A high-voltage polysilazane-based insulating material for new energy vehicle power battery packs and a preparation method thereof

Abstract

The present invention provides a high-voltage polysilazane-based insulating material for new energy vehicle power battery packs and a preparation method thereof, belonging to the technical field of insulating materials. The present invention prepares silicon carbide microspheres by reacting polycarbosilane with polyaniline, and improves their thermal conductivity, electrical insulation and flame retardancy through hydrothermal deposition of molybdenum disulfide and organic boron coating. Secondly, the prepared metal organic supramolecular cage is modified by carbon nitride and surface modification to improve its thermal conductivity, interfacial bonding force and dielectric properties. In addition, carbon nanotubes are treated with acid, modified with rare earth lanthanum and composited with boron nitride to significantly improve their dispersibility, thermal conductivity and insulation properties. The synergistic effect between the various components comprehensively optimizes the thermal, electrical and mechanical properties of the composite material.

Description

Technical Field

[0001] The present invention belongs to the technical field of insulating materials and relates to a high-voltage-resistant polysilazane-based insulating material for a new energy vehicle power battery pack and a preparation method thereof. Background Art

[0002] Against the backdrop of the current global energy transition, new energy vehicles (NEVs), as a key solution for promoting sustainable development and reducing carbon emissions, are experiencing rapid growth. With the rapid growth of the electric vehicle market, the performance and safety of power battery packs, core components of NEVs, have become a focus of industry attention. Power battery packs not only store and release electrical energy but also require stable operation under varying operating conditions. Therefore, selecting the right insulation material to ensure battery safety, durability, and energy conversion efficiency is crucial to improving the overall performance of NEVs.

[0003] Insulating materials play a crucial role in power battery packs. They must not only possess excellent electrical insulation properties to prevent current leakage and short circuits, but also possess good mechanical strength to withstand the stresses of extreme environments such as high voltage and high temperature. Furthermore, insulating materials must be corrosion-resistant to cope with the chemical reactions that may occur during the battery's charge and discharge processes. Polysilazane-based materials have gradually attracted the attention of researchers due to their excellent thermal stability, electrical insulation, and chemical tolerance. These materials not only have excellent thermal stability, maintaining stable performance at high temperatures, but also exhibit excellent electrical insulation properties, making them suitable for high-voltage environments.

[0004] However, despite the significant advantages of polysilazane-based materials, existing polysilazane-based insulating materials still have deficiencies in voltage resistance and mechanical strength, particularly in stability and insulation performance retention in high-temperature, high-voltage environments. This makes traditional polysilazane-based materials unable to meet safety and reliability standards in certain demanding applications, such as the fast-charging technology of future electric vehicles and the high-voltage environments required by high-power battery systems. Therefore, there is an urgent need to develop new, high-performance polysilazane-based insulating materials to address these challenges and provide more reliable protection for the safety and durability of new energy vehicles. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a high-voltage polysilazane-based insulating material for new energy vehicle power battery packs and a preparation method thereof. The present invention prepares silicon carbide microspheres by reacting polycarbosilane with polyaniline, and improves its thermal conductivity, electrical insulation and flame retardancy through hydrothermal deposition of molybdenum disulfide and organic boron coating; secondly, the prepared metal organic supramolecular cage is modified by carbon nitride and surface modification to improve its thermal conductivity, interface bonding force and dielectric properties; in addition, carbon nanotubes are treated with acid, modified with rare earth lanthanum and composited with boron nitride, which significantly improves its dispersibility, thermal conductivity and insulation properties. The synergistic effect between the components comprehensively optimizes the thermal, electrical and mechanical properties of the composite material, providing important support for the development of high-performance insulating materials.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack, the method comprising:

[0008] S11: mixing polycarbosilane and polyaniline, reacting them at a constant temperature under an inert atmosphere, cooling and filtering to obtain a first product, soaking the first product in a mixed acid solution, washing it by centrifugation, and drying it to obtain silicon carbide microspheres;

[0009] S12: dispersing silicon carbide microspheres in deionized water, adding ammonium heptamolybdate and sodium sulfide after ultrasonic dispersion, and then hydrothermally reacting, centrifuging, washing, and drying to obtain a silicon carbide / molybdenum disulfide composite material;

[0010] S13: dissolving a boron trifluoride ether complex and phenyltrimethoxysilane in tetrahydrofuran and stirring to obtain a modified solution, adding the silicon carbide / molybdenum disulfide composite material to obtain a reaction solution A, stirring at a constant temperature and then curing to obtain an organoboron-coated silicon carbide / molybdenum disulfide composite material;

[0011] S21: dissolving trimesic acid and zinc nitrate hexahydrate in a mixed solvent of N,N-dimethylformamide and deionized water, performing a solvothermal reaction, filtering, and washing to obtain a metal organic supramolecular cage;

[0012] S22: calcining melamine to obtain carbon nitride, adding the carbon nitride to concentrated nitric acid for reflux reaction, filtering, washing, and drying to obtain modified carbon nitride, dispersing the modified carbon nitride and the metal organic supramolecular cage in N,N-dimethylformamide, mixing them uniformly, and then performing a solvothermal reaction, filtering, washing, and drying to obtain the carbon nitride-modified metal organic supramolecular cage;

[0013] S23: dispersing the carbon nitride modified metal organic supramolecular cage in anhydrous toluene, adding trifluoropropyltriethoxysilane, reflux reaction, centrifuging, washing, and drying to obtain a pretreated product, and vacuum curing to obtain a composite modified metal organic supramolecular cage;

[0014] S31: modifying carbon nanotubes by stirring in a modifying acid solution to obtain modified carbon nanotubes, dispersing the modified carbon nanotubes in a lanthanum nitrate solution, adding sodium hydroxide to adjust the pH to obtain a reaction solution B, heat-treating the solution under an argon atmosphere, filtering, washing, and drying to obtain lanthanum-modified carbon nanotubes;

[0015] S32: ultrasonically exfoliating hexagonal boron nitride in N-methylpyrrolidone, collecting the supernatant by centrifugation for later use, dispersing lanthanum-modified carbon nanotubes in N-methylpyrrolidone to obtain a first dispersion, mixing the dispersion with the supernatant, and then vacuum filtering, pre-drying, and heat-treating to obtain boron nitride / lanthanum-modified carbon nanotubes;

[0016] S33: dispersing boron nitride / lanthanum modified carbon nanotubes in anhydrous ethanol, adding 3-aminopropyltriethoxysilane and triethylamine, mixing well and reacting at a constant temperature, filtering, washing, pre-drying and then curing to obtain composite modified lanthanum modified carbon nanotubes;

[0017] A1: Disperse polysilazane in anhydrous toluene, and after uniform dispersion, add organic boron-coated silicon carbide / molybdenum disulfide composite materials, composite modified metal organic supramolecular cages, composite modified lanthanum-modified carbon nanotubes, cross-linking agents and flame retardants in sequence, stir to obtain a mixed solution, pour the mixed solution into a mold for degassing, pre-curing, heat curing under an inert atmosphere, and then naturally cool to obtain a high-voltage polysilazane-based insulating material for new energy vehicle power battery packs.

[0018] As a preferred technical solution of the present invention, in S11, the mass ratio of polycarbosilane to polyaniline is 1:(1-1.2), for example, it can be 1:1.00, 1:1.02, 1:1.04, 1:1.06, 1:1.08, 1:1.10, 1:1.12, 1:1.14, 1:1.16, 1:1.18 or 1:1.20, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] In some optional embodiments, the temperature of the isothermal reaction under the inert atmosphere is 1400-1500°C, for example, it can be 1400°C, 1410°C, 1420°C, 1430°C, 1440°C, 1450°C, 1460°C, 1470°C, 1480°C, 1490°C or 1500°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0020] In some optional embodiments, the time of the constant temperature reaction under the inert atmosphere is 2-3 hours, for example, it can be 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] In some optional embodiments, the volume ratio of hydrofluoric acid to nitric acid in the mixed acid solution is (2-3):1, for example, it can be 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1 or 3.0:1, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0022] In some optional embodiments, the mass ratio of the first product to the mixed acid solution is 1:(20-30), for example, it can be 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, 1:26, 1:27, 1:28, 1:29 or 1:30, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0023] In some optional embodiments, the first product is immersed in the mixed acid solution for 4-6 hours, for example, 4.0 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours, 5.0 hours, 5.2 hours, 5.4 hours, 5.6 hours, 5.8 hours or 6.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] As a preferred technical solution of the present invention, in S12, the mass fraction of the silicon carbide microspheres in deionized water is 0.8-1.2 wt.%, for example, it can be 0.80%, 0.84%, 0.88%, 0.92%, 0.96%, 1.00%, 1.04%, 1.08%, 1.12%, 1.16% or 1.20%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] In some optional embodiments, the molar ratio of ammonium heptamolybdate to sodium sulfide is 1:(2-3), for example, it can be 1:2.0, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9 or 1:3.0, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0026] In some optional embodiments, the mass ratio of silicon carbide to ammonium heptamolybdate is 1:(0.2-0.3), for example, it can be 1:0.20, 1:0.21, 1:0.22, 1:0.23, 1:0.24, 1:0.25, 1:0.26, 1:0.27, 1:0.28, 1:0.29 or 1:0.30, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0027] In some optional embodiments, the temperature of the hydrothermal reaction is 170-180°C, for example, it can be 170°C, 171°C, 172°C, 173°C, 174°C, 175°C, 176°C, 177°C, 178°C, 179°C or 180°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0028] In some optional embodiments, the hydrothermal reaction time is 10-14 h, for example, it can be 10.0 h, 10.4 h, 10.8 h, 11.2 h, 11.6 h, 12.0 h, 12.4 h, 12.8 h, 13.2 h, 13.6 h or 14.0 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] As a preferred technical solution of the present invention, in S13, the molar ratio of the boron trifluoride ether complex to phenyltrimethoxysilane is (0.8-1.2):1, for example, it can be 0.80:1, 0.84:1, 0.88:1, 0.92:1, 0.96:1, 1.00:1, 1.04:1, 1.08:1, 1.12:1, 1.16:1 or 1.20:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] In some optional embodiments, the total mass fraction of boron trifluoride ether complex and phenyltrimethoxysilane in the modified solution is 5-8 wt.%, for example, it can be 5.0%, 5.3%, 5.6%, 5.9%, 6.2%, 6.5%, 6.8%, 7.1%, 7.4%, 7.7% or 8.0%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0031] In some optional embodiments, the solid-liquid mass ratio of the silicon carbide / molybdenum disulfide composite material to the modified solution is 1:(15-25), for example, it can be 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23, 1:24 or 1:25, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0032] In some optional embodiments, the temperature of the constant temperature stirring of the reaction liquid A is 60-70°C, for example, it can be 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C or 70°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0033] In some optional embodiments, the constant temperature stirring time of the reaction liquid A is 5-7h, for example, it can be 5.0h, 5.2h, 5.4h, 5.6h, 5.8h, 6.0h, 6.2h, 6.4h, 6.6h, 6.8h or 7.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] In some optional embodiments, the curing temperature is 250-280°C, for example, it can be 250°C, 253°C, 256°C, 259°C, 262°C, 265°C, 268°C, 271°C, 274°C, 277°C or 280°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] In some optional embodiments, the curing time is 1.5-2.5h, for example, it can be 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2.0h, 2.1h, 2.2h, 2.3h, 2.4h or 2.5h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] As a preferred technical solution of the present invention, in S21, the molar ratio of trimesic acid to zinc nitrate hexahydrate is 1:(1-2), for example, it can be 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2.0, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] In some optional embodiments, the volume ratio of N,N-dimethylformamide to deionized water in the mixed solvent is (4-5):1, for example, it can be 4.0:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1, 4.5:1, 4.6:1, 4.7:1, 4.8:1, 4.9:1 or 5.0:1, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0038] In some optional embodiments, the total concentration of trimesic acid and zinc nitrate hexahydrate in the mixed solvent is 0.05-0.1 M, for example, it can be 0.050 M, 0.055 M, 0.060 M, 0.065 M, 0.070 M, 0.075 M, 0.080 M, 0.085 M, 0.090 M, 0.095 M or 0.100 M, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] In some optional embodiments, the temperature of the solvent thermal reaction is 110-130°C, for example, it can be 110°C, 112°C, 114°C, 116°C, 118°C, 120°C, 122°C, 124°C, 126°C, 128°C or 130°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0040] In some optional embodiments, the solvent thermal reaction time is 45-50h, for example, it can be 45.0h, 45.5h, 46.0h, 46.5h, 47.0h, 47.5h, 48.0h, 48.5h, 49.0h, 49.5h or 50.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] As a preferred technical solution of the present invention, in S22, the temperature of calcining melamine is 530-580°C, for example, it can be 530°C, 535°C, 540°C, 545°C, 550°C, 555°C, 560°C, 565°C, 570°C, 575°C or 580°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0042] In some optional embodiments, the melamine calcination time is 3-5h, for example, it can be 3.0h, 3.2h, 3.4h, 3.6h, 3.8h, 4.0h, 4.2h, 4.4h, 4.6h, 4.8h or 5.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] In some optional embodiments, the mass fraction of the carbon nitride in concentrated nitric acid is 2-5 wt.%, for example, it can be 2.0%, 2.3%, 2.6%, 2.9%, 3.2%, 3.5%, 3.8%, 4.1%, 4.4%, 4.7% or 5.0%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0044] In some optional embodiments, the temperature of the reflux reaction is 120-130°C, for example, it can be 120°C, 121°C, 122°C, 123°C, 124°C, 125°C, 126°C, 127°C, 128°C, 129°C or 130°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0045] In some optional embodiments, the reflux reaction time is 7-9h, for example, it can be 7.0h, 7.2h, 7.4h, 7.6h, 7.8h, 8.0h, 8.2h, 8.4h, 8.6h, 8.8h or 9.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] In some optional embodiments, the mass ratio of the modified carbon nitride to the metal organic supramolecular cage is (0.8-1.2):1, for example, it can be 0.80:1, 0.84:1, 0.88:1, 0.92:1, 0.96:1, 1.00:1, 1.04:1, 1.08:1, 1.12:1, 1.16:1 or 1.20:1, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0047] In some optional embodiments, the mass fraction of the modified carbon nitride in N,N-dimethylformamide is 1-2 wt.%, for example, it can be 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9% or 2.0%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0048] In some optional embodiments, the temperature of the solvent thermal reaction is 130-150°C, for example, it can be 130°C, 132°C, 134°C, 136°C, 138°C, 140°C, 142°C, 144°C, 146°C, 148°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0049] In some optional embodiments, the solvent thermal reaction time is 10-14h, for example, it can be 10.0h, 10.4h, 10.8h, 11.2h, 11.6h, 12.0h, 12.4h, 12.8h, 13.2h, 13.6h or 14.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0050] As a preferred technical solution of the present invention, in S23, the mass fraction of the carbon nitride-modified metal organic supramolecular cage in anhydrous toluene is 1-2 wt.%, for example, it can be 1.0 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, 1.5 wt.%, 1.6 wt.%, 1.7 wt.%, 1.8 wt.%, 1.9 wt.% or 2.0 wt.%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0051] In some optional embodiments, the feeding amount of the trifluoropropyltriethoxysilane is 4-6% of the mass of the carbon nitride modified metal organic supramolecular cage, for example, it can be 4.0%, 4.2%, 4.4%, 4.6%, 4.8%, 5.0%, 5.2%, 5.4%, 5.6%, 5.8% or 6.0%, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0052] In some optional embodiments, the temperature of the reflux reaction is 115-125°C, for example, it can be 115°C, 116°C, 117°C, 118°C, 119°C, 120°C, 121°C, 122°C, 123°C, 124°C or 125°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0053] In some optional embodiments, the reflux reaction time is 5-7h, for example, it can be 5.0h, 5.2h, 5.4h, 5.6h, 5.8h, 6.0h, 6.2h, 6.4h, 6.6h, 6.8h or 7.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0054] In some optional embodiments, the vacuum curing temperature is 120-140°C, for example, it can be 120°C, 122°C, 124°C, 126°C, 128°C, 130°C, 132°C, 134°C, 136°C, 138°C or 140°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0055] In some optional embodiments, the vacuum curing time is 1.5-2.5h, for example, it can be 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2.0h, 2.1h, 2.2h, 2.3h, 2.4h or 2.5h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] As a preferred technical solution of the present invention, in S31, the volume ratio of concentrated sulfuric acid to concentrated nitric acid in the modified acid solution is (3-4):1, for example, it can be 3.0:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1 or 4.0:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0057] In some optional embodiments, the mass ratio of the carbon nanotubes to the modified acid solution is 1:(20-30), for example, it can be 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, 1:26, 1:27, 1:28, 1:29 or 1:30, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0058] In some optional embodiments, the temperature for stirring and modifying the carbon nanotubes in the modified acid solution is 80-90°C, for example, it can be 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C or 90°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0059] In some optional embodiments, the carbon nanotubes are stirred and modified in the modified acid solution for 5-7 hours, for example, 5.0 hours, 5.2 hours, 5.4 hours, 5.6 hours, 5.8 hours, 6.0 hours, 6.2 hours, 6.4 hours, 6.6 hours, 6.8 hours or 7.0 hours, but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0060] In some optional embodiments, the concentration of the lanthanum nitrate solution is 0.1-0.2M, for example, it can be 0.10M, 0.11M, 0.12M, 0.13M, 0.14M, 0.15M, 0.16M, 0.17M, 0.18M, ​​0.19M or 0.20M, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0061] In some optional embodiments, the mass ratio of the lanthanum nitrate to the modified carbon nanotubes is 1:(8-12), for example, it can be 1:8.0, 1:8.4, 1:8.8, 1:9.2, 1:9.6, 1:10.0, 1:10.4, 1:10.8, 1:11.2, 1:11.6 or 1:12.0, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0062] In some optional embodiments, sodium hydroxide is added to adjust the pH to 8-9, for example, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9 or 9.0, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0063] In some optional embodiments, the temperature of the heat treatment of the reaction liquid B under an argon atmosphere is 480-520°C, for example, it can be 480°C, 484°C, 488°C, 492°C, 496°C, 500°C, 504°C, 508°C, 512°C, 516°C or 520°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0064] In some optional embodiments, the heat treatment time of the reaction liquid B under an argon atmosphere is 1-2 h, for example, it can be 1.0 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h or 2.0 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0065] As a preferred technical solution of the present invention, in S32, the concentration of hexagonal boron nitride in N-methylpyrrolidone is 0.5-1 mg / mL, for example, it can be 0.50 mg / mL, 0.55 mg / mL, 0.60 mg / mL, 0.65 mg / mL, 0.70 mg / mL, 0.75 mg / mL, 0.80 mg / mL, 0.85 mg / mL, 0.90 mg / mL, 0.95 mg / mL or 1.00 mg / mL, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0066] In some optional embodiments, the concentration of lanthanum-modified carbon nanotubes in the first dispersion is 1-2 mg / mL, for example, 1.0 mg / mL, 1.1 mg / mL, 1.2 mg / mL, 1.3 mg / mL, 1.4 mg / mL, 1.5 mg / mL, 1.6 mg / mL, 1.7 mg / mL, 1.8 mg / mL, 1.9 mg / mL or 2.0 mg / mL, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0067] In some optional embodiments, the mass ratio of the first dispersion and the supernatant is (1.2-1.8):1, for example, it can be 1.20:1, 1.26:1, 1.32:1, 1.38:1, 1.44:1, 1.50:1, 1.56:1, 1.62:1, 1.68:1, 1.74:1 or 1.80:1, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0068] In some optional embodiments, the mixing reaction time is 2-3h, for example, it can be 2.0h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0069] In some optional embodiments, the pre-drying temperature is 70-80°C, for example, it can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0070] In some optional embodiments, the pre-drying time is 3-4h, for example, it can be 3.0h, 3.1h, 3.2h, 3.3h, 3.4h, 3.5h, 3.6h, 3.7h, 3.8h, 3.9h or 4.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0071] In some optional embodiments, the temperature of the heat treatment is 280-320°C, for example, it can be 280°C, 284°C, 288°C, 292°C, 296°C, 300°C, 304°C, 308°C, 312°C, 316°C or 320°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0072] In some optional embodiments, the heat treatment time is 25-35 min, for example, it can be 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, 31 min, 32 min, 33 min, 34 min or 35 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0073] As a preferred technical solution of the present invention, in S33, the mass fraction of the boron nitride / lanthanum modified carbon nanotubes in anhydrous ethanol is 2-3wt.%, for example, it can be 2.0wt.%, 2.1wt.%, 2.2wt.%, 2.3wt.%, 2.4wt.%, 2.5wt.%, 2.6wt.%, 2.7wt.%, 2.8wt.%, 2.9wt.% or 3.0wt.%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0074] In some optional embodiments, the feeding amount of the 3-aminopropyltriethoxysilane is 4-6% of the mass of the boron nitride / lanthanum modified carbon nanotubes, for example, it can be 4.0%, 4.2%, 4.4%, 4.6%, 4.8%, 5.0%, 5.2%, 5.4%, 5.6%, 5.8% or 6.0%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0075] In some optional embodiments, the feeding amount of the triethylamine is 0.5-1% of the mass of the boron nitride / lanthanum modified carbon nanotubes, for example, it can be 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%, 0.80%, 0.85%, 0.90%, 0.95% or 1.00%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0076] In some optional embodiments, the temperature of the isothermal reaction is 50-60°C, for example, it can be 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0077] In some optional embodiments, the isothermal reaction time is 2-3h, for example, it can be 2.0h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0078] In some optional embodiments, the pre-drying temperature is 70-80°C, for example, it can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0079] In some optional embodiments, the pre-drying time is 2-3h, for example, it can be 2.0h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0080] In some optional embodiments, the curing temperature is 140-150°C, for example, it can be 140°C, 141°C, 142°C, 143°C, 144°C, 145°C, 146°C, 147°C, 148°C, 149°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0081] In some optional embodiments, the curing time is 2-3h, for example, it can be 2.0h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0082] As a preferred technical solution of the present invention, in A1, the mass fraction of the polysilazane in anhydrous toluene is 20-25 wt.%, for example, it can be 20.0 wt.%, 20.5 wt.%, 21.0 wt.%, 21.5 wt.%, 22.0 wt.%, 22.5 wt.%, 23.0 wt.%, 23.5 wt.%, 24.0 wt.%, 24.5 wt.% or 25.0 wt.%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0083] In some optional embodiments, the pre-curing temperature is 70-80°C, for example, it can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0084] In some optional embodiments, the pre-curing time is 3-4h, for example, it can be 3.0h, 3.1h, 3.2h, 3.3h, 3.4h, 3.5h, 3.6h, 3.7h, 3.8h, 3.9h or 4.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0085] In some optional embodiments, the temperature of thermal curing under an inert atmosphere is 200-250°C, for example, it can be 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C or 250°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0086] In some optional embodiments, the time for thermal curing under an inert atmosphere is 2-3 hours, for example, it can be 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0087] In a second aspect, the present invention provides a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack. The high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack includes polysilazane, an organic boron-coated silicon carbide / molybdenum disulfide composite material, a composite modified metal organic supramolecular cage, a composite modified lanthanum-modified carbon nanotube, a cross-linking agent, and a flame retardant; the mass ratio of polysilazane, organic boron-coated silicon carbide / molybdenum disulfide composite material, composite modified metal organic supramolecular cage, composite modified lanthanum-modified carbon nanotube, cross-linking agent, and flame retardant in the high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack is: (80-85): (30-40): (35-45): (25-35): (4-5): (3-4).

[0088] The crosslinking agent is any one of vinyltrimethoxysilane, vinyltriethoxysilane or γ-methacryloxypropyltrimethoxysilane or a combination of two;

[0089] The flame retardant is any one of aluminum hydroxide, magnesium hydroxide or ammonium polyphosphate or a combination of two thereof.

[0090] The present invention prepares silicon carbide microspheres by reacting polycarbosilane with polyaniline at high temperature under an inert atmosphere. Polycarbosilane, as an important organosilicon polymer, decomposes into silicon carbide nanocrystals during a high-temperature cracking process, providing the main silicon source for silicon carbide. Polyaniline, as a conjugated polymer material with good conductivity, decomposes into a carbon source under high-temperature reaction conditions. The decomposition products released at the same time (such as ammonia or nitrogen oxides) can play a certain auxiliary role in the reaction system, reducing the surface energy during the cracking process and promoting the uniform nucleation and growth of silicon carbide microspheres. This design ensures the uniformity of the particle size and surface smoothness of the product, and further optimizes the morphology and physical properties of the silicon carbide microspheres.

[0091] Silicon carbide is a typical high-performance ceramic material with a range of excellent physical and chemical properties. First, silicon carbide has excellent electrical insulation properties, and its high electrical breakdown strength makes it very suitable for use as a high-voltage insulation material. Second, its high thermal conductivity enables it to effectively dissipate heat, reducing the risk of heat accumulation in the material. In addition, silicon carbide also has extremely high mechanical strength and hardness, which can significantly improve the mechanical properties of composite materials. These properties make silicon carbide an ideal filler for high-performance insulating composite materials, especially in applications such as new energy vehicle power battery packs, where electrical and thermal performance requirements are stringent.

[0092] However, unmodified silicon carbide has shown some shortcomings in practical applications. First, the surface chemical inertness of silicon carbide is high and lacks active functional groups, resulting in weak interfacial bonding between it and the polymer matrix (such as polysilazane). This weak interfacial effect may cause interfacial delamination or stress concentration when the composite material is stressed or heated, significantly reducing the mechanical strength and electrical properties of the composite material. Secondly, due to the large specific surface area and high surface energy of silicon carbide microspheres, they are prone to agglomeration in the polymer matrix, which makes the filler dispersion worse, and ultimately leads to uneven performance of the composite material, such as deviations in local thermal conductivity or dielectric properties.

[0093] Therefore, the present invention modifies the silicon carbide microspheres by growing molybdenum disulfide on the surface. Molybdenum disulfide is a typical two-dimensional layered transition metal sulfide, which is widely used in the research and development of functional materials due to its unique crystal structure and physical and chemical properties. In particular, the layered structure of molybdenum disulfide is composed of a three-layer atomic stack of sulfur-molybdenum-sulfur bound by weak van der Waals forces, with ultra-thin two-dimensional characteristics and excellent lubricity. Molybdenum disulfide not only has high thermal conductivity, but also has a large specific surface area and abundant surface active sites. These characteristics make it suitable as a functional coating for silicon carbide surface modification.

[0094] In this invention, molybdenum disulfide nanosheets are uniformly deposited on the surface of silicon carbide microspheres through a hydrothermal reaction, creating a silicon carbide / molybdenum disulfide composite with a core-shell structure. The hydrothermal reaction provides a high-temperature, high-pressure reaction environment, which promotes the reaction of ammonium heptamolybdate and sodium sulfide on the silicon carbide surface to form molybdenum disulfide nanosheets. Because the molybdenum disulfide produced under hydrothermal conditions has good crystallinity, the nanosheets firmly adhere to the silicon carbide surface through chemical adsorption or physical bonding, ensuring the stability and uniformity of the composite.

[0095] This core-shell structure design significantly enhances the performance of silicon carbide. First, the introduction of molybdenum disulfide effectively improves the thermal conductivity of silicon carbide. This is because molybdenum disulfide itself has a high lateral thermal conductivity, and its layered structure can provide an additional conduction path for heat transfer. Secondly, the layered structure of molybdenum disulfide brings abundant surface active sites, including sulfur bonds and possible defective active sites, which improves the surface activity of silicon carbide and provides more binding sites for subsequent surface functionalization treatments. In addition, the layered characteristics of molybdenum disulfide also have a good lubricating effect, which has a positive impact on the processing performance of the material and the interface stability of the composite material.

[0096] On this basis, the silicon carbide / molybdenum disulfide composite material was further subjected to an organic boron surface coating treatment to further improve its interface compatibility, electrical insulation and flame retardancy. Specifically, a stable organic boron coating layer was formed by co-acting boron trifluoride etherate complex and phenyltrimethoxysilane on the surface of the silicon carbide / molybdenum disulfide composite material. Boron trifluoride etherate complex can chemically react with the active sites exposed on the surface of molybdenum disulfide to generate stable chemical bonds. At the same time, phenyltrimethoxysilane forms a silicon-oxygen network on the surface of the material through a hydrolysis and condensation reaction, and its phenyl structure can effectively enhance the hydrophobicity of the material, thereby improving the dispersibility and interface compatibility of the composite material in the polysilazane matrix.

[0097] The organoboron coating enhances multiple functional properties in the composite material. First, the introduction of boron-oxygen bonds enhances the material's electrical insulation and reduces dielectric loss, thereby improving the composite's voltage resistance. Second, the presence of the organoboron layer significantly improves the material's flame retardancy. This is because boron can participate in charring and flame retardant reactions under high temperature conditions, inhibiting the material's combustion behavior. Furthermore, the chemical stability and hydrophobicity of the organoboron coating further enhance the long-term stability of the composite material in complex operating environments.

[0098] The present invention synthesizes a metal-organic supramolecular cage by using trimesic acid and zinc nitrate under solvent thermal reaction conditions, providing a functionalized porous material foundation for the development of high-performance insulating materials. Metal-organic supramolecular cages are a type of porous material formed by the combination of organic ligands and metal ions through coordination bonds, with a highly designable, controllable microstructure and excellent physical and chemical properties. In the present invention, trimesic acid is used as a ligand, and its tricarboxyl structure provides multiple coordination sites for metal ions, which can form a stable three-dimensional pore structure through coordination. Through solvent thermal reaction conditions, the crystal structure of the metal-organic supramolecular cage can be precisely controlled, and ultimately a metal-organic supramolecular cage with a high specific surface area and highly ordered pores is prepared.

[0099] Metal-organic supramolecular cages exhibit significant performance advantages in composite materials. First, their high specific surface area and porous structure provide more contact sites for interface regulation in composite materials, significantly improving the dielectric properties of composite materials. Second, their excellent chemical and thermal stability enable them to maintain structural integrity under high temperatures and complex environments, ensuring the long-term performance of composite materials. In addition, the porous structure of metal-organic supramolecular cages can effectively reduce the dielectric loss of the material, thereby improving the voltage resistance of the composite material. These advantages make metal-organic supramolecular cages an important functional filler in the design of high-performance insulating materials.

[0100] However, unmodified metal-organic supramolecular cages still have some shortcomings in practical applications. First, the mechanical properties of metal-organic supramolecular cages are weak, and their framework structure is prone to local damage when subjected to external force or thermal stress, which may lead to a decrease in the mechanical properties of the composite material; secondly, due to the weak bonding force between the surface chemical structure of the metal-organic supramolecular cage and the polymer matrix (such as polysilazane), the interface compatibility is poor. This interface defect may cause stress concentration or interface delamination, affecting the overall performance of the composite material. In addition, the thermal conductivity of metal-organic supramolecular cages is generally low, which makes it difficult to meet the requirements of high thermal conductivity insulating materials, especially in applications such as new energy vehicle power battery packs that have strict requirements on thermal management capabilities.

[0101] In order to solve these problems, the present invention designs a series of targeted modification steps to functionalize the metal organic supramolecular cage by introducing carbon nitride. Carbon nitride is a two-dimensional material with high thermal conductivity, chemical stability and excellent surface activity. Its layered structure enables it to form a stable composite structure with the surface of the metal organic supramolecular cage. In the present invention, active functional groups such as carboxyl and hydroxyl groups are introduced on its surface by treating carbon nitride with concentrated nitric acid. These functional groups can chemically react with the ligand structure of the metal organic supramolecular cage, and carbon nitride is loaded on the surface of the metal organic supramolecular cage through the action of covalent bonds or hydrogen bonds to form a stable metal organic supramolecular cage / carbon nitride composite structure.

[0102] The introduction of carbon nitride is of great significance to the performance improvement of metal-organic supramolecular cages. First, the high thermal conductivity of carbon nitride significantly enhances the overall thermal conductivity of the metal-organic supramolecular cage, providing a more efficient heat conduction path for the composite material. Second, the high mechanical strength and flexibility of carbon nitride effectively enhance the mechanical properties of the metal-organic supramolecular cage, enabling it to better withstand external stress in the composite material. In addition, the composite structure formed by carbon nitride and the surface of the metal-organic supramolecular cage significantly improves the interfacial bonding between the two, reduces the problem of interface defects, and thus improves the overall performance of the composite material.

[0103] On the basis of carbon nitride modification, the present invention further introduces a silicon-oxygen network structure on the surface of the metal organic supramolecular cage through the hydrolysis and polycondensation reaction of trifluoropropyltriethoxysilane. Trifluoropropyltriethoxysilane is a fluorine-containing silane coupling agent. Its hydrolysis and polycondensation reaction can form stable silicon-oxygen bonds on the surface of the material. At the same time, its trifluoropropyl structure can significantly reduce the surface energy of the material, enhancing the hydrophobicity and chemical stability of the composite material. Through this step, the surface of the metal organic supramolecular cage is not only further functionalized, but also significantly improves the dispersibility and interfacial compatibility of the material in the polysilazane matrix.

[0104] The present invention introduces carbon nanotubes as functional fillers to significantly improve the mechanical properties, thermal conductivity and toughening effect of the composite material. Carbon nanotubes are a nanomaterial with a hollow tubular structure. Their unique physical and chemical properties make them show great potential in various high-performance composite materials. First, carbon nanotubes have high strength and modulus, which can improve the mechanical properties of composite materials, especially in the matrix, they can effectively resist the effects of external stress; secondly, carbon nanotubes have high thermal conductivity and can form efficient heat conduction channels in the composite material, thereby improving the thermal management ability of the material. In addition, due to the high aspect ratio of carbon nanotubes, they can form a uniformly distributed network structure in the matrix, which plays a significant toughening role, effectively improving the toughness of the composite material and reducing the risk of brittle fracture.

[0105] However, unmodified carbon nanotubes face many problems in practical applications, which limits their widespread application in the field of composite materials. First, the surface chemical inertness of carbon nanotubes is strong and lacks active functional groups, which makes it difficult to form a firm interface bond in a polymer matrix (such as polysilazane), thereby affecting the interface strength and overall performance of the composite material. Secondly, because the carbon nanotube surface has a higher van der Waals force, it is easy to agglomerate in the matrix, and is difficult to achieve uniform dispersion, resulting in the local inhomogeneity of filler distribution, thereby weakening the performance of the composite material. In addition, although the high electrical conductivity of carbon nanotubes is a kind of advantage in conductive composite materials, it may cause dielectric properties to decline in high-insulation materials, reducing the breakdown voltage and electrical insulation performance of the material. Therefore, in order to solve these key problems, the present invention has carried out multi-step modification treatment to carbon nanotubes to give them higher surface activity, more excellent interface bonding force and the performance that is more suitable for insulating material applications.

[0106] First, the surface of the carbon nanotubes is initially activated by acid treatment. The acid treatment uses a mixed acid system of concentrated nitric acid and sulfuric acid, and utilizes the oxidizing effect of the strong acid to introduce active functional groups such as hydroxyl and carboxyl groups on the surface of the carbon nanotubes. During the acid treatment process, the oxidant can destroy part of the π bond structure of the carbon nanotubes, forming polar functional groups on the tube wall and tube ends. These functional groups significantly improve the surface hydrophilicity and chemical activity of the carbon nanotubes, thereby effectively improving their dispersibility in the matrix, while providing more binding points for subsequent chemical modification. The activated carbon nanotubes can not only be more evenly distributed in the polysilazane matrix, but also significantly improve the interfacial bonding strength with the matrix through the surface polarity.

[0107] To further enhance the insulation and thermal stability of carbon nanotubes, the present invention introduces rare earth lanthanum ions to modify them, building upon the acid treatment. Lanthanum ions react with carboxyl and hydroxyl groups introduced onto the carbon nanotube surface to form a stable rare earth oxide-modified layer. The introduction of lanthanum ions optimizes carbon nanotube performance in multiple ways. On the one hand, the rare earth oxide layer shields the carbon nanotubes, significantly reducing their electrical conductivity and thereby improving the composite material's withstand voltage and electrical insulation. On the other hand, the high thermal stability of lanthanum ions imparts enhanced high-temperature resistance to the carbon nanotubes, enabling them to maintain structural and performance stability in high-temperature environments. Furthermore, the rare earth-modified layer further enhances the interfacial forces between the carbon nanotubes and the substrate, laying the foundation for subsequent composite modification.

[0108] In order to further improve the thermal conductivity and electrical insulation of carbon nanotubes, the present invention introduces boron nitride to carry out composite modification of lanthanum-modified carbon nanotubes. Boron nitride is a two-dimensional material with high thermal conductivity and high insulation. Its layered structure consists of nitrogen-boron planes bound by strong covalent bonds and interlayer interactions bound by weak van der Waals forces. After exfoliation treatment, boron nitride forms a single layer or a few-layer structure, which can be uniformly attached to the surface of lanthanum-modified carbon nanotubes through electrostatic adsorption or chemical bonding. The introduction of boron nitride is of great significance in improving material performance. On the one hand, the high thermal conductivity of boron nitride significantly enhances the thermal conductivity of carbon nanotubes, and can construct a multidimensional thermal conductive network in the composite material, thereby significantly improving the overall thermal conductivity of the composite material; on the other hand, the high insulation of boron nitride effectively reduces the electrical conductivity of the composite material, further improving its electrical breakdown strength and voltage resistance. In addition, the two-dimensional structure of boron nitride can also enhance the interface stability of the composite material and reduce interface defects.

[0109] Finally, in order to optimize the dispersibility and interface bonding performance of carbon nanotubes in polysilazane matrix, the present invention adopts 3-aminopropyl triethoxysilane to carry out surface modification to boron nitride composite carbon nanotubes. The ethoxy group of 3-aminopropyl triethoxysilane can generate silanol after hydrolysis, forms a silicon oxygen network on the surface of carbon nanotube by polycondensation reaction, and its amino group can produce chemical bond or hydrogen bond with the silicon or nitrogen atom in polysilazane matrix. By the modification treatment of 3-aminopropyl triethoxysilane, the interface bonding force of carbon nanotube and matrix is ​​significantly improved, and interface compatibility is further enhanced, and the dispersibility of material in matrix is ​​optimized, and the agglomeration phenomenon of filler is avoided. In addition, silane modification also improves the processing performance of composite material, so that its mechanical property and thermal stability are fully optimized.

[0110] At the same time, there is a synergistic enhancement effect in the system: silicon carbide itself has high thermal conductivity, but its thermal conduction path mainly depends on the point contact between filler particles, and the thermal conductivity efficiency is limited. Molybdenum disulfide, as a two-dimensional layered material, has good thermal conductivity between its layers and provides a large lateral thermal conduction path. When molybdenum disulfide is uniformly deposited on the surface of silicon carbide by a hydrothermal method, a core-shell structure is formed, which not only improves the thermal conductivity efficiency of silicon carbide, but also significantly enhances the overall thermal conductivity of the composite material through the thermal conduction network of the layered structure; secondly, the surface of silicon carbide itself is chemically inert and has weak bonding with the matrix. The introduction of molybdenum disulfide provides more surface active sites (such as sulfur groups and defect sites) through its layered nanosheets. These sites can serve as binding points for subsequent surface modifications, thereby improving the dispersion of silicon carbide in the matrix and the interfacial bonding strength.

[0111] The synergistic effect between the silicon carbide / molybdenum disulfide composite and the organoboron coating is as follows: silicon carbide and molybdenum disulfide themselves have good insulation properties, but after being coated with organoboron, the high resistivity of the boron oxide layer further blocks possible charge conduction paths, significantly reducing the dielectric loss of the composite. Therefore, the combination of silicon carbide / molybdenum disulfide and the organoboron coating improves the composite's voltage resistance, making it more suitable for insulation applications in high electric field environments. Secondly, the boron element in the organoboron coating can participate in carbonization and flame retardant reactions under high temperature conditions, forming a stable carbonized layer that can effectively inhibit flame propagation. At the same time, the physical barrier effect of the molybdenum disulfide layer further enhances the material's flame retardancy, and the two form a synergistic flame retardant effect in high temperature environments. In addition, the organoboron coating is chemically bonded to the molybdenum disulfide surface, which not only improves the surface stability of the composite but also enhances the composite's chemical resistance in extreme environments (such as moisture, high temperature, or acidic and alkaline environments).

[0112] The synergistic enhancement effect of MOSCs and carbon nitride is as follows: The porous structure of MOSCs typically limits their thermal conductivity, but by modifying their surfaces with carbon nitride, the high thermal conductivity of this two-dimensional material can compensate for the MOSC's inherent thermal conductivity deficit. The thermal conductivity pathways formed by carbon nitride, combined with the porous structure of the MOSCs, significantly enhance the overall thermal conductivity of the composite. While the unmodified MOSCs have weak surface adhesion to the matrix, carbon nitride, treated with concentrated nitric acid, introduces carboxyl and hydroxyl groups onto its surface. These functional groups react chemically with the MOSC ligands, forming a stable interfacial bond. Furthermore, the layered structure of carbon nitride mitigates interfacial stress concentration, further enhancing interfacial adhesion. MOSCs have excellent insulating properties, but their porous structure can lead to localized electric field enhancement. The high insulating properties of carbon nitride mitigate this phenomenon and, by forming a uniform coating on the MOSC surface, further enhance the composite's electrical breakdown strength and dielectric stability.

[0113] The combination of carbon nanotubes and metal-organic supramolecular cages has a synergistic effect by enhancing the mechanical and interfacial properties of the composite material: the high strength and high modulus of the carbon nanotubes can enhance the overall mechanical properties of the composite material, while the porous structure of the metal-organic supramolecular cages acts as a buffer by absorbing stress. The combination of the two gives the composite material both high strength and high toughness; the porous structure of the metal-organic supramolecular cages provides more binding sites for the carbon nanotubes, and the high aspect ratio of the carbon nanotubes helps to form a continuous filler network in the matrix, thereby improving the dispersion and interfacial bonding strength of the composite material.

[0114] Compared with the prior art, the present invention has the following beneficial effects:

[0115] The present invention prepares silicon carbide microspheres by reacting polycarbosilane with polyaniline in a high-temperature inert atmosphere. Polycarbosilane provides a silicon source, while polyaniline provides a carbon source and auxiliary decomposition products, ensuring the uniformity of the particle size and surface smoothness of the silicon carbide microspheres. To improve the chemical inertness, poor dispersibility, and insufficient interfacial bonding strength of the silicon carbide surface, the present invention hydrothermally grows molybdenum disulfide on its surface to form a core-shell silicon carbide / molybdenum disulfide composite material, further improving thermal conductivity and surface activity. At the same time, through coating with boron trifluoride etherate complex and phenyltrimethoxysilane, the electrical insulation, flame retardancy, and environmental stability of the composite material are significantly enhanced, laying the foundation for the development of high-performance insulating materials.

[0116] The present invention prepares a metal organic supramolecular cage by reacting trimesic acid with zinc nitrate, and uses it as a functional filler for high-performance insulating materials. The metal organic supramolecular cage significantly improves the dielectric properties and voltage resistance of the composite material with its high specific surface area and controllable microstructure, but its mechanical properties and thermal conductivity are insufficient. The present invention modifies the metal organic supramolecular cage by introducing carbon nitride. The high thermal conductivity and chemical stability of carbon nitride significantly make up for the shortcomings of the metal organic supramolecular cage. At the same time, its surface active functional groups combine with the surface of the metal organic supramolecular cage to enhance the interfacial bonding force. In addition, the surface modification with trifluoropropyltriethoxysilane further optimizes the dispersibility and interfacial compatibility of the metal organic supramolecular cage in the matrix.

[0117] Similarly, in the present invention, carbon nanotubes are introduced as high-strength, high-thermal-conductivity fillers to enhance the mechanical properties and thermal conductivity of the composite material. However, the surface of unmodified carbon nanotubes is highly chemically inert, has poor dispersibility and high conductivity. The present invention introduces hydroxyl and carboxyl groups on its surface through acid treatment, thereby improving its surface activity and dispersibility. Subsequently, through lanthanum ion modification, a rare earth oxide layer is formed on the surface of the carbon nanotubes, which reduces its conductivity and improves its high-temperature resistance. Furthermore, boron nitride is compounded with lanthanum-modified carbon nanotubes, which significantly improves the thermal conductivity and insulation properties of the composite material. Finally, through surface modification with 3-aminopropyltriethoxysilane, the interfacial bonding force of the carbon nanotubes and the uniform dispersion in the matrix are further improved;

[0118] The present invention significantly improves the performance of the composite material through the synergistic effects between multiple components. The core-shell structure of silicon carbide and molybdenum disulfide enhances thermal conductivity and interfacial bonding, while the organoboron coating further improves electrical insulation and flame retardancy. The combination of metal-organic supramolecular cages and carbon nitride improves thermal conductivity, interfacial bonding, and electrical insulation, while the combination of carbon nanotubes and metal-organic supramolecular cages significantly enhances the mechanical properties and dispersibility of the composite material. These synergistic effects optimize the thermal, electrical, and mechanical properties of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0119] Figure 1 This is a scanning electron microscope image of the silicon carbide / molybdenum disulfide composite material provided in Example 1 of the present invention;

[0120] Figure 2 This is a transmission electron microscope image of the silicon carbide / molybdenum disulfide composite material provided in Example 1 of the present invention;

[0121] Figure 3 This is a transmission electron micrograph of the carbon nitride-modified metal organic supramolecular cage provided in Example 1 of the present invention;

[0122] Figure 4 This is a scanning electron microscope image of the boron nitride / lanthanum modified carbon nanotubes provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0123] The technical solutions of the present invention are described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments described herein are specific embodiments of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be understood as limiting the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments described herein.

[0124] The chemical reagents used in the examples and comparative examples of the present invention are all commercially available products without further purification or treatment.

[0125] Example 1

[0126] This embodiment provides a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack and a preparation method thereof. The preparation method specifically includes the following steps:

[0127] S11: polycarbosilane and polyaniline were mixed in a mass ratio of 1:11, reacted at a constant temperature of 1450° C. under an inert atmosphere for 2.8 hours, cooled, and filtered to obtain a first product, which was then immersed in a mixed acid solution for 5 hours, centrifuged, washed, and dried to obtain silicon carbide microspheres, wherein the volume ratio of hydrofluoric acid to nitric acid in the mixed acid solution was 2.7:1; and the mass ratio of the first product to the mixed acid solution was 1:24;

[0128] S12: Dispersing silicon carbide microspheres at a mass fraction of 1 wt.% in deionized water, adding ammonium heptamolybdate and sodium sulfide after ultrasonic dispersion, and hydrothermally reacting at 174°C for 12 hours, wherein the molar ratio of ammonium heptamolybdate to sodium sulfide is 1:2; and the mass ratio of silicon carbide to ammonium heptamolybdate is 1:0.25; centrifuging, washing, and drying to obtain a silicon carbide / molybdenum disulfide composite material; Figure 1 From the scanning electron microscope image, we can see that the molybdenum disulfide nanosheets are evenly compounded on the surface of silicon carbide microspheres. Figure 2 In its transmission electron microscope image, a clear core-shell structure can be observed, indicating that molybdenum disulfide nanosheets are evenly attached to the surface of silicon carbide microspheres.

[0129] S13: Boron trifluoride etherate complex and phenyltrimethoxysilane are dissolved in tetrahydrofuran at a molar ratio of 1.1:1, stirred for 70 minutes to obtain a modified solution, wherein the total mass fraction of the boron trifluoride etherate complex and phenyltrimethoxysilane in the modified solution is 7 wt.%, and silicon carbide / molybdenum disulfide composite material is added to obtain reaction solution A, wherein the mass ratio of the silicon carbide / molybdenum disulfide composite material to the modified solution is 1:20, stirred at a constant temperature of 60° C. for 6 hours, and then cured at 270° C. for 2 hours to obtain an organoboron-coated silicon carbide / molybdenum disulfide composite material;

[0130] S21: dissolving trimesic acid and zinc nitrate hexahydrate in a mixed solvent of N,N-dimethylformamide and deionized water at a molar ratio of 1:15, wherein the volume ratio of N,N-dimethylformamide to deionized water in the mixed solution is 4.7:1, and the total concentration of trimesic acid and zinc nitrate hexahydrate in the mixed solution is 0.07 M, and subjecting the mixture to a solvothermal reaction at 120° C. for 47 h. Filtering and washing the mixture to obtain a metal organic supramolecular cage;

[0131] S22: calcining melamine at 550° C. for 4 h to obtain carbon nitride, adding the carbon nitride at a mass fraction of 3 wt.% to concentrated nitric acid for reflux reaction, wherein the reflux reaction temperature is 120° C. and the time is 8 h, filtering, washing, and drying to obtain modified carbon nitride, dispersing the modified carbon nitride and the metal organic supramolecular cage in N,N-dimethylformamide at a mass ratio of 1.1:1, wherein the mass fraction of the modified carbon nitride is 1.6 wt.%, mixing evenly, and then performing a solvothermal reaction at 130° C. for 12 h, filtering, washing, and drying to obtain the carbon nitride-modified metal organic supramolecular cage; Figure 3 From its transmission electron microscopy image, it can be observed that the metal organic supramolecular cage has a spherical or nanocage structure, and its outer layer has a lighter lamellar distribution. Different contrast areas indicate that there is a clear phase interface between the supramolecular cage and the carbon nitride layer, indicating that the carbon nitride modification uniformly covers the supramolecular cage.

[0132] S23: dispersing a carbon nitride modified metal organic supramolecular cage in anhydrous toluene at a mass fraction of 1.8 wt.%, adding trifluoropropyltriethoxysilane, wherein the amount of trifluoropropyltriethoxysilane accounts for 5% of the mass of the carbon nitride modified metal organic supramolecular cage, and reflux reacting at 118° C. for 6 h. After centrifugation, washing, and drying, a pretreated product is obtained, which is vacuum cured at 130° C. for 2 h to obtain a composite modified metal organic supramolecular cage;

[0133] S31: modifying carbon nanotubes in a modifying acid solution at 85° C. for 5 h with stirring to obtain modified carbon nanotubes, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid in the modifying acid solution is 3.7:1, and the mass ratio of carbon nanotubes to the modifying acid solution is 1:25; dispersing the modified carbon nanotubes in a 0.15 M lanthanum nitrate solution, wherein the mass ratio of lanthanum nitrate to modified carbon nanotubes is 1:10; adding sodium hydroxide to adjust the pH to 8 to obtain a reaction solution B; heat-treating the solution at 495° C. for 1.5 h under an argon atmosphere; filtering, washing, and drying to obtain lanthanum-modified carbon nanotubes;

[0134] S32: ultrasonically exfoliating hexagonal boron nitride in N-methylpyrrolidone, wherein the concentration of hexagonal boron nitride in N-methylpyrrolidone is 0.7 mg / mL, and collecting the supernatant by centrifugation for later use; dispersing lanthanum-modified carbon nanotubes in N-methylpyrrolidone to obtain a first dispersion, wherein the concentration of lanthanum-modified carbon nanotubes in the first dispersion is 1.7 mg / mL; mixing with the supernatant at a mass ratio of 1.5:1 for reaction for 2.7 hours, vacuum filtering, pre-drying at 77°C for 3 hours, and heat treating at 290°C for 25 minutes to obtain boron nitride / lanthanum-modified carbon nanotubes; Figure 4 The scanning electron microscope image shows that the surface of the carbon nanotube is covered with a thin and flake-like structure of boron nitride sheets.

[0135] S33: Boron nitride / lanthanum modified carbon nanotubes are dispersed in anhydrous ethanol at a mass fraction of 2.6 wt.%, 3-aminopropyltriethoxysilane in an amount of 5% by mass of the boron nitride / lanthanum modified carbon nanotubes and triethylamine in an amount of 0.5% by mass of the boron nitride / lanthanum modified carbon nanotubes are added, the mixture is mixed evenly, and the mixture is reacted at a constant temperature of 55° C. for 2.7 h. The mixture is filtered, washed, pre-dried at 77° C. for 2 h, and then cured at 144° C. for 2.8 h to obtain composite modified lanthanum modified carbon nanotubes;

[0136] A1: Polysilazane is dispersed in anhydrous toluene at a mass fraction of 20 wt.%, and after uniform dispersion, an organic boron-coated silicon carbide / molybdenum disulfide composite material, a composite modified metal organic supramolecular cage, a composite modified lanthanum-modified carbon nanotube, a crosslinker vinyltrimethoxysilane and a flame retardant aluminum hydroxide are added in sequence, and stirred to obtain a mixed solution, which is poured into a mold for degassing, pre-cured at 77°C for 3.6 hours, heat-cured at 230°C under an inert atmosphere for 2 hours, and then naturally cooled to obtain a high-voltage polysilazane-based insulating material for new energy vehicle power battery packs, wherein the mass ratio of polysilazane, organic boron-coated silicon carbide / molybdenum disulfide composite material, composite modified metal organic supramolecular cage, composite modified lanthanum-modified carbon nanotube, crosslinker and flame retardant is 82:35:38:30:4.6:3.

[0137] Example 2

[0138] This embodiment provides a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack and a preparation method thereof. The preparation method specifically includes the following steps:

[0139] S11: polycarbosilane and polyaniline were mixed in a mass ratio of 1:1.15, reacted at a constant temperature of 1480° C. under an inert atmosphere for 2.6 hours, cooled, and filtered to obtain a first product, which was then immersed in a mixed acid solution for 6 hours, centrifuged, washed, and dried to obtain silicon carbide microspheres, wherein the volume ratio of hydrofluoric acid to nitric acid in the mixed acid solution was 3:1; and the mass ratio of the first product to the mixed acid solution was 1:30;

[0140] S12: Silicon carbide microspheres with a mass fraction of 1.1wt . % was dispersed in deionized water, and after ultrasonic dispersion, ammonium heptamolybdate and sodium sulfide were added, followed by hydrothermal reaction at 180° C. for 13 hours, wherein the molar ratio of ammonium heptamolybdate to sodium sulfide was 1:3; the mass ratio of silicon carbide to ammonium heptamolybdate was 1:0.3; and the silicon carbide / molybdenum disulfide composite material was obtained by centrifugation, washing, and drying.

[0141] S13: Boron trifluoride etherate complex and phenyltrimethoxysilane are dissolved in tetrahydrofuran at a molar ratio of 0.9:1, stirred for 80 minutes to obtain a modified solution, wherein the total mass fraction of the boron trifluoride etherate complex and phenyltrimethoxysilane in the modified solution is 8 wt.%, and silicon carbide / molybdenum disulfide composite material is added to obtain reaction solution A, wherein the mass ratio of the silicon carbide / molybdenum disulfide composite material to the modified solution is 1:25, stirred at a constant temperature of 67° C. for 6.7 hours, and then cured at 260° C. for 2.3 hours to obtain an organoboron-coated silicon carbide / molybdenum disulfide composite material;

[0142] S21: dissolving trimesic acid and zinc nitrate hexahydrate in a mixed solvent of N,N-dimethylformamide and deionized water at a molar ratio of 1:18, wherein the volume ratio of N,N-dimethylformamide to deionized water in the mixed solution is 5:1, and the total concentration of trimesic acid and zinc nitrate hexahydrate in the mixed solution is 0.1 M, performing a solvothermal reaction at 130° C. for 50 h, filtering, and washing to obtain a metal organic supramolecular cage;

[0143] S22: calcining melamine at 570° C. for 5 h to obtain carbon nitride, adding the carbon nitride at a mass fraction of 4 wt.% to concentrated nitric acid for reflux reaction, wherein the reflux reaction temperature is 130° C. for 9 h, filtering, washing, and drying to obtain modified carbon nitride, dispersing the modified carbon nitride and the metal organic supramolecular cage in N,N-dimethylformamide at a mass ratio of 1:1, wherein the mass fraction of the modified carbon nitride is 2 wt.%, mixing evenly, and performing a solvothermal reaction at 150° C. for 13 h, filtering, washing, and drying to obtain the carbon nitride-modified metal organic supramolecular cage;

[0144] S23: Carbon nitride modified metal organic supramolecular cage with a mass fraction of 2wt . % was dispersed in anhydrous toluene, trifluoropropyltriethoxysilane was added, wherein the amount of trifluoropropyltriethoxysilane accounted for 5.6% of the mass of the carbon nitride modified metal organic supramolecular cage, and refluxed at 123°C for 7 hours. After centrifugation, washing and drying, a pretreated product was obtained, which was vacuum cured at 140°C for 2.3 hours to obtain a composite modified metal organic supramolecular cage;

[0145] S31: modifying carbon nanotubes in a modifying acid solution at 90° C. for 6 h with stirring to obtain modified carbon nanotubes, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid in the modifying acid solution is 4:1, and the mass ratio of carbon nanotubes to the modifying acid solution is 1:30; dispersing the modified carbon nanotubes in a 0.12 M lanthanum nitrate solution, wherein the mass ratio of lanthanum nitrate to modified carbon nanotubes is 1:9; adding sodium hydroxide to adjust the pH to 9 to obtain a reaction solution B; heat-treating the solution at 510° C. for 2 h under an argon atmosphere; filtering, washing, and drying to obtain lanthanum-modified carbon nanotubes;

[0146] S32: ultrasonically exfoliating hexagonal boron nitride in N-methylpyrrolidone, wherein the concentration of hexagonal boron nitride in N-methylpyrrolidone is 0.9 mg / mL, and collecting the supernatant by centrifugation for later use; dispersing lanthanum-modified carbon nanotubes in N-methylpyrrolidone to obtain a first dispersion, wherein the concentration of lanthanum-modified carbon nanotubes in the first dispersion is 1.2 mg / mL; mixing with the supernatant at a mass ratio of 1.2:1 for reaction for 3 hours, vacuum filtering, pre-drying at 73°C for 3.4 hours, and heat treating at 300°C for 35 minutes to obtain boron nitride / lanthanum-modified carbon nanotubes;

[0147] S33: Boron nitride / lanthanum modified carbon nanotubes are dispersed in anhydrous ethanol at a mass fraction of 3 wt.%, 3-aminopropyltriethoxysilane in an amount of 4% by mass of the boron nitride / lanthanum modified carbon nanotubes and triethylamine in an amount of 1% by mass of the boron nitride / lanthanum modified carbon nanotubes are added, the mixture is mixed evenly, and the mixture is reacted at a constant temperature of 58° C. for 2.3 h. The mixture is filtered, washed, pre-dried at 73° C. for 3 h, and then cured at 148° C. for 3 h to obtain composite modified lanthanum modified carbon nanotubes;

[0148] A1: Polysilazane is dispersed in anhydrous toluene at a mass fraction of 24 wt.%, and after uniform dispersion, an organic boron-coated silicon carbide / molybdenum disulfide composite material, a composite modified metal organic supramolecular cage, a composite modified lanthanum-modified carbon nanotube, a crosslinker vinyl triethoxysilane, and a flame retardant magnesium hydroxide are added in sequence and stirred to obtain a mixed solution, which is poured into a mold for degassing, pre-cured at 73° C. for 3.4 h, heat-cured at 240° C. under an inert atmosphere for 2.3 h, and then naturally cooled to obtain a high-voltage polysilazane-based insulating material for new energy vehicle power battery packs, wherein the mass ratio of polysilazane, organic boron-coated silicon carbide / molybdenum disulfide composite material, composite modified metal organic supramolecular cage, composite modified lanthanum-modified carbon nanotube, crosslinker, and flame retardant is 80:37:40:25:4:3.5.

[0149] Example 3

[0150] This embodiment provides a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack and a preparation method thereof. The preparation method specifically includes the following steps:

[0151] S11: polycarbosilane and polyaniline are mixed in a mass ratio of 1:1, reacted at a constant temperature of 1400° C. under an inert atmosphere for 2 hours, cooled, and filtered to obtain a first product, which is then immersed in a mixed acid solution for 4 hours, centrifuged, washed, and dried to obtain silicon carbide microspheres, wherein the volume ratio of hydrofluoric acid to nitric acid in the mixed acid solution is 2:1; and the mass ratio of the first product to the mixed acid solution is 1:20;

[0152] S12: Silicon carbide microspheres with a mass fraction of 0.8wt . % was dispersed in deionized water, and after ultrasonic dispersion, ammonium heptamolybdate and sodium sulfide were added, followed by hydrothermal reaction at 170° C. for 10 hours, wherein the molar ratio of ammonium heptamolybdate to sodium sulfide was 1:2.6; the mass ratio of silicon carbide to ammonium heptamolybdate was 1:0.2; and the silicon carbide / molybdenum disulfide composite material was obtained by centrifugation, washing, and drying.

[0153] S13: Boron trifluoride etherate complex and phenyltrimethoxysilane are dissolved in tetrahydrofuran at a molar ratio of 1:1 and stirred for 60 minutes to obtain a modified solution, wherein the total mass fraction of the boron trifluoride etherate complex and phenyltrimethoxysilane in the modified solution is 5 wt.%, and silicon carbide / molybdenum disulfide composite material is added to obtain reaction solution A, wherein the mass ratio of the silicon carbide / molybdenum disulfide composite material to the modified solution is 1:15, and the mixture is stirred at a constant temperature of 63° C. for 5 hours and then cured at 250° C. for 1.5 hours to obtain an organoboron-coated silicon carbide / molybdenum disulfide composite material;

[0154] S21: dissolving trimesic acid and zinc nitrate hexahydrate in a mixed solvent of N,N-dimethylformamide and deionized water at a molar ratio of 1:1, wherein the volume ratio of N,N-dimethylformamide to deionized water in the mixed solution is 4:1, and the total concentration of trimesic acid and zinc nitrate hexahydrate in the mixed solution is 0.05 M, performing a solvothermal reaction at 110° C. for 45 h, filtering, and washing to obtain a metal organic supramolecular cage;

[0155] S22: calcining melamine at 530° C. for 3 h to obtain carbon nitride, adding the carbon nitride at a mass fraction of 2 wt.% to concentrated nitric acid for reflux reaction, wherein the reflux reaction temperature is 128° C. for 7 h, filtering, washing, and drying to obtain modified carbon nitride, dispersing the modified carbon nitride and the metal organic supramolecular cage in N,N-dimethylformamide at a mass ratio of 0.8:1, wherein the mass fraction of the modified carbon nitride is 1 wt.%, mixing evenly, and then performing a solvothermal reaction at 140° C. for 10 h, filtering, washing, and drying to obtain the carbon nitride-modified metal organic supramolecular cage;

[0156] S23: Carbon nitride modified metal organic supramolecular cage with a mass fraction of 1wt . % was dispersed in anhydrous toluene, trifluoropropyltriethoxysilane was added, wherein the amount of trifluoropropyltriethoxysilane accounted for 4% of the mass of the carbon nitride modified metal organic supramolecular cage, and refluxed at 115°C for 5 hours. After centrifugation, washing and drying, a pretreated product was obtained, which was vacuum cured at 120°C for 1.5 hours to obtain a composite modified metal organic supramolecular cage;

[0157] S31: modifying carbon nanotubes in a modifying acid solution at 80° C. for 6.5 h with stirring to obtain modified carbon nanotubes, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid in the modifying acid solution is 3:1, and the mass ratio of carbon nanotubes to the modifying acid solution is 1:20; dispersing the modified carbon nanotubes in a 0.1 M lanthanum nitrate solution, wherein the mass ratio of lanthanum nitrate to modified carbon nanotubes is 1:8; adding sodium hydroxide to adjust the pH to 8.8 to obtain a reaction solution B; heat-treating the solution at 480° C. for 1 h under an argon atmosphere; filtering, washing, and drying to obtain lanthanum-modified carbon nanotubes;

[0158] S32: ultrasonically exfoliating hexagonal boron nitride in N-methylpyrrolidone, wherein the concentration of hexagonal boron nitride in N-methylpyrrolidone is 0.5 mg / mL, and collecting the supernatant by centrifugation for later use. Lanthanum-modified carbon nanotubes are dispersed in N-methylpyrrolidone to obtain a first dispersion, wherein the concentration of lanthanum-modified carbon nanotubes in the first dispersion is 1 mg / mL. The dispersion is mixed with the supernatant at a mass ratio of 1.6:1 for 2 h, and then vacuum filtered, pre-dried at 70° C. for 3.8 h, and heat treated at 280° C. for 28 min to obtain boron nitride / lanthanum-modified carbon nanotubes.

[0159] S33: Boron nitride / lanthanum modified carbon nanotubes are dispersed in anhydrous ethanol at a mass fraction of 2 wt.%, 3-aminopropyltriethoxysilane in an amount of 5.4% by mass of the boron nitride / lanthanum modified carbon nanotubes and triethylamine in an amount of 0.8% by mass of the boron nitride / lanthanum modified carbon nanotubes are added, the mixture is mixed evenly, and the mixture is reacted at a constant temperature of 50° C. for 2 h, filtered, washed, pre-dried at 70° C. for 2.7 h, and then cured at 140° C. for 2 h to obtain composite modified lanthanum modified carbon nanotubes;

[0160] A1: Polysilazane is dispersed in anhydrous toluene at a mass fraction of 22 wt.%, and after uniform dispersion, an organic boron-coated silicon carbide / molybdenum disulfide composite material, a composite modified metal organic supramolecular cage, a composite modified lanthanum-modified carbon nanotube, a crosslinker vinyl trimethoxysilane, γ-methacryloxypropyl trimethoxysilane and a flame retardant aluminum hydroxide and ammonium polyphosphate are added in sequence, and stirred to obtain a mixed solution, which is poured into a mold for degassing, pre-cured at 70° C. for 3 h, heat-cured at 200° C. under an inert atmosphere for 2.7 h, and then naturally cooled to obtain a high-voltage polysilazane-based insulating material for new energy vehicle power battery packs, wherein the mass ratio of polysilazane, organic boron-coated silicon carbide / molybdenum disulfide composite material, composite modified metal organic supramolecular cage, composite modified lanthanum-modified carbon nanotube, crosslinker and flame retardant is 83:30:35:32:4.8:3.7.

[0161] Example 4

[0162] This embodiment provides a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack and a preparation method thereof. The preparation method specifically includes the following steps:

[0163] S11: polycarbosilane and polyaniline are mixed in a mass ratio of 1:1.2, reacted at a constant temperature of 1500° C. under an inert atmosphere for 3 hours, cooled, and filtered to obtain a first product, which is then immersed in a mixed acid solution for 5.6 hours, centrifuged, washed, and dried to obtain silicon carbide microspheres, wherein the volume ratio of hydrofluoric acid to nitric acid in the mixed acid solution is 2.3:1; and the mass ratio of the first product to the mixed acid solution is 1:26;

[0164] S12: Silicon carbide microspheres with a mass fraction of 1.2wt . % was dispersed in deionized water, and after ultrasonic dispersion, ammonium heptamolybdate and sodium sulfide were added, followed by hydrothermal reaction at 178° C. for 14 hours, wherein the molar ratio of ammonium heptamolybdate to sodium sulfide was 1:2.3; the mass ratio of silicon carbide to ammonium heptamolybdate was 1:0.28; and the silicon carbide / molybdenum disulfide composite material was obtained by centrifugation, washing, and drying.

[0165] S13: Boron trifluoride etherate complex and phenyltrimethoxysilane are dissolved in tetrahydrofuran at a molar ratio of 1.2:1, stirred for 90 minutes to obtain a modified solution, wherein the total mass fraction of the boron trifluoride etherate complex and phenyltrimethoxysilane in the modified solution is 6 wt.%, and silicon carbide / molybdenum disulfide composite material is added to obtain reaction solution A, wherein the mass ratio of the silicon carbide / molybdenum disulfide composite material to the modified solution is 1:22, stirred at a constant temperature of 70°C for 7 hours, and then cured at 280°C for 2.5 hours to obtain an organoboron-coated silicon carbide / molybdenum disulfide composite material;

[0166] S21: dissolving trimesic acid and zinc nitrate hexahydrate in a mixed solvent of N,N-dimethylformamide and deionized water at a molar ratio of 1:2, wherein the volume ratio of N,N-dimethylformamide to deionized water in the mixed solution is 4.5:1, and the total concentration of trimesic acid and zinc nitrate hexahydrate in the mixed solution is 0.09 M, and subjecting the mixture to a solvothermal reaction at 125° C. for 48 h. Filtering and washing the mixture to obtain a metal organic supramolecular cage;

[0167] S22: calcining melamine at 580° C. for 4.5 h to obtain carbon nitride, adding the carbon nitride at a mass fraction of 5 wt.% to concentrated nitric acid for reflux reaction, wherein the reflux reaction temperature is 123° C. and the time is 7.8 h, filtering, washing, and drying to obtain modified carbon nitride, dispersing the modified carbon nitride and the metal organic supramolecular cage in N,N-dimethylformamide at a mass ratio of 1.2:1, wherein the mass fraction of the modified carbon nitride is 1.2 wt.%, mixing evenly, and then performing a solvothermal reaction at 145° C. for 14 h, filtering, washing, and drying to obtain the carbon nitride-modified metal organic supramolecular cage;

[0168] S23: Carbon nitride modified metal organic supramolecular cage with a mass fraction of 1.2wt . % was dispersed in anhydrous toluene, trifluoropropyltriethoxysilane was added, wherein the amount of trifluoropropyltriethoxysilane accounted for 6% of the mass of the carbon nitride modified metal organic supramolecular cage, and refluxed at 125°C for 6.7h. After centrifugation, washing and drying, a pretreated product was obtained, which was vacuum cured at 134°C for 2.5h to obtain a composite modified metal organic supramolecular cage;

[0169] S31: modifying carbon nanotubes in a modifying acid solution at 88° C. for 7 h with stirring to obtain modified carbon nanotubes, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid in the modifying acid solution is 3.4:1, and the mass ratio of carbon nanotubes to the modifying acid solution is 1:28; dispersing the modified carbon nanotubes in a 0.2 M lanthanum nitrate solution, wherein the mass ratio of lanthanum nitrate to modified carbon nanotubes is 1:12; adding sodium hydroxide to adjust the pH to 8.3 to obtain reaction solution B; heat-treating the reaction solution at 520° C. for 1.2 h under an argon atmosphere; filtering, washing, and drying to obtain lanthanum-modified carbon nanotubes;

[0170] S32: ultrasonically exfoliating hexagonal boron nitride in N-methylpyrrolidone, wherein the concentration of hexagonal boron nitride in N-methylpyrrolidone is 1 mg / mL, and collecting the supernatant by centrifugation for later use; dispersing lanthanum-modified carbon nanotubes in N-methylpyrrolidone to obtain a first dispersion, wherein the concentration of lanthanum-modified carbon nanotubes in the first dispersion is 2 mg / mL; mixing with the supernatant at a mass ratio of 1.8:1 for reaction for 2.3 hours, vacuum filtering, pre-drying at 80°C for 4 hours, and heat treating at 320°C for 30 minutes to obtain boron nitride / lanthanum-modified carbon nanotubes;

[0171] S33: Boron nitride / lanthanum modified carbon nanotubes are dispersed in anhydrous ethanol at a mass fraction of 2.3 wt.%, 3-aminopropyltriethoxysilane in an amount of 6% by mass of the boron nitride / lanthanum modified carbon nanotubes and triethylamine in an amount of 0.92% by mass of the boron nitride / lanthanum modified carbon nanotubes are added, the mixture is mixed evenly, and the mixture is reacted at a constant temperature of 60°C for 3 hours, filtered, washed, pre-dried at 80°C for 2.3 hours, and then cured at 150°C for 2.3 hours to obtain composite modified lanthanum modified carbon nanotubes;

[0172] A1: Polysilazane is dispersed in anhydrous toluene at a mass fraction of 25 wt.%, and after uniform dispersion, an organic boron-coated silicon carbide / molybdenum disulfide composite material, a composite modified metal organic supramolecular cage, a composite modified lanthanum-modified carbon nanotube, a crosslinker vinyl trimethoxysilane, a vinyl triethoxysilane and a flame retardant aluminum hydroxide and magnesium hydroxide are added in sequence, and stirred to obtain a mixed solution, which is poured into a mold for degassing, pre-cured at 80° C. for 4 h, heat-cured at 250° C. under an inert atmosphere for 3 h, and then naturally cooled to obtain a high-voltage polysilazane-based insulating material for new energy vehicle power battery packs, wherein the mass ratio of polysilazane, organic boron-coated silicon carbide / molybdenum disulfide composite material, composite modified metal organic supramolecular cage, composite modified lanthanum-modified carbon nanotube, crosslinker and flame retardant is 85:40:45:35:5:4.

[0173] Comparative Example 1

[0174] This comparative example provides a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack. The difference from Example 1 is that in A1, the mass ratio of polysilazane, organic boron-coated silicon carbide / molybdenum disulfide composite material, composite modified metal organic supramolecular cage, composite modified lanthanum-modified carbon nanotube, crosslinker and flame retardant is 82:45:38:30:4.6:3.

[0175] Comparative Example 2

[0176] This comparative example provides a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack. The difference from Example 1 is that in A1, the mass ratio of polysilazane, organic boron-coated silicon carbide / molybdenum disulfide composite material, composite modified metal organic supramolecular cage, composite modified lanthanum-modified carbon nanotube, crosslinker and flame retardant is 82:20:38:30:4.6:3.

[0177] Comparative Example 3

[0178] This comparative example provides a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack. The difference from Example 1 is that in A1, the mass ratio of polysilazane, organic boron-coated silicon carbide / molybdenum disulfide composite material, composite modified metal organic supramolecular cage, composite modified lanthanum-modified carbon nanotube, crosslinker and flame retardant is 82:45:48:30:4.6:3.

[0179] Comparative Example 4

[0180] This comparative example provides a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack. The difference from Example 1 is that in A1, the mass ratio of polysilazane, organic boron-coated silicon carbide / molybdenum disulfide composite material, composite modified metal organic supramolecular cage, composite modified lanthanum-modified carbon nanotube, crosslinker and flame retardant is 82:45:30:30:4.6:3.

[0181] Comparative Example 5

[0182] This comparative example provides a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack. The difference from Example 1 is that in A1, the mass ratio of polysilazane, organic boron-coated silicon carbide / molybdenum disulfide composite material, composite modified metal organic supramolecular cage, composite modified lanthanum-modified carbon nanotube, crosslinker and flame retardant is 82:45:30:40:4.6:3.

[0183] Comparative Example 6

[0184] This comparative example provides a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack. The difference from Example 1 is that in A1, the mass ratio of polysilazane, organic boron-coated silicon carbide / molybdenum disulfide composite material, composite modified metal organic supramolecular cage, composite modified lanthanum-modified carbon nanotube, crosslinker and flame retardant is 82:45:48:20:4.6:3.

[0185] The performance test of the high voltage-resistant polysilazane-based insulation materials for new energy vehicle power battery packs of Examples 1-4 and Comparative Examples 1-6 was conducted. The specific process is as follows:

[0186] The material was prepared into a circular specimen with a thickness of 0.3 mm and a diameter of 90 mm. The test was carried out using a computer-controlled voltage breakdown tester in the DC breakdown mode with a voltage ramp rate of 1 kV / mm. The average value of 5 tests was taken as the high-voltage DC breakdown strength value.

[0187] The volume resistivity of the sample was tested according to GB / T 31838.2-2019;

[0188] The test results are shown in Table 1.

[0189] Table 1: Test results of insulation material properties of Examples 1-4 and Comparative Examples 1-6

[0190]

[0191] From the test results of Example 1 and Comparative Examples 1 and 2, it can be seen that when the addition amount of the organic boron-coated silicon carbide / molybdenum disulfide composite material is too high, the distance between the silicon carbide particles is reduced, and a conductive path is easily formed. At the same time, the molybdenum disulfide layers on its surface are stacked, thereby increasing the probability of electron transition, resulting in a decrease in the breakdown field strength and volume resistivity of the insulating material; when the addition amount is insufficient, the overall thermal diffusion is limited, and the electric field concentration in the local area causes the macroscopic breakdown value to be lowered, but the overall lack of polar groups makes the insulating network relatively dense, thereby increasing the volume resistivity.

[0192] From the test results of Example 1 and Comparative Examples 3 and 4, it can be seen that when the amount of the composite modified metal-organic supramolecular cage added is too much, a local conductive region is formed at the metal center of the metal-organic supramolecular cage, and at the same time, the excessive carbon nitride modification layer leads to enhanced polarization, which reduces the breakdown field strength and volume resistivity; when the amount of addition is insufficient, the insufficient number of charge traps leads to easy migration of electrons, and the sparse distribution of the cage structure of the metal-organic supramolecular cage causes uneven electric field distribution, which reduces the breakdown field strength and volume resistivity.

[0193] From the test results of Example 1 and Comparative Examples 5 and 6, it can be seen that when the amount of composite modified lanthanum-modified carbon nanotubes added is too much, the carbon nanotubes easily form a conductive network, and the excess lanthanum ions lead to enhanced local polarization. At the same time, the gap between the boron nitride layers is reduced, resulting in an increase in the probability of electron tunneling, which significantly reduces the breakdown field strength and the volume resistivity. When the amount of addition is insufficient, due to the insufficient deep energy level trap density of the lanthanum ions and the incomplete synergistic network of the boron nitride / lanthanum-modified carbon nanotubes, the charge modulation ability is weakened, the breakdown field strength is reduced, and the volume resistivity is increased.

[0194] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack, characterized in that: The preparation method comprises: A1: Disperse polysilazane in anhydrous toluene, and after uniform dispersion, add organic boron-coated silicon carbide / molybdenum disulfide composite material, composite modified metal organic supramolecular cage, composite modified lanthanum-modified carbon nanotube, crosslinker and flame retardant in sequence, stir to obtain a mixed solution, pour the mixed solution into a mold for degassing, pre-curing, heat curing under an inert atmosphere, and then naturally cool to obtain a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack, wherein the mass ratio of polysilazane, organic boron-coated silicon carbide / molybdenum disulfide composite material, composite modified metal organic supramolecular cage, composite modified lanthanum-modified carbon nanotube, crosslinker and flame retardant in the high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack is: (80-85):(30-40):(35-45):(25-35):(4-5):(3-4); The preparation method of the composite modified metal organic supramolecular cage is as follows: S21: dissolving trimesic acid and zinc nitrate hexahydrate in a mixed solvent of N,N-dimethylformamide and deionized water, performing a solvothermal reaction, filtering, and washing to obtain a metal organic supramolecular cage; S22: calcining melamine to obtain carbon nitride, adding the carbon nitride to concentrated nitric acid for reflux reaction, filtering, washing, and drying to obtain modified carbon nitride, dispersing the modified carbon nitride and the metal organic supramolecular cage in N,N-dimethylformamide, mixing them uniformly, and then performing a solvothermal reaction, filtering, washing, and drying to obtain the carbon nitride-modified metal organic supramolecular cage; S23: dispersing the carbon nitride modified metal organic supramolecular cage in anhydrous toluene, adding trifluoropropyltriethoxysilane, reflux reaction, centrifuging, washing, and drying to obtain a pretreated product, and vacuum curing to obtain a composite modified metal organic supramolecular cage; The preparation method of the composite modified lanthanum-modified carbon nanotubes is as follows: S31: modifying carbon nanotubes by stirring in a modifying acid solution to obtain modified carbon nanotubes, dispersing the modified carbon nanotubes in a lanthanum nitrate solution, adding sodium hydroxide to adjust the pH to obtain a reaction solution B, heat-treating the solution under an argon atmosphere, filtering, washing, and drying to obtain lanthanum-modified carbon nanotubes; S32: ultrasonically exfoliating hexagonal boron nitride in N-methylpyrrolidone, collecting the supernatant by centrifugation for later use, dispersing lanthanum-modified carbon nanotubes in N-methylpyrrolidone to obtain a first dispersion, mixing the dispersion with the supernatant, and then vacuum filtering, pre-drying, and heat-treating to obtain boron nitride / lanthanum-modified carbon nanotubes; S33: Dispersing boron nitride / lanthanum modified carbon nanotubes in anhydrous ethanol, adding 3-aminopropyltriethoxysilane and triethylamine, mixing evenly and reacting at a constant temperature, filtering, washing, pre-drying and then curing to obtain composite modified lanthanum modified carbon nanotubes.

2. The method for preparing a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack according to claim 1, characterized in that: In A1: The mass fraction of the polysilazane in anhydrous toluene is 20-25 wt.%; The crosslinking agent is any one of vinyltrimethoxysilane, vinyltriethoxysilane or γ-methacryloxypropyltrimethoxysilane or a combination of two; The flame retardant is any one of aluminum hydroxide, magnesium hydroxide or ammonium polyphosphate or a combination of two thereof.

3. The method for preparing a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack according to claim 1, characterized in that: The preparation method of the organic boron-coated silicon carbide / molybdenum disulfide composite material is as follows: S11: mixing polycarbosilane and polyaniline, reacting them at a constant temperature under an inert atmosphere, cooling and filtering to obtain a first product, soaking the first product in a mixed acid solution, washing it by centrifugation, and drying it to obtain silicon carbide microspheres; S12: dispersing silicon carbide microspheres in deionized water, adding ammonium heptamolybdate and sodium sulfide after ultrasonic dispersion, and then hydrothermally reacting, centrifuging, washing, and drying to obtain a silicon carbide / molybdenum disulfide composite material; S13: dissolving a boron trifluoride ether complex and phenyltrimethoxysilane in tetrahydrofuran and stirring to obtain a modified solution, adding a silicon carbide / molybdenum disulfide composite material to obtain a reaction solution A, stirring at a constant temperature and then solidifying to obtain an organoboron-coated silicon carbide / molybdenum disulfide composite material.

4. The method for preparing a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack according to claim 3, characterized in that: In S11: The mass ratio of the polycarbosilane to the polyaniline is 1:(1-1.2); The volume ratio of hydrofluoric acid to nitric acid in the mixed acid solution is (2-3):1; The mass ratio of the first product to the mixed acid solution is 1:(20-30); In S12: The molar ratio of ammonium heptamolybdate to sodium sulfide is 1:(2-3); The mass ratio of the silicon carbide to ammonium heptamolybdate is 1:(0.2-0.3).

5. The method for preparing a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack according to claim 3, characterized in that: In S13: The molar ratio of the boron trifluoride ether complex to phenyltrimethoxysilane is (0.8-1.2):1; The total mass fraction of the boron trifluoride ether complex and phenyltrimethoxysilane in the modified solution is 5-8 wt.%; The solid-liquid mass ratio of the silicon carbide / molybdenum disulfide composite material to the modified solution is 1:(15-25).

6. The method for preparing a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack according to claim 1, characterized in that: In S21: The molar ratio of trimesic acid to zinc nitrate hexahydrate is 1:(1-2); The volume ratio of N,N-dimethylformamide to deionized water in the mixed solvent is (4-5):1; The total concentration of trimesic acid and zinc nitrate hexahydrate in the mixed solvent is 0.05-0.1 M; In S22: The mass ratio of the modified carbon nitride to the metal organic supramolecular cage is (0.8-1.2):1; In S23: The feeding amount of the trifluoropropyltriethoxysilane accounts for 4-6% of the mass of the carbon nitride modified metal organic supramolecular cage.

7. The method for preparing a high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack according to claim 1, characterized in that: In S31: The volume ratio of concentrated sulfuric acid to concentrated nitric acid in the modified acid solution is (3-4):1; The mass ratio of the lanthanum nitrate to the modified carbon nanotubes is 1:(8-12); In S32: The concentration of the hexagonal boron nitride in N-methylpyrrolidone is 0.5-1 mg / mL; The concentration of lanthanum-modified carbon nanotubes in the first dispersion is 1-2 mg / mL; The mass ratio of the first dispersion liquid to the supernatant liquid is (1.2-1.8):1; In S33: The amount of 3-aminopropyltriethoxysilane added is 4-6% of the mass of the boron nitride / lanthanum modified carbon nanotubes; The feeding amount of the triethylamine accounts for 0.5-1% of the mass of the boron nitride / lanthanum modified carbon nanotubes.

8. A high-voltage polysilazane-based insulating material for a new energy vehicle power battery pack, prepared by the preparation method according to any one of claims 1 to 7.

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