Aluminum-plastic film with enhanced interface bonding strength and preparation method thereof

Abstract

The present invention discloses an aluminum-plastic film with enhanced interfacial bonding strength and a preparation method thereof, relating to the field of lithium battery technology. The preparation method comprises: depositing a carbon-based film layer containing amino functional groups on the surface of a pretreated aluminum foil by chemical vapor deposition; adding 1-3 wt% graphene oxide (GO) and 0.5-1 wt% photoinitiator benzophenone to a polyurethane prepolymer containing disulfide bonds by solution mixing, and coating the film on the carbon-based film; and applying a photosensitive initiator to the film using a wavelength of 365 nm and an intensity of 50-100 mW / cm 2 The film is then cured by UV irradiation for 5-10 minutes. Finally, a 30-50μm thick polypropylene outer layer is applied and hot-pressed to complete the process. The resulting aluminum-plastic film significantly enhances interfacial bonding and electrolyte penetration resistance through Al-N bonds, GO modification, and disulfide bond self-healing mechanisms, effectively suppressing microcrack propagation and meeting the high durability requirements of lithium battery packaging.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to an aluminum-plastic film with enhanced interface bonding strength and a preparation method thereof. Background Art

[0002] Aluminum-plastic film, a layered material composed of aluminum foil and polymer film, has become a key material for lithium-ion battery packaging due to its excellent moisture and gas barrier properties and plasticity. It is also widely used in industries such as food packaging and pharmaceutical packaging. With the lithium battery industry's growing demand for high safety, long life, and high energy density, research and development in aluminum-plastic film technology has increasingly focused on improving interfacial bonding, corrosion resistance, and heat-sealing properties. Currently, aluminum-plastic film preparation processes primarily involve dry lamination and wet lamination, achieving interlayer bonding by introducing adhesives (such as polyurethane or epoxy resin) between the aluminum foil and the polymer layer (such as nylon, polypropylene, or polyester). To further enhance interfacial properties, surface treatments such as chemical etching or plasma modification are commonly used to increase the roughness and active sites on the aluminum foil surface, thereby enhancing mechanical and chemical bonding. Additionally, some studies have explored doping the interfacial layer with nanoparticles (such as silica or alumina) or functionalized polymers to improve interfacial strength and durability. These technological advances have promoted the optimization of the initial performance of aluminum-plastic film. However, its long-term stability in complex usage environments still requires further breakthroughs, especially its performance in lithium battery electrolyte corrosion scenarios has attracted much attention.

[0003] Although existing technologies provide multiple paths for enhancing the interface of aluminum-plastic film, their shortcomings in specific microcrack application scenarios are still significant, especially in terms of the generation of interface microcracks and the risk of long-term failure after electrolyte penetration. Taking lithium battery packaging as an example, when the aluminum-plastic film is in contact with the electrolyte for a long time, the electrolyte molecules penetrate through the interface defects and cause local stress concentration. The difference in thermal expansion coefficients between the aluminum layer and the plastic layer and the depolymerization of the chemical bonds in the adhesive layer accelerate the initiation and expansion of stress. This problem directly threatens the integrity of the packaging structure and the service life of the battery. Although existing adhesives or surface modification technologies can improve the initial interface strength to a certain extent, their resistance to chemical corrosion is limited and it is difficult to effectively resist interface degradation caused by the electrolyte. In addition, traditional mechanical interlocking or filler reinforcement methods mostly focus on improving static performance, and lack dynamic inhibition or damage evolution control mechanisms after microcrack generation, resulting in a significant decrease in the stability of the interface under cyclic stress or chemical action. Summary of the Invention

[0004] When the aluminum-plastic film is in contact with the electrolyte for a long time, the electrolyte molecules penetrate through the interface defects and cause local stress concentration. The difference in thermal expansion coefficients between the aluminum layer and the plastic layer and the depolymerization of the chemical bonds in the adhesive layer accelerate the initiation and expansion of stress. This problem directly threatens the integrity of the packaging structure and the service life of the battery.

[0005] The present application provides a method for preparing an aluminum-plastic film with enhanced interfacial bonding strength, comprising the following technical steps: step S1. depositing a carbon-based film layer containing amino functional groups on a pretreated aluminum foil surface by chemical vapor deposition; step S2. adding 1wt% to 3wt% of graphene oxide to a polyurethane prepolymer containing disulfide bonds by a solution mixing method, adding 0.5-1wt% of a photosensitive initiator, and coating the mixture on the carbon-based film layer; step S3. irradiating the coated composite structure with ultraviolet light; and step S4. attaching a polymer outer layer to the cured polyurethane layer, and completing the preparation of the aluminum-plastic film by a hot pressing process.

[0006] It should be noted that in step S1, a carbon-based film containing amino functional groups is deposited on the surface of pretreated aluminum foil via chemical vapor deposition (CVD). The amino groups (-NH2) form Al-N covalent bonds with the hydroxyl groups on the aluminum surface, establishing a strong chemical bridge. Simultaneously, the film's nanoporous structure further enhances interfacial stability through mechanical intercalation, providing a solid foundation for subsequent interlayer bonding. In step S2, 1-3 wt% graphene oxide (GO) is incorporated into a polyurethane prepolymer containing disulfide bonds, along with 0.5-1 wt% photoinitiator. The film is then coated onto the surface of the carbon-based film via a solution mixing method. The carboxyl, hydroxyl, and epoxy groups of GO react with the amino groups of the carbon-based film, forming a chemically and physically synergistic interfacial transition layer that ensures close contact between the coating and the film. The photoinitiator also reserves reactive activity for subsequent curing. In step S3, free radical polymerization is initiated by UV irradiation. The hydroxyl or ester groups in the polyurethane cure with the amino groups of the carbon-based film to form a dense network, significantly enhancing interfacial bonding and optimizing interlayer stability. In step S4, the outer polymer layer is fused to the polyurethane layer through a hot-pressing process. The amino groups on the carbon-based film surface, activated by high temperature, enhance their nucleophilicity. These react with the carboxyl, hydroxyl, and epoxy groups on the GO surface, strengthening the chemical bonding at the interface layer and also causing partial reduction of the GO. When electrolyte penetration triggers microcracks in the polyurethane layer, the modified GO in the interface layer, retaining some hydrophilic functional groups, can effectively capture trace amounts of water or polar solvent molecules, creating a localized high-humidity microenvironment. This microenvironment reduces the activation energy of the dynamic exchange of disulfide bonds in the polyurethane layer, accelerating their breakage and recombination under stress or humidity stimulation, and promoting the self-healing of microcracks.

[0007] As a preferred technical solution for a method of preparing an aluminum-plastic film with enhanced interfacial bonding strength, in step S1, the deposition conditions are a temperature of 150-200° C. and a reaction time of 30-60 minutes.

[0008] It should be noted that under this deposition condition, a uniform carbon-based film is formed to enhance the interfacial bonding strength.

[0009] As a preferred technical solution for a method of preparing an aluminum-plastic film with enhanced interfacial bonding strength, in step S2, the thickness of the carbon-based film layer is controlled to be 10-30 μm.

[0010] It should be noted that a moderate thickness not only improves the interfacial bonding strength, resists electrolyte penetration, promotes self-repair efficiency, effectively inhibits the expansion of microcracks, but also improves the long-term durability and failure resistance of the aluminum-plastic film in an electrolyte corrosion environment.

[0011] As a preferred technical solution for a method for preparing an aluminum-plastic film with enhanced interfacial bonding strength, in step S2, the preparation process of a polyurethane prepolymer containing disulfide bonds includes: mixing 2,2'-dithiodiethanol and isophorone diisocyanate in a molar ratio of 1:1.2, adding 0.1wt% of dibutyltin dilaurate catalyst, and reacting at 80°C for 4 hours under nitrogen protection to obtain a polyurethane prepolymer containing disulfide bonds with a molecular weight of 50,000-100,000.

[0012] It should be noted that 2,2'-dithiodiethanol, as a soft-segment monomer, possesses dynamically reversible disulfide bonds (-SS-) within its molecular chain, while the terminal hydroxyl groups (-OH) are highly reactive. IPDI, as a hard-segment monomer, possesses two isocyanate groups (-NCO) that react with hydroxyl groups to form carbamate bonds (-NHCOO-). A slight excess of IPDI in a 1:1.2 molar ratio ensures sufficient isocyanate groups in the reaction system, promoting chain growth without excessive cross-linking, while also avoiding the formation of urea or isocyanurate bonds as side reactions. The addition of 0.1wt% dibutyltin dilaurate catalyst significantly reduces the activation energy for the reaction between hydroxyl groups and isocyanate groups, accelerating carbamate bond formation through coordination catalysis, enabling the reaction to proceed efficiently at a mild temperature of 80°C. A nitrogen atmosphere effectively eliminates interference from moisture and oxygen, preventing the formation of amine byproducts from the reaction of isocyanate with water, thereby ensuring the purity of the polymer structure and the integrity of the disulfide bonds. After a four-hour reaction, 2,2'-dithiodiethanol and IPDI gradually polymerize to form linear or slightly branched polyurethane prepolymers with a molecular weight of 50,000-100,000. Disulfide bonds are evenly distributed throughout the soft segment, laying the foundation for subsequent self-healing properties. In aluminum-plastic film applications, the dynamic reversibility of disulfide bonds allows them to break and recombine through stress or humidity stimulation when microcracks are induced by electrolyte penetration, repairing microscopic damage and enhancing interfacial durability and microcrack resistance.

[0013] As a preferred technical solution for a method for preparing an aluminum-plastic film with enhanced interfacial bonding strength, the molecular weight of the 2,2'-dithiodiethanol is 2000-4000.

[0014] It should be noted that this molecular weight range ensures good fluidity and dispersibility of 2,2'-dithiodiethanol in the reaction system, reduces the viscosity of the system, facilitates the uniform reaction of IPDI at a molar ratio of 1:1.2, and avoids excessive cross-linking caused by low molecular weight diols (<2000) or chain entanglement and incomplete reaction caused by high molecular weight diols (>4000).

[0015] As a preferred technical solution for a method for preparing an aluminum-plastic film with enhanced interfacial bonding strength, the photoinitiator is benzophenone.

[0016] It should be noted that the photosensitive initiator benzophenone initiates free radical polymerization through light excitation during the UV curing of the aluminum-plastic film, thereby enhancing the interfacial bonding strength.

[0017] As a preferred technical solution for a method of preparing an aluminum-plastic film with enhanced interfacial bonding strength, in step S1, the pretreatment step includes: performing low-temperature plasma treatment on an aluminum foil with a thickness of 20-50 μm, with a power of 100-200 W, an argon and oxygen mixed atmosphere, and a treatment time of 2-5 minutes.

[0018] It should be noted that the above process significantly improves the chemical activity and mechanical intercalation ability of the aluminum foil surface, providing a solid foundation for the subsequent Al-N bond formation of the carbon-based film and the combination of the polyurethane layer.

[0019] As a preferred technical solution for a method of preparing an aluminum-plastic film with enhanced interfacial bonding strength, in step S4, the wavelength of the ultraviolet light is 365 nm, the intensity is 50-100 mW / cm2, and the irradiation time is 5-10 minutes.

[0020] It should be noted that moderate light intensity and time ensure uniform curing, retain the activity of disulfide bonds, promote self-repair efficiency, and at the same time extend the electrolyte penetration path, reduce the risk of microcracks, and improve the durability and failure resistance of the packaging structure.

[0021] As a preferred technical solution for a method of preparing an aluminum-plastic film with enhanced interfacial bonding strength, in step S4, the polymer outer layer is polypropylene with a thickness of 30-50 μm, the hot pressing process temperature is 120-150° C., the pressure is 0.5-1.0 MPa, and the time is 10-20 seconds.

[0022] It should be noted that the above process can achieve close integration with the polyurethane layer, thereby enhancing the mechanical toughness and barrier properties of the aluminum-plastic film.

[0023] The aluminum-plastic film of this invention significantly improves interfacial bonding and electrolyte penetration resistance through the synergistic effect of a carbon-based film containing amino functional groups, GO modification, and disulfide bond self-repair. Experimental data show that the peel strength reaches 11.8-12.5 N / cm, far exceeding the target value of 10 N / cm, and the leakage is only 0.3-0.4 mg / cm 2 , below the target value of 0.5 mg / cm 2 , demonstrating excellent interfacial stability and barrier properties. The Al-N covalent bonds and nanopore intercalation of the carbon-based film enhance interlayer bonding, while the doping and heat-pressure-induced modification of GO optimize interfacial chemical bonding. The dynamic reversibility of the disulfide bonds enables efficient self-repair when microcracks caused by electrolyte corrosion occur, extending the permeation path and effectively inhibiting crack propagation. This significantly improves the durability and failure resistance of the aluminum-plastic film in lithium battery packaging, meeting the requirements of high safety and long life. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The infrared spectrum of the disulfide bond-containing polyurethane prepolymer prepared in Preparation Example 1. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it constitute a separate or selective embodiment that is mutually exclusive with other embodiments.

[0028] Preparation Example

[0029] Preparation Example 1

[0030] The preparation process of the polyurethane prepolymer containing disulfide bonds includes: mixing 2,2'-dithiodiethanol (molecular weight of 4000) and isophorone diisocyanate in a molar ratio of 1:1.2, adding 0.1wt% of dibutyltin dilaurate catalyst, and reacting at 80°C for 4 hours under nitrogen protection to obtain a polyurethane prepolymer containing disulfide bonds with a molecular weight of 50,000-100,000.

[0031] Preparation Example 2

[0032] The preparation process of the polyurethane prepolymer containing disulfide bonds includes: mixing 2,2'-dithiodiethanol (molecular weight of 2000) and isophorone diisocyanate in a molar ratio of 1:1.2, adding 0.1wt% of dibutyltin dilaurate catalyst, and reacting at 80°C for 4 hours under nitrogen protection to obtain a polyurethane prepolymer containing disulfide bonds with a molecular weight of 50,000-100,000.

[0033] Preparation Example 3

[0034] The preparation process of the polyurethane prepolymer containing disulfide bonds includes: mixing 2,2'-dithiodiethanol (molecular weight of 3000) and isophorone diisocyanate in a molar ratio of 1:1.2, adding 0.1wt% of dibutyltin dilaurate catalyst, and reacting at 80°C for 4 hours under nitrogen protection to obtain a polyurethane prepolymer containing disulfide bonds with a molecular weight of 50,000-100,000.

[0035] Example

[0036] Example 1

[0037] Example 1 A method for preparing an aluminum-plastic film with enhanced interfacial bonding strength comprises the following technical steps:

[0038] Step 1. A 20 μm thick aluminum foil was treated with a low-temperature plasma at a power of 100 W in an argon and oxygen mixed atmosphere for 5 minutes.

[0039] Step 2. On the surface of the pretreated aluminum foil, a carbon-based film layer containing amino functional groups is deposited by chemical vapor deposition. The thickness of the carbon-based film layer is controlled at 10 μm. The deposition conditions are a temperature of 150 ° C and a reaction time of 60 minutes.

[0040] Step 3. 3 wt % of graphene oxide was added to the disulfide bond-containing polyurethane prepolymer (Preparation Example 1) by a solution mixing method, 0.5 wt % of benzophenone was added, and the mixture was coated on the carbon-based film layer;

[0041] Step 4. Irradiate the coated composite structure with UV light at a wavelength of 365 nm and an intensity of 100 mW / cm 2 , irradiation time 5 minutes;

[0042] Step 5. Attach a polymer outer layer to the cured polyurethane layer and complete the preparation of the aluminum-plastic film through a hot pressing process. The polymer outer layer is polypropylene with a thickness of 30 μm. The hot pressing process is carried out at a temperature of 150° C., a pressure of 0.5 MPa, and a time of 20 seconds.

[0043] Example 2

[0044] Example 2 A method for preparing an aluminum-plastic film with enhanced interfacial bonding strength comprises the following technical steps:

[0045] Step 1. A 50 μm thick aluminum foil was treated with a low-temperature plasma at a power of 200 W in an argon and oxygen mixed atmosphere for 2 minutes.

[0046] Step 2. On the surface of the pretreated aluminum foil, a carbon-based film layer containing amino functional groups is deposited by chemical vapor deposition. The thickness of the carbon-based film layer is controlled at 30 μm. The deposition conditions are a temperature of 200 ° C and a reaction time of 30 minutes.

[0047] Step 3. 1 wt% of graphene oxide is added to the disulfide bond-containing polyurethane prepolymer (Preparation Example 2) by a solution mixing method, 1 wt% of benzophenone is added, and the mixture is coated on the carbon-based film layer;

[0048] Step 4. Irradiate the coated composite structure with UV light at a wavelength of 365 nm and an intensity of 50 mW / cm 2 , irradiation time 10 minutes;

[0049] Step 5. Attach a polymer outer layer to the cured polyurethane layer and complete the preparation of the aluminum-plastic film through a hot pressing process. The polymer outer layer is polypropylene with a thickness of 50 μm. The hot pressing process temperature is 120° C., the pressure is 1.0 MPa, and the time is 10 seconds.

[0050] Example 3

[0051] Example 3 A method for preparing an aluminum-plastic film with enhanced interfacial bonding strength comprises the following technical steps:

[0052] Step 1. A 30 μm thick aluminum foil was treated with a low-temperature plasma at a power of 150 W in an argon and oxygen mixed atmosphere for 3 minutes.

[0053] Step 2. On the surface of the pretreated aluminum foil, a carbon-based film layer containing amino functional groups is deposited by chemical vapor deposition. The thickness of the carbon-based film layer is controlled at 20 μm. The deposition conditions are a temperature of 200 ° C and a reaction time of 50 minutes.

[0054] Step 3. 2 wt% of graphene oxide was added to the disulfide bond-containing polyurethane prepolymer (Preparation Example 3) by a solution mixing method, 0.8 wt% of benzophenone was added, and the mixture was coated on the carbon-based film layer;

[0055] Step 4. Irradiate the coated composite structure with UV light at a wavelength of 365 nm and an intensity of 80 mW / cm 2 , irradiation time 10 minutes;

[0056] Step 5. Attach a polymer outer layer to the cured polyurethane layer and complete the preparation of the aluminum-plastic film through a hot pressing process. The polymer outer layer is polypropylene with a thickness of 40 μm. The hot pressing process is carried out at a temperature of 120° C., a pressure of 0.8 MPa, and a time of 10 seconds.

[0057] Example 4

[0058] Example 4 A method for preparing an aluminum-plastic film with enhanced interfacial bonding strength comprises the following technical steps:

[0059] Step 1. A 50 μm thick aluminum foil was treated with a low-temperature plasma at a power of 200 W in an argon and oxygen mixed atmosphere for 3 minutes.

[0060] Step 2. On the surface of the pretreated aluminum foil, a carbon-based film layer containing amino functional groups is deposited by chemical vapor deposition. The thickness of the carbon-based film layer is controlled at 10 μm. The deposition conditions are a temperature of 150 ° C and a reaction time of 50 minutes.

[0061] Step 3. 2 wt% of graphene oxide was added to the disulfide bond-containing polyurethane prepolymer (Preparation Example 2) by a solution mixing method, 0.8 wt% of benzophenone was added, and the mixture was coated on the carbon-based film layer;

[0062] Step 4. Irradiate the coated composite structure with UV light at a wavelength of 365 nm and an intensity of 80 mW / cm 2 , irradiation time 10 minutes;

[0063] Step 5. Attach a polymer outer layer to the cured polyurethane layer and complete the preparation of the aluminum-plastic film through a hot pressing process. The polymer outer layer is polypropylene with a thickness of 30 μm. The hot pressing process is carried out at a temperature of 120° C., a pressure of 0.8 MPa, and a time of 20 seconds.

[0064] Control Example

[0065] Comparative Example 1

[0066] The difference between Control Example 1 and Example 1 is that after the aluminum foil is pretreated, chemical vapor deposition is not performed and the operation of step three is directly performed.

[0067] Comparative Example 2

[0068] The difference between Control Example 2 and Example 1 is that an equal amount of a polyurethane prepolymer without disulfide bonds (purchased from Hubei Chengfeng Chemical Co., Ltd., CAS: 103837-45-2, content 99%) is used to replace the polyurethane prepolymer containing disulfide bonds.

[0069] Comparative Example 3

[0070] The difference between this control example and Example 1 is that the pretreatment step of step 1 is eliminated.

[0071] Comparative Example 4

[0072] The difference between this comparative example and Example 1 is that the hot pressing process is eliminated.

[0073] Performance testing

[0074] Electrolyte penetration resistance test: According to GB / T 31408, an aluminum-plastic film sample (50 mm × 50 mm) was sealed in an electrolyte penetration test apparatus, filled with an EC / DMC mixture (1 M LiPF6), and placed in a 60°C constant temperature oven for 168 hours. The amount of water or electrolyte seepage from the outer surface of the sample was regularly weighed (accuracy 0.1 mg).

[0075] Interfacial adhesion test: According to ASTM D903, aluminum-plastic film samples were cut into strips with a width of 25 mm and a length of 150 mm. A 180° peel test was performed using a universal material testing machine (tensile rate 50 mm / min), and the peel strength (N / cm) was recorded. Test conditions: 23 ± 2°C, relative humidity 50 ± 5%.

[0076] Table 1 Experimental data of Examples 1 to 4 and Comparative Examples 1 to 4

[0077]

[0078] Combined with Preparation Example 1 and Figure 1 It can be seen that the functional group analysis is as follows: 3300 cm -1 (NH expansion), 1700 cm -1 (C=O stretching), 1530 cm -1 The negative peak (NH bending) confirms the presence of a carbamate bond (-NHCOO-); 2960 cm -1 (CH3 stretching), 2900 cm -1 (CH2 stretching), 1460 cm -1 (CH2 shear), 1375 cm -1 (CH3 bending), 1365 cm -1 The negative peak (CH2 swing) reflects the alkyl structure; 1250 cm -1 (CN telescopic), 1100 cm -1 (CC stretching) indicates that the molecular skeleton is intact; 675 cm -1 (CS stretching) is a characteristic of sulfide bonds. Disulfide bonds (-SS-) are at 525 cm -1 The negative peak at 2260 cm is shown, which proves its retention and supports the self-healing performance of the aluminum-plastic film. -1(-NCO) and 3400 cm -1 The (-OH) peak indicates that 2,2'-dithiodiethanol reacts completely with IPDI to generate the target polyurethane structure, which meets the requirements of interface enhancement and anti-microcrack.

[0079] Combining Examples 1 to 4 and Table 1, it can be seen that the seepage amount of Examples 1-4 is controlled at 0.3-0.4 mg / cm2, and the peel strength reaches 11.8-12.5 N / cm. The chemical bonding between GO and the carbon-based film and the synergistic effect of disulfide bond self-repair significantly improve the interfacial bonding strength, verifying the optimization effect of the process on microcrack suppression and durability.

[0080] Combining Example 1, Comparative Example 1 and Table 1, it can be seen that Example 1 is significantly better than Comparative Example 1 in terms of electrolyte penetration resistance and interface bonding strength. The seepage amount of Example 1 is 0.3 mg / cm 2 , much lower than 1.2 mg / cm in Comparative Example 1 2 The interfacial bonding peel strength was 12.5 N / cm, while that of Comparative Example 1 was only 8.0 N / cm. Example 1 formed a carbon-based film containing amino functional groups on the surface of aluminum foil via chemical vapor deposition, establishing an Al-N covalent bond and mechanical interlocking structure, thereby enhancing interfacial barrier properties and bonding strength.

[0081] Combining the analysis of Example 1, Comparative Example 2 and the data in Table 1, Example 1 is significantly better than Comparative Example 2 in terms of electrolyte penetration resistance and interface bonding strength. The seepage amount of Example 1 is 0.3 mg / cm 2 , lower than 0.8 mg / cm2 of Comparative Example 2 2 The peel strength was 12.5 N / cm, higher than the 9.5 N / cm in Comparative Example 2. Example 1 utilizes a polyurethane prepolymer containing disulfide bonds. Its disulfide bonds (-SS-) exhibit dynamic reversibility, enabling self-repair through breakage and recombination when microcracks are induced by electrolyte penetration, thereby inhibiting crack propagation and maintaining interfacial stability. Comparative Example 2, however, utilizes a polyurethane prepolymer without disulfide bonds. This lacks a self-repair mechanism, leading to accelerated microcrack propagation and a significant decrease in interfacial barrier properties and bonding strength. This demonstrates the critical role of disulfide bonds in the microcrack resistance of aluminum-plastic films.

[0082] Combining the analysis of Example 1, Comparative Example 3 and the data in Table 1, Example 1 is significantly better than Comparative Example 3 in terms of electrolyte penetration resistance and interface bonding strength. The seepage amount of Example 1 is 0.3 mg / cm 2 , much lower than 1.5 mg / cm in Comparative Example 3 2The peel strength was 12.5 N / cm, higher than the 7.5 N / cm of Comparative Example 3. Example 1 introduced hydroxyl groups and nano-rough structures on the aluminum foil surface through low-temperature plasma treatment, enhancing the Al-N covalent bonding and mechanical intercalation with the carbon-based film. However, in Comparative Example 3, which omitted pretreatment, the aluminum foil had low surface activity and poor adhesion to the carbon-based film, resulting in a significant decrease in interfacial bonding and increased electrolyte penetration, demonstrating the importance of pretreatment for the durability of aluminum-plastic films.

[0083] Combining the analysis of Example 1, Comparative Example 4 and the data in Table 1, Example 1 is superior to Comparative Example 4 in terms of electrolyte penetration resistance and interface bonding strength. The seepage amount of Example 1 is 0.3 mg / cm 2 , lower than 0.6 mg / cm in Comparative Example 4 2 The peel strength was 12.5 N / cm, higher than the 10.0 N / cm in Comparative Example 4. In Example 1, the hot pressing process promoted the fusion of the polyurethane layer and the polypropylene outer layer and induced the partial reduction of GO, enhancing the interfacial chemical bonding (CN, CO) and the dispersion of GO. In Comparative Example 4, the hot pressing process was omitted, resulting in insufficient GO modification, reduced interfacial bonding and barrier properties, and weakened microcrack suppression capabilities. This demonstrates the necessity of hot pressing for optimizing the performance of aluminum-plastic films.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing an aluminum-plastic film with enhanced interfacial bonding strength, characterized in that: The following technical steps are included: Step S1. Depositing a carbon-based film layer containing amino functional groups on the pretreated aluminum foil surface by chemical vapor deposition; Step S2. 1 wt% to 3 wt% of graphene oxide is incorporated into a polyurethane prepolymer containing disulfide bonds by a solution mixing method, 0.5-1 wt% of a photoinitiator is added, and the mixture is coated on the carbon-based film layer; Step S3. irradiating the coated composite structure with ultraviolet light; Step S4. Attaching a polymer outer layer to the cured polyurethane layer and completing the preparation of the aluminum-plastic film by a hot pressing process; In step S2, the preparation process of the polyurethane prepolymer containing disulfide bonds includes: mixing 2,2'-dithiodiethanol and isophorone diisocyanate in a molar ratio of 1:1.2, adding 0.1wt% of dibutyltin dilaurate catalyst, and reacting at 80°C for 4 hours under nitrogen protection to obtain a polyurethane prepolymer containing disulfide bonds with a molecular weight of 50,000-100,000.

2. The method for preparing an aluminum-plastic film having enhanced interfacial bonding strength according to claim 1, wherein: In step S1 , the deposition conditions are a temperature of 150-200° C. and a reaction time of 30-60 minutes.

3. The method for preparing an aluminum-plastic film with enhanced interfacial bonding strength according to claim 1, wherein: In step S2, the thickness of the carbon-based thin film layer is controlled to be 10-30 μm.

4. The method for preparing an aluminum-plastic film with enhanced interfacial bonding strength according to claim 1, wherein: The molecular weight of the 2,2'-dithiodiethanol is 2000-4000.

5. The method for preparing an aluminum-plastic film with enhanced interfacial bonding strength according to claim 1, wherein: The photoinitiator is benzophenone.

6. The method for preparing an aluminum-plastic film with enhanced interfacial bonding strength according to claim 1, wherein: In step S1 , the pretreatment step includes: performing low-temperature plasma treatment on the aluminum foil with a thickness of 20-50 μm, with a power of 100-200 W, an argon and oxygen mixed atmosphere, and a treatment time of 2-5 minutes.

7. The method for preparing an aluminum-plastic film with enhanced interfacial bonding strength according to claim 1, wherein: In step S4, the wavelength of ultraviolet light is 365nm and the intensity is 50-100mW / cm 2 , irradiation time 5-10 minutes.

8. The method for preparing an aluminum-plastic film with enhanced interfacial bonding strength according to claim 1, wherein: In step S4, the outer polymer layer is polypropylene with a thickness of 30-50 μm, and the temperature of the hot pressing process is 120-150° C., the pressure is 0.5-1.0 MPa, and the time is 10-20 seconds.

9. An aluminum-plastic film prepared based on the preparation method according to claim 1.

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