Fluorine-containing polyimide composite thermal insulation foam for lithium battery and preparation method of fluorine-containing polyimide composite thermal insulation foam

Abstract

The invention relates to the technical field of fluorine-containing polyimide composite heat-insulating foam, in particular to fluorine-containing polyimide composite heat-insulating foam for a lithium battery and a preparation method of the fluorine-containing polyimide composite heat-insulating foam. The fluorine-containing polyimide composite thermal insulation foam for the lithium battery comprises the following substances in parts by weight: 10-60 parts of isocyanate, 10-60 parts of fluorine-containing monomers, 10-40 parts of a solvent, 1-10 parts of a foaming agent, 1-10 parts of a flame retardant, 2-15 parts of a foam stabilizer, 0.1-3 parts of a catalyst and 3-10 parts of expandable particles. The fluorine-containing polyimide foam disclosed by the invention has low hardness and high resilience, the buffer effect of a battery main body can be effectively improved, and expandable components in the fluorine-containing polyimide foam can be heated to expand to play a role in buffering and heat insulation, so that heat diffusion is inhibited, and accidents are delayed; when the battery is on fire, the flame-retardant effect of the buffer heat insulation sheet can delay fire spreading, and meanwhile, the buffer heat insulation sheet expands when heated, so that a fire source is effectively isolated, battery damage is prevented from being further expanded, and the maintenance cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of fluorinated polyimide composite thermal insulation foam, in particular to a fluorinated polyimide composite thermal insulation foam for lithium batteries and a preparation method thereof. Background Art

[0002] The energy density and power density of lithium batteries can meet the use requirements of new energy vehicles. However, when using new energy vehicle lithium batteries, they will vibrate with the bumps of the vehicle, causing external damage such as shell cracks and sealing glue cracks, or electrolyte leakage, plate sulfidation, etc., which will damage the internal structure of the battery and reduce its service life. At the same time, lithium batteries will generate a lot of heat when running, which will cause thermal runaway in severe cases. The negative electrode SEI film in the battery cell will decompose, and then the diaphragm will decompose and melt, causing the negative electrode to react with the electrolyte, followed by the decomposition of the positive electrode and the electrolyte, thus causing a large-scale internal short circuit, causing the electrolyte to burn, and then spread to other cells, causing the entire battery pack to spontaneously combust, or even explode, and then quickly cause the new energy vehicle to spontaneously combust, resulting in the tragedy of the car being destroyed and people being killed.

[0003] Therefore, how to set up a material that can reduce the risk of lithium-ion battery spontaneous combustion or increase the reaction time of people on board after the battery pack spontaneously combusts has become one of the focuses of attention of many R&D companies in the industry. By setting up a battery pack buffer insulation sheet, it can play a heat insulation role when the battery has thermal runaway, inhibit heat diffusion, and delay the occurrence of accidents; when the battery catches fire, it can delay the spread of the fire, and can also effectively isolate the fire source and increase the escape time; at the same time, the preparation method is simple, which is conducive to application and promotion in the high-speed train manufacturing industry.

[0004] In view of the above-mentioned related technologies, the inventors found that the performance of the existing battery pack buffer and thermal insulation sheet materials is poor and cannot take into account both good buffering performance and thermal insulation performance. Summary of the invention

[0005] In order to improve the poor performance of existing battery pack buffer insulation sheet materials and the defect that good buffering performance and thermal insulation performance cannot be taken into account, the present application provides a fluorinated polyimide composite insulation foam for lithium batteries and a preparation method thereof.

[0006] In the first aspect, the present application provides a fluorinated polyimide composite thermal insulation foam for lithium batteries, which adopts the following technical solution: A fluorinated polyimide composite thermal insulation foam for lithium batteries comprises the following substances in parts by weight: 10-60 parts of isocyanate, 10-60 parts of fluorinated monomer, 10-40 parts of solvent, 1-10 parts of foaming agent, 1-10 parts of flame retardant, 2-15 parts of foam leveling agent, 0.1-3 parts of catalyst, and 3-10 parts of expandable particles.

[0007] Through the above technical solution, this application optimizes the fluorinated polyimide composite insulation foam through the combination of multiple components, using isocyanate as the main component to provide good adhesion and mechanical strength for the fluorinated polyimide composite insulation foam, while the addition of fluorinated monomers makes the foam have excellent high temperature resistance and corrosion resistance. By mixing the various components in a specific proportion, the thermal stability and flame retardant properties of the foam can be maximized, thereby meeting the use requirements of lithium batteries in high temperature environments.

[0008] Furthermore, the isocyanate includes one or more of polyphenyl polymethylene polyisocyanate, 4,4'-diphenylmethane diisocyanate, 2,6-toluene diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate.

[0009] Through the above technical scheme, the present application optimizes the types of isocyanates. Different isocyanates, such as polyphenyl polymethylene polyisocyanate and hexamethylene diisocyanate, can provide different physical properties and chemical properties in different applications. This diversity not only improves the comprehensive performance of the foam, but also enables the product to adapt to different market demands and technical standards.

[0010] Further, the fluorine-containing monomer includes one or more of hexafluorodianhydride, 4,4'-oxybis[3-(trifluoromethyl)aniline], 4,4'-oxybis[3-(oxytrifluoromethyl)aniline], 4,4'-oxybis[3-fluoroaniline], 2-(trifluoromethyl)-1,4-p-phenylenediamine, 2-(oxytrifluoromethyl)-1,4-p-phenylenediamine, 2-fluoro-1,4-p-phenylenediamine, 2,2'-bis(trifluoromethyl)diaminobiphenyl, 2,2'-bis(oxytrifluoromethyl)diaminobiphenyl and 2,2'-bis(fluoro)diaminobiphenyl.

[0011] Through the above technical solution, the present application enhances the chemical stability and thermal stability of the foam by using fluorinated monomers. By selecting fluorinated compounds such as hexafluorodianhydride, the present application can significantly improve the heat resistance and flame retardancy of the material, and prevent lithium batteries from being dangerous under high temperature or short circuit conditions. In addition, the introduction of these fluorinated monomers enables the foam to maintain excellent physical properties in extreme environments, further ensuring the safety and reliability of lithium batteries.

[0012] Furthermore, the solvent includes one or more of N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methyl-2-pyrrolidone and dimethyl sulfoxide.

[0013] Through the above technical scheme, the present application optimizes the types of solvents. By adjusting the selection of solvents, it not only affects the fluidity and processing performance of the mixture, but also has an important impact on the final properties of the foam. Among them, solvents such as N,N'-dimethylformamide play an important role in improving the solubility of the material and preventing phase separation. Therefore, during the preparation process, through uniform dispersion, each component can fully react, thereby improving the overall performance and consistency of the fluorinated polyimide composite insulation foam for lithium batteries.

[0014] Further, the flame retardant includes one or more of diethylene glycol bis(2-chloroethyl) phosphate, tris(polyoxyalkylene) phosphate, tris(polyoxyalkylene) phosphite, tris(2-chloroethyl) phosphate and diethyl ethyl phosphate.

[0015] Through the above technical solution, the present application can effectively improve the safety of the foam by introducing flame retardants. By using suitable flame retardants, the spread of fire can be delayed, and at the same time, the middle expansion layer expands due to heat, effectively isolating the fire source and increasing the escape time. This improved safety not only protects the product itself, but also provides greater safety protection for users, which meets the high safety standards of modern battery technology.

[0016] Further, the expandable particles include one or more of expandable graphite, expandable perlite powder, expandable vermiculite, expandable microspheres F230D, F190D, EHM401, and EM304.

[0017] Further, the catalyst includes one or more of triethylenediamine, N-methylmorpholine, N,N'-diethylpiperazine, N,N'-diethyl-2-methylpiperazine, N-2-hydroxypropyldimethylmorpholine, triethanolamine, N,N-dimethylethanolamine, stannous octoate, dibutyltin dilaurate, dibutyltin diacetate, potassium isooctanoate, potassium oleate, and cobalt isooctanoate.

[0018] Through the above technical solution, the present application can effectively accelerate the curing process of the foam and improve production efficiency by using catalysts such as triethylenediamine. At the same time, these catalysts can improve the mechanical properties and thermal stability of the final product during the reaction process, ensure the stability of the foam under high temperature conditions, and further broaden its application field.

[0019] In the second aspect, the present application provides a method for preparing a fluorinated polyimide composite thermal insulation foam for a lithium battery, using the following technical scheme: A method for preparing a fluorinated polyimide composite thermal insulation foam for a lithium battery comprises the following preparation steps: First, a fluorine-containing monomer is placed in a solvent, heated, and a foaming agent, a flame retardant, a foam leveling agent, a catalyst and expandable microspheres are added, and the mixture is kept warm for reaction to prepare a foaming mixed liquid; The foaming mixed liquid and isocyanate are mixed and placed in a mold, freely foamed and molded, and pre-cured and post-cured to prepare the fluorinated polyimide composite thermal insulation foam material for the battery.

[0020] Through the above technical scheme, the present application pre-treats the fluorine-containing monomer to ensure the uniformity and sufficiency of the reaction, thereby improving the stability and consistency of the foam and enhancing the performance of the final product. The present application uses free foaming molding technology to help form a more uniform and continuous foam structure, thereby improving the thermal insulation performance, mechanical strength and resilience of the material.

[0021] Furthermore, the heat preservation reaction is carried out at 60-90° C. for 2-6 hours.

[0022] Furthermore, the pre-curing treatment is a microwave pre-curing treatment, in which the microwave power is set to 1000-8000W in a phased gradient, and the post-curing treatment is a curing treatment at 200-250°C for 2-8h.

[0023] Through the above technical solution, the present application greatly improves the strength and stability of the foam by introducing microwave pre-curing treatment and combining it with subsequent high-temperature curing treatment. The staged gradient setting of microwaves can effectively control the curing process and ensure the uniformity and consistency of the internal structure of the foam. At the same time, high-temperature curing further enhances the heat resistance and overall performance of the foam.

[0024] In summary, this application has the following beneficial effects: First, this application optimizes the fluorinated polyimide composite insulation foam through the combination of multiple components, using isocyanate as the main component to provide good adhesion and mechanical strength for the fluorinated polyimide composite insulation foam, while the addition of fluorinated monomers gives the foam excellent high temperature resistance and corrosion resistance. By mixing the components in a specific proportion, the thermal stability and flame retardant properties of the foam can be maximized, thereby meeting the use requirements of lithium batteries in high temperature environments.

[0025] Second, the present application optimizes the types of isocyanates. Different isocyanates, such as polyphenyl polymethylene polyisocyanate and hexamethylene diisocyanate, can provide different physical properties and chemical properties in different applications. This diversity not only improves the comprehensive performance of the foam, but also enables the product to adapt to different market demands and technical standards.

[0026] Third, the present application enhances the chemical stability and thermal stability of the foam by using fluorinated monomers. By selecting fluorinated compounds such as hexafluorodianhydride, the present application can significantly improve the heat resistance and flame retardancy of the material, and prevent lithium batteries from being dangerous under high temperature or short circuit conditions. In addition, the introduction of these fluorinated monomers enables the foam to maintain excellent physical properties under extreme conditions, further ensuring the safety and reliability of lithium batteries. DETAILED DESCRIPTION

[0027] The present application is further described in detail below with reference to the embodiments.

[0028] In the examples of the present application, the raw materials and instruments used are as follows, but not limited thereto. Raw materials not otherwise specified are of analytical grade.

[0029] Example 1 A method for preparing a fluorinated polyimide composite thermal insulation foam for a lithium battery comprises the following preparation steps: 25 kg of hexafluorodianhydride and 24 kg of 4,4'-oxybis[3-(oxytrifluoromethyl)aniline] were stirred in 40 kg of N,N'-dimethylformamide and heated to 65°C for reaction for 3 hours, and then allowed to stand and cool to room temperature to obtain a reaction solution; 5 kg of n-pentane, 6 kg of tri(polyoxyalkylene) phosphate, 5 kg of L550, 1 kg of dibutyltin diacetate, and 5 kg of expandable graphite were added to the reaction solution and stirred for 2 hours to prepare a foamable mixed solution; Add 40 kg of polyphenyl polymethylene polyisocyanate into the foamable mixed liquid, stir at a stirring speed of 3000 r / min for 20 seconds, then introduce it into a mold for free foaming for 1 hour, place the foamed body in a microwave heating device, heat it at a microwave power of 3 kW for 1 hour, and then put it in an oven at 230°C for 5 hours to obtain a fluorinated polyimide composite insulating foam.

[0030] Example 2 A method for preparing a fluorinated polyimide composite thermal insulation foam for a lithium battery comprises the following preparation steps: 25 kg of hexafluorodianhydride and 60 kg of 2-(oxytrifluoromethyl)-1,4-p-phenylenediamine were stirred in 30 kg of N,N'-dimethylacetamide and heated to 65°C for reaction for 3 hours, and then allowed to stand and cool to room temperature to obtain a reaction solution; 6 kg of ethanol, 5 kg of diethylene glycol bis(2-chloroethyl) phosphate, 5 kg of L580, 2 kg of triethylenediamine, and 8 kg of expandable perlite powder were added to the reaction solution and stirred for 3 hours to prepare a foamable mixed solution; Add 30kg 4,4'-diphenylmethane diisocyanate into the foamable mixed liquid, stir at a stirring speed of 4000r / min for 25s, then introduce it into a mold for free foaming for 50min, place the foamed body in a microwave heating device, heat it at a microwave power of 4kW for 50min, and then put it in an oven at 240℃ for 4h to obtain the fluorinated polyimide composite insulating foam.

[0031] Example 3 A method for preparing a fluorinated polyimide composite thermal insulation foam for a lithium battery comprises the following preparation steps: 28 kg of hexafluorodianhydride and 15 kg of 2,2'-bis(trifluoromethyl)diaminobiphenyl were stirred in 30 kg of N,N'-dimethylacetamide and heated to 85°C for reaction for 3 hours, and then allowed to stand and cool to room temperature to obtain a reaction solution; 3 kg of ethanol, 5 kg of diethylene glycol bis(2-chloroethyl) phosphate, 5 kg of OFX-8468, 2 kg of triethylenediamine, and 10 kg of expandable vermiculite were added to the reaction solution and stirred for 4 hours to prepare a foamable mixed solution; 35 kg of polyphenyl polymethylene polyisocyanate is added to the foamable mixed liquid, and after stirring at a stirring speed of 4000 r / min for 25 seconds, the mixture is introduced into a mold for free foaming for 50 minutes. The foamed body is placed in a microwave heating device, heated at a microwave power of 5 kW for 50 minutes, and then placed in an oven at 240°C for 4 hours to obtain a fluorinated polyimide composite insulating foam.

[0032] It should be noted that in this application: Isocyanates include, but are not limited to, one or more of polyphenyl polymethylene polyisocyanate, 4,4'-diphenylmethane diisocyanate, 2,6-toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate; The solvent includes, but is not limited to, one or more of N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methyl-2-pyrrolidone and dimethyl sulfoxide; The blowing agent includes, but is not limited to, one or more of water, methanol, ethanol, ethylene glycol monobutyl ether, n-pentane and acetone; The flame retardant includes, but is not limited to, one or more of diethylene glycol bis(2-chloroethyl) phosphate, tris(polyoxyalkylene) phosphate, tris(polyoxyalkylene) phosphite, tris(2-chloroethyl) phosphate, and diethyl ethyl phosphate; The foam leveling agent includes, but is not limited to, one or more of OFX-0193, OFX-8417, OFX-8468, L550, L540, L580, L668, and L5333.

[0033] The catalyst includes, but is not limited to, one or more of triethylenediamine, N-methylmorpholine, N,N'-diethylpiperazine, N,N'-diethyl-2-methylpiperazine, N-2-hydroxypropyldimethylmorpholine, triethanolamine, N,N-dimethylethanolamine, stannous octoate, dibutyltin dilaurate, dibutyltin diacetate, potassium isooctanoate, potassium oleate, and cobalt isooctanoate.

[0034] The expandable microparticles include, but are not limited to, one or more of expandable graphite, expandable perlite powder, expandable vermiculite, expandable microspheres F230D, F190D, EHM401, and EM304.

[0035] Comparative Example In a three-necked flask equipped with a mechanical stirrer, a thermometer, and a reflux condenser, 36.6 g (0.1 mol) of 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane dissolved in N,N'-dimethylformamide (DMF), 42.7 g (0.1 mol) of 1,4-difluoropyromellitic dianhydride, and 1.6 g (0.01 mol) of a capping agent 5-norbornene-2,3-dicarboxylic anhydride were added in order according to the ratio. The cooling liquid was circulated under stirring to maintain the reaction at 10°C for condensation reaction. The total condensation reaction took about 6.5 hours. ; The system was heated to 20°C, and an organic base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was added to neutralize the system to a pH value of 6.5; the resin system was dehydrated under reduced pressure at a vacuum degree of 0.081 MPa and a temperature of 60°C in a water bath until the viscosity reached 5800 mPa.s, and the dehydration was stopped. The system was cooled to 50°C and discharged to obtain a fluorinated polyimide C. 100 parts by weight of the fluorinated polyimide C was rapidly foamed under a microwave condition of 700 W for 10 minutes, and the system was placed at room temperature for 2 hours for post-curing to prepare a fluorinated polyimide foam.

[0036] Performance Testing The performance of the fluorinated polyimide composite thermal insulation foam for lithium batteries prepared in Examples 1-3 and the fluorinated polyimide foam prepared in the comparative example was tested: Performance test standard: according to DB51 / T 2683-2020 standard; The results are shown in Table 1 below: Table 1 Performance test table

[0037] From the above examples 1-3 and the comparative example, combined with the test results in Table 1, it can be found that: From the comparison of Examples 1-3 and the comparative example, it is shown that the technical solution of the present application optimizes the fluorinated polyimide composite thermal insulation foam through the combination of multiple components, and uses isocyanate as the main component to provide good adhesion and mechanical strength for the fluorinated polyimide composite thermal insulation foam. At the same time, the addition of fluorinated monomers makes the foam have excellent high temperature resistance and corrosion resistance. By mixing the components in a specific proportion, the thermal stability and flame retardant properties of the foam can be maximized, thereby meeting the use requirements of lithium batteries in high temperature environments.

[0038] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

[0039] All publications, patent applications, patents and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings conventionally understood by those skilled in the art. In the event of a conflict, the definition in this specification shall prevail.

[0040] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0041] In the context of the present specification, any matters or items not mentioned are directly applicable to those known in the art without any changes except those explicitly stated.

Claims

1. A fluorinated polyimide composite thermal insulation foam for lithium batteries, characterized in that: The composition includes the following materials in parts by weight: Isocyanate 10-60 parts; 10-60 parts of fluorine-containing monomer; 10-40 parts of solvent; 1-10 parts of foaming agent; Flame retardant 1-10 parts; 2-15 parts of foam leveling agent; Catalyst 0.1-3 parts; 3-10 parts of expandable microparticles.

2. The fluorinated polyimide composite thermal insulation foam for lithium battery according to claim 1, characterized in that: The isocyanate includes one or more of polyphenyl polymethylene polyisocyanate, 4,4'-diphenylmethane diisocyanate, 2,6-toluene diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate.

3. The fluorinated polyimide composite thermal insulation foam for lithium battery according to claim 1, characterized in that: The fluorine-containing monomer includes one or more of hexafluorodianhydride, 4,4'-oxybis[3-(trifluoromethyl)aniline], 4,4'-oxybis[3-(oxytrifluoromethyl)aniline], 4,4'-oxybis[3-fluoroaniline], 2-(trifluoromethyl)-1,4-p-phenylenediamine, 2-(oxytrifluoromethyl)-1,4-p-phenylenediamine, 2-fluoro-1,4-p-phenylenediamine, 2,2'-bis(trifluoromethyl)diaminobiphenyl, 2,2'-bis(oxytrifluoromethyl)diaminobiphenyl and 2,2'-bis(fluoro)diaminobiphenyl.

4. The fluorinated polyimide composite thermal insulation foam for lithium battery according to claim 1, characterized in that: The solvent includes one or more of N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methyl-2-pyrrolidone and dimethyl sulfoxide.

5. The fluorinated polyimide composite thermal insulation foam for lithium battery according to claim 1, characterized in that: The flame retardant includes one or more of diethylene glycol bis(2-chloroethyl) phosphate, tris(polyoxyalkylene) phosphate, tris(polyoxyalkylene) phosphite, tris(2-chloroethyl) phosphate and diethyl ethyl phosphate.

6. The fluorinated polyimide composite thermal insulation foam for lithium battery according to claim 1, characterized in that: The expandable particles include one or more of expandable graphite, expandable perlite powder, expandable vermiculite, expandable microspheres F230D, F190D, EHM401, and EM304.

7. The fluorinated polyimide composite thermal insulation foam for lithium battery according to claim 1, characterized in that: The catalyst includes one or more of triethylenediamine, N-methylmorpholine, N,N'-diethylpiperazine, N,N'-diethyl-2-methylpiperazine, N-2-hydroxypropyldimethylmorpholine, triethanolamine, N,N-dimethylethanolamine, stannous octoate, dibutyltin dilaurate, dibutyltin diacetate, potassium isooctanoate, potassium oleate, and cobalt isooctanoate.

8. The method for preparing a fluorinated polyimide composite thermal insulation foam for lithium battery according to any one of claims 1 to 7, characterized in that: The method comprises the following preparation steps: First, a fluorine-containing monomer is placed in a solvent, heated, and a foaming agent, a flame retardant, a foam leveling agent, a catalyst and expandable microspheres are added, and the mixture is kept warm for reaction to prepare a foaming mixed liquid; The foaming mixed liquid and isocyanate are mixed and placed in a mold, freely foamed and molded, and pre-cured and post-cured to prepare the fluorinated polyimide composite thermal insulation foam material for the battery.

9. The method for preparing a fluorinated polyimide composite thermal insulation foam for lithium batteries according to claim 8, characterized in that: The heat preservation reaction is carried out at 60-90° C. for 2-6 hours.

10. The method for preparing a fluorinated polyimide composite thermal insulation foam for lithium batteries according to claim 8, characterized in that: The pre-curing treatment is a microwave pre-curing treatment, in which the microwave power is set to 1000-8000W in a phased gradient, and the post-curing treatment is a curing treatment at 200-250°C for 2-8h.

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