An aluminum-plastic film and battery

Abstract

This invention belongs to the field of battery technology and mainly relates to an aluminum-plastic film, including two symmetrically arranged perforations, a top sealing area along one side of the perforation width direction, and a side sealing area along the perforation length direction. The side sealing area and / or the top sealing area are sequentially configured with a nylon layer, an aluminum foil layer, a hot melt adhesive layer, and a low-melting-point adhesive layer along their thickness direction. The nylon layer and the aluminum foil layer are bonded together by an adhesive layer, and the aluminum foil layer and the hot melt adhesive layer are bonded together by an adhesive layer. The length of the low-melting-point adhesive layer is less than or equal to the length of the side sealing area and the top sealing area. The low-melting-point adhesive layer is applied to the surface of the hot melt adhesive layer in a segmented or continuous coating manner. The melting point of the hot melt adhesive layer is 140℃-170℃, and the melting point of the low-melting-point adhesive layer is 90℃-130℃. This allows the battery prepared from the aluminum-plastic film of this application to maintain thermal stability while preserving battery performance. Furthermore, this application prepares a battery that improves battery performance.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to an aluminum-plastic film and a battery. Background Technology

[0002] Since their commercialization, batteries have been widely used in consumer electronics, electric vehicles, and energy storage due to their high energy density, high power density, excellent cycle performance, low self-discharge rate, and environmental friendliness. However, with rapid technological advancements, battery products are gradually evolving towards faster charging rates and higher voltages. While these technological upgrades improve battery performance, they also significantly increase the risk of thermal instability in high-temperature environments.

[0003] Hot chamber testing is a crucial method for evaluating battery thermal stability. According to the national standard GB31241, batteries must pass a hot chamber test at 130℃ for 30 minutes to verify their safety and reliability under high-temperature conditions. Under these test conditions, if the battery experiences sealing failure or excessive internal pressure due to high temperature, it may lead to safety issues such as fire or explosion. Therefore, the main purpose of hot chamber testing is to simulate battery performance under extreme temperature conditions, verify battery safety, and thus ensure that it meets the safety requirements for practical applications.

[0004] Existing technologies primarily improve battery stability at high temperatures by altering the battery material system, including the positive electrode material, negative electrode material, separator, electrolyte, and aluminum-plastic film, thereby reducing gas generation inside the battery at high temperatures. While this adjustment of the material system can significantly improve the battery's thermal performance, it often adversely affects the battery's charging performance or capacity. For example, improving the thermal stability of the positive or negative electrode material may sacrifice the battery's energy density; adjusting the thermal stability of the separator may affect lithium-ion transport efficiency, thus reducing the battery's charging rate or capacity. Therefore, existing technologies suffer from a technical drawback: an inability to balance improving thermal performance with maintaining battery performance.

[0005] Therefore, it is urgent to improve existing aluminum-plastic films and batteries to solve the above-mentioned technical defects. Summary of the Invention

[0006] One of the objectives of this invention is to provide an aluminum-plastic film that can maintain thermal stability while preserving battery performance, addressing the shortcomings of existing technologies.

[0007] To achieve the above technical objectives, this application implements the following technical solution:

[0008] An aluminum-plastic film includes two symmetrically arranged ground craters, a top sealing area arranged on one side along the width direction of the crater, and a side sealing area arranged along the length direction of the crater.

[0009] The side sealing area and / or top sealing area are sequentially configured with a nylon layer, an aluminum foil layer, a hot melt adhesive layer, and a low melting point adhesive layer along their thickness direction. The nylon layer and the aluminum foil layer are bonded together by an adhesive layer, and the aluminum foil layer and the hot melt adhesive layer are bonded together by an adhesive layer. The length of the low melting point adhesive layer is less than or equal to the length of the side sealing area and the top sealing area. At the same time, the low melting point adhesive layer is applied to the surface of the hot melt adhesive layer in a segmented coating or continuous coating manner.

[0010] The melting point of the hot melt adhesive layer is 140℃-170℃, and the melting point of the low melting point adhesive layer is 90℃-130℃.

[0011] The above technical solution produces the following technical effects:

[0012] This application proposes an innovative technical solution based on an aluminum-plastic film encapsulation structure. By coating or pasting a low-melting-point adhesive layer at the aluminum-plastic film seal, this low-melting-point adhesive layer melts within its melting point range under high-temperature conditions, reducing the sealing performance of the aluminum-plastic film seal. When a large amount of gas and heat is generated inside the battery due to high temperature, this gas and heat can be quickly discharged through the molten seal area, thereby effectively alleviating the pressure buildup inside the battery and avoiding safety problems such as fire or explosion caused by excessive internal pressure.

[0013] Compared to existing technologies, the technical solution of this application does not involve any modification to the battery material system, including the positive electrode, negative electrode, separator, and electrolyte, and therefore has no impact on the battery's charging capability and capacity. Simultaneously, by adding a low-melting-point polymer adhesive layer to the aluminum-plastic film sealing area, rapid pressure relief under high-temperature conditions can be achieved, significantly improving the battery's thermal performance. This method improves the battery's thermal stability while also meeting its high-performance requirements, thus resolving the technical deficiency of existing technologies that affect battery performance when improving thermal performance.

[0014] As a further improvement to the aluminum-plastic film of this application, the low-melting-point adhesive layer is prepared by blending a first polymer and a second polymer. The first polymer is a mixture of polyethylene and polypropylene, and the second polymer is a modified polymer used to modify the melting point of the low-melting-point adhesive layer.

[0015] As a further improvement to the aluminum-plastic film of this application, the polyethylene has a number average molecular weight of 80,000-120,000 and a melting point of 85℃-125℃.

[0016] Polypropylene has a number average molecular weight of 40,000-100,000 and a melting point of 100℃-160℃.

[0017] As a further improvement to the aluminum-plastic film of this application, the mass ratio of polyethylene to polypropylene in the low-melting-point adhesive layer is 0-1:0-1.

[0018] As a further improvement to the aluminum-plastic film of this application, the second polymer is composed of one or more of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, polymethyl methacrylate, acrylonitrile-butadiene-styrene, polylactic acid, polyvinyl chloride, polyvinyl butyral, polyacrylonitrile, or polyvinylidene fluoride.

[0019] As a further improvement to the aluminum-plastic film of this application, the mass ratio of the first polymer to the second polymer is 1:0-0.2.

[0020] As a further improvement to the aluminum-plastic film of this application, the thickness of the hot melt adhesive layer is C, and the thickness of the low melting point adhesive layer is e, wherein C and e satisfy 0.2≤C / e.

[0021] As a further improvement to the aluminum-plastic film of this application, the top sealing area is provided with a first sealing area, and the side sealing area is provided with a second sealing area; the width of the top sealing area and the side sealing area is a, the width of the first sealing area and the second sealing area is b, and the width of the low melting point adhesive layer is B.

[0022] Among them, a, b and B satisfy b≤B≤a.

[0023] The second objective of this invention is to provide a battery that can maintain thermal stability while preserving battery performance, addressing the shortcomings of existing technologies.

[0024] To achieve the above technical objectives, this application implements the following technical solution:

[0025] A battery includes an aluminum-plastic film as described above and a battery cell disposed in two perforations in the aluminum-plastic film; the battery cell extends to be provided with tabs, and the tabs are bonded to the top sealing area by tab adhesive layer.

[0026] The above technical solution produces the following technical effects:

[0027] By employing the aluminum-plastic film of this invention, the battery exhibits better thermal stability under high-temperature conditions while maintaining its charging performance and capacity. Due to the presence of the low-melting-point adhesive layer 124, the battery can effectively release internal pressure under high-temperature conditions, avoiding safety issues caused by excessive pressure.

[0028] As a further improvement to a battery of this application, the length of the low melting point adhesive layer of the aluminum-plastic film is A, the width of the battery is c, and the length of the battery is d. When the low melting point adhesive layer is segmented, the length A of the low melting point adhesive layer represents the length of each segment of the low melting point adhesive layer, and the number of segments of the low melting point adhesive layer is n. When the low melting point adhesive layer is continuously coated, the number of time segments n=1.

[0029] Among them, A, c, d, and n satisfy 0.02≤n*A / c or n*A / d≤1. Attached Figure Description

[0030] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0031] Figure 1 This is a cross-sectional view of the aluminum-plastic film along the thickness direction in this invention;

[0032] Figure 2 This is a top view of the aluminum-plastic film in this invention;

[0033] Figure 3 for Figure 2 A magnified view of a portion at point A;

[0034] Figure 4 This is a schematic diagram of the battery structure of the present invention;

[0035] in:

[0036] 100-Aluminum-Plastic Film;

[0037] 11-Flush the hole;

[0038] 12-Top Sealing Area;

[0039] 121 - Nylon layer;

[0040] 122 - Nylon layer;

[0041] 123 - Hot melt adhesive layer;

[0042] 124 - Low melting point adhesive layer;

[0043] 125 - First Sealed Zone

[0044] 13-Side sealing area;

[0045] 131 - Second Sealed Zone;

[0046] 2-cell

[0047] 21-Ear;

[0048] 211 - Ear gel. Detailed Implementation Detailed Implementation

[0050] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this application.

[0051] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0052] Although this application discloses preferred embodiments as described above, it is not intended to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.

[0053] In existing technologies, it is known that the principle of hot-box testing is to place the battery in a high-temperature environment to simulate battery performance under extreme temperature conditions. If the battery experiences sealing failure or excessive internal pressure at high temperatures, it may lead to safety issues. Therefore, hot-box testing is one of the important methods for evaluating battery thermal stability. However, while existing technologies improve battery thermal stability, they often adversely affect the battery's charging performance or capacity.

[0054] Specifically, the hot box testing process involves fully charging the battery, placing it in a hot box, raising the temperature to a specific level, maintaining it for a certain period, and then observing whether the battery catches fire. The national standard GB31241 stipulates that batteries must pass a hot box test at 130℃ for 30 minutes. However, the hot melt temperature of the hot melt adhesive layer 123 used in traditional battery aluminum-plastic film 100 is generally between 140℃ and 170℃. This may not melt in time under high-temperature conditions, resulting in the inability to effectively release internal battery pressure. This application addresses the technical deficiencies in the existing hot box testing process by incorporating a sealing layer with a temperature below 130℃ during the aluminum-plastic film 100 sealing process. This sealing layer can be smaller than the top sealing area 12 or the side sealing area 13. This allows for openings during the hot box testing process, enabling the gas and heat generated inside the battery to quickly escape through the molten sealing area, effectively alleviating internal pressure buildup and preventing damage to the battery due to excessive internal pressure.

[0055] like Figure 1-4 As shown, in order to solve the technical defect of excessive internal pressure of the battery due to the sealing of the aluminum-plastic film 100 during the hot box testing process in the prior art, this application provides an aluminum-plastic film 100, including two symmetrically arranged perforations 11, a top sealing area 12 arranged on one side along the width direction (X-axis direction) of the perforation 11, and a side sealing area 13 arranged along the length direction (Y-axis direction) of the perforation 11;

[0056] The side sealing area 13 and / or the top sealing area 12 are sequentially configured along their thickness direction as a nylon layer 121, an aluminum foil layer 122, a hot melt adhesive layer 123, and a low melting point adhesive layer 124. The nylon layer 121 and the aluminum foil layer 122 are bonded together by an adhesive layer, and the aluminum foil layer 122 and the hot melt adhesive layer 123 are bonded together by an adhesive layer. The length of the low melting point adhesive layer 124 is less than or equal to the length of the side sealing area 13 and the top sealing area 12. The low melting point adhesive layer 124 is applied to the surface of the hot melt adhesive layer 123 in a segmented or continuous coating manner. The melting point of the hot melt adhesive layer 123 is 140℃-170℃, and the melting point of the low melting point adhesive layer 124 is 90℃-130℃.

[0057] The working principle of the above technical solution is as follows: under the high-temperature environment of the hot box test, the low-melting-point adhesive layer 124 first reaches its melting point and begins to melt, thereby making the sealing area of ​​the aluminum-plastic film 100 relatively less airtight. This design allows the gas and heat generated inside the battery to escape through the sealing area before the pressure becomes too high, effectively avoiding safety problems caused by excessive internal pressure. In addition, since the melting point of the low-melting-point adhesive layer 124 is much lower than that of the hot-melt adhesive layer 123, it will not affect the sealing performance of the battery within the normal operating temperature range. In this way, the aluminum-plastic film 100 of the present invention not only improves the thermal stability of the battery under high-temperature conditions, but also does not sacrifice the charging performance and capacity of the battery, thereby achieving dual protection of battery performance and safety.

[0058] Furthermore, the low-melting-point adhesive layer 124 of this application partially or completely covers the top sealing area 12 or the side sealing area 13, thereby forming a low-melting-point aluminum-plastic film 100. The low-melting-point adhesive layer 124, also known as a low-melting-point polymer adhesive layer, weakens the battery's encapsulation capability. Within the battery's normal operating temperature range of -20℃ to 60℃, the low-melting-point aluminum-plastic film 100 has no impact on the battery's encapsulation performance. However, during hot-box testing, the high temperature causes the low-melting-point adhesive layer 124 at the sealing point of the aluminum-plastic film 100 to reach a molten state, opening the film and releasing gas and heat, thus preventing hot-box failure; and improving battery safety performance without altering the battery's electrical performance or normal use.

[0059] like Figure 2 As shown, the number of low-melting-point adhesive layers 124 located in the top sealing area 12 or side sealing area 13 of the aluminum-plastic film 100 can be one or more. The specific implementation of the low-melting-point adhesive layer 124 is diverse, including solid hot-press bonding, molten coating, and solution coating. It is worth noting that the melting point of the low-melting-point adhesive layer 124 is between 90℃ and 130℃, while the melting point of the inner hot-melt adhesive layer 123 is between 140℃ and 170℃. The encapsulation temperature of the aluminum-plastic film 100 is generally higher than 170℃. At this encapsulation temperature, the hot-melt adhesive layer 123, the core tab 21 adhesive, and the low-melting-point adhesive layer 124 of the aluminum-plastic film 100 melt together, completing the encapsulation. Compared to conventional aluminum-plastic film 100, within the normal operating temperature range of -20℃ to 60℃, the sealing strength of low-melting-point aluminum-plastic film 100 is comparable to that of conventional aluminum-plastic film 100. During hot box testing at temperatures above 130℃, which is higher than the melting point of low-melting-point adhesive layer 124, the low-melting-point adhesive layer 124 in the sealing area melts, releasing gas and heat, increasing the heat dissipation rate, and reducing the risk of thermal runaway.

[0060] Specifically, the solid bonding method refers to pre-melting and blending low-melting-point adhesive and then using methods such as extrusion blow molding, extrusion casting, and solution casting to form a film roll with a certain thickness. The low-melting-point adhesive film is then cut into a certain length and width and hot-pressed onto a specific position of the aluminum-plastic film 100 to form the low-melting-point aluminum-plastic film 100.

[0061] In this application, the thickness of the hot melt adhesive layer 123 is C, and the thickness of the low-melting-point adhesive layer 124 is e, where C and e satisfy 0.2 ≤ C / e. The specific thickness of the low-melting-point adhesive layer 124 can be 5μm-50μm. In specific implementations, it can be: 5μm, 7μm, 10μm, 15μm, 20μm, 25μm, 30μm, 40μm, or 50μm. When the thickness of the low-melting-point adhesive layer 124 is less than the defined minimum thickness, the sealing effect of the sealing area is not significantly weakened, leading to thermal box failure. By selecting different thickness values, optimization can be performed for different application requirements to achieve the best sealing effect and performance. For example, a thinner low-melting-point adhesive layer 124 is suitable for applications requiring rapid heat dissipation, while a thicker adhesive layer may provide better sealing strength. In practical applications, other performance parameters of the aluminum-plastic film 100, such as tensile strength, air permeability, and chemical resistance, also need to be considered to ensure the balance and optimization of overall performance. However, when the thickness of the low-melting-point adhesive layer 124 is less than the minimum thickness of 5μm mentioned above, the sealing effect of the top sealing area 12 or the side sealing area 13 with the low-melting-point adhesive layer 124 will be weakened, resulting in the failure of the hot box.

[0062] As a further improvement to the aluminum-plastic film 100 of this application, the top sealing area 12 is provided with a first sealing area 125, and the side sealing area 13 is provided with a second sealing area 131; the width of both the top sealing area 12 and the side sealing area 13 is 'a', the width of both the first sealing area 125 and the second sealing area 131 is 'b', and the width of the low-melting-point adhesive layer 124 is 'B'; wherein a, b, and B satisfy b≤B≤a. It should be noted that the widths of the first sealing area 125 and the second sealing area 131 are determined by the width of the sealing head when the aluminum-plastic film 100 is sealed. Since a width greater than the widths of the first and second sealing areas 131 of this application would lead to a decrease in the sealing performance of the aluminum-plastic film 100, it is necessary to ensure that the width of the sealing head matches the width of the sealing area during design. Only when the widths of the first sealing area 125 and the second sealing area 131 are greater than the width of the sealing head can the heat-sealing width of the aluminum-plastic film 100 be guaranteed to meet the width of the sealing head. When B is too small, the area of ​​the low-melting-point adhesive layer 124 is too small, resulting in a weak and insignificant sealing effect in the sealing area, leading to thermal box failure. When B is large, the low-melting-point adhesive layer 124 penetrates into the battery body, affecting the battery size and causing a change in the battery's volumetric energy density. Only when B is within the range of b and a can the optimal balance between the sealing effect of the aluminum-plastic film 100 and the battery performance be ensured.

[0063] Furthermore, the low-melting-point adhesive layer 124 is prepared by blending a first polymer and a second polymer. The first polymer is a mixture of polyethylene and polypropylene, and the second polymer is a modified polymer used to modify the melting point of the low-melting-point adhesive layer 124. Therefore, the melting point of the low-melting-point adhesive layer 124 can be adjusted as needed to adapt to different battery designs and safety requirements. The mixing ratio of polyethylene and polypropylene, as well as the type and ratio of the modified polymer, can be optimized according to actual applications to achieve optimal thermal stability and sealing performance. For example, by adjusting the ratio of polyethylene and polypropylene, the melting point range of the low-melting-point adhesive layer 124 can be controlled, thereby ensuring battery safety at high temperatures while also ensuring the battery's sealing performance at normal operating temperatures.

[0064] Furthermore, the aluminum-plastic film 100 of the present invention also takes into account the mechanical strength and durability of the battery during actual use. By optimizing the thickness ratio of the hot melt adhesive layer 123 to the low melting point adhesive layer 124, the aluminum-plastic film 100 can ensure that it provides thermal stability while also possessing sufficient mechanical strength to resist external impacts and pressures. This design not only improves battery safety but also extends battery life.

[0065] Furthermore, polyethylene has a number-average molecular weight of 80,000-120,000 and a melting point of 85℃-125℃.

[0066] Polypropylene has a number-average molecular weight of 40,000-100,000 and a melting point of 100℃-160℃, which gives the low-melting-point adhesive layer 124 good melting properties at high temperatures while maintaining sufficient mechanical strength. In practical applications, this material combination ensures that the low-melting-point adhesive layer 124 can melt in time when the internal temperature of the battery rises, and can quickly solidify when the battery temperature returns to normal, ensuring that the battery's sealing performance is not affected.

[0067] Furthermore, the mass ratio of polyethylene to polypropylene in the low-melting-point adhesive layer 124 is 0-1:0-1. This design allows the physical and chemical properties of the low-melting-point adhesive layer 124 to be flexibly adjusted according to different application scenarios and safety requirements. For example, by changing the mass ratio of polyethylene to polypropylene, the melting point and mechanical strength of the adhesive layer can be adjusted to adapt to different battery designs and usage environments. This flexibility enables the aluminum-plastic film 100 to better meet the needs of different types of batteries in terms of thermal stability, mechanical strength, and safety performance.

[0068] Furthermore, the second polymer is composed of one or more of the following: maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, polymethyl methacrylate, acrylonitrile-butadiene-styrene, polylactic acid, polyvinyl chloride, polyvinyl butyral, polyacrylonitrile, or polyvinylidene fluoride. The introduction of these modified polymers can further improve the thermal and chemical stability of the low-melting-point adhesive layer 124, while enhancing its adhesion to other parts of the battery, ensuring the reliability of the battery under high temperatures and harsh environments.

[0069] Furthermore, the mass ratio of the first polymer to the second polymer is 1:0-0.2. This ratio design allows for the introduction of appropriate amounts of modified polymers to achieve specific performance optimizations while maintaining the basic properties of the low-melting-point adhesive layer 124. In this way, it can be ensured that the aluminum-plastic film 100 provides sufficient mechanical strength and durability while also offering thermal stability.

[0070] Figure 4 As shown in the top view of the battery prepared by packaging the battery cell 2 with the aluminum-plastic film 100 of this application, the battery provided in this application includes the aluminum-plastic film 100 as described above and the battery cell 2 disposed in two perforations 11 within the aluminum-plastic film 100; the battery cell 2 extends with tabs 21, which are bonded to the top sealing area 12 through an adhesive layer. Thus, the battery structural design ensures that, under high-temperature conditions, the gas and heat generated inside the battery can be effectively discharged through the low-melting-point adhesive layer 124 of the aluminum-plastic film 100, thereby avoiding safety problems caused by excessive internal pressure. It should be noted that this application... Figure 3 The battery shown was cut to remove, as... Figure 2 The air bag in the aluminum-plastic film 100 shown, at the same time Figure 2 The aluminum-plastic film 100 encapsulation process shown is to fold along the vertical line of the length direction (X-axis direction) of the aluminum-plastic film 100 so that the two punched pits 11 can be assembled with the battery cell 2 and the battery cell 2 is sealed in the punched pits 11 by the top sealing area 12 and the side sealing area 13.

[0071] Furthermore, the length of the low-melting-point adhesive layer 124 of the aluminum-plastic film 100 is A, the width of the battery is c, and the length of the battery is d. When the low-melting-point adhesive layer 124 is segmented, the length A of the low-melting-point adhesive layer 124 represents the length of each segment of the low-melting-point adhesive layer 124, and the number of segments of the low-melting-point adhesive layer 124 is n. When the low-melting-point adhesive layer 124 is continuously coated, the number of time segments is n=1. Among them, A, c, d, and n satisfy 0.02≤n*A / c or n*A / d≤1.

[0072] When n*A is too small, the low-melting-point adhesive layer 124 has a small area and a low breaking rate, which cannot meet the rapid breaking requirements of the hot box test, thus causing the function of relieving battery pressure during the hot box test to fail. When n*A is greater than the defined maximum length, it not only affects the battery size, but also causes excessive polymer layer to overflow adhesive. When the side edge is folded, the aluminum layer will crack, which may lead to leakage and hot box failure.

[0073] Furthermore, the battery prepared from the aluminum-plastic film of this application can be any one of lithium-ion batteries, sodium-ion batteries, zinc-ion batteries, solid-state batteries, vanadium batteries, zirconium batteries, etc. in the specific implementation process.

[0074] Specifically, the hot box test procedure for the battery prepared in this application is as follows: First, the battery is charged at 0.5C to the upper limit voltage (0.02C cutoff) to test the initial state of the battery, including voltage, internal resistance, thickness, etc.; then, the battery is placed in an oven and heated at an initial temperature of 25±3℃, with a heating rate of 5±2℃ to 130±2℃, and held for 60 minutes before the test ends. Judgment criteria: The battery does not catch fire or explode.

[0075] The present invention will be further described in detail below with reference to specific embodiments and the results of hot box tests in each embodiment, but the embodiments of the present invention are not limited thereto.

[0076] Example 1

[0077] The battery in this embodiment is a lithium-ion soft-pack battery, wherein the prepared battery has a thickness of 4.2 mm, a width of 65 mm, and a length of 82 mm; wherein the top sealing area 12 has a width of 2.4 mm, the side sealing area 13 has a width of 6 mm, and the widths of the first sealing area 125 and the second sealing area 131 are both 1.3 mm.

[0078] The aluminum-plastic film 100 has a thickness of 103 μm, the nylon layer 121 and the adhesive layer are both 28 μm thick, the aluminum foil layer 122 has a thickness of 40 μm, and the hot melt adhesive layer 123 has a thickness of 35 μm. The melting point of the hot melt adhesive layer 123 of the aluminum-plastic film 100 is 160℃. In this embodiment, a low-melting-point adhesive layer 124 is hot-pressed onto the surface of the hot melt adhesive layer 123 in the top sealing area 12 of the aluminum-plastic film 100 using a solid bonding method. The low-melting-point adhesive layer 124 has a length of 3.2 mm, a width of 1.5 mm, and a thickness of 10 μm. The low-melting-point adhesive layer 124 has a melting point of 96℃ and is thermally fused with the tab 21 adhesive of the bare core, the hot melt adhesive layer 123, and the tab 21 adhesive.

[0079] In this embodiment, the low-melting-point adhesive layer 124 is only attached to the top sealing area 12, and the number of strips is 1. The first polymer used to prepare the low-melting-point adhesive layer 124 in this embodiment is polyethylene; the second polymer is polymethyl methacrylate; the mass ratio of the first polymer to the second polymer is 1:0.1.

[0080] Example 2

[0081] Unlike Example 1, in this example, the mass ratio of the first polymer to the second polymer is 1:0.2; and the melting point of the low-melting-point adhesive layer 124 is 100°C.

[0082] Example 3

[0083] Unlike Example 1, the first polymer in this example is a mixture of polyethylene and polypropylene; wherein the mass ratio of polyethylene to polypropylene is 1:0.5.

[0084] The melting point of the low-melting-point adhesive layer 124 is 105℃.

[0085] Example 4

[0086] Unlike Example 1, the first polymer in this example is a mixture of polyethylene and polypropylene; wherein the mass ratio of polyethylene to polypropylene is 1:1.

[0087] The melting point of the low-melting-point adhesive layer 124 is 110℃.

[0088] Example 5

[0089] Unlike Example 1, the first polymer in this example is a mixture of polyethylene and polypropylene; wherein the mass ratio of polyethylene to polypropylene is 1:1.

[0090] The second polymer is a mixture of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, polymethyl methacrylate, acrylonitrile-butadiene-styrene, polylactic acid, polyvinyl chloride, polyvinyl butyral, polyacrylonitrile, or polyvinylidene fluoride.

[0091] The melting point of the low-melting-point adhesive layer 124 is 114℃.

[0092] Example 6

[0093] Unlike Example 1, the first polymer in this example is polypropylene; the second polymer is polymethyl methacrylate.

[0094] The melting point of the low-melting-point adhesive layer 124 is 123℃.

[0095] Example 7

[0096] Unlike Example 1, in this example, the first polymer is polypropylene; the second polymer is polymethyl methacrylate; and the mass ratio of the first polymer to the second polymer is 1:0.2.

[0097] The melting point of the low-melting-point adhesive layer 124 is 130℃.

[0098] Comparative Example 1

[0099] Unlike Example 1, this comparative example does not have a low-melting-point adhesive layer 124.

[0100] Comparative Example 2

[0101] Unlike Example 1, in this comparative example, the first polymer of the low-melting-point adhesive layer 124 is polypropylene, and there is no second polymer.

[0102] Comparative Example 3

[0103] Unlike Example 1, in this comparative example, the low-melting-point adhesive layer 124 has no first polymer, which is polypropylene, and the second polymer is polymethyl methacrylate.

[0104] The results of the hot box tests conducted on Examples 1-7 and Comparative Example 1 are shown in Table 1 below.

[0105]

[0106] Table 1

[0107] As shown in Table 1, the aluminum-plastic film 100 of the present invention exhibited excellent performance in the hot box test. In Examples 1 to 7, all batteries passed the hot box test, and the peak temperatures of the batteries were all within an acceptable range. This indicates that by rationally designing the melting point, thickness, width, and coating method of the low-melting-point adhesive layer 124, the safety performance of the battery in a high-temperature environment can be effectively controlled. In particular, the peak temperatures of the batteries in Examples 1 to 7 in the hot box test were all below 135°C, meeting the safety requirements of the battery in a high-temperature environment.

[0108] Further analysis showed that the batteries in Examples 1 to 7 all achieved a 100% pass rate in the hot box test, indicating that the introduction of the low-melting-point adhesive layer 124 significantly improved battery safety performance, especially under high-temperature conditions. In Comparative Example 1, due to the lack of the low-melting-point adhesive layer 124, all batteries failed the hot box test; in Comparative Example 2, only half passed (5 out of 10); and in Comparative Example 3, only one more battery passed than in Comparative Example 2. This further demonstrates the importance of the low-melting-point adhesive layer 124 in the battery safety performance of this application.

[0109] Regarding the size and position parameters, the batteries in Examples 1 to 7 all meet the condition of n*A / c or n*A / d. This indicates that the length and number of segments of the low-melting-point adhesive layer 124 are in appropriate proportion to the size of the battery. This ensures that there is enough area of ​​the low-melting-point adhesive layer 124 to meet the rapid breaking requirements in the hot box test, while avoiding problems such as adhesive overflow and aluminum layer cracking that may be caused by the low-melting-point adhesive layer 124 being too long or having too many segments.

[0110] Furthermore, Examples 2-7, Comparative Examples 2 and 3 modified the material composition of the low-melting-point adhesive layer 124 based on Example 1. The hot-box results from the examples and comparative examples show that, with the change in material composition, the low-melting-point adhesive layer 124 can pass through hot boxes within the defined melting point range of 90-130°C. However, the melting point of the first polymer or the pure second polymer is too high, failing to weaken the encapsulation effect and causing hot box failure.

[0111] Furthermore, embodiments 1-7 of this application further optimize the thermal stability of the battery by adjusting the melting point of the low-melting-point adhesive layer 124. By comparing the melting points of the low-melting-point adhesive layer 124 in embodiments 1-7, it can be seen that as the melting point increases, the peak temperature of the battery in the hot box test also increases accordingly. This indicates that by selecting a suitable melting point, the thermal stability of the battery can be finely controlled for different application scenarios and safety requirements. For example, for batteries that need to operate in higher temperature environments, the melting point of the low-melting-point adhesive layer 124 can be appropriately increased to ensure the battery's safety performance under extreme conditions. At the same time, the selection of the melting point also needs to consider the battery's sealing performance at normal operating temperatures to avoid affecting the normal use of the battery due to an excessively high melting point.

[0112] In summary, the aluminum-plastic film 100 of the present invention significantly improves the safety performance of the battery in high-temperature environments by optimizing the physical and chemical properties of the low-melting-point adhesive layer 124, providing a new solution for the safe use of batteries.

[0113] Example 8

[0114] Unlike Example 1, in this example, the low melting point adhesive layer 124 is coated onto the surface of the hot melt adhesive by melt coating.

[0115] Example 9

[0116] Unlike Example 1, in this example, the low melting point adhesive layer 124 is coated onto the surface of the hot melt adhesive by solution coating.

[0117] The results of the hot box tests conducted on Examples 1 and 8-9 above are shown in Table 2 below.

[0118]

[0119] Table 2

[0120] As shown in Table 2, the batteries of Examples 8 and 9 also exhibited good performance in the hot box test, with a pass rate of 100% and peak temperatures within an acceptable range. This indicates that, regardless of whether the coating method is melt coating or solution coating, the low-melting-point adhesive layer 124 can effectively bond with the hot-melt adhesive layer 123, ensuring the battery's safety performance in high-temperature environments. In particular, Example 9, which uses solution coating, showed only a slight increase in peak temperature compared to Examples 1 and 8, indicating that different coating methods have limited impact on battery performance, but all meet the battery safety requirements. Furthermore, the dimensional position parameters of Examples 8 and 9 both satisfy the condition n*A / c or n*A / d, further demonstrating the adaptability of the low-melting-point adhesive layer 124 coating method to battery size and safety performance. In summary, the aluminum-plastic film 100 of the present invention provides a flexible and safe encapsulation solution for batteries through different coating methods, ensuring the stability and reliability of batteries in various environments.

[0121] Example 10

[0122] Unlike Example 1, in this example, the low melting point adhesive layer 124 is disposed in the bottom sealing area, which is disposed corresponding to the top sealing area 12 along the length direction (X-axis direction) of the battery.

[0123] Example 11

[0124] Unlike Example 1, in this example, the low melting point adhesive layer 124 is disposed in the side sealing area 13 without an air bag.

[0125] Example 12

[0126] Unlike Example 1, in this example, the low melting point adhesive layer 124 is disposed in the side sealing area 13 with the air bag.

[0127] Example 13

[0128] Unlike Example 1, in this example, the low melting point adhesive layer 124 is provided in both the top sealing area 12 and the bottom sealing area; the number n of the low melting point adhesive layer 124 is 2.

[0129] Example 14

[0130] Unlike Example 1, in this example, the low-melting-point adhesive layer 124 is provided in both the side sealing area 13 with and without the air bag; the number n of the low-melting-point adhesive layer 124 is 2.

[0131] Example 15

[0132] Unlike Example 1, in this example, the low melting point adhesive layer 124 is provided in both the bottom sealing area and the side sealing area 13 without air bag; the number n of the low melting point adhesive layer 124 is 2.

[0133] Example 16

[0134] Unlike Example 1, in this example, the length of the low melting point adhesive layer 124 is 0.65 mm.

[0135] Example 17

[0136] Unlike Example 1, in this example, the length of the low melting point adhesive layer 124 is 0.8 mm, and it is disposed in the side sealing area 13 without an air bag.

[0137] Example 18

[0138] Unlike Example 1, in this example, the length of the low-melting-point adhesive layer 124 is 1 mm.

[0139] Comparative Example 4

[0140] Unlike Example 1, in this comparative example, the low melting point adhesive layer 124 is disposed in the non-sealing area.

[0141] The results of the hot box tests conducted on Examples 1 and 10-18 are shown in Table 3 below.

[0142]

[0143] Table 3

[0144] As shown in Table 3, the pass rate of the batteries in Examples 16 to 18 decreased in the hot box test, which may be related to the length of the low-melting-point adhesive layer 124. When the length of the low-melting-point adhesive layer 124 is too short, it may not provide sufficient sealing area to meet the rapid rupture requirements in the hot box test, resulting in reduced battery safety under high-temperature conditions. In particular, in Example 18, the length of the low-melting-point adhesive layer 124 was 1 mm, and its pass rate was only 70%, with a peak temperature of 160°C. This indicates that the length of the low-melting-point adhesive layer 124 being too short may not meet the safety requirements of the battery under high-temperature conditions. Although the pass rate of the batteries in Examples 16 and 17 was 100%, the peak temperatures reached 140°C and 154°C, respectively, indicating that the length of the low-melting-point adhesive layer 124 has a certain impact on the thermal stability of the battery. Comparative Example 4 did not apply the low-melting-point adhesive layer 124 to any sealing area, so it did not produce any technical effect.

[0145] Therefore, when designing the low-melting-point adhesive layer 124, its length, melting point, and coating method need to be comprehensively considered to ensure the battery's safety performance in various environments. Through proper design, the battery's safety and reliability in high-temperature environments can be ensured, meeting the needs of different application scenarios.

[0146] Example 19

[0147] Unlike Example 1, in this example, the number of low-melting-point adhesive layers 124 coated is n=15.

[0148] Example 20

[0149] Unlike Example 1, in this example, the number of low-melting-point adhesive layers 124 coated is n=20.

[0150] Example 21

[0151] Unlike Example 1, in this example, the number of low-melting-point adhesive layers 124 applied is n=25; the low-melting-point adhesive layers 124 are disposed in the airless bag side sealing area 13.

[0152] Example 22

[0153] Unlike Example 1, in this example, the length of the low-melting-point adhesive layer 124 is 65 mm.

[0154] Example 23

[0155] Unlike Example 1, in this example, the length of the low-melting-point adhesive layer 124 is 82 mm; the low-melting-point adhesive layer 124 is disposed in the airless bag side sealing area 13.

[0156] Example 24

[0157] Unlike Example 1, in this example, the thickness of the low-melting-point adhesive layer 124 is 1 mm.

[0158] The results of the hot box tests conducted on Examples 1 and 19-25 are shown in Table 4 below.

[0159]

[0160] Table 4

[0161] As shown in Table 4, the batteries of Examples 19 to 23 exhibited different performance in the hot box test. The batteries of Examples 19 and 20 both had a 100% pass rate, but the peak temperature increased slightly with the increase in the amount of low-melting-point adhesive layer 124 applied. This indicates that increasing the amount of low-melting-point adhesive layer 124 can improve the thermal stability of the battery to some extent, but it also leads to an increase in the peak temperature. The battery of Example 21 also had a 100% pass rate, but the peak temperature further increased to 136°C. This may be related to the fact that the low-melting-point adhesive layer 124 was located in the airless side-sealing area 13, which may require more low-melting-point adhesive layer 124 to ensure a good seal.

[0162] The battery pass rates for Examples 22 and 23 were 90% and 100%, respectively, with peak temperatures of 141°C and 130°C, indicating that the length of the low-melting-point adhesive layer 124 has a significant impact on the battery's thermal stability. Specifically, when the length of the low-melting-point adhesive layer 124 is too long, it may cause a decrease in battery performance during the hot-box test. Furthermore, when 0.02 ≤ n*A / c or n*A / d ≤ 1, the hot-box test can be passed. When n*A / c or n*A / d < 0.02, the low-melting-point adhesive layer 124 does not significantly weaken the encapsulation, and the hot-box test may fail. When n*A / c or n*A / d > 1, excessive polymer material causes adhesive overflow during the heat sealing of the cell 2, leading to cracking of the aluminum foil layer 122 and a probability of hot-box failure.

[0163] The battery in Example 24 had a yield of 80% and a peak temperature of 163°C, indicating that increasing the thickness of the low-melting-point adhesive layer 124 does not necessarily lead to better thermal stability; on the contrary, it may affect the normal operating temperature of the battery. Therefore, when designing the low-melting-point adhesive layer 124, it is necessary to balance the coating quantity, length, and thickness to achieve optimal battery safety performance.

[0164] Example 25

[0165] Unlike Example 1, the width of the low melting point adhesive layer 124 in this example is 2 mm.

[0166] Example 26

[0167] Unlike Example 1, the thickness of the low-melting-point adhesive layer 124 in this example is 5 μm.

[0168] Example 27

[0169] Unlike Example 1, in this example, the thickness of the low-melting-point adhesive layer 124 is 5 μm and the length is 41 mm; the low-melting-point adhesive layer 124 is disposed in the side sealing area 13 without an air bag.

[0170] Example 28

[0171] Unlike Example 1, in this example, the thickness of the low-melting-point adhesive layer 124 is 7 μm; the low-melting-point adhesive layer 124 is disposed in the side sealing area 13 without an air bag.

[0172] Example 29

[0173] Unlike Example 1, the thickness of the low-melting-point adhesive layer 124 in this example is 20 μm.

[0174] Example 30

[0175] Unlike Example 1, the thickness of the low-melting-point adhesive layer 124 in this example is 30 μm.

[0176] Example 31

[0177] Unlike Example 1, the thickness of the low-melting-point adhesive layer 124 in this example is 50 μm.

[0178] The results of the hot box tests conducted on Examples 1 and 26-31 are shown in Table 5 below.

[0179]

[0180] Table 5

[0181] like Figure 4 The data shows that the batteries of Examples 25 to 31 exhibited different performance in the hot box test. The battery of Example 25 maintained a 100% yield, with a slight increase in peak temperature to 131°C, indicating that appropriately increasing the width of the low-melting-point adhesive layer 124 can provide better sealing without significantly affecting the battery's thermal stability. The changes in yield and peak temperature of the batteries of Examples 26 to 31 demonstrate the impact of the thickness of the low-melting-point adhesive layer 124 on battery performance.

[0182] In Examples 26 and 27, the battery yield decreased slightly to 90%, while the peak temperatures reached 148°C and 145°C, respectively. This may be related to the reduced thermal conductivity caused by the excessive thickness of the low-melting-point adhesive layer 124. In Examples 28 to 31, the battery yield was 100%, but the peak temperature increased with increasing thickness. This indicates that increasing the thickness of the low-melting-point adhesive layer 124 within a certain range can improve the thermal stability of the battery, but an excessively thick adhesive layer may lead to a decrease in battery performance at high temperatures.

[0183] Furthermore, Examples 24 and 25 modify the width B of the low-melting-point adhesive layer 124 compared to Example 1. When B ≥ b, the hot box can pass through. When the width B of the low-melting-point adhesive layer 124 < b, the sealing weakening effect is not obvious, and the hot box has a probability of failure.

[0184] Examples 26-31 modify the thickness C of the low-melting-point adhesive layer 124 based on Example 1. When C is within the thickness defined in the patent, i.e., C / e≥0.2, the hot box can pass through. When C / e<0.2, the low-melting-point adhesive layer 124 is too thin, the sealing effect is not obvious, and the hot box has a probability of failure.

[0185] Therefore, when designing the low-melting-point adhesive layer 124, its width, length, and thickness need to be comprehensively considered to ensure the battery's safety performance and thermal stability under various environments. Through proper design, the battery's safety and reliability in high-temperature environments can be ensured, meeting the needs of different application scenarios.

[0186] As shown in Tables 1-5, the low-melting-point adhesive layer 124 can significantly improve the hot box throughput.

[0187] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery, characterized in that, Includes an aluminum-plastic film and a battery cell (2) disposed in two perforations (11) of the aluminum-plastic film. The aluminum-plastic film includes two symmetrically arranged perforations (11), a top sealing area (12) arranged on one side along the width direction of the perforations (11), and a side sealing area (13) arranged along the length direction of the perforations (11). The side sealing area (13) and / or the top sealing area (12) are sequentially configured along their thickness direction as a nylon layer (121), an aluminum foil layer (122), a hot melt adhesive layer (123), and a low melting point adhesive layer (124). The nylon layer (121) and the aluminum foil layer (122) are bonded together by an adhesive layer, and the aluminum foil layer (122) and the hot melt adhesive layer (123) are bonded together by an adhesive layer. The length of the low melting point adhesive layer (124) is less than or equal to the length of the side sealing area (13) and the top sealing area (12). Meanwhile, the low melting point adhesive layer (124) is coated on the surface of the hot melt adhesive layer (123) in a segmented coating or continuous coating manner. The melting point of the hot melt adhesive layer (123) is 140℃-170℃, and the melting point of the low melting point adhesive layer (124) is 90℃-130℃. The thickness of the hot melt adhesive layer (123) is C, and the thickness of the low melting point adhesive layer (124) is e, wherein C and e satisfy 0.2≤C / e; The battery cell (2) is provided with tabs (21), which are bonded to the top sealing area (12) through tab adhesive layer (211).

2. The battery according to claim 1, characterized in that, The low-melting-point adhesive layer (124) is prepared by blending a first polymer and a second polymer. The first polymer is a mixture of polyethylene and polypropylene, and the second polymer is a modified polymer used to modify the melting point of the low-melting-point adhesive layer (124).

3. A battery according to claim 2, characterized in that, The polyethylene has a number average molecular weight of 80,000-120,000 and a melting point of 85℃-125℃. The polypropylene has a number average molecular weight of 40,000-100,000 and a melting point of 100℃-160℃.

4. A battery according to claim 2, characterized in that, The mass ratio of polyethylene to polypropylene in the low-melting-point adhesive layer (124) is (0-1):(0-1).

5. A battery according to claim 2, characterized in that, The second polymer is composed of one or more of the following: maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, polymethyl methacrylate, acrylonitrile-butadiene-styrene, polylactic acid, polyvinyl chloride, polyvinyl butyral, polyacrylonitrile, or polyvinylidene fluoride.

6. A battery according to claim 2, characterized in that, The mass ratio of the first polymer to the second polymer is 1:(0-0.2).

7. A battery according to claim 1, characterized in that, The top sealing area (12) is provided with a first sealing area (125), and the side sealing area (13) is provided with a second sealing area (131); the width of the top sealing area (12) and the side sealing area (13) is a, the width of the first sealing area (125) and the width of the second sealing area (131) are b, and the width of the low melting point adhesive layer (124) is B; Among them, a, b and B satisfy b≤B≤a.

8. A battery according to claim 1, characterized in that, The length of the low-melting-point adhesive layer (124) of the aluminum-plastic film is A, the width of the battery is c, and the length of the battery is d. When the low-melting-point adhesive layer (124) is segmented, the length A of the low-melting-point adhesive layer (124) represents the length of each segment of the low-melting-point adhesive layer (124), and the number of segments of the low-melting-point adhesive layer (124) is n. When the low-melting-point adhesive layer (124) is continuously coated, the number of segments n=1. Among them, A, c, d, and n satisfy 0.02≤n*A / c or n*A / d≤1.

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