Highly resistant battery electrolyte fluororubber sealing material and its preparation method

Abstract

The application belongs to the technical field of battery materials, and particularly relates to a high-battery-electrolyte-resistant fluororubber sealing material and a preparation method thereof. The high-battery-electrolyte-resistant fluororubber sealing material comprises the following components in mass fraction: 100 parts of fluororubber, 20-25 parts of white carbon black, 5-10 parts of calcium fluoride, 5-10 parts of modified carbon nanotubes, 4-8 parts of acid absorbent, 2-3 parts of vulcanizing agent, 1-1.5 parts of accelerator, and 0.5-1.5 parts of processing aid. The fluororubber sealing material prepared by the application has high mechanical strength, excellent high-temperature aging resistance and excellent lithium iron phosphate battery electrolyte resistance, and can meet the stringent requirements of new-generation high-safety and long-life power batteries on sealing materials.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, specifically relating to a high-resistance fluororubber sealing material for battery electrolytes and its preparation method. Background Technology

[0002] With the rapid development of the new energy vehicle industry, lithium-ion batteries, as a core power source, are receiving increasing attention for their safety, reliability, and lifespan. Among them, lithium iron phosphate (LiFePO4) batteries are widely used in electric vehicles, energy storage systems, and other fields due to their high thermal stability, long cycle life, and good safety. In the battery structure, sealing materials are key components that ensure the stability of the internal electrochemical system and prevent electrolyte leakage and external moisture intrusion; their performance directly affects the overall reliability and service life of the battery.

[0003] Currently, commercial lithium-ion batteries generally use organic liquid electrolytes, mainly composed of lithium salts (such as LiPF6), carbonate solvents (such as EC, DMC, EMC, etc.), and functional additives. These electrolytes are highly polar, somewhat corrosive, and easily decompose at high temperatures to produce acidic substances such as HF, imposing stringent requirements on the chemical stability of sealing materials. Fluororubber (FKM) is considered an ideal candidate for lithium-ion battery sealing materials due to its excellent high-temperature resistance, oil resistance, and chemical inertness. However, existing commercially available fluororubber materials still have significant shortcomings in practical applications: on the one hand, after prolonged immersion in lithium iron phosphate battery electrolytes at high temperatures, the volume swelling rate is high, and the mechanical properties decrease significantly; on the other hand, under high-temperature aging conditions, the tensile strength retention rate of the material is low, making it difficult to meet the requirements of long-term high-temperature storage or use under extreme operating conditions.

[0004] Invention patent CN114672116B discloses a low-compression-stress-relaxation fluororubber for battery seals and its preparation method. Seals made from this fluororubber have advantages such as high temperature resistance, electrolyte resistance, acid and alkali resistance, chemical corrosion resistance, good sealing reliability, and long service life. However, the aging resistance of existing fluororubber materials is not ideal at temperatures above 200°C.

[0005] Therefore, there is an urgent need to develop a fluororubber sealing material that combines high mechanical strength, excellent high-temperature aging resistance, and superior resistance to lithium iron phosphate battery electrolytes to meet the stringent requirements of the next generation of high-safety, long-life power batteries for sealing materials. Summary of the Invention

[0006] The purpose of this invention is to provide a fluororubber sealing material with high resistance to battery electrolyte and its preparation method.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A high-resistance fluororubber sealing material for battery electrolytes comprises the following components in parts by weight: 100 parts fluororubber, 20-25 parts silica, 5-10 parts calcium fluoride, 5-10 parts modified carbon nanotubes, 4-8 parts acid absorber, 2-3 parts vulcanizing agent, 1-1.5 parts accelerator, and 0.5-1.5 parts processing aid.

[0009] Preferably, the modified carbon nanotubes are prepared by coating the surface of hydroxylated carbon nanotubes with a fluorinated copolymer composed of methyl methacrylate and tridecafluorooctyl acrylate.

[0010] Preferably, the method for preparing the modified carbon nanotubes includes the following steps:

[0011] (1) Pretreated carbon nanotubes are obtained by reacting silane coupling agent with hydroxylated carbon nanotubes;

[0012] (2) Mix the pretreated carbon nanotubes, deionized water and emulsifier, heat and stir to obtain a pre-emulsion;

[0013] (3) Under a nitrogen atmosphere, an initiator, methyl methacrylate and tridecyl fluorooctyl acrylate were added to the pre-emulsion, heated to react, cooled, demulsified, centrifuged, washed, vacuum dried and ground to obtain modified carbon nanotubes.

[0014] Carbon nanotubes possess excellent heat resistance and weather resistance, but due to their small average particle size, they have poor compatibility with fluororubber. The modified carbon nanotubes of this invention can improve dispersion performance in fluororubber systems, effectively resist swelling and penetration by polar electrolytes, and enhance aging resistance.

[0015] Preferably, the fluororubber includes fluororubber A, fluororubber B, and fluororubber C; fluororubber A is copolymerized from vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene, and has a Mooney viscosity of 15-80 MU at 121°C; fluororubber B is a copolymer of vinylidene fluoride and hexafluoropropylene, and has a Mooney viscosity of 20-35 MU at 121°C; fluororubber C is a bisphenol-cured copolymer, and has a Mooney viscosity of 21-23 MU at 121°C.

[0016] Preferably, the fluororubber comprises fluororubber A, fluororubber B and fluororubber C in a mass ratio of (1.2-1.4):(0.4-0.6):(0.8-1.0).

[0017] This invention utilizes three fluororubber raw materials with specific ratios and compositions to improve the mechanical properties and electrolyte resistance of the product. Analysis shows that under these conditions, the synergistic effect of the ternary combination can be achieved, resulting in an optimal phase structure, high uniformity of the crosslinking network, high crosslinking density and thermal stability of the entire system, and resistance to network damage under high-temperature aging in electrolytes.

[0018] Preferably, the acid absorbent is magnesium oxide.

[0019] Preferably, the accelerator is benzyltriphenylphosphine chloride.

[0020] Preferably, the vulcanizing agent is bisphenol AF.

[0021] Preferably, the processing aid is polyethylene wax.

[0022] The preparation method of the high battery electrolyte fluororubber sealing material includes the following steps: fluororubber is put into a mixer for plasticizing, silica, calcium fluoride, modified carbon nanotubes, acid absorber and some processing aids are added in sequence for primary mixing, the remaining components are added for secondary mixing, and then vulcanization is performed to obtain the high battery electrolyte fluororubber sealing material.

[0023] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0024] 1. This invention uses three fluororubber raw materials with specific ratios and compositions, which can improve the mechanical properties and electrolyte resistance of the product. Under these conditions, the synergistic effect of the ternary combination can be achieved, the optimal phase structure can be reached, the crosslinking network has high uniformity, the crosslinking density and thermal stability of the entire system are high, and the network is not easily destroyed under high-temperature aging in electrolyte.

[0025] 2. The modified carbon nanotubes of the present invention can improve the dispersion performance in fluororubber systems, effectively resist the swelling and penetration of polar electrolytes, and improve aging resistance. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only 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.

[0027] All raw materials used in the following embodiments of the present invention are commercially available products:

[0028] Acid absorbent: magnesium oxide.

[0029] Accelerator: Benzyltriphenylphosphine chloride, CAS: 1100-88-5, Nanjing Chemical Reagent Co., Ltd.

[0030] Vulcanizing agent: Bisphenol AF, CAS: 1478-61-1, Wuhan Smike Biotechnology Co., Ltd.

[0031] Processing aid: Polyethylene wax, model: Honeywell A-C8, Cansen Chemical New Materials (Shenzhen) Co., Ltd.

[0032] Hydroxylated carbon nanotubes, item number 100226, Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0033] Silica: Fumed silica A200, Jinan Zhongbei Fine Chemical Co., Ltd.

[0034] TritonX-100: CAS: 9002-93-1, Jining Tangyi Chemical Co., Ltd.

[0035] Example 1

[0036] This embodiment provides a high-resistance fluororubber sealing material for battery electrolytes, comprising the following components in parts by weight: 100 parts fluororubber, 22 parts silica, 8 parts calcium fluoride, 6 parts modified carbon nanotubes, 5 parts acid absorber, 2.4 parts vulcanizing agent, 1.2 parts accelerator, and 1.0 part processing aid.

[0037] The fluororubber includes fluororubber A, fluororubber B, and fluororubber C in a mass ratio of 1.3:0.5:1.0.

[0038] Fluororubber A is copolymerized from vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene. Its Mooney viscosity at 121℃ is 15-80 MU. Unit: ML (1+10) 121℃; Shandong Huaxia Shenzhou New Material Co., Ltd., Fluororubber raw rubber (ternary rubber grade), model: 246.

[0039] Fluororubber B is a copolymer of vinylidene fluoride and hexafluoropropylene, with a Mooney viscosity of 20-35 MU at 121°C. Produced by Shandong Huaxia Shenzhou New Materials Co., Ltd., fluororubber raw rubber (binary rubber grade), model 268.

[0040] Fluororubber C is a binary bisphenol-cured copolymer with a Mooney viscosity of 23 MU at 121°C. It is manufactured by Daikin Industries, Japan, and its model number is DAI-ELG-310LBP.

[0041] The preparation method of the modified carbon nanotubes includes the following steps: by mass parts,

[0042] (1) Mix 120 parts of anhydrous ethanol, 8 parts of deionized water, 4 parts of ammonia water with a mass concentration of 27% and 2.5 parts of γ-methacryloyloxypropyltrimethoxysilane (CAS: 2530-85-0, Nanjing Pinning Coupling Agent Co., Ltd.) evenly, add 6 parts of hydroxylated carbon nanotubes, stir and disperse at 300 rpm for 30 min, heat to 75℃, and react at a constant temperature for 6 h; after the reaction is completed, centrifuge to separate, wash the solid with anhydrous ethanol 4 times, vacuum dry at 75℃ for 10 h, grind until the powder passes through a 325 mesh sieve to obtain pretreated carbon nanotubes;

[0043] (2) Mix 0.25 parts of pretreated carbon nanotubes, 120 parts of deionized water, 0.5 parts of Triton X-100 and 0.25 parts of sodium dodecylbenzenesulfonate, stir at 500 rpm for 30 min at room temperature, and heat the system to 55°C under nitrogen protection, keep it at the temperature and stir at 300 rpm for 25 min to obtain a pre-emulsion.

[0044] (3) Under a nitrogen atmosphere, add 0.06 parts of potassium persulfate to the pre-emulsion, heat to 78°C, react for 40 min, maintain 78°C, and add 5.5 parts of pre-mixed methyl methacrylate and 5.5 parts of tridecyl fluorooctyl acrylate and 0.09 parts of potassium persulfate solution dissolved in 10 parts of water at a uniform rate through two independent dropping funnels. The uniform dropping time is 4 h, the temperature is raised to 85°C, and the temperature is maintained for 1.5 h. After cooling to room temperature, under continuous stirring, add the same volume of saturated sodium chloride aqueous solution to break the emulsion, let stand for 10 min, centrifuge, wash the solid twice with deionized water, vacuum dry, and grind until the powder passes through a 325 mesh sieve to obtain modified carbon nanotubes.

[0045] The preparation method of the high-resistance battery electrolyte fluororubber sealing material includes the following steps: fluororubber is put into a mixer, preheated to 60°C, and plasticized for 2 minutes. Then, silica, calcium fluoride, modified carbon nanotubes, acid absorber, and 2 / 3 of the processing aids are added sequentially for primary mixing. When the temperature reaches 105°C, the mixer is opened to discharge the rubber, resulting in a primary mixed rubber compound. After standing for 24 hours, the primary mixed rubber compound is put back into the mixer, and vulcanizing agent, accelerator, and the remaining processing aids are added for secondary mixing at 85°C for 5 minutes, resulting in a secondary mixed rubber compound. The secondary mixed rubber compound is then vulcanized. The first vulcanization is carried out at a pressure of 12 MPa, a temperature of 170°C, and a vulcanization time of 15 minutes. The second vulcanization conditions are: room temperature rises to 120°C and is held for 1 hour, then rises to 180°C and is held for 1 hour, then rises to 250°C and is held for 3.5 hours, resulting in the high-resistance battery electrolyte fluororubber sealing material.

[0046] Example 2

[0047] This embodiment provides a high-resistance fluororubber sealing material for battery electrolytes, comprising the following components in parts by weight: 100 parts fluororubber, 25 parts silica, 5 parts calcium fluoride, 10 parts modified carbon nanotubes, 4 parts acid absorber, 3 parts vulcanizing agent, 1 part accelerator, and 1.5 parts processing aid.

[0048] The fluororubber comprises fluororubber A, fluororubber B, and fluororubber C in a mass ratio of 1.2:0.6:0.8. Fluororubber A is copolymerized from vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene, with a Mooney viscosity of 15-80 MU at 121°C (unit: ML (1+10) 121°C). Shandong Huaxia Shenzhou New Materials Co., Ltd. Fluororubber raw rubber (ternary rubber grade), model: 246. Fluororubber B is a copolymer of vinylidene fluoride and hexafluoropropylene, with a Mooney viscosity of 20-35 MU at 121°C. Shandong Huaxia Shenzhou New Materials Co., Ltd. Fluororubber raw rubber (binary rubber grade), model: 268. Fluororubber C is a binary bisphenol cured copolymer, with a Mooney viscosity of 23 MU at 121°C. Daikin Industries, Japan, model: DAI-ELG-310LBP.

[0049] The preparation method of modified carbon nanotubes includes the following steps: by mass parts,

[0050] (1) Mix 120 parts of anhydrous ethanol, 8 parts of deionized water, 4 parts of ammonia water with a mass concentration of 27% and 2.5 parts of γ-methacryloyloxypropyltrimethoxysilane (CAS: 2530-85-0, Nanjing Pinning Coupling Agent Co., Ltd.) evenly, add 6 parts of hydroxylated carbon nanotubes, stir and disperse at 300 rpm for 30 min, heat to 75℃, and react at a constant temperature for 6 h; after the reaction is completed, centrifuge to separate, wash the solid with anhydrous ethanol 4 times, vacuum dry at 75℃ for 10 h, grind until the powder passes through a 325 mesh sieve to obtain pretreated carbon nanotubes;

[0051] (2) Mix 0.25 parts of pretreated carbon nanotubes, 120 parts of deionized water, 0.5 parts of Triton X-100 and 0.25 parts of sodium dodecylbenzenesulfonate, stir at 500 rpm for 30 min at room temperature, and heat the system to 55°C under nitrogen protection, keep it at the temperature and stir at 300 rpm for 25 min to obtain a pre-emulsion.

[0052] (3) Under a nitrogen atmosphere, add 0.06 parts of potassium persulfate to the pre-emulsion, heat to 78°C, react for 40 min, maintain 78°C, and add 5.5 parts of pre-mixed methyl methacrylate and 5.5 parts of tridecyl fluorooctyl acrylate and 0.09 parts of potassium persulfate solution dissolved in 10 parts of water at a uniform rate through two independent dropping funnels. The uniform dropping time is 4 h, the temperature is raised to 85°C, and the temperature is maintained for 1.5 h. After cooling to room temperature, under continuous stirring, add the same volume of saturated sodium chloride aqueous solution to break the emulsion, let stand for 10 min, centrifuge, wash the solid twice with deionized water, vacuum dry, and grind until the powder passes through a 325 mesh sieve to obtain modified carbon nanotubes.

[0053] The preparation method of the high-resistance battery electrolyte fluororubber sealing material includes the following steps: fluororubber is put into a mixer, preheated to 60°C, and plasticized for 2 minutes. Then, silica, calcium fluoride, modified carbon nanotubes, acid absorber, and 2 / 3 of the processing aids are added sequentially for primary mixing. When the temperature reaches 105°C, the mixer is opened to discharge the rubber, resulting in a primary mixed rubber compound. After standing for 24 hours, the primary mixed rubber compound is put back into the mixer, and vulcanizing agent, accelerator, and the remaining processing aids are added for secondary mixing at 85°C for 5 minutes, resulting in a secondary mixed rubber compound. The secondary mixed rubber compound is then vulcanized. The first vulcanization is carried out at a pressure of 12 MPa, a temperature of 170°C, and a vulcanization time of 15 minutes. The second vulcanization conditions are: room temperature rises to 120°C and is held for 1 hour, then rises to 180°C and is held for 1 hour, then rises to 250°C and is held for 3.5 hours, resulting in the high-resistance battery electrolyte fluororubber sealing material.

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 1 is that the preparation method of the modified carbon nanotubes includes the following steps: by mass fraction, 120 parts of anhydrous ethanol, 8 parts of deionized water, 4 parts of ammonia water with a mass concentration of 27% and 2.5 parts of γ-methacryloyloxypropyltrimethoxysilane (CAS: 2530-85-0, Nanjing Pinning Coupling Agent Co., Ltd.) are mixed evenly, 6 parts of hydroxylated carbon nanotubes are added, the mixture is stirred and dispersed at 300 rpm for 30 min, the temperature is raised to 75℃, and the reaction is kept at a constant temperature for 6 h; after the reaction is completed, the solid is separated by centrifugation, washed 4 times with anhydrous ethanol, vacuum dried at 75℃ for 10 h, and ground until the powder passes through a 325 mesh sieve to obtain modified carbon nanotubes.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 1 is that the fluororubber is copolymerized from vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene, and has a Mooney viscosity of 15-80 MU at 121°C. (Unit: ML (1+10) 121°C). Shandong Huaxia Shenzhou New Materials Co., Ltd. Fluororubber raw rubber (ternary rubber grade), model: 246.

[0058] Comparative Example 3

[0059] The difference between this comparative example and Example 1 is that the fluororubber includes fluororubber A and fluororubber B in a mass ratio of 1.3:0.5. Fluororubber A is copolymerized from vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene, with a Mooney viscosity of 15-80 MU at 121°C (unit: ML (1+10) 121°C). Shandong Huaxia Shenzhou New Materials Co., Ltd. Fluororubber raw rubber (ternary rubber grade), model: 246. Fluororubber B is a copolymer of vinylidene fluoride and hexafluoropropylene, with a Mooney viscosity of 20-35 MU at 121°C. Shandong Huaxia Shenzhou New Materials Co., Ltd. Fluororubber raw rubber (binary rubber grade), model: 268.

[0060] Comparative Example 4

[0061] The difference between this comparative example and Example 1 is that the fluororubber includes fluororubber A, fluororubber B, and fluororubber C in a mass ratio of 1:0.8:0.5. Fluororubber A is copolymerized from vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene, with a Mooney viscosity of 15-80 MU at 121°C (unit: ML (1+10) 121°C). Shandong Huaxia Shenzhou New Materials Co., Ltd. Fluororubber raw rubber (ternary rubber grade), model: 246. Fluororubber B is a copolymer of vinylidene fluoride and hexafluoropropylene, with a Mooney viscosity of 20-35 MU at 121°C. Shandong Huaxia Shenzhou New Materials Co., Ltd. Fluororubber raw rubber (binary rubber grade), model: 268. Fluororubber C is a binary bisphenol cured copolymer, with a Mooney viscosity of 23 MU at 121°C. Daikin Industries, Japan, model: DAI-ELG-310LBP.

[0062] Comparative Example 5

[0063] The difference between this comparative example and Example 1 is that the preparation method of the modified carbon nanotubes includes the following steps: by mass parts,

[0064] (1) Mix 120 parts of anhydrous ethanol, 8 parts of deionized water, 4 parts of ammonia water with a mass concentration of 27% and 2.5 parts of γ-methacryloyloxypropyltrimethoxysilane (CAS: 2530-85-0, Nanjing Pinning Coupling Agent Co., Ltd.) evenly, add 6 parts of hydroxylated carbon nanotubes, stir and disperse at 300 rpm for 30 min, heat to 75℃, and react at a constant temperature for 6 h; after the reaction is completed, centrifuge to separate, wash the solid with anhydrous ethanol 4 times, vacuum dry at 75℃ for 10 h, grind until the powder passes through a 325 mesh sieve to obtain pretreated carbon nanotubes;

[0065] (2) Mix 0.25 parts of pretreated carbon nanotubes, 120 parts of deionized water, 0.5 parts of Triton X-100 and 0.25 parts of sodium dodecylbenzenesulfonate, stir at 500 rpm for 30 min at room temperature, and heat the system to 55°C under nitrogen protection, keep it at the temperature and stir at 300 rpm for 25 min to obtain a pre-emulsion.

[0066] (3) Under a nitrogen atmosphere, add 0.06 parts of potassium persulfate to the pre-emulsion, heat to 78°C, react for 40 min, maintain 78°C, and add 11 parts of methyl methacrylate and 0.09 parts of potassium persulfate solution dissolved in 10 parts of water dropwise at a uniform rate through two independent dropping funnels. The uniform dropping time is 4 h, the temperature is raised to 85°C, and the temperature is maintained for 1.5 h. After cooling to room temperature, under continuous stirring, add the same volume of saturated sodium chloride aqueous solution to break the emulsion, let stand for 10 min, centrifuge, wash the solid twice with deionized water, vacuum dry, and grind until the powder passes through a 325 mesh sieve to obtain modified carbon nanotubes.

[0067] Comparative Example 6

[0068] This comparative example is the product of Example 1 in CN114672116B, "Low Compression Stress Relaxation Fluoror Rubber for Battery Sealing and its Preparation Method Thereof".

[0069] Performance testing

[0070] Performance tests were conducted on the products of Examples 1-2 and Comparative Examples 1-6.

[0071] (1) Mechanical strength: In accordance with GB / T528-2009, tensile strength and elongation at break were tested using a universal testing machine at a tensile speed of 500 mm / min;

[0072] (2) Aging resistance: Refer to GB / T528-2009, temperature 300℃ / 150h, stand at room temperature for 30h, and test the tensile strength of the aged sample. Tensile strength retention rate (%) = tensile strength after aging / tensile strength before aging × 100%.

[0073] (3) Electrolyte resistance: The fluororubber sealing material was completely immersed in the electrolyte (brand: Xinzhoubang; model: lithium iron phosphate battery electrolyte LBC333) at 85℃ for 70h; the volume change rate before and after immersion was calculated as (volume after immersion - volume before immersion) / volume before immersion × 100%.

[0074] The results of the performance tests are shown in Table 1.

[0075] Table 1 Performance Test Results

[0076] Tensile strength MPa Elongation at break % Tensile strength retention rate Volume change rate Example 1 7.5 298 76.1 25.7 Example 2 7.2 286 75.4 26.8 Comparative Example 1 5.9 241 65.6 31.4 Comparative Example 2 6.3 254 68.2 29.6 Comparative Example 3 6.4 276 60.3 32.8 Comparative Example 4 6.1 250 66.7 30.1 Comparative Example 5 6.8 265 62.4 32.0 Comparative Example 6 6.0 213 53.8 32.4

[0077] As shown in Table 1, the fluororubber sealing materials prepared in Examples 1-2 possess high mechanical strength, excellent high-temperature aging resistance, and superior resistance to lithium iron phosphate battery electrolyte.

[0078] Comparative Example 1 shows that using only silane to modify carbon nanotubes reduces the overall performance of fluororubber sealing materials.

[0079] The rubber system in Comparative Example 2 exhibits limited performance, failing to achieve the synergistic effect of ternary components, and suffers from poor crosslinking network uniformity and performance degradation.

[0080] The lack of bisphenol-cured fluororubber C in Comparative Example 3 resulted in insufficient crosslinking density and thermal stability of the entire system. Under high-temperature aging in the electrolyte, the network was more easily damaged, leading to severe performance degradation.

[0081] In Comparative Example 4, the imbalance of rubber proportions disrupted the optimal phase structure, leading to poor compatibility and stress concentration, and the overall performance could not reach its best state.

[0082] In Comparative Example 5, the carbon nanotube coating layer does not contain fluorine, resulting in poor compatibility with fluororubber. It cannot effectively resist the swelling and penetration of polar electrolyte, leading to a severe decline in performance after aging.

[0083] Comparative Example 6 shows that the overall performance of the product in the prior art is inferior to that of the present invention. It should be noted that the present invention uses the same testing standard, which is different from the testing method of patent CN114672116B, so the values ​​are different.

[0084] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A fluororubber sealing material with high resistance to battery electrolyte, characterized in that, The composition includes the following components in parts by weight: 100 parts fluororubber, 20-25 parts silica, 5-10 parts calcium fluoride, 5-10 parts modified carbon nanotubes, 4-8 parts magnesium oxide (acid scavenger), 2-3 parts bisphenol AF (vulcanizing agent), 1-1.5 parts benzyltriphenylphosphine chloride (accelerator), and 0.5-1.5 parts processing aids. The method for preparing the modified carbon nanotubes includes the following steps: (1) Pretreated carbon nanotubes are obtained by reacting silane coupling agent with hydroxylated carbon nanotubes; (2) Mix the pretreated carbon nanotubes, deionized water and emulsifier, heat and stir to obtain a pre-emulsion; (3) In a nitrogen atmosphere, an initiator, methyl methacrylate and tridecyl fluorooctyl acrylate were added to the pre-emulsion, heated to react, cooled, demulsified, centrifuged, washed, vacuum dried and ground to obtain modified carbon nanotubes. The fluororubber comprises fluororubber A, fluororubber B, and fluororubber C in a mass ratio of (1.2-1.4):(0.4-0.6):(0.8-1.0); fluororubber A is copolymerized from vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene, with a Mooney viscosity of 15-80 MU at 121°C; fluororubber B is a copolymer of vinylidene fluoride and hexafluoropropylene, with a Mooney viscosity of 20-35 MU at 121°C; and fluororubber C is a bisphenol-cured copolymer, with a Mooney viscosity of 21-23 MU at 121°C.

2. The high-resistance fluororubber sealing material for battery electrolytes according to claim 1, characterized in that, The processing aid is polyethylene wax.

3. The method for preparing the high battery electrolyte resistant fluororubber sealing material according to any one of claims 1-2, characterized in that, The process includes the following steps: fluororubber is put into a mixer for plasticizing, followed by the sequential addition of silica, calcium fluoride, modified carbon nanotubes, acid absorber and some processing aids for primary mixing, the addition of the remaining components for secondary mixing, and then vulcanization to obtain a high-resistance fluororubber sealing material for battery electrolytes.