Thermal-insulation flame-retardant lightweight silicone rubber based on power battery and preparation method thereof

Abstract

The invention relates to the technical field of silicone rubber, in particular to thermal-insulation flame-retardant lightweight silicone rubber based on a power battery and a preparation method of the thermal-insulation flame-retardant lightweight silicone rubber based on the power battery, and the thermal-insulation flame-retardant lightweight silicone rubber comprises the following components in parts by weight: 60-100 parts of modified methyl vinyl silicone rubber; 5 to 15 parts of graphene aerogel; 10 to 30 parts of a microencapsulated phase change material; 40 to 60 parts of modified nano magnesium hydroxide; 1-5 parts of a functionalized carbon nanotube; 3 to 8 parts of organic modified montmorillonite; 5-15 parts of zinc borate; 2 to 6 parts of epoxy group modified polysiloxane; the graphene aerogel with a three-dimensional network structure is introduced, so that a'hot labyrinth 'effect is formed, and the heat conductivity coefficient of the material is remarkably reduced; a microencapsulated phase-change material is adopted, so that intelligent temperature regulation and control and long-term stability are realized; the surface-modified nano magnesium hydroxide is used, so that the compatibility with a silicone rubber matrix is improved while the flame retardance is provided.

Description

Technical Field

[0001] The present invention relates to the technical field of silicone rubber, and in particular to a heat-insulating, flame-retardant and lightweight silicone rubber based on a power battery and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of the new energy vehicle industry, the safety and performance optimization of power batteries have become a hot topic of global concern. Power batteries are vulnerable to high temperature environments or internal thermal runaway during use, which not only has a negative impact on the performance and life of the battery, but may also cause serious safety accidents. Therefore, the development of materials that are both heat-insulating, flame-retardant, lightweight and have high mechanical properties is of great significance to improving the safety and stability of power battery systems. In this field, silicone rubber, as an important polymer material, is widely used in heat insulation and flame retardant protection of battery packs due to its excellent thermal stability, weather resistance and mechanical properties.

[0003] Traditional power battery protection materials are difficult to meet the increasingly stringent requirements in terms of heat insulation, flame retardancy, lightweight and long-term stability. At present, the heat insulation and flame retardant materials commonly used in the industry mainly include flame retardant silica gel and PET film, which are usually compounded with aerogel to form a heat insulation layer. However, these materials have many shortcomings.

[0004] First, although conventional flame-retardant silicone has certain flame retardancy, its density is usually as high as 1.5g / cm 3 It is not conducive to the lightweight design of electric vehicles. Secondly, in order to improve the flame retardant performance, a large amount of flame retardant fillers are usually added, which inevitably leads to a significant decrease in the physical and mechanical properties of the material and affects the overall structural stability of the battery pack. Furthermore, the thermal insulation effect of traditional materials is limited, and it is difficult to effectively deal with extreme situations such as battery overheating and thermal runaway. In addition, existing materials are prone to performance degradation during long-term use, and it is difficult to meet the safety requirements of the power battery throughout its life cycle.

[0005] The existing technology usually uses inorganic fillers to modify silicone rubber to improve the flame retardant properties of the material. However, this method often makes the material brittle, increases the thermal conductivity, and makes it difficult to achieve multifunctional integration. Another common technical route is to use intumescent flame retardants, but they will produce a lot of smoke at high temperatures, which is not conducive to safe evacuation when the battery fails.

[0006] In the prior art, composite materials based on silicone rubber have shown certain potential. For example, in the research paper "Effect of Ceramifiable Silicone Rubber Composite Based Thermal Insulators in Battery Packs" published in the journal "SAE Technical Paper Series" by Praveen Kumar Nambisan TM et al. (2024), the application of ceramic silicone rubber composites (CSRCs) in the protection of thermal runaway propagation of power batteries was discussed. Studies have shown that this type of material effectively delays the propagation of thermal runaway by forming a ceramic protective layer under high temperature conditions. However, this technology has obvious shortcomings in lightweight design. Its ceramic protective layer relies on the addition of high-density fillers, which leads to an increase in material density, and fails to fully consider the dynamic balance between thermal conductivity regulation and thermal insulation performance. In addition, the literature lacks a detailed explanation of the preparation methods of key components and their synergistic effects, so that the potential for optimizing material performance has not been fully explored.

[0007] Another related study was published by S. Shi et al. (2020) in the journal Progress in Organic Coatings, with the title "Thermal decomposition behavior of a thermal protection coating composite with silicone rubber: Experiment and modeling". The paper focuses on the thermal decomposition behavior and kinetic model of thermal protection coating composites based on silicone rubber. Studies have shown that by introducing the coating process, silicone rubber-based composites exhibit good thermal stability under high temperature environments. However, the coating scheme proposed in the literature is mainly applicable to the field of thermal protection of spacecraft, and fails to fully consider the lightweight and multifunctional design requirements in the actual working conditions of power batteries. In addition, this technology is limited to the improvement of the surface properties of the coating material, and does not involve the structural optimization of the core material and the realization of the multifunctional synergistic effect, which limits its application in the field of thermal management of power batteries.

[0008] In summary, although the existing technology has achieved the optimization of specific functions in the development of heat-insulating and flame-retardant materials based on silicone rubber, there are still many technical bottlenecks in terms of material lightweighting, multifunctional collaborative design and key component preparation. These shortcomings make it impossible for existing materials to simultaneously meet the comprehensive requirements of safety, performance and lightweight in power battery systems. Summary of the invention

[0009] In view of the shortcomings of the prior art, the present invention proposes a thermal insulation and flame retardant lightweight silicone rubber for power batteries and a preparation method thereof. The material cleverly solves the contradiction between lightweight, efficient thermal insulation, excellent flame retardant performance and good physical and mechanical properties through the coordinated design of multiple components.

[0010] The object of the present invention is to provide a heat-insulating, flame-retardant, lightweight silicone rubber for power batteries and a preparation method thereof, which comprises the following components in parts by weight:

[0011] Modified methyl vinyl silicone rubber 60-100 parts;

[0012] 5-15 parts of graphene aerogel;

[0013] 10-30 parts of microencapsulated phase change material;

[0014] 40-60 parts of modified nano magnesium hydroxide;

[0015] 1-5 parts of functionalized carbon nanotubes;

[0016] 3-8 parts of organic modified montmorillonite;

[0017] 5-15 parts of zinc borate;

[0018] 2-6 parts of epoxy-modified polysiloxane;

[0019] Platinum catalyst 0.1-0.5 parts.

[0020] Specifically, the preparation method of the modified methyl vinyl silicone rubber comprises the following steps:

[0021] (1) Add 100 parts by weight of methyl vinyl silicone rubber into a three-necked round-bottom flask;

[0022] (2) under nitrogen protection, slowly dropwise adding 5-7 parts by weight of phenyl dichlorophosphine;

[0023] (3) heating to 80-90°C and stirring for 4-6 hours;

[0024] (4) cooling to room temperature, precipitating the product with methanol, and centrifuging;

[0025] (5) The product was dried under vacuum at 60°C for 12 hours.

[0026] Specifically, the method for preparing the graphene aerogel comprises the following steps:

[0027] (1) preparing a 2 mg / mL graphene oxide aqueous dispersion;

[0028] (2) adding L-ascorbic acid in an amount equal to that of graphene oxide and ultrasonically dispersing for 30 minutes;

[0029] (3) The mixture was transferred to a stainless steel autoclave and subjected to hydrothermal reaction at 170°C for 12 hours;

[0030] (4) Cool to room temperature and quick freeze with liquid nitrogen;

[0031] (5) Freeze-drying for 48 hours to obtain graphene aerogel.

[0032] Specifically, the preparation method of the microencapsulated phase change material comprises the following steps:

[0033] (1) Dissolve 2 parts by weight of chitosan in 100 mL of 2% acetic acid solution;

[0034] (2) Dissolve 2 parts by weight of sodium alginate in 100 mL of deionized water;

[0035] (3) adding 20 parts by weight of n-octadecane to the chitosan solution and emulsifying at high speed for 10 minutes;

[0036] (4) adding the emulsion dropwise into the sodium alginate solution and stirring for 2 hours to form microcapsules;

[0037] (5) solidify with 0.5% calcium chloride solution for 1 hour, filter and wash with water;

[0038] (6) Vacuum drying at 60°C for 12 hours.

[0039] Specifically, the preparation method of the modified nano magnesium hydroxide comprises the following steps:

[0040] (1) Dispersing 100 parts by weight of nano magnesium hydroxide in 500 mL of anhydrous ethanol;

[0041] (2) adding 3-5 parts by weight of γ-glycidyloxypropyltrimethoxysilane;

[0042] (3) reflux at 80°C with stirring for 4 hours;

[0043] (4) filtration and ethanol washing;

[0044] (5) Vacuum drying at 100°C for 6 hours.

[0045] Specifically, the method for preparing the functionalized carbon nanotubes comprises the following steps:

[0046] (1) Add 1 part by weight of multi-walled carbon nanotubes into 100 mL of mixed acid (H2SO4:HNO3=3:1, volume ratio);

[0047] (2) ultrasonic treatment for 2 hours and reflux at 80°C for 6 hours;

[0048] (3) cooling, centrifugation, and washing with deionized water until neutral;

[0049] (4) Dispersing the product in 100 mL of water, adding 10 parts by weight of urea;

[0050] (5) Hydrothermal reaction at 180°C for 12 hours;

[0051] (6) Cooling, filtering, and washing;

[0052] (7) Vacuum drying at 80°C for 12 hours.

[0053] Specifically, the modified methyl vinyl silicone rubber is a terminal diphenylphosphonyl-modified polydimethylsiloxane-polymethyl vinyl siloxane copolymer, the vinyl content of which is 0.15-0.20 mol % and the number average molecular weight is 500,000-600,000 g / mol.

[0054] Specifically, the graphene aerogel is reduced graphene oxide aerogel with a density of 5-10 mg / cm 3 , with a specific surface area of ​​400-600m 2 / g; the microencapsulated phase change material is n-octadecane wrapped in chitosan / sodium alginate composite microcapsules, the average particle size of the microcapsules is 20-30μm, and the phase change temperature is 28-30°C; the modified nano magnesium hydroxide is γ-glycidyloxypropyltrimethoxysilane modified nano magnesium hydroxide, the average particle size is 30-50nm, the specific surface area is 60-80m 2 / g; the functionalized carbon nanotubes are carboxylated nitrogen-doped multi-walled carbon nanotubes having an outer diameter of 10-20 nm, a length of 10-30 μm, and a nitrogen doping amount of 2-3 at%.

[0055] The method for preparing the silicone rubber comprises the following steps:

[0056] (1) First, add the modified methyl vinyl silicone rubber and epoxy-modified polysiloxane into a vacuum kneader and stir for 30-40 minutes at 90-110° C. and a vacuum degree of 0.1-0.5 kPa;

[0057] (2) Secondly, cool down to 70-80°C, add graphene aerogel, microencapsulated phase change material, and modified nano magnesium hydroxide in sequence, and stir for 10-15 minutes after each component is added;

[0058] (3) Then, adding functionalized carbon nanotubes, organic modified montmorillonite and zinc borate, and continuing to mix for 60-90 minutes under a vacuum degree of 0.05-0.1 kPa;

[0059] (4) Again, the mixture was cooled to 75-85° C., and the platinum catalyst was quickly added under nitrogen protection, and stirred for 3-7 minutes;

[0060] (5) Finally, the mixture is transferred to a mold preheated to 100-110°C, hot-pressed at 115-125°C for 25-35 minutes under a pressure of 5-10 MPa, then slowly cooled to room temperature and demolded to obtain the product.

[0061] Specifically, the method further comprises the following post-processing steps:

[0062] The molded product is vacuum cured at 80-90°C for 4-6 hours and then left to stand at room temperature for 24-48 hours.

[0063] The present invention has the following beneficial effects:

[0064] 1. Introducing graphene aerogel with a three-dimensional network structure to form a "thermal maze" effect, significantly reducing the thermal conductivity of the material;

[0065] 2. Use microencapsulated phase change materials to achieve intelligent temperature control and long-term stability;

[0066] 3. The use of surface-modified nano magnesium hydroxide improves the compatibility with the silicone rubber matrix while providing flame retardancy;

[0067] 4. Introduce functionalized carbon nanotubes to build a conductive network and improve the thermal conductivity and mechanical properties of the material;

[0068] 5. An innovative multi-step mixing process is designed to ensure uniform dispersion of each component and give full play to the synergistic effect.

[0069] From a molecular level, the present invention cleverly utilizes the interaction between different components. For example, the diphenylphosphonyl end groups introduced into the modified methyl vinyl silicone rubber not only improve the flame retardancy, but also form a π-π stacking effect with the graphene aerogel to enhance the interface bonding. The chitosan / sodium alginate composite wall material of the microencapsulated phase change material forms a hydrogen bond with the silicone rubber matrix, which improves the encapsulation stability of the phase change material. The carboxyl groups on the surface of the functionalized carbon nanotubes undergo a condensation reaction with the siloxy groups in the silicone rubber to form covalent bonds, further enhancing the mechanical properties of the material.

[0070] This multi-component collaborative design not only solves the defects of traditional materials, but also produces a series of unexpected technical effects. For example, the material exhibits adaptive thermal management capabilities and exhibits different thermal conductivity behaviors at different temperatures. In addition, the synergy of graphene aerogel and functionalized carbon nanotubes also gives the material excellent electromagnetic shielding properties, providing additional protection for power batteries.

[0071] In summary, the present invention has successfully developed a new type of power battery protection material with lightweight, high-efficiency heat insulation, excellent flame retardant properties and good physical and mechanical properties through innovative material design and preparation process. This multifunctional integrated design concept not only solves many deficiencies of the existing technology, but also provides a new technical route for the field of power battery safety protection, which is expected to be widely used in electric vehicles, energy storage systems and other fields, and promote the sustainable development of the new energy industry. DETAILED DESCRIPTION

[0072] Example 1

[0073] This embodiment provides a heat-insulating, flame-retardant, lightweight silicone rubber for power batteries and a preparation method thereof. The silicone rubber is composed of the following components (by weight): 60 parts of modified methyl vinyl silicone rubber, 5 parts of graphene aerogel, 10 parts of microencapsulated phase change material, 40 parts of modified nano magnesium hydroxide, 1 part of functionalized carbon nanotubes, 3 parts of organically modified montmorillonite, 5 parts of zinc borate, 2 parts of epoxy-modified polysiloxane, and 0.1 parts of platinum catalyst.

[0074] First, prepare modified methyl vinyl silicone rubber. Add 100 parts by weight of methyl vinyl silicone rubber (vinyl content 0.15 mol%, number average molecular weight 500,000 g / mol) into a three-necked round-bottom flask. Under nitrogen protection, slowly add 5 parts by weight of phenyl dichlorophosphine. Raise the reaction temperature to 80°C and stir the reaction for 4 hours. Subsequently, cool to room temperature, precipitate the product with methanol, and separate by centrifugation. Finally, vacuum dry the product at 60°C for 12 hours to obtain the desired modified methyl vinyl silicone rubber.

[0075] Secondly, prepare graphene aerogel. Prepare 2 mg / mL graphene oxide aqueous dispersion, add equal mass of L-ascorbic acid, and ultrasonically disperse for 30 minutes. Transfer the mixture to a stainless steel autoclave and hydrothermally react at 170°C for 12 hours. After cooling to room temperature, quick freeze with liquid nitrogen, and then freeze-dry for 48 hours to obtain a density of 5 mg / cm 3 , with a specific surface area of ​​400m 2 / g of graphene aerogel.

[0076] Next, prepare a microencapsulated phase change material. Dissolve 2 parts by weight of chitosan in 100 mL of 2% acetic acid solution, and dissolve 2 parts by weight of sodium alginate in 100 mL of deionized water. Add 20 parts by weight of n-octadecane to the chitosan solution and emulsify at high speed for 10 minutes. Add the emulsion dropwise into the sodium alginate solution and stir for 2 hours to form microcapsules. Cured with 0.5% calcium chloride solution for 1 hour, filtered, and washed with water. Finally, vacuum dried at 60°C for 12 hours to obtain a microencapsulated phase change material with an average particle size of 20 μm and a phase change temperature of 28°C.

[0077] Then, the modified nano magnesium hydroxide was prepared. 100 parts by weight of nano magnesium hydroxide was dispersed in 500 mL of anhydrous ethanol, and 3 parts by weight of γ-glycidyloxypropyltrimethoxysilane was added. The mixture was stirred at 80°C for 4 hours, filtered, and washed with ethanol. Finally, the mixture was vacuum dried at 100°C for 6 hours to obtain a product with an average particle size of 30 nm and a specific surface area of ​​60 m 2 / g of modified nano magnesium hydroxide.

[0078] Again, functionalized carbon nanotubes were prepared. 1 part by weight of multi-walled carbon nanotubes was added to 100 mL of mixed acid (H2SO4:HNO3=3:1, volume ratio), ultrasonically treated for 2 hours, and refluxed at 80°C for 6 hours. After cooling, centrifugation was performed and washed with deionized water until neutral. The product was dispersed in 100 mL of water, 10 parts by weight of urea was added, and hydrothermally reacted at 180°C for 12 hours. After cooling, filtering, and washing with water, vacuum drying was performed at 80°C for 12 hours to obtain functionalized carbon nanotubes with an outer diameter of 10 nm, a length of 10 μm, and a nitrogen doping amount of 2 at%.

[0079] Finally, the components prepared above are mixed according to the specified weight parts. First, the modified methyl vinyl silicone rubber and epoxy-modified polysiloxane are added to a vacuum kneader and stirred at 90°C and 0.1kPa vacuum for 30 minutes. Secondly, the temperature is lowered to 70°C, and graphene aerogel, microencapsulated phase change material, and modified nano magnesium hydroxide are added in sequence, and each component is stirred for 10 minutes after addition. Then, functionalized carbon nanotubes, organic modified montmorillonite and zinc borate are added, and mixing is continued for 60 minutes at 0.05kPa vacuum. Again, the mixture is cooled to 75°C, and the platinum catalyst is quickly added under nitrogen protection and stirred for 3 minutes. Finally, the mixture is transferred to a mold preheated to 100°C, hot-pressed at 115°C for 25 minutes under a pressure of 5MPa, and then slowly cooled to room temperature and demolded to obtain the product.

[0080] Preferably, in an embodiment of the present invention, the molded product is vacuum post-cured at 80° C. for 4 hours and then left to stand at room temperature for 24 hours to fully stabilize the material properties.

[0081] Example 2

[0082] This embodiment provides another thermal insulation and flame retardant lightweight silicone rubber for power batteries and its preparation method. The silicone rubber is composed of the following components (by weight): 80 parts of modified methyl vinyl silicone rubber, 10 parts of graphene aerogel, 20 parts of microencapsulated phase change material, 50 parts of modified nano magnesium hydroxide, 3 parts of functionalized carbon nanotubes, 5 parts of organic modified montmorillonite, 10 parts of zinc borate, 4 parts of epoxy modified polysiloxane, and 0.3 parts of platinum catalyst.

[0083] First, prepare modified methyl vinyl silicone rubber. Add 100 parts by weight of methyl vinyl silicone rubber (vinyl content 0.175 mol%, number average molecular weight 550,000 g / mol) into a three-necked round-bottom flask. Under nitrogen protection, slowly add 6 parts by weight of phenyl dichlorophosphine. Raise the reaction temperature to 85°C and stir the reaction for 5 hours. Subsequently, cool to room temperature, precipitate the product with methanol, and separate by centrifugation. Finally, vacuum dry the product at 60°C for 12 hours to obtain the desired modified methyl vinyl silicone rubber.

[0084] Secondly, prepare graphene aerogel. Prepare 2 mg / mL graphene oxide aqueous dispersion, add equal mass of L-ascorbic acid, and ultrasonically disperse for 30 minutes. Transfer the mixture to a stainless steel autoclave and hydrothermally react at 170°C for 12 hours. After cooling to room temperature, quick freeze with liquid nitrogen, and then freeze-dry for 48 hours to obtain a density of 7.5 mg / cm 3 , with a specific surface area of ​​500m 2 / g of graphene aerogel.

[0085] Next, prepare a microencapsulated phase change material. Dissolve 2 parts by weight of chitosan in 100 mL of 2% acetic acid solution, and dissolve 2 parts by weight of sodium alginate in 100 mL of deionized water. Add 20 parts by weight of n-octadecane to the chitosan solution and emulsify at high speed for 10 minutes. Add the emulsion dropwise to the sodium alginate solution and stir for 2 hours to form microcapsules. Cured with 0.5% calcium chloride solution for 1 hour, filtered, and washed with water. Finally, vacuum dried at 60°C for 12 hours to obtain a microencapsulated phase change material with an average particle size of 25 μm and a phase change temperature of 29°C.

[0086] Then, the modified nano magnesium hydroxide was prepared. 100 parts by weight of nano magnesium hydroxide was dispersed in 500 mL of anhydrous ethanol, and 4 parts by weight of γ-glycidyloxypropyltrimethoxysilane was added. The mixture was stirred at 80°C for 4 hours, filtered, and washed with ethanol. Finally, the mixture was vacuum dried at 100°C for 6 hours to obtain a product with an average particle size of 40 nm and a specific surface area of ​​70 m 2 / g of modified nano magnesium hydroxide.

[0087] Again, functionalized carbon nanotubes were prepared. 1 part by weight of multi-walled carbon nanotubes was added to 100 mL of mixed acid (H2SO4:HNO3=3:1, volume ratio), ultrasonically treated for 2 hours, and refluxed at 80°C for 6 hours. After cooling, centrifugation was performed and washed with deionized water until neutral. The product was dispersed in 100 mL of water, 10 parts by weight of urea was added, and hydrothermally reacted at 180°C for 12 hours. After cooling, filtering, and washing with water, vacuum drying was performed at 80°C for 12 hours to obtain functionalized carbon nanotubes with an outer diameter of 15 nm, a length of 20 μm, and a nitrogen doping amount of 2.5 at%.

[0088] Finally, the components prepared above are mixed according to the specified weight parts. First, the modified methyl vinyl silicone rubber and epoxy-modified polysiloxane are added to a vacuum kneader and stirred for 35 minutes at 100°C and 0.3kPa vacuum. Secondly, the temperature is lowered to 75°C, and graphene aerogel, microencapsulated phase change material, and modified nano magnesium hydroxide are added in sequence, and each component is stirred for 12 minutes after addition. Then, functionalized carbon nanotubes, organic modified montmorillonite and zinc borate are added, and mixing is continued for 75 minutes at 0.075kPa vacuum. Again, the mixture is cooled to 80°C, and the platinum catalyst is quickly added under nitrogen protection and stirred for 5 minutes. Finally, the mixture is transferred to a mold preheated to 105°C, hot-pressed at 120°C for 30 minutes under a pressure of 7.5MPa, and then slowly cooled to room temperature and demolded to obtain the product.

[0089] Preferably, in an embodiment of the present invention, the molded product is vacuum post-cured at 85° C. for 5 hours and then left to stand at room temperature for 36 hours to fully stabilize the material properties.

[0090] Example 3

[0091] This embodiment provides another thermal insulation and flame retardant lightweight silicone rubber for power batteries and its preparation method. The silicone rubber is composed of the following components (by weight): 90 parts of modified methyl vinyl silicone rubber, 12 parts of graphene aerogel, 25 parts of microencapsulated phase change material, 55 parts of modified nano magnesium hydroxide, 4 parts of functionalized carbon nanotubes, 6 parts of organic modified montmorillonite, 12 parts of zinc borate, 5 parts of epoxy modified polysiloxane, and 0.4 parts of platinum catalyst.

[0092] First, prepare modified methyl vinyl silicone rubber. Add 100 parts by weight of methyl vinyl silicone rubber (vinyl content 0.185 mol%, number average molecular weight 575,000 g / mol) into a three-necked round-bottom flask. Under nitrogen protection, slowly add 6.5 parts by weight of phenyl dichlorophosphine. Raise the reaction temperature to 87°C and stir the reaction for 5.5 hours. Subsequently, cool to room temperature, precipitate the product with methanol, and separate by centrifugation. Finally, vacuum dry the product at 60°C for 12 hours to obtain the desired modified methyl vinyl silicone rubber.

[0093] Secondly, prepare graphene aerogel. Prepare 2 mg / mL graphene oxide aqueous dispersion, add equal mass of L-ascorbic acid, and ultrasonically disperse for 30 minutes. Transfer the mixture to a stainless steel autoclave and hydrothermally react at 170°C for 12 hours. After cooling to room temperature, quick freeze with liquid nitrogen, and then freeze-dry for 48 hours to obtain a density of 8.5 mg / cm 3 , with a specific surface area of ​​550m 2 / g of graphene aerogel.

[0094] Next, prepare a microencapsulated phase change material. Dissolve 2 parts by weight of chitosan in 100 mL of 2% acetic acid solution, and dissolve 2 parts by weight of sodium alginate in 100 mL of deionized water. Add 20 parts by weight of n-octadecane to the chitosan solution and emulsify at high speed for 10 minutes. Add the emulsion dropwise to the sodium alginate solution and stir for 2 hours to form microcapsules. Cured with 0.5% calcium chloride solution for 1 hour, filtered, and washed with water. Finally, vacuum dried at 60°C for 12 hours to obtain a microencapsulated phase change material with an average particle size of 27 μm and a phase change temperature of 29.5°C.

[0095] Then, the modified nano magnesium hydroxide was prepared. 100 parts by weight of nano magnesium hydroxide was dispersed in 500 mL of anhydrous ethanol, and 4.5 parts by weight of γ-glycidyloxypropyltrimethoxysilane was added. The mixture was stirred at 80°C for 4 hours, filtered, and washed with ethanol. Finally, the mixture was vacuum dried at 100°C for 6 hours to obtain a product with an average particle size of 45 nm and a specific surface area of ​​75 m 2 / g of modified nano magnesium hydroxide.

[0096] Again, functionalized carbon nanotubes were prepared. 1 part by weight of multi-walled carbon nanotubes was added to 100 mL of mixed acid (H2SO4:HNO3=3:1, volume ratio), ultrasonically treated for 2 hours, and refluxed at 80°C for 6 hours. After cooling, centrifugation was performed and washed with deionized water until neutral. The product was dispersed in 100 mL of water, 10 parts by weight of urea was added, and hydrothermally reacted at 180°C for 12 hours. After cooling, filtering, and washing with water, vacuum drying was performed at 80°C for 12 hours to obtain functionalized carbon nanotubes with an outer diameter of 17 nm, a length of 25 μm, and a nitrogen doping amount of 2.7 at%.

[0097] Finally, the components prepared above are mixed according to the specified weight parts. First, the modified methyl vinyl silicone rubber and epoxy-modified polysiloxane are added to a vacuum kneader and stirred for 37 minutes at 105°C and 0.4kPa vacuum. Secondly, the temperature is lowered to 77°C, and graphene aerogel, microencapsulated phase change material, and modified nano magnesium hydroxide are added in sequence, and each component is stirred for 13 minutes after addition. Then, functionalized carbon nanotubes, organic modified montmorillonite and zinc borate are added, and mixing is continued for 80 minutes at 0.085kPa vacuum. Again, the mixture is cooled to 82°C, and the platinum catalyst is quickly added under nitrogen protection and stirred for 6 minutes. Finally, the mixture is transferred to a mold preheated to 107°C, hot-pressed at 122°C for 32 minutes under a pressure of 8.5MPa, and then slowly cooled to room temperature and demolded to obtain the product.

[0098] Preferably, in an embodiment of the present invention, the molded product is vacuum post-cured at 87° C. for 5.5 hours and then left to stand at room temperature for 40 hours to fully stabilize the material properties.

[0099] Example 4

[0100] This embodiment provides another thermal insulation and flame retardant lightweight silicone rubber for power batteries and its preparation method. The silicone rubber is composed of the following components (by weight): 100 parts of modified methyl vinyl silicone rubber, 15 parts of graphene aerogel, 30 parts of microencapsulated phase change material, 60 parts of modified nano magnesium hydroxide, 5 parts of functionalized carbon nanotubes, 8 parts of organic modified montmorillonite, 15 parts of zinc borate, 6 parts of epoxy modified polysiloxane, and 0.5 parts of platinum catalyst.

[0101] First, prepare modified methyl vinyl silicone rubber. Add 100 parts by weight of methyl vinyl silicone rubber (vinyl content 0.20 mol%, number average molecular weight 600,000 g / mol) into a three-necked round-bottom flask. Under nitrogen protection, slowly add 7 parts by weight of phenyl dichlorophosphine. Raise the reaction temperature to 90°C and stir the reaction for 6 hours. Subsequently, cool to room temperature, precipitate the product with methanol, and separate by centrifugation. Finally, vacuum dry the product at 60°C for 12 hours to obtain the desired modified methyl vinyl silicone rubber.

[0102] Secondly, prepare graphene aerogel. Prepare 2 mg / mL graphene oxide aqueous dispersion, add equal mass of L-ascorbic acid, and ultrasonically disperse for 30 minutes. Transfer the mixture to a stainless steel autoclave and hydrothermally react at 170°C for 12 hours. After cooling to room temperature, quick freeze with liquid nitrogen, and then freeze-dry for 48 hours to obtain a density of 10 mg / cm 3 , with a specific surface area of ​​600m 2 / g of graphene aerogel.

[0103] Next, prepare a microencapsulated phase change material. Dissolve 2 parts by weight of chitosan in 100 mL of 2% acetic acid solution, and dissolve 2 parts by weight of sodium alginate in 100 mL of deionized water. Add 20 parts by weight of n-octadecane to the chitosan solution and emulsify at high speed for 10 minutes. Add the emulsion dropwise to the sodium alginate solution and stir for 2 hours to form microcapsules. Cured with 0.5% calcium chloride solution for 1 hour, filtered, and washed with water. Finally, vacuum dried at 60°C for 12 hours to obtain a microencapsulated phase change material with an average particle size of 30 μm and a phase change temperature of 30°C.

[0104] Then, the modified nano magnesium hydroxide was prepared. 100 parts by weight of nano magnesium hydroxide was dispersed in 500 mL of anhydrous ethanol, and 5 parts by weight of γ-glycidyloxypropyltrimethoxysilane was added. The mixture was refluxed and stirred at 80°C for 4 hours, filtered, and washed with ethanol. Finally, vacuum dried at 100°C for 6 hours to obtain a product with an average particle size of 50 nm and a specific surface area of ​​80 m 2 / g of modified nano magnesium hydroxide.

[0105] Again, functionalized carbon nanotubes were prepared. 1 part by weight of multi-walled carbon nanotubes was added to 100 mL of mixed acid (H2SO4:HNO3=3:1, volume ratio), ultrasonically treated for 2 hours, and refluxed at 80°C for 6 hours. After cooling, centrifugation was performed and washed with deionized water until neutral. The product was dispersed in 100 mL of water, 10 parts by weight of urea was added, and hydrothermally reacted at 180°C for 12 hours. After cooling, filtering, washing with water, vacuum drying was performed at 80°C for 12 hours to obtain functionalized carbon nanotubes with an outer diameter of 20 nm, a length of 30 μm, and a nitrogen doping amount of 3 at%.

[0106] Finally, the components prepared above are mixed according to the specified weight parts. First, the modified methyl vinyl silicone rubber and epoxy-modified polysiloxane are added to a vacuum kneader and stirred for 40 minutes at 110°C and 0.5kPa vacuum. Secondly, the temperature is lowered to 80°C, and graphene aerogel, microencapsulated phase change material, and modified nano magnesium hydroxide are added in sequence, and each component is stirred for 15 minutes after addition. Then, functionalized carbon nanotubes, organic modified montmorillonite and zinc borate are added, and mixing is continued for 90 minutes at 0.1kPa vacuum. Again, the mixture is cooled to 85°C, and the platinum catalyst is quickly added under nitrogen protection and stirred for 7 minutes. Finally, the mixture is transferred to a mold preheated to 110°C, hot-pressed at 125°C for 35 minutes under a pressure of 10MPa, and then slowly cooled to room temperature and demolded to obtain the product.

[0107] Preferably, in an embodiment of the present invention, the molded product is vacuum post-cured at 90° C. for 6 hours and then left to stand at room temperature for 48 hours to fully stabilize the material properties.

[0108] Through these four examples, we can see the performance changes of each component under different ratios and preparation conditions. For example, with the increase of the content of modified methyl vinyl silicone rubber, the mechanical strength and toughness of the material are improved. The changes in the density and specific surface area of ​​graphene aerogel affect the thermal insulation and thermal conductivity of the material. The adjustment of the particle size and phase change temperature of the microencapsulated phase change material can optimize the thermal management ability of the material. The changes in the particle size and specific surface area of ​​modified nano magnesium hydroxide affect the flame retardant and mechanical properties of the material. The adjustment of the size and nitrogen doping amount of the functionalized carbon nanotubes can optimize the conductivity and enhancement effect of the material.

[0109] These embodiments fully demonstrate the feasibility and flexibility of the present invention, and provide rich technical references for the practical application of thermal insulation, flame retardant and lightweight silicone rubber for power batteries.

[0110] Comparative Example 1 (corresponding to Example 1)

[0111] This comparative example provides a thermal insulation and flame retardant lightweight silicone rubber for power batteries and a preparation method thereof, the composition of which is the same as that of Example 1, but does not contain graphene aerogel. The specific components (by weight) are: 60 parts of modified methyl vinyl silicone rubber, 10 parts of microencapsulated phase change material, 40 parts of modified nano magnesium hydroxide, 1 part of functionalized carbon nanotubes, 3 parts of organic modified montmorillonite, 5 parts of zinc borate, 2 parts of epoxy modified polysiloxane, and 0.1 parts of platinum catalyst.

[0112] The preparation method of each component is the same as that of Example 1. In the mixing step, since there is no graphene aerogel, the microencapsulated phase change material and the modified nano magnesium hydroxide are directly added. The other preparation steps remain unchanged.

[0113] Through comparative tests, it was found that the sample lacking graphene aerogel was significantly inferior to Example 1 in terms of thermal insulation performance. Its thermal conductivity increased by about 40% to 0.14W / (m·K). This shows that graphene aerogel plays a key role in thermal insulation in the present invention, and its three-dimensional network structure effectively blocks heat transfer. At the same time, due to the lack of the synergistic flame retardant effect of graphene aerogel, the limiting oxygen index (LOI) of the sample was reduced to 32, and the flame retardant performance was significantly reduced.

[0114] Comparative Example 2 (corresponding to Example 2)

[0115] This comparative example provides a thermal insulation and flame retardant lightweight silicone rubber for power batteries and a preparation method thereof, the composition of which is the same as that of Example 2, but the microencapsulated phase change material is replaced by an equal amount of ordinary paraffin. The specific components (by weight) are: 80 parts of modified methyl vinyl silicone rubber, 10 parts of graphene aerogel, 20 parts of paraffin, 50 parts of modified nano magnesium hydroxide, 3 parts of functionalized carbon nanotubes, 5 parts of organic modified montmorillonite, 10 parts of zinc borate, 4 parts of epoxy modified polysiloxane, and 0.3 parts of platinum catalyst.

[0116] Except that the microencapsulated phase change material does not need to be prepared, the preparation method of other components is the same as that of Example 2. In the mixing step, molten paraffin is directly added to replace the microencapsulated phase change material.

[0117] The test results show that the sample using ordinary paraffin wax is obviously inferior to Example 2 in thermal management ability. In the temperature change test simulating the battery working cycle, the surface temperature fluctuation amplitude of the sample of Comparative Example 2 is about 30% higher than that of Example 2. This proves the superiority of microencapsulated phase change materials in stabilizing temperature fluctuations. In addition, due to the lack of protection of microcapsules, paraffin wax easily seeps out at high temperatures, resulting in a decrease in the long-term stability of the material.

[0118] Comparative Example 3 (corresponding to Example 3)

[0119] This comparative example provides a power battery heat-insulating flame-retardant lightweight silicone rubber and its preparation method, the composition of which is the same as that of Example 3, but the modified nano magnesium hydroxide is replaced by unmodified ordinary magnesium hydroxide. The specific components (parts by weight) are: 90 parts of modified methyl vinyl silicone rubber, 12 parts of graphene aerogel, 25 parts of microencapsulated phase change material, 55 parts of ordinary magnesium hydroxide, 4 parts of functionalized carbon nanotubes, 6 parts of organically modified montmorillonite, 12 parts of zinc borate, 5 parts of epoxy-modified polysiloxane, and 0.4 parts of platinum catalyst.

[0120] Except for using unmodified ordinary magnesium hydroxide, the preparation method of other components is the same as that of Example 3. In the mixing step, ordinary magnesium hydroxide powder is directly added.

[0121] The test results show that the sample using unmodified magnesium hydroxide is inferior to Example 3 in both flame retardancy and mechanical properties. Its limiting oxygen index (LOI) is reduced to 34, and the tensile strength is reduced by about 25%. This shows that the modified nano magnesium hydroxide not only improves the flame retardant effect, but also improves the mechanical properties of the material through better compatibility with the silicone rubber matrix. At the same time, unmodified magnesium hydroxide is more easily decomposed at high temperatures, affecting the long-term stability of the material.

[0122] Comparative Example 4 (corresponding to Example 4)

[0123] This comparative example provides a thermal insulation and flame retardant lightweight silicone rubber for power batteries and a preparation method thereof, the composition of which is the same as that of Example 4, but does not contain functionalized carbon nanotubes. The specific components (by weight) are: 100 parts of modified methyl vinyl silicone rubber, 15 parts of graphene aerogel, 30 parts of microencapsulated phase change material, 60 parts of modified nano magnesium hydroxide, 8 parts of organic modified montmorillonite, 15 parts of zinc borate, 6 parts of epoxy modified polysiloxane, and 0.5 parts of platinum catalyst.

[0124] The preparation method of each component is the same as that of Example 4, except that the step of adding the functionalized carbon nanotubes is omitted in the mixing step.

[0125] The test results show that the sample lacking functionalized carbon nanotubes is significantly inferior to Example 4 in terms of conductivity and mechanical strength. Its conductivity is reduced by about two orders of magnitude, which may affect the material's ability to dissipate heat when thermal runaway occurs. At the same time, the material's tensile strength is reduced by about 20% and its elongation at break is reduced by 15%. This demonstrates the important role of functionalized carbon nanotubes in enhancing material properties and providing a conductive network.

[0126] Comparative Example 5 (corresponding to Example 1, but with a different preparation method)

[0127] This comparative example provides a thermal insulation, flame retardant and lightweight silicone rubber for power batteries and a preparation method thereof, the components of which are exactly the same as those in Example 1, but the preparation method is changed. Specifically, in the mixing step, all components are added to a vacuum kneader at once and stirred for 60 minutes at 90°C and a vacuum degree of 0.1 kPa.

[0128] The test results show that the one-time mixed sample is obviously inferior to Example 1 in terms of performance uniformity and component dispersion. The standard deviation of its thermal conductivity increased by about 50%, indicating that the non-uniformity of thermal conductivity increased. At the same time, the mechanical properties of the material also showed a significant decline, with the tensile strength decreasing by about 15% and the elongation at break decreasing by about 10%. This proves that the step-by-step mixing method used in the present invention is crucial to achieving uniform dispersion of the components and giving full play to the synergistic effect.

[0129] Comparative Example 6 (corresponding to Example 2, but with changed post-treatment conditions)

[0130] This comparative example provides a thermal insulation, flame retardant and lightweight silicone rubber for power batteries and a preparation method thereof, the components and main preparation steps of which are exactly the same as those of Example 2, but the post-processing conditions are changed. Specifically, the molded product is directly left at room temperature for 24 hours, and the high-temperature vacuum post-curing step is omitted.

[0131] The test results show that the samples lacking the high temperature vacuum post-curing step are inferior to Example 2 in long-term stability and performance consistency. After 100 thermal cycle tests, the attenuation of the thermal conductivity and mechanical properties of the sample of Comparative Example 6 is about 20% higher than that of Example 2. This shows that the high temperature vacuum post-curing step plays an important role in the full cross-linking and performance stabilization of the material, and is a key process step to achieve a long-life silicone rubber sponge.

[0132] Through these six comparative examples, we can clearly see the importance of each innovation in the present invention. The synergistic effect of key components such as graphene aerogel, microencapsulated phase change material, modified nano magnesium hydroxide and functionalized carbon nanotubes, as well as the carefully designed preparation process, together constitute the core advantages of the present invention. These innovations not only improve the thermal insulation and flame retardant properties of the material, but also significantly improve its mechanical properties, conductivity and long-term stability, providing a high-performance, multifunctional new material solution for power battery safety protection.

[0133] In order to verify the effectiveness of the present invention, a series of test experiments were designed.

[0134] Test Experiment Design:

[0135] 1. Thermal insulation performance test

[0136] Experimental conditions: Use a heat flow tester, the sample size is 100mm×100mm×10mm, the heat source temperature is set to 80℃, and the cold end temperature is 20℃.

[0137] Experimental steps: First, place the sample on the sample holder of the tester. Then, start the heat source and cold source, and record the heat flow value after the temperature stabilizes. Finally, calculate the thermal conductivity according to Fourier's law of heat conduction.

[0138] 2. Flame retardant performance test

[0139] Experimental conditions: The limiting oxygen index method (LOI) was used to test in accordance with ASTM D2863.

[0140] Experimental steps: First, prepare a sample with a size of 150mm×10mm×10mm. Second, place the sample vertically in the test column. Then, adjust the oxygen concentration until the sample can continue to burn for 3 minutes or the burning length reaches 50mm. Finally, record the oxygen concentration at this time as the LOI value.

[0141] 3. Mechanical properties test

[0142] Experimental conditions: A universal testing machine was used to perform tensile tests according to ASTM D412.

[0143] Experimental steps: First, prepare a dumbbell-shaped specimen. Second, fix the specimen on the testing machine fixture. Then, perform a tensile test at a speed of 500 mm / min. Finally, record the tensile strength and elongation at break.

[0144] 4. Conductivity test

[0145] Experimental conditions: The four-probe method was used with a resistivity tester.

[0146] Experimental steps: First, prepare a 50mm×50mm×2mm flat sample. Second, place four probes at equal intervals in contact with the sample surface. Then, apply current through an external power supply. Finally, measure the voltage drop and calculate the conductivity.

[0147] 5. Thermal management capability test

[0148] Experimental conditions: A temperature variation device simulating the battery working cycle was used, with a cycle range of 20-60°C.

[0149] Experimental steps: First, place the sample (100mm×100mm×10mm) on the simulation device. Second, start the temperature cycle program, and each cycle lasts for 1 hour. Then, use an infrared thermal imager to record the temperature change of the sample surface. Finally, calculate the temperature fluctuation amplitude and the latent heat storage capacity of the phase change material.

[0150] 6. Long-term stability test

[0151] Experimental conditions: high temperature aging box, temperature set to 85℃, lasting 1000 hours.

[0152] Experimental steps: First, place the sample in an aging chamber. Second, take out some samples every 200 hours for performance testing. Then, record the changes in various performance indicators. Finally, evaluate the long-term stability of the material.

[0153] The test results are as follows:

[0154] Table 1: Thermal insulation and flame retardant performance test results

[0155] sample Thermal conductivity (W / (m·K)) LOI value (%) Example 1 0.082 36 Example 2 0.078 38 Example 3 0.075 39 Example 4 0.072 40 Comparative Example 1 0.14 32 Comparative Example 2 0.095 35 Comparative Example 3 0.088 34 Comparative Example 4 0.08 37 Comparative Example 5 0.086 35 Comparative Example 6 0.081 36

[0156] Table 2: Mechanical properties and electrical conductivity test results

[0157] sample Tensile strength(MPa) Elongation at break (%) Conductivity (S / m) Example 1 3.8 220 <![CDATA[1.2x10 -4 ]]> Example 2 4.2 235 <![CDATA[1.8x10 -4 ]]> Example 3 4.5 245 <![CDATA[2.3x10 -4 ]]> Example 4 4.8 260 <![CDATA[2.8x10 -4 ]]> Comparative Example 1 3.5 200 <![CDATA[9.0x10 -5 ]]> Comparative Example 2 3.9 225 <![CDATA[1.5x10 -4 ]]> Comparative Example 3 3.4 190 <![CDATA[1.9x10 -4 ]]> Comparative Example 4 3.8 220 <![CDATA[5.0x10 -7 ]]> Comparative Example 5 3.6 210 <![CDATA[1.4x10 -4 ]]> Comparative Example 6 4 230 <![CDATA[1.7x10 -4 ]]>

[0158] Table 3: Thermal management capability and long-term stability test results

[0159] sample Temperature fluctuation range (℃) Latent heat storage capacity (J / g) Performance retention rate after 1000h (%) Example 1 5.2 45 92 Example 2 4.8 52 94 Example 3 4.5 58 95 Example 4 4.2 65 96 Comparative Example 1 7.8 0 88 Comparative Example 2 6.5 30 85 Comparative Example 3 5 55 82 Comparative Example 4 4.6 62 90 Comparative Example 5 5.5 42 89 Comparative Example 6 4.9 50 86

[0160] According to the test results, Example 4 shows the best comprehensive performance and can be regarded as the best embodiment of the present invention.

[0161] In-depth analysis and discussion:

[0162] 1. Thermal insulation performance: The thermal conductivity of Examples 1-4 is significantly lower than that of the comparative examples, especially comparative example 1 (without graphene aerogel). This proves that the three-dimensional network structure of graphene aerogel can effectively block heat transfer and form a "thermal maze" effect. At the same time, as the content of graphene aerogel increases, the thermal insulation performance gradually improves, showing good controllability.

[0163] 2. Flame retardant properties: The LOI values ​​of Examples 1-4 are all higher than those of the comparative example, especially Example 4, which reaches an excellent level of 40%. This is attributed to the synergistic effect of the modified nano-magnesium hydroxide and other components. Nano-magnesium hydroxide decomposes at high temperatures to release water vapor, while graphene aerogel forms a dense carbon layer, which together block oxygen and heat, achieving an extraordinary flame retardant effect.

[0164] 3. Mechanical properties: Examples 1-4 exhibit excellent mechanical properties, especially the tensile strength and elongation at break of Example 4, which are 4.8 MPa and 260%, respectively. This is due to the reinforcing effect of the functionalized carbon nanotubes and the good compatibility of the modified nano magnesium hydroxide with the silicone rubber matrix. The mechanical properties of Comparative Example 3 (unmodified magnesium hydroxide) are significantly poor, highlighting the importance of surface modification.

[0165] 4. Conductivity: The conductivity of Examples 1-4 shows an increasing trend, while the conductivity of Comparative Example 4 (non-functionalized carbon nanotubes) drops by nearly 3 orders of magnitude. This indicates that the functionalized carbon nanotubes form an effective conductive network in the material, which is conducive to rapid heat dissipation during thermal runaway.

[0166] 5. Thermal management capability: Examples 1-4 exhibit excellent temperature control capability, small temperature fluctuations and strong latent heat storage capacity. This is mainly due to the effect of microencapsulated phase change materials. The performance of Comparative Example 2 (using ordinary paraffin) is significantly worse, indicating that microencapsulation technology effectively solves the leakage problem of phase change materials and improves their utilization efficiency.

[0167] 6. Long-term stability: Examples 1-4 still maintain more than 90% of their performance after 1000 hours of high-temperature aging, which is better than all comparative examples. This reflects the synergistic effect between the components of the present invention, especially the addition of modified nano magnesium hydroxide improves the heat resistance of the material, and the encapsulation technology of the microencapsulated phase change material ensures the stability of long-term use.

[0168] Unexpected technical effects:

[0169] 1. Ultra-low thermal conductivity: The thermal conductivity of Example 4 reaches 0.072W / (m·K), which is much lower than that of traditional silicone rubber materials (about 0.2-0.3W / (m·K)). This remarkable thermal insulation effect is due to the unique structure of graphene aerogel and the synergistic effect of other components, forming a multi-scale thermal insulation barrier.

[0170] 2. Excellent balance between flexibility and flame retardancy: Usually, improving the flame retardancy of a material will sacrifice its flexibility. However, the present invention achieves a high LOI value (40%) while still maintaining a high elongation at break of 260%. This is due to the uniform dispersion of nanoscale components and surface modification technology, which achieves a perfect fusion of rigid flame retardants and flexible substrates.

[0171] 3. Adaptive thermal management: Test results show that the material exhibits different thermal conductivity behaviors at different temperatures. This "smart" property stems from the synergistic effect of microencapsulated phase change materials and other components, maintaining heat insulation at low temperatures and promoting heat dissipation at high temperatures, providing all-round thermal protection for power batteries.

[0172] 4. Long-term flame retardant mechanism: Long-term stability tests show that the flame retardant properties of the material are almost unaffected after high-temperature aging. This is because the modified nano-magnesium hydroxide and graphene aerogel form a dynamic flame retardant system, the former continuously releases water vapor, and the latter continuously forms a new carbon layer, ensuring long-term effective flame retardant properties.

[0173] 5. Synergistic electromagnetic shielding effect: Although the present invention is mainly aimed at heat insulation and flame retardancy, the material was unexpectedly found to have good electromagnetic shielding performance during the test. This may be due to the conductive network formed by graphene aerogel and functionalized carbon nanotubes, which not only improves conductivity but also produces a synergistic electromagnetic shielding effect, providing additional protection for the power battery.

[0174] In summary, the present invention not only achieves the expected heat insulation, flame retardancy and lightweight effect through the careful design and synergistic effect of multiple components, but also exhibits excellent comprehensive performance in mechanical properties, electrical conductivity, thermal management ability and long-term stability. This multifunctional integrated material design provides an innovative solution for power battery safety protection and is expected to be widely used in electric vehicles, energy storage systems and other fields.

[0175] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A heat-insulating, flame-retardant, lightweight silicone rubber for power batteries, characterized in that: By weight, it includes the following components: Modified methyl vinyl silicone rubber 60-100 parts; 5-15 parts of graphene aerogel; 10-30 parts of microencapsulated phase change material; 40-60 parts of modified nano magnesium hydroxide; 1-5 parts of functionalized carbon nanotubes; 3-8 parts of organic modified montmorillonite; 5-15 parts of zinc borate; 2-6 parts of epoxy-modified polysiloxane; Platinum catalyst 0.1-0.5 parts.

2. The silicone rubber according to claim 1, characterized in that The preparation method of the modified methyl vinyl silicone rubber comprises the following steps: (1) Add 100 parts by weight of methyl vinyl silicone rubber into a three-necked round-bottom flask; (2) under nitrogen protection, slowly dropwise adding 5-7 parts by weight of phenyl dichlorophosphine; (3) heating to 80-90°C and stirring for 4-6 hours; (4) cooling to room temperature, precipitating the product with methanol, and centrifuging; (5) The product was dried under vacuum at 60°C for 12 hours.

3. The silicone rubber according to claim 1, characterized in that The preparation method of the graphene aerogel comprises the following steps: (1) preparing a 2 mg / mL graphene oxide aqueous dispersion; (2) adding L-ascorbic acid in an amount equal to that of graphene oxide and ultrasonically dispersing for 30 minutes; (3) The mixture was transferred to a stainless steel autoclave and subjected to hydrothermal reaction at 170°C for 12 hours; (4) Cool to room temperature and quick freeze with liquid nitrogen; (5) Freeze-drying for 48 hours to obtain graphene aerogel.

4. The silicone rubber according to claim 1, characterized in that: The preparation method of the microencapsulated phase change material comprises the following steps: (1) Dissolve 2 parts by weight of chitosan in 100 mL of 2% acetic acid solution; (2) Dissolve 2 parts by weight of sodium alginate in 100 mL of deionized water; (3) adding 20 parts by weight of n-octadecane to the chitosan solution and emulsifying at high speed for 10 minutes; (4) adding the emulsion dropwise into the sodium alginate solution and stirring for 2 hours to form microcapsules; (5) solidify with 0.5% calcium chloride solution for 1 hour, filter and wash with water; (6) Vacuum drying at 60°C for 12 hours.

5. The silicone rubber according to claim 1, characterized in that: The preparation method of the modified nano magnesium hydroxide comprises the following steps: (1) Dispersing 100 parts by weight of nano magnesium hydroxide in 500 mL of anhydrous ethanol; (2) adding 3-5 parts by weight of γ-glycidyloxypropyltrimethoxysilane; (3) reflux at 80°C with stirring for 4 hours; (4) filtration and ethanol washing; (5) Vacuum drying at 100°C for 6 hours.

6. The silicone rubber according to claim 1, characterized in that: The method for preparing the functionalized carbon nanotubes comprises the following steps: (1) Add 1 part by weight of multi-walled carbon nanotubes into 100 mL of mixed acid (H2SO4:HNO3=3:1, volume ratio); (2) ultrasonic treatment for 2 hours and reflux at 80°C for 6 hours; (3) cooling, centrifugation, and washing with deionized water until neutral; (4) Dispersing the product in 100 mL of water, adding 10 parts by weight of urea; (5) Hydrothermal reaction at 180°C for 12 hours; (6) Cooling, filtering, and washing; (7) Vacuum drying at 80°C for 12 hours.

7. The silicone rubber according to claim 1, characterized in that: The modified methyl vinyl silicone rubber is a terminal diphenylphosphonyl modified polydimethylsiloxane-polymethyl vinyl siloxane copolymer, the vinyl content of which is 0.15-0.20 mol % and the number average molecular weight is 500,000-600,000 g / mol.

8. The silicone rubber according to claim 1, characterized in that: The graphene aerogel is reduced graphene oxide aerogel, and its density is 5-10 mg / cm 3 , with a specific surface area of ​​400-600m 2 / g; the microencapsulated phase change material is n-octadecane wrapped in chitosan / sodium alginate composite microcapsules, the average particle size of the microcapsules is 20-30μm, and the phase change temperature is 28-30°C; the modified nano magnesium hydroxide is γ-glycidyloxypropyltrimethoxysilane modified nano magnesium hydroxide, the average particle size is 30-50nm, the specific surface area is 60-80m 2 / g; the functionalized carbon nanotubes are carboxylated nitrogen-doped multi-walled carbon nanotubes having an outer diameter of 10-20 nm, a length of 10-30 μm, and a nitrogen doping amount of 2-3 at%.

9. The method for preparing silicone rubber according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) First, add the modified methyl vinyl silicone rubber and epoxy-modified polysiloxane into a vacuum kneader and stir for 30-40 minutes at 90-110° C. and a vacuum degree of 0.1-0.5 kPa; (2) Secondly, cool down to 70-80°C, add graphene aerogel, microencapsulated phase change material, and modified nano magnesium hydroxide in sequence, and stir for 10-15 minutes after each component is added; (3) Then, adding functionalized carbon nanotubes, organic modified montmorillonite and zinc borate, and continuing to mix for 60-90 minutes under a vacuum degree of 0.05-0.1 kPa; (4) Again, the mixture was cooled to 75-85° C., and the platinum catalyst was quickly added under nitrogen protection, and stirred for 3-7 minutes; (5) Finally, the mixture is transferred to a mold preheated to 100-110°C, hot-pressed at 115-125°C for 25-35 minutes under a pressure of 5-10 MPa, then slowly cooled to room temperature and demolded to obtain the product.

10. The preparation method according to claim 9, characterized in that: The method also includes the following post-processing steps: The molded product is vacuum cured at 80-90°C for 4-6 hours and then left to stand at room temperature for 24-48 hours.