Aluminum plastic film and battery

Abstract

The invention belongs to the technical field of batteries, and mainly relates to an aluminum-plastic film which comprises two symmetrically-arranged punching pits, a top sealing area arranged on one side in the width direction of the punching pits and a side sealing area arranged in the length direction of the punching pits. A nylon layer, an aluminum foil layer, a hot melt adhesive layer and a low-melting-point adhesive layer are sequentially arranged in the side sealing area and / or the top sealing area in the thickness direction of the side sealing area and / or the top sealing area, the nylon layer and the aluminum foil layer are bonded through a bonding layer, and the aluminum foil layer and the hot melt adhesive layer are bonded through a bonding layer. The length of the low-melting-point adhesive layer is smaller than or equal to the length of the side sealing area and the length of the top sealing area, and meanwhile, the surface of the hot melt adhesive layer is coated with the low-melting-point adhesive layer in a segmented coating or continuous coating mode; the melting point of the hot melt adhesive layer is 140-170 DEG C, and the melting point of the low-melting-point adhesive layer is 90-130 DEG C; therefore, the battery prepared from the aluminum-plastic film can maintain the thermal stability and the battery performance at the same time; meanwhile, the battery is prepared, and the performance of the battery is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and particularly relates to an aluminum-plastic film and a battery. Background Art

[0002] Since the commercial application of batteries, they have been widely used in consumer electronics, electric vehicles, and energy storage fields due to their high energy density, high power density, excellent cycling performance, low self-discharge rate, and environmental friendliness. However, with the rapid development of technology, battery products are gradually evolving towards high charging rate fast charging and high voltage. Although the upgrade of these technologies has improved the performance of batteries, it has also significantly increased the risk of thermal stability of batteries in high-temperature environments.

[0003] The hot box test is one of the important means to evaluate the thermal stability of batteries. According to the requirements of the national standard GB31241, the battery needs to pass the hot box test at 130°C for 30 minutes to verify its safety and reliability in high-temperature environments. Under this test condition, if the battery fails to seal or has too high internal pressure due to high temperature, it may cause safety problems such as fire and explosion. Therefore, the main function of the hot box test is to simulate the performance of the battery under extreme temperature conditions, verify the safety of the battery, and ensure that it can meet the safety requirements in actual applications.

[0004] The existing technology mainly improves the stability of the battery in high-temperature environments by changing the battery material system, including the positive electrode material, negative electrode material, separator, electrolyte, and aluminum-plastic film, etc., to reduce the gas generation inside the battery at high temperatures. Although this adjustment of the material system can significantly improve the hot box performance of the battery, it often has an adverse impact on the charging performance or capacity of the battery. For example, when improving the thermal stability of the positive or negative electrode material, the energy density of the battery may be sacrificed; adjusting the thermal stability of the separator may affect the lithium-ion transmission efficiency, thereby reducing the charging rate or capacity of the battery. Therefore, there is a technical defect that it is difficult to balance between improving the hot box performance and maintaining the battery performance in the existing technical means.

[0005] Based on this, it is urgent to improve the existing aluminum-plastic film and battery to solve the above technical defects. Summary of the Invention

[0006] One of the purposes of the present invention is to provide an aluminum-plastic film that can maintain the battery performance while maintaining the thermal stability in view of the deficiencies of the existing technology.

[0007] In order to achieve the above technical purpose, the following technical solutions are implemented in this application:

[0008] An aluminum-plastic film includes two symmetrically arranged punching pits, a top-sealing area arranged on one side along the width direction of the punching pit, and a side-sealing area arranged along the length direction of the punching pit;

[0009] The side sealing area and / or the top sealing area are sequentially provided with a nylon layer, an aluminum foil layer, a hot melt adhesive layer and a low melting point adhesive layer along the thickness direction thereof; the nylon layer and the aluminum foil layer are bonded by an adhesive layer, and the aluminum foil layer and the hot melt adhesive layer are bonded 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, and at the same time, the low melting point adhesive layer is coated on the surface of the hot melt adhesive layer in the form of segmented coating or continuous coating;

[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 packaging structure, in which a low-melting-point glue layer is coated or pasted on the aluminum-plastic film seal. In a high-temperature environment, the low-melting-point glue layer melts within its melting point range, resulting in reduced sealing of the aluminum-plastic film seal. When a large amount of gas and heat are generated inside the battery due to high temperature, these gases and heat can be quickly discharged through the molten sealing area, thereby effectively alleviating the pressure accumulation inside the battery and avoiding safety issues such as fire or explosion caused by excessive internal pressure.

[0013] Compared with the prior art, the technical solution of this application does not involve any changes to the positive electrode, negative electrode, diaphragm, electrolyte, etc. of the battery material system, so it has no effect on the charging ability and capacity of the battery. At the same time, by adding a low-melting-point polymer glue layer in the aluminum-plastic film sealing area, rapid pressure relief under high temperature conditions can be achieved, significantly improving the hot box performance of the battery. This method not only improves the thermal stability of the battery, but also takes into account its high performance requirements, solving the technical defects of the prior art that affect battery performance when improving hot box performance.

[0014] As a further improvement to the aluminum-plastic film of the present 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 the present application, the number average molecular weight of the polyethylene is 80,000-120,000, and the melting point is 85° C.-125° C.;

[0016] The number average molecular weight of polypropylene is 40,000-100,000, and the melting point is 100°C-160°C.

[0017] As a further improvement to the aluminum-plastic film of the present 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 an aluminum-plastic film of the present 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 an aluminum-plastic film of the present application, the mass ratio of the first polymer to the second polymer is 1:0 - 0.2.

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

[0021] As a further improvement to an aluminum-plastic film of the present application, a first sealing area is provided in the top sealing area, and a second sealing area is provided in the side sealing area; the widths of both the top sealing area and the side sealing area are a, the widths of both the first sealing area and the second sealing area are 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 object of the present invention is to provide a battery that can maintain thermal stability while maintaining battery performance in view of the deficiencies of the prior art.

[0024] In order to achieve the above technical objectives, the following technical solutions are implemented in the present application:

[0025] A battery includes the aluminum-plastic film as described above in any one of the preceding items and an electric core disposed in two punching pits of the aluminum-plastic film; the electric core extends with a tab, and the tab is bonded to the top sealing area through a tab adhesive layer.

[0026] The above technical solutions have the following technical effects:

[0027] By adopting the aluminum-plastic film of the present invention, the battery has better thermal stability in a high-temperature environment, while maintaining the charging performance and capacity of the battery. Due to the presence of the low melting point adhesive layer 124, the battery can effectively release the internal pressure under high-temperature conditions, avoiding safety problems caused by excessive pressure.

[0028] As a further improvement to a battery of the present application, the length of the low melting point adhesive layer of the aluminum-plastic film is A, the width of the battery is c, the length of the battery is d. When the low melting point adhesive layer is coated in segments, 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 segments n = 1;

[0029] Among them, A, c, d, n satisfy 0.02 ≤ n*A / c or n*A / d ≤ 1. Description of the Drawings

[0030] The accompanying drawings described herein are used to provide a further understanding of the present invention and form a part of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

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

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

[0033] Figure 3 is Figure 2 a partial enlarged view at A;

[0034] Figure 4 is a schematic structural view of the battery of the present invention;

[0035] Wherein:

[0036] 100 - aluminum-plastic film;

[0037] 11 - pit;

[0038] 12 - top seal 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 sealing area

[0044] 13 - side seal area;

[0045] 131 - second sealing area;

[0046] 2 - battery cell

[0047] 21 - tab;

[0048] 211 - tab adhesive. Detailed implementation manners

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the scope of protection of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs. The terms used in the description of the present application in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0050] In the description of the present invention, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected", and "fixed" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0051] Although the present application is disclosed above with preferred embodiments, it is not used to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of the present application. Therefore, the scope of protection of the present application should be determined by the scope defined by the claims of the present application.

[0052] In the prior art, it is known that the principle of hot box testing is to place the battery in a high-temperature environment to simulate the battery performance under extreme temperature conditions. If the battery experiences seal failure or excessive internal pressure at high temperature, it may cause safety problems. Therefore, hot box testing is one of the important means to evaluate the thermal stability of the battery. However, while improving the thermal stability of the battery, the prior art often has an adverse impact on the charging performance or capacity of the battery.

[0053] Specifically, in the hot box test process, the battery is fully charged and then placed in a temperature-controlled box. The temperature of the box is raised to a specific temperature and maintained for a certain period of time, and then it is observed whether the battery catches fire. The national standard GB31241 stipulates that the battery needs to pass the hot box test at 130°C for 30 minutes. For the traditional battery aluminum plastic film 100, the melting temperature of the hot melt adhesive layer 123 is generally between 140°C and 170°C, which may not be melted in time in a high-temperature environment, resulting in the ineffective release of the internal pressure of the battery. Considering the technical defects in the hot box test process of the existing technology, if a sealing layer with a temperature lower than 130°C is provided during the sealing process of the aluminum plastic film 100, the size of the sealing layer can be smaller than the top sealing area 12 or the side sealing area 13, so that during the hot box test, a certain opening can be opened to enable the gas and heat generated inside the battery to quickly escape through the melted sealing area, effectively alleviating the pressure accumulation inside the battery and avoiding the impact on the battery caused by excessive internal pressure.

[0054] As Figures 1-4 shown, to solve the technical defect that the internal pressure of the battery is too high due to the tightness of the battery aluminum plastic film 100 in the hot box test process of the existing technology. This application provides an aluminum plastic film 100, which includes two symmetrically arranged punching pits 11, a top sealing area 12 arranged on one side along the width direction (X-axis direction) of the punching pit 11, and a side sealing area 13 arranged along the length direction (Y-axis direction) of the punching pit 11;

[0055] The side sealing area 13 and / or the top sealing area 12 are sequentially arranged as a nylon layer 121, an aluminum foil layer 122, a hot melt adhesive layer 123, and a low melting point adhesive layer 124 along the thickness direction. The nylon layer 121 and the aluminum foil layer 122 are bonded through an adhesive layer, and the aluminum foil layer 122 and the hot melt adhesive layer 123 are bonded through an adhesive layer; the length of the low melting point adhesive layer 124 is less than or equal to the lengths of the side sealing area 13 and the top sealing area 12. At the same time, 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 form; the melting point of the hot melt adhesive layer 123 is 140°C - 170°C, and the melting point of the low melting point adhesive layer 124 is 90°C - 130°C.

[0056] The working principle of the above technical solution is that in the high-temperature environment detected by the hot box, 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, the sealing performance of the battery will not be affected within the normal operating temperature range of the battery. In this way, the aluminum-plastic film 100 of the present invention not only improves the thermal stability of the battery in a high-temperature environment, but also does not sacrifice the charging performance and capacity of the battery, thus achieving a dual guarantee of battery performance and safety.

[0057] In addition, the low-melting-point adhesive layer 124 of the present application covers part or all of the top-sealing area 12 or the side-sealing area 13, thereby forming the low-melting-point aluminum-plastic film 100. The low-melting-point adhesive layer 124, also known as the low-melting-point polymer adhesive layer, weakens the encapsulation ability of the battery. Within the normal operating temperature range of the battery, -20°C to 60°C, the low-melting-point aluminum-plastic film 100 has no impact on the encapsulation performance of the battery. However, in the hot box test, at high temperatures, the low-melting-point adhesive layer 124 of the aluminum-plastic film 100 at the sealing part reaches the molten state, and the aluminum-plastic film 100 opens to release gas and heat, thus avoiding the failure of the hot box; without changing the electrical performance and normal use of the battery, the safety performance of the battery is improved.

[0058] As Figure 2 shown, the number of the low-melting-point adhesive layers 124 located in the top-sealing area 12 or the side-sealing area 13 of the aluminum-plastic film 100 can be one or more. The specific implementation methods of the low-melting-point adhesive layer 124 are diverse and can be solid-state hot-pressing paste, molten-state coating, and solution coating. It should be noted that the melting point of the low-melting-point adhesive layer 124 is between 90°C and 130°C, and the melting point of the inner-sealing hot-melt adhesive layer 123 is between 140°C and 170°C. The encapsulation temperature of the aluminum-plastic film 100 is generally higher than 170°C. At the encapsulation temperature, the hot-melt adhesive layer 123 of the aluminum-plastic film 100, the glue of the core ear 21, and the low-melting-point adhesive layer 124 melt with each other to complete the encapsulation. Compared with the conventional aluminum-plastic film 100, within the normal operating temperature range of the battery, -20°C to 60°C, the sealing strength of the low-melting-point aluminum-plastic film 100 is equivalent to that of the conventional aluminum-plastic film 100. During the hot box test, when the temperature is >130°C, the hot box test temperature is higher than the melting point of the low-melting-point adhesive layer 124, and the low-melting-point adhesive layer 124 in the sealing area melts open to release gas and heat, increasing the heat dissipation rate and reducing the risk of thermal runaway.

[0059] Specifically, the solid-state pasting method means pre-melting and co-blending the low-melting-point glue for hot processing, using methods such as extrusion blow molding, extrusion casting, and solution casting to form a thin film coil with a certain thickness, and then cutting the low-melting-point glue film into a certain length and width and hot-pressing and pasting it at a specific position on the aluminum-plastic film 100 to form the low-melting-point aluminum-plastic film 100.

[0060] Among them, the thickness value of the hot melt adhesive layer 123 in this application is C, and the thickness of the low melting point adhesive layer 124 is e, where C and e satisfy 0.2 ≤ C / e. Among them, the specific value of the thickness of the low melting point adhesive layer 124 can be 5 μm - 50 μm. In the specific implementation process, it can be: 5 μm, 7 μm, 10 μm. When the thickness of the low melting point adhesive layer 124 is less than the defined minimum thickness, the encapsulation effect of the sealing area is weakened insignificantly, resulting in the failure of the heat box. 15 μm, 20 μm, 25 μm, 30 μm, 40 μm or 50 μm. By selecting different thickness values, it can be optimized for different application requirements to achieve the best encapsulation effect and performance. For example, a thinner low melting point adhesive layer 124 is suitable for application scenarios that require 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, chemical resistance, etc., also need to be considered to ensure the balance and optimization of the overall performance. However, when the thickness of the low melting point adhesive layer 124 is less than the above-mentioned minimum thickness of 5 μm, the encapsulation effect of the top sealing area 12 or the side sealing area 13 provided with the above-mentioned low melting point adhesive layer 124 will be weakened, resulting in the failure of the heat box.

[0061] As a further improvement to an aluminum-plastic film 100 of this application, a first sealing area 125 is provided in the top sealing area 12, and a second sealing area 122 is provided in the side sealing area 13; the widths of the top sealing area 12 and the side sealing area 13 are both a, the widths of the first sealing area 125 and the second sealing area 122 are both b, and the width of the low melting point adhesive layer 124 is B; among them, a, b and B satisfy b ≤ B ≤ a. It should be noted here that the first sealing area 125 and the second sealing area 122 here are determined by the width of the sealing head when the aluminum-plastic film 100 is sealed. Since the sealing performance of the aluminum-plastic film 100 will decrease if the width of the sealing head is greater than the widths of the first sealing and the second sealing area 122 of this application, 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 122 are greater than the width of the sealing head can it be ensured that the heat sealing width of the aluminum-plastic film 100 meets the width of the sealing head. When B is too small, the area of the low melting point adhesive layer 124 is too small, and the encapsulation effect of the sealing area is weakened insignificantly, resulting in the failure of the heat box. When B is larger, the low melting point adhesive layer 124 penetrates into the battery body, affecting the battery size and resulting in a change in the volume energy density of the battery. Only when B satisfies the range between b and a can it be ensured that the encapsulation effect of the aluminum-plastic film 100 and the performance of the battery reach the best balance.

[0062] 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. Thus, 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 the actual application to achieve the best thermal stability and sealing effect. 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 the safety of the battery at high temperatures while also ensuring the sealing performance of the battery at normal operating temperatures.

[0063] In addition, 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 and the low melting point adhesive layer 124, it can be ensured that the aluminum-plastic film 100 not only provides thermal stability but also has sufficient mechanical strength to resist external impacts and pressures. This design not only improves the safety of the battery but also extends the service life of the battery.

[0064] Furthermore, the number average molecular weight of polyethylene is 80,000 - 120,000, and the melting point is 85°C - 125°C. The number average molecular weight of polypropylene is 40,000 - 100,000, and the melting point is 100°C - 160°C, enabling the low melting point adhesive layer 124 to have good melting properties at high temperatures while maintaining sufficient mechanical strength. In actual applications, this material combination can ensure that when the internal temperature of the battery rises, the low melting point adhesive layer 124 can melt in a timely manner, and when the battery temperature returns to normal, the adhesive layer can quickly solidify, ensuring that the sealing performance of the battery is not affected.

[0065] Furthermore, the mass ratio of polyethylene to polypropylene in the low melting point adhesive layer 124 is 0 - 1:0 - 1. With this design, the physical and chemical properties of the low melting point adhesive layer 124 can be flexibly adjusted according to different application scenarios and safety requirements. For example, by changing the mass ratio of polyethylene and 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 requirements of different types of batteries in terms of thermal stability, mechanical strength, and safety performance.

[0066] Further, 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. The introduction of these modified polymers can further improve the thermal stability and chemical stability of the low melting point adhesive layer 124, while enhancing its adhesion performance with other parts of the battery, ensuring the reliability of the battery under high temperature and harsh environments.

[0067] In addition, the mass ratio of the first polymer to the second polymer is 1:0 - 0.2. Such a ratio design allows for the introduction of an appropriate amount of modified polymer to achieve specific performance optimization while maintaining the basic performance of the low melting point adhesive layer 124. In this way, it can be ensured that the aluminum-plastic film 100 has sufficient mechanical strength and durability while providing thermal stability.

[0068] Figure 4 As can be seen from the top view of the battery prepared by packaging the battery cell 2 with the aluminum-plastic film 100 of the present application, the battery provided by the present application includes the aluminum-plastic film 100 described in any one of the above and the battery cell 2 disposed in the two punching pits 11 of the aluminum-plastic film 100; the battery cell 2 extends with a tab 21, and the tab 21 is bonded to the top sealing area 12 through the tab 21 adhesive layer. Thus, the structural design of the battery ensures that 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 under high temperature conditions, thereby avoiding safety problems caused by excessive internal pressure. Among them, it should be noted that the present application Figure 3 The battery shown is cut to remove the air bag in the aluminum-plastic film 100 as shown in Figure 2 At the same time Figure 2 The encapsulation process of the aluminum-plastic film 100 shown is to fold it in half along the perpendicular bisector of the length direction (X-axis direction) of the aluminum-plastic film 100 so that the two punching pits 11 can assemble the battery cell 2 and seal the battery cell 2 in the punching pits 11 through the top sealing area 12 and the side sealing area 13.

[0069] Further, 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 coated in segments, 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.

[0070] When n*A is too small, the area of the low-melting-point adhesive layer 124 is small and the rupture rate is low, which cannot meet the requirement of rapid rupture in the hot box test, and further causes the function of relieving the 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 the excessive polymer layers lead to glue overflow, and the aluminum layer ruptures during side edge folding, with the risks of liquid leakage and hot box failure.

[0071] In addition, the battery prepared from the aluminum-plastic film of the present application can be any one of a lithium-ion battery, a sodium-ion battery, a zinc-ion battery, a solid-state battery, a vanadium battery, a zirconium battery, etc. in the specific implementation process.

[0072] Specifically, the hot box test process for the battery prepared in the present application is as follows: First, charge the battery to the upper limit voltage at 0.5C (cut-off at 0.02C), and test the initial state of the battery, including voltage, internal resistance, thickness, etc.; then put the battery into an oven, heat it at an initial temperature of 25±3°C, and increase the temperature at a rate of 5±2°C to 130±2°C, and keep it for 60 minutes before the test ends. Judgment criterion: The battery does not catch fire or explode.

[0073] The following further describes the present invention in detail in combination with specific embodiments and the test results of each embodiment for the hot box test, but the embodiments of the present invention are not limited thereto.

[0074] Embodiment 1

[0075] The battery in this embodiment is a lithium-ion soft-pack battery, and the thickness of the prepared battery is 4.2 mm, the width is 65 mm, and the length is 82 mm; among them, the width of the top seal area 12 is 2.4 mm, the width of the side seal area 13 is 6 mm, and the widths of the first seal area 125 and the second seal area 122 are both 1.3 mm.

[0076] Among them, the thickness of the aluminum-plastic film 100 is 103 μm, the thicknesses of the nylon layer 121 and the adhesive layer are both 28 μm, the thickness of the aluminum foil layer 122 is 40 μm, the thickness of the hot-melt adhesive layer 123 is 35 μm, and the melting point of the hot-melt adhesive layer 123 of the aluminum-plastic film 100 is 160°C. The low-melting-point adhesive layer 124 in this embodiment is hot-pressed and pasted on the surface of the hot-melt adhesive layer 123 in the top seal area 12 of the aluminum-plastic film 100 by a solid-state pasting method. The length of the low-melting-point adhesive layer 124 is 3.2 mm, the width is 1.5 mm, and the thickness is 10 μm. Among them, the melting point of the low-melting-point adhesive layer 124 is 96°C, and it is mutually hot-melted with the tab 21 glue of the bare roll core, the hot-melt adhesive layer 123, and the tab 21 glue;

[0077] The low-melting-point adhesive layer 124 in this embodiment is only attached to the top seal area 12, and the number of attached strips is 1; the first polymer for preparing the low-melting-point adhesive layer 124 in this embodiment is made of polyethylene; the second polymer is polymethyl methacrylate; the mass ratio of the first polymer to the second polymer is 1:0.1.

[0078] Example 2

[0079] Different from Example 1, the mass ratio of the first polymer to the second polymer in this example is: 1:0.2; the melting point of the low-melting-point adhesive layer 124 is 100 °C.

[0080] Example 3

[0081] Different from Example 1, the first polymer in this example is a mixture of polyethylene and polypropylene; among them, the mass ratio of polyethylene to polypropylene is: 1:0.5;

[0082] The melting point of the low-melting-point adhesive layer 124 is 105 °C.

[0083] Example 4

[0084] Different from Example 1, the first polymer in this example is a mixture of polyethylene and polypropylene; among them, the mass ratio of polyethylene to polypropylene is: 1:1;

[0085] The melting point of the low-melting-point adhesive layer 124 is 110 °C.

[0086] Example 5

[0087] Different from Example 1, the first polymer in this example is a mixture of polyethylene and polypropylene; among them, the mass ratio of polyethylene to polypropylene is: 1:1;

[0088] 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;

[0089] The melting point of the low-melting-point adhesive layer 124 is 114 °C.

[0090] Example 6

[0091] Different from Example 1, the first polymer in this example is polypropylene; the second polymer is polymethyl methacrylate;

[0092] The melting point of the low-melting-point adhesive layer 124 is 123 °C.

[0093] Example 7

[0094] Different from Example 1, the first polymer in this example is polypropylene; the second polymer is polymethyl methacrylate; the mass ratio of the first polymer to the second polymer is 1:0.2;

[0095] The melting point of the low-melting-point adhesive layer 124 is 130 °C.

[0096] Comparative Example 1

[0097] Different from Example 1, there is no low melting point adhesive layer 124 in this comparative example.

[0098] Comparative Example 2

[0099] Different from Example 1, the first polymer of the low melting point adhesive layer 124 in this comparative example is polypropylene and there is no second polymer.

[0100] Comparative Example 3

[0101] Different from Example 1, the first polymer of the low melting point adhesive layer 124 in this comparative example is not polypropylene, and the second polymer is polymethyl methacrylate.

[0102] According to the hot box test on the above Examples 1-7 and Comparative Example 1, the results are shown in Table 1 below.

[0103]

[0104] Table 1

[0105] As can be seen from Table 1, the aluminum-plastic film 100 of the present invention shows excellent performance in the hot box test. Among Examples 1 to 7, all the batteries passed the hot box test, and the peak temperatures of the batteries were all within an acceptable range. This indicates that by reasonably 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 were all lower than 135°C in the hot box test, meeting the requirements for the safety of the battery in a high temperature environment.

[0106] Further analysis shows that the passing rates of the batteries in Examples 1 to 7 in the hot box test were all 100%, which indicates that the introduction of the low melting point adhesive layer 124 significantly improves the safety performance of the battery, especially in a high temperature environment. In Comparative Example 1, since the low melting point adhesive layer 124 was missing, all the batteries failed the hot box test. In Comparative Example 2, only half of them passed specifically 5 out of 10 passed, and Comparative Example 3 passed only one more than Comparative Example 2. This further proves the importance of the low melting point adhesive layer 124 of the present application for the safety performance of the battery.

[0107] In terms of the size position parameters, the batteries in Examples 1 to 7 all met the conditions of n*A / c or n*A / d, which indicates that the length and number of segments of the low melting point adhesive layer 124 are in proper proportion to the size of the battery, ensuring both a sufficient area of the low melting point adhesive layer 124 to meet the rapid breakage requirement in the hot box test and avoiding problems such as glue overflow and aluminum layer rupture that may be caused by too long a low melting point adhesive layer 124 or too many segments.

[0108] In addition, in Examples 2-7, Comparative Example 2, and Comparative Example 3, the material composition of the low-melting-point adhesive layer 124 was changed based on Example 1. The results of the hot box tests for the examples and comparative examples showed that when the material composition was changed, the low-melting-point adhesive layer 124 could pass the hot box within the defined melting point range of 90-130°C. However, the melting points of the first polymer or the pure second polymer were too high, failing to play the role of weakening the encapsulation, resulting in the failure of the hot box.

[0109] In addition, in Examples 1-7 of the present application, by adjusting the melting point of the low-melting-point adhesive layer 124, the thermal stability of the battery was further optimized. By comparing the melting points of the low-melting-point adhesive layer 124 in Examples 1 to 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 shows that by selecting an appropriate melting point, the thermal stability of the battery can be finely adjusted according to different application scenarios and safety requirements. For example, for batteries that need to work in a higher temperature environment, the melting point of the low-melting-point adhesive layer 124 can be appropriately increased to ensure the safety performance of the battery under extreme conditions. At the same time, the selection of the melting point also needs to consider the sealing performance of the battery at normal operating temperatures to avoid affecting the normal use of the battery due to too high a melting point.

[0110] In summary, the aluminum-plastic film 100 of the present invention significantly improves the safety performance of the battery in a high-temperature environment by optimizing the physical and chemical properties of the low-melting-point adhesive layer 124, providing a new solution for the safe use of the battery.

[0111] Example 8

[0112] Different from Example 1: In this example, the low-melting-point adhesive layer 124 was coated on the surface of the hot melt adhesive by a melt coating method.

[0113] Example 9

[0114] Different from Example 1: In this example, the low-melting-point adhesive layer 124 was coated on the surface of the hot melt adhesive by a solution coating method.

[0115] According to the hot box tests on Example 1 and Examples 8-9 above, the results are shown in Table 2 below.

[0116]

[0117] Table 2

[0118] From the data in Table 2, it can be seen that the batteries in Example 8 and Example 9 also showed good performance in the hot box test, with a passing rate of 100% for both, and the peak temperatures were within an acceptable range. This shows that whether by the melt coating method or the solution coating method, the low-melting-point adhesive layer 124 can effectively bond with the hot melt adhesive layer 123 to ensure the safety performance of the battery in a high-temperature environment. In particular, in Example 9, the solution coating method was used, and its peak temperature only increased slightly compared with that in Example 1 and Example 8, indicating that different coating methods have limited effects on the battery performance, but both can meet the requirements of battery safety. In addition, the size and position parameters of Example 8 and Example 9 both meet the conditions of n*A / c or n*A / d, further proving the adaptability of the coating method of the low-melting-point adhesive layer 124 to the battery size and safety performance. In summary, the aluminum-plastic film 100 of the present invention provides a flexible and safe encapsulation solution for the battery through different coating methods, ensuring the stability and reliability of the battery in various environments.

[0119] Example 10

[0120] Different from Example 1: In this example, the low-melting-point adhesive layer 124 is arranged in the bottom sealing area, and the bottom sealing area is correspondingly arranged along the battery length direction (X-axis direction) with the top sealing area 12.

[0121] Example 11

[0122] Different from Example 1: In this example, the low-melting-point adhesive layer 124 is arranged in the side sealing area 13 without an air bag.

[0123] Example 12

[0124] Different from Example 1: In this example, the low-melting-point adhesive layer 124 is arranged in the side sealing area 13 with an air bag.

[0125] Example 13

[0126] Different from Example 1: In this example, the low-melting-point adhesive layer 124 is arranged 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.

[0127] Example 14

[0128] Different from Example 1: In this example, the low-melting-point adhesive layer 124 is arranged in both the side sealing area 13 with an air bag and the side sealing area 13 without an air bag; the number n of the low-melting-point adhesive layer 124 is 2.

[0129] Example 15

[0130] Different from Example 1: In this example, the low-melting-point adhesive layer 124 is arranged in both the bottom sealing area and the side sealing area 13 without an air bag; the number n of the low-melting-point adhesive layer 124 is 2.

[0131] Example 16

[0132] Different from Example 1: In this example, the length of the low melting point adhesive layer 124 is 0.65 mm.

[0133] Example 17

[0134] Different from Example 1: In this example, the length of the low melting point adhesive layer 124 is 0.8 mm and it is arranged in the side sealing area 13 without an air bag.

[0135] Example 18

[0136] Different from Example 1: In this example, the length of the low melting point adhesive layer 124 is 1 mm.

[0137] Comparative Example 4

[0138] Different from Example 1: In this comparative example, the low melting point adhesive layer 124 is arranged at a position in the non-sealing area.

[0139] According to the hot box tests on Example 1 and Examples 10 - 18 above, the results are as follows

[0140] As shown in Table 3.

[0141]

[0142] Table 3

[0143] As can be seen from the data in Table 3, the passing rates of the batteries in Examples 16 to 18 in the hot box test have decreased, 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 be able to provide sufficient sealing area to meet the rapid breakage requirement in the hot box test, resulting in a reduction in the safety of the battery in a high-temperature environment. Especially in Example 18, the length of the low melting point adhesive layer 124 is 1 mm, and its passing rate is only 70%, and the peak temperature reaches 160 °C, which indicates that too short a length of the low melting point adhesive layer 124 may not be able to meet the safety requirements of the battery in a high-temperature environment. Although the passing rates of the batteries in Examples 16 and 17 are 100%, the peak temperatures reach 140 °C and 154 °C respectively, which shows that the length of the low melting point adhesive layer 124 has a certain influence on the thermal stability of the battery. In Comparative Example 4, the low melting point adhesive layer 124 is not coated in any of the sealing areas, so no technical effect is produced.

[0144] Therefore, when designing the low melting point adhesive layer 124, it is necessary to comprehensively consider its length, melting point and coating method to ensure the safety performance of the battery in various environments. Through reasonable design, the safety and reliability of the battery in a high-temperature environment can be ensured to meet the requirements of different application scenarios.

[0145] Example 19

[0146] Different from Example 1: In this example, the coating quantity of the low melting point adhesive layer 124 is: n = 15.

[0147] Example 20

[0148] Different from Example 1: In this example, the coating quantity of the low melting point adhesive layer 124 is: n = 20.

[0149] Example 21

[0150] Different from Example 1: In this example, the coating quantity of the low melting point adhesive layer 124 is: n = 25; the low melting point adhesive layer 124 is arranged in the airbagless side seal area 13.

[0151] Example 22

[0152] Different from Example 1: In this example, the length of the low melting point adhesive layer 124 is 65 mm.

[0153] Example 23

[0154] Different from 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 arranged in the airbagless side seal area 13.

[0155] Example 24

[0156] Different from Example 1: In this example, the thickness of the low melting point adhesive layer 124 is 1 mm.

[0157] According to the hot box tests on Example 1 and Examples 19 - 25 above, the results are as follows

[0158] as shown in Table 4.

[0159]

[0160] Table 4

[0161] As can be seen from the data in Table 4, the batteries in Examples 19 to 23 showed different performances in the hot box test. The passing rates of the batteries in Examples 19 and 20 were both 100%, but the peak temperature increased slightly with the increase in the coating quantity of the low melting point adhesive layer 124. This indicates that increasing the quantity of the low melting point adhesive layer 124 can improve the thermal stability of the battery to a certain extent, but at the same time, it will also cause the increase in the peak temperature of the battery. The passing rate of the battery in Example 21 was also 100%, but the peak temperature further increased to 136 °C, which may be related to the fact that the low melting point adhesive layer 124 is arranged in the airbagless side seal area 13, and more low melting point adhesive layer 124 may be required in this area to ensure the sealing effect.

[0162] The passing rates of the batteries in Examples 22 and 23 are 90% and 100% respectively, and the peak temperatures are 141 °C and 130 °C respectively, indicating that the length of the low-melting-point adhesive layer 124 has a significant impact on the thermal stability of the battery. In particular, when the length of the low-melting-point adhesive layer 124 is too long, it may cause a decrease in the performance of the battery during the hot box test. In addition, when 0.02 ≤ n*A / c or n*A / d ≤ 1, the hot box can pass. When n*A / c or n*A / d < 0.02, the weakening of the encapsulation by the low-melting-point adhesive layer 124 is not obvious, and the hot box fails. When n*A / c or n*A / d > 1, excessive polymer substances cause glue overflow during the heat sealing of the battery core 2, and the aluminum foil layer 122 ruptures, resulting in a probability of hot box failure.

[0163] The passing rate of the battery in Example 24 is 80%, and the peak temperature is as high as 163 °C, indicating that an increase in the thickness of the low-melting-point adhesive layer 124 does not necessarily lead to better thermal stability, but may instead 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 the best battery safety performance.

[0164] Example 25

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

[0166] Example 26

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

[0168] Example 27

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

[0170] Example 28

[0171] Different from 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 seal area 13 without an air bag.

[0172] Example 29

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

[0174] Example 30

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

[0176] Example 31

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

[0178] According to the hot box tests on Example 1 and Examples 26 - 31 above, the results are as follows

[0179] as shown in Table 5.

[0180]

[0181] Table 5

[0182] As shown in the data of Table 5, the batteries of Examples 25 to 31 showed different performances in the hot box test. The passing rate of the battery in Example 25 remained at 100%, and the peak temperature slightly increased to 131 °C, indicating that appropriately increasing the width of the low-melting-point adhesive layer 124 can provide a better sealing effect without significantly affecting the thermal stability of the battery. The changes in the passing rate and peak temperature of the batteries in Examples 26 to 31 showed the influence of the thickness of the low-melting-point adhesive layer 124 on the battery performance.

[0183] Among them, the passing rates of the batteries in Examples 26 and 27 decreased slightly to 90% respectively, while the peak temperatures reached 148 °C and 145 °C respectively, which may be related to the reduced heat conduction efficiency caused by the too thick low-melting-point adhesive layer 124. The passing rates of the batteries in Examples 28 to 31 were all 100%, but the peak temperature increased with the increase of the thickness, indicating 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 overly thick adhesive layer may lead to a decline in the performance of the battery at high temperatures.

[0184] In addition, Examples 24 and 25 changed the width B of the low-melting-point adhesive layer 124 on the basis of Example 1. When B ≥ b, the hot box can pass. When the width B of the low-melting-point adhesive layer 124 < b, the sealing weakening effect is not obvious, and there is a probability of hot box failure.

[0185] Examples 26 - 31 changed the thickness C of the low-melting-point adhesive layer 124 on the basis of Example 1. When C is within the patent-defined thickness, that is, when C / e ≥ 0.2, the hot box can pass. When C / e < 0.2, due to the too thin low-melting-point adhesive layer 124, the sealing weakening effect is not obvious, and there is a probability of hot box failure.

[0186] Therefore, when designing the low-melting-point adhesive layer 124, it is necessary to comprehensively consider its width, length, and thickness to ensure the safety performance and thermal stability of the battery in various environments. Through reasonable design, the safety and reliability of the battery in high-temperature environments can be ensured to meet the requirements of different application scenarios.

[0187] Based on the comprehensive information shown in Tables 1 - 5, the low-melting-point adhesive layer 124 can significantly improve the passing rate of the hot box.

[0188] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. An aluminum-plastic film, characterized in that: It comprises two symmetrically arranged scouring pits (11) (11), a top sealing area (12) arranged along one side in the width direction of the scouring pit (11), and a side sealing area (13) arranged along the length direction of the scouring pit (11); The side sealing area (13) and / or the top sealing area (12) are sequentially provided with a nylon layer (121), an aluminum foil layer (122), a hot melt adhesive layer (123) and a low melting point adhesive layer (124) along the thickness direction thereof; the nylon layer (121) and the aluminum foil layer (122) are bonded to each other via an adhesive layer, and the aluminum foil layer (122) and the hot melt adhesive layer (123) are bonded to each other via 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); and at the same time, the low melting point adhesive layer (124) is coated on the surface of the hot melt adhesive layer (123) in the form of segmented coating or continuous coating; The melting point of the hot melt adhesive layer (123) is 140°C-170°C, and the melting point of the low melting point adhesive layer (124) is 90°C-130°C.

2. The aluminum-plastic film 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, wherein 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. The aluminum-plastic film 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° C.-125° C.; The number average molecular weight of the polypropylene is 40,000-100,000, and the melting point is 100° C.-160° C.

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

5. The aluminum-plastic film according to claim 2, characterized in that: 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.

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

7. The aluminum-plastic film according to claim 1, characterized in that: 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.

8. The aluminum-plastic film according to claim 7, 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 (122); the widths of the top sealing area (12) and the side sealing area (13) are both a, the widths of the first sealing area (125) and the second sealing area (122) are both b, and the width of the low melting point adhesive layer (124) is B; Among them, a, b and B satisfy b≤B≤a.

9. A battery, characterized in that: It comprises the aluminum-plastic film as claimed in any one of claims 1 to 8 and a battery cell (2) arranged in two punching holes (11) of the aluminum-plastic film; The battery cell (2) is provided with a pole lug (21) extending therefrom, and the pole lug (21) is bonded to the top sealing area (12) via a pole lug adhesive layer (211).

10. A battery according to claim 9, 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 applied in sections, the length A of the low melting point adhesive layer (124) represents the length of each section of the low melting point adhesive layer (124). The number of sections of the low melting point adhesive layer (124) is n. When the low melting point adhesive layer (124) is applied continuously, the number of sections n=1. Among them, A, c, d, and n satisfy 0.02≤n*A / c or n*A / d≤1.

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