High-heat-resistance aluminum-plastic film for low-temperature soft-package lithium battery and preparation method of high-heat-resistance aluminum-plastic film

Abstract

The invention belongs to the technical field of aluminum-plastic film manufacturing, and particularly relates to a high-heat-resistance type aluminum-plastic film for a low-temperature soft package lithium battery and a preparation method of the high-heat-resistance type aluminum-plastic film, and the high-heat-resistance type aluminum-plastic film comprises an outer protective layer, a third adhesive layer, a heat-resistance enhancement layer, a second adhesive layer, an aluminum foil barrier layer, a first adhesive layer and an inner heat sealing layer which are sequentially stacked from outside to inside; wherein the heat-resistant enhancement layer is a nano aerogel-aluminized PET (polyethylene terephthalate) composite film, the nano aerogel is flexible silicon-based aerogel, and the thickness of an aluminum layer of the aluminized PET is 50-200nm; and the surface of the aluminum foil barrier layer is subjected to micro-arc oxidation treatment to form a porous Al2O3 layer with the thickness of 5-10 microns.

Description

Technical Field

[0001] This invention belongs to the field of aluminum-plastic film manufacturing technology, specifically relating to a high heat-resistant aluminum-plastic film for low-temperature soft-pack lithium batteries and its preparation method. Background Technology

[0002] With the widespread application of lithium-ion batteries in electric vehicles, outdoor energy storage devices, and cryogenic medical devices, pouch batteries have captured a significant market share due to their advantages such as high energy density, small size, and light weight. Aluminum-plastic film, as a key packaging material for pouch batteries, directly affects the battery's safety, stability, and lifespan.

[0003] Currently, there are many types of aluminum-plastic films on the market. Traditional aluminum-plastic films mainly consist of an outer protective layer, an adhesive layer, an aluminum foil barrier layer, and an inner heat-sealing layer. While they can meet basic requirements such as oxygen barrier, water barrier, and resistance to electrolyte corrosion, their heat insulation performance in low-temperature environments is poor. In low-temperature environments ranging from -40℃ to 0℃, traditional aluminum-plastic films have high thermal conductivity, typically between 0.12 and 0.15 W / (m·K), causing heat to easily escape from the battery's interior, severely affecting the battery's capacity retention and cycle life. Simultaneously, the outer PA and inner PP layers used in traditional aluminum-plastic films are prone to embrittlement at low temperatures, resulting in reduced elongation at break, which may lead to film cracking and affect the battery's sealing and safety. Furthermore, the aluminum foil in traditional aluminum-plastic films itself has high thermal conductivity (approximately 237 W / (m·K)), and the heat conduction paths between the layers are not effectively blocked, further exacerbating the heat transfer problem.

[0004] Therefore, overcoming the deficiency of insufficient thermal resistance performance of pouch batteries in low-temperature environments is a technical problem that urgently needs to be solved in this field.

[0005] It should be noted that the information disclosed in this background section is only for understanding the background technology of the present application concept, and therefore, the above description is not considered to constitute prior art information. Summary of the Invention

[0006] This disclosure provides at least one high-heat-resistance aluminum-plastic film for low-temperature soft-pack lithium batteries and its preparation method.

[0007] In a first aspect, embodiments of this disclosure provide a high heat-resistant aluminum-plastic film for low-temperature soft-pack lithium batteries, comprising, from the outside to the inside, an outer protective layer, a third adhesive layer, a heat-resistant reinforcing layer, a second adhesive layer, an aluminum foil barrier layer, a first adhesive layer, and an inner heat-sealing layer stacked sequentially; wherein, the heat-resistant reinforcing layer is a nano-aerogel-aluminized PET composite film, the nano-aerogel is a flexible silicon-based aerogel, and the aluminum layer thickness of the aluminized PET is 50-200 nm; the surface of the aluminum foil barrier layer is subjected to micro-arc oxidation treatment to form a porous Al2O3 layer with a thickness of 5-10 μm.

[0008] In one optional embodiment, the outer protective layer is a modified low-temperature resistant nylon, comprising a cold-resistant toughening agent and nano-SiO2 low thermal conductivity filler; the thickness of the outer protective layer is 25–30 μm.

[0009] In one optional embodiment, the third adhesive layer is a low-temperature curing polyurethane adhesive with a thickness of 3–5 μm.

[0010] In one optional embodiment, the thickness of the heat-resistant reinforcement layer is 10–15 μm.

[0011] In one optional embodiment, the first adhesive layer and the second adhesive layer are epoxy-silicone hybrid adhesives with a thickness of 3 to 5 μm.

[0012] In one optional embodiment, the aluminum foil barrier layer is an ultra-thin high-purity aluminum foil with a purity of not less than 99.9% and a thickness of 40–50 μm.

[0013] In one optional embodiment, the inner heat-sealing layer is a modified low-temperature resistant PP, comprising ethylene-propylene comonomer and low thermal conductivity calcium carbonate microparticles, with a thickness of 50–60 μm.

[0014] Secondly, this disclosure also provides a method for preparing a high-heat-resistant aluminum-plastic film for low-temperature soft-pack lithium batteries as described above, comprising: adding 8%–12% ethylene-propylene copolymer monomer and 5%–8% low-thermal-conductivity calcium carbonate microparticles, and 0.3%–0.5% maleic anhydride graft to polypropylene by mass percentage; extruding the film through a die to obtain an inner heat-sealing layer; thoroughly cleaning the aluminum foil, followed by micro-arc oxidation treatment to form a porous Al2O3 layer, thereby obtaining an aluminum foil barrier layer; selecting PET film as a substrate, and depositing a dense aluminum layer on the surface after corona treatment to form an aluminized PET film with a metallized barrier layer, and then combining it with a film prepared by a sol-gel method. The obtained flexible silicone-based aerogel film is hot-pressed to form a heat-resistant reinforcing layer; 5%–8% cold-resistant toughening agent, 8%–12% ethylene-octene copolymer and 3%–5% nano-SiO2 low thermal conductivity filler are added to nylon by mass percentage, and the film is extruded by a die to obtain an outer protective layer; the inner heat-sealing layer and aluminum foil barrier layer are composited with epoxy-organic silicone hybrid adhesive to obtain a first composite layer, and then the outer protective layer and aluminum foil barrier layer are composited with low-temperature curing polyurethane adhesive to obtain a second composite layer. The first composite layer and the second composite layer are composited again with epoxy-organic silicone hybrid adhesive, and cured and crosslinked to obtain a high heat-resistant aluminum-plastic film for low-temperature soft-pack lithium batteries.

[0015] In one alternative embodiment, the thorough cleaning of the aluminum foil includes alkaline washing, acid washing, and rinsing with pure water.

[0016] Thirdly, embodiments of this disclosure also provide a high heat-resistant aluminum-plastic film for low-temperature soft-pack lithium batteries as described above.

[0017] The beneficial effects of this invention are as follows: the high thermal resistance aluminum-plastic film for low-temperature soft-pack lithium batteries and its preparation method block heat conduction and reflect infrared thermal radiation through the nano-aerogel porous structure of the thermal resistance enhancement layer and the aluminum plating layer. Combined with the micro-arc oxidation treatment of the aluminum foil layer, the thermal conductivity of the aluminum-plastic film is reduced to 0.04-0.06 W / (m·K), significantly reducing the loss of heat from the battery to the external low-temperature environment. Combined with the innovative seven-layer composite structure and material selection, it has significant advantages in terms of thermal resistance performance, low-temperature adaptability and compatibility. It can effectively ensure the performance stability of soft-pack batteries under cold conditions, providing a reliable material solution for the low-temperature application of soft-pack batteries, and is expected to fill the market gap for high thermal resistance performance of aluminum-plastic films for soft-pack batteries in low-temperature environments.

[0018] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of a high heat-resistant aluminum-plastic film for low-temperature soft-pack lithium batteries provided in an embodiment of this disclosure.

[0022] In the picture:

[0023] 1. Outer protective layer; 2. Third adhesive layer; 3. Heat-insulating reinforcing layer; 4. Second adhesive layer; 5. Aluminum foil barrier layer; 6. First adhesive layer; 7. Inner heat-sealing layer. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.

[0026] In this document, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. As used herein, expressions such as “at least one of…” modify the entire list of elements when following a list of elements, rather than individual elements in the list. For example, the expression “at least one of a, b, and c” should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0027] The terminology used herein is for the purpose of describing specific exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may also be intended to include plural forms unless otherwise clearly stated herein. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. Additional or alternative steps may be employed.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0030] This disclosure provides a high heat-resistant aluminum-plastic film for low-temperature soft-pack lithium batteries, comprising, from the outside to the inside, an outer protective layer, a third adhesive layer, a heat-resistant reinforcing layer, a second adhesive layer, an aluminum foil barrier layer, a first adhesive layer, and an inner heat-sealing layer, stacked sequentially. The heat-resistant reinforcing layer is a nano-aerogel-aluminized PET composite film. The nano-aerogel is a flexible silicon-based aerogel, avoiding brittleness issues. Its porous structure (containing still air, thermal conductivity <0.02 W / (m·K)) can block heat conduction. The aluminum layer of the aluminized PET has a thickness of 50–200 nm and can reflect infrared thermal radiation. The combination of these two elements reduces the thermal conductivity of this layer to below 0.03 W / (m·K). The surface of the aluminum foil barrier layer is treated with micro-arc oxidation to form a porous Al2O3 layer with a thickness of 5–10 μm. The low thermal conductivity (approximately 30 W / (m·K)) and porous structure of the oxide layer extend the heat transfer path, reducing the overall heat conduction efficiency.

[0031] In some embodiments, specifically, the outer protective layer is a modified low-temperature resistant nylon, including a cold-resistant toughening agent and nano-SiO2 low thermal conductivity filler, which can improve its puncture resistance, impact resistance, and weather resistance, while reducing heat conduction; the thickness of the outer protective layer is 25-30 μm.

[0032] In some embodiments, specifically, the third adhesive layer is a low-temperature curing polyurethane adhesive used to bond the outer protective layer and the heat-insulating reinforcement layer, and does not become brittle at low temperatures. The adhesive layer molecular chains introduce flexible segments, which can reduce thermal conductivity, and the thickness is 3 to 5 μm.

[0033] In some embodiments, specifically, the thickness of the heat-resistant reinforcement layer is 10–15 μm.

[0034] In some embodiments, specifically, the first adhesive layer and the second adhesive layer are epoxy-silicone hybrid adhesives used to bond the heat-insulating reinforcement layer and the aluminum foil barrier layer. They have excellent bonding strength, high and low temperature stability and chemical inertness. At the same time, the adhesive layer has low thermal conductivity and forms a gradient heat-insulating structure with the heat-insulating reinforcement layer, further reducing the overall heat conduction efficiency. The thickness is 3 to 5 μm.

[0035] In some embodiments, specifically, the aluminum foil barrier layer is an ultra-thin high-purity aluminum foil with a purity of not less than 99.9% and a thickness of 40-50 μm, which plays a core barrier function of preventing oxygen and water.

[0036] In some embodiments, specifically, the inner heat-sealing layer is a modified low-temperature resistant PP, comprising ethylene-propylene comonomer and low thermal conductivity calcium carbonate microparticles. The introduction of elastic segments can reduce crystallinity, improve heat-sealing properties, resistance to electrolyte corrosion, and low-temperature flexibility. The addition of 0.5% maleic anhydride grafts can improve adhesion to aluminum foil and stability against carbonate electrolytes. The thickness is 50-60 μm.

[0037] Specifically, the high heat resistance soft-pack battery aluminum-plastic film prepared according to the above requirements has a thermal conductivity of 0.04~0.06W / (m·K), an elongation at break of >200% at -40℃, a heat sealing strength of >30N / 15mm, and a heat sealing temperature controlled at 180~200℃, and is compatible with traditional processes.

[0038] This disclosure also provides a method for preparing a high-heat-resistant aluminum-plastic film for low-temperature soft-pack lithium batteries as described above, comprising: adding 8%–12% ethylene-propylene copolymer monomer and 5%–8% low-thermal-conductivity calcium carbonate microparticles, and 0.3%–0.5% maleic anhydride graft to polypropylene by mass percentage; extruding the film through a die to obtain an inner heat-sealing layer; thoroughly cleaning the aluminum foil, followed by micro-arc oxidation treatment to form a porous Al2O3 layer, obtaining an aluminum foil barrier layer; selecting PET film as a substrate, and depositing a dense aluminum layer on the surface after corona treatment to form an aluminized PET film with a metallized barrier layer; subsequently, combining the film with a flexible aluminum-plastic film prepared by the sol-gel method. A thermally insulating and reinforcing layer is obtained by hot-pressing a silicone-based aerogel film. 5%–8% of a cold-resistant toughening agent, 8%–12% of an ethylene-octene copolymer, and 3%–5% of nano-SiO2 low thermal conductivity filler are added to nylon by mass percentage, and the film is extruded through a die to obtain an outer protective layer. An epoxy-silicone hybrid adhesive is used to bond the inner heat-sealing layer and the aluminum foil barrier layer to obtain a first composite layer. Subsequently, a low-temperature curing polyurethane adhesive is used to bond the outer protective layer and the aluminum foil barrier layer to obtain a second composite layer. Finally, an epoxy-silicone hybrid adhesive is used to bond the first composite layer and the second composite layer, followed by curing and cross-linking treatment to obtain a high thermally insulating aluminum-plastic film for low-temperature soft-pack lithium batteries.

[0039] In some embodiments, specifically, the thorough cleaning of the aluminum foil includes alkaline washing, acid washing, and rinsing with pure water.

[0040] This disclosure also provides a high heat-resistant aluminum-plastic film for low-temperature soft-pack lithium batteries as described above.

[0041] Example 1

[0042] (1) Preparation of the inner heat-sealing layer: Modified low-temperature resistant PP film was prepared using a casting method. 8%–12% of ethylene-propylene comonomer and 5%–8% of low thermal conductivity calcium carbonate microparticles (CaCO3, particle size 1–3 μm) and 0.3%–0.5% maleic anhydride grafts were added to the polypropylene (PP) raw material as compatibilizers. The raw materials were mixed evenly and extruded through a die to form an inner heat-sealing layer film with a thickness of 50–60 μm, which was then wound up for later use.

[0043] (2) Aluminum foil barrier layer treatment: Ultra-thin aluminum foil with a purity of 99.9% and a thickness of 40–50 μm was selected. The aluminum foil underwent a three-stage cleaning process (alkali washing, acid washing, and pure water rinsing) to remove surface oil and impurities, followed by micro-arc oxidation treatment to form a porous Al2O3 layer with a thickness of 5–10 μm on the aluminum foil surface. After treatment, the surface tension of the aluminum foil was ≥72 dyn / cm, providing an ideal substrate for subsequent bonding.

[0044] (3) Preparation of the heat-insulating reinforcement layer: A PET film with a thickness of 5-10 μm was selected as the substrate. After corona treatment to improve surface activity, it was sent to a vacuum coating machine to deposit a dense aluminum layer with a thickness of 50-200 nm on its surface, forming a metallized barrier layer. Subsequently, the aluminized PET film was composited with a flexible silicon-based aerogel film with a thickness of 5-10 μm prepared by the sol-gel method through a hot-pressing process to form a heat-insulating reinforcement layer, the total thickness of which was controlled within the range of 10-20 μm.

[0045] (4) Preparation of the outer protective layer: The modified low-temperature resistant nylon film was also prepared by casting. 5% to 8% of a cold-resistant toughening agent, ethylene-octene copolymer (POE), and 3% to 5% of nano-SiO2 low thermal conductivity filler (particle size 20 to 50 nm) were added to the nylon (PA) raw material. The raw materials were mixed evenly and extruded through a die to form an outer protective film with a thickness of 25 to 30 μm, which was then wound up for later use.

[0046] (5) Composite and Curing: A high-heat-resistant aluminum-plastic film was prepared layer by layer using a dry composite process. First, an epoxy-silicone hybrid adhesive was used to composite the inner heat-sealing layer with the aluminum foil barrier layer. Then, a low-temperature curing polyurethane adhesive was used to composite the outer protective layer with the heat-resistant reinforcing layer. Afterward, the two composite layers were composited again using an epoxy-silicone hybrid adhesive to obtain a high-performance aluminum-plastic film with a multi-layer synergistic heat-resistant structure, with a total thickness controlled between 130 and 175 μm. After composite, the aluminum-plastic film was sent to a curing chamber for curing treatment to ensure that the adhesives in each layer are fully cross-linked, ensuring interlayer bonding strength and overall structural stability.

[0047] Performance testing

[0048] Low-temperature performance test: After placing the aluminum-plastic film in an environment of -40℃ for 24 hours, test its elongation at break. The elongation at break is required to be >200%. At the same time, conduct a heat seal strength test. The heat seal temperature is controlled at 180~200℃ and the heat seal time is 1-2s. The heat seal strength is required to be >30N / 15mm.

[0049] Thermal resistance test: An aluminum-plastic film was used to seal a 100×100mm empty bag, and a T-type thermocouple was placed inside. After stabilizing in an environment of -40℃ for 2 hours, the temperature difference between the inside and outside of the bag was recorded. The requirement was that ΔT ≥ 7℃ (compared to only 2℃ for traditional materials).

[0050] Thermal conductivity test: The thermal conductivity of the aluminum-plastic film is measured using the steady-state heat flow method or the laser flash method. The thermal conductivity is required to be in the range of 0.04 to 0.06 W / (m·K).

[0051] Table 1. Performance test results of high heat resistance aluminum-plastic film

[0052] project Example 1 Example 2 Example 3 Example 4 Example 5 Total thickness of the thermal insulation reinforcement layer (μm) 12 15 12 12 12 Micro-arc oxidation layer (μm) on aluminum foil 7 7 10 7 7 Inner layer PP comonomer (%) 10 10 10 12 10 Outer layer PA cold-resistant toughening agent (%) 7 7 7 7 8 Thermal conductivity W / (m·K) 0.05 0.043 0.045 0.05 0.048 Thermal resistance performance ΔT (°C) 8 8.7 8.3 8 8.5 Elongation at break (-40℃) 220 215 220 235 225 Heat seal strength (N / 15mm) 31 31 31 35 31

[0053] Specifically, in each embodiment, the thickness of the inner heat-sealing layer is 55 μm; the thickness of the aluminum foil barrier layer is 45 μm; and the thickness of the outer protective layer is 27 μm.

[0054] Specifically, as shown in Table 1, the high heat-resistant aluminum-plastic film for low-temperature soft-pack lithium batteries obtained in Examples 1-5 blocks heat conduction through the nano-aerogel porous structure of the heat-resistant reinforcement layer and reflects infrared thermal radiation through the aluminum plating layer. Combined with the micro-arc oxidation treatment of the aluminum foil layer, the thermal conductivity of the aluminum-plastic film is reduced to 0.04-0.06 W / (m·K), which significantly reduces the loss of heat from the battery to the external low-temperature environment.

[0055] Specifically, the aluminum-plastic film of the present invention has excellent low-temperature adaptability; both the outer PA layer and the inner PP layer are copolymerized and modified, and still maintain an elongation at break of >200% at -40℃, avoiding the risk of cracking caused by low-temperature embrittlement. The adhesion and stability of each layer material are good at low temperatures.

[0056] Specifically, the aluminum-plastic film of the present invention is compatible with battery characteristics; it does not affect the basic functions of the pouch battery, meets the mechanical and chemical stability requirements during the battery charging and discharging process, and can be directly adapted to existing pouch battery production lines without adjusting equipment parameters such as heat sealing and cutting.

[0057] In summary, this high-heat-resistant aluminum-plastic film for low-temperature pouch lithium batteries and its preparation method utilize the nano-aerogel porous structure of the heat-resistant reinforcement layer to block heat conduction and the aluminum plating layer to reflect infrared thermal radiation. Combined with the micro-arc oxidation treatment of the aluminum foil layer, the thermal conductivity of the aluminum-plastic film is reduced to 0.04–0.06 W / (m·K), significantly reducing the loss of internal battery heat to the external low-temperature environment. Combined with the innovative seven-layer composite structure and material selection, it exhibits significant advantages in heat resistance, low-temperature adaptability, and compatibility, effectively ensuring the performance stability of pouch batteries under cold conditions. This provides a reliable material solution for the low-temperature application of pouch batteries and is expected to fill the market gap for high-heat-resistant aluminum-plastic films for pouch batteries in low-temperature environments.

[0058] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A high thermal resistance aluminum-plastic film for low-temperature soft-pack lithium batteries, characterized in that, From the outside to the inside, it includes an outer protective layer, a third adhesive layer, a heat-insulating and reinforcing layer, a second adhesive layer, an aluminum foil barrier layer, a first adhesive layer, and an inner heat-sealing layer, which are stacked in sequence. The heat-resistant reinforcing layer is a nano-aerogel-aluminized PET composite film, wherein the nano-aerogel is a flexible silicon-based aerogel, and the aluminum layer thickness of the aluminized PET is 50-200 nm. The surface of the aluminum foil barrier layer is subjected to micro-arc oxidation treatment to form a porous Al2O3 layer with a thickness of 5-10 μm.

2. The high thermal resistance aluminum-plastic film for low-temperature soft-pack lithium batteries as described in claim 1, characterized in that, The outer protective layer is a modified low-temperature resistant nylon, including a cold-resistant toughening agent and nano-SiO2 low thermal conductivity filler; The thickness of the outer protective layer is 25–30 μm.

3. The high thermal resistance aluminum-plastic film for low-temperature soft-pack lithium batteries as described in claim 1, characterized in that, The third adhesive layer is a low-temperature curing polyurethane adhesive with a thickness of 3-5 μm.

4. The high thermal resistance aluminum-plastic film for low-temperature soft-pack lithium batteries as described in claim 1, characterized in that, The thickness of the heat-insulating reinforcement layer is 10–15 μm.

5. The high thermal resistance aluminum-plastic film for low-temperature soft-pack lithium batteries as described in claim 1, characterized in that, The first adhesive layer and the second adhesive layer are epoxy-silicone hybrid adhesives with a thickness of 3 to 5 μm.

6. The high thermal resistance aluminum-plastic film for low-temperature soft-pack lithium batteries as described in claim 1, characterized in that, The aluminum foil barrier layer is an ultra-thin, high-purity aluminum foil with a purity of not less than 99.9% and a thickness of 40–50 μm.

7. The high thermal resistance aluminum-plastic film for low-temperature soft-pack lithium batteries as described in claim 1, characterized in that, The inner heat-sealing layer is a modified low-temperature resistant PP, comprising ethylene-propylene comonomer and low thermal conductivity calcium carbonate microparticles, with a thickness of 50-60 μm.

8. A method for preparing a high thermal resistance aluminum-plastic film for low-temperature soft-pack lithium batteries as described in any one of claims 1-7, characterized in that, include: Add 8%–12% ethylene-propylene comonomer, 5%–8% low thermal conductivity calcium carbonate microparticles, and 0.3%–0.5% maleic anhydride grafts to polypropylene by mass percentage, and extrude the mixture through a die to form a film to obtain the inner heat-sealing layer. The aluminum foil is thoroughly cleaned and then subjected to micro-arc oxidation treatment to form a porous Al2O3 layer, thus obtaining the aluminum foil barrier layer. PET film is selected as the substrate. After corona treatment, a dense aluminum layer is deposited on the surface to form an aluminum-plated PET film with a metallized barrier layer. Then, it is hot-pressed and laminated with a flexible silicon-based aerogel film prepared by sol-gel method to obtain a heat-insulating reinforcement layer. Add 5%–8% cold-resistant toughening agent, 8%–12% ethylene-octene copolymer and 3%–5% nano-SiO2 low thermal conductivity filler to nylon by mass percentage, and extrude the film with a die to obtain an outer protective layer. A first composite layer is obtained by bonding an inner heat-sealing layer and an aluminum foil barrier layer with an epoxy-silicone hybrid adhesive. Then, a second composite layer is obtained by bonding an outer protective layer and an aluminum foil barrier layer with a low-temperature curing polyurethane adhesive. The first composite layer and the second composite layer are then bonded together with an epoxy-silicone hybrid adhesive and cured and crosslinked to obtain a high heat-resistant aluminum-plastic film for low-temperature soft-pack lithium batteries.

9. The preparation method according to claim 8, characterized in that, The thorough cleaning of the aluminum foil includes alkaline washing, acid washing, and rinsing with pure water.

10. A lithium-ion battery, characterized in that, The high heat-resistant aluminum-plastic film for low-temperature soft-pack lithium batteries as described in any one of claims 1-7 is used.

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