Flame-retardant composition, flame-retardant layer and new energy automobile power battery comprising flame-retardant layer

Abstract

The invention relates to a flame-retardant composition, a flame-retardant layer and a new energy automobile power battery comprising the flame-retardant layer. The flame-retardant composition comprises the following components in percentage by weight: 50-68% of matrix resin which is a mixture of polycarbonate and polyphenyl ether in a weight ratio of (1: 1)-(3: 1); the composite flame retardant comprises a phosphate flame retardant, a cyanamide flame retardant and an inorganic flame retardant according to the weight ratio of 1: (0.5-0.8): (2-2.5), and the inorganic flame retardant is selected from one or more of aluminum hydroxide, antimony trioxide, magnesium hydroxide and zinc borate; 10-20% by weight of a thermally conductive agent; 5 to 10 wt% of a silane coupling agent; and 1-3 wt% of a lubricant. A flame-retardant layer formed by the flame-retardant composition is arranged between a power battery module and an aluminum shell of the new energy automobile power battery, has good flame retardance, heat conduction and mechanical properties, and can meet the use requirements of the new energy automobile power battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy vehicles, and specifically relates to a flame retardant composition for a new energy vehicle power battery, a flame retardant layer formed by the composition, and a new energy vehicle power battery comprising the flame retardant layer. Background Art

[0002] Amidst the growing global energy crisis and environmental challenges, new energy vehicles (NEVs), with their energy-saving and environmentally friendly advantages, have become a key driver of the automotive industry's transformation and upgrading. As a core component of NEVs, the safety, reliability, and performance of power batteries directly impact their development and application. As the range requirements for NEVs continue to increase, the energy density of power batteries is also continuously increasing. This increases the risk of overheating and safety hazards during operation. Thermal runaway in a power battery can not only damage the vehicle but can also cause serious safety incidents such as fires and explosions, threatening the lives of passengers. Therefore, improving power battery safety has become a critical issue that needs to be addressed in the NEV sector.

[0003] Flame retardant technology is one of the important means to improve the safety of power batteries. At present, the commonly used power battery flame retardant materials on the market mainly include flame retardant plastics, flame retardant rubbers, flame retardant coatings, etc. However, these traditional flame retardant materials have many shortcomings in practical applications. For example, although some flame retardant plastics have good flame retardant properties, they have poor thermal conductivity and cannot dissipate the heat generated by the power battery in time, which easily leads to heat accumulation and further increases the risk of thermal runaway. On the other hand, some materials with good thermal conductivity have flame retardant properties that are difficult to meet the safety requirements of power batteries. In addition, the mechanical properties of traditional flame retardant materials often cannot meet the use requirements of power batteries well. When subjected to external forces such as vibration and impact, they are prone to cracking, deformation and other problems, affecting the overall performance and service life of the power battery.

[0004] In existing power battery structures, the heat-insulating flame-retardant layer between the battery module and the aluminum shell is an important component for ensuring the safety of the power battery. This flame-retardant layer not only needs to have excellent flame-retardant properties to prevent the spread of flames when the battery experiences thermal runaway, but also needs to have good thermal conductivity to conduct the heat generated by the battery in a timely manner and reduce the battery temperature. At the same time, the flame-retardant layer should also have high mechanical strength to withstand various external forces acting on the battery module during installation and use, thereby ensuring the stability of the battery structure. However, the market currently lacks a flame-retardant material that can simultaneously meet the requirements of flame retardancy, thermal conductivity, and mechanical properties for use as a flame-retardant layer between the power battery module and the aluminum shell.

[0005] Some existing flame-retardant compositions often enhance their flame retardancy by adding large amounts of flame retardants. However, this can lead to a decrease in the material's mechanical and processing properties, and also affect its thermal conductivity. For example, while inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide offer good flame retardancy, adding large amounts can make the material brittle and hard, significantly reducing its tensile and flexural strengths. Organic flame retardants such as phosphate esters, while less effective on the material's mechanical properties, have limited flame retardant effectiveness when used alone, necessitating their combination with other flame retardants, further increasing the complexity and cost of the formulation.

[0006] In terms of thermal conductivity, existing flame-retardant materials typically enhance their thermal conductivity by adding thermally conductive fillers such as graphene, aluminum powder, and carbon nanotubes. However, the amount and dispersion of these fillers significantly impact the thermal and mechanical properties of the material. Insufficient fillers can result in suboptimal thermal conductivity; excessive additions can lead to filler aggregation within the matrix resin, impacting the material's mechanical and processing properties. Furthermore, compatibility issues between the filler and the matrix resin can impact the overall performance of the material.

[0007] In terms of mechanical performance, power batteries are subject to a variety of external forces during use, such as vibration, impact, and temperature fluctuations. Therefore, the flame-retardant layer must possess high tensile strength, flexural strength, and toughness. Some existing flame-retardant materials, due to poor formulation design, fail to meet the mechanical performance requirements of power batteries. For example, the mechanical properties of some flame-retardant materials significantly degrade in high-temperature environments, making it impossible to ensure the structural stability of power batteries during long-term use.

[0008] In summary, existing flame-retardant materials used in new energy vehicle power batteries struggle to balance flame retardancy, thermal conductivity, and mechanical properties, failing to meet the safety and reliability requirements of new energy vehicles for power batteries. Therefore, there is an urgent need to develop a flame-retardant composition with excellent flame retardancy, thermal conductivity, and mechanical properties for use as the flame-retardant layer between power battery modules and aluminum housings. This will improve the safety and reliability of power batteries and promote the healthy development of the new energy vehicle industry. Summary of the Invention

[0009] The purpose of the present invention is to provide a flame retardant composition for new energy vehicle power batteries. The flame retardant layer formed by the flame retardant composition is arranged between the battery module and the aluminum shell of the new energy vehicle power battery. The flame retardant layer has good flame retardant properties, thermal conductivity and mechanical properties (tensile strength and bending strength) to solve the above-mentioned problems existing in the prior art.

[0010] Specifically, according to one aspect of the present invention, there is provided a flame retardant composition, the flame retardant composition comprising, based on the total weight thereof: 50-68 wt% of a base resin, wherein the base resin is a mixture of polycarbonate and polyphenylene ether in a weight ratio of 1:1-3:1; 15-28 wt % of a composite flame retardant, the composite flame retardant comprising a phosphate flame retardant, a cyanamide flame retardant, and an inorganic flame retardant in a weight ratio of 1:0.5-0.8:2-2.5, wherein the inorganic flame retardant is selected from one or more of the group consisting of aluminum hydroxide, antimony trioxide, magnesium hydroxide, and zinc borate; 10-20 wt% of a thermal conductor; 5-10 wt% of a silane coupling agent; and 1-3 wt% lubricant.

[0011] According to certain preferred embodiments of the present invention, the weight average molecular weight of the polycarbonate is in the range of 25,000-60,000 g / mol, preferably 30,000-40,000 g / mol, more preferably 30,000-35,000 g / mol.

[0012] According to certain preferred embodiments of the present invention, the polycarbonate is one or more selected from the group consisting of bisphenol A polycarbonate, bisphenol S polycarbonate, organosilicon-modified polycarbonate and polyester-modified polycarbonate.

[0013] According to certain preferred embodiments of the present invention, the polycarbonate is bisphenol A polycarbonate.

[0014] According to certain preferred embodiments of the present invention, the weight average molecular weight of the polyphenylene ether is in the range of 5,000-25,000 g / mol, preferably 10,000-25,000 g / mol, more preferably 15,000-23,000 g / mol.

[0015] According to certain preferred embodiments of the present invention, the phosphate flame retardant is one or more selected from the group consisting of triphenyl phosphate (TPP), tricresyl phosphate (TCP) and tri(2-ethylhexyl) phosphate (TEHP).

[0016] According to certain preferred embodiments of the present invention, the cyanamide flame retardant is one or more selected from the group consisting of melamine cyanurate (MCA), melamine and dicyandiamide.

[0017] According to certain preferred embodiments of the present invention, the silane coupling agent is one or more selected from the group consisting of vinyltriethoxysilane, γ-aminopropyltriethoxysilane, vinyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane.

[0018] According to certain preferred embodiments of the present invention, the composite flame retardant comprises triphenyl phosphate (TPP), melamine cyanurate (MCA), and aluminum hydroxide in a weight ratio of 1:0.6-0.65:2.3-2.5.

[0019] According to certain preferred embodiments of the present invention, the thermal conductor is selected from one or more of the group consisting of graphene, aluminum powder, nickel powder, carbon nanotubes and carbon fibers.

[0020] According to certain preferred embodiments of the present invention, the lubricant is selected from one or more of the group consisting of stearic acid, calcium stearate and paraffin.

[0021] According to certain preferred embodiments of the present invention, the flame retardant composition further comprises 1-3 wt % of an antioxidant based on the total weight of the flame retardant composition.

[0022] According to certain preferred embodiments of the present invention, the antioxidant is a mixture of a hindered phenol antioxidant and a phosphite antioxidant in a weight ratio of 1:1-2:1.

[0023] According to certain preferred embodiments of the present invention, the hindered phenol antioxidant is one or more selected from the group consisting of 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol and 2,4,6-tri-tert-butylphenol.

[0024] According to certain preferred embodiments of the present invention, the phosphite antioxidant is one or more selected from the group consisting of pentaerythritol diisodecyl diphosphite, triphenyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite and diphenyl isodecyl phosphite.

[0025] According to certain preferred embodiments of the present invention, the flame retardant composition further comprises a colorant.

[0026] According to certain preferred embodiments of the present invention, the flame retardant composition comprises 2 wt% or less of the colorant based on the total weight of the flame retardant composition.

[0027] According to another aspect of the present invention, a flame retardant layer is provided, comprising the flame retardant composition described above.

[0028] According to certain preferred embodiments of the present invention, the thickness of the flame retardant layer is in the range of 0.5 mm to 5 mm, preferably 1 mm to 3 mm.

[0029] According to another aspect of the present invention, a new energy vehicle power battery is provided, the new energy vehicle power battery comprising: Power battery module; an aluminum shell encapsulating the power battery module; and The flame retardant layer mentioned above is provided between the power battery module and the aluminum shell and is in contact with the same. DETAILED DESCRIPTION

[0030] It should be understood that those skilled in the art can conceive of other various embodiments and can modify them according to the teachings of this specification without departing from the scope or spirit of the present disclosure. Therefore, the following specific embodiments are not intended to be limiting.

[0031] Unless otherwise indicated, all numbers used in this specification to express feature sizes, quantities, and physical and chemical properties should be understood as being modified in all instances by the term "about." Therefore, unless otherwise indicated, the numerical parameters listed in the above description are approximate values, and those skilled in the art will be able to appropriately change these approximate values ​​to seek to obtain the desired properties using the teachings disclosed herein.

[0032] As mentioned above, existing flame-retardant materials for new energy vehicle power batteries have numerous shortcomings: materials with good flame retardancy have poor thermal conductivity, easily leading to heat accumulation; materials with good thermal conductivity lack flame retardancy; and materials with poor mechanical properties are prone to cracking and deformation under external forces. Furthermore, there is a conflict between the amount of flame retardant added and the material's performance. There is a lack of materials that can simultaneously meet the flame retardancy, thermal conductivity, and mechanical performance requirements for the flame-retardant layer between the battery module and the aluminum casing.

[0033] The present inventors discovered that using a specific weight ratio of polycarbonate and polyphenylene ether (1:1-3:1) as the matrix resin can fully utilize the impact resistance of polycarbonate and the heat resistance of polyphenylene ether, forming a stable skeleton with complementary properties, laying the foundation for the material's mechanical properties. Further research has shown that compounding phosphate flame retardants, cyanamide flame retardants, and inorganic flame retardants in a specific weight ratio (1:0.5-0.8:2-2.5) can improve flame retardant efficiency while reducing the total amount of additives through the synergistic effects of gas-phase flame retardancy and condensed-phase flame retardancy. Among them, the optimal effect is achieved when triphenyl phosphate (TPP), melamine cyanurate (MCA), and aluminum hydroxide are mixed in a ratio of 1:0.6-0.65:2.3-2.5. In addition, adding 10-20 wt% thermal conductor can build an efficient thermal conductive network, and 5-10 wt% silane coupling agent can improve the interfacial compatibility of each component, solving the problem of flame retardancy, thermal conductivity and mechanical properties being difficult to balance in traditional materials, so that the composition can meet the comprehensive performance requirements of the flame retardant layer of the power battery.

[0034] Based on the above, the present invention specifically relates to a flame-retardant composition for use in new energy vehicle power batteries, a flame-retardant layer formed from the composition, and a new energy vehicle power battery containing the flame-retardant layer. The present invention aims to address the existing problem of flame-retardant materials for new energy vehicle power batteries, which struggle to simultaneously meet the requirements for flame retardancy, thermal conductivity, and mechanical properties. The present invention provides a flame-retardant composition with excellent overall performance, a flame-retardant layer prepared from the composition, and a new energy vehicle power battery containing the flame-retardant layer.

[0035] Specifically, according to one aspect of the present invention, there is provided a flame retardant composition, the flame retardant composition comprising, based on the total weight thereof: 50-68 wt% of a base resin, wherein the base resin is a mixture of polycarbonate and polyphenylene ether in a weight ratio of 1:1-3:1; 15-28 wt % of a composite flame retardant, the composite flame retardant comprising a phosphate flame retardant, a cyanamide flame retardant, and an inorganic flame retardant in a weight ratio of 1:0.5-0.8:2-2.5, wherein the inorganic flame retardant is selected from one or more of the group consisting of aluminum hydroxide, antimony trioxide, magnesium hydroxide, and zinc borate; 10-20 wt% of a thermal conductor; 5-10 wt% of a silane coupling agent; and 1-3 wt% lubricant.

[0036] According to the technical solution of the present invention, the flame retardant composition comprises 50-68 wt % of a base resin, and the base resin is a mixture of polycarbonate and polyphenylene ether in a weight ratio of 1:1-3:1.

[0037] Polycarbonate (PC) is an engineering plastic with excellent impact resistance, heat resistance, and light transmittance. Its molecular chain contains carbonate groups, which give the material good mechanical properties and flame retardant potential. Polyphenylene ether (PPO) has excellent heat resistance, chemical corrosion resistance, and electrical insulation, but its processing performance is relatively poor. The present invention, by mixing polycarbonate and polyphenylene ether in a specific ratio, can fully utilize the synergistic effect of the two. Polycarbonate improves the processing performance and impact resistance of polyphenylene ether, while polyphenylene ether also improves the heat resistance and dimensional stability of the material, thereby providing a good mechanical performance foundation for the flame retardant composition.

[0038] Specifically, a weight ratio of polycarbonate to polyphenylene ether of 1:1 to 3:1 achieves the best performance balance. Too high a polycarbonate ratio may reduce the material's heat resistance, while too high a polyphenylene ether ratio increases processing difficulty and reduces impact resistance.

[0039] In a preferred embodiment of the present invention, the weight-average molecular weight of the polycarbonate is within the range of 25,000-60,000 g / mol, preferably 30,000-40,000 g / mol, and more preferably 30,000-35,000 g / mol. The molecular weight of a polycarbonate significantly impacts its performance. A high molecular weight can lead to poor melt flow, hindering processing; a low molecular weight can degrade the material's mechanical properties. Selecting a polycarbonate within this molecular weight range ensures both good mechanical properties and excellent processing properties.

[0040] Preferably, the polycarbonate can be selected from one or more of the group consisting of bisphenol A polycarbonate, bisphenol S polycarbonate, organosilicon-modified polycarbonate, and polyester-modified polycarbonate, with bisphenol A polycarbonate being preferred. Bisphenol A polycarbonate is a widely used polycarbonate, offering excellent overall performance and relatively low cost, and can meet the performance requirements of the base resin of the present invention.

[0041] Preferably, the weight-average molecular weight of the polyphenylene ether is in the range of 5,000-25,000 g / mol, more preferably 10,000-25,000 g / mol, and more preferably 15,000-23,000 g / mol. The molecular weight of the polyphenylene ether also affects the material's properties. An appropriate molecular weight ensures good heat resistance and mechanical properties, while facilitating mixing and processing with polycarbonate.

[0042] According to the technical solution of the present invention, the flame-retardant composition comprises 15-28% by weight of a composite flame retardant, wherein the composite flame retardant comprises a phosphate flame retardant, a cyanamide flame retardant, and an inorganic flame retardant in a weight ratio of 1:0.5-0.8:2-2.5, wherein the inorganic flame retardant is selected from one or more of the group consisting of aluminum hydroxide, antimony trioxide, magnesium hydroxide, and zinc borate. The present invention employs a composite flame retardant system, which, through the synergistic effect of different types of flame retardants, significantly improves the flame retardant properties of the material while reducing the total amount of flame retardant added, thereby avoiding the adverse effects of large amounts of a single flame retardant on other material properties.

[0043] Specifically, the flame retardant mechanism of phosphate flame retardants is mainly to decompose at high temperatures to produce substances such as phosphoric acid, which can suppress the combustion reaction of combustibles and form a carbon layer on the material surface, preventing the transfer of heat and oxygen. In the present invention, the phosphate flame retardant can be selected from one or more of the group consisting of triphenyl phosphate (TPP), tricresyl phosphate (TCP) and tri(2-ethylhexyl) phosphate (TEHP). These phosphate flame retardants have good flame retardant effects and compatibility with the matrix resin, and can effectively improve the flame retardant properties of the material.

[0044] The flame retardant mechanism of cyanamide flame retardants primarily works through decomposition, absorbing heat, releasing non-combustible gases to dilute oxygen, and forming an intumescent char layer. In the present invention, the cyanamide flame retardant can be selected from one or more of the group consisting of melamine cyanurate (MCA), melamine, and dicyandiamide. Melamine cyanurate (MCA) is a highly effective cyanamide flame retardant with advantages such as high flame retardant efficiency, low toxicity, and good synergistic effects with other flame retardants, making it a preferred choice in the present invention.

[0045] Inorganic flame retardants have the advantages of long-lasting flame retardancy, non-toxicity, and environmental friendliness. Their flame retardant mechanism is mainly achieved through endothermic decomposition, release of non-combustible gases such as water vapor, and formation of a protective layer on the surface of the material. In the present invention, the inorganic flame retardant is selected from one or more of the group consisting of aluminum hydroxide, antimony trioxide, magnesium hydroxide, and zinc borate. Aluminum hydroxide and magnesium hydroxide decompose at high temperatures to produce a large amount of water vapor, while absorbing a large amount of heat, which can effectively reduce the temperature of the material surface and inhibit the combustion reaction; antimony trioxide itself has a limited flame retardant effect, but when used in combination with other flame retardants (such as phosphate flame retardants), it can produce a significant synergistic flame retardant effect; zinc borate has good smoke suppression and flame retardant properties, which can further enhance the flame retardant effect of the material.

[0046] According to the technical solution of the present invention, by compounding a phosphate flame retardant, a cyanamide flame retardant, and an inorganic flame retardant in a weight ratio of 1:0.5-0.8:2-2.5, an optimal synergistic flame retardant effect can be achieved. Within this ratio range, the three flame retardants each play their respective advantages and complement each other to form a highly effective flame retardant system. Specifically, the phosphate flame retardant can exert a flame retardant effect in both the gas phase and the condensed phase, the cyanamide flame retardant can promote the formation and expansion of the char layer, and the inorganic flame retardant enhances the flame retardant effect by absorbing heat and releasing non-combustible gases.

[0047] In a particularly preferred embodiment of the present invention, the composite flame retardant comprises triphenyl phosphate (TPP), melamine cyanurate (MCA), and aluminum hydroxide in a weight ratio of 1:0.6-0.65:2.3-2.5. Experiments have shown that using this specific ratio of composite flame retardants can achieve optimal flame retardancy in the flame-retardant composition, significantly improving its limiting oxygen index (LOI), meeting the stringent flame retardancy requirements of new energy vehicle power batteries.

[0048] According to the technical solution of the present invention, the flame-retardant composition contains 10-20% by weight of a thermal conductor. During the operation of new energy vehicle power batteries, a large amount of heat is generated. If it cannot be dissipated in time, the battery temperature will rise, affecting the performance and life of the battery, and even causing safety accidents. Therefore, the flame-retardant material used in power batteries needs to have not only good flame retardancy but also excellent thermal conductivity.

[0049] In the present invention, the thermal conductor is preferably selected from one or more of the group consisting of graphene, aluminum powder, nickel powder, carbon nanotubes, and carbon fibers. These thermal conductors have high thermal conductivity coefficients and can form an effective heat conduction network within the material, improving the material's thermal conductivity and promptly transferring heat generated by the battery.

[0050] Graphene, a two-dimensional material composed of carbon atoms, has an extremely high thermal conductivity (over 5000 W / m•K), making it one of the best known thermally conductive materials. Adding graphene as a thermal conductor to flame-retardant compositions can significantly improve the material's thermal conductivity. Aluminum powder and nickel powder are common metal thermal conductors with excellent thermal and electrical conductivity, effectively enhancing the material's thermal conductivity. Carbon nanotubes and carbon fibers also possess excellent thermal and mechanical properties. Their addition to materials not only improves thermal conductivity but also enhances mechanical properties.

[0051] The amount of thermal conductive agent added has a significant impact on the thermal conductivity and mechanical properties of the material. When the addition amount is too small, an effective thermal conductive network cannot be formed, and the thermal conductivity of the material is limited. When the addition amount is too large, the thermal conductive agent will be unevenly dispersed in the matrix resin, and agglomeration will easily occur, thereby affecting the mechanical properties and processing performance of the material. The present invention selects a thermal conductive agent addition amount of 10-20% by weight, which can ensure that the material has good thermal conductivity while avoiding adverse effects on its mechanical properties and processing performance.

[0052] According to the technical solution of the present invention, the flame retardant composition contains 5-10% by weight of a silane coupling agent. A silane coupling agent is a compound with an amphiphilic structure, and its molecules contain groups that can bind to inorganic materials (such as flame retardants, thermal conductors) and groups that can bind to organic materials (such as matrix resins). Adding a silane coupling agent to the flame retardant composition can improve the interfacial compatibility between the flame retardant, thermal conductor and matrix resin, and enhance the bonding force between them. Specifically, the silane coupling agent can bind to groups such as hydroxyl groups on the surface of the flame retardant and thermal conductor through chemical adsorption or chemical reaction, while its organic group can chemically react or physically entangle with the matrix resin, thereby establishing an effective chemical bond connection between the inorganic filler and the organic matrix. This can not only improve the dispersibility of the flame retardant and thermal conductor in the matrix resin and avoid agglomeration, but also enhance the interfacial bonding strength of the material, thereby improving its mechanical properties and processing performance while ensuring the flame retardant and thermal conductivity of the material.

[0053] Preferably, the silane coupling agent can be selected from one or more of the group consisting of vinyltriethoxysilane, γ-aminopropyltriethoxysilane, vinyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane. These silane coupling agents have good coupling effect and stability and can meet the use requirements of the present invention. The amount of silane coupling agent added also needs to be reasonably controlled. If the amount added is too small, the compatibility between the components cannot be fully improved; if the amount added is too large, too many interfaces may be formed in the material, which will have an adverse effect on the performance of the material. The present invention selects an amount of 5-10% by weight of silane coupling agent to achieve the best modification effect.

[0054] According to the technical solution of the present invention, the flame retardant composition contains 1-3% by weight of a lubricant. Lubricants play an important role in the processing of flame retardant compositions. Their main functions are to improve the melt fluidity of the material, reduce friction and adhesion between the material and processing equipment, and improve the demolding performance of the material, thereby ensuring the smooth progress of the processing process and improving the quality of the product. According to the technical solution of the present invention, preferably, the lubricant can be selected from one or more of the group consisting of stearic acid, calcium stearate and paraffin. Stearic acid and calcium stearate are commonly used metal soap lubricants with good lubrication effect and thermal stability; paraffin is a hydrocarbon lubricant that can effectively reduce the melt viscosity of the material and improve its fluidity. The amount of lubricant added is usually small, and excessive addition may cause a decrease in the mechanical properties of the material, such as tensile strength, flexural strength, etc. The present invention selects a lubricant addition amount of 1-3% by weight, which can not only meet the requirements of the processing process for lubrication performance, but also will not have a significant adverse effect on other properties of the material.

[0055] According to certain preferred embodiments of the present invention, the flame retardant composition further comprises 1-3 wt% of an antioxidant based on its total weight. During processing and use, the flame retardant composition is affected by factors such as heat and oxygen, and is prone to oxidative degradation, resulting in a decrease in the performance of the material. The addition of an antioxidant can inhibit or delay the oxidation process of the material, thereby improving the thermal stability and service life of the material. The antioxidant is preferably a mixture of a hindered phenol antioxidant and a phosphite antioxidant in a weight ratio of 1:1-2:1. Hindered phenol antioxidants are a type of highly efficient primary antioxidant that can capture free radicals and terminate the chain growth of the oxidation reaction; phosphite antioxidants are a type of auxiliary antioxidant that can decompose hydroperoxides to prevent them from further decomposing and producing free radicals. The combination of the two in a specific ratio can produce a synergistic antioxidant effect and significantly improve the antioxidant properties of the material. Preferably, the hindered phenol antioxidant can be selected from one or more of the group consisting of 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol and 2,4,6-tri-tert-butylphenol; the phosphite antioxidant can be selected from one or more of the group consisting of pentaerythritol diisodecyl diphosphite, triphenyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite and diphenyl isodecyl phosphite.

[0056] According to certain preferred embodiments of the present invention, the flame retardant composition further comprises a colorant to meet different appearance requirements. Preferably, the flame retardant composition comprises no more than 2% by weight of the colorant based on its total weight. The amount of colorant added should not be excessive, as it may affect other properties of the material. The colorant can be a commonly used coloring substance such as an organic pigment or an inorganic pigment, and the specific type can be selected according to actual needs.

[0057] There is no particular limitation on the method for preparing the flame retardant composition that can be used in the present invention. Specifically, it may include the following steps: The components are weighed according to the formula ratio, including 50-68 weight% of the base resin (polycarbonate and polyphenylene ether are mixed at a ratio of 1:1-3:1), 15-28 weight% of the composite flame retardant (phosphate, cyanamide and inorganic flame retardant are mixed at a ratio of 1:0.5-0.8:2-2.5), 10-20 weight% of the thermal conductor, 5-10 weight% of the silane coupling agent, 1-3 weight% of the lubricant, and optionally 1-3 weight% of the antioxidant and 2 weight% or less of the colorant. Then, all the components are added to a high-speed mixer and heated and mixed to obtain a mixture. The mixture is added to a twin-screw extruder for melt blending and extrusion. Finally, the extruded material is cooled with water and pelletized to obtain flame retardant composition particles.

[0058] According to another aspect of the present invention, a flame retardant layer is provided, comprising the flame retardant composition described above. The flame retardant layer is prepared by subjecting the flame retardant composition to an appropriate processing technique (such as extrusion molding, injection molding, tape casting, etc.).

[0059] The thickness of the flame-retardant layer is in the range of 0.5 mm to 5 mm, preferably 1 mm to 3 mm. The thickness of the flame-retardant layer has a significant impact on its performance. If the thickness is too thin, it may not provide sufficient flame retardancy and mechanical strength; if the thickness is too thick, it will increase the weight and volume of the power battery, affecting the battery's energy density. Selecting a thickness range of 0.5 mm to 5 mm, especially the preferred range of 1 mm to 3 mm, can ensure good performance of the flame-retardant layer while meeting the requirements of lightweight and miniaturized power batteries.

[0060] The flame-retardant layer prepared from the flame-retardant composition of the present invention exhibits excellent flame retardancy, thermal conductivity, and mechanical properties. Its limiting oxygen index (LOI) can reach over 27%, meeting the flame retardancy requirements of new energy vehicle power batteries. Its thermal conductivity (W / m·K) can reach over 0.4 W / m·K, effectively dissipating heat generated by the battery. Its tensile strength (MPa) can reach over 12 MPa, and its flexural strength (MPa) can reach over 120 MPa, providing the required basic mechanical strength to withstand the various external forces to which the battery is subjected during installation and use.

[0061] According to another aspect of the present invention, a new energy vehicle power battery is provided, the new energy vehicle power battery comprising: Power battery module; an aluminum shell encapsulating the power battery module; and The flame retardant layer mentioned above is arranged between the power battery module and the aluminum shell and is in contact with them.

[0062] The power battery module is the core part of the power battery of new energy vehicles, responsible for storing and providing electrical energy. The specific composition of the power battery module usually includes a plurality of single cells (such as lithium-ion cells), brackets or shells for fixing and connecting the cells, and tabs, busbars and other components for realizing electrical connection between the cells. These components together constitute an overall module structure that can stably output electrical energy. The aluminum shell has good thermal conductivity and mechanical strength, can protect the battery module, and contribute to the heat dissipation of the battery. The flame retardant layer of the present invention is arranged between the battery module and the aluminum shell, which can give full play to its excellent performance: when the battery has thermal runaway, the flame retardant layer can effectively prevent the spread of flames and play a good flame retardant role; at the same time, it can quickly conduct the heat generated by the battery module to the aluminum shell, and then dissipate it to the outside through the aluminum shell to avoid heat accumulation; in addition, the flame retardant layer can also provide a certain buffer and support for the battery module, enhance the structural stability of the battery, and improve the battery's vibration and impact resistance.

[0063] Compared with the prior art in this field, the advantages of the present invention are as follows: 1. Through a specific ratio of polycarbonate and polyphenylene ether mixed matrix resin, as well as a compound system of phosphate esters, cyanamides and inorganic flame retardants, a synergistic improvement in flame retardancy, thermal conductivity and mechanical properties is achieved, overcoming the defects of traditional materials that are difficult to achieve a good balance of performance.

[0064] 2. The synergistic effect of the composite flame retardant can improve the flame retardant effect while reducing the addition amount, avoiding the degradation of material properties caused by the addition of large amounts of flame retardants, and solving the contradiction between flame retardant efficiency and material performance in traditional flame retardant systems.

[0065] 3. The addition of silane coupling agent enhances the compatibility between flame retardant, thermal conductor and matrix resin, which not only ensures flame retardancy and thermal conductivity, but also improves the mechanical strength and processing fluidity of the material, and optimizes the overall interface bonding strength.

[0066] 4. The prepared flame-retardant layer exhibits excellent flame retardancy, thermal conductivity, and mechanical properties, meeting the stringent safety, heat dissipation, and structural stability requirements of new energy vehicle power batteries and possessing significant practical application value.

[0067] 5. The raw materials used in the flame retardant composition of the present invention are all common chemical products on the market. The preparation process is simple and easy, and is suitable for industrial production.

[0068] Example

[0069] In the present invention, unless otherwise specified, all reagents used were commercially available products and were used directly without further purification.

[0070] Table 1 below lists the raw material information used in the examples and comparative examples of the present invention.

[0071] Table 1 Information on raw materials used in the examples and comparative examples of the present invention

[0072] Test Method According to the methods described in detail below, the flame retardant films prepared in the following examples and comparative examples were tested for flame retardancy, thermal conductivity, and mechanical properties (tensile strength and flexural strength).

[0073] Flame retardant performance test Flame retardant performance testing is conducted in accordance with GB / T 2406-1993. GB / T 2406-1993 is used to determine the minimum oxygen concentration (oxygen index) required for a material to burn in a mixed flow of oxygen and nitrogen, thereby evaluating the material's combustion performance.

[0074] According to the general industry standard GB / T2406-1993 for limiting oxygen index (LOI) testing of flame-retardant thermal conductive materials used in new energy vehicle power batteries, when the LOI reaches 27%, it can be considered that the flame-retardant thermal conductive material meets the basic requirements for flame retardancy of new energy vehicle power batteries; and when the LOI reaches above 30%, it can be considered that the flame-retardant thermal conductive material has excellent flame retardancy.

[0075] Thermal conductivity test Thermal conductivity testing was performed according to ASTM E1461, a standard test method for determining the thermal diffusivity of solid materials based on the flash method.

[0076] According to ASTM E1461, a general industry standard for thermal conductivity testing of flame-retardant thermally conductive materials used in new energy vehicle power batteries, when the thermal conductivity (W / m·K) reaches or exceeds 0.4 W / (m·K), the flame-retardant thermally conductive material can be considered to meet the basic thermal conductivity requirements of new energy vehicle power batteries; and when the thermal conductivity (W / m·K) reaches or exceeds 3 W / (m·K), the thermally conductive material can be considered to have excellent thermal conductivity.

[0077] Tensile strength test Tensile strength is tested according to GB / T1040.1-2006. GB / T 1040.1-2006 is applicable to tensile property testing of plastics and composite materials, especially in the field of automotive batteries.

[0078] According to the general industry standard GB / T 1040.1-2006 for tensile strength testing of flame-retardant thermally conductive materials used in new energy vehicle power batteries, when the tensile strength (MPa) reaches 12 MPa, it can be considered that the flame-retardant thermally conductive material meets the basic requirements of new energy vehicle power batteries regarding mechanical properties related to tensile properties; and when the tensile strength (MPa) reaches above 30 MPa, it can be considered that the flame-retardant thermally conductive material has excellent performance in mechanical properties related to tensile properties.

[0079] Bending strength test The flexural strength was measured according to ISO 178-93.

[0080] According to ISO 178-93, a general industry standard for flexural strength testing of flame-retardant thermally conductive materials used in new energy vehicle power batteries, when the flexural strength (MPa) reaches 120 MPa, the flame-retardant thermally conductive material can be considered to meet the basic requirements of new energy vehicle power batteries regarding mechanical properties related to flexural performance; and when the flexural strength (MPa) reaches above 300 MPa, the flame-retardant thermally conductive material can be considered to have excellent mechanical properties related to flexural performance.

[0081] Example 1 (E1) Weigh the following components by weight: PC (30,000) and PPO (15,000) totaling 55 wt% in a weight ratio of 1:1; TPP, MCA and Al(OH)3 in a total amount of 18 wt% in a weight ratio of 1:0.6:2.5; 15 wt% of graphene, a thermal conductor; 10 wt% of the silane coupling agent vinyltriethoxysilane; and 2% by weight of lubricant calcium stearate.

[0082] The above components were added into a high-speed mixer and mixed at 80° C. for 10 min to obtain a mixed material.

[0083] The mixed material was added into a twin-screw extruder, and the extrusion temperature was set as follows: 220°C for zone 1, 230°C for zone 2, 240°C for zone 3, 250°C for zone 4, 260°C for zone 5, and 260°C for zone 6, the die temperature was 250°C, and the screw speed was 300 r / min for melt blending and extrusion.

[0084] The extruded material is cooled by water and then pelletized to obtain flame retardant material pellets.

[0085] The flame retardant material particles prepared above were made into a flame retardant film 1 with a thickness of 1 mm through a tape casting process.

[0086] Then, the flame retardant film 1 was tested for flame retardancy, thermal conductivity and mechanical properties (tensile strength and flexural strength) according to the methods for measuring flame retardancy, thermal conductivity and mechanical properties (tensile strength and flexural strength) described in detail above, and the test results are shown in Table 2 below.

[0087] Examples 2-9 (E2-E9) and Comparative Examples 1-10 (CE1-CE10) Flame retardant films 2-9 and comparative flame retardant films 1-10 were prepared in a similar manner to Example 1 above, except that the raw material ratios were changed as shown in Table 2 or Table 3 below.

[0088] Then, the flame retardant films 2-9 and the comparative flame retardant films 1-10 were tested for flame retardant properties, thermal conductivity and mechanical properties (tensile strength and flexural strength) according to the methods for measuring flame retardant properties, thermal conductivity and mechanical properties (tensile strength and flexural strength) described in detail above, and the test results are shown in Table 2 or Table 3 below.

[0089] Table 2 Component ratios and performance test results of the flame retardant compositions of Examples 1-9 (E1-E9)

[0090] Table 3 Component ratios and performance test results of the flame retardant compositions of Comparative Examples 1-10 (CE1-CE10)

[0091] As shown in Table 3 and Table 2 shown above, when the base resin, composite flame retardant, thermal conductor, silane coupling agent and lubricant of specific content and composition are selected within the scope of the present invention, a flame retardant composition with good flame retardancy, thermal conductivity and mechanical properties (tensile strength and flexural strength) can be obtained, and the flame retardant composition is suitable for use as a flame retardant layer between a battery module and an aluminum shell of a new energy vehicle power battery. In particular, by comparing the results of Examples 1-5 with those of Examples 6-9, by further controlling the weight-average molecular weight of polycarbonate and polyphenylene ether and selecting a specific weight ratio of triphenyl phosphate (TPP) of 1:0.6-0.65:2.3-2.5, melamine cyanurate (MCA) and aluminum hydroxide, it is possible to simultaneously obtain excellent results in terms of flame retardancy, thermal conductivity and mechanical properties (tensile strength and flexural strength).

[0092] Although specific embodiments have been shown and described in the present invention, it will be understood by those skilled in the art that various alternative and / or equivalent embodiments may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to include any improvements or changes to the specific embodiments discussed in the present invention. It will be understood by those skilled in the art that various modifications and changes may be made without departing from the scope of the present invention.

Claims

1. A flame retardant composition, characterized in that The flame retardant composition comprises, based on its total weight: 50-68 wt% of a base resin, wherein the base resin is a mixture of polycarbonate and polyphenylene ether in a weight ratio of 1:1-3:1; 15-28 wt % of a composite flame retardant, the composite flame retardant comprising a phosphate flame retardant, a cyanamide flame retardant, and an inorganic flame retardant in a weight ratio of 1:0.5-0.8:2-2.5, wherein the inorganic flame retardant is selected from one or more of the group consisting of aluminum hydroxide, antimony trioxide, magnesium hydroxide, and zinc borate; 10-20 wt% of a thermal conductor; 5-10 wt% of a silane coupling agent; and 1-3 wt% lubricant.

2. The flame retardant composition according to claim 1, wherein: The polycarbonate has a weight average molecular weight in the range of 30,000-40,000 g / mol; and / or The polycarbonate is one or more selected from the group consisting of bisphenol A polycarbonate, bisphenol S polycarbonate, organosilicon-modified polycarbonate and polyester-modified polycarbonate; and / or The weight average molecular weight of the polyphenylene ether is in the range of 10,000-25,000 g / mol.

3. The flame retardant composition according to claim 1, wherein: The phosphate flame retardant is selected from one or more of the group consisting of triphenyl phosphate, tricresyl phosphate and tri(2-ethylhexyl) phosphate; and / or The cyanamide flame retardant is selected from one or more of the group consisting of melamine cyanurate, melamine and dicyandiamide; and / or The silane coupling agent is one or more selected from the group consisting of vinyltriethoxysilane, γ-aminopropyltriethoxysilane, vinyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane.

4. The flame retardant composition according to claim 1, characterized in that The composite flame retardant comprises triphenyl phosphate, melamine cyanurate and aluminum hydroxide in a weight ratio of 1:0.6-0.65:2.3-2.

5.

5. The flame retardant composition according to claim 1, wherein: The thermal conductor is selected from one or more of the group consisting of graphene, aluminum powder, nickel powder, carbon nanotubes and carbon fibers; and / or The lubricant is selected from one or more of the group consisting of stearic acid, calcium stearate and paraffin.

6. The flame retardant composition according to claim 1, characterized in that The flame retardant composition further comprises 1 to 3 wt% of an antioxidant based on the total weight of the flame retardant composition.

7. The flame retardant composition according to claim 6, wherein The antioxidant is a mixture of a hindered phenol antioxidant and a phosphite antioxidant in a weight ratio of 1:1-2:1, wherein the hindered phenol antioxidant is selected from one or more of the group consisting of 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol and 2,4,6-tri-tert-butylphenol, and the phosphite antioxidant is selected from one or more of the group consisting of pentaerythritol diisodecyl diphosphite, triphenyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite and diphenyl isodecyl phosphite.

8. The flame retardant composition according to claim 1, characterized in that The flame retardant composition includes 2 wt % or less of a colorant based on the total weight of the flame retardant composition.

9. A flame retardant layer, characterized in that: The flame retardant layer comprises the flame retardant composition according to any one of claims 1 to 8, and has a thickness in the range of 0.5 mm to 5 mm.

10. A new energy vehicle power battery, characterized in that: The new energy vehicle power battery includes: Power battery module; an aluminum shell encapsulating the power battery module; and The flame-retardant layer according to claim 9, wherein the flame-retardant layer is disposed between the power battery module and the aluminum shell and in contact therewith.

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