A high-temperature-resistant insulating material for new energy batteries and a preparation method thereof

Abstract

The application discloses a high-temperature-resistant insulating material for new energy batteries and a preparation method thereof, and relates to the technical field of high polymer materials.The method comprises the following steps: first, modifying o-cresol formaldehyde epoxy resin with DOPO, and then reacting the modified o-cresol formaldehyde epoxy resin with KH-560 to obtain an active compatibilizer and powderize the active compatibilizer; then, performing surface passivation, silica coating, calcination and titanate coupling treatment on aluminum nitride to obtain an AlN@SiO2 composite filler; then, performing surface modification on the filler by using an aminated hyperbranched polysiloxane and nano boron nitride to construct an interface buffer layer; finally, blending, extruding and heat-treating polyetherimide, the active compatibilizer, the modified filler and an antioxidant. The method is suitable for the insulating field of new energy batteries, and the high-temperature stability and long-term heat cycle performance of the material are significantly improved through multi-scale synergistic modification.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a high-temperature resistant insulating material for new energy batteries and its preparation method. Background Technology

[0002] As new energy batteries rapidly iterate towards higher voltage, higher energy density, and longer cycle life, the Joule heat and polarization heat generated during operation increase significantly. Furthermore, the increasing integration of battery packs limits heat dissipation pathways, resulting in the battery's internal components and surrounding area being in a consistently high-temperature environment. Insulating materials, as core protective components of new energy battery systems, directly determine the battery's operational safety, lifespan, and risk mitigation capabilities under extreme conditions. Therefore, stringent requirements are placed on the high-temperature stability, insulation performance retention rate at high temperatures, and thermomechanical reliability of insulating materials.

[0003] Polyetherimide (PEI), a high-performance specialty engineering plastic, has garnered significant attention in the field of insulating materials for new energy batteries due to its superior inherent properties. Compared to traditional materials such as epoxy resins and polyamides, it exhibits greater service potential in medium- and high-temperature environments, making it one of the preferred substrates for high-requirement battery insulation components (such as shell insulating coatings, separators, and terminal sheaths). Furthermore, PEI possesses excellent processing compatibility and can be compounded with inorganic insulating fillers and flame retardants to further expand its performance boundaries. Therefore, it is considered by the industry as one of the core substrates for solving the high-temperature insulation challenges of new energy batteries.

[0004] However, under the increasingly demanding high-temperature operating conditions of new energy batteries, the high-temperature resistance of existing PEI-based insulating materials still has significant room for improvement, making it difficult to fully meet the needs of practical applications. Specifically, this manifests in the following ways: First, the problem of thermal oxidation degradation under long-term high temperatures is prominent. The imide bonds in the PEI molecular chain are prone to slow thermal oxidation breakage under the synergistic effects of temperatures above 150°C, oxygen, and trace amounts of moisture. This leads to molecular chain segment degradation, a decrease in cross-linking density, and consequently, a significant decrease in the material's volume resistivity and dielectric strength. The insulation protection function gradually fails, severely affecting the long-term operational stability of the battery system. Second, insufficient interfacial compatibility and structural stability at high temperatures. To improve insulation performance and thermal conductivity, PEI-based materials typically require composite fillers such as aluminum nitride and silicon dioxide. However, the rigidity of the PEI molecular chain weakens the interfacial bonding between it and the inorganic fillers. Under long-term high-temperature conditions, micro-gaps can easily form at the interface due to the mismatch in thermal expansion coefficients, creating charge migration channels and heat accumulation points. This not only reduces the insulation barrier performance of the material but may also exacerbate local overheating, accelerating overall material failure. Thirdly, its thermomechanical properties are insufficient at extreme high temperatures. When exposed to extreme temperatures above 200°C, although PEI does not undergo significant thermal decomposition, it will exhibit significant thermal creep and dimensional deformation due to its glass transition temperature approaching or exceeding its temperature. This leads to a decrease in the adhesion between the insulating material and battery components, and even peeling and cracking, resulting in a loss of physical protection and insulation isolation functions, creating hidden dangers for battery short circuits, fires, and other safety accidents. Fourthly, its high-temperature resistance and flame retardant synergy are lacking. PEI itself has a certain degree of self-extinguishing properties, but in the early stages of high-temperature thermal runaway, its flame retardant efficiency is limited, and it is prone to burning and dripping. This can not only lead to the complete loss of insulation function, but may also promote the spread of flames and increase safety risks. Summary of the Invention

[0005] The purpose of this invention is to provide a high-temperature resistant insulating material for new energy batteries and its preparation method, so as to solve the technical problem mentioned in the background art that the high-temperature resistance of polyetherimide insulating materials needs to be improved.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a high-temperature resistant insulating material for new energy batteries includes the following steps:

[0008] (1) Mix o-cresol epoxy resin, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and catalyst, and react under nitrogen protection to obtain phosphorus-modified epoxy resin.

[0009] (2) Add an accelerator and γ-glycidoxypropyltrimethoxysilane to the phosphorus-modified epoxy resin and react under vacuum to obtain an active compatibilizer.

[0010] (3) Cool and pulverize the active compatibilizer product and mix it with fumed silica to obtain active compatibilizer powder;

[0011] (4) Disperse aluminum nitride powder in anhydrous isopropanol, add silane coupling agent for surface treatment; then add tetraethyl orthosilicate and ammonia water dropwise to the system at the same time to carry out silica coating reaction to obtain the coated filler;

[0012] (5) The coated filler was calcined under a nitrogen atmosphere, then dispersed in anhydrous toluene, and a titanate coupling agent was added for reflux reaction to obtain a surface-modified composite filler.

[0013] (6) Aminated hyperbranched polysiloxane and nano-hexagonal boron nitride were added to anhydrous toluene and ultrasonically dispersed to obtain a modified solution;

[0014] (7) The surface-modified composite filler was added to the modified liquid and refluxed. Then the solvent was removed and the mixture was dried to obtain the reinforced composite filler.

[0015] (8) The polyetherimide, active compatibilizer powder, reinforcing composite filler and antioxidant are dry mixed at high speed, and then melt extrusion granulation and heat treatment are carried out to obtain the product.

[0016] In this invention, the high-temperature resistance of polyetherimide insulating materials is improved synergistically from the following aspects: Firstly, by constructing a highly heat-resistant and highly compatible active compatibilizer system, the high-temperature resistance of the material is enhanced from the perspective of matrix strengthening. Firstly, o-cresyl epoxy resin, which inherently possesses high crosslinking density and high thermal decomposition temperature, is selected as the base. Its thermal stability far exceeds that of ordinary bisphenol A epoxy, perfectly matching the high-temperature processing window of polyetherimide (PEI) and providing an excellent heat-resistant foundation for the system. Secondly, the introduction of phosphorus not only imparts inherent flame retardancy to the matrix but also further enhances the rigidity of the molecular chain through the construction of multifunctional branch chains, inhibiting the relaxation and degradation of the molecular chain at high temperatures. Grafting of organosilicon units improves the wettability of compatibilizers and inorganic fillers, preventing gaps and heat accumulation between fillers and the matrix due to weak interfacial bonding at high temperatures. Simultaneously, viscosity-controlled reaction prevents premature gelation of the prepolymer, ensuring the stability of the processing. Cryogenic pulverization and anti-caking treatment ensure that the compatibilizer exists in a free-flowing powder form, enabling it to achieve molecular-level uniform mixing and in-situ grafting with PEI. This avoids weak high-temperature resistance areas caused by uneven local components. Ultimately, through the high heat resistance of the compatibilizer and its synergistic compatibility with PEI and fillers, the high-temperature structural stability, thermal oxidation resistance, and processing compatibility of the matrix are significantly improved, providing core support for the overall high-temperature performance of the material.

[0017] On the other hand, by constructing a core-shell composite filler with stable structure and synergistic function, the high-temperature resistance of the material is improved through physical reinforcement and interface optimization. After anhydrous passivation treatment, the AlN core layer shields water-sensitive sites, avoiding structural defects caused by hydrolysis. Its excellent high thermal conductivity can quickly conduct local heat generated by the material under high-temperature conditions, reducing local overheating degradation caused by heat accumulation. The deposited SiO2 shell layer is continuous, dense and uniform. SiO2 itself has good high-temperature stability, forming a physical protective barrier to prevent external heat from being quickly conducted into the matrix, while also preventing the AlN core layer from oxidizing and deteriorating at high temperatures. High-temperature ceramic calcination under a nitrogen atmosphere eliminates some of the hydroxyl groups and structural defects in the SiO2 shell, preventing the volatilization of hydroxyl groups at high temperatures that could generate bubbles or cause shell rupture, thus further enhancing the high-temperature stability of the core-shell structure. The titanate coupling treatment in a non-polar system forms a strong organic-friendly monolayer on the filler surface, significantly improving the interfacial bonding between the filler and the PEI matrix, while also increasing the filler's filling limit. This allows the filler to form a continuous heat-resistant and thermally conductive network within the matrix, working in conjunction with the matrix to achieve rapid heat diffusion and structural stability, thereby significantly improving the structural integrity and performance stability of the material under long-term high-temperature and extreme high-temperature conditions.

[0018] Preferably, in step (1), the mass ratio of o-cresol epoxy resin to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 10:(1.4-1.6).

[0019] Preferably, in step (2), the mass ratio of phosphorus-modified epoxy resin to γ-glycidyl etheroxypropyltrimethoxysilane is 10:(0.5-1.0).

[0020] Preferably, in step (3), the amount of fumed silica added is 1 to 3 wt% of the active compatibilizer product.

[0021] Preferably, in step (4), the silane coupling agent is KH-550 silane coupling agent;

[0022] The mass ratio of the aluminum nitride powder to the silane coupling agent is 20:(1-3).

[0023] Preferably, in step (4), the mass ratio of aluminum nitride powder to tetraethyl orthosilicate is 20:(6-10).

[0024] Preferably, in step (6), the mass ratio of aminated hyperbranched polysiloxane to nano-hexagonal boron nitride is 3:(1-2).

[0025] This invention, through experiments, discovered that although phosphorus-silicon modification improves the heat resistance and density of the epoxy resin matrix, and the construction of an AlN@SiO2 core-shell structure significantly enhances the insulation and thermal conductivity of the filler, a key synergistic problem arises when these two components are combined: due to the significant difference in thermal expansion coefficients between the active solubilizer epoxy matrix and the AlN@SiO2 filler, microcracks or even delamination occur at the interface due to thermal stress mismatch under frequent thermal cycling caused by battery charging and discharging. This "rigid delamination" not only drastically increases interfacial thermal resistance leading to heat dissipation failure, but also forms micro-gaps at the interface, becoming the starting point of corona discharge, causing long-term high-temperature performance failure of the material and seriously threatening the long-term insulation reliability of the material. To solve the above-mentioned interfacial thermal stress problem, this invention introduces aminated hyperbranched polysiloxane (NH2-HBPSi) and nano-hexagonal boron nitride (h-BN) to construct a buffer layer. Specifically, the active amino groups at the ends of NH2-HBPSi are first chemically bonded to the surface of AlN@SiO2 filler, thus coating the filler. The unique hyperbranched three-dimensional structure of NH2-HBPSi endows it with high elasticity and a large free volume, acting like a nanospring to form a flexible stress buffer layer between the rigid filler and the rigid matrix. This effectively absorbs and dissipates the mechanical energy generated by uneven thermal expansion and contraction, transforming brittle hard contacts into tough soft connections. Simultaneously, the high specific surface area of ​​NH2-HBPSi effectively adsorbs and disperses h-BN nanosheets, ensuring their uniform distribution at the filler interface. During subsequent melt blending, these h-BN nanosheets bridge the gaps between large AlN@SiO2 particles, filling thermally conductive voids and forming a highly efficient secondary thermally conductive network. Furthermore, their excellent electrical insulation properties constitute an additional insulating barrier at the interface, blocking conductive pathways even if microcracks initiate, achieving path shielding. Ultimately, the stress buffering effect of NH2-HBPSi and the thermal conductivity-insulation enhancement effect of h-BN were synergistically achieved, fundamentally solving the interfacial thermal fatigue problem and realizing the long-term performance stability of the material under extreme temperature cycling, thereby improving the long-term high-temperature resistance of polyetherimide insulation materials.

[0026] Preferably, in step (8), the mass ratio of polyetherimide to active compatibilizer powder is 100:(5-8).

[0027] Preferably, in step (8), the mass ratio of polyetherimide to reinforced composite filler is 100:(35-40).

[0028] A high-temperature resistant insulating material for new energy batteries is prepared by the method described above.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. Through the synergistic effect of phosphorus-silicon synergistic modification of high heat-resistant compatibilizer and stable core-shell filler, the material can maintain excellent insulation performance and structural integrity in high-temperature environments, meeting the extreme operating conditions requirements of new energy batteries.

[0031] 2. The introduced flexible buffer layer (NH2-HBPSi) and secondary thermal conductive network (h-BN) can effectively absorb and dissipate the stress generated by thermal cycling, prevent microcracks or peeling at the interface, and thus greatly improve the long-term reliability and lifespan of the material under frequent temperature shocks. Attached Figure Description

[0032] Figure 1 This is a SEM image of the cross-section of the high-temperature resistant insulating material for new energy batteries prepared in Example 4 of the present invention.

[0033] Figure 2 XPS spectrum of the high-temperature resistant insulating material for new energy batteries prepared in Example 4 of this invention. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] A method for preparing a high-temperature resistant insulating material for new energy batteries includes the following steps:

[0037] Step 1: Add 100g of o-cresphenolic epoxy resin to a three-necked flask, heat to 140℃ to melt it, purge with nitrogen for protection, add 15.5g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 0.1g of tetraphenylphosphine bromide catalyst, heat to 165℃ and stir continuously for 4h to obtain phosphorus-modified epoxy resin.

[0038] Step 2: Cool the system to 130℃, add 0.12g benzyl dimethylamine accelerator to 100g phosphorus-modified epoxy resin, turn on the vacuum device and maintain the vacuum degree at -0.05MPa, slowly add 9g γ-glycidoxypropyltrimethoxysilane at a rate of 1mL / min, and maintain the constant temperature reaction for 3h to obtain the active compatibilizer.

[0039] Step 3: Pour out the above active compatibilizer product, cool and solidify it at room temperature, place it in a liquid nitrogen-assisted cryogenic crusher to pulverize it, and then add fumed silica at 2.5 wt% of the active compatibilizer product mass. Mix it evenly in a ball mill to obtain active compatibilizer powder.

[0040] Step 4: Disperse 20g of aluminum nitride powder in 400mL of anhydrous isopropanol and ultrasonically disperse for 60min. Add 2.5g of KH-550 silane coupling agent and stir at 65℃ for 5h for surface treatment. Then adjust the system temperature to 45℃ and use a peristaltic pump to simultaneously add 9g of tetraethyl orthosilicate and 4.5mL of 15% ammonia solution to the system at a rate of 0.5mL / min. Continue stirring for 15h to carry out the silica coating reaction and obtain the coated filler.

[0041] Step 5: Filter and dry the coated filler, place it in a tube furnace, and calcine it at a rate of 5℃ / min to 500℃ under continuous high-purity nitrogen gas. After cooling, redisperse the calcined filler in 250mL of anhydrous toluene, add 1.5g of titanate coupling agent KR-TTS, and reflux at 90℃ for 4h to obtain the surface-modified composite filler.

[0042] Step 6: Add 3g of aminated hyperbranched polysiloxane and 1.8g of nano-hexagonal boron nitride to 200mL of anhydrous toluene, and perform ultrasonic dispersion treatment at 500W power for 2h to obtain the modified solution.

[0043] Step 7: Slowly add the above surface-modified composite filler into the modification solution, heat to 110℃ and reflux for 4 hours; after the reaction is completed, remove the solvent using a rotary evaporator and dry to obtain the reinforced composite filler.

[0044] Step 8: By weight, add 100 parts of polyetherimide powder, 7 parts of active compatibilizer powder, 39 parts of reinforcing composite filler, and 0.6 parts of antioxidant 1010 to a high-speed cold mixer and dry mix at 2800 r / min for 15 min. Feed the mixed material into a co-rotating twin-screw extruder and set the section temperatures to 260℃, 295℃, 320℃, 330℃, 325℃, and 310℃. Open the vacuum exhaust port with a vacuum degree of -0.095MPa and melt extrude granulation at a screw speed of 350 r / min. Place the resulting granules in a vacuum oven and treat them first at 160℃ for 2 h, then raise the temperature to 225℃ for 4 h, and finally cool them slowly in the oven to obtain the final product.

[0045] Example 2

[0046] A method for preparing a high-temperature resistant insulating material for new energy batteries includes the following steps:

[0047] Step 1: Add 100g of o-cresphenolic epoxy resin to a three-necked flask, heat to 140℃ to melt it, purge with nitrogen for protection, add 14.5g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 0.1g of tetraphenylphosphine bromide catalyst, heat to 165℃ and stir continuously for 4h to obtain phosphorus-modified epoxy resin.

[0048] Step 2: Cool the system to 130℃, add 0.12g benzyl dimethylamine accelerator to 100g phosphorus-modified epoxy resin, turn on the vacuum device and maintain the vacuum degree at -0.05MPa, slowly add 6g γ-glycidoxypropyltrimethoxysilane at a rate of 1mL / min, and maintain the constant temperature reaction for 3h to obtain the active compatibilizer.

[0049] Step 3: Pour out the above active compatibilizer product, cool and solidify it at room temperature, place it in a liquid nitrogen-assisted cryogenic crusher to pulverize it, and then add 1.5 wt% of fumed silica according to the mass of the active compatibilizer product. Mix it evenly in a ball mill to obtain active compatibilizer powder.

[0050] Step 4: Disperse 20g of aluminum nitride powder in 400mL of anhydrous isopropanol, ultrasonically disperse for 60min, add 1.5g of KH-550 silane coupling agent, and stir at 65℃ for 5h for surface treatment; then adjust the system temperature to 45℃, and simultaneously add 7g of tetraethyl orthosilicate and 4.5mL of 15% ammonia solution to the system at a rate of 0.5mL / min using a peristaltic pump, and continue stirring for 15h to carry out the silica coating reaction, and obtain the coated filler.

[0051] Step 5: Filter and dry the coated filler, place it in a tube furnace, and calcine it at a rate of 5℃ / min to 500℃ under continuous high-purity nitrogen gas. After cooling, redisperse the calcined filler in 250mL of anhydrous toluene, add 1.5g of titanate coupling agent KR-TTS, and reflux at 90℃ for 4h to obtain the surface-modified composite filler.

[0052] Step 6: Add 3g of aminated hyperbranched polysiloxane and 1.2g of nano-hexagonal boron nitride to 200mL of anhydrous toluene, and perform ultrasonic dispersion treatment at 500W power for 2h to obtain the modified solution.

[0053] Step 7: Slowly add the above surface-modified composite filler into the modification solution, heat to 110℃ and reflux for 4 hours; after the reaction is completed, remove the solvent using a rotary evaporator and dry to obtain the reinforced composite filler.

[0054] Step 8: By weight, add 100 parts of polyetherimide powder, 6 parts of active compatibilizer powder, 36 parts of reinforcing composite filler, and 0.6 parts of antioxidant 1010 to a high-speed cold mixer and dry mix at 2800 r / min for 15 min. Feed the mixed material into a co-rotating twin-screw extruder and set the section temperatures to 260℃, 295℃, 320℃, 330℃, 325℃, and 310℃. Open the vacuum exhaust port with a vacuum degree of -0.095MPa and melt extrude granulation at a screw speed of 350 r / min. Place the resulting granules in a vacuum oven and treat them first at 160℃ for 2 h, then raise the temperature to 225℃ for 4 h, and finally slowly cool them in the oven to obtain the final product.

[0055] Example 3

[0056] A method for preparing a high-temperature resistant insulating material for new energy batteries includes the following steps:

[0057] Step 1: Add 100g of o-cresol epoxy resin to a three-necked flask, heat to 140℃ to melt it, purge with nitrogen for protection, add 15g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 0.1g of tetraphenylphosphine bromide catalyst, heat to 165℃ and stir continuously for 4h to obtain phosphorus-modified epoxy resin.

[0058] Step 2: Cool the system to 130℃, add 0.12g benzyl dimethylamine accelerator to 100g phosphorus-modified epoxy resin, turn on the vacuum device and maintain the vacuum degree at -0.05MPa, slowly add 7g γ-glycidoxypropyltrimethoxysilane at a rate of 1mL / min, and maintain the constant temperature reaction for 3h to obtain the active compatibilizer.

[0059] Step 3: Pour out the above active compatibilizer product, cool and solidify it at room temperature, place it in a liquid nitrogen-assisted cryogenic crusher to pulverize it, and then add fumed silica at 2wt% of the mass of the active compatibilizer product. Mix it evenly in a ball mill to obtain active compatibilizer powder.

[0060] Step 4: Disperse 20g of aluminum nitride powder in 400mL of anhydrous isopropanol and ultrasonically disperse for 60min. Add 2g of KH-550 silane coupling agent and stir at 65℃ for 5h for surface treatment. Then adjust the system temperature to 45℃ and use a peristaltic pump to simultaneously add 8g of tetraethyl orthosilicate and 4.5mL of 15% ammonia solution to the system at a rate of 0.5mL / min. Continue stirring for 15h to carry out the silica coating reaction and obtain the coated filler.

[0061] Step 5: Filter and dry the coated filler, place it in a tube furnace, and calcine it at a rate of 5℃ / min to 500℃ under continuous high-purity nitrogen gas. After cooling, redisperse the calcined filler in 250mL of anhydrous toluene, add 1.5g of titanate coupling agent KR-TTS, and reflux at 90℃ for 4h to obtain the surface-modified composite filler.

[0062] Step 6: Add 3g of aminated hyperbranched polysiloxane and 1.5g of nano-hexagonal boron nitride to 200mL of anhydrous toluene, and perform ultrasonic dispersion treatment at 500W power for 2h to obtain the modified solution.

[0063] Step 7: Slowly add the above surface-modified composite filler into the modification solution, heat to 110℃ and reflux for 4 hours; after the reaction is completed, remove the solvent using a rotary evaporator and dry to obtain the reinforced composite filler.

[0064] Step 8: By weight, add 100 parts of polyetherimide powder, 6.5 parts of active compatibilizer powder, 38 parts of reinforcing composite filler, and 0.6 parts of antioxidant 1010 to a high-speed cold mixer and dry mix at 2800 r / min for 15 min. Feed the mixed material into a co-rotating twin-screw extruder and set the section temperatures to 260℃, 295℃, 320℃, 330℃, 325℃, and 310℃. Open the vacuum exhaust port with a vacuum degree of -0.095MPa and melt extrude granulation at a screw speed of 350 r / min. Place the resulting granules in a vacuum oven and treat them first at 160℃ for 2 h, then raise the temperature to 225℃ for 4 h, and finally slowly cool them in the oven to obtain the final product.

[0065] Example 4

[0066] A method for preparing a high-temperature resistant insulating material for new energy batteries includes the following steps:

[0067] Step 1: Add 100g of o-cresol epoxy resin to a three-necked flask, heat to 140℃ to melt it, purge with nitrogen for protection, add 16g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 0.1g of tetraphenylphosphine bromide catalyst, heat to 165℃ and stir continuously for 4h to obtain phosphorus-modified epoxy resin.

[0068] Step 2: Cool the system to 130℃, add 0.12g benzyl dimethylamine accelerator to 100g phosphorus-modified epoxy resin, turn on the vacuum device and maintain the vacuum degree at -0.05MPa, slowly add 10g γ-glycidoxypropyltrimethoxysilane at a rate of 1mL / min, and maintain the constant temperature reaction for 3h to obtain the active compatibilizer.

[0069] Step 3: Pour out the above active compatibilizer product, cool and solidify it at room temperature, place it in a liquid nitrogen-assisted cryogenic crusher to pulverize it, and then add 3wt% of fumed silica according to the mass of the active compatibilizer product. Mix it evenly in a ball mill to obtain active compatibilizer powder.

[0070] Step 4: Disperse 20g of aluminum nitride powder in 400mL of anhydrous isopropanol and ultrasonically disperse for 60min. Add 3g of KH-550 silane coupling agent and stir at 65℃ for 5h for surface treatment. Then adjust the system temperature to 45℃ and use a peristaltic pump to simultaneously add 10g of tetraethyl orthosilicate and 4.5mL of 15% ammonia solution to the system at a rate of 0.5mL / min. Continue stirring for 15h to carry out the silica coating reaction and obtain the coated filler.

[0071] Step 5: Filter and dry the coated filler, place it in a tube furnace, and calcine it at a rate of 5℃ / min to 500℃ under continuous high-purity nitrogen gas. After cooling, redisperse the calcined filler in 250mL of anhydrous toluene, add 1.5g of titanate coupling agent KR-TTS, and reflux at 90℃ for 4h to obtain the surface-modified composite filler.

[0072] Step 6: Add 3g of aminated hyperbranched polysiloxane and 2g of nano-hexagonal boron nitride to 200mL of anhydrous toluene, and perform ultrasonic dispersion treatment at 500W power for 2h to obtain the modified solution.

[0073] Step 7: Slowly add the above surface-modified composite filler into the modification solution, heat to 110℃ and reflux for 4 hours; after the reaction is completed, remove the solvent using a rotary evaporator and dry to obtain the reinforced composite filler.

[0074] Step 8: By weight, add 100 parts of polyetherimide powder, 8 parts of active compatibilizer powder, 40 parts of reinforcing composite filler, and 0.6 parts of antioxidant 1010 to a high-speed cold mixer and dry mix at 2800 r / min for 15 min. Feed the mixed material into a co-rotating twin-screw extruder and set the section temperatures to 260℃, 295℃, 320℃, 330℃, 325℃, and 310℃. Open the vacuum exhaust port with a vacuum degree of -0.095MPa and melt extrude granulation at a screw speed of 350 r / min. Place the resulting granules in a vacuum oven and treat them first at 160℃ for 2 h, then raise the temperature to 225℃ for 4 h, and finally slowly cool them in the oven to obtain the final product.

[0075] Example 5

[0076] A method for preparing a high-temperature resistant insulating material for new energy batteries includes the following steps:

[0077] Step 1: Add 100g of o-cresphenolic epoxy resin to a three-necked flask, heat to 140℃ to melt it, purge with nitrogen for protection, add 14g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 0.1g of tetraphenylphosphine bromide catalyst, heat to 165℃ and stir continuously for 4h to obtain phosphorus-modified epoxy resin.

[0078] Step 2: Cool the system to 130℃, add 0.12g benzyl dimethylamine accelerator to 100g phosphorus-modified epoxy resin, turn on the vacuum device and maintain the vacuum degree at -0.05MPa, slowly add 5g γ-glycidoxypropyltrimethoxysilane at a rate of 1mL / min, and maintain the constant temperature reaction for 3h to obtain the active compatibilizer.

[0079] Step 3: Pour out the above active compatibilizer product, cool and solidify it at room temperature, place it in a liquid nitrogen-assisted cryogenic crusher to pulverize it, and then add fumed silica at 1 wt% of the mass of the active compatibilizer product. Mix it evenly in a ball mill to obtain active compatibilizer powder.

[0080] Step 4: Disperse 20g of aluminum nitride powder in 400mL of anhydrous isopropanol, ultrasonically disperse for 60min, add 1g of KH-550 silane coupling agent, and stir at 65℃ for 5h for surface treatment; then adjust the system temperature to 45℃, and simultaneously add 6g of tetraethyl orthosilicate and 4.5mL of 15% ammonia solution to the system at a rate of 0.5mL / min using a peristaltic pump, and continue stirring for 15h to carry out the silica coating reaction, and obtain the coated filler.

[0081] Step 5: Filter and dry the coated filler, place it in a tube furnace, and calcine it at a rate of 5℃ / min to 500℃ under continuous high-purity nitrogen gas. After cooling, redisperse the calcined filler in 250mL of anhydrous toluene, add 1.5g of titanate coupling agent KR-TTS, and reflux at 90℃ for 4h to obtain the surface-modified composite filler.

[0082] Step 6: Add 3g of aminated hyperbranched polysiloxane and 1g of nano-hexagonal boron nitride to 200mL of anhydrous toluene, and perform ultrasonic dispersion treatment at 500W power for 2h to obtain the modified solution.

[0083] Step 7: Slowly add the above surface-modified composite filler into the modification solution, heat to 110℃ and reflux for 4 hours; after the reaction is completed, remove the solvent using a rotary evaporator and dry to obtain the reinforced composite filler.

[0084] Step 8: By weight, add 100 parts of polyetherimide powder, 5 parts of active compatibilizer powder, 35 parts of reinforcing composite filler, and 0.6 parts of antioxidant 1010 to a high-speed cold mixer and dry mix at 2800 r / min for 15 min. Feed the mixed material into a co-rotating twin-screw extruder and set the section temperatures to 260℃, 295℃, 320℃, 330℃, 325℃, and 310℃. Open the vacuum exhaust port with a vacuum degree of -0.095MPa and melt extrude granulation at a screw speed of 350 r / min. Place the resulting granules in a vacuum oven and treat them first at 160℃ for 2 h, then raise the temperature to 225℃ for 4 h, and finally slowly cool them in the oven to obtain the final product.

[0085] Comparative Example 1: The difference between Comparative Example 1 and Example 4 is that steps 1-3 are omitted, and no active compatibilizer powder is added in step 8.

[0086] Comparative Example 2: The difference between Comparative Example 2 and Example 4 is that steps 4-7 are omitted, and the reinforcing composite filler in step 8 is replaced with an equal mass of aluminum nitride powder.

[0087] Comparative Example 3: The difference between Comparative Example 3 and Example 4 is that steps 6-7 are omitted, and the reinforcing composite filler in step 8 is replaced with the surface-modified composite filler obtained in step 5. That is, the surface-modified composite filler is not treated with aminated hyperbranched polysiloxane and nano-hexagonal boron nitride.

[0088] Comparative Example 4: The difference between Comparative Example 4 and Example 4 is that aminated hyperbranched polysiloxane is not added in step 6.

[0089] Comparative Example 5: The difference between Comparative Example 5 and Example 4 is that nano-hexagonal boron nitride is not added in step 6.

[0090] Performance testing:

[0091] 1. Volume Resistivity Test: The volume resistivity and surface resistivity of solid insulating materials were measured using a high-resistivity meter, referring to GB / T 1410-2006 "Test Methods for Volume Resistivity and Surface Resistivity of Solid Insulating Materials". The materials prepared in the examples and comparative examples were pressed into circular samples with a diameter of 100 mm and a thickness of 2 mm. A DC voltage of 500 V was applied at both room temperature (25℃) and high temperature (200℃), and the stabilized resistance values ​​were read and converted to volume resistivity. This index is used to evaluate the basic electrical insulation performance of the material under normal and extreme high-temperature service conditions. The test results are shown in Table 1.

[0092] 2. Dielectric Strength (Breakdown Voltage) Test: The test was conducted using the continuous voltage ramp method, referring to GB / T 1408.1-2016 "Test Methods for Electrical Strength of Insulating Materials". The sample was placed in transformer oil to prevent surface flashover. Cylindrical electrodes of uniform diameter (25 mm) were used. The voltage ramp rate was set to 1 kV / s. The voltage value at the moment of breakdown was recorded, and the breakdown strength per unit thickness (kV / mm) was calculated. This indicator directly reflects the material's ability to resist damage from a high-voltage electric field. The test results are shown in Table 1.

[0093] 3. Glass transition temperature (Tg) test: The Tg was measured using differential scanning calorimetry (DSC). Under a nitrogen atmosphere, the temperature was increased from room temperature to 300℃ at a pressurization rate of 10℃ / min. The temperature corresponding to the midpoint of the step change in the second heating curve or the peak value of the loss tangent (tanδ) was taken as the glass transition temperature. The magnitude of Tg directly determines the thermomechanical reliability and dimensional stability of the material at high temperatures. The test results are shown in Table 1.

[0094] 4. Thermal conductivity test: Following GB / T 22588-2008 "Evaluation of thermal diffusivity and thermal conductivity by flash method", a laser thermal conductivity meter was used for testing. The sample was processed into a circular disc with a diameter of 12.7 mm and a thickness of approximately 1 mm, and its thermal conductivity was measured at 25℃. This indicator is used to evaluate the material's ability to dissipate heat accumulated inside the cell; a higher thermal conductivity is more beneficial for reducing heat accumulation at the interface. The test results are shown in Table 1.

[0095] 5. Thermal Shock Cycling Performance (Key Reliability Test): The sample was placed in a thermal shock test chamber and subjected to extreme temperature cycling from -40℃ (30 min) to 200℃ (30 min). After 100 cycles, the sample was removed and the surface was observed for microcracks or peeling. The dielectric strength at 200℃ was then retested. The dielectric strength retention rate before and after cycling was calculated. This indicator is specifically used to evaluate the actual effectiveness of the NH2-HBPSi buffer layer in this invention in solving the problems of "interfacial thermal stress mismatch" and "rigid peeling". The test results are shown in Table 1.

[0096] Table 1:

[0097]

[0098] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-temperature resistant insulating material for new energy batteries, characterized in that, Includes the following steps: (1) Mix o-cresol epoxy resin, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and catalyst, with the mass ratio of o-cresol epoxy resin to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide being 10:(1.4~1.6), and react under nitrogen protection to obtain phosphorus-modified epoxy resin; (2) Add an accelerator and γ-glycidoxypropyltrimethoxysilane to the phosphorus-modified epoxy resin. The mass ratio of the phosphorus-modified epoxy resin to γ-glycidoxypropyltrimethoxysilane is 10:(0.5~1.0). The reaction is carried out under vacuum to obtain an active compatibilizer. (3) Cool and pulverize the active compatibilizer and mix it with fumed silica. The amount of fumed silica added is 1 to 3 wt% of the active compatibilizer product to obtain active compatibilizer powder. (4) Disperse aluminum nitride powder in anhydrous isopropanol, add silane coupling agent KH-550 for surface treatment, the mass ratio of aluminum nitride powder to silane coupling agent KH-550 is 20:(1~3), then add tetraethyl orthosilicate and ammonia water dropwise to the system to carry out silica coating reaction, the mass ratio of aluminum nitride powder to tetraethyl orthosilicate is 20:(6~10), and obtain the coated filler; (5) The coated filler was calcined under a nitrogen atmosphere, then dispersed in anhydrous toluene, and a titanate coupling agent was added for reflux reaction to obtain a surface-modified composite filler. (6) Aminated hyperbranched polysiloxane and nano-hexagonal boron nitride were added to anhydrous toluene, with the mass ratio of aminated hyperbranched polysiloxane to nano-hexagonal boron nitride being 3:(1-2). The mixture was ultrasonically dispersed to obtain a modified liquid. (7) The surface-modified composite filler was added to the modified liquid and refluxed. Then the solvent was removed and the mixture was dried to obtain the reinforced composite filler. (8) The polyetherimide, active compatibilizer powder, reinforcing composite filler and antioxidant are dry mixed at high speed, and then melt extrusion granulation and heat treatment are carried out to obtain the product.

2. The method for preparing a high-temperature resistant insulating material for new energy batteries according to claim 1, characterized in that, In step (8), the mass ratio of polyetherimide to active compatibilizer powder is 100:(5-8).

3. The method for preparing a high-temperature resistant insulating material for new energy batteries according to claim 1, characterized in that, In step (8), the mass ratio of polyetherimide to reinforced composite filler is 100:(35-40).

4. A high-temperature resistant insulating material for new energy batteries, characterized in that, It is prepared by the method described in any one of claims 1 to 3 above.

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