PP adhesive tape suitable for polymer soft package battery and preparation method of PP adhesive tape

Abstract

The invention discloses a PP adhesive tape suitable for a polymer soft package battery and a preparation method of the PP adhesive tape, and relates to the field of lithium ion battery packaging materials. The PP adhesive tape comprises a polypropylene carrier film and a composite adhesive layer, wherein the composite adhesive layer comprises the polypropylene carrier film, an epoxy-phenolic aldehyde-silane hybrid adhesive layer, a nano-montmorillonite barrier filler, a phosphorus-nitrogen intumescent flame retardant, a polybenzoxazole short fiber, a quaternary phosphonium salt corrosion inhibitor, a silane coupling agent and an antioxidant. According to the composite adhesive layer disclosed by the invention, a self-repairing passivation film is constructed through nano-montmorillonite synergistic barrier, phosphorus-nitrogen intumescent flame retardant and polybenzoxazole short fiber synergistic flame retardance, and quaternary phosphonium salt corrosion inhibitor and silane coupling agent, so that multiple functions of high temperature resistance, electrolyte resistance, flame retardance and corrosion inhibition are realized. The PP adhesive tape disclosed by the invention is excellent in comprehensive performance and suitable for fixing and packaging a roll core of a polymer soft package battery.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery packaging materials, and in particular to a PP tape suitable for polymer soft-pack batteries and its preparation method. Background Technology

[0002] Polymer pouch batteries have been widely used in consumer electronics, electric vehicles, and energy storage due to their advantages such as high energy density, thinness, and design flexibility. During the production of pouch batteries, adhesive tape is used to fix and seal the core to prevent it from loosening and to ensure the overall structural stability of the battery. Traditional battery encapsulation tapes typically use polyethylene terephthalate (PET) as the base material, combined with acrylate or rubber-based pressure-sensitive adhesives.

[0003] However, recent studies have found that PET exhibits serious chemical stability issues in lithium-ion battery electrolyte environments. Battery electrolytes typically consist of organic carbonate solvents (such as dimethyl carbonate (DMC) and ethylene carbonate (EC)) and lithium salts (such as lithium hexafluorophosphate). The composition of PET is shown in studies. Studies have shown that PET undergoes a methanololysis reaction in electrolytes containing DMC, producing dimethyl terephthalate (DMT). DMT molecules act as redox shuttles within the battery, being reduced at the positive electrode and oxidized at the negative electrode, forming a continuous discharge circuit. This leads to significant self-discharge, severely impacting the battery's charge retention capacity and calendar life.

[0004] A 2023 study published in *Nature Materials* systematically revealed that PET tape is a key cause of reversible self-discharge in lithium-ion batteries and demonstrated that replacing PET with chemically more stable materials (such as polypropylene (PP) or polyimide (PI)) can significantly reduce or even completely eliminate reversible self-discharge. This discovery overturned the industry's general understanding of PET as an internal battery material, indicating that it is not stable and unchanging within the battery chemistry system.

[0005] In addition, traditional PET tapes also have the following problems: insufficient high temperature resistance, which makes them prone to softening and deformation during battery hot pressing or high temperature storage; poor flame retardancy, which makes it difficult to meet the stringent safety requirements of power batteries; insufficient bonding strength to the inner layer of aluminum-plastic film (usually CPP), which makes them prone to delamination after long-term use; and the adhesive layer is prone to swelling after long-term immersion in electrolyte, which leads to a decrease in bonding performance.

[0006] Therefore, developing a novel battery encapsulation tape that is chemically stable, high-temperature resistant, flame-retardant, and has excellent adhesion to aluminum-plastic films has become a pressing technical problem to be solved in this field. Summary of the Invention

[0007] This invention aims to overcome the aforementioned defects of existing PET tape technology and provide a PP tape suitable for polymer soft-pack batteries and its preparation method. This fundamentally avoids the self-discharge problem caused by DMT generated from PET degradation in the electrolyte; improves the tape's high-temperature resistance, enabling it to maintain good dimensional stability above 200°C; enhances the tape's flame-retardant properties, ensuring battery safety; improves the tape's adhesion strength to the aluminum-plastic film inner layer (CPP), ensuring long-term reliability; and provides corrosion-inhibiting properties to protect the aluminum electrode from electrolyte corrosion.

[0008] To achieve the above-mentioned technical objectives, the first aspect of the present invention provides a PP tape suitable for polymer soft-pack batteries, comprising a polypropylene carrier film and a composite adhesive layer. The composite adhesive layer, by weight percentage, comprises the following components: 40-55% polypropylene carrier film, 20-30% epoxy-phenolic-silane hybrid adhesive layer, and nano-... - Montmorillonite barrier filler 5~12%, phosphorus and nitrogen intumescent flame retardant 3~8%, polybenzoxazole short fiber 2~6%, quaternary phosphonium salt corrosion inhibitor 1~4%, silane coupling agent 1~4%, antioxidant 0.5~2%; The epoxy-phenolic-silane hybrid adhesive layer is prepared by crosslinking epoxy resin, phenolic resin and silane coupling agent; The nano - Montmorillonite barrier filler is prepared by surface modification of nano-silica and montmorillonite; The thickness of the polypropylene carrier film is 25~50μm, and the thickness of the composite adhesive layer is 15~30μm.

[0009] Polypropylene (PP) as the base material fundamentally solves the self-discharge problem of PET tape. PP molecular chains are composed of saturated carbon-carbon bonds and do not contain easily hydrolyzed functional groups such as ester groups. It exhibits extremely high chemical stability in lithium-ion battery electrolytes and will not undergo degradation reactions like PET to form DMT. Preferably, in the epoxy-phenolic-silane hybrid adhesive layer, the mass ratio of epoxy resin, phenolic resin and silane coupling agent is (3~5):(2~4):(1~2).

[0010] Preferably, the nano In the montmorillonite barrier filler, the average particle size of nano-silica is 20~100nm, and the montmorillonite is organically modified montmorillonite with a lamellar spacing of 1.5~3.0nm.

[0011] Preferably, the phosphorus-nitrogen intumescent flame retardant is composed of ammonium polyphosphate, pentaerythritol and melamine in a mass ratio of (2~4):(1~2):(1~2).

[0012] Preferably, the polybenzoxazole short fiber has a diameter of 10~20μm, a length of 50~200μm, and a tensile strength greater than 5.8GPa.

[0013] Preferably, the quaternary phosphonium salt corrosion inhibitor is at least one of tetrabutylphosphonium bromide, tetraphenylphosphonium bromide, or triphenylbenzylphosphonium chloride.

[0014] Preferably, the silane coupling agent is at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, or γ-methacryloyloxypropyltrimethoxysilane.

[0015] Preferably, the antioxidant is at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris[2,4-di-tert-butylphenyl]phosphite, or octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0016] Preferably, the quaternary phosphonium salt corrosion inhibitor is encapsulated using microencapsulation technology, with microcapsule particle size of 10~50μm and wall material of polyaniline or urea-formaldehyde resin.

[0017] On the other hand, the present invention proposes a method for preparing PP tape suitable for polymer soft-pack batteries, comprising the following steps: S1: Weigh each component raw material according to the formula ratio, and combine the epoxy-phenolic-silane hybrid adhesive layer and nano- - Montmorillonite barrier filler, phosphorus and nitrogen intumescent flame retardant, polybenzoxazole short fiber, quaternary phosphonium salt corrosion inhibitor, silane coupling agent and antioxidant are added to a high-speed disperser and dispersed at 1500-2500 rpm for 30-60 minutes at 60-80℃ to obtain composite adhesive slurry. The high-speed disperser has a rotation speed of 2000 rpm, a dispersion time of 45 minutes, and a dispersion temperature of 70℃. S2: The composite adhesive slurry obtained in step S1 is uniformly coated onto the surface of the polypropylene carrier film using a precision coating method. The coating speed is 5~15m / min and the coating thickness is 15~30μm. S3: The polypropylene carrier film coated with the composite adhesive layer obtained in step S2 is sent into a hot air circulating oven for heat curing treatment. The curing temperature is 120~180℃ and the curing time is 5~15 minutes. The thermosetting process employs a segmented curing method: first, pre-curing at 120~140℃ for 3~5 minutes, followed by main curing at 160~180℃ for 5~10 minutes. S4: The PP tape cured in step S3 is cooled to room temperature by a cooling roller, wound up under constant tension, and then cut and packaged to obtain the PP tape.

[0018] The beneficial effects of this application are: 1. In the design of the epoxy-phenolic-silane hybrid adhesive layer of the present invention, the phenolic resin undergoes a cross-linking reaction at high temperature to form a dense and stable three-dimensional network structure, which endows the adhesive layer with excellent high-temperature stability and dimensional stability; the epoxy resin provides excellent adhesion and chemical corrosion resistance; the silane coupling agent forms a strong -Si-O- covalent bond between the substrate and the adhesive layer, which significantly improves the interfacial adhesion.

[0019] 2. This invention utilizes nanotechnology. The particles fill the tiny pores in the polymer matrix, and the montmorillonite sheets form tortuous paths in the adhesive layer. The two work together to construct a complex three-dimensional nanonetwork, which effectively hinders the migration of electrolyte and its dissolved substances, and significantly improves the barrier performance of the tape.

[0020] 3. This invention utilizes a synergistic effect between a phosphorus-nitrogen intumescent flame retardant and polybenzoxazole short fibers. When heated, the phosphorus-nitrogen intumescent flame retardant decomposes to produce non-combustible gases, causing the adhesive layer to expand and foam, forming a porous charred layer. The polybenzoxazole short fibers, as an inherently flame-retardant material, act as a skeletal reinforcement within the charred layer, making the char layer denser and more stable. This synergistic flame-retardant mechanism allows the tape to easily pass the UL-94VTM-0 flame retardancy test.

[0021] 4. Regarding corrosion inhibition, this invention employs the synergistic effect of quaternary phosphonium salt corrosion inhibitor and silane coupling agent. The quaternary phosphonium salt forms a dense hydrophobic protective film on the surface of the aluminum electrode, while the silane coupling agent forms stable -Si-O-Al- covalent bonds with the aluminum surface. Together, they construct a self-healing passivation film, providing long-term protection of the aluminum electrode from electrolyte corrosion.

[0022] In a preferred embodiment, the PP tape of the present invention suitable for polymer soft-pack batteries exhibits excellent chemical stability, does not generate DMT after long-term immersion in electrolyte, and reduces self-discharge rate by more than 70%; it has good high-temperature resistance, with a heat shrinkage rate of less than 0.3% after 30 minutes at 150°C; it has excellent flame retardant properties, passing the UL-94VTM-0 rating test; its adhesion strength to the aluminum-plastic film CPP layer is greater than 5N / 25mm, and its peel strength retention rate is greater than 90%; it has good corrosion inhibition properties, effectively protecting the aluminum electrode post. Attached Figure Description

[0023] Figure 1 This is a physical image of the PP tape suitable for polymer soft-pack batteries prepared according to Example 1 of this application. Detailed Implementation

[0024] Example 1 A PP tape suitable for polymer soft-pack batteries includes a polypropylene carrier film and a composite adhesive layer.

[0025] The composite adhesive layer, by weight percentage, comprises the following components: 46% polypropylene carrier film, 25% epoxy-phenolic-silane hybrid adhesive layer, and nano-... - 8% montmorillonite barrier filler, 5% phosphorus-nitrogen intumescent flame retardant, 4% polybenzoxazole short fiber, 2% quaternary phosphonium salt corrosion inhibitor, 2% silane coupling agent, and 1% antioxidant.

[0026] The polypropylene carrier membrane is made of polypropylene resin of grade T30S (melt index 3.0 g / 10 min, isotacticity 96%) produced by Sinopec Group, and is biaxially stretched to obtain a thickness of 38 μm.

[0027] The epoxy-phenolic-silane hybrid adhesive layer is prepared by crosslinking epoxy resin, phenolic resin, and silane coupling agent. The epoxy resin used is NPES-901 epoxy resin produced by Nan Ya Epoxy Resin (Kunshan) Co., Ltd., the phenolic resin is PF-8012 phenolic resin produced by Shandong Shengquan New Material Co., Ltd., and the silane coupling agent is Z-6040 silane coupling agent (γ-glycidoxypropyltrimethoxysilane) produced by Dow Corning (China) Investment Co., Ltd. The mass ratio of epoxy resin, phenolic resin, and silane coupling agent is 4:3:1.5.

[0028] The nano - Montmorillonite barrier filler is prepared by surface modification of nano-silica and montmorillonite. The nano-silica is AEROSIL200 fumed silica (average particle size 12nm, specific surface area 200m² / g) produced by Evonik Specialty Chemicals (Shanghai) Co., Ltd., and the montmorillonite is DK1 organic-modified montmorillonite (lamellar spacing 2.1nm) produced by Zhejiang Fenghong New Material Co., Ltd. The mass ratio of nano-silica to montmorillonite is 3:2.

[0029] The phosphorus-nitrogen intumescent flame retardant is composed of ammonium polyphosphate, pentaerythritol, and melamine in a mass ratio of 3:1.5:1.5. The ammonium polyphosphate is APP-201 flame retardant (degree of polymerization greater than 1000) produced by Zhejiang Wansheng Co., Ltd., the pentaerythritol is industrial-grade pentaerythritol produced by Hubei Yihua Chemical Co., Ltd., and the melamine is industrial-grade melamine produced by Sichuan Jinxiang Chemical Industry Group Co., Ltd.

[0030] The polybenzoxazole short fiber is made of Zylon chopped fiber (13 μm in diameter, 100 μm in length, and tensile strength 5.8 GPa) manufactured by Toray Industries, Ltd. of Japan.

[0031] The quaternary phosphonium salt corrosion inhibitor used is tetrabutylphosphonium bromide (99% purity) produced by Shanghai Maclean Biochemical Technology Co., Ltd.

[0032] The antioxidant used is Irganox 1010 antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) produced by BASF (China) Co., Ltd.

[0033] The thickness of the polypropylene carrier film is 38 μm, and the thickness of the composite adhesive layer is 22 μm.

[0034] The preparation method includes: S1: Weighing each component raw material according to the formula ratio, and then preparing the epoxy-phenolic-silane hybrid adhesive layer and nano-polymers. - Montmorillonite barrier filler, phosphorus-nitrogen intumescent flame retardant, polybenzoxazole short fiber, quaternary phosphonium salt corrosion inhibitor, silane coupling agent and antioxidant are added to a high-speed disperser and dispersed at 2000 rpm for 45 minutes at 70°C to obtain a composite adhesive slurry; S2: The composite adhesive slurry obtained in step S1 is uniformly coated onto the surface of a polypropylene carrier film using a precision coating method at a coating speed of 10 m / min and a coating thickness of 22 μm; S3: The polypropylene carrier film coated with the composite adhesive layer obtained in step S2 is sent to a hot air circulating oven for segmented heat curing treatment. First, it is pre-cured at 130°C for 4 minutes, and then mainly cured at 170°C for 8 minutes; S4: The PP tape cured in step S3 is cooled to room temperature by a cooling roller, wound up under constant tension, and then cut and packaged to obtain the final product.

[0035] Example 2 A PP tape suitable for polymer soft-pack batteries includes a polypropylene carrier film and a composite adhesive layer.

[0036] The composite adhesive layer, by weight percentage, comprises the following components: 55% polypropylene carrier film, 20% epoxy-phenolic-silane hybrid adhesive layer, and nano-... - Montmorillonite barrier filler 12%, phosphorus and nitrogen intumescent flame retardant 3%, polybenzoxazole short fiber 2%, quaternary phosphonium salt corrosion inhibitor 4%, silane coupling agent 4%, antioxidant 2%.

[0037] The epoxy-phenolic-silane hybrid adhesive layer is prepared by crosslinking epoxy resin, phenolic resin and silane coupling agent, wherein the mass ratio of epoxy resin, phenolic resin and silane coupling agent is 3:2:1.

[0038] The nano - Montmorillonite barrier filler is prepared by surface modification of nano-silica and montmorillonite. The average particle size of the nano-silica is 20 nm, and the montmorillonite is organically modified with a lamellar spacing of 1.5 nm. The mass ratio of nano-silica to montmorillonite is 2:3.

[0039] The phosphorus-nitrogen intumescent flame retardant is composed of ammonium polyphosphate, pentaerythritol, and melamine in a mass ratio of 2:1:1.

[0040] The polybenzoxazole short fiber has a diameter of 10 μm, a length of 50 μm, and a tensile strength greater than 5.8 GPa.

[0041] The quaternary phosphonium salt corrosion inhibitor is tetraphenylphosphonium bromide.

[0042] The silane coupling agent is γ-aminopropyltriethoxysilane.

[0043] The thickness of the polypropylene carrier film is 25 μm, and the thickness of the composite adhesive layer is 15 μm.

[0044] The preparation method is the same as in Example 1, except that: in step S1, the speed of the high-speed disperser is 1500 rpm, the dispersion time is 60 minutes, and the dispersion temperature is 60℃; in step S2, the coating speed is 5 m / min and the coating thickness is 15 μm; in step S3, the coating is first pre-cured at 120℃ for 5 minutes, and then cured at 160℃ for 10 minutes.

[0045] Example 3 A PP tape suitable for polymer soft-pack batteries includes a polypropylene carrier film and a composite adhesive layer.

[0046] The composite adhesive layer, by weight percentage, comprises the following components: 40% polypropylene carrier film, 30% epoxy-phenolic-silane hybrid adhesive layer, and nano-... - Montmorillonite barrier filler 5%, phosphorus and nitrogen intumescent flame retardant 8%, polybenzoxazole short fiber 6%, quaternary phosphonium salt corrosion inhibitor 1%, silane coupling agent 1%, antioxidant 0.5%.

[0047] The epoxy-phenolic-silane hybrid adhesive layer is prepared by crosslinking epoxy resin, phenolic resin and silane coupling agent, wherein the mass ratio of epoxy resin, phenolic resin and silane coupling agent is 5:4:2.

[0048] The nano - Montmorillonite barrier filler is prepared by surface modification of nano-silica and montmorillonite. The average particle size of the nano-silica is 100 nm, and the montmorillonite is organically modified with a lamellar spacing of 3.0 nm. The mass ratio of nano-silica to montmorillonite is 4:1.

[0049] The phosphorus-nitrogen intumescent flame retardant is composed of ammonium polyphosphate, pentaerythritol, and melamine in a mass ratio of 4:2:2.

[0050] The polybenzoxazole short fiber has a diameter of 20 μm, a length of 200 μm, and a tensile strength greater than 5.8 GPa.

[0051] The quaternary phosphonium salt corrosion inhibitor is triphenylbenzylphosphonium chloride.

[0052] The silane coupling agent is γ-methacryloxypropyltrimethoxysilane.

[0053] The thickness of the polypropylene carrier film is 50 μm, and the thickness of the composite adhesive layer is 30 μm.

[0054] The preparation method is the same as in Example 1, except that: in step S1, the speed of the high-speed disperser is 2500 rpm, the dispersion time is 30 minutes, and the dispersion temperature is 80℃; in step S2, the coating speed is 15 m / min and the coating thickness is 30 μm; in step S3, the material is first pre-cured at 140℃ for 3 minutes, and then cured at 180℃ for 5 minutes.

[0055] Comparative Example 1 The difference between this comparative example and Example 1 is that the composite adhesive layer does not contain nanoparticles. - Montmorillonite barrier filler, the corresponding component ratio is adjusted to 30% epoxy-phenolic-silane hybrid adhesive layer, 8% phosphorus-nitrogen intumescent flame retardant, 6% polybenzoxazole short fiber, 3% quaternary phosphonium salt corrosion inhibitor, 3% silane coupling agent, 1% antioxidant, and the content of the remaining components remains unchanged.

[0056] This comparative example lacks nanotechnology. - The montmorillonite barrier filler exhibited a significant decrease in barrier performance. After immersion in an electrolyte at 85°C for 1000 hours, the peel strength retention rate was only 63%, far lower than the 92% in Example 1.

[0057] Comparative Example 2 The difference between this comparative example and Example 1 is that the composite adhesive layer does not contain phosphorus-nitrogen intumescent flame retardants and polybenzoxazole short fibers, and the corresponding component ratio is adjusted to 35% epoxy-phenolic-silane hybrid adhesive layer, nano- - 15% montmorillonite barrier filler, 3% quaternary phosphorus salt corrosion inhibitor, 3% silane coupling agent, 1% antioxidant, with the content of the remaining components remaining unchanged.

[0058] Due to the lack of phosphorus-nitrogen intumescent flame retardant and polybenzoxazole short fiber, the flame retardant performance of this comparative example is significantly reduced, and the UL-94 test rating is only VTM-2, which cannot meet the battery safety requirements.

[0059] Comparative Example 3 The difference between this comparative example and Example 1 is that the composite adhesive layer does not contain quaternary phosphonium salt corrosion inhibitors and silane coupling agents, and the corresponding component ratio is adjusted to 30% epoxy-phenolic-silane hybrid adhesive layer, with nano- - 12% montmorillonite barrier filler, 8% phosphorus-nitrogen intumescent flame retardant, 6% polybenzoxazole short fiber, 1% antioxidant, with the content of the remaining components remaining unchanged.

[0060] Due to the lack of quaternary phosphorus salt corrosion inhibitor and silane coupling agent, the protective effect of this comparative example on the aluminum electrode post was significantly reduced. After being immersed in the electrolyte for 7 days, the aluminum electrode post showed obvious corrosion, with a corrosion area of ​​15%, which was much higher than the 2% in Example 1.

[0061] Performance testing To verify the performance advantages of the PP tape of the present invention, the PP tapes prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to the following performance tests, and the test results are shown in Table 1.

[0062] 1. Peel strength test: Referring to GB / T2792-2014 standard, the 180° peel strength of PP tape to PET film was tested using a universal testing machine.

[0063] 2. Peel strength retention test: The PP tape sample was placed in an electrolyte solution at 85°C ( After immersing in EC+DMC for 1000 hours, the peel strength after aging was tested, and the ratio of its strength to the initial strength was calculated.

[0064] 3. Heat shrinkage rate test: Cut the PP tape sample into standard size, heat it in an oven at 150°C for 30 minutes, measure its dimensional change, and calculate the shrinkage rate.

[0065] 4. Flame retardant performance test: The flame retardant rating is determined according to the VTM (Vertical Thin Material) test method in the UL-94 standard.

[0066] 5. DMT precipitation test: The electrolyte after soaking was analyzed by gas chromatography-mass spectrometry (GC-MS) to quantitatively detect the concentration of DMT.

[0067] 6. Aluminum electrode corrosion test: PP tape is attached to the surface of the aluminum electrode and immersed in electrolyte at 60°C for 7 days. The corrosion of the aluminum electrode is observed and the percentage of corrosion area is calculated.

[0068] 7. Test the adhesive strength of the CPP layer of aluminum-plastic film: PP tape is pasted on the CPP layer of aluminum-plastic film and a 90° peel test is performed to evaluate its adhesive performance.

[0069] Table 1 Performance Test Results

[0070] As can be seen from the test results in Table 1, the PP tapes of Examples 1-3 all exhibited excellent performance in all performance indicators. The peel strength retention rate was all greater than 90%, demonstrating excellent electrolyte resistance; the heat shrinkage rate was all less than 0.3%, demonstrating good dimensional stability; the flame retardant rating reached VTM-0, meeting battery safety requirements; DMT was not detected, proving excellent chemical stability; the corrosion area of ​​the aluminum electrode post was all less than 5%, demonstrating good corrosion inhibition performance; and the adhesion strength to the aluminum-plastic film CPP layer was all greater than 5 N / 25 mm, meeting the usage requirements.

[0071] In contrast, Comparative Example 1 lacks nanometers. - Montmorillonite barrier filler showed a significant decrease in barrier performance, with a peel strength retention rate of only 63%, far lower than the 92% in Example 1. Comparative Example 2, lacking phosphorus-nitrogen intumescent flame retardant and polybenzoxazole short fibers, exhibited a significant decrease in flame retardant performance, achieving a UL-94 test rating of only VTM-2, failing to meet battery safety requirements. Comparative Example 3, lacking quaternary phosphonium salt corrosion inhibitor and silane coupling agent, showed a significant decrease in protection for the aluminum electrode post, with a corrosion area reaching 15%, far exceeding the 2% in Example 1.

[0072] The above test results fully demonstrate that the present invention achieves multiple functions such as electrolyte resistance, high temperature resistance, flame retardancy and corrosion inhibition through the synergistic effect of each component. Each component is indispensable and together constitutes the core technical advantage of the present invention.

[0073] In summary, the embodiments of this application have at least the following technical effects: Compared with the prior art, this application firstly avoids the self-discharge problem caused by DMT generated from the degradation of PET in the electrolyte by using polypropylene as the substrate, resulting in excellent chemical stability. Secondly, this application achieves high-temperature stability and excellent adhesion performance through the design of the epoxy-phenolic-silane hybrid adhesive layer. Thirdly, this application utilizes nanotechnology... - Montmorillonite synergistically enhances the barrier properties of the tape. Furthermore, this application achieves excellent flame-retardant performance through the synergistic flame retardancy of phosphorus-nitrogen intumescent flame retardants and polybenzoxazole short fibers. Finally, this application constructs a self-healing passivation film through the synergistic effect of quaternary phosphonium salt corrosion inhibitors and silane coupling agents, effectively protecting the aluminum electrode posts. Thus, all the defects of traditional PET tapes are comprehensively solved, significantly improving the safety, reliability, and lifespan of polymer soft-pack batteries.

Claims

1. A PP tape suitable for polymer soft-pack batteries, characterized in that, Includes a polypropylene carrier membrane and a composite adhesive layer; The composite adhesive layer, by weight percentage, comprises the following components: 40-55% polypropylene carrier film, 20-30% epoxy-phenolic-silane hybrid adhesive layer, and nano-... - Montmorillonite barrier filler 5~12%, phosphorus and nitrogen intumescent flame retardant 3~8%, polybenzoxazole short fiber 2~6%, quaternary phosphonium salt corrosion inhibitor 1~4%, silane coupling agent 1~4%, antioxidant 0.5~2%; The epoxy-phenolic-silane hybrid adhesive layer is prepared by crosslinking epoxy resin, phenolic resin and silane coupling agent; The nano - Montmorillonite barrier filler is prepared by surface modification of nano-silica and montmorillonite; The thickness of the polypropylene carrier film is 25~50μm, and the thickness of the composite adhesive layer is 15~30μm.

2. The PP tape suitable for polymer soft-pack batteries according to claim 1, characterized in that, In the epoxy-phenolic-silane hybrid adhesive layer, the mass ratio of epoxy resin, phenolic resin and silane coupling agent is (3~5):(2~4):(1~2).

3. The PP tape suitable for polymer soft-pack batteries according to claim 1, characterized in that, The nano In the montmorillonite barrier filler, the average particle size of nano-silica is 20~100nm, and the montmorillonite is organically modified montmorillonite with a lamellar spacing of 1.5~3.0nm.

4. The PP tape suitable for polymer soft-pack batteries according to claim 1, characterized in that, The phosphorus-nitrogen intumescent flame retardant is composed of ammonium polyphosphate, pentaerythritol and melamine in a mass ratio of (2~4):(1~2):(1~2).

5. The PP tape suitable for polymer soft-pack batteries according to claim 1, characterized in that, The polybenzoxazole short fibers have a diameter of 10~20μm, a length of 50~200μm, and a tensile strength greater than 5.8GPa.

6. The PP tape suitable for polymer soft-pack batteries according to claim 1, characterized in that, The quaternary phosphonium salt corrosion inhibitor is at least one of tetrabutylphosphonium bromide, tetraphenylphosphonium bromide, or triphenylbenzylphosphonium chloride.

7. The PP tape suitable for polymer soft-pack batteries according to claim 1, characterized in that, The silane coupling agent is at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, or γ-methacryloyloxypropyltrimethoxysilane.

8. The PP tape suitable for polymer soft-pack batteries according to claim 1, characterized in that, The antioxidant is at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris[2,4-di-tert-butylphenyl]phosphite, or octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

9. The PP tape suitable for polymer soft-pack batteries according to claim 1, characterized in that, The quaternary phosphorus salt corrosion inhibitor is encapsulated using microencapsulation technology. The microcapsule particle size is 10~50μm, and the wall material is polyaniline or urea-formaldehyde resin.

10. A method for preparing a PP tape suitable for polymer soft-pack batteries according to any one of claims 1 to 12, characterized in that, Includes the following steps: S1: Weigh each component raw material according to the formula ratio, and combine the epoxy-phenolic-silane hybrid adhesive layer and nano- - Montmorillonite barrier filler, phosphorus and nitrogen intumescent flame retardant, polybenzoxazole short fiber, quaternary phosphonium salt corrosion inhibitor, silane coupling agent and antioxidant are added to a high-speed disperser and dispersed at 1500-2500 rpm for 30-60 minutes at 60-80℃ to obtain composite adhesive slurry. The high-speed disperser has a rotation speed of 2000 rpm, a dispersion time of 45 minutes, and a dispersion temperature of 70℃. S2: The composite adhesive slurry obtained in step S1 is uniformly coated onto the surface of the polypropylene carrier film using a precision coating method. The coating speed is 5~15m / min and the coating thickness is 15~30μm. S3: The polypropylene carrier film coated with the composite adhesive layer obtained in step S2 is sent into a hot air circulating oven for heat curing treatment. The curing temperature is 120~180℃ and the curing time is 5~15 minutes. The thermosetting process employs a segmented curing method: first, pre-curing at 120~140℃ for 3~5 minutes, followed by main curing at 160~180℃ for 5~10 minutes. S4: The PP tape cured in step S3 is cooled to room temperature by a cooling roller, wound up under constant tension, and then cut and packaged to obtain the PP tape.

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