Furyl polyamide coating slurry for lithium battery diaphragm and preparation method of furyl polyamide coating slurry

Abstract

The invention discloses furyl polyamide coating slurry for a lithium battery diaphragm and a preparation method of the furyl polyamide coating slurry, and belongs to the technical field of furyl polyamide materials. The preparation method comprises the following steps: S1, preparing modified furyl polyamide; s2, the modified furyl polyamide and a solvent are mixed and stirred, a dispersing agent, a binding agent and a wetting agent are sequentially added, and uniform coating slurry is obtained through ultrasonic stirring treatment. The modified furyl polyamide is prepared from 2, 5-furandicarbonyl chloride, a diamine monomer and a modified monomer through a condensation polymerization reaction; the modified monomer is silicon-containing diamine. The prepared coating slurry is applied to the lithium battery diaphragm, and the obtained lithium battery diaphragm has excellent heat resistance and flexibility and can meet the use requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of furan-based polyamide materials, and in particular relates to a furan-based polyamide coating slurry for lithium battery diaphragms and a preparation method thereof. Background Art

[0002] With the widespread application of lithium-ion batteries in electric vehicles, energy storage systems and portable electronic devices, the requirements for their safety, energy density and cycle life are increasing. As an important component of the battery, lithium battery separators directly affect the performance and safety of the battery. Traditional lithium battery separators mainly use polyolefin materials (such as polyethylene (PE) and polypropylene (PP)). Although these materials have good electrochemical stability and mechanical strength, they have poor heat resistance and are prone to shrinkage or even melting in high temperature environments, resulting in internal short circuits in the battery and causing safety problems such as thermal runaway. In addition, the flexibility of polyolefin separators is limited, and they are easily mechanically damaged during battery assembly and use, affecting the long-term reliability of the battery. Therefore, the development of separator materials with excellent heat resistance and flexibility has become an important research direction in the field of lithium batteries.

[0003] In recent years, researchers have improved the performance of diaphragms by coating modification technology, that is, coating a functional coating on the surface of polyolefin diaphragms to improve their heat resistance, flexibility and electrolyte wettability. Commonly used coating materials include ceramic particles (such as Al 2 O 3 、SiO 2 ), polymers (such as polyvinylidene fluoride (PVDF)) and composite coating materials. However, although the ceramic coating can significantly improve the heat resistance of the diaphragm, its interface bonding with the polyolefin substrate is poor, it is easy to fall off, and the coating is not flexible enough; while the heat resistance of polymer coatings such as PVDF is limited, and it is difficult to meet the use requirements in high temperature environments.

[0004] Aromatic polyamides are a class of high-performance polymers with excellent thermal stability, mechanical strength and chemical stability. They are widely used in high-temperature filtration, protective materials and composite materials. The rigid aromatic ring structure in its molecular chain gives the material a high glass transition temperature and thermal decomposition temperature, allowing it to maintain stable physical and chemical properties in high temperature environments. However, the poor flexibility of traditional aromatic polyamides limits their application in lithium battery separators. Summary of the invention

[0005] The object of the present invention is to provide a furan-based polyamide coating slurry for lithium battery separators and a preparation method thereof, so as to solve the problem of poor heat resistance and flexibility of traditional lithium battery separators.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A method for preparing a furan-based polyamide coating slurry for a lithium battery separator comprises the following steps:

[0008] S1, preparing modified furan-based polyamide;

[0009] S2, mixing and stirring the modified furan-based polyamide and the solvent, adding a dispersant, a binder and a wetting agent in sequence, and subjecting the mixture to ultrasonic stirring to obtain a uniform coating slurry;

[0010] The modified furan-based polyamide is prepared by polycondensation of 2,5-furandicarboxylic acid chloride, a diamine monomer and a modified monomer; the modified monomer is a silicon-containing diamine, specifically one of 1,3-bis(3-aminopropyl)tetramethyldisiloxane, bis(3-aminopropyl)polydimethylsiloxane, 1,3-bis(4-aminophenyl)tetramethyldisiloxane and 1,3-bis(aminomethyl)tetramethyldisiloxane.

[0011] Further, the modified furan-based polyamide is prepared by the following steps:

[0012] S11, adding the modified diamine solution into the reactor, placing the reactor in an ice bath at 0-5° C., and introducing nitrogen into the reactor to exclude air;

[0013] S12, slowly dropping the 2,5-furandicarbonyl chloride solution into the reactor under ice bath conditions, controlling the dropping speed, and after the dropping is completed, continuing the reaction in the ice bath for 0.5-1 hour;

[0014] S13, removing the reactor from the ice bath, gradually heating up to 25-30° C., and continuing the reaction for 4-6 hours to obtain a reaction mixture;

[0015] S14, slowly pouring the reaction mixture into methanol and deionized water to precipitate the polymer;

[0016] S15. Collect the polymer precipitate by filtration, wash it with methanol and deionized water for 3-5 times, and then dry it in a vacuum drying oven at 60-70° C. for 24 hours to obtain a modified furan-based polyamide.

[0017] Further, the modified diamine solution in step S11 is prepared by the following steps:

[0018] Dissolving the diamine monomer and the modified monomer in N-methylpyrrolidone; adding triethylamine and stirring evenly to obtain a modified diamine solution;

[0019] The diamine monomer is one or more of 4,4'-diphenylmethanediamine, p-phenylenediamine and m-phenylenediamine;

[0020] The modified monomer is a silicon-containing diamine, specifically one of 1,3-bis(3-aminopropyl)tetramethyldisiloxane, bis(3-aminopropyl)polydimethylsiloxane, 1,3-bis(4-aminophenyl)tetramethyldisiloxane and 1,3-bis(aminomethyl)tetramethyldisiloxane.

[0021] Further, the 2,5-furandicarbonyl chloride solution in step S12 is prepared by the following steps:

[0022] Dissolve 2,5-furandicarboxylic acid chloride in N-methylpyrrolidone and stir evenly to obtain a 2,5-furandicarboxylic acid chloride solution.

[0023] Furthermore, the molar ratio of 2,5-furandicarboxylic acid chloride in the 2,5-furandicarboxylic acid chloride solution to the diamine monomer and the modified monomer in the modified diamine solution is 10-12:10:1.

[0024] Furthermore, the solvent in step S2 is selected from one of N-methylpyrrolidone, dimethylacetamide and deionized water; and the mass ratio of the modified furan-based polyamide to the solvent is 1:10-20.

[0025] Furthermore, the dispersant in step S2 is selected from one of polyacrylic acid, polyvinyl pyrrolidone and dodecyl phosphate, and the added amount is 0.5-2% of the total mass of the coating slurry.

[0026] Furthermore, the binder in step S2 is selected from one of polyvinylidene fluoride, sodium carboxymethyl cellulose and polyethyl acrylate, and the added amount is 2-5% of the total mass of the coating slurry.

[0027] Furthermore, the wetting agent in step S2 is selected from one of perfluorooctanoic acid, polyethylene glycol and polydimethylsiloxane, and the added amount is 0.1-1% of the total mass of the coating slurry.

[0028] A furan-based polyamide coating slurry for lithium battery separator is prepared by the above-mentioned preparation method.

[0029] Beneficial effects of the present invention:

[0030] (1) The present invention prepares a modified furan-based polyamide by polycondensation of 2,5-furandicarboxylic acid chloride, a diamine monomer and a silicon-containing diamine modified monomer; wherein the introduced silicon-containing diamine monomer molecular chain contains a plurality of siloxane units (-Si-O-Si-), which gives the material excellent flexibility and thermal stability; the prepared modified furan-based polyamide is further made into a coating slurry and applied to a lithium battery separator, which can give the lithium battery separator excellent heat resistance and flexibility.

[0031] (2) The present invention prepares a modified furan-based polyamide by adjusting the molar ratio of 2,5-furandicarboxylic acid chloride, a diamine monomer and a modified monomer through a condensation reaction; the modified furan-based polyamide is further made into a coating slurry and applied to a lithium battery separator, thereby successfully obtaining a lithium battery separator with excellent heat resistance and flexibility, and significantly improving the high temperature stability and mechanical properties of the separator. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] This embodiment provides a furan-based polyamide coating slurry for a lithium battery separator, which is prepared by the following steps:

[0035] S1, preparing modified furan-based polyamide;

[0036] S11, adding 10 mL of modified diamine solution into the reactor, placing the reactor in an ice bath at 0-5° C., and introducing nitrogen into the reactor to exclude air;

[0037] S12, slowly drop 10 mL of 2,5-furandicarbonyl chloride solution into the reactor under ice bath conditions, control the drop rate, and continue to react in the ice bath for 1 hour after the drop addition is completed;

[0038] S13, removing the reactor from the ice bath, gradually heating it to 28° C., and continuing the reaction for 6 hours to obtain a reaction mixture;

[0039] S14, slowly pouring the reaction mixture into methanol and deionized water to precipitate the polymer;

[0040] S15, collecting the polymer precipitate by filtration, washing it with methanol and deionized water for 5 times, and then drying it in a vacuum drying oven at 60° C. for 24 hours to obtain a modified furan-based polyamide;

[0041] S2, mixing the modified furan-based polyamide and N-methylpyrrolidone, adding polyacrylic acid, polyvinylidene fluoride and perfluorooctanoic acid in sequence, and stirring by ultrasonic for 1 hour to obtain a uniform coating slurry;

[0042] The mass ratio of the modified furan-based polyamide to N-methylpyrrolidone is 1:10, the amount of polyacrylic acid added is 1% of the total mass of the coating slurry, the amount of polyvinylidene fluoride added is 3% of the total mass of the coating slurry, and the amount of perfluorooctanoic acid added is 0.5% of the total mass of the coating slurry;

[0043] The modified diamine solution in step S11 is prepared by the following steps:

[0044] Dissolve 10 mmol of 4,4'-diphenylmethanediamine and 1 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane in 20 mL of N-methylpyrrolidone; add 2.5 mL of triethylamine and stir evenly to obtain a modified diamine solution;

[0045] The 2,5-furandicarbonyl chloride solution in step S12 is prepared by the following steps:

[0046] 10 mmol of 2,5-furandicarboxylic acid chloride was dissolved in 20 mL of N-methylpyrrolidone and stirred evenly to obtain a 2,5-furandicarboxylic acid chloride solution.

[0047] Example 2

[0048] This embodiment provides a furan-based polyamide coating slurry for a lithium battery separator, which is prepared by the following steps:

[0049] S1, preparing modified furan-based polyamide;

[0050] S11, adding 10 mL of modified diamine solution into the reactor, placing the reactor in an ice bath at 0-5° C., and introducing nitrogen into the reactor to exclude air;

[0051] S12, under ice bath conditions, slowly drop 11 mL of 2,5-furandicarbonyl chloride solution into the reactor, control the drop rate, and after the drop addition is completed, continue to react in the ice bath for 1 hour;

[0052] S13, removing the reactor from the ice bath, gradually heating it to 28° C., and continuing the reaction for 6 hours to obtain a reaction mixture;

[0053] S14, slowly pouring the reaction mixture into methanol and deionized water to precipitate the polymer;

[0054] S15, collecting the polymer precipitate by filtration, washing it with methanol and deionized water for 5 times, and then drying it in a vacuum drying oven at 60° C. for 24 hours to obtain a modified furan-based polyamide;

[0055] S2, mixing the modified furan-based polyamide and N-methylpyrrolidone, adding polyacrylic acid, polyvinylidene fluoride and perfluorooctanoic acid in sequence, and stirring by ultrasonic for 1 hour to obtain a uniform coating slurry;

[0056] The mass ratio of the modified furan-based polyamide to N-methylpyrrolidone is 1:10, the amount of polyacrylic acid added is 1% of the total mass of the coating slurry, the amount of polyvinylidene fluoride added is 3% of the total mass of the coating slurry, and the amount of perfluorooctanoic acid added is 0.5% of the total mass of the coating slurry;

[0057] The modified diamine solution in step S11 is prepared by the following steps:

[0058] Dissolve 10 mmol of 4,4'-diphenylmethanediamine and 1 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane in 20 mL of N-methylpyrrolidone; add 2.5 mL of triethylamine and stir evenly to obtain a modified diamine solution;

[0059] The 2,5-furandicarbonyl chloride solution in step S12 is prepared by the following steps:

[0060] 10 mmol of 2,5-furandicarboxylic acid chloride was dissolved in 20 mL of N-methylpyrrolidone and stirred evenly to obtain a 2,5-furandicarboxylic acid chloride solution.

[0061] Example 3

[0062] This embodiment provides a furan-based polyamide coating slurry for a lithium battery separator, which is prepared by the following steps:

[0063] S1, preparing modified furan-based polyamide;

[0064] S11, adding 10 mL of modified diamine solution into the reactor, placing the reactor in an ice bath at 0-5° C., and introducing nitrogen into the reactor to exclude air;

[0065] S12, slowly drop 12 mL of 2,5-furandicarbonyl chloride solution into the reactor under ice bath conditions, control the drop rate, and continue to react in the ice bath for 1 hour after the drop addition is completed;

[0066] S13, removing the reactor from the ice bath, gradually heating it to 28° C., and continuing the reaction for 6 hours to obtain a reaction mixture;

[0067] S14, slowly pouring the reaction mixture into methanol and deionized water to precipitate the polymer;

[0068] S15, collecting the polymer precipitate by filtration, washing it with methanol and deionized water for 5 times, and then drying it in a vacuum drying oven at 60° C. for 24 hours to obtain a modified furan-based polyamide;

[0069] S2, mixing the modified furan-based polyamide and N-methylpyrrolidone, adding polyacrylic acid, polyvinylidene fluoride and perfluorooctanoic acid in sequence, and stirring by ultrasonic for 1 hour to obtain a uniform coating slurry;

[0070] The mass ratio of the modified furan-based polyamide to N-methylpyrrolidone is 1:10, the amount of polyacrylic acid added is 1% of the total mass of the coating slurry, the amount of polyvinylidene fluoride added is 3% of the total mass of the coating slurry, and the amount of perfluorooctanoic acid added is 0.5% of the total mass of the coating slurry;

[0071] The modified diamine solution in step S11 is prepared by the following steps:

[0072] Dissolve 10 mmol of 4,4'-diphenylmethanediamine and 1 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane in 20 mL of N-methylpyrrolidone; add 2.5 mL of triethylamine and stir evenly to obtain a modified diamine solution;

[0073] The 2,5-furandicarbonyl chloride solution in step S12 is prepared by the following steps:

[0074] 10 mmol of 2,5-furandicarboxylic acid chloride was dissolved in 20 mL of N-methylpyrrolidone and stirred evenly to obtain a 2,5-furandicarboxylic acid chloride solution.

[0075] Example 4

[0076] This embodiment provides a furan-based polyamide coating slurry for a lithium battery separator, which is prepared by the following steps:

[0077] S1, preparing modified furan-based polyamide;

[0078] S11, adding 10 mL of modified diamine solution into the reactor, placing the reactor in an ice bath at 0-5° C., and introducing nitrogen into the reactor to exclude air;

[0079] S12, slowly drop 12 mL of 2,5-furandicarbonyl chloride solution into the reactor under ice bath conditions, control the drop rate, and continue to react in the ice bath for 1 hour after the drop addition is completed;

[0080] S13, removing the reactor from the ice bath, gradually heating it to 28° C., and continuing the reaction for 6 hours to obtain a reaction mixture;

[0081] S14, slowly pouring the reaction mixture into methanol and deionized water to precipitate the polymer;

[0082] S15, collecting the polymer precipitate by filtration, washing it with methanol and deionized water for 5 times, and then drying it in a vacuum drying oven at 60° C. for 24 hours to obtain a modified furan-based polyamide;

[0083] S2, mixing the modified furan-based polyamide and N-methylpyrrolidone, adding polyacrylic acid, polyvinylidene fluoride and perfluorooctanoic acid in sequence, and stirring by ultrasonic for 1 hour to obtain a uniform coating slurry;

[0084] The mass ratio of the modified furan-based polyamide to N-methylpyrrolidone is 1:15, the amount of polyacrylic acid added is 1% of the total mass of the coating slurry, the amount of polyvinylidene fluoride added is 3% of the total mass of the coating slurry, and the amount of perfluorooctanoic acid added is 0.5% of the total mass of the coating slurry;

[0085] The modified diamine solution in step S11 is prepared by the following steps:

[0086] Dissolve 10 mmol of 4,4'-diphenylmethanediamine and 1 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane in 20 mL of N-methylpyrrolidone; add 2.5 mL of triethylamine and stir evenly to obtain a modified diamine solution;

[0087] The 2,5-furandicarbonyl chloride solution in step S12 is prepared by the following steps:

[0088] 10 mmol of 2,5-furandicarboxylic acid chloride was dissolved in 20 mL of N-methylpyrrolidone and stirred evenly to obtain a 2,5-furandicarboxylic acid chloride solution.

[0089] Example 5

[0090] This embodiment provides a furan-based polyamide coating slurry for a lithium battery separator, which is prepared by the following steps:

[0091] S1, preparing modified furan-based polyamide;

[0092] S11, adding 10 mL of modified diamine solution into the reactor, placing the reactor in an ice bath at 0-5° C., and introducing nitrogen into the reactor to exclude air;

[0093] S12, slowly drop 12 mL of 2,5-furandicarbonyl chloride solution into the reactor under ice bath conditions, control the drop rate, and continue to react in the ice bath for 1 hour after the drop addition is completed;

[0094] S13, removing the reactor from the ice bath, gradually heating it to 28° C., and continuing the reaction for 6 hours to obtain a reaction mixture;

[0095] S14, slowly pouring the reaction mixture into methanol and deionized water to precipitate the polymer;

[0096] S15, collecting the polymer precipitate by filtration, washing it with methanol and deionized water for 5 times, and then drying it in a vacuum drying oven at 60° C. for 24 hours to obtain a modified furan-based polyamide;

[0097] S2, mixing the modified furan-based polyamide and N-methylpyrrolidone, adding polyacrylic acid, polyvinylidene fluoride and perfluorooctanoic acid in sequence, and stirring by ultrasonic for 1 hour to obtain a uniform coating slurry;

[0098] The mass ratio of the modified furan-based polyamide to N-methylpyrrolidone is 1:20, the amount of polyacrylic acid added is 1% of the total mass of the coating slurry, the amount of polyvinylidene fluoride added is 3% of the total mass of the coating slurry, and the amount of perfluorooctanoic acid added is 0.5% of the total mass of the coating slurry;

[0099] The modified diamine solution in step S11 is prepared by the following steps:

[0100] Dissolve 10 mmol of 4,4'-diphenylmethanediamine and 1 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane in 20 mL of N-methylpyrrolidone; add 2.5 mL of triethylamine and stir evenly to obtain a modified diamine solution;

[0101] The 2,5-furandicarbonyl chloride solution in step S12 is prepared by the following steps:

[0102] 10 mmol of 2,5-furandicarboxylic acid chloride was dissolved in 20 mL of N-methylpyrrolidone and stirred evenly to obtain a 2,5-furandicarboxylic acid chloride solution.

[0103] Comparative Example 1

[0104] This comparative example provides a furan-based polyamide coating slurry for a lithium battery separator, which is prepared by the following steps:

[0105] S1, preparing modified furan-based polyamide;

[0106] S11, adding 10 mL of modified diamine solution into the reactor, placing the reactor in an ice bath at 0-5° C., and introducing nitrogen into the reactor to exclude air;

[0107] S12, slowly drop 8 mL of 2,5-furandicarbonyl chloride solution into the reactor under ice bath conditions, control the drop rate, and continue to react in the ice bath for 1 hour after the drop addition is completed;

[0108] S13, removing the reactor from the ice bath, gradually heating it to 28° C., and continuing the reaction for 6 hours to obtain a reaction mixture;

[0109] S14, slowly pouring the reaction mixture into methanol and deionized water to precipitate the polymer;

[0110] S15, collecting the polymer precipitate by filtration, washing it with methanol and deionized water for 5 times, and then drying it in a vacuum drying oven at 60° C. for 24 hours to obtain a modified furan-based polyamide;

[0111] S2, mixing the modified furan-based polyamide and N-methylpyrrolidone, adding polyacrylic acid, polyvinylidene fluoride and perfluorooctanoic acid in sequence, and stirring by ultrasonic for 1 hour to obtain a uniform coating slurry;

[0112] The mass ratio of the modified furan-based polyamide to N-methylpyrrolidone is 1:10, the amount of polyacrylic acid added is 1% of the total mass of the coating slurry, the amount of polyvinylidene fluoride added is 3% of the total mass of the coating slurry, and the amount of perfluorooctanoic acid added is 0.5% of the total mass of the coating slurry;

[0113] The modified diamine solution in step S11 is prepared by the following steps:

[0114] Dissolve 10 mmol of 4,4'-diphenylmethanediamine and 1 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane in 20 mL of N-methylpyrrolidone; add 2.5 mL of triethylamine and stir evenly to obtain a modified diamine solution;

[0115] The 2,5-furandicarbonyl chloride solution in step S12 is prepared by the following steps:

[0116] 10 mmol of 2,5-furandicarboxylic acid chloride was dissolved in 20 mL of N-methylpyrrolidone and stirred evenly to obtain a 2,5-furandicarboxylic acid chloride solution.

[0117] Comparative Example 2

[0118] This comparative example provides a furan-based polyamide coating slurry for a lithium battery separator, which is prepared by the following steps:

[0119] S1, preparing modified furan-based polyamide;

[0120] S11, adding 10 mL of modified diamine solution into the reactor, placing the reactor in an ice bath at 0-5° C., and introducing nitrogen into the reactor to exclude air;

[0121] S12, under ice bath conditions, slowly drop 14 mL of 2,5-furandicarbonyl chloride solution into the reactor, control the drop rate, and after the drop addition is completed, continue to react in the ice bath for 1 hour;

[0122] S13, removing the reactor from the ice bath, gradually heating it to 28° C., and continuing the reaction for 6 hours to obtain a reaction mixture;

[0123] S14, slowly pouring the reaction mixture into methanol and deionized water to precipitate the polymer;

[0124] S15, collecting the polymer precipitate by filtration, washing it with methanol and deionized water for 5 times, and then drying it in a vacuum drying oven at 60° C. for 24 hours to obtain a modified furan-based polyamide;

[0125] S2, mixing the modified furan-based polyamide and N-methylpyrrolidone, adding polyacrylic acid, polyvinylidene fluoride and perfluorooctanoic acid in sequence, and stirring by ultrasonic for 1 hour to obtain a uniform coating slurry;

[0126] The mass ratio of the modified furan-based polyamide to N-methylpyrrolidone is 1:10, the amount of polyacrylic acid added is 1% of the total mass of the coating slurry, the amount of polyvinylidene fluoride added is 3% of the total mass of the coating slurry, and the amount of perfluorooctanoic acid added is 0.5% of the total mass of the coating slurry;

[0127] The modified diamine solution in step S11 is prepared by the following steps:

[0128] Dissolve 10 mmol of 4,4'-diphenylmethanediamine and 1 mmol of 1,3-bis(3-aminopropyl)tetramethyldisiloxane in 20 mL of N-methylpyrrolidone; add 2.5 mL of triethylamine and stir evenly to obtain a modified diamine solution;

[0129] The 2,5-furandicarbonyl chloride solution in step S12 is prepared by the following steps:

[0130] 10 mmol of 2,5-furandicarboxylic acid chloride was dissolved in 20 mL of N-methylpyrrolidone and stirred evenly to obtain a 2,5-furandicarboxylic acid chloride solution.

[0131] Comparative Example 3

[0132] This comparative example provides a furan-based polyamide coating slurry for a lithium battery separator, which is prepared by the following steps:

[0133] S1, preparing furan-based polyamide;

[0134] S11, adding 10 mL of diamine solution into the reactor, placing the reactor in an ice bath at 0-5° C., and introducing nitrogen into the reactor to exclude air;

[0135] S12, slowly drop 10 mL of 2,5-furandicarbonyl chloride solution into the reactor under ice bath conditions, control the drop rate, and continue to react in the ice bath for 1 hour after the drop addition is completed;

[0136] S13, removing the reactor from the ice bath, gradually heating it to 28° C., and continuing the reaction for 6 hours to obtain a reaction mixture;

[0137] S14, slowly pouring the reaction mixture into methanol and deionized water to precipitate the polymer;

[0138] S15, collecting the polymer precipitate by filtration, washing it with methanol and deionized water for 5 times, and then drying it in a vacuum drying oven at 60° C. for 24 hours to obtain a furan-based polyamide;

[0139] S2, mixing furan-based polyamide and N-methylpyrrolidone, adding polyacrylic acid, polyvinylidene fluoride and perfluorooctanoic acid in sequence, and stirring by ultrasonic for 1 hour to obtain a uniform coating slurry;

[0140] The mass ratio of furanyl polyamide to N-methylpyrrolidone is 1:10, the amount of polyacrylic acid added is 1% of the total mass of the coating slurry, the amount of polyvinylidene fluoride added is 3% of the total mass of the coating slurry, and the amount of perfluorooctanoic acid added is 0.5% of the total mass of the coating slurry;

[0141] The diamine solution in step S11 is prepared by the following steps:

[0142] Dissolve 10 mmol of 4,4'-diphenylmethanediamine in 20 mL of N-methylpyrrolidone; add 2.5 mL of triethylamine and stir evenly to obtain a diamine solution;

[0143] The 2,5-furandicarbonyl chloride solution in step S12 is prepared by the following steps:

[0144] 10 mmol of 2,5-furandicarboxylic acid chloride was dissolved in 20 mL of N-methylpyrrolidone and stirred evenly to obtain a 2,5-furandicarboxylic acid chloride solution.

[0145] The coating slurries prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were coated on a lithium battery separator substrate; the coating was performed by blade coating; after coating, the slurries were pre-dried at 60 to 80° C. for 5 to 10 minutes to remove most of the solvent; the coated separator was cured at 120° C. for 1 hour to ensure that the coating was completely dried and formed a stable structure, thereby obtaining a coated separator;

[0146] The obtained coated diaphragm was subjected to heat shrinkage test and flexibility test respectively, and the results are shown in Table 1:

[0147] Table 1

[0148]

[0149]

[0150] It can be seen from Table 1 that when the coating slurries prepared in Examples 1 to 5 are used for lithium battery separators, the obtained coated separators have low thermal shrinkage, high tensile strength and high elongation at break, indicating that the coating slurry prepared in the present invention can make the lithium battery separator have excellent heat resistance and flexibility.

[0151] The molar ratio of 2,5-furandicarboxylic acid chloride, diamine monomer and modified monomer in Comparative Examples 1 and 2 exceeds the scope of the present invention. Compared with Example 1, when the obtained coating slurry is used for lithium battery separators, the obtained coated separators have higher thermal shrinkage, and lower tensile strength and elongation at break, indicating that the molar ratio of 2,5-furandicarboxylic acid chloride, diamine monomer and modified monomer of the present invention cannot be changed at will; compared with the example, no modified monomer is added in Comparative Example 3. When the obtained coating slurry is used for lithium battery separators, the obtained coated separators have the highest thermal shrinkage, and the lowest tensile strength and elongation at break.

[0152] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities and operations. Moreover, the terms "include", "comprise" and any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, and also includes elements inherent to such process, method, article or device.

[0153] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a furan-based polyamide coating slurry for a lithium battery separator, characterized in that: The following steps are involved: S1, preparing modified furan-based polyamide; S2, mixing and stirring the modified furan-based polyamide and the solvent, adding a dispersant, a binder and a wetting agent in sequence, and subjecting the mixture to ultrasonic stirring to obtain a uniform coating slurry; The modified furan-based polyamide is prepared by polycondensation of 2,5-furandicarboxylic acid chloride, a diamine monomer and a modified monomer; the modified monomer is a silicon-containing diamine, specifically one of 1,3-bis(3-aminopropyl)tetramethyldisiloxane, bis(3-aminopropyl)polydimethylsiloxane, 1,3-bis(4-aminophenyl)tetramethyldisiloxane and 1,3-bis(aminomethyl)tetramethyldisiloxane.

2. The method for preparing a furan-based polyamide coating slurry for a lithium battery separator according to claim 1, characterized in that: The modified furan-based polyamide is prepared by the following steps: S11, adding a modified diamine solution into a reactor, placing the reactor in an ice bath at 0-5° C., and introducing nitrogen into the reactor; S12, under ice bath conditions, adding the 2,5-furandicarbonyl chloride solution dropwise to the reactor, and after the addition is complete, continuing the reaction in the ice bath for 0.5-1 hour; S13, removing the reactor from the ice bath, gradually heating up to 25-30° C., and continuing the reaction for 4-6 hours to obtain a reaction mixture; S14, pouring the reaction mixture into methanol and deionized water to precipitate the polymer; S15. Collect the polymer precipitate by filtration, wash it with methanol and deionized water for 3-5 times, and then dry it in a vacuum drying oven at 60-70° C. for 24 hours to obtain a modified furan-based polyamide.

3. The method for preparing a furan-based polyamide coating slurry for a lithium battery separator according to claim 2, characterized in that: The modified diamine solution in step S11 is prepared by the following steps: Dissolving the diamine monomer and the modified monomer in N-methylpyrrolidone; adding triethylamine and stirring evenly to obtain a modified diamine solution; The diamine monomer is one or more of 4,4'-diphenylmethanediamine, p-phenylenediamine and m-phenylenediamine.

4. The method for preparing a furan-based polyamide coating slurry for a lithium battery separator according to claim 2, characterized in that: The 2,5-furandicarbonyl chloride solution in step S12 is prepared by the following steps: Dissolve 2,5-furandicarboxylic acid chloride in N-methylpyrrolidone and stir evenly to obtain a 2,5-furandicarboxylic acid chloride solution.

5. The method for preparing a furan-based polyamide coating slurry for a lithium battery separator according to claim 2, characterized in that: The molar ratio of 2,5-furandicarboxylic acid chloride in the 2,5-furandicarboxylic acid chloride solution and the diamine monomer to the modified monomer in the modified diamine solution is 10-12:10:

1.

6. The method for preparing a furan-based polyamide coating slurry for a lithium battery separator according to claim 1, characterized in that: The solvent in step S2 is selected from one of N-methylpyrrolidone, dimethylacetamide and deionized water; the mass ratio of the modified furan-based polyamide to the solvent is 1:10-20.

7. The method for preparing a furan-based polyamide coating slurry for a lithium battery separator according to claim 1, characterized in that: In step S2, the dispersant is selected from one of polyacrylic acid, polyvinyl pyrrolidone and dodecyl phosphate, and the added amount is 0.5-2% of the total mass of the coating slurry.

8. The method for preparing a furan-based polyamide coating slurry for a lithium battery separator according to claim 1, characterized in that: In step S2, the binder is selected from one of polyvinylidene fluoride, sodium carboxymethyl cellulose and polyethyl acrylate, and the added amount is 2-5% of the total mass of the coating slurry.

9. The method for preparing a furan-based polyamide coating slurry for a lithium battery separator according to claim 1, characterized in that: The wetting agent in step S2 is selected from one of perfluorooctanoic acid, polyethylene glycol and polydimethylsiloxane, and the added amount is 0.1-1% of the total mass of the coating slurry.

10. A furan-based polyamide coating slurry for lithium battery separator, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 9.

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