that 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride is not added in steps (2) and (4).

[0082] Comparative Example 8: The difference between Comparative Example 8 and Example 3 is that 2H, 2H, 3H, 3H-perfluoroundecanoic acid is not added in step (1), and 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride is not added in steps (2) and (4).

[0083] Performance test:

[0084] 1. Thickness test: The aluminum-plastic flexible film materials prepared in Examples 1-3 and Comparative Examples 1-8 are cut into test samples with a size of 100 mm x 100 mm, and a high-precision film thickness tester with a precision of 0.1 μm is used for testing. When testing, a nine-square sampling method is used, and the overall thickness is measured at the center of the test sample and at eight evenly distributed points 10 mm from the edge. Each point is measured three times, and the average value is taken. The experimental results are shown in Table 1.

[0085] 2. Interlayer peeling strength test: The aluminum-plastic flexible film material prepared from Examples 1-3 and Comparative Examples 1-8 was cut into a sample of 100 mm x 100 mm size, and tested using a universal material testing machine. According to the GB / T 2791-1995 standard, for the three key bonding surfaces of "fluorine-containing grafted modified nylon blend layer-composite barrier A layer", "composite barrier A layer-chemically activated aluminum foil layer", and "composite barrier B layer-modified PP layer", the starting end of the sample was manually peeled off by 5 mm to form a free end. The free end and the fixed end were clamped in the upper and lower clamps of the testing machine, respectively. The peeling angle was set to 180°, and the tensile speed was 50 mm / min. After starting the equipment, the force value change during the peeling process was recorded in real time. Five groups of samples were tested in parallel for each bonding surface. The average value of the maximum and minimum values was taken as the peeling strength of the bonding surface. Finally, the average strength of the three bonding surfaces represented the overall interlayer bonding performance of the sample. The experimental results are shown in Table 1.

[0086] 3. Water vapor transmission rate test: The aluminum-plastic flexible film material prepared from Examples 1-3 and Comparative Examples 1-8 was cut into a circular sample of 70 mm in diameter and fixed on a moisture permeable cup. 50 g of anhydrous calcium chloride was placed in the moisture permeable cup and sealed to ensure that the sample and the moisture permeable cup were in contact without leakage. Then the moisture permeable cup was placed in a constant temperature and humidity chamber with a temperature of 40°C and a relative humidity of 90%. After initial weighing, the moisture permeable cup was taken out every 24 h, the surface condensate was absorbed with filter paper, and then accurately weighed. The test was continuously conducted for 7 days. The daily water vapor transmission rate per unit area was calculated by the formula (transmission amount / sample area x time). The experimental results are shown in Table 1.

[0087] 4. Electrolyte resistance test: The aluminum-plastic flexible film material prepared from Examples 1-3 and Comparative Examples 1-8 was cut into the same size and placed in the same amount of electrolyte to make sample bags of the same size. After being placed in an environment of 85°C for 10 days, the overall interlayer bonding performance of the sample was determined according to the method in the "interlayer peeling strength test", and the peeling strength retention rate was calculated. The experimental results are shown in Table 1.

[0088] 5. H2S corrosion rate test: To simulate the corrosive environment that may occur during battery use, the aluminum-plastic flexible film material prepared from Examples 1-3 and Comparative Examples 1-8 was cut into a 50 mm x 50 mm sample and sealed in a corrosion test box. The test conditions were set as follows: temperature 50°C, relative humidity 90%, H2S gas concentration 200 ppm. After 1000 h of continuous exposure, the sample was taken out, the surface corrosion products were washed with deionized water, and then dehydrated with anhydrous ethanol and dried to constant weight. The corrosion rate of the material was calculated by the formula (mass of sample before corrosion - mass of sample after corrosion) / sample area. The experimental results are shown in Table 1.

[0089] 6. Punch deep forming performance test: According to the forming requirements of lithium battery aluminum plastic film, a cupping tester was used for punch deep test. The aluminum plastic soft film material prepared from examples 1-3 and comparative examples 1-8 was cut into a 100mm x 100mm sample, which was fixed on the lower mold seat of the tester. The punch diameter was set to 15mm, and the punch deep speed was set to 5mm / s. The punch was uniformly pressed into the sample to a depth of 13mm, then the punch was unloaded and the sample was taken out. The surface was observed for wrinkles and cracks. The interlayer was checked for peeling with a magnifying glass. The experimental results are shown in Table 1.

[0090]

[0091] Performance analysis:

[0092] From the experimental data in Table 1, it can be seen that the comprehensive performance of the aluminum plastic soft film material prepared in examples 1-3 is significantly better than that of each comparative example, and the performance shows a gradient improvement, among which the comprehensive performance of example 3 is the best.

[0093] The peeling strength directly reflects the firmness of the interlayer bonding. Example 3 performs the best because it has the most complete and continuous covalent bond network. In the fluorine-containing grafted modified nylon blend layer, excess glycidyl methacrylate (GMA) ring-opening generates a large number of hydroxyl groups. In the composite barrier A layer, a sufficient amount of 3-isocyanate propyl trimethoxysilane (IPTS) isocyanate group reacts with the hydroxyl group of the nylon layer to form a firm urethane bond. At the same time, Si-O-Al covalent bonds are formed between the A layer and the chemically activated aluminum foil layer through the silicon hydroxyl group and the aluminum foil surface hydroxyl group. In the composite barrier B layer, an intentionally excessive amount of γ-aminopropyl triethoxysilane (KH550) ensures that sufficient free amino groups are retained after hydrolysis. These amino groups undergo imidization with the high grafting amount of maleic anhydride (MAH) in the modified PP layer during hot pressing to form strong chemical bonds. This set of chemical bonding system throughout makes example 3 have the strongest interlayer bonding force.

[0094] Excellent barrier property is derived from the triple synergy of "fluorocarbon chain hydrophobic barrier + dense aluminum foil + hybrid network". Example 3 introduces the highest content of perfluoroalkyl chain in the outer nylon and the inner and outer composite barrier layers (A / B layers), forming a bidirectional fluorine barrier that repairs both inside and outside, greatly increasing the difficulty of water vapor and corrosive media (such as H2S) penetration. At the same time, the fully activated aluminum foil itself is a nearly zero-permeation physical barrier layer, and the Si-O-Al / Si-O-Si hybrid network formed by the hydroxyl group on the surface and the silicon hydroxyl group in the A / B layer effectively seals the micro defects on the surface of the aluminum foil. The three synergies make example 3 have the most dense protection system.

[0095] Example 3: Highest electrolyte post-peeling strength retention rate: Firstly, the high grafting amount of MAH in the modified PP layer reacts with hydroxyethyl methacrylate (HEMA), MAH provides reaction sites with amino groups in the B layer, and the hydroxyl group of HEMA enhances the polarity of the PP layer and assists in forming hydrogen bonds, making the PP layer itself more resistant to swelling; secondly, the sufficient free amino groups in the composite barrier B layer have the most sufficient imidization reaction with the MAH in the PP layer, forming chemical bonds that can effectively resist the penetration and destruction of electrolyte. Therefore, after electrolyte immersion, its interlayer bonding force loss is the smallest.

[0096] Good deep drawability requires not only firm bonding between layers of materials, but also a gradient mechanical structure that combines rigidity and flexibility. In Example 3, the blending ratio of nylon and PBT in the outer layer is moderate, providing the necessary rigidity to prevent puncture; the aluminum foil in the middle layer provides support and transition with the A / B layers; the inner layer of modified PP provides good flexibility. Most importantly, as mentioned earlier, its impregnable interlayer chemical bonding network ensures that during deep deformation, each layer can deform synchronously without peeling or cracking, achieving "strong bonding and synchronous deformation".

[0097] Comparative Example 1: The perfluoroundecanoic acid graft in the outer layer of nylon is missing. This causes the hydrophobic fluorocarbon barrier in the outermost layer of the material to fail, allowing water vapor and corrosive gases to directly contact and penetrate the outer layer, resulting in a significant decrease in water vapor barrier and corrosion resistance, and the appearance also appears to be curled due to moisture absorption or corrosion.

[0098] Comparative Example 2: The blending of polybutylene terephthalate (PBT) is missing. Although nylon 66 has high strength, it has a high water absorption rate. When used alone, the outer layer is more prone to moisture absorption and swelling in a high-humidity environment, affecting the dimensional stability and barrier properties, leading to an increase in water vapor transmission rate and an increased risk of wrinkles during deep drawing due to uneven local plastic deformation.

[0099] Comparative Example 3: The 3-isocyanate propyl trimethoxysilane (IPTS) in the composite barrier A layer is missing. This prevents the formation of strong urethane bonds between the nylon layer and the A layer, relying only on physical interaction or weak hydrogen bonds, resulting in extremely weak interfacial bonding at this location. During peeling tests or deep deformation, the nylon layer and the A layer will peel off prematurely.

[0100] Comparative Example 4: The aluminum foil is not subjected to alkaline and acid washing activation treatment. Its surface lacks sufficient active hydroxyl groups, preventing the formation of sufficient Si-O-Al covalent bonds between the composite barrier A and B layers. This makes the bonding between the aluminum foil and the upper and lower barrier layers mainly rely on physical adhesion, resulting in weak bonding and easy interlayer separation under stress, which also leads to defects in barrier performance.

[0101] Comparative Example 5: In the preparation of the composite barrier B layer, γ-aminopropyltriethoxysilane (KH550) was reacted with perfluoroundecanoyl chloride at a 1:1 molar ratio, without KH550 excess. This resulted in almost no free active amino groups remaining after hydrolysis of the B layer, which could not fully react with the maleic anhydride of the modified PP layer to form imide. Therefore, the chemical bonding between the PP layer and the B layer was severely insufficient, and in the electrolyte immersion test, this interface became the weakest link, with a significant decrease in bond retention.

[0102] Comparative Example 6: No hydroxyethyl methacrylate (HEMA) was added in the preparation of the modified PP layer. Although MAH provided the main reaction site for bonding with the B layer, the absence of HEMA reduced the polarity, hydrophilicity, and compatibility adjustment ability of the PP layer with the non-polar PP matrix. This can result in suboptimal internal structure of the PP layer or secondary interactions (such as hydrogen bonds) with the B layer, leading to slightly inferior interface stability in long-term or harsh environments (such as electrolyte immersion), as evidenced by a slight decrease in peel strength retention.

[0103] Comparative Example 7: No perfluoroundecanoyl chloride was introduced for fluorinated modification in both the composite barrier A layer and the B layer. This caused the material to lose the critical fluorocarbon chain hydrophobic barrier on both the inside and outside, relying solely on the aluminum foil for physical barrier. Corrosive media and water vapor can more easily penetrate and attack the interface and the aluminum foil itself, resulting in significantly poorer corrosion resistance and barrier properties.

[0104] Comparative Example 8: This is the most comprehensive defect comparison, with no fluorinated components introduced in the outer nylon and the inner and outer barrier layers. The material simultaneously loses the hydrophobic protection of the fluorocarbon chain and the integrity of the interface bonding that may be affected by component changes. Its barrier properties, corrosion resistance, and interlayer bonding force are the worst among all samples, showing comprehensive performance failure in the test.

[0105] The above description is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any skilled person in the art can make equivalent replacements or changes to the technical solutions and inventive concepts of the present application within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A preparation method of high-barrier lithium battery aluminum-plastic flexible film material, characterized in that, Comprising the following steps: (1) After drying and removing water from nylon 66, polybutylene terephthalate, glycidyl methacrylate and 2H, 2H, 3H, 3H- perfluoroundecanoic acid, add it into a high-speed mixer, then add dicumyl peroxide and antioxidant 1010, stir for 10-20 min at room temperature until mixed evenly, put it into a twin-screw extruder, melt extrude, cool into a film by a casting roll, and prepare a fluorine-containing grafted modified nylon blend layer; (2) Under nitrogen protection, add γ-aminopropyl triethoxysilane and anhydrous potassium carbonate into anhydrous ethyl acetate, cool to 0℃, and then add 2H, 2H, 3H, 3H- perfluoroundecanoyl chloride under stirring, react for 30-60 min, restore room temperature, and continue stirring for 1-2 h to obtain the graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H- perfluoroundecanoyl chloride, filter out potassium carbonate, then add 3-isocyanate propyl trimethoxysilane, stir for 10-30 min until mixed evenly, and then adjust the total content of the graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H- perfluoroundecanoyl chloride and 3-isocyanate propyl trimethoxysilane in the system to 30wt-40wt% by adding solvent or reducing pressure concentration to obtain the material of composite barrier A layer; (3) Soak aluminum foil into 5wt% NaOH solution, heat to 50-60℃, oscillate for 1-3 min, then rinse with deionized water until pH is neutral, then soak into 3wt% HNO3 solution, oscillate for 30-60 s at room temperature, then rinse with deionized water until pH is neutral, dry to obtain a chemically activated aluminum foil layer; (4) Under nitrogen protection, add γ-aminopropyl triethoxysilane and anhydrous potassium carbonate into anhydrous ethanol, cool to 0℃, and then add 2H, 2H, 3H, 3H- perfluoroundecanoyl chloride under stirring, react for 30-60 min, restore room temperature, and continue stirring for 1-2 h to obtain the graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H- perfluoroundecanoyl chloride, filter out potassium carbonate, add dilute hydrochloric acid to adjust pH to 3-4, continue stirring for 4-6 h, then adjust the content of the graft of γ-aminopropyl triethoxysilane and 2H, 2H, 3H, 3H- perfluoroundecanoyl chloride in the system to 30wt-40wt% by adding solvent or reducing pressure concentration to obtain the material of composite barrier B layer; (5) After drying and removing water from homopolymer polypropylene powder, add maleic anhydride, hydroxyethyl methacrylate and dicumyl peroxide into a high-speed mixer, stir for 10-20 min until mixed evenly, then put it into a twin-screw extruder, melt extrude, cool into a film by a casting roll, and obtain a modified PP layer; (6) The material of the composite barrier A layer is coated on one side of the fluorine-grafted modified nylon blend layer to form a wet film A. It is immediately put into the hot press roller group and hot-pressed for 10-15s to obtain the composite barrier A layer. Then, dilute hydrochloric acid solution is sprayed on the side where the composite barrier A layer is located and placed horizontally for 10-20min. Then, the chemically activated aluminum foil layer is placed on it, and the material of the composite barrier B layer is coated on the other side of the chemically activated aluminum foil layer to form a wet film B. It is sent into the pre-curing box for pre-curing. After the pre-curing is completed, the composite barrier B layer is obtained. The modified PP layer is placed on the other side of the composite barrier B layer and hot-pressed to form a composite film by a hot press to obtain a five-layer composite film. Finally, the five-layer composite film is vacuum dried and cured at room temperature and 50% ambient humidity for 48h. After cutting and winding, the high barrier lithium battery aluminum-plastic soft film material is obtained. In (1), nylon 66, polybutylene terephthalate, glycidyl methacrylate, 2H,2H,3H,3H-perfluoroundecanoic acid, dicumyl peroxide and antioxidant 1010 are present in a weight ratio of 1:(0.3-0.5):(0.03-0.07):(0.06-0.15):(0.01-0.03):(0.01-0.05); In (4), the molar ratio of γ-aminopropyltriethoxysilane, anhydrous potassium carbonate, and 2H,2H,3H,3H-perfluoroundecanoyl chloride is (1.3-1.7):(1.5-2):

1.

2. The method for preparing the high-barrier lithium battery aluminum-plastic soft film material according to claim 1, characterized in that, In the twin-screw extruder described in (1), the temperature in zone one is 220-240℃, the temperature in zone two is 240-250℃, the temperature in zone three is 250-260℃, the temperature at the die head is 250-270℃, and the screw speed is 100-300r / min.

3. The method for preparing the high-barrier lithium battery aluminum-plastic soft film material according to claim 1, characterized in that, In (2), the molar ratio of γ-aminopropyltriethoxysilane, anhydrous potassium carbonate, and 2H,2H,3H,3H-perfluoroundecanoyl chloride is 1:(1.5-2):1; the weight ratio of γ-aminopropyltriethoxysilane, anhydrous ethyl acetate, and 3-isocyanate-propyltrimethoxysilane is 1:(8-12):(0.5-1).

4. The method for preparing the high-barrier lithium battery aluminum-plastic soft film material according to claim 1, characterized in that, The thickness of the aluminum foil in (3) is 10 μm.

5. The method for preparing the high-barrier lithium battery aluminum-plastic soft film material according to claim 1, characterized in that, In (4), the weight ratio of γ-aminopropyltriethoxysilane and anhydrous ethanol is 1:(8-12); the concentration of dilute hydrochloric acid is 1 mol / L.

6. The method for preparing the high-barrier lithium battery aluminum-plastic soft film material according to claim 1, characterized in that, In (5), the homopolymer polypropylene powder, maleic anhydride, hydroxyethyl methacrylate and diisopropylbenzene peroxide are in a weight ratio of 1:(0.02-0.07):(0.02-0.07):(0.003-0.007); the melt index of the homopolymer polypropylene powder is 3 g / 10 min.

7. The method for preparing the high-barrier lithium battery aluminum-plastic flexible film material according to claim 1, characterized in that, In the twin-screw extruder described in (5), the temperature in zone one is 140-160℃, the temperature in zone two is 160-170℃, the temperature in zone three is 170-180℃, the temperature at the die head is 170-190℃, and the screw speed is 200-300r / min.

8. The method for preparing the high-barrier lithium battery aluminum-plastic flexible film material according to claim 1, characterized in that, The thickness of the wet film A in the step (6) is 3-5 μm, the parameters of the hot-press roller group are temperature 160-170 ℃, pressure 0.3-0.5 MPa, and roller speed 3-7 m / min; the pH of the dilute hydrochloric acid solution is 3-4, and the spraying amount is 5-10 g / m 2 ; the thickness of the wet film B is 3-7 μm, the pre-solidification conditions are temperature 80-90 ℃, pressure 0.1-0.3 MPa, and time 10-20 min; and the hot-press parameters of the hot press are temperature 180-190 ℃, pressure 0.5-0.7 MPa, and time 10-30 s.

9. A high-barrier lithium battery AL-PLF material, which is prepared by the method of any one of claims 1-8, characterized in that, From the outside to the inside, it includes a fluorine-grafted modified nylon blend layer, a composite barrier A layer, a chemically activated aluminum foil layer, a composite barrier B layer, and a modified PP layer. The fluorine-containing graft-modified nylon blend layer is mainly composed of a nylon 66 and polybutylene terephthalate blend, grafts 2H, 2H, 3H, 3H-perfluoroundecanoic acid through glycidyl methacrylate as a graft bridge; The composite barrier A layer is a blend of gamma-aminopropyl triethoxysilane, a graft of 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride and 3-isocyanate propyl trimethoxysilane; The chemically activated aluminum foil layer is obtained by alkali washing and acid washing of an aluminum foil; The composite barrier B layer is a mixture of gamma-aminopropyl triethoxysilane, a graft of 2H, 2H, 3H, 3H-perfluoroundecanoyl chloride after hydrolysis; The modified PP layer is mainly composed of a homopolymer PP, grafts maleic anhydride and hydroxyethyl methacrylate.

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