Aluminum-plastic film for enhancing interface bonding force and preparation method of aluminum-plastic film

Abstract

The invention discloses an aluminum-plastic film for enhancing interface bonding force and a preparation method of the aluminum-plastic film, and relates to the technical field of lithium batteries. The preparation method comprises the following steps: depositing a carbon-based thin film layer containing an amino functional group on the surface of a pretreated aluminum foil through a chemical vapor deposition method; the preparation method comprises the following steps: doping 1-3wt% of graphene oxide (GO) and 0.5-1wt% of a photoinitiator benzophenone into a disulfide bond-containing polyurethane prepolymer through a solution mixing method, and coating a carbon-based film with the mixture; ultraviolet light with the wavelength of 365 nm and the intensity of 50-100 mW / cm < 2 > is adopted to irradiate for 5-10 minutes for curing; finally, a polypropylene outer layer with the thickness of 30-50 microns is attached, and preparation is completed through a hot pressing technology. Through Al-N bond and GO modification and disulfide bond self-repairing mechanisms, the interface bonding force and electrolyte penetration resistance of the obtained aluminum-plastic film are remarkably enhanced, microcrack propagation is effectively inhibited, and the requirement for high durability of lithium battery packaging is met.

Description

Technical Field

[0001] The present invention relates to the field of lithium battery technology, and particularly to an aluminum-plastic film with enhanced interfacial bonding force and a preparation method thereof. Background Art

[0002] As a laminated material composed of aluminum foil and polymer film, the aluminum-plastic film has become a key material in the field of lithium-ion battery packaging due to its excellent moisture resistance, gas barrier property, and plasticity, and has been widely used in industries such as food packaging and pharmaceutical packaging. With the increasing demand of the lithium battery industry for high safety, long life, and high energy density, the technical research and development of aluminum-plastic films have gradually focused on the improvement of interfacial bonding force, corrosion resistance, and heat-sealing performance. At present, the preparation processes of aluminum-plastic films mainly include dry lamination and wet lamination, and the interfacial bonding is achieved 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 the interfacial performance, surface treatment methods such as chemical etching or plasma modification are often used in the prior art to increase the surface roughness and active sites of the aluminum foil, thereby improving the mechanical interlocking and chemical bonding effects. In addition, some studies have attempted to dope nanoparticles (such as silica or alumina) or functionalized polymers in the interfacial layer to improve the interfacial strength and durability. These technological advancements have promoted the optimization of the initial performance of aluminum-plastic films. However, their long-term stability in complex usage environments still needs to be further improved, especially their performance in the scenario of lithium battery electrolyte erosion has attracted much attention.

[0003] Although the prior art provides various paths for the interfacial enhancement of aluminum-plastic films, their deficiencies in specific microcrack application scenarios are still significant, especially in terms of the generation of interfacial microcracks and the long-term failure risk after electrolyte penetration. Taking lithium battery packaging as an example, when the aluminum-plastic film is in long-term contact with the electrolyte, electrolyte molecules penetrate through the interfacial defects and cause local stress concentration. Coupled with the difference in thermal expansion coefficients between the aluminum layer and the plastic layer and the chemical bond depolymerization of the adhesive layer, the initiation and propagation of microcracks are accelerated, which directly threatens the integrity of the packaging structure and the service life of the battery. Although the existing adhesives or surface modification technologies can improve the initial interfacial strength to a certain extent, their chemical erosion resistance is limited and it is difficult to effectively resist the interfacial degradation caused by the electrolyte. In addition, traditional mechanical interlocking or filler reinforcement methods mainly focus on the improvement of static performance, lacking a dynamic inhibition or damage evolution control mechanism for microcracks after 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 long-term contact with the electrolyte, electrolyte molecules penetrate through the interface defects and cause local stress concentration. The superposition of the thermal expansion coefficient difference between the aluminum layer and the plastic layer and the chemical bond depolymerization of the adhesive layer accelerates the initiation and expansion, which directly threatens the integrity of the packaging structure and the service life of the battery.

[0005] The present application provides a preparation method of an aluminum-plastic film with enhanced interfacial bonding force, including the following technical steps: Step S1. Deposit a carbon-based thin film layer containing amino functional groups on the surface of the pretreated aluminum foil by chemical vapor deposition; Step S2. Incorporate 1 wt% to 3 wt% of graphene oxide into the polyurethane prepolymer containing disulfide bonds by solution mixing method, add 0.5-1 wt% of photoinitiator, and coat the mixture on the carbon-based thin film layer; Step S3. Irradiate the coated composite structure with ultraviolet light; Step S4. Attach a polymer outer layer on the cured polyurethane layer and complete the preparation of the aluminum-plastic film by hot pressing process.

[0006] It should be noted that in Step S1, a carbon-based thin film containing amino functional groups is deposited on the surface of the pretreated aluminum foil by chemical vapor deposition (CVD). The amino group (-NH2) forms an Al-N covalent bond with the hydroxyl group on the aluminum surface, establishing a high-strength chemical bridge. At the same time, the nano-porous structure of the thin film further enhances the interfacial stability through mechanical interlocking, providing a solid substrate for subsequent interlayer bonding. In Step S2, 1-3 wt% of graphene oxide (GO) is incorporated into the polyurethane prepolymer containing disulfide bonds, and 0.5-1 wt% of photoinitiator is added, and it is coated on the surface of the carbon-based thin film by solution mixing method. The carboxyl, hydroxyl and epoxy groups of GO react with the amino groups of the carbon-based thin film to construct a chemically and physically synergistic interfacial transition layer, ensuring close contact between the coating and the thin film. At the same time, the photoinitiator reserves the reaction activity for subsequent curing. Step S3 initiates free radical polymerization by ultraviolet light irradiation, and the hydroxyl or ester group in the polyurethane cures with the amino group of the carbon-based thin film to form a dense network, significantly improving the interfacial bonding force and optimizing the interlayer stability. In Step S4, the polymer outer layer and the polyurethane layer are fused by hot pressing process. The amino groups on the surface of the carbon-based thin film are activated by high temperature and enhance their nucleophilicity, and react with the carboxyl, hydroxyl and epoxy groups on the surface of GO to strengthen the chemical bonding of the interfacial layer, and also cause partial reduction of GO. When the electrolyte penetration causes microcracks in the polyurethane layer, the modified GO in the interfacial layer can effectively capture trace moisture or polar solvent molecules due to the retention of some hydrophilic functional groups, constructing a local high-humidity microenvironment. This microenvironment reduces the activation energy of the dynamic exchange of disulfide bonds in the polyurethane layer, accelerates the fracture and recombination under stress or humidity stimulation, and promotes the self-repair of microcracks.

[0007] As a preferred technical solution for the preparation method of an aluminum-plastic film to enhance the interfacial bonding force, 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 these deposition conditions, a uniform carbon-based film is formed to enhance the interfacial bonding force.

[0009] As a preferred technical solution for the preparation method of an aluminum-plastic film to enhance the interfacial bonding force, in step S2, the thickness of the carbon-based film layer is controlled within 10 - 30 μm.

[0010] It should be noted that a moderate thickness not only improves the interfacial bonding force, resists the penetration of the electrolyte, promotes the self-healing efficiency, effectively inhibits the propagation of microcracks, and enhances the long-term durability and anti-failure performance of the aluminum-plastic film in an electrolyte erosion environment.

[0011] As a preferred technical solution for the preparation method of an aluminum-plastic film to enhance the interfacial bonding force, 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 0.1 wt% 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, contains a disulfide bond (-S-S-) in its molecular chain, which has dynamic reversibility, while the terminal hydroxyl group (-OH) has high reactivity; IPDI, as a hard segment monomer, has two isocyanate groups (-NCO) that can undergo an addition reaction with the hydroxyl group to form a urethane bond (-NHCOO-). Through the ratio of 1:1.2, the slight excess of IPDI ensures the sufficiency of isocyanate groups in the reaction system, promotes chain growth rather than excessive cross-linking, and at the same time avoids the formation of urea bonds or isocyanurates generated by side reactions. Adding 0.1 wt% of dibutyltin dilaurate catalyst significantly reduces the activation energy of the reaction between the hydroxyl group and isocyanate, and accelerates the formation of urethane bonds through coordination catalysis, enabling the reaction to proceed efficiently at a mild temperature of 80 °C. The nitrogen protection environment effectively excludes the interference of moisture and oxygen, prevents the reaction of isocyanate with water to generate amine by-products, and ensures the purity of the polymer structure and the integrity of the disulfide bond. After 4 hours of reaction, 2,2'-dithiodiethanol and IPDI form a linear or slightly branched polyurethane prepolymer with a molecular weight of 50,000 - 100,000 through stepwise polymerization, and the disulfide bonds are evenly distributed in the soft segment, laying the foundation for subsequent self-healing performance. In the application of the aluminum-plastic film, the dynamic reversibility of the disulfide bond can break and recombine under stress or humidity stimulation when microcracks are caused by electrolyte penetration, repairing microscopic damage, thereby enhancing the interfacial durability and anti-microcrack ability.

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

[0014] It should be noted that this molecular weight range ensures good fluidity and dispersibility of 2,2'-dithiobisethanol in the reaction system, reduces the system viscosity, is conducive to the uniform reaction of IPDI at a molar ratio of 1:1.2, and avoids excessive crosslinking 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 the preparation method of an aluminum-plastic film for enhancing interfacial bonding strength, the photosensitizer is benzophenone.

[0016] It should be noted that the photosensitizer benzophenone initiates free radical polymerization through photoexcitation in the ultraviolet curing of aluminum-plastic film preparation, enhancing the interfacial bonding strength.

[0017] As a preferred technical solution for the preparation method of an aluminum-plastic film for enhancing interfacial bonding strength, in step S1, the pretreatment steps include: subjecting an aluminum foil with a thickness of 20 - 50 μm to low-temperature plasma treatment at a power of 100 - 200 W in an argon-oxygen mixed atmosphere for 2 - 5 minutes.

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

[0019] As a preferred technical solution for the preparation method of an aluminum-plastic film for enhancing 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 appropriate light intensity and time ensure uniform curing, retain the activity of disulfide bonds, promote self-healing efficiency, while extending the electrolyte penetration path, reducing the risk of microcracks, and enhancing the durability and anti-failure performance of the encapsulation structure.

[0021] As a preferred technical solution for the preparation method of an aluminum-plastic film for enhancing interfacial bonding strength, in step S4, the polymer outer layer is polypropylene with a thickness of 30 - 50 μm, 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.

[0022] It should be noted that through the above process, tight fusion with the polyurethane layer can be achieved, enhancing the mechanical toughness and barrier properties of the aluminum-plastic film.

[0023] Through the synergistic effect of the carbon-based thin film containing amino functional groups, GO modification, and disulfide bond self-healing, the aluminum-plastic film of the present invention significantly improves the interfacial bonding force and the anti-electrolyte penetration performance. Experimental data shows that the peel strength reaches 11.8 - 12.5 N / cm, far exceeding the target value of 10 N / cm, and the exudation amount is only 0.3 - 0.4 mg / cm 2 , lower than the target value of 0.5 mg / cm 2 , demonstrating excellent interfacial stability and barrier properties. The Al-N covalent bond and nano-pores of the carbon-based thin film enhance the interlayer bonding. The doping of GO and the modification induced by hot pressing optimize the interfacial chemical bonding. The dynamic reversibility of the disulfide bond enables efficient self-healing when micro-cracks are caused by electrolyte erosion, extends the penetration path, effectively inhibits crack propagation, and significantly improves the durability and anti-failure performance of the aluminum-plastic film in lithium battery packaging, meeting the requirements of high safety and long life. Description of the Drawings

[0024] Figure 1 It is the infrared spectrum of the polyurethane prepolymer containing disulfide bonds prepared in Preparation Example 1. Detailed Embodiments

[0025] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following describes the detailed embodiments of the present invention in conjunction with the embodiments of the specification.

[0026] In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0027] Secondly, the so-called "one embodiment" or "embodiment" herein refers to specific features, structures, or characteristics that can be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selectively exclusive embodiment from other embodiments.

[0028] Preparation Examples Preparation Example 1 The preparation process of the polyurethane prepolymer containing disulfide bonds includes: taking 2,2'-dithiobisethanol (molecular weight of 4000) and isophorone diisocyanate and mixing them in a molar ratio of 1:1.2, adding 0.1 wt% 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.

[0029] Preparation Example 2 The preparation process of the polyurethane prepolymer containing disulfide bonds includes: taking 2,2'-dithiobisethanol (with a molecular weight of 2000) and isophorone diisocyanate and mixing them at a molar ratio of 1:1.2, adding 0.1 wt% 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.

[0030] Preparation Example 3 The preparation process of the polyurethane prepolymer containing disulfide bonds includes: taking 2,2'-dithiobisethanol (with a molecular weight of 3000) and isophorone diisocyanate and mixing them at a molar ratio of 1:1.2, adding 0.1 wt% 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] Example Example 1 Example 1 A method for preparing an aluminum-plastic film with enhanced interfacial bonding strength includes the following technical steps: Step 1. Perform low-temperature plasma treatment on an aluminum foil with a thickness of 20 μm, with a power of 100 W, in an argon-oxygen mixed atmosphere, and the treatment time is 5 minutes; Step 2. Deposit a carbon-based thin film layer containing amino functional groups on the surface of the pretreated aluminum foil, with the thickness of the carbon-based thin film layer controlled at 10 μm, and the deposition conditions are a temperature of 150 °C and a reaction time of 60 minutes; Step 3. Incorporate 3 wt% of graphene oxide into the polyurethane prepolymer containing disulfide bonds (Preparation Example 1) by solution mixing method, add 0.5 wt% of benzophenone, and coat this mixture on the carbon-based thin film layer; Step 4. Perform ultraviolet light irradiation on the coated composite structure, with the wavelength of the ultraviolet light being 365 nm and the intensity being 100 mW / cm 2 , and the irradiation time is 5 minutes; Step 5. Attach a polymer outer layer on 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, and the temperature of the hot pressing process is 150 °C, the pressure is 0.5 MPa, and the time is 20 seconds.

[0032] Example 2 Example 2 A method for preparing an aluminum-plastic film with enhanced interfacial bonding strength includes the following technical steps: Step 1. Perform low-temperature plasma treatment on an aluminum foil with a thickness of 50 μm, with a power of 200 W, in an argon-oxygen mixed atmosphere, and the treatment time is 2 minutes; Step 2. Deposit a carbon-based thin film layer containing amino functional groups on the surface of the pretreated aluminum foil by chemical vapor deposition. The thickness of the carbon-based thin film layer is controlled at 30 μm, and the deposition conditions are a temperature of 200 °C and a reaction time of 30 minutes; Step 3. Incorporate 1 wt% of graphene oxide and add 1 wt% of benzophenone into the polyurethane prepolymer containing disulfide bonds (Preparation Example 2) by solution mixing method, and coat this mixture on the carbon-based thin film layer; Step 4. Irradiate the coated composite structure with ultraviolet light. The wavelength of the ultraviolet light is 365 nm and the intensity is 50 mW / cm 2 , and the irradiation time is 10 minutes; Step 5. Attach a polymer outer layer on the cured polyurethane layer, and complete the preparation of the aluminum-plastic film by hot pressing. The polymer outer layer is polypropylene with a thickness of 50 μm. The temperature of the hot pressing process is 120 °C, the pressure is 1.0 MPa, and the time is 10 seconds.

[0033] Example 3 The preparation method of an aluminum-plastic film for enhancing the interfacial bonding force in Example 3 includes the following technical steps: Step 1. Perform low-temperature plasma treatment on an aluminum foil with a thickness of 30 μm, with a power of 150 W, in an argon-oxygen mixed atmosphere, and the treatment time is 3 minutes; Step 2. Deposit a carbon-based thin film layer containing amino functional groups on the surface of the pretreated aluminum foil by chemical vapor deposition. The thickness of the carbon-based thin film layer is controlled at 20 μm, and the deposition conditions are a temperature of 200 °C and a reaction time of 50 minutes; Step 3. Incorporate 2 wt% of graphene oxide and add 0.8 wt% of benzophenone into the polyurethane prepolymer containing disulfide bonds (Preparation Example 3) by solution mixing method, and coat this mixture on the carbon-based thin film layer; Step 4. Irradiate the coated composite structure with ultraviolet light. The wavelength of the ultraviolet light is 365 nm and the intensity is 80 mW / cm 2 , and the irradiation time is 10 minutes; Step 5. Attach a polymer outer layer on the cured polyurethane layer, and complete the preparation of the aluminum-plastic film by hot pressing. The polymer outer layer is polypropylene with a thickness of 40 μm. The temperature of the hot pressing process is 120 °C, the pressure is 0.8 MPa, and the time is 10 seconds.

[0034] Example 4 The preparation method of an aluminum-plastic film for enhancing the interfacial bonding force in Example 4 includes the following technical steps: Step 1. Perform low-temperature plasma treatment on an aluminum foil with a thickness of 50 μm, with a power of 200 W, in an argon-oxygen mixed atmosphere, and the treatment time is 3 minutes; Step 2. Deposit a carbon-based thin film layer containing amino functional groups on the surface of the pretreated aluminum foil by chemical vapor deposition. The thickness of the carbon-based thin film layer is controlled at 10 μm, and the deposition conditions are a temperature of 150 °C and a reaction time of 50 minutes; Step 3. Incorporate 2 wt% of graphene oxide into the polyurethane prepolymer containing disulfide bonds (Preparation Example 2) by solution mixing method, add 0.8 wt% of benzophenone, and coat the mixture on the carbon-based thin film layer; Step 4. Irradiate the coated composite structure with ultraviolet light. The wavelength of the ultraviolet light is 365 nm, and the intensity is 80 mW / cm 2 , and the irradiation time is 10 minutes; Step 5. Attach a polymer outer layer on the cured polyurethane layer, and complete the preparation of the aluminum-plastic film by hot pressing process. The polymer outer layer is polypropylene with a thickness of 30 μm. The temperature of the hot pressing process is 120 °C, the pressure is 0.8 MPa, and the time is 20 seconds.

[0035] Control Example Control Example 1 The difference between this Control Example 1 and Example 1 is that after the pretreatment of the aluminum foil, the operation of Step 3 is directly carried out without chemical vapor deposition.

[0036] Control Example 2 The difference between this Control Example 2 and Example 1 is that the 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 in equal amount.

[0037] Control Example 3 The difference between this control example and Example 1 is that the pretreatment step in Step 1 is cancelled.

[0038] Control Example 4 The difference between this control example and Example 1 is that the hot pressing process is cancelled.

[0039] Performance Detection Test Anti-electrolyte penetration performance test: According to the GB / T 31408 standard, seal the aluminum-plastic film sample (50 mm × 50 mm) in an electrolyte penetration test device, fill it with an EC / DMC mixture (1 M LiPF6), and place it in a constant temperature oven at 60 °C for 168 hours. Regularly weigh the amount of moisture or electrolyte seeping out on the outside of the sample (accuracy 0.1 mg); Interface bonding strength test: According to the ASTM D903 standard, cut the aluminum-plastic film sample into strips with a width of 25 mm and a length of 150 mm, and use a universal material testing machine (tensile rate 50 mm / min) to conduct a 180° peel test, and record the peel strength (N / cm). The test conditions are: 23 ± 2 °C, relative humidity 50 ± 5%.

[0040] Table 1 Experimental data of Examples 1 to 4 and Comparative Examples 1 to 4 Combined with Preparation Example 1 and Figure 1 It can be seen that the functional groups are analyzed as follows: 3300 cm -1 (N-H stretching), 1700 cm -1 (C=O stretching), 1530 cm -1 (N-H bending) negative peak confirms the presence of urethane bond (-NHCOO-); 2960 cm -1 (CH3 stretching), 2900 cm -1 (CH2 stretching), 1460 cm -1 (CH2 shearing), 1375 cm -1 (CH3 bending), 1365 cm -1 (CH2 rocking) negative peak reflects the alkyl structure; 1250 cm -1 (C-N stretching), 1100 cm -1 (C-C stretching) indicates the integrity of the molecular skeleton; 675 cm -1 (C-S stretching) is the characteristic of the thioether bond. The disulfide bond (-S-S-) shows a negative peak at 525 cm -1 which proves its retention and supports the self-healing performance of the aluminum-plastic film. There is no peak at 2260 cm -1 (-NCO) and 3400 cm -1 (-OH) in the spectrum, indicating that 2,2'-dithiobisethanol reacts completely with IPDI to form the target polyurethane structure, meeting the requirements of interface enhancement and anti-microcrack.

[0041] Combined with Examples 1 to 4 and Table 1, it can be seen that the exudation 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. Due to the significant synergistic effect of chemical bonding between GO and the carbon-based film and disulfide bond self-healing, the interface bonding force is significantly improved, verifying the optimization effect of the process on microcrack inhibition and durability.

[0042] Combined with Example 1, Comparative Example 1 and Table 1, it can be seen that Example 1 is significantly superior to Comparative Example 1 in terms of anti-electrolyte penetration performance and interface bonding force. The exudation amount of Example 1 is 0.3 mg / cm 2 , much lower than 1.2 mg / cm of Comparative Example 1 2; The interfacial adhesion peel strength is 12.5 N / cm, while that of Comparative Example 1 is only 8.0 N / cm. In Example 1, a carbon-based film containing amino functional groups was formed on the surface of the aluminum foil by chemical vapor deposition, constructing an Al-N covalent bond and a mechanical interlocking structure, enhancing the interfacial barrier property and adhesion.

[0043] Combined with the data analysis of Example 1, Comparative Example 2 and Table 1, Example 1 is significantly superior to Comparative Example 2 in terms of anti-electrolyte penetration performance and interfacial adhesion. The exudation amount of Example 1 is 0.3 mg / cm 2 , lower than 0.8 mg / cm of Comparative Example 2 2 ; The peel strength is 12.5 N / cm, higher than 9.5 N / cm of Comparative Example 2. In Example 1, a polyurethane prepolymer containing disulfide bonds was used. Its disulfide bonds (-S-S-) have dynamic reversibility and can achieve self-healing through fracture and recombination when microcracks are initiated by electrolyte penetration, thereby inhibiting crack propagation and maintaining interfacial stability. While Comparative Example 2 uses a polyurethane without disulfide bonds, lacking a self-healing mechanism, resulting in accelerated microcrack propagation, significant decline in interfacial barrier property and adhesion, verifying the key role of disulfide bonds in the anti-microcrack performance of aluminum-plastic films.

[0044] Combined with the data analysis of Example 1, Comparative Example 3 and Table 1, Example 1 is significantly superior to Comparative Example 3 in terms of anti-electrolyte penetration performance and interfacial adhesion. The exudation amount of Example 1 is 0.3 mg / cm 2 , much lower than 1.5 mg / cm of Comparative Example 3 2 ; The peel strength is 12.5 N / cm, higher than 7.5 N / cm of Comparative Example 3. In Example 1, hydroxyl groups and nano-rough structures were introduced on the surface of the aluminum foil by low-temperature plasma treatment, enhancing the Al-N covalent bond binding and mechanical interlocking with the carbon-based film. While Comparative Example 3 omitted the pretreatment, the surface activity of the aluminum foil was low and the adhesion of the carbon-based film was poor, resulting in a significant decline in interfacial adhesion and increased electrolyte penetration, verifying the importance of pretreatment for the durability of aluminum-plastic films.

[0045] Combined with the data analysis of Example 1, Comparative Example 4 and Table 1, Example 1 is superior to Comparative Example 4 in terms of anti-electrolyte penetration performance and interfacial adhesion. The exudation amount of Example 1 is 0.3 mg / cm 2 , lower than 0.6 mg / cm of Comparative Example 4 2 ; The peel strength is 12.5 N / cm, higher than 10.0 N / cm of Comparative Example 4. In Example 1, the hot pressing process promoted the fusion of the polyurethane layer and the polypropylene outer layer, and induced partial reduction of GO, enhancing the interfacial chemical bonding (C-N, C-O) and the dispersion of GO. While Comparative Example 4 cancelled the hot pressing, the modification of GO was insufficient, resulting in a decline in interfacial adhesion and barrier property and weakened microcrack inhibition ability, verifying the necessity of the hot pressing process for optimizing the performance of aluminum-plastic films.

[0046] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing an aluminum-plastic film with enhanced interfacial bonding strength, characterized in that: The technical steps include: Step S1. depositing a carbon-based film layer containing amino functional groups on the surface of the pretreated aluminum foil by chemical vapor deposition; Step S2. adding 1 wt % to 3 wt % of graphene oxide to a polyurethane prepolymer containing disulfide bonds by a solution mixing method, adding 0.5-1 wt % of a photoinitiator, and coating the mixture on a carbon-based film layer; Step S3. irradiating the coated composite structure with ultraviolet light; Step S4. attaching a polymer outer layer to the upper layer of 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, reacting at 80°C for 4 hours under nitrogen protection, and obtaining a polyurethane prepolymer containing disulfide bonds with a molecular weight of 50,000-100,000.

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

6. The method for preparing an aluminum-plastic film with enhanced interfacial bonding strength according to claim 1, characterized in that: 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, characterized in that: In step S4, the wavelength of the 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, characterized in that: In step S4, the polymer outer layer is polypropylene with a thickness of 30-50 μm, 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 by the preparation method according to claim 1.

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