A lithium-ion battery

Abstract

This invention provides a lithium-ion battery, comprising a battery cell and an aluminum-plastic film encapsulating the battery cell. The battery cell includes a positive electrode, a separator, a negative electrode, and an electrolyte. The shrinkage rate of the separator is Y%. The aluminum-plastic film comprises a polypropylene film, an aluminum foil, and a composite nylon layer arranged sequentially. Nano-metals are distributed in the composite nylon layer, with a particle size of 35nm to 75nm. The amount of nano-metals added to the composite nylon layer is Zwt%, and the relationship between Y and Z satisfies 0.18≤Y / Z≤1.45. The lithium-ion battery of this invention can quickly dissipate the chemical heat generated inside the battery cell due to temperature rise, delay the internal temperature rise of the battery cell, and improve the heat box pass rate.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, and specifically relates to a lithium-ion battery. Background Technology

[0002] Soft-pack lithium-ion batteries are widely used in various digital products and mobile devices due to their high energy density, low self-discharge rate, wide operating temperature range, and environmental friendliness. With the continuous upgrading of electronic products, especially the development of portable mobile communication tools, these devices have evolved from simple text and voice communication to multimedia communication and entertainment devices integrating text, voice, images, and video. This transformation has greatly increased the functional complexity of electronic products, leading to a significant increase in their power consumption.

[0003] To meet the demands for higher battery energy density, researchers are constantly exploring and applying novel battery materials. Silicon, due to its high specific capacity, has been widely studied as a dopant in anode materials. Silicon-doped anodes are considered one of the effective methods to improve battery energy density. However, with the increase in silicon doping ratio and operating voltage, battery safety faces serious challenges. For example, at high voltages, anode batteries containing 10% silicon-carbon exhibit significant safety hazards in thermal abuse tests. Increased external temperature leads to violent chemical reactions within the cell, causing the SEI film (solid electrolyte interface film) of the silicon anode to rapidly fail. The heat generated by the reaction between the exposed silicon anode surface and the electrolyte cannot be effectively dissipated, resulting in a sharp rise in the internal temperature of the cell. Ultimately, this heat accumulation can lead to the decomposition of lithium cobalt oxide, potentially causing the cell to catch fire or explode—a situation more likely to occur than with traditional graphite anode batteries.

[0004] Despite significant progress in energy density, pouch lithium batteries still fall short in thermal management. Heat dissipation remains a key bottleneck limiting their further development, impacting battery safety and stability. Therefore, improving the heat dissipation performance of pouch lithium batteries is a pressing issue that needs to be addressed. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides a lithium-ion battery that can promptly conduct heat to the outside of the cell when the internal temperature rises, thus reducing the heat exposure of the separator inside the cell and achieving a safety objective.

[0006] A first aspect of the present invention provides a lithium-ion battery, comprising a cell and an aluminum-plastic film encapsulating the cell. The cell includes a positive electrode, a separator, a negative electrode, and an electrolyte. The separator has a shrinkage rate of Y%. The aluminum-plastic film comprises a polypropylene film, an aluminum foil, and a composite nylon layer arranged sequentially. Nano-metals are distributed in the composite nylon layer. The nano-metals have a particle size of 35 nm to 75 nm. The amount of nano-metals added to the composite nylon layer is Z wt%. Y and Z satisfy the relationship 0.18 ≤ Y / Z ≤ 1.45.

[0007] One of the technical solutions of the present invention concerning aluminum-plastic film has at least the following beneficial effects:

[0008] During thermal abuse testing of high-voltage silicon-carbon (10% SiC) lithium batteries, external heating can cause chemical reactions within the cell, leading to a rapid reaction of the silicon anode SEI film. The exposed silicon anode surface then generates heat through reaction with the electrolyte. This accumulated heat, unable to dissipate, causes a rapid rise in the internal temperature of the cell, eventually leading to the decomposition of lithium cobalt oxide, resulting in cell fire or explosion and test failure. This is more prone to failure than with traditional graphite anodes. The rapid temperature rise can be mitigated by increasing heat dissipation on the cell surface to release the internal temperature. The shrinkage rate of the separator is correlated with the coating thickness; a lower shrinkage rate results in better safety performance, ensuring minimal shrinkage in the TD direction (perpendicular to the length direction) above 130°C, thus preventing short circuits between the positive and negative electrodes. However, for separators of the same thickness, the shrinkage rate is inversely proportional to the manufacturing cost; a lower shrinkage rate requires a thicker ceramic layer or more optimized process parameters. This invention utilizes an aluminum-plastic film containing nano-metals, which can accommodate separators with higher shrinkage rates. Specifically, the aluminum-plastic film containing nano-metals of the present invention can be used in conjunction with a cheaper separator (with a larger shrinkage rate in the 0.5H TD direction at 130℃). The shrinkage rate of the separator is Y%, and the amount of nano-metals added in the composite nylon layer is Zwt%. The relationship between Y and Z satisfies 0.18≤Y / Z≤1.45. When the temperature rises inside the battery cell, heat can be conducted to the outside of the battery cell in a timely manner, so that the separator is less heated inside the battery cell, thus achieving the purpose of safety.

[0009] Based on the simplified model of heat generation and dissipation balance during battery operation, Q-δ=mCp.m(dT / dt), where Q is the battery's heat generation rate, δ is the heat dissipation rate, m is the mass, Cp.m is the specific heat capacity, T is the temperature, and t is the time. A higher heat dissipation rate maintains balance in the equation, making the material less prone to thermal failure and combustion. This paper utilizes high thermal conductivity nano-metal doping incorporated into the nylon layer to rapidly dissipate the internal reaction heat generated during the temperature rise of the battery cell in the test chamber, increasing the heat dissipation rate and improving the heat chamber pass rate of the silicon anode.

[0010] According to some embodiments of the present invention, the shrinkage rate Y% of the separator ranges from 0.9% to 4.5%.

[0011] According to some embodiments of the present invention, the shrinkage rate Y% of the separator can be any value or a range formed by any two of the following: 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, and 4.5%, for example, 2.0% to 4.0%.

[0012] According to some embodiments of the present invention, the amount of nano-metal added to the composite nylon layer, Zwt%, ranges from 1% to 5%.

[0013] According to some embodiments of the present invention, the amount of nano-metal added to the composite nylon layer, Zwt%, can range from 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, to 2.8%. The percentage can be any value from 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, or 5.0%, or a range of any two of these values, such as 3.0% to 5.0%.

[0014] According to some embodiments of the present invention, the isolation membrane comprises a base layer and a surface layer disposed sequentially.

[0015] According to some embodiments of the present invention, the material of the base layer includes PP or PE.

[0016] According to some embodiments of the present invention, the surface layer is made of PVDF and alumina ceramic.

[0017] According to some embodiments of the present invention, the outer surface of the composite nylon layer is provided with a plurality of strip-shaped protrusions.

[0018] The strip-shaped protrusions can further increase the heat dissipation area.

[0019] According to some embodiments of the present invention, the line width of the strip-shaped protrusion is 0.1 mm to 0.3 mm.

[0020] According to some embodiments of the present invention, the height of the strip-shaped protrusion is 4 micrometers to 8 micrometers.

[0021] According to some embodiments of the present invention, the height of the strip-shaped protrusion is any value of 4 micrometers, 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, or a range formed by any combination of both.

[0022] According to some embodiments of the present invention, the strip-shaped protrusions are parallel to each other.

[0023] According to some embodiments of the present invention, the spacing between the strip-shaped protrusions is 0.5 mm to 2 mm.

[0024] According to some embodiments of the present invention, the spacing of the strip-shaped protrusions is any value of 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, or a range formed by any two of them.

[0025] According to some embodiments of the present invention, the strip-shaped protrusions are sinusoidal in shape.

[0026] According to some embodiments of the present invention, the cross-section of the strip-shaped protrusion includes at least one of arch, triangle and rectangle.

[0027] According to some embodiments of the present invention, the thickness of the polypropylene film is 30 micrometers to 80 micrometers.

[0028] According to some embodiments of the present invention, the thickness of the polypropylene film is any value of 30 micrometers, 40 micrometers, 50 micrometers, 60 micrometers, 70 micrometers, 80 micrometers, or a range of any two of these values.

[0029] According to some embodiments of the present invention, the thickness of the aluminum foil is 20 micrometers to 40 micrometers.

[0030] According to some embodiments of the present invention, the thickness of the aluminum foil is any value of 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, or a range formed by any combination of both.

[0031] According to some embodiments of the present invention, the thickness of the composite nylon layer is 20 micrometers to 40 micrometers.

[0032] According to some embodiments of the present invention, the thickness of the composite nylon layer is any value of 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, or a range formed by any combination of both.

[0033] According to some embodiments of the present invention, a polyurethane adhesive layer is provided between the polypropylene film and the aluminum foil.

[0034] According to some embodiments of the present invention, the thickness of the polyurethane adhesive layer is 1 micrometer to 3 micrometers.

[0035] According to some embodiments of the present invention, the thickness of the polyurethane adhesive layer is any value of 1 micrometer, 1.5 micrometer, 2 micrometer, 2.5 micrometer, 3 micrometer, or a range formed by any combination of both.

[0036] According to some embodiments of the present invention, a polyethylene naphthalate adhesive layer is provided between the aluminum foil and the composite nylon layer.

[0037] According to some embodiments of the present invention, the thickness of the polyethylene naphthalate adhesive layer is 1 micrometer to 3 micrometers.

[0038] According to some embodiments of the present invention, the thickness of the polyethylene naphthalate adhesive layer is any value of 1 micrometer, 1.5 micrometer, 2 micrometer, 2.5 micrometer, 3 micrometer, or a range formed by any combination of both.

[0039] According to some embodiments of the present invention, the nanometal includes nanosilver or nanocopper.

[0040] The thermal conductivity of silver is 429 W / (m·K), copper is typically 385 W / (m·K), and aluminum is 237 W / (m·K). The thermal conductivity of the adhesive layer is generally less than 1 W / (m·K).

[0041] According to some embodiments of the present invention, the morphology of the nanometal includes nanosheets or nanoparticles.

[0042] According to some embodiments of the present invention, the method for preparing the aluminum-plastic film includes the steps of co-molding the nano-metal and nylon particles to obtain a composite nylon layer, and then compounding the polypropylene film, aluminum foil and the composite nylon layer. Attached Figure Description

[0043] Figure 1 This is a cross-sectional structural diagram of the aluminum-plastic film of Example 1.

[0044] Figure 2 This is a top view of an aluminum-plastic film with a convex sine wave shape.

[0045] Figure 3 This is a top view of an aluminum-plastic film with raised lines forming parallel lines. Detailed Implementation

[0046] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0047] In a first aspect, in some embodiments of the present invention, a lithium-ion battery is provided, comprising a battery cell and an aluminum-plastic film encapsulating the battery cell. The battery cell includes a positive electrode, a separator, a negative electrode, and an electrolyte. The shrinkage rate of the separator is Y%. The aluminum-plastic film includes a polypropylene film, an aluminum foil, and a composite nylon layer arranged sequentially. Nano-metals are distributed in the composite nylon layer. The particle size of the nano-metals is 35 nm to 75 nm. The amount of nano-metals added in the composite nylon layer is Z wt%. Y and Z satisfy the relationship 0.18 ≤ Y / Z ≤ 1.45.

[0048] It is understandable that during thermal abuse testing of high-voltage silicon-carbon (10% SiC) lithium batteries, external heating can cause chemical reactions within the cell, leading to a rapid reaction of the silicon anode SEI film. The exposed silicon anode surface then generates heat with the electrolyte. This accumulated heat, unable to dissipate, causes a rapid rise in the internal temperature of the cell, eventually leading to the decomposition of lithium cobalt oxide, resulting in cell fire or explosion and test failure. This is more prone to failure than with traditional graphite anodes. The rapid temperature rise can be addressed by increasing heat dissipation on the cell surface to release the internal temperature. The shrinkage rate of the separator is related to the coating thickness; a lower shrinkage rate results in better safety performance, ensuring a low shrinkage rate in the TD direction (perpendicular to the length direction) above 130°C, preventing short circuits between the positive and negative electrodes. However, for separators of the same thickness, the shrinkage rate is inversely proportional to the manufacturing cost; a lower shrinkage rate requires a thicker ceramic layer or more optimized process parameters. This invention uses an aluminum-plastic film containing nano-metals, which can be matched with a separator with a higher shrinkage rate. Specifically, the aluminum-plastic film containing nano-metals of the present invention can be used in conjunction with a cheaper separator (with a larger shrinkage rate in the 0.5H TD direction at 130℃). The shrinkage rate of the separator is Y%, and the amount of nano-metals added in the composite nylon layer is Zwt%. The relationship between Y and Z satisfies 0.18≤Y / Z≤1.45. When the temperature rises inside the battery cell, heat can be conducted to the outside of the battery cell in a timely manner, so that the separator is less heated inside the battery cell, thus achieving the purpose of safety.

[0049] Based on the simplified model of heat generation and dissipation balance during battery operation, Q-δ=mCp.m(dT / dt), where Q is the battery's heat generation rate, δ is the heat dissipation rate, m is the mass, Cp.m is the specific heat capacity, T is the temperature, and t is the time. A higher heat dissipation rate maintains balance in the equation, making the material less prone to thermal failure and combustion. This paper utilizes high thermal conductivity nano-metal doping incorporated into the nylon layer to rapidly dissipate the internal reaction heat generated during the temperature rise of the battery cell in the test chamber, increasing the heat dissipation rate and improving the heat chamber pass rate of the silicon anode.

[0050] In conjunction with the first aspect, in some embodiments of the present invention, the shrinkage rate Y% of the separator is in the range of 0.9% to 4.5%.

[0051] In conjunction with the first aspect, in some embodiments of the present invention, the shrinkage rate Y% of the separator can be any value or a range formed by any two of the following: 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, and 4.5%, for example, 2.0% to 4.0%.

[0052] In conjunction with the first aspect, in some embodiments of the present invention, the amount of nano-metal added in the composite nylon layer, Zwt%, ranges from 1% to 5%.

[0053] In conjunction with the first aspect, in some embodiments of the present invention, the value range of the amount of nano-metal added in the composite nylon layer, Zwt%, can be 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%. The percentage is any value or a range of any two of the following: 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, and 5.0%, for example, 3.0% to 5.0%.

[0054] In conjunction with the first aspect, in some embodiments of the present invention, the isolation membrane includes a base layer and a surface layer disposed sequentially.

[0055] In conjunction with the first aspect, in some embodiments of the present invention, the base material includes PP or PE.

[0056] In conjunction with the first aspect, in some embodiments of the present invention, the surface layer is made of PVDF and alumina ceramic.

[0057] In conjunction with the first aspect, in some embodiments of the present invention, the outer surface of the composite nylon layer is provided with a plurality of strip-shaped protrusions.

[0058] In conjunction with the first aspect, in some embodiments of the invention, the cross-section of the strip-shaped protrusion includes at least one of an arch, a triangle, and a rectangle.

[0059] The strip-shaped protrusions can further increase the heat dissipation area.

[0060] In conjunction with the first aspect, in some embodiments of the present invention, the line width of the strip-shaped protrusion is 0.1 mm to 0.3 mm.

[0061] The strip-shaped protrusions increase the effective heat dissipation area of ​​the membrane surface, enhancing heat dissipation and thus improving the overall heat dissipation efficiency of the battery cell. This protrusion shape helps to evenly distribute the heat generated on the cell surface, preventing heat accumulation in localized areas and reducing the risk of overheating. The strip-shaped protrusions increase the contact area between the aluminum-plastic membrane and the battery cell, improving thermal conductivity and ensuring more efficient heat transfer. These protrusions also enhance the structural strength of the membrane, making it less prone to deformation or failure at high temperatures, thus improving the overall reliability of the membrane. By increasing heat dissipation channels, these protrusions help accelerate the release of heat inside the battery cell, reducing the rate of temperature rise during thermal abuse testing and improving battery safety and thermal stability.

[0062] In conjunction with the first aspect, in some embodiments of the present invention, the height of the strip-shaped protrusion is 4 micrometers to 8 micrometers.

[0063] Strip-shaped protrusions help disperse and evenly distribute heat, reducing localized heat accumulation, improving overall heat dissipation, and slowing down the rate of temperature rise inside the battery. By increasing the microscopic irregularities on the membrane surface, strip-shaped protrusions can promote heat conduction on the membrane surface, improving the efficiency of heat transfer from inside the cell to the outside. Strip-shaped protrusions can form a tiny air layer between the membrane and the external environment. Although this air layer is thin, it helps improve the membrane's heat exchange performance, effectively assisting in the dissipation of heat from inside the cell. These protrusions provide structural support on the membrane surface, enhancing the overall stability of the membrane and making it less prone to deformation or failure under high-temperature environments. In the thermal abuse testing of high-voltage silicon-carbon anode lithium batteries, these highly defined strip-shaped protrusions help release the internally generated reaction heat to the outside more quickly, improving the battery's thermal runaway rate and reducing the risk of fire or explosion due to overheating.

[0064] In conjunction with the first aspect, in some embodiments of the present invention, the height of the strip-shaped protrusion is any value of 4 micrometers, 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, or a range formed by any two of them.

[0065] In conjunction with the first aspect, in some embodiments of the invention, the strip-shaped protrusions are parallel to each other.

[0066] The parallel strip-shaped protrusions create a regular heat dissipation surface, which helps to evenly distribute heat on the battery surface, avoiding localized overheating and improving overall heat dissipation efficiency. The parallel strip-shaped protrusions effectively form multiple heat conduction channels, allowing heat to be conducted to the membrane surface more quickly along these channels, promoting rapid heat release. This design reduces thermal resistance caused by surface unevenness or structural irregularities, ensuring that heat is guided and dissipated through a more intuitive path. The arrangement of the parallel strip-shaped protrusions optimizes the effective heat dissipation area of ​​the membrane. Compared to other irregular structures, the parallel arrangement helps to increase the contact area between the membrane and the surrounding air, thereby improving heat dissipation efficiency. The parallel arrangement of the strip-shaped protrusions also increases the overall mechanical stability of the membrane, making it less prone to deformation or damage under high temperatures and thermal shock, ensuring stable performance over a long period. The parallel design of the strip-shaped protrusions forms an ordered heat exchange structure on the membrane surface, helping to optimize heat conduction and convection, and improving heat exchange efficiency. Therefore, the parallel strip-shaped protrusions make the aluminum-plastic film more efficient in heat dissipation and thermal management, better able to cope with the thermal abuse of high-voltage silicon-carbon anode lithium batteries, and improve the safety and performance of the battery.

[0067] In conjunction with the first aspect, in some embodiments of the present invention, the spacing between the strip-shaped protrusions is 0.5 mm to 2 mm.

[0068] In conjunction with the first aspect, in some embodiments of the present invention, the spacing of the strip-shaped protrusions is any value of 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, or a range formed by any two of them.

[0069] In conjunction with the first aspect, in some embodiments of the present invention, the strip-shaped protrusions are sinusoidal in shape.

[0070] The raised structure of the sinusoidal waveform effectively increases the contact area. Compared to a straight line or plane, the waveform structure provides more heat dissipation surface, helping to improve heat dissipation efficiency. The sinusoidal waveform also allows for a more uniform distribution of heat flow across the membrane surface, reducing localized heat concentration and helping to prevent hotspot formation, thus improving overall heat dissipation. Furthermore, the waveform design promotes natural air convection, increasing the rate of heat exchange and helping to remove heat from the membrane surface more quickly. The sinusoidal waveform structure improves the overall mechanical stability of the membrane, preventing deformation or cracking due to temperature changes and enhancing membrane durability. The waveform design also reduces heat conduction resistance within the membrane, allowing heat to be released more effectively through the membrane surface, thereby improving heat dissipation efficiency. The raised structure of the sinusoidal waveform helps to even out heat dissipation, reducing the likelihood of hot spots and ensuring consistent heat dissipation across the membrane surface.

[0071] In conjunction with the first aspect, in some embodiments of the present invention, the thickness of the polypropylene film is 30 micrometers to 80 micrometers.

[0072] First, an appropriate thickness provides sufficient mechanical strength and tear resistance, ensuring the aluminum-plastic film remains stable in practical applications and is not easily damaged or failed. Second, an appropriate thickness helps improve the barrier properties against moisture and gases, protecting the internal battery materials from external environmental influences and extending battery life. Third, polypropylene film has good thermal stability; a moderate thickness can effectively withstand thermal stress, reducing deformation or degradation under high-temperature conditions, thus ensuring the stable performance of the aluminum-plastic film. Fourth, a suitable thickness helps achieve uniform material distribution during co-molding or other molding processes, ensuring the structural consistency and performance reliability of the final product. Therefore, selecting a polypropylene film thickness of 30 to 80 micrometers can bring comprehensive advantages in terms of enhanced material strength, barrier properties, thermal stability, and processing performance, thereby improving the overall application effect of aluminum-plastic film in lithium batteries.

[0073] In conjunction with the first aspect, in some embodiments of the present invention, the thickness of the polypropylene film is any value of 30 micrometers, 40 micrometers, 50 micrometers, 60 micrometers, 70 micrometers, 80 micrometers, or a range formed by any combination of both.

[0074] In conjunction with the first aspect, in some embodiments of the present invention, the thickness of the aluminum foil is 20 micrometers to 40 micrometers.

[0075] As a key layer in aluminum-plastic film, aluminum foil plays a crucial role in providing excellent gas and water vapor insulation. A thickness of 20 to 40 micrometers ensures that the aluminum foil effectively isolates external moisture and gases, protecting the internal chemicals and electrolyte of the battery and extending its lifespan. This thickness range also demonstrates excellent mechanical strength. It resists external physical pressure, impacts, or compression, maintaining the overall structural stability of the battery casing and preventing deformation or breakage during transportation and use. Furthermore, aluminum foil possesses good thermal conductivity. A thickness of 20 to 40 micrometers provides adequate thermal conductivity, allowing the battery to dissipate heat more effectively at high temperatures. While the thermal conductivity of aluminum foil is not as outstanding as that of nanometals, within this thickness range, it helps regulate the internal temperature of the battery, preventing overheating. In battery applications, aluminum foil also functions as an electromagnetic shield. The appropriate thickness ensures that the aluminum foil effectively shields against external electromagnetic interference, protecting the internal circuitry of the battery from interference and improving the battery's operational stability and reliability. The 20 to 40 micrometer aluminum foil thickness offers a good balance between production cost and performance. Excessively thick aluminum foil can increase costs, while excessively thin foil may fail to provide sufficient protection. Therefore, this thickness range ensures that the performance requirements of the aluminum-plastic film are met while controlling costs. This thickness range of aluminum foil offers good processability and can be well laminated with polypropylene film and composite nylon layers. It ensures the overall structural consistency of the aluminum-plastic film during co-molding, guaranteeing the quality and performance stability of the final product. Thus, selecting an aluminum foil thickness of 20 to 40 micrometers provides optimized performance in terms of isolation properties, mechanical strength, thermal conductivity, electromagnetic shielding, and cost-effectiveness, thereby improving the overall performance of aluminum-plastic film in lithium batteries.

[0076] In conjunction with the first aspect, in some embodiments of the present invention, the thickness of the aluminum foil is any value of 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, or a range formed by any two of these values.

[0077] In conjunction with the first aspect, in some embodiments of the present invention, the thickness of the composite nylon layer is 20 micrometers to 40 micrometers.

[0078] Within this thickness range, the composite nylon layer can effectively integrate with the nano-metal-doped structure, improving overall thermal conductivity. Although nylon itself has a low thermal conductivity, this thickness range ensures that the nano-metals effectively enhance the material's thermal conductivity, helping to rapidly dissipate heat generated within the battery cell. Specifically, a thickness of 20 to 40 micrometers provides sufficient mechanical strength and durability, preventing the composite nylon layer from easily deforming or being damaged during battery operation. This strength is crucial for protecting internal battery components from damage caused by mechanical stress. The moderate thickness also helps the composite nylon layer maintain stability at high temperatures, preventing performance degradation due to thermal expansion or contraction. This effectively improves the thermal stability of the aluminum-plastic film under extreme operating conditions. A composite nylon layer thickness between 20 and 40 micrometers provides moderate flexibility, allowing it to better adapt to different shapes and sizes during battery packaging and application while maintaining good composite performance. This thickness range effectively balances heat conduction and dissipation, enhancing the thermal management capabilities of the entire battery system. By using an appropriate thickness, heat dissipation efficiency can be improved while maintaining thermal conductivity, thereby delaying the rapid rise in internal battery temperature. Choosing a thickness of 20 to 40 micrometers achieves a good balance between performance and cost. Thicker composite nylon layers may incur additional costs, while thinner layers may not provide sufficient protection and thermal conductivity. This thickness range ensures high performance while controlling production costs. Composite nylon layers of this thickness can better adapt to various molding processes and composite material processing requirements during manufacturing, ensuring the quality and consistency of the final product. Therefore, a composite nylon layer thickness of 20 to 40 micrometers offers comprehensive advantages in optimizing thermal conductivity, enhancing mechanical strength, maintaining thermal stability, providing flexibility, improving thermal management, controlling costs, and increasing processing adaptability, thereby enhancing the application effect of aluminum-plastic films in lithium batteries.

[0079] In conjunction with the first aspect, in some embodiments of the present invention, the thickness of the composite nylon layer is any value of 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, or a range formed by any two of these values.

[0080] In conjunction with the first aspect, in some embodiments of the present invention, a polyurethane adhesive layer is provided between the polypropylene film and the aluminum foil.

[0081] Polyurethane, as an excellent adhesive material, provides a strong bond, firmly connecting the polypropylene film and aluminum foil. This strong bond prevents the aluminum foil from peeling off during use, ensuring the overall structural stability and durability of the aluminum-plastic film.

[0082] Furthermore, the polyurethane adhesive layer possesses excellent sealing properties, helping to prevent moisture and gas penetration and enhancing the barrier properties of the membrane. This is crucial for protecting the chemicals and electrolyte inside the lithium battery, preventing environmental factors from affecting battery performance. Polyurethane exhibits good resistance to various chemicals, resisting the erosion of electrolytes and other chemicals, thereby extending the service life of the aluminum-plastic film and ensuring its long-term stability within the battery. The polyurethane adhesive layer provides additional flexibility, making the entire aluminum-plastic film more adaptable during use. It can effectively absorb and disperse stress, reducing damage caused by external impacts or vibrations. Polyurethane has good thermal stability, maintaining its adhesive properties and structural stability at high temperatures. This is particularly important for the high-temperature conditions in lithium battery thermal abuse testing, ensuring the membrane continues to function effectively under extreme conditions. Using a polyurethane adhesive layer simplifies the production process, making the lamination of polypropylene film and aluminum foil more efficient. The adhesive properties of polyurethane can achieve high bonding quality in conventional production processes, thereby improving production efficiency and product consistency. Through the design of the polyurethane adhesive layer, the overall durability of the aluminum-plastic film is significantly improved. It can resist long-term mechanical stress and environmental factors, reduce the aging and degradation of the film, and thus extend the service life of the product.

[0083] In terms of thermal management, the polyurethane adhesive layer effectively alleviates the stress caused by thermal expansion and contraction, helps maintain the structural integrity of the film, and assists in improving the battery's heat dissipation performance, especially important in high-temperature testing. Therefore, the use of the polyurethane adhesive layer between the polypropylene film and aluminum foil provides enhanced bond strength, improved sealing performance, excellent chemical resistance and thermal stability, as well as improved film flexibility, durability, and manufacturing efficiency. These advantages enable aluminum-plastic films to better protect internal materials and enhance overall performance in lithium battery applications.

[0084] In conjunction with the first aspect, in some embodiments of the present invention, the thickness of the polyurethane adhesive layer is 1 micrometer to 3 micrometers.

[0085] The polyurethane adhesive layer, with a thickness ranging from 1 to 3 micrometers, provides effective adhesive strength. This thin layer ensures a strong bond between the polypropylene film and the aluminum foil, preventing peeling or delamination during battery use due to mechanical stress or temperature changes. It maintains high adhesive strength while minimizing the space occupied within the battery. The 1- to 3-micrometer thick polyurethane layer also provides excellent sealing properties, preventing the penetration of moisture, gases, and other external substances that could affect battery performance. This thin layer effectively protects the battery's internal chemicals and electrolyte, avoiding negative impacts from the external environment and improving the battery's overall durability and stability. The thin polyurethane adhesive layer exhibits good thermal stability, maintaining stable adhesive performance within the operating temperature range without significantly affecting the film's thermal conductivity. This allows it to effectively assist in thermal management under high temperature or high heat load conditions without negatively impacting the battery's heat dissipation performance. Understandably, a thinner polyurethane adhesive layer reduces the amount of raw materials used, thereby reducing production costs. Due to its thinness, the production and processing costs of this adhesive layer are lower, improving economic efficiency while maintaining performance. The thin polyurethane adhesive layer provides flexibility, making the film more adaptable in applications. This flexibility helps the aluminum-plastic film better adapt to the needs of batteries of different shapes and sizes during production and use, reducing damage caused by mechanical stress. The thin polyurethane adhesive layer improves processing efficiency during manufacturing. Thinner layers are easier to coat and dry evenly, thus accelerating production and improving the overall efficiency of the production line. Furthermore, a polyurethane adhesive layer thickness between 1 and 3 micrometers can improve the overall adhesion and protective capabilities of the film without significantly increasing the film thickness. This configuration ensures the comprehensive performance of the aluminum-plastic film in practical applications, including mechanical strength, sealing, and thermal stability. The thin polyurethane adhesive layer helps improve the uniformity of the aluminum-plastic film. It avoids the uneven thickness problems that thicker layers may cause, thus ensuring the overall consistency and stability of the film, thereby improving product quality and reliability. The thinner polyurethane adhesive layer maintains the flexibility of the film, adapting to different application requirements. During battery encapsulation, it can better adapt to various shapes and sizes, ensuring that the film tightly encapsulates the battery.

[0086] Therefore, a polyurethane adhesive layer with a thickness of 1 to 3 micrometers can bring beneficial effects in terms of adhesion performance, sealing performance, thermal management, production cost, flexibility, processing efficiency and film uniformity, thereby improving the overall performance and economic benefits of aluminum-plastic film in lithium battery applications.

[0087] In conjunction with the first aspect, in some embodiments of the present invention, the thickness of the polyurethane adhesive layer is any value of 1 micrometer, 1.5 micrometer, 2 micrometer, 2.5 micrometer, 3 micrometer, or a range formed by any combination of both.

[0088] In conjunction with the first aspect, in some embodiments of the present invention, a polyethylene naphthalate adhesive layer is provided between the aluminum foil and the composite nylon layer.

[0089] The polyethylene naphthalate (PEG) adhesive layer provides strong and durable bond strength, ensuring a secure connection between the aluminum foil and the composite nylon layer. This high-strength bond helps improve the overall structural stability of the film, preventing delamination or peeling due to mechanical stress or long-term use. Furthermore, the PEG adhesive layer exhibits good thermal stability, maintaining its performance at high temperatures. As an adhesive layer, it can withstand the thermal loads of the battery under high-temperature operating conditions, resisting degradation or loss of adhesive properties, thus maintaining an effective bond between the aluminum foil and the composite nylon layer.

[0090] The polyethylene naphthalate (PEG) adhesive layer also possesses excellent airtightness and moisture resistance, effectively preventing the penetration of water vapor and gases, and protecting the internal chemicals of the battery from external environmental influences. This airtightness helps extend battery life and improve its overall performance and stability. The high toughness and flexibility of the PEG adhesive layer allow it to adapt to the expansion and contraction of the film, especially during battery thermal expansion and cooling. The flexible PEG adhesive layer can alleviate mechanical stress caused by temperature changes, thereby improving the durability and reliability of the film. The PEG adhesive layer is easy to process and coat, maintaining uniform thickness and consistent performance during film manufacturing. This excellent processability allows the PEG adhesive layer to be produced with stable quality and improves production efficiency. When the aluminum foil layer is combined with the PEG adhesive layer, the electromagnetic shielding capability of the film can be further enhanced. The polyethylene naphthalate (PEG) adhesive layer helps improve the shielding effect of the aluminum foil, preventing external electromagnetic interference from affecting the internal electronic components of the battery. The addition of the PEG adhesive layer optimizes the overall performance of the aluminum-plastic film, combining the excellent thermal conductivity of the aluminum foil with the mechanical strength and heat dissipation capacity of the composite nylon layer, thereby improving the overall performance of the film in lithium batteries. In summary, the PEG adhesive layer provides excellent adhesive strength, thermal stability, airtightness, flexibility, and processability between the aluminum foil and the composite nylon layer, while enhancing electromagnetic shielding and chemical resistance, thus significantly improving the overall performance and reliability of the aluminum-plastic film in lithium batteries.

[0091] In conjunction with the first aspect, in some embodiments of the present invention, the thickness of the polyethylene naphthalate adhesive layer is 1 micrometer to 3 micrometers.

[0092] In conjunction with the first aspect, in some embodiments of the present invention, the thickness of the polyethylene naphthalate adhesive layer is any value of 1 micrometer, 1.5 micrometer, 2 micrometer, 2.5 micrometer, 3 micrometer, or a range formed by any combination of both.

[0093] In conjunction with the first aspect, in some embodiments of the present invention, the nanometal includes nanosilver or nanocopper.

[0094] Both nano-silver and nano-copper possess excellent thermal conductivity. Adding these nano-metals to the composite nylon layer significantly improves its thermal conductivity. Nano-silver boasts a thermal conductivity of approximately 429 W / (m·K), while nano-copper reaches approximately 385 W / (m·K), greatly enhancing the overall thermal conductivity of the aluminum-plastic film and thus more effectively transferring heat generated inside the battery cell to the film surface. Furthermore, by improving the thermal conductivity of the composite nylon layer, the nano-metals enhance the film's heat dissipation performance. When chemical heat is generated inside the battery due to high temperatures, the nano-metals help accelerate heat conduction and dispersion, preventing heat concentration and reducing the risk of cell failure due to overheating. Further, the addition of nano-metals helps reduce the risk of thermal failure due to temperature rise. By increasing the heat dissipation rate, the temperature rise of the battery cell can be more effectively controlled, preventing material decomposition, fire, or explosion caused by high temperatures. It is understandable that the distribution of nano-metals not only improves thermal conductivity but may also have a positive impact on the structural stability of the composite nylon layer. Uniformly distributed nanomaterials can enhance the mechanical strength of the film, improve its stability under high temperature conditions, and prevent interlayer separation or peeling.

[0095] Improving thermal conductivity and heat dissipation performance can significantly enhance the performance of battery cells in thermal shock testing, i.e., increase the thermal chamber pass rate. This is particularly important for high-voltage silicon-carbon anode lithium batteries, as their stability at high temperatures is crucial for safety. The use of highly thermally conductive nano-metals helps optimize overall battery performance and extend battery life. Better heat dissipation ensures battery stability during long-term use and reduces performance degradation caused by overheating. The high thermal conductivity of nano-silver and nano-copper can reduce the overall thermal management requirements of the film layer, improving the adaptability and efficiency of aluminum-plastic films in battery manufacturing processes, thereby increasing production efficiency and product quality. By optimizing the heat conduction path and improving heat dissipation efficiency, nano-metals can effectively reduce thermal failure problems caused by localized overheating, thereby improving battery safety and reliability. Therefore, introducing nano-silver or nano-copper into composite nylon layers can significantly improve the thermal conductivity and heat dissipation performance of aluminum-plastic films, reduce the risk of battery failure due to high temperatures, optimize overall battery performance, and improve performance in thermal shock testing.

[0096] The thermal conductivity of silver is 429 W / (m·K), that of copper is generally 385 W / (m·K), and that of aluminum is 237 W / (m·K).

[0097] The thermal conductivity of the adhesive layer is generally less than 1 W / (m·K).

[0098] In conjunction with the first aspect, in some embodiments of the present invention, the morphology of the nanometal includes nanosheets or nanoparticles.

[0099] Nanosheet-like metallic materials have a large specific surface area, providing more heat conduction channels. Due to their flat shape, they are conducive to forming a continuous heat conduction network in the composite nylon layer, thereby effectively improving the overall thermal conductivity.

[0100] Nanosheets possess strong thermal conductivity, enabling rapid heat transfer and reducing localized high temperatures. They improve the uniform distribution of heat within the film, preventing overheating caused by concentrated heat. By enhancing the thermal conductivity of the film, nanosheets effectively reduce the rapid rise in internal battery temperature. This enhances the film's thermal stability and reduces the risk of battery failure due to high temperatures. The increased number of nanosheets creates a larger effective thermal conductivity area, allowing heat to be conducted more efficiently from the inside of the cell to the outside, thus improving heat dissipation efficiency. Due to their excellent thermal conductivity, nanosheets can significantly improve the cell's performance in thermal shock tests, reducing failures caused by overheating. Furthermore, the flat structure of nanosheets effectively enhances the structural stability of the composite nylon layer, reducing material degradation or delamination under high-temperature environments.

[0101] While the thermal conductivity of a single particle may not be as high as that of a nanosheet, particle dispersion enhances the thermal conductivity of the composite layer by providing multiple thermal conduction paths. Particles effectively fill the voids in the composite nylon layer, reducing thermal resistance. By forming a complex thermally conductive network within the composite nylon layer, nanoparticles effectively improve thermal diffusivity, facilitating faster heat transfer to the outside of the membrane. The nanoparticles dispersed in the composite nylon layer not only improve thermal conductivity but also increase the mechanical strength of the membrane, making it less prone to deformation or failure at high temperatures. Although the surface area of ​​a single particle is small, their high-density distribution enhances the overall heat dissipation capacity of the membrane, effectively expanding the heat dissipation area. The uniform distribution of particles effectively enhances the thermal management capabilities of the membrane, resulting in a smoother thermal shock response of the battery cell during testing and improved thermal chamber pass rate. The nanoparticles distributed within the composite nylon layer improve the overall structural strength of the membrane, enhancing its resilience under extreme temperature conditions.

[0102] Whether it's nanosheets or nanoparticles, optimizing thermal conductivity and structural stability can improve the overall performance of batteries, including enhancing battery safety, extending lifespan, and reducing performance degradation caused by high temperatures.

[0103] In conjunction with the first aspect, in some embodiments of the present invention, the method for preparing the aluminum-plastic film includes the steps of co-molding nano-metals and nylon particles to obtain a composite nylon layer, and then compounding a polypropylene film, an aluminum foil, and the composite nylon layer.

[0104] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0105] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0106] Unless otherwise specified, "room temperature" in this invention means 25℃±5℃.

[0107] Unless otherwise specified, "about" in this invention means that the allowable error is within ±2%.

[0108] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0109] Example 1

[0110] First, an aluminum-plastic film was prepared, with the structure referenced. Figure 1 As shown. Specifically, it consists of a polypropylene film 100, an aluminum foil 300, and a composite nylon layer 500 arranged sequentially. The composite nylon layer 500 contains distributed nano-metal 510, and its outer surface has several strip-shaped protrusions. Wherein:

[0111] The thickness of polypropylene film 100 is 55 micrometers.

[0112] The thickness of aluminum foil 300 is 30 micrometers.

[0113] The thickness of the composite nylon layer 500 is 30 micrometers.

[0114] A polyurethane adhesive layer 200 is provided between the polypropylene film 100 and the aluminum foil 300, and the thickness of the polyurethane adhesive layer 200 is 2 micrometers.

[0115] A polyethylene naphthalate adhesive layer 400 is provided between the aluminum foil 300 and the composite nylon layer 500. The thickness of the polyethylene naphthalate adhesive layer 400 is 2 micrometers.

[0116] The nano-metal is silver nanoparticles with a particle size of 15 micrometers.

[0117] The width of the raised strip is 0.2 mm.

[0118] The height of the strip-shaped protrusions is 6 micrometers.

[0119] refer to Figure 2 As shown, the strip-shaped protrusions have a sinusoidal waveform and an arched cross-section.

[0120] The preparation method of aluminum-plastic film is as follows: nano-metal and nylon particles are co-molded to obtain a composite nylon layer, and then polypropylene film, aluminum foil and composite nylon layer are compounded.

[0121] The content of silver nanoparticles in the composite nylon layer is 1 wt%.

[0122] The process parameters for co-molding include:

[0123] The temperature of the molten nano-metal particles with nylon is 240℃~260℃;

[0124] The injection pressure is between 50-150 MPa;

[0125] Maintain pressure for 5 to 30 seconds and cool down for 10 to 60 seconds.

[0126] Furthermore, using the aluminum-plastic film prepared above, a lithium-ion battery was prepared, including a battery cell and an aluminum-plastic film wrapping the battery cell, wherein the battery cell includes a positive electrode, a separator, a negative electrode, and an aluminum-plastic film.

[0127] (1) Preparation of positive electrode sheet

[0128] The positive electrode material lithium cobalt oxide, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) were thoroughly mixed in an N-methylpyrrolidone solvent system at a mass ratio of 97.9:1.3:0.8. The mixture was then coated onto aluminum foil, dried, rolled, and slit to obtain the positive electrode sheet.

[0129] (2) Preparation of negative electrode sheet

[0130] The negative electrode material (mixed with 10% silicon carbon), conductive agent acetylene black, conductive agent single-arm carbon nanotube (SWCNT), binder styrene-butadiene rubber (SBR), lithium-ionized polyacrylic acid (PAALI), and thickener sodium carboxymethyl cellulose (CMC) are thoroughly mixed in a deionized water solvent system at a mass ratio of 96:0.5:0.05:1:1.95:0.5. The mixture is then coated onto copper foil, dried, rolled, and slit to obtain the negative electrode sheet.

[0131] (3) Preparation of the separating membrane

[0132] A porous polyethylene (PE) polymer film is used as the base layer of the isolation membrane, and an oil-based ceramic (PVDF and alumina ceramic) surface layer is provided on the surface of the base layer.

[0133] (4) Preparation of electrolyte

[0134] A solution prepared by mixing lithium salt LiPF6 with a non-aqueous organic solvent (ethylene carbonate (EC): diethyl carbonate (DEC): propylene carbonate (PC): propyl propionate (PP)) in a mass ratio of 25:10:15:50, with a mass ratio of 8:92, is used as the electrolyte for lithium batteries.

[0135] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes for safety isolation. The electrode assembly is then wound up to form the electrode assembly. The electrode assembly is placed in a perforated aluminum-plastic film, electrolyte is injected, and the assembly is sealed (because metal is doped into the nylon layer of the aluminum-plastic film, the sealing process involves melting and sealing a polypropylene film, which has no impact on the sealing process), thus obtaining a lithium battery.

[0136] In Example 1, the nano-silver particles had a particle size of 35 nanometers and were added to the composite nylon layer at a rate of 1 wt%. The membrane used had a shrinkage rate of 0.9%.

[0137] Example 2

[0138] The difference from Example 1 is that the size of the silver nanoparticles is 55 nanometers.

[0139] Example 3

[0140] The difference from Example 1 is that the nano-silver particles have a particle size of 75 nanometers.

[0141] Example 4

[0142] The difference from Example 1 is that the content of silver nanoparticles in the composite nylon layer is 3 wt%.

[0143] Example 5

[0144] The difference from Example 1 is that the particle size of the silver nanoparticles is 55 nanometers. The content of silver nanoparticles in the composite nylon layer is 3 wt%.

[0145] Example 6

[0146] The difference from Example 1 is that the silver nanoparticles have a particle size of 75 nanometers. The content of silver nanoparticles in the composite nylon layer is 3 wt%.

[0147] Example 7

[0148] The difference from Example 1 is that the content of silver nanoparticles in the composite nylon layer is 5 wt%.

[0149] Example 8

[0150] The difference from Example 1 is that the silver nanoparticles have a particle size of 55 nanometers. The content of silver nanoparticles in the composite nylon layer is 5 wt%.

[0151] Example 9

[0152] The difference from Example 1 is that the silver nanoparticles have a particle size of 75 nanometers. The content of silver nanoparticles in the composite nylon layer is 5 wt%.

[0153] Example 10

[0154] The difference from Example 1 is that the nano-metal is copper nanoparticles.

[0155] Example 11

[0156] The difference from Example 1 is that the nanometal is copper nanoparticles with a particle size of 55 nanometers. The content of copper nanoparticles in the composite nylon layer is 1 wt%.

[0157] Example 12

[0158] The difference from Example 1 is that the nanometal is copper nanoparticles with a particle size of 75 nanometers. The content of copper nanoparticles in the composite nylon layer is 1 wt%.

[0159] Example 13

[0160] The difference from Example 1 is that the nano-metal is copper nanoparticles, and the content of silver nanoparticles in the composite nylon layer is 3wt%.

[0161] Example 14

[0162] The difference from Example 1 is that the nanometal is copper nanoparticles with a particle size of 55 nanometers. The content of copper nanoparticles in the composite nylon layer is 3 wt%.

[0163] Example 15

[0164] The difference from Example 1 is that the nanometal is copper nanoparticles with a particle size of 75 nanometers. The content of copper nanoparticles in the composite nylon layer is 3 wt%.

[0165] Example 16

[0166] The difference from Example 1 is that the nano-metal is copper nanoparticles, and the content of copper nanoparticles in the composite nylon layer is 5 wt%.

[0167] Example 17

[0168] The difference from Example 1 is that the nanometal is copper nanoparticles with a particle size of 55 nanometers. The content of copper nanoparticles in the composite nylon layer is 5 wt%.

[0169] Example 18

[0170] The difference from Example 1 is that the nanometal is copper nanoparticles with a particle size of 75 nanometers. The content of copper nanoparticles in the composite nylon layer is 5 wt%.

[0171] Example 19

[0172] The difference from Example 1 is that the silver nanoparticles have a particle size of 55 nanometers. (Reference) Figure 3 As shown, the strip-shaped protrusions are parallel straight lines, and the spacing between the strip-shaped protrusions is 1 mm.

[0173] Example 20

[0174] The difference from Example 1 is that the diaphragm used has a shrinkage rate of 1.45%.

[0175] Example 21

[0176] The difference from Example 1 is that the particle size of the silver nanoparticles is 55 nanometers, the shrinkage rate of the diaphragm used is 4.5%, and the content of silver nanoparticles in the composite nylon layer is 5 wt%.

[0177] Comparative Example 1

[0178] The difference from Example 1 is that no nano-metals were added.

[0179] Comparative Example 2

[0180] The difference from Example 1 is that no nano-metals were added, and the strip-shaped protrusions are parallel straight lines.

[0181] Comparative Example 3

[0182] The difference from Example 1 is that no nano-metals were added, and the diaphragm used had a shrinkage rate of 1.45%.

[0183] Comparative Example 4

[0184] The difference from Example 1 is that no nano-metals were added, and the diaphragm used had a shrinkage rate of 4.5%.

[0185] Comparative Example 5

[0186] The difference from Example 1 is that the diaphragm used has a shrinkage rate of 4.5%.

[0187] Comparative Example 6

[0188] The difference from Example 1 is that the diaphragm used has a shrinkage rate of 0.5%, and the content of nano-silver particles in the composite nylon layer is 5 wt%.

[0189] The design parameters for the embodiments and comparative examples are shown in Table 1.

[0190] Table 1

[0191]

[0192]

[0193] Security performance test

[0194] The lithium-ion battery thermal abuse performance of the batteries prepared in Examples 1 to 21 and Comparative Examples 1 to 6 were tested.

[0195] The lithium-ion batteries were placed in a 25°C constant temperature chamber and left to stand for 30 minutes to allow them to reach a constant temperature. The batteries were then charged at a constant current of 0.5C to a voltage of 4.53V, followed by constant voltage charging at 4.53V to a current of 0.05C. After resting for 60 minutes, the cells were placed in an oven at X°C (X = 124, 126, 128, 130, 132, 134, 136, 138, 140°C). The oven temperature was increased to X°C at a rate of 5 ± 2°C / min and maintained for 30 minutes. During this process, the cell surface temperature, ambient temperature, and voltage were monitored. Specific test data are shown in Table 2.

[0196] Table 2

[0197]

[0198]

[0199] As can be seen from Table 2, the batteries in the examples experienced significantly higher temperatures in the hot chamber than the comparative examples, especially the batteries in Examples 8 and 9, which remained stable at 140°C. This indicates that adding nano-metals and using specific corrugated shapes (such as sine waves) effectively improved the thermal stability of the batteries.

[0200] The examples of nano-silver generally outperformed nano-copper, especially at higher mass fractions (e.g., 3% and 5%), where the batteries passed tests at higher temperatures. For example, in Examples 8 and 9, nano-silver passed the test at 140°C at a 5% mass fraction, while nano-copper passed the test at a slightly lower temperature under the same conditions.

[0201] The particle size of nanometals also has a significant impact on performance. Larger particle sizes (e.g., 75 nm) are generally associated with higher thermal stability, as shown in Examples 3, 6, 9, 12, 15, and 18, which exhibit higher pass temperatures.

[0202] Regarding the effect of corrugation shape, embodiments with sine wave designs are generally superior to those with straight corrugation shapes (such as Embodiments 2 and 19, Comparative Examples 1 and 2). This suggests that sine wave shapes may have a better effect on heat dissipation.

[0203] Comparative Examples 1 and 2 performed the worst in the test, failing at 126°C and 124°C respectively, which was significantly lower than the vast majority of examples, demonstrating the effectiveness of doping with nano-metals and design optimization (such as corrugated shape) in improving thermal stability.

[0204] Compared with Comparative Example 3, Example 20 showed a 2°C increase in the temperature chamber after the 1.45% high-yield membrane was doped with metal.

[0205] Compared with Comparative Example 4, Example 21 showed that after the 4.5% high-yield membrane was doped with metal, the hot box still had a 6°C increase.

[0206] Comparing Comparative Example 1 and Comparative Example 2, it can be seen that the sine wave has better performance than the straight wave in the heat box.

[0207] Comparing column 5 with implementation column 21, it can be seen that the performance of the hot box deteriorates when Y / Z is outside the range.

[0208] Comparing column 6 with implementation column 7, it can be seen that when Y / Z is not within the range, although the hot box performance is better, the cost is higher due to the use of a diaphragm with a lower shrinkage rate.

[0209] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A lithium-ion battery, characterized in that, The battery includes a battery cell and an aluminum-plastic film encapsulating the battery cell. The battery cell includes a positive electrode, a separator, a negative electrode, and an electrolyte. The shrinkage rate of the separator is Y%. The aluminum-plastic film includes a polypropylene film, an aluminum foil, and a composite nylon layer arranged sequentially. Nano-metals are distributed in the composite nylon layer. The particle size of the nano-metals is 35nm to 75nm. The amount of nano-metals added to the composite nylon layer is Zwt%. Y and Z satisfy the relationship 0.18≤Y / Z≤1.

45.

2. The lithium-ion battery according to claim 1, characterized in that, The isolation membrane comprises a base layer and a surface layer arranged sequentially; and / or, the base layer is made of PP or PE; and / or, the surface layer is made of PVDF and alumina ceramic.

3. The lithium-ion battery according to claim 1, characterized in that, The outer surface of the composite nylon layer is provided with a plurality of strip-shaped protrusions; and / or, the line width of the strip-shaped protrusions is 0.1 mm to 0.3 mm; and / or, the height of the strip-shaped protrusions is 4 micrometers to 8 micrometers.

4. The lithium-ion battery according to claim 3, characterized in that, The strip-shaped protrusions are parallel to each other; and / or the spacing between the strip-shaped protrusions is 0.5 mm to 2 mm.

5. The lithium-ion battery according to claim 3, characterized in that, The strip-shaped protrusion has a sinusoidal waveform; and / or, the cross-section of the strip-shaped protrusion includes at least one of arch, triangle and rectangle.

6. The lithium-ion battery according to any one of claims 1 to 5, characterized in that, The thickness of the polypropylene film is 30 micrometers to 80 micrometers; and / or the thickness of the aluminum foil is 20 micrometers to 40 micrometers; and / or the thickness of the composite nylon layer is 20 micrometers to 40 micrometers.

7. The lithium-ion battery according to any one of claims 1 to 5, characterized in that, A polyurethane adhesive layer is provided between the polypropylene film and the aluminum foil; and / or, the thickness of the polyurethane adhesive layer is 1 micrometer to 3 micrometers.

8. The lithium-ion battery according to any one of claims 1 to 5, characterized in that, A polyethylene naphthalate adhesive layer is provided between the aluminum foil and the composite nylon layer; and / or, the thickness of the polyethylene naphthalate adhesive layer is 1 micrometer to 3 micrometers.

9. The lithium-ion battery according to any one of claims 1 to 5, characterized in that, The nanometal includes nanosilver or nanocopper; and / or, the morphology of the nanometal includes nanosheets or nanoparticles.

10. The lithium-ion battery according to any one of claims 1 to 5, characterized in that, The method for preparing the aluminum-plastic film includes the steps of co-molding the nano-metal and nylon particles to obtain a composite nylon layer, and then combining the polypropylene film, aluminum foil and the composite nylon layer.

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