A PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler and its preparation method

Abstract

This invention discloses a PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler and its preparation method, relating to the field of polymer composite materials technology. The material comprises polypropylene, modified thermally conductive and insulating filler, thermal stabilizer, plasticizer, antioxidant, and lubricant. The modified thermally conductive and insulating filler consists of a point-sheet-wire synergistic thermally conductive framework composed of spherical α-alumina, hydroxylated hexagonal boron nitride nanosheets, and silicon nitride whiskers, sequentially forming a polydopamine anchoring layer, a magnesium-aluminum layered double hydroxide insulating locking layer, a polyphosphazene-siloxane-POSS composite shell, and a maleic anhydride-grafted polypropylene wax compatible coating layer. The resulting material possesses thermal conductivity, insulation, flame retardancy, heat resistance, mechanical stability, and processing performance, making it suitable for battery cell lead terminals and their surrounding insulating and thermally conductive structural components.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to a PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler and its preparation method. Background Technology

[0002] With the development of new energy vehicles, energy storage batteries, and high-rate charge-discharge battery systems, the cell lead terminals and their surrounding insulation components need to withstand localized heat accumulation caused by current flow, external mechanical assembly stress, and long-term thermal-oxidative aging during service. Therefore, the polymer materials used for cell lead terminals not only need to have good electrical insulation properties, but also high thermal conductivity, dimensional stability, heat resistance, and processing and molding performance.

[0003] Polypropylene (PP) materials are widely used in electrical insulation components and battery structural components due to their low density, low cost, good processability, good chemical corrosion resistance, and excellent electrical insulation properties. However, ordinary polypropylene has a low intrinsic thermal conductivity, making it difficult to conduct heat generated at the battery cell lead terminals in a timely manner. This can easily lead to excessively high local temperatures, thereby affecting the safety and lifespan of the battery system.

[0004] In existing technologies, the thermal conductivity of polypropylene materials is typically improved by adding inorganic thermally conductive and insulating fillers such as alumina, boron nitride, silicon nitride, and magnesium oxide. However, single particulate fillers are difficult to form continuous thermal conduction pathways in the polymer matrix, often requiring high filler amounts to achieve a significant improvement in thermal conductivity. High filler amounts, in turn, lead to decreased melt flowability, deterioration of mechanical properties, and processing difficulties. While lamellar boron nitride exhibits high in-plane thermal conductivity, it tends to agglomerate and stack in the resin matrix, resulting in poor interfacial compatibility. Whisker-type fillers, although beneficial for constructing linear thermally conductive networks, suffer from insufficient interfacial bonding with the resin matrix, easily leading to increased interfacial thermal resistance.

[0005] Furthermore, inorganic thermally conductive fillers have a strong surface polarity, resulting in poor compatibility with the non-polar polypropylene matrix. This makes them prone to agglomeration, delamination, or interfacial defects during mixing and molding, limiting the improvement in thermal conductivity and potentially affecting the material's electrical insulation and mechanical stability. Therefore, improving the dispersibility, interfacial bonding, and continuity of thermal conductivity pathways of fillers within the matrix while maintaining the electrical insulation and processing properties of polypropylene materials is a pressing technical challenge for PP-based battery cell lead terminal materials. Summary of the Invention

[0006] The purpose of this invention is to address the problems of insufficient thermal conductivity, poor dispersion of inorganic thermally conductive fillers, high interfacial thermal resistance, and decreased processing and mechanical properties under high filler content in existing PP-based battery cell lead terminal materials. This invention provides a PP-based battery cell lead terminal material containing modified insulating thermally conductive fillers and its preparation method. This material improves its thermal conductivity, interfacial compatibility, thermal stability, and processing performance while maintaining its electrical insulation properties by constructing a point-like, sheet-like, and linear composite thermally conductive framework and performing multi-layer interfacial modification on the composite framework.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler, which is formulated by the following components in parts by weight: 100 parts of polypropylene, 20-60 parts of modified thermally conductive and insulating filler, 0.1-2 parts of heat stabilizer, 0.1-5 parts of plasticizer, 0.1-1 parts of antioxidant, and 0.1-1 parts of lubricant.

[0008] Preferably, the modified thermally conductive and insulating filler is prepared from the following raw materials in parts by weight: 55-75 parts of spherical α-alumina micro powder, 12-24 parts of hydroxylated hexagonal boron nitride nanosheets, 4-10 parts of silicon nitride whiskers, 4-9 parts of magnesium nitrate hexahydrate, 1.5-4 parts of aluminum nitrate nonahydrate, 2-6 parts of urea, 1-2.8 parts of dopamine hydrochloride, 1-3 parts of 3-aminopropyltriethoxysilane, 0.6-1.8 parts of hexachlorocyclotriphosphazene, 0.5-1.6 parts of 4,4′-dihydroxydiphenyl sulfone, 0.8-2.5 parts of triethylamine, 0.4-1.2 parts of 3-mercaptopropyltrimethoxysilane, 0.3-1 part of octavinylcage-type silsesquioxane, 2-5 parts of maleic anhydride-grafted polypropylene wax, and 0.02-0.12 parts of dicumyl peroxide.

[0009] By adopting the above technical solution, preferably, the modified thermally conductive and insulating filler is a composite filler in which spherical α-alumina micropowder, hydroxylated hexagonal boron nitride nanosheets and silicon nitride whiskers together form a thermally conductive framework, wherein the spherical α-alumina micropowder serves as a point-like thermally conductive node, the hydroxylated hexagonal boron nitride nanosheets serve as a sheet-like thermally conductive bridge, and the silicon nitride whiskers serve as a linear thermally conductive framework; the surface of the composite filler is sequentially formed with a polydopamine anchoring layer, a magnesium-aluminum layered double hydroxide insulating locking layer, a polyphosphazene-siloxane-POSS composite shell layer, and a maleic anhydride-grafted polypropylene wax compatible coating layer.

[0010] By adopting the above technical solution, preferably, the preparation method of the modified thermally conductive and insulating filler includes the following steps: S1. Add spherical α-alumina micro powder and silicon nitride whiskers to anhydrous ethanol / deionized water mixture with a volume ratio of 90:10, control the solid-liquid mass ratio at 1:8-12, add 3-aminopropyltriethoxysilane, adjust the pH to 4.2-5.0 with glacial acetic acid, react at 55-65℃ and 600-900 r / min for 2-4 h, filter, wash with anhydrous ethanol, and vacuum dry at 80-90℃ for 8-12 h to obtain an aminated dot-line framework.

[0011] S2. The aminated dot-line framework and hydroxylated hexagonal boron nitride nanosheets are added to a Tris-HCl buffer solution with a pH of 8.3-8.8 and a concentration of 10 mmol / L. The solid-liquid mass ratio is controlled at 1:15-25. After ultrasonic dispersion for 30-45 min, the mixture is stirred at 25-35℃ and 500-800 r / min. Dopamine hydrochloride aqueous solution is added at a dropping rate of 0.5-1.0 mL / min. The reaction is carried out for 4-8 h. The mixture is then filtered, washed, and dried to obtain the polydopamine-anchored dot-sheet-line precursor.

[0012] S3. The polydopamine-anchored dot-plate-line precursor is dispersed in a deionized water / ethanol mixture with a volume ratio of 70:30, and the solid-liquid mass ratio is controlled at 1:10-18 to obtain a precursor dispersion. Magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and urea are prepared into a mixed salt solution and added to the precursor dispersion at a dropping rate of 0.7-1.3 mL / min. During the dropping process, the pH of the system is maintained at 9.2-9.8 with 0.5 mol / L sodium hydroxide solution. The mixture is aged at 75-85℃ and 800-1000 r / min for 3-5 h, filtered, and then vacuum dried at 90℃ for 8-10 h to obtain a magnesium-aluminum layered double hydroxide-locked insulating bridging precursor.

[0013] S4. Add the insulating bridging precursor to anhydrous acetonitrile, controlling the solid-liquid mass ratio to 1:15-25. Under nitrogen protection, add hexachlorocyclotriphosphazene, 4,4′-dihydroxydiphenyl sulfone, and triethylamine. Pre-react at 40-50℃ and 500-700 r / min for 1-2 h, then raise the temperature to 65-75℃ and react for 4-6 h. Filter and wash to obtain the polyphosphazene-coated precursor. Disperse the polyphosphazene-coated precursor in anhydrous toluene or anhydrous xylene, add 3-mercaptopropyltrimethoxysilane, octavinylcage-type silsesquioxane, and dicumyl peroxide. Under atmospheric protection, the reaction is carried out at 100-120℃ for 2-5 hours to allow the mercapto group in 3-mercaptopropyltrimethoxysilane to undergo an addition reaction with the vinyl group in octavinylcage-type silsesquioxane. After the reaction, the product is dispersed in a 90:10 volume ratio ethanol / deionized water mixture, the pH is adjusted to 8.0-9.0, and the reaction is carried out at 40-50℃ for 1-3 hours to allow the methoxysilane group to undergo hydrolysis and condensation. After filtration, the product is washed successively with ethanol and deionized water, and then vacuum dried at 70-80℃ for 10-14 hours to obtain a polyphosphazene-siloxane-POSS composite shell-coated precursor.

[0014] S5. The polyphosphazene-siloxane-POSS composite shell coating precursor and maleic anhydride-grafted polypropylene wax are added to a mixer and melt-coated at 160-175℃ and 60-100r / min for 8-15min. After cooling, crushing and passing through a 325-mesh sieve, the modified thermally conductive and insulating filler is obtained by vacuum drying at 80℃ for 6-10h.

[0015] By adopting the above technical solution, preferably, the D50 of the spherical α-alumina micro powder is 3-8 μm.

[0016] By adopting the above technical solution, preferably, the average diameter of the hydroxylated hexagonal boron nitride nanosheets is 0.1-1.0 μm.

[0017] By adopting the above technical solution, preferably, the diameter of the silicon nitride whiskers is 0.2-1.0 μm.

[0018] By adopting the above technical solution, preferably, the heat stabilizer is one or a combination of at least two of calcium stearate, zinc stearate, hydrotalcite, and pentaerythritol stearate.

[0019] By adopting the above technical solution, preferably, the antioxidant is composed of hindered phenolic antioxidants and phosphite antioxidants, and the mass ratio of the hindered phenolic antioxidants to the phosphite antioxidants is 1:0.5-2.

[0020] By adopting the above technical solution, preferably, the hindered phenolic antioxidant is one or a combination of at least two of pentaerythritol tetrakis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene.

[0021] By adopting the above technical solution, preferably, the phosphite antioxidant is one or a combination of at least two of tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, and bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite.

[0022] By adopting the above technical solution, preferably, the lubricant is one or a combination of at least two of ethylene bis-stearamide, polyethylene wax, stearamide, and silicone powder.

[0023] By adopting the above technical solution, preferably, the plasticizer is one or a combination of at least two of epoxidized soybean oil, trioctyl trimellitate, and polyacrylate plasticizers.

[0024] This invention also provides a method for preparing a PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler, comprising the following steps: A1. Weigh out polypropylene, modified thermally conductive and insulating filler, heat stabilizer, antioxidant, lubricant and plasticizer by weight, and vacuum dry polypropylene and modified thermally conductive and insulating filler at 80-100℃ for 4-8 hours respectively.

[0025] A2. Add the dried polypropylene, heat stabilizer, antioxidant, lubricant and plasticizer to a high-speed mixer and mix for 5-12 minutes at 600-1200 r / min to obtain resin premix.

[0026] A3. The resin premix is ​​added to a co-rotating twin-screw extruder, and the modified thermally conductive and insulating filler is added to the co-rotating twin-screw extruder through the main feed port or the side feed port for melt mixing.

[0027] The temperature of the co-rotating twin-screw extruder from the feeding section to the die head is 165-175℃, 175-185℃, 185-200℃, 195-210℃, and 195-205℃ respectively, the screw speed is 180-420 r / min, and the vacuum degree of the vacuum exhaust is 0.06-0.095 MPa.

[0028] A4. After cooling, drawing, and pelletizing the extrudate after melt mixing, dry it at 80-100℃ for 3-6 hours to obtain PP-based battery cell lead terminal material granules.

[0029] A5. The PP-based battery cell lead terminal material granules are injection molded or extruded at 180-220°C to obtain PP-based battery cell lead terminal material products.

[0030] By adopting the above technical solution, preferably, in step A3, the modified thermally conductive and insulating filler is fed into the co-rotating twin-screw extruder in a segmented feeding manner. 30-50% of the total mass of the modified thermally conductive and insulating filler and the resin premix are added through the main feed port, and the remaining 50-70% are added through the side feed port between the melting section and the mixing section.

[0031] By adopting the above technical solution, preferably, the length-to-diameter ratio of the co-rotating twin-screw extruder is 36:1-48:1, and the melt mixing residence time is 1.5-3.5 min.

[0032] By adopting the above technical solution, preferably, in step A5, when using injection molding, the barrel temperature is 180-220℃, the mold temperature is 40-70℃, the injection pressure is 60-100MPa, the holding pressure is 30-60MPa, and the holding time is 5-20s.

[0033] This invention utilizes spherical α-alumina micropowder, hydroxylated hexagonal boron nitride nanosheets, and silicon nitride whiskers within a polypropylene matrix, which respectively function as point-like thermally conductive nodes, sheet-like thermally conductive bridges, and linear thermally conductive frameworks. These three components interlock to form a point-sheet-line synergistic thermally conductive network, thereby improving the continuity of the heat transfer path. A polydopamine anchoring layer enhances the interfacial bonding between different inorganic fillers and provides active sites. A magnesium-aluminum layered double hydroxide insulating locking layer provides in-situ locking and insulating isolation for the composite thermally conductive framework. A polyphosphazene-siloxane-POSS composite shell improves the heat resistance, barrier properties, and structural stability of the filler surface. A maleic anhydride-grafted polypropylene wax compatibility coating layer improves the interfacial compatibility between the modified filler and the polypropylene matrix. Heat stabilizers, antioxidants, and lubricants respectively enhance the material's thermal processing stability, antioxidant aging resistance, and melt processing fluidity. The synergistic effect of these components results in a PP-based battery cell lead terminal material that maintains electrical insulation and processing performance while also possessing high thermal conductivity, interfacial stability, and long-term service reliability.

[0034] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention constructs a point-sheet-line composite thermally conductive structure using spherical α-alumina micro powder, hydroxylated hexagonal boron nitride nanosheets, and silicon nitride whiskers. This allows thermally conductive and insulating fillers with different morphologies to form a synergistic thermally conductive network within a polypropylene matrix, which is beneficial for improving the thermal conductivity of the material and reducing the problem of discontinuous thermal conductivity pathways in a single filler system.

[0035] 2. This invention improves the interfacial bonding ability between different inorganic fillers through a polydopamine anchoring layer, enabling alumina, boron nitride and silicon nitride whiskers to be more stably combined together, thereby improving the structural stability and dispersion uniformity of the fillers during the mixing process.

[0036] 3. The present invention uses a magnesium-aluminum layered double hydroxide insulating locking layer to surface lock the composite thermally conductive skeleton, which is beneficial to improve the insulation stability of the modified filler and reduce the risk of electrical performance fluctuations caused by direct contact or local agglomeration between thermally conductive fillers.

[0037] 4. This invention improves the heat resistance, barrier properties, and structural stability of the filler surface through a polyphosphazene-siloxane-POSS composite shell, which is beneficial to improving the performance retention rate of PP-based battery cell lead terminal materials in a hot and oxygen environment.

[0038] 5. This invention uses maleic anhydride-grafted polypropylene wax to compatibly coat modified thermally conductive and insulating fillers, thereby improving the interfacial compatibility between the filler and the polypropylene matrix, reducing interfacial thermal resistance, and improving the melt processing performance and mechanical properties of the material.

[0039] 6. The preparation method of the present invention has good process continuity and is applicable to conventional polymer processing processes such as twin-screw extrusion, injection molding or extrusion molding. The resulting material can be used for battery cell lead terminals and their surrounding insulating and heat-conducting structural components. Attached Figure Description

[0040] Figure 1 The images show the SEM image and EDS elemental distribution diagram of the modified thermally conductive and insulating filler prepared in Example 1 of this invention.

[0041] Figure 2 The image shows the XPS full spectrum of the modified thermally conductive and insulating filler prepared in Example 1 of this invention. Detailed Implementation

[0042] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Preparation Example 1 Preparation of modified thermally conductive and insulating fillers: 1. Formula by weight: The composition includes 65 parts of spherical α-alumina micro powder, 18 parts of hydroxylated hexagonal boron nitride nanosheets, 7 parts of silicon nitride whiskers, 6.5 parts of magnesium nitrate hexahydrate, 2.8 parts of aluminum nitrate nonahydrate, 4 parts of urea, 1.8 parts of dopamine hydrochloride, 2 parts of 3-aminopropyltriethoxysilane, 1.2 parts of hexachlorocyclotriphosphazene, 1.0 part of 4,4′-dihydroxydiphenyl sulfone, 1.6 parts of triethylamine, 0.8 parts of 3-mercaptopropyltrimethoxysilane, 0.6 parts of octavinylcage-type silsesquioxane, 3.5 parts of maleic anhydride-grafted polypropylene wax, and 0.07 parts of dicumyl peroxide.

[0044] The spherical α-alumina micro powder, with an α-Al2O3 content of over 90% and a D50 of 5μm, was purchased from Jiangsu Lianrui New Materials Co., Ltd.

[0045] The hydroxylated hexagonal boron nitride nanosheets, with a diameter of 0.1-0.4 μm, were purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0046] The silicon nitride whiskers have a diameter of 0.2-0.7 μm and a length of 10-35 μm, and were purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0047] The octavinyl cage-like silsesquioxane is Sigma-Aldrich 475424.

[0048] The maleic anhydride-grafted polypropylene wax is Clariant Licocene. TM PP MA 6452 granules.

[0049] 2. Preparation method: S1. Spherical α-alumina micro powder and silicon nitride whiskers were added to an anhydrous ethanol / deionized water mixture with a volume ratio of 90:10. The total mass ratio of spherical α-alumina micro powder and silicon nitride whiskers to the mass of the mixture was controlled to be 1:10. 3-aminopropyltriethoxysilane was added, and the pH of the system was adjusted to 4.6 with glacial acetic acid. The reaction was carried out at 60℃ and 750r / min for 3h. After filtration, the mixture was washed three times with anhydrous ethanol and dried under vacuum at 85℃ for 10h to obtain an aminated dot-line framework.

[0050] S2. The aminated dot-line framework and hydroxylated hexagonal boron nitride nanosheets were added to a Tris-HCl buffer solution with a pH of 8.5 and a concentration of 10 mmol / L. The solid-liquid mass ratio was controlled at 1:20. After ultrasonic dispersion for 40 min, the mixture was stirred at 30 °C and 650 r / min. Dopamine hydrochloride was prepared into an aqueous solution with a concentration of 20 mg / mL using deionized water. The solution was added to the dispersion at a dropping rate of 0.8 mL / min and reacted for 6 h. After filtration, the mixture was washed successively with deionized water and anhydrous ethanol, and then vacuum dried at 70 °C for 8 h to obtain the polydopamine-anchored dot-sheet-line precursor.

[0051] S3. The polydopamine-anchored dot-plate-line precursor is dispersed in a deionized water / ethanol mixture with a volume ratio of 70:30, and the solid-liquid mass ratio is controlled at 1:14. Magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and urea are dissolved in a deionized water / ethanol mixture with a volume ratio of 70:30 to prepare a mixed salt solution, and added to the above dispersion at a dropping rate of 1.0 mL / min. During the dropping process, the pH of the system is maintained at 9.5 with 0.5 mol / L sodium hydroxide solution. The mixture is aged at 80℃ and 900 r / min for 4 h, filtered and vacuum dried at 90℃ for 9 h to obtain a magnesium-aluminum layered double hydroxide-locked insulating bridging precursor.

[0052] S4. The insulating bridging precursor is added to anhydrous acetonitrile, and the solid-liquid mass ratio is controlled at 1:20. Under nitrogen protection, hexachlorocyclotriphosphazene, 4,4′-dihydroxydiphenyl sulfone and triethylamine are added. The mixture is pre-reacted at 45°C and 600 r / min for 1.5 h, and then heated to 70°C for 5 h. After filtration, it is washed with anhydrous acetonitrile to obtain the polyphosphazene-coated precursor. The polyphosphazene-coated precursor was dispersed in anhydrous toluene at a solid-liquid mass ratio of 1:18. 3-mercaptopropyltrimethoxysilane, octavinylcage-type silsesquioxane, and dicumyl peroxide were added, and the mixture was reacted at 110°C for 3.5 h under nitrogen protection. After the reaction, the product was dispersed in an ethanol / deionized water mixture at a volume ratio of 90:10. The pH was adjusted to 8.5 with 0.1 mol / L sodium hydroxide solution, and the mixture was reacted at 45°C for 2 h to allow the methoxysilane groups to undergo hydrolysis and condensation. After filtration, the product was washed successively with ethanol and deionized water, and then vacuum dried at 75°C for 12 h to obtain the polyphosphazene-siloxane-POSS composite shell-coated precursor.

[0053] S5. The polyphosphazene-siloxane-POSS composite shell coating precursor and maleic anhydride-grafted polypropylene wax are added to a mixer and melt-coated at 168°C and 80 r / min for 12 min. After cooling, crushing and passing through a 325-mesh sieve, the mixture is vacuum dried at 80°C for 8 h to obtain the modified thermally conductive and insulating filler.

[0054] like Figure 1 As shown in the SEM image, the filler exhibits a composite morphology dominated by spherical particles. Overlapping sheet-like and a small amount of fiber / whisker-like structures are visible between the spherical particles, indicating that the spherical α-Al₂O₃ micropowder, hydroxylated h-BN nanosheets, and Si₃N₄ whiskers can form a point-sheet-line composite thermally conductive framework. In the EDS elemental distribution, Al and O mainly correspond to α-Al₂O₃ and Mg-Al LDH structures, B corresponds to h-BN nanosheets, Si corresponds to Si₃N₄ whiskers and siloxane / POSS structures, Mg corresponds to the Mg-Al LDH insulating interlocking layer, and P corresponds to the polyphosphazene shell. Each element is distributed on the particle surface and in the interparticle regions, indicating that a multi-layered composite modified structure containing elements such as Mg, Al, P, Si, and O has been formed on the surface of the inorganic thermally conductive framework.

[0055] like Figure 2 As shown, characteristic signals related to elements such as O, Al, B, Si, Mg, and P can be observed in the XPS full spectrum, indicating that the sample surface not only contains basic thermally conductive and insulating filler components such as α-Al₂O₃, h-BN, and Si₃N₄, but also surface elements introduced by Mg-Al LDH, polyphosphazene, and the siloxane / POSS composite shell. Combined with the modification route of Preparation Example 1, this full spectrum can be used to demonstrate that multilayer interface modification does not only occur inside the filler, but rather forms a composite coating layer containing magnesium-aluminum, phosphorus-nitrogen, and silicon-oxygen structures on the filler surface, which can be detected by XPS.

[0056] Preparation Example 2 Preparation of modified thermally conductive and insulating fillers: The difference between this preparation example and Preparation Example 1 is that the mass fractions of each raw material and the main process parameters are as follows, while the order of the remaining steps is the same as in Preparation Example 1: 58 parts of spherical α-alumina micro powder, 14 parts of hydroxylated hexagonal boron nitride nanosheets, 5 parts of silicon nitride whiskers, 5 parts of magnesium nitrate hexahydrate, 2 parts of aluminum nitrate nonahydrate, 3 parts of urea, 1.2 parts of dopamine hydrochloride, 1.3 parts of 3-aminopropyltriethoxysilane, 0.8 parts of hexachlorocyclotriphosphazene, 0.7 parts of 4,4′-dihydroxydiphenyl sulfone, 1.0 part of triethylamine, 0.5 parts of 3-mercaptopropyltrimethoxysilane, 0.4 parts of octavinylcage-type silsesquioxane, 2.5 parts of maleic anhydride-grafted polypropylene wax, and 0.04 parts of dicumyl peroxide.

[0057] The solid-liquid mass ratio in S1 was 1:9, the pH was 4.4, the reaction temperature was 58℃, the stirring speed was 650 r / min, the reaction time was 2.5 h, the vacuum drying temperature was 82℃, and the vacuum drying time was 9 h.

[0058] In S2, the pH of the Tris-HCl buffer was 8.4, the solid-liquid mass ratio was 1:18, the mixture was ultrasonically dispersed for 35 min, the reaction temperature was 28℃, the stirring speed was 600 r / min, the dopamine hydrochloride aqueous solution was added at a rate of 0.6 mL / min, and the reaction time was 5 h.

[0059] The solid-liquid mass ratio in S3 is 1:12, the dropping rate of the mixed salt solution is 0.8 mL / min, the pH of the system is 9.3, the aging temperature is 78℃, the stirring speed is 850 r / min, and the aging time is 3.5 h.

[0060] In S4, the solid-liquid mass ratio of the insulating bridging precursor to anhydrous acetonitrile is 1:18, the pre-reaction temperature is 43℃, the pre-reaction time is 1h, the reaction temperature after heating is 68℃, and the reaction time is 4.5h; the polyphosphazene-coated precursor is reacted in anhydrous toluene at 105℃ for 3h, and then hydrolyzed and condensed at pH 8.2 and 42℃ for 1.5h.

[0061] The modified thermally conductive and insulating filler was obtained by melting and coating at a temperature of 162℃, a rotation speed of 70 r / min, and a melting and coating time of 10 min in S5.

[0062] Preparation Example 3 Preparation of modified thermally conductive and insulating fillers: The difference between this preparation example and Preparation Example 1 is that the mass fractions of each raw material and the main process parameters are as follows, while the order of the remaining steps is the same as in Preparation Example 1: 72 parts of spherical α-alumina micro powder, 22 parts of hydroxylated hexagonal boron nitride nanosheets, 9 parts of silicon nitride whiskers, 8 parts of magnesium nitrate hexahydrate, 3.5 parts of aluminum nitrate nonahydrate, 5 parts of urea, 2.5 parts of dopamine hydrochloride, 2.7 parts of 3-aminopropyltriethoxysilane, 1.6 parts of hexachlorocyclotriphosphazene, 1.4 parts of 4,4′-dihydroxydiphenyl sulfone, 2.2 parts of triethylamine, 1.1 parts of 3-mercaptopropyltrimethoxysilane, 0.9 parts of octavinylcage-type silsesquioxane, 4.5 parts of maleic anhydride-grafted polypropylene wax, and 0.10 parts of dicumyl peroxide.

[0063] The solid-liquid mass ratio in S1 is 1:12, the pH is 4.8, the reaction temperature is 64℃, the stirring speed is 850 r / min, the reaction time is 4 h, the vacuum drying temperature is 88℃, and the vacuum drying time is 12 h.

[0064] In S2, the pH of the Tris-HCl buffer was 8.7, the solid-liquid mass ratio was 1:24, the mixture was ultrasonically dispersed for 45 min, the reaction temperature was 35℃, the stirring speed was 800 r / min, the dopamine hydrochloride aqueous solution was added at a rate of 1.0 mL / min, and the reaction time was 8 h.

[0065] The solid-liquid mass ratio in S3 was 1:17, the mixed salt solution was added at a rate of 1.2 mL / min, the pH of the system was 9.7, the aging temperature was 84℃, the stirring speed was 980 r / min, and the aging time was 5 h.

[0066] In S4, the solid-liquid mass ratio of the insulating bridging precursor to anhydrous acetonitrile is 1:24, the pre-reaction temperature is 48℃, the pre-reaction time is 2h, the reaction temperature after heating is 74℃, and the reaction time is 6h; the polyphosphazene-coated precursor is reacted in anhydrous toluene at 115℃ for 4.5h, followed by hydrolysis and condensation at pH 8.8 and 48℃ for 3h.

[0067] The S5 melt coating temperature was 173℃, the rotation speed was 95r / min, and the melt coating time was 15min, resulting in a modified thermally conductive and insulating filler.

[0068] Comparative Preparation Example 1 The modified thermally conductive and insulating filler was prepared by referring to the preparation method in Preparation Example 1, except that the hydroxylated hexagonal boron nitride nanosheets were replaced with unhydroxylated hexagonal boron nitride nanosheets. The unhydroxylated hexagonal boron nitride nanosheets had a diameter of 0.1-0.4 μm and were added in the same amount of 18 parts. Everything else was the same as in Preparation Example 1.

[0069] Comparative Preparation Example 2 The modified thermally conductive and insulating filler was prepared by referring to the preparation method in Preparation Example 1, except that the silicon nitride whiskers were replaced with silicon nitride nanoparticles with a size of 20-50 nm, and the amount added was still 7 parts. Everything else was the same as in Preparation Example 1.

[0070] Among them, silicon nitride nanoparticles are produced by Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0071] Comparative preparation example 3 The modified thermally conductive and insulating filler was prepared according to the preparation method in Preparation Example 1, except that 3-aminopropyltriethoxysilane was replaced with methyltriethoxysilane, and the amount added was still 2 parts; the silanized dot-line skeleton obtained in S1 was further processed according to the subsequent steps of the aminated dot-line skeleton in Preparation Example 1, and everything else remained the same as in Preparation Example 1.

[0072] Comparative preparation example 4 The modified thermally conductive and insulating filler was prepared according to the preparation method in Preparation Example 1, except that the dopamine hydrochloride was replaced with tannic acid, and the amount added was still 1.8 parts. The tannic acid was prepared into an aqueous solution with a concentration of 20 mg / mL using deionized water and added to the dispersion at a dropping rate of 0.8 mL / min. The obtained polyphenol anchoring precursor was further processed according to the subsequent steps of the polydopamine anchoring point-plate-line precursor in Preparation Example 1, and the rest remained the same as in Preparation Example 1.

[0073] Comparative preparation example 5 The modified thermally conductive and insulating filler was prepared according to the preparation method in Preparation Example 1, except that magnesium nitrate hexahydrate was replaced with zinc nitrate hexahydrate, and the amount added was still 6.5 parts. Aluminum nitrate nonahydrate, urea and other components remained unchanged, and everything else was the same as in Preparation Example 1.

[0074] Comparative preparation example 6 The modified thermally conductive and insulating filler was prepared according to the preparation method in Preparation Example 1, except that hexachlorocyclotriphosphazene was replaced with cyanuric chloride, and the amount added was still 1.2 parts; the triazine-coated precursor obtained in S4 was further processed according to the subsequent siloxane-POSS composite shell construction steps of the polyphosphazene-coated precursor in Preparation Example 1, and the rest remained the same as in Preparation Example 1.

[0075] Comparative preparation example 7 The modified thermally conductive and insulating filler was prepared according to the preparation method in Preparation Example 1, except that 4,4′-dihydroxydiphenyl sulfone was replaced with bisphenol A, and the amount added was still 1.0 part. Everything else was the same as in Preparation Example 1.

[0076] Comparative Preparation Example 8 The modified thermally conductive and insulating filler was prepared by referring to the preparation method in Preparation Example 1, except that the octavinyl cage-type silsesquioxane was replaced with vinyltrimethoxysilane, and the amount added was still 0.6 parts, while the rest remained the same as in Preparation Example 1.

[0077] Comparative preparation example 9 The modified thermally conductive and insulating filler was prepared according to the preparation method in Preparation Example 1, except that the maleic anhydride-grafted polypropylene wax was replaced with polypropylene wax, and the amount added was still 3.5 parts. Everything else was the same as in Preparation Example 1.

[0078] Example 1

[0079] Preparation of PP-based battery cell lead terminal materials: 1. Formula by weight: 100 parts of polypropylene, 40 parts of the modified thermally conductive and insulating filler obtained in Preparation Example 1, 0.8 parts of heat stabilizer, 2.0 parts of plasticizer, 0.5 parts of antioxidant, and 0.5 parts of lubricant.

[0080] The heat stabilizer is composed of 0.6 parts of hydrotalcite and 0.2 parts of zinc stearate; The plasticizer is epoxidized soybean oil; The antioxidant is composed of 0.25 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 0.25 parts of tris(2,4-di-tert-butylphenyl) phosphite; The lubricant is ethylene bis-stearamide.

[0081] 2. Preparation method: A1. Weigh out polypropylene, modified thermally conductive and insulating filler, heat stabilizer, plasticizer, antioxidant and lubricant according to the above mass proportions, and vacuum dry polypropylene and modified thermally conductive and insulating filler at 90℃ for 6 hours respectively.

[0082] A2. Add the dried polypropylene, heat stabilizer, antioxidant, lubricant and plasticizer to a high-speed mixer and mix for 8 minutes at 900 r / min to obtain resin premix.

[0083] A3. The resin premix is ​​added to a co-rotating twin-screw extruder. The modified thermally conductive and insulating filler is added to the co-rotating twin-screw extruder in a segmented feeding manner. 40% of the total mass of the modified thermally conductive and insulating filler and the resin premix are added through the main feed port, and the remaining 60% is added through the side feed port between the melting section and the mixing section for melt mixing. The temperatures of the co-rotating twin-screw extruder from the feeding section to the die head are 170℃, 180℃, 195℃, 205℃, and 200℃ respectively. The screw speed is 300 r / min, the vacuum degree is 0.085 MPa, the length-to-diameter ratio is 40:1, and the melt mixing residence time is 2.5 min.

[0084] A4. After cooling, drawing, and pelletizing the extrudate after melt mixing, dry it at 90°C for 4 hours to obtain PP-based battery cell lead terminal material granules.

[0085] A5. The PP-based battery cell lead terminal material granules are injection molded at barrel temperatures of 190°C, 200°C, 210°C and 210°C, mold temperature of 60°C, injection pressure of 80MPa, holding pressure of 45MPa and holding time of 10s to obtain PP-based battery cell lead terminal material products.

[0086] Example 2-Example 3

[0087] The preparation of the PP-based battery cell lead terminal material is the same as in Example 1, except that the modified thermally conductive insulating filler is replaced with the modified thermally conductive insulating filler prepared in Examples 2-3.

[0088] Example 4

[0089] The preparation of PP-based battery cell lead terminal material is carried out according to the preparation method of Example 1, except that the amount of modified thermally conductive insulating filler obtained in Example 1 is adjusted from 40 parts to 25 parts, and the rest is the same as in Example 1.

[0090] Example 5

[0091] The preparation of PP-based battery cell lead terminal material is carried out according to the preparation method of Example 1, except that the amount of modified thermally conductive insulating filler obtained in Example 1 is adjusted from 40 parts to 55 parts, and the rest is the same as in Example 1.

[0092] Comparative Examples 1-9 The preparation of the PP-based battery cell lead terminal material is carried out according to the preparation method of Example 1, except that the modified thermally conductive insulating filler is replaced with the modified thermally conductive insulating filler prepared in Comparative Preparation Examples 1-9, and the rest is the same as in Example 1.

[0093] Comparative Example 10 The preparation of PP-based battery cell lead terminal material follows the preparation method of Example 1, except that the modified thermally conductive insulating filler is replaced with a composite thermally conductive insulating filler without interface modification, and the addition amount remains 40 parts, while other aspects remain the same as in Example 1. The composite thermally conductive insulating filler without interface modification is obtained by adding 65 parts of spherical α-alumina micro powder, 18 parts of hydroxylated hexagonal boron nitride nanosheets and 7 parts of silicon nitride whiskers to a high-speed mixer and dry mixing at 900 r / min for 10 min, without performing the surface modification treatments described in S1-S5.

[0094] Comparative Example 11 The preparation of PP-based battery cell lead terminal material follows the same method as in Example 1, except that no modified thermally conductive insulating filler is added, and everything else remains the same as in Example 1.

[0095] Performance testing: 1. Thermal conductivity test: The thermal conductivity was tested in accordance with GB / T22588-2008, and the data are shown in Table 1.

[0096] 2. Combustion performance test: Vertical combustion performance was tested in accordance with GB / T2408-2021; oxygen index was tested in accordance with GB / T2406.2-2009, and the data are shown in Table 1.

[0097] 3. Oxidation induction time test: The oxidation induction time was tested according to GB / T19466.6-2009, and the data are shown in Table 1.

[0098] 4. Tensile property test: The tensile properties were tested in accordance with GB / T1040.2-2022, and the data are shown in Table 1.

[0099] Table 1. Performance test data of the examples and comparative examples

[0100] Table 1 shows that Example 1 used 40 parts of the modified filler prepared in Example 1. Spherical α-Al2O3 was used as a thermally conductive node, hydroxylated h-BN was used as a sheet-like bridge, and Si3N4 whiskers were used as a linear skeleton. It was modified layer by layer by polydopamine, Mg-Al LDH, polyphosphazene-siloxane-POSS and MAH-g-PP wax. Therefore, the thermal conductivity reached 1.72 W / (m·K), flame retardancy V-0, oxygen index 31.8%, oxidation induction time 54.8 min, heat distortion temperature 128.6℃, while maintaining melt index of 8.2 g / 10 min, tensile strength of 42.8 MPa and elongation at break of 126%.

[0101] In Example 2, the amounts of thermally conductive filler and shell modification components were lower, resulting in a decrease in thermally conductive network density and heat-resistant shell strength. Consequently, the thermal conductivity, oxygen index, OIT, HDT, and strength decreased to 1.48, 30.5%, 47.6 min, 123.4 °C, and 40.7 MPa, respectively. However, the rigidity of the filler was less, and the melt index and elongation increased to 8.9 g / 10 min and 139%, respectively.

[0102] In Example 3, the point-sheet-line skeleton and shell components are enhanced, and the interface anchoring, insulation locking and thermal shielding effects are more complete. Therefore, the thermal conductivity, oxygen index, OIT, HDT and strength are increased to 1.88, 33.1%, 60.3 min, 132.8℃ and 43.9 MPa, respectively. However, the viscosity and rigidity of the system increase, causing the melt index to drop to 7.5 g / 10 min and the elongation to drop to 110%.

[0103] In Example 4, the modified filler was reduced to 25 parts. The thermal conductivity was not fully connected and the flame retardant / insulating shell content was insufficient. Therefore, the thermal conductivity was only 1.12, the flame retardancy was reduced to V-1, the oxygen index was 28.6%, the OIT was 44.9 min, the HDT was 116.9℃, and the strength was 39.7 MPa. However, the proportion of continuous phase in the matrix was high, the melt index was 11.3 g / 10 min, and the elongation was 178%.

[0104] In Example 5, the modified filler was increased to 55 parts, resulting in the densest thermally conductive skeleton. Consequently, the thermal conductivity was 2.16, the oxygen index was 34.2%, and the HDT was 137.5℃, which was still V-0. However, the excessive filler increased the melt viscosity and introduced stress concentration, causing the melt index to drop to 5.6 g / 10 min, the elongation to drop to 83%, and the tensile strength to fall back to 41.5 MPa. The OIT was 56.7 min, indicating that although the high filler content enhanced thermal conductivity and dimensional stability, it was not as conducive to maintaining oxidation resistance as the interface / filler ratio in Example 3.

[0105] In Comparative Example 1, when hydroxylated h-BN was replaced with unhydroxylated h-BN, the anchoring of the sheets to polydopamine / LDH was insufficient, and the sheet bridging was prone to agglomeration. The thermal conductivity, flame retardancy, OIT, HDT, strength and elongation decreased to 1.41, V-1, 42.3 min, 120.1℃, 37.9 MPa and 87%, respectively.

[0106] In Comparative Example 2, Si3N4 nanoparticles were used to replace whiskers. The linear long-range thermal conductivity framework was destroyed, and there was a lack of effective overlap between points and sheets. As a result, the thermal conductivity was further reduced to 1.33, and the melt index was 6.3, the strength was 38.4, and the elongation was 92% due to particle agglomeration.

[0107] Comparative Example 3 uses methyltriethoxysilane instead of APTES, which lacks amino reaction / complexation sites. This results in poor subsequent PDA anchoring and multilayer shell construction, with the largest interface defects. Therefore, the thermal conductivity is 1.29, OIT is 39.7 min, HDT is 117.6℃, strength is 36.7 MPa, and elongation is 76%.

[0108] Comparative Example 4 uses tannic acid instead of dopamine. Although it has polyphenolic effects, the film density and universal adhesion are weaker than PDA. The stability of the thermal network and the shell binding are reduced, as shown by 1.46, V-1, 29.4%, 43.8 min, 121.5℃, 38.1 MPa and 94%.

[0109] Comparative Example 5 uses a Zn-Al system instead of Mg-Al LDH. The layer regularity and interface matching of the insulating locking layer are slightly weaker, so the overall performance is lower than that of Example 1, but it still retains some locking effect. The thermal conductivity is 1.52, OIT is 44.1 min, HDT is 122.1℃, strength is 39.0 MPa, and elongation is 101%.

[0110] In Comparative Example 6, cyanuric chloride was used to replace hexachlorocyclotriphosphazene. The synergistic flame retardancy and char-forming heat insulation capabilities of PN were significantly weakened. Therefore, although the thermal conductivity was still 1.57, the flame retardancy was reduced to V-2, the oxygen index was only 26.8%, and the OIT was 38.5 min.

[0111] Comparative Example 7 uses bisphenol A to replace 4,4′-dihydroxydiphenyl sulfone. The rigidity, polarity and heat resistance contribution of the sulfone group in the shell decreases. Therefore, the thermal conductivity of 1.60 is acceptable, but the oxygen index is 28.9%, OIT is 40.9 min, strength is 38.8 MPa, and flame retardancy is only V-1.

[0112] Comparative Example 8 uses vinyltrimethoxysilane instead of octavinyl POSS, which loses the nano-rigid framework and thermal barrier effect of cage-like POSS. Therefore, the thermal conductivity is 1.55, oxygen index is 28.4%, OIT is 39.4 min, HDT is 121.6℃, and elongation is 99%.

[0113] Comparative Example 9 used ordinary PP wax instead of MAH-g-PP wax. Due to the lack of maleic anhydride polar reaction / compatibility, the peeling and agglomeration of filler at the PP interface were aggravated. The interfacial thermal resistance, melt resistance and stress concentration increased simultaneously, as shown by thermal conductivity of 1.36, OIT 36.8min, HDT 116.8℃, melt index 5.1g / 10min, strength 35.8MPa and elongation 69%.

[0114] Although Comparative Example 10 contains Al2O3 / h-BN / Si3N4 composite filler, it has not undergone interface modification. Filler agglomeration, broken thermal conductivity pathways, flame retardant and heat insulation shell, and compatibility coating are all lacking. Therefore, its thermal conductivity is only 0.98, flame retardancy V-2, oxygen index 24.7%, OIT 30.6min, HDT 112.5℃, melt index 3.8g / 10min, strength 30.9MPa, and elongation 42%.

[0115] Comparative Example 11, without thermally conductive and insulating fillers, has a PP matrix without a thermally conductive network and an inorganic / phosphorus silicon flame-retardant barrier. Therefore, its thermal conductivity is only 0.23, its flame retardancy does not reach V-2, its oxygen index is 18.5%, its OIT is 25.8 min, and its HDT is 92.4℃. However, due to the lack of rigid constraints from fillers, its melt index is 15.2 g / 10 min, its elongation is 302%, and its tensile strength is only 33.4 MPa.

[0116] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler, characterized in that, It is formulated from the following components in parts by weight: 100 parts polypropylene, 20-60 parts modified thermally conductive and insulating filler, 0.1-2 parts heat stabilizer, 0.1-5 parts plasticizer, 0.1-1 parts antioxidant, and 0.1-1 parts lubricant; The modified thermally conductive and insulating filler is prepared from the following raw materials in parts by weight: 55-75 parts spherical α-alumina micro powder, 12-24 parts hydroxylated hexagonal boron nitride nanosheets, 4-10 parts silicon nitride whiskers, 4-9 parts magnesium nitrate hexahydrate, 1.5-4 parts aluminum nitrate nonahydrate, 2-6 parts urea, 1-2.8 parts dopamine hydrochloride, 1-3 parts 3-aminopropyltriethoxysilane, 0.6-1.8 parts hexachlorocyclotriphosphazene, 0.5-1.6 parts 4,4′-dihydroxydiphenyl sulfone, 0.8-2.5 parts triethylamine, 0.4-1.2 parts 3-mercaptopropyltrimethoxysilane, 0.3-1 parts octavinyl cage-like silsesquioxane, 2-5 parts maleic anhydride-grafted polypropylene wax, and 0.02-0.12 parts dicumyl peroxide; The modified thermally conductive and insulating filler is a composite filler composed of spherical α-alumina micropowder, hydroxylated hexagonal boron nitride nanosheets, and silicon nitride whiskers forming a thermally conductive framework. The spherical α-alumina micropowder serves as point-like thermally conductive nodes, the hydroxylated hexagonal boron nitride nanosheets serve as sheet-like thermally conductive bridges, and the silicon nitride whiskers serve as linear thermally conductive frameworks. The surface of the composite filler is sequentially formed with a polydopamine anchoring layer, a magnesium-aluminum layered double hydroxide insulating locking layer, a polyphosphazene-siloxane-POSS composite shell, and a maleic anhydride-grafted polypropylene wax compatible coating layer.

2. The PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler as described in claim 1, characterized in that, The preparation method of the modified thermally conductive and insulating filler includes the following steps: S1. Add spherical α-alumina micro powder and silicon nitride whiskers to anhydrous ethanol / deionized water mixture with a volume ratio of 90:10, control the solid-liquid mass ratio at 1:8-12, add 3-aminopropyltriethoxysilane, adjust the pH to 4.2-5.0 with glacial acetic acid, react at 55-65℃ and 600-900 r / min for 2-4 h, filter, wash with anhydrous ethanol, and vacuum dry at 80-90℃ for 8-12 h to obtain an aminated dot-line framework; S2. The aminated dot-line framework and hydroxylated hexagonal boron nitride nanosheets are added to a Tris-HCl buffer solution with a pH of 8.3-8.8 and a concentration of 10 mmol / L. The solid-liquid mass ratio is controlled at 1:15-25. After ultrasonic dispersion for 30-45 min, the mixture is stirred at 25-35℃ and 500-800 r / min. Dopamine hydrochloride aqueous solution is added at a dropping rate of 0.5-1.0 mL / min. The reaction is carried out for 4-8 h. The mixture is then filtered, washed, and dried to obtain the polydopamine-anchored dot-sheet-line precursor. S3. The polydopamine-anchored dot-plate-line precursor is dispersed in a deionized water / ethanol mixture with a volume ratio of 70:30, and the solid-liquid mass ratio is controlled at 1:10-18 to obtain a precursor dispersion. Magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and urea are prepared into a mixed salt solution and added to the precursor dispersion at a dropping rate of 0.7-1.3 mL / min. During the dropping process, the pH of the system is maintained at 9.2-9.8 with 0.5 mol / L sodium hydroxide solution. The mixture is aged at 75-85℃ and 800-1000 r / min for 3-5 h, filtered and then vacuum dried at 90℃ for 8-10 h to obtain a magnesium-aluminum layered double hydroxide-locked insulating bridging precursor. S4. Add the insulating bridging precursor to anhydrous acetonitrile, controlling the solid-liquid mass ratio to 1:15-25. Under nitrogen protection, add hexachlorocyclotriphosphazene, 4,4′-dihydroxydiphenyl sulfone, and triethylamine. Pre-react at 40-50℃ and 500-700 r / min for 1-2 h, then raise the temperature to 65-75℃ and react for 4-6 h. Filter and wash to obtain the polyphosphazene-coated precursor. Disperse the polyphosphazene-coated precursor in anhydrous toluene or anhydrous xylene, add 3-mercaptopropyltrimethoxysilane, octavinylcage-type silsesquioxane, and dicumyl peroxide. Under atmospheric protection, the reaction was carried out at 100-120℃ for 2-5 hours to allow the mercapto group in 3-mercaptopropyltrimethoxysilane to undergo an addition reaction with the vinyl group in octavinylcage-type silsesquioxane. After the reaction was completed, the product was dispersed in a 90:10 volume ratio ethanol / deionized water mixture, the pH was adjusted to 8.0-9.0, and the reaction was carried out at 40-50℃ for 1-3 hours to allow the methoxysilane group to undergo hydrolysis and condensation. After filtration, the product was washed with ethanol and deionized water in sequence, and then vacuum dried at 70-80℃ for 10-14 hours to obtain a polyphosphazene-siloxane-POSS composite shell-coated precursor. S5. The polyphosphazene-siloxane-POSS composite shell coating precursor and maleic anhydride-grafted polypropylene wax are added to a mixer and melt-coated at 160-175℃ and 60-100r / min for 8-15min. After cooling, crushing and passing through a 325-mesh sieve, the modified thermally conductive and insulating filler is obtained by vacuum drying at 80℃ for 6-10h.

3. The PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler according to claim 1, characterized in that, The D50 of the spherical α-alumina micro powder is 3-8 μm.

4. The PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler according to claim 1, characterized in that, The average diameter of the hydroxylated hexagonal boron nitride nanosheets is 0.1-1.0 μm.

5. The PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler according to claim 1, characterized in that, The diameter of the silicon nitride whiskers is 0.2-1.0 μm.

6. The PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler according to claim 1, characterized in that, The heat stabilizer is one or a combination of at least two of calcium stearate, zinc stearate, hydrotalcite, and pentaerythritol stearate.

7. The PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler according to claim 1, characterized in that, The antioxidant is composed of hindered phenolic antioxidants and phosphite antioxidants, wherein the mass ratio of hindered phenolic antioxidants to phosphite antioxidants is 1:0.5-2. The hindered phenolic antioxidant is one or a combination of at least two of the following: pentaerythritol tetrakis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene. The phosphite antioxidant is one or a combination of at least two of the following: tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, and bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite.

8. The PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler according to claim 1, characterized in that, The lubricant is one or a combination of at least two of the following: ethylene bis-stearamide, polyethylene wax, stearamide, and silicone powder; The plasticizer is one or a combination of at least two of the following: epoxidized soybean oil, trioctyl trimellitate, and polyacrylate plasticizers.

9. A method for preparing a PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler as described in any one of claims 1-8, characterized in that, Includes the following steps: A1. Weigh out polypropylene, modified thermally conductive and insulating filler, heat stabilizer, antioxidant, lubricant and plasticizer by weight, and vacuum dry polypropylene and modified thermally conductive and insulating filler at 80-100℃ for 4-8 hours respectively. A2. Add the dried polypropylene, heat stabilizer, antioxidant, lubricant and plasticizer into a high-speed mixer and mix for 5-12 minutes at 600-1200 r / min to obtain resin premix. A3. The resin premix is ​​added to a co-rotating twin-screw extruder, and the modified thermally conductive and insulating filler is added to the co-rotating twin-screw extruder through the main feed port or the side feed port for melt mixing. The temperature of the co-rotating twin-screw extruder from the feeding section to the die head is 165-175℃, 175-185℃, 185-200℃, 195-210℃, and 195-205℃ respectively; the screw speed is 180-420 r / min; and the vacuum degree of the vacuum exhaust is 0.06-0.095 MPa. A4. After cooling, drawing, and pelletizing the extrudate after melt mixing, dry it at 80-100℃ for 3-6 hours to obtain PP-based battery cell lead terminal material granules. A5. The PP-based battery cell lead terminal material granules are injection molded or extruded at 180-220°C to obtain PP-based battery cell lead terminal material products.

10. The method for preparing PP-based battery cell lead terminal material containing modified insulating and thermally conductive filler according to claim 9, characterized in that, In step A3, the modified thermally conductive and insulating filler is fed into the co-rotating twin-screw extruder in a segmented feeding manner. 30-50% of the total mass of the modified thermally conductive and insulating filler and the resin premix are added through the main feed port, and the remaining 50-70% are added through the side feed port between the melting section and the mixing section. The co-rotating twin-screw extruder has a length-to-diameter ratio of 36:1-48:1 and a melt-mixing residence time of 1.5-3.5 min. In step A5, when using injection molding, the barrel temperature is 180-220℃, the mold temperature is 40-70℃, the injection pressure is 60-100MPa, the holding pressure is 30-60MPa, and the holding time is 5-20s.

Images