A battery separator, its preparation method and application

Abstract

This invention relates to the field of lithium battery technology, specifically to a battery separator, its preparation method, and its applications. The preparation method includes: first mixing an organic solvent with thiophene-based polyamide, then adding an emulsifier and an adhesive for a second mixing. This battery separator applies thiophene-based polyamide to the field of lithium battery separators, resulting in a lithium battery coated separator with advantages such as low thermal shrinkage and good wettability. Adhesive A is also used to improve the adhesion of the battery separator. Furthermore, due to the high temperature resistance, high strength, and inherent adhesive properties of polyamide, the resulting lithium battery coated separator also exhibits better safety. In addition, the thiophene-based polyamide coating solution of this invention has a simple and readily available raw material composition, an easy-to-operate preparation method, low cost, and is environmentally friendly, thus possessing broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, specifically to a battery separator, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries are characterized by high energy density and long cycle efficiency, leading to increasing demand in the new energy sector. The lithium-ion battery separator is a crucial component, playing a vital role in battery safety.

[0003] Polyolefin separators are currently the most widely used lithium-ion battery separators. However, due to inherent material properties and manufacturing processes, polyolefin separators suffer from problems such as high thermal shrinkage, low rupture temperature, and low lithium-ion transport efficiency. Currently, polyethylene and polypropylene separators are the most widely used, but both materials soften and deform at around 120°C, limiting battery safety. To improve the heat resistance and wettability of polyolefin separators, the main approach is to coat the surface with inorganic or organic materials, such as ceramic, PVDF, or aramid coatings. However, ceramic or PVDF coatings offer limited improvement in thermal performance; aramid coatings suffer from issues such as gelation, short raw material shelf life, low processing yield, weak coating adhesion, and easy powdering and detachment, potentially leading to battery safety incidents.

[0004] To address the performance defects of diaphragms and meet the demands of low-carbon and green development, it is of great significance to develop bio-based organic coating materials with good thermal stability and high mechanical properties. Summary of the Invention

[0005] The purpose of this invention is to address the performance defects of existing polyolefin lithium battery separators, thereby providing a battery separator, its preparation method, and its applications. This battery separator utilizes thiophene-based polyamide in the field of lithium battery separators, resulting in a lithium battery coated separator with advantages such as low thermal shrinkage and good wettability. Adhesive A is also used to enhance the battery separator's adhesion. Furthermore, due to the high strength and heat resistance of polyamide, which inherently possesses adhesive properties, the resulting lithium battery coated separator also exhibits improved safety. In addition, the thiophene-based polyamide coating solution of this invention has a simple and readily available raw material composition, an easy-to-operate preparation method, low cost, and is environmentally friendly, thus possessing broad application prospects.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a thiophene-based polyamide coating liquid, the method comprising: first mixing an organic solvent with thiophene-based polyamide, and then adding nano-ceramic particles, an emulsifier and an adhesive for a second mixing.

[0007] Furthermore, the thiophene polyamide is composed of a diacyl chloride monomer and a diamine monomer.

[0008] Furthermore, the diacyl chloride monomer is selected from one or more of thiophene dicarboxylate chloride, comonomers composed of thiophene dicarboxylate chloride and aromatic diacyl chloride, comonomers composed of thiophene dicarboxylate chloride and heterocyclic diacyl chloride, and comonomers composed of thiophene dicarboxylate chloride and aliphatic diacyl chloride; the diamine monomer is selected from one or more of aryl diamine, aliphatic diamine, and heterocyclic diamine.

[0009] Furthermore, the diacyl chloride monomer is selected from one or more of naphthalenedicarboxyl chloride, isophthaloyl chloride, 1,3,5-benzenetricarboxyl chloride, 2,5-furandicarboxyl chloride, terephthaloyl chloride, piperidinedicarboxyl chloride, and pyridinedicarboxyl chloride.

[0010] Furthermore, the diamine monomer is selected from one or more of 2-(4-aminophenyl)-5-aminobenzoxazole, 4,4'-(1,4-phenyldioxy)bisphenylamine, 2-(4-aminophenyl)-5-aminobenzimidazole, 3,4-diaminodiphenyl ether, butanediamine, pentanediamine, hexanediamine, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3-diaminodiphenyl sulfone, m-phenylenediamine, 9,9-bis(4-aminophenyl)fluorene, naphthyldiamine, p-phenylenediamine, 4,4-diaminodiphenyl ether, 2,2'-bis(trifluoromethyl)diaminobiphenyl, 4,4-diaminodiphenyl sulfone, ethylenediamine, propylenediamine, nonanediamine, 4,4'-bis3-aminophenoxydiphenyl sulfone, and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane.

[0011] Furthermore, the general structural formula of the thiophene polyamide is shown in Formulas I-VI.

[0012] ,

[0013] ,

[0014] ,

[0015] ,

[0016] ,

[0017] ;

[0018] in,

[0019] X and Y are each independently selected from one of H, alkyl, halogen atom, amino, amino-derived group, hydroxyl and hydroxyl-derived group;

[0020] m≥1 and is an integer, h≥1 and is an integer, n≥1 and is an integer, k≥1 and is an integer;

[0021] R', R'' and R''' are each independently selected from one of the following groups: alkyl, phenyl, bridged ring group, spirocyclic group and heterocyclic group.

[0022] Furthermore, the organic solvent is selected from one or more of N-methylpyrrolidone, N-ethylpyrrolidone, γ-valerolactone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, and ethylene glycol dimethyl ether.

[0023] Furthermore, the emulsifier is selected from one or more of sodium thiophene dicarboxylate, sodium succinate, sodium p-benzenesulfonate, lithium succinate, lithium p-benzenesulfonate, and sodium dodecyl sulfonate.

[0024] Furthermore, the adhesive is selected from one or more of adhesive A, a mixture of adhesive A and PVDF, a mixture of adhesive A and copolyvinyl acetate, and a mixture of adhesive A and styrene-butadiene rubber.

[0025] Furthermore, the nano-ceramic particles are selected from one or more of alumina, magnesium oxide, zinc oxide, aluminum hydroxide, and silicon dioxide.

[0026] Furthermore, the particle size of the nano-ceramic particles is 300~500nm.

[0027] Furthermore, the organic solvent, thiophene polyamide, nano-ceramic particles, emulsifier, and adhesive are composed of the following weight parts: 6-30 parts of thiophene polyamide, 50-150 parts of organic solvent, 10-30 parts of nano-ceramic particles, 2-10 parts of emulsifier, and 1-10 parts of adhesive.

[0028] Furthermore, the conditions for the first mixing include: a temperature of 15~30℃, a time of 0.5~2h, and a stirring rate of 150~300rpm.

[0029] Furthermore, the conditions for the second mixing include: a temperature of 15~30℃, a time of 1~3h, and a stirring rate of 150~300rpm.

[0030] Furthermore, the adhesive A is a zinc carboxylate salt of a polyarylene composed of a first monomer, a second monomer, and zinc hydroxide.

[0031] Furthermore, the structural formula of the first monomer is shown in formula (a):

[0032] ;

[0033] The second monomer is butadiene.

[0034] Furthermore, the preparation method of adhesive A includes:

[0035] 1) In the presence of the first solvent, the first monomer is mixed with zinc hydroxide and reacted, then distilled under reduced pressure and dried to obtain the zinc carboxylate salt of the first monomer;

[0036] 2) In the presence of the second solvent, the zinc carboxylate salt of the first monomer obtained in step 1) is mixed with the second monomer, and then tetramethylethylenediamine and n-butyllithium are added to initiate polymerization;

[0037] The structural formula of the first monomer is shown in formula (a):

[0038] ;

[0039] The second monomer is butadiene.

[0040] Furthermore, in step 1), the first solvent is a mixed solution of ethanol and water, with a mass ratio of ethanol to water of 1~2:1.

[0041] Furthermore, in step 1), the conditions for the mixing reaction include: a temperature of 40~60℃ and a time of 1~3h.

[0042] Furthermore, in step 1), the mass ratio of the first monomer to zinc hydroxide is 1:0.2~0.6.

[0043] Furthermore, in step 2), the second solvent is tetrahydrofuran.

[0044] Furthermore, in step 2), the mass ratio of the zinc carboxylate salt of the first monomer to the second monomer is 1:0.2~0.6.

[0045] Furthermore, in step 2), the mixing conditions include: under anaerobic conditions, a stirring rate of 150~300 rpm and a temperature of 40~50℃.

[0046] Furthermore, in step 2), 5-10 mmol of tetramethylethylenediamine and 5-10 mmol of n-butyllithium are added per 100g of butadiene.

[0047] Furthermore, in step 2), the polymerization conditions include: under a nitrogen atmosphere and / or an argon atmosphere, a polymerization temperature of 30~60℃, and a time of 4~8h.

[0048] In a second aspect, the present invention provides an application of a thiophene-based polyamide coating liquid in the preparation of a lithium battery separator, wherein the thiophene-based polyamide coating liquid is the thiophene-based polyamide coating liquid prepared by the preparation method described in the first aspect.

[0049] Thirdly, the present invention provides a method for preparing a lithium battery separator, the method comprising: coating a thiophene-based polyamide coating solution onto one or both sides of a base film, performing coagulation bath extraction, and drying; wherein,

[0050] The thiophene polyamide coating liquid is the thiophene polyamide coating liquid prepared by the preparation method described in the first aspect;

[0051] The coating thickness is 0.5~4μm;

[0052] The base film is a polyethylene base film or a polypropylene base film.

[0053] In the above technical solution, the thiophene-based polyamide coating solution of the present invention comprises only an organic solvent, thiophene-based polyamide, an emulsifier, and an adhesive, resulting in a simple composition and low cost. Furthermore, thiophene-based polyamide is a bio-based material with widely available, sustainable, and renewable raw materials, exhibiting green and environmentally friendly characteristics. In addition, the lithium battery separator prepared by the thiophene-based polyamide coating solution of the present invention has the advantages of low thermal shrinkage and good wettability, and because thiophene-based polyamide has inherent adhesive properties, it also offers better safety.

[0054] Furthermore, the thiophene-based polyamide coating solution of the present invention uses adhesive A. Adhesive A introduces carboxyl groups into its structure. The carboxyl oxygen forms hydrogen bonds with the amide bonds of the thiophene-based polyamide, enhancing the bonding force. The high polarity of the carboxyl groups further enhances the bonding force with the base film. Adhesive A also possesses good heat resistance and higher strength because it introduces zinc metal elements into its structure. The introduction of inorganic materials enhances its rigidity and hardness, thereby making the dimensions of the separator more stable. At the same time, the zinc element and the thiophene cyclosulfide element form a strong bonding force through covalent and coordinate bonds. Adhesive A generates strong adhesion between itself, the thiophene polyamide, and the base film. Adhesive A has good bonding properties. It acts as a bridge, bonding the base film on one hand and the thiophene-based polyamide on the other, making the coating solution more firmly bonded to the base film and improving the safety of the battery.

[0055] Meanwhile, the preparation steps of the thiophene-based polyamide coating liquid of the present invention are simple, the reaction conditions are mild, the cost is low and it is environmentally friendly, making it suitable for large-scale industrial production and with broad application prospects.

[0056] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0057] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0058] Figure 1This is the NMR spectrum of compound 3 of the present invention;

[0059] Figure 2 This is the NMR spectrum of compound 4 of the present invention;

[0060] Figure 3 The NMR spectrum of compound 7 of this invention;

[0061] Figure 4 This is the NMR spectrum of compound 10 of the present invention. Detailed Implementation

[0062] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0063] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0064] In a first aspect, the present invention provides a method for preparing a thiophene-based polyamide coating liquid, the method comprising: first mixing an organic solvent with thiophene-based polyamide, and then adding nano-ceramic particles, an emulsifier and an adhesive for a second mixing.

[0065] The thiophene-based polyamide coating solution of this invention comprises only an organic solvent, thiophene-based polyamide, an emulsifier, and an adhesive, resulting in a simple composition and low cost. Furthermore, thiophene-based polyamide is a bio-based material with widely available, sustainable, and renewable raw materials, exhibiting green and environmentally friendly characteristics. In addition, the lithium battery separator prepared with the thiophene-based polyamide coating solution of this invention has the advantages of low thermal shrinkage and good wettability, and because thiophene-based polyamide has inherent adhesive properties, it also offers better safety.

[0066] In a preferred embodiment of the present invention, the thiophene polyamide is composed of a diacyl chloride monomer and a diamine monomer.

[0067] In a preferred embodiment of the present invention, the molar ratio of the diacyl chloride monomer to the diamine monomer is 1:1.

[0068] In a preferred embodiment of the present invention, the diacyl chloride monomer is selected from one or more of the following: thiophene dicarboxylate chloride, a comonomer composed of thiophene dicarboxylate chloride and aromatic diacyl chloride, a comonomer composed of thiophene dicarboxylate chloride and heterocyclic diacyl chloride, and a comonomer composed of thiophene dicarboxylate chloride and aliphatic diacyl chloride.

[0069] In a preferred embodiment of the present invention, the diamine monomer is selected from one or more of aryl diamines, aliphatic diamines, and heterocyclic diamines.

[0070] In a preferred embodiment of the present invention, the diacyl chloride monomer is selected from one or more of naphthalenedicarboxyl chloride, isophthaloyl chloride, 1,3,5-benzenetricarboxyl chloride, 2,5-furandicarboxyl chloride, terephthaloyl chloride, piperidinedicarboxyl chloride, and pyridinedicarboxyl chloride.

[0071] In a preferred embodiment of the present invention, the diamine monomer is selected from one or more of 2-(4-aminophenyl)-5-aminobenzoxazole, 4,4'-(1,4-phenyldioxy)bisphenylamine, 2-(4-aminophenyl)-5-aminobenzimidazole, 3,4-diaminodiphenyl ether, butanediamine, pentanediamine, hexamethylenediamine, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3-diaminodiphenyl sulfone, m-phenylenediamine, 9,9-bis(4-aminophenyl)fluorene, naphthyldiamine, p-phenylenediamine, 4,4-diaminodiphenyl ether, 2,2'-bis(trifluoromethyl)diaminobiphenyl, 4,4-diaminodiphenyl sulfone, ethylenediamine, propylenediamine, nonanediamine, 4,4'-bis3-aminophenoxydiphenyl sulfone, and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane.

[0072] In a preferred embodiment of the present invention, the thiophene polyamide has the general structural formulas shown in Formulas I-VI.

[0073] ,

[0074] ,

[0075] ,

[0076] ,

[0077] ,

[0078] ;

[0079] in,

[0080] X and Y are each independently selected from one of H, alkyl, halogen atom, amino, amino-derived group, hydroxyl and hydroxyl-derived group;

[0081] m≥1 and is an integer, h≥1 and is an integer, n≥1 and is an integer, k≥1 and is an integer;

[0082] R', R'' and R''' are each independently selected from one of the following groups: alkyl, phenyl, bridged ring group, spirocyclic group and heterocyclic group.

[0083] In a preferred embodiment of the present invention, the organic solvent is selected from one or more of N-methylpyrrolidone, N-ethylpyrrolidone, γ-valerolactone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, and ethylene glycol dimethyl ether.

[0084] In a preferred embodiment of the present invention, the emulsifier is selected from one or more of sodium thiophene dicarboxylate, sodium succinate, sodium p-benzenesulfonate, lithium succinate, lithium p-benzenesulfonate, and sodium dodecyl sulfonate.

[0085] In a preferred embodiment of the present invention, the adhesive is selected from one or more of adhesive A, a mixture of adhesive A and PVDF, a mixture of adhesive A and copolyvinyl acetate, and a mixture of adhesive A and styrene-butadiene rubber.

[0086] In a preferred embodiment of the present invention, the nano-ceramic particles are selected from one or more of alumina, magnesium oxide, zinc oxide, aluminum hydroxide, and silicon dioxide.

[0087] In a preferred embodiment of the present invention, the particle size of the nano-ceramic particles is 300~500nm.

[0088] In a preferred embodiment of the present invention, the weight proportions of the organic solvent, thiophene polyamide, nano-ceramic particles, emulsifier, and adhesive are as follows: 6-30 parts thiophene polyamide, 50-150 parts organic solvent, 10-30 parts nano-ceramic particles, 2-10 parts emulsifier, and 1-10 parts adhesive. For example, it could be 6 parts thiophene polyamide, 50 parts organic solvent, 10 parts nano-ceramic particles, 2 parts emulsifier, and 10 parts adhesive; 10 parts thiophene polyamide, 80 parts organic solvent, 15 parts nano-ceramic particles, 5 parts emulsifier, and 15 parts adhesive; 20 parts thiophene polyamide, 100 parts organic solvent, 20 parts nano-ceramic particles, 8 parts emulsifier, and 2 parts adhesive, etc.

[0089] In a preferred embodiment of the present invention, the conditions for the first mixing include: a temperature of 15~30℃, a time of 0.5~2h, and a stirring rate of 150~300rpm.

[0090] In a preferred embodiment of the present invention, the conditions for the second mixing include: a temperature of 15~30°C, a time of 1~3 hours, and a stirring rate of 150~300 rpm.

[0091] In a preferred embodiment of the present invention, adhesive A is a zinc carboxylate salt of a polyaromatic olefin composed of a first monomer, a second monomer, and zinc hydroxide. Compared with conventional adhesives, adhesive A has higher heat resistance and strength because it introduces zinc metal into its structure. The introduction of inorganic matter enhances its rigidity and hardness, and makes it more dimensionally stable.

[0092] In a preferred embodiment of the present invention, the structural formula of the first monomer is shown in formula (a):

[0093] ;

[0094] The second monomer is butadiene; adhesive A introduces carboxyl groups into its structure, which enable the carboxyl oxygen to form hydrogen bonds with the amide bonds of thiophene polyamide, thereby enhancing the bonding force; the high polarity of the carboxyl group enhances the bonding force with the base film.

[0095] The adhesive A used in this invention acts as a bridge, bonding the base film on one hand and the thiophene polyamide on the other, making the bond between the two stronger and improving the safety performance of the battery.

[0096] In a preferred embodiment of the present invention, the method for preparing adhesive A includes:

[0097] 1) In the presence of the first solvent, the first monomer is mixed with zinc hydroxide and reacted, then distilled under reduced pressure and dried to obtain the zinc carboxylate salt of the first monomer;

[0098] 2) In the presence of the second solvent, the zinc carboxylate salt of the first monomer obtained in step 1) is mixed with the second monomer, and then tetramethylethylenediamine and n-butyllithium are added to initiate polymerization;

[0099] The structural formula of the first monomer is shown in formula (a):

[0100] ;

[0101] The second monomer is butadiene.

[0102] In a preferred embodiment of the present invention, in step 1), the first solvent is a mixed solution of ethanol and water, and the mass ratio of ethanol to water is 1~2:1, preferably 2:1.

[0103] In a preferred embodiment of the present invention, in step 1), the conditions for the mixing reaction include: a temperature of 40~60℃ and a time of 1~3h, for example, it can be.

[0104] In a preferred embodiment of the present invention, in step 1), the mass ratio of the first monomer to zinc hydroxide is 1:0.2 to 0.6, for example, it can be 1:0.2, 1:0.3, 1:0.4, 1:0.5 and 1:0.6.

[0105] In a preferred embodiment of the present invention, in step 2), the second solvent is tetrahydrofuran.

[0106] In a preferred embodiment of the present invention, in step 2), the mass ratio of the zinc carboxylate salt of the first monomer to the second monomer is 1:0.2 to 0.6, for example, it can be 1:0.2, 1:0.3, 1:0.4, 1:0.5 and 1:0.6.

[0107] In a preferred embodiment of the present invention, in step 2), the mixing conditions include: under anaerobic conditions, a stirring rate of 150~300 rpm and a temperature of 40~50℃.

[0108] In a preferred embodiment of the present invention, in step 2), 5-10 mmol of tetramethylethylenediamine and 5-10 mmol of n-butyllithium are added per 100g of butadiene. Preferably, 8 mmol of tetramethylethylenediamine and 8 mmol of n-butyllithium are added per 100g of butadiene.

[0109] In a preferred embodiment of the present invention, in step 2), the polymerization conditions include: under a nitrogen atmosphere and / or an argon atmosphere, the polymerization temperature is 30~60℃ and the time is 4~8h.

[0110] In a second aspect, the present invention provides an application of a thiophene-based polyamide coating liquid in the preparation of a lithium battery separator, wherein the thiophene-based polyamide coating liquid is the thiophene-based polyamide coating liquid prepared by the preparation method described in the first aspect.

[0111] Thirdly, the present invention provides a method for preparing a lithium battery separator, the method comprising: coating a thiophene-based polyamide coating solution onto one or both sides of a base film, performing coagulation bath extraction, and drying; wherein,

[0112] The thiophene polyamide coating liquid is the thiophene polyamide coating liquid prepared by the preparation method described in the first aspect;

[0113] The coating thickness is 0.5~4μm;

[0114] The base film is a polyethylene base film or a polypropylene base film.

[0115] This invention applies thiophene-based polyamides to the field of lithium-ion battery separators. The thiophene-based lithium-ion battery coated separator prepared using a thiophene-based polyamide coating solution exhibits low thermal shrinkage, good wettability, and inherent adhesive properties, resulting in better safety compared to traditional separators. Furthermore, the thiophene-based polyamide coating solution disclosed in this invention has a simple composition, solving the problems of excessive ingredients and high costs associated with existing coated separator technologies. Simultaneously, thiophene-based polyamides are bio-based materials with widely available, sustainable, and renewable raw materials, making them environmentally friendly.

[0116] In this invention, the room temperature is 15~30℃.

[0117] The present invention will be described in detail below through examples. In the following examples, the pharmaceuticals and agents are all conventional commercially available products.

[0118] Preparation Example 1

[0119] This preparation example illustrates the preparation of adhesive A:

[0120] (1) Add 1 kg of water and 2 kg of ethanol to the reactor, add 100 g of the first monomer and 40 g of zinc hydroxide, and react at 50 °C for 2 hours; evaporate the solvent under reduced pressure (50 °C, 5 mmHg) to obtain the zinc carboxylate salt of the first monomer.

[0121] (2) 50 g of zinc carboxylate salt of the first monomer and 300 ml of tetrahydrofuran were added to the polymerization flask in sequence and stirred. 20 g of butadiene was added under anaerobic conditions and heated to 45 °C. 0.2 g of tetramethylethylenediamine (TMEDA) and 0.8 mL of n-butyllithium (2.0 mol / L, cyclohexane solution) were added to initiate polymerization. After polymerization for 5 h, polymerization was terminated with 5 ml of ethanol. The polymer solution was poured into water to precipitate solids. The solids were filtered and dried at 40 °C to obtain adhesive A.

[0122] The first monomer structure is shown in equation (a):

[0123]

[0124] Preparation Example 2

[0125] This preparation example illustrates the preparation of compounds 1-12:

[0126] Under nitrogen protection, 100 g of DMAC was added first, followed by the diamine monomer. At 5 °C, the diacyl chloride monomer was added, and the reaction was carried out for 2 hours. 100 ml of ethanol was added, and a solid was precipitated. The solid was filtered and the filter cake was dried to obtain thiophene polyamide solid, namely compound 1-12.

[0127] The types and amounts of monomers used in compounds 1-12 are shown in Table 1.

[0128] Table 1

[0129]

[0130] Example 1

[0131] 100 g of organic solvent N,N-dimethylformamide and 18 g of thiophene polyamide (compound 1) were added sequentially to the reactor and stirred for 1 hour. Then, 16 g of alumina, 2 g of adhesive A and 5 g of sodium p-benzenesulfonate were added and stirred for another 2 hours to prepare the thiophene polyamide coating solution.

[0132] Example 2

[0133] 100 g of organic solvent N,N-dimethylformamide and 18 g of thiophene polyamide (compound 2) were added sequentially to the reactor and stirred for 1 hour. Then, 16 g of alumina, 2 g of adhesive A and 5 g of sodium p-benzenesulfonate were added and stirred for another 2 hours to prepare the thiophene polyamide coating solution.

[0134] Example 3

[0135] 100 g of organic solvent N,N-dimethylformamide and 18 g of thiophene polyamide (compound 3) were added sequentially to the reactor and stirred for 1 hour. Then, 16 g of alumina, 2 g of adhesive A and 5 g of sodium p-benzenesulfonate were added and stirred for another 2 hours to prepare the thiophene polyamide coating solution.

[0136] Compound 3 is a polymer of 31.3g thiophene dicarboxylate chloride and 30g 4,4-diaminodiphenyl ether.

[0137] Example 4

[0138] 100 g of organic solvent N,N-dimethylformamide and 18 g of thiophene polyamide (compound 4) were added sequentially to the reactor and stirred for 1 hour. Then, 16 g of alumina, 2 g of adhesive A and 5 g of sodium p-benzenesulfonate were added and stirred for another 2 hours to prepare the thiophene polyamide coating solution.

[0139] Example 5

[0140] 100 g of organic solvent N,N-dimethylformamide and 18 g of thiophene polyamide (compound 5) were added sequentially to the reactor and stirred for 1 hour. Then, 16 g of alumina, 2 g of adhesive A and 5 g of sodium p-benzenesulfonate were added and stirred for another 2 hours to prepare the thiophene polyamide coating solution.

[0141] Example 6

[0142] 100 g of organic solvent N,N-dimethylformamide and 18 g of thiophene polyamide (compound 6) were added sequentially to the reactor and stirred for 1 hour. Then, 16 g of alumina, 2 g of adhesive A and 5 g of sodium p-benzenesulfonate were added and stirred for another 2 hours to prepare the thiophene polyamide coating solution.

[0143] Example 7

[0144] 100 g of organic solvent N,N-dimethylformamide and 18 g of thiophene polyamide (compound 7) were added sequentially to the reactor and stirred for 1 hour. Then, 16 g of alumina, 2 g of adhesive A and 33 g of sodium p-benzenesulfonate were added and stirred for another 2 hours to prepare the thiophene polyamide coating solution.

[0145] Example 8

[0146] 100 g of organic solvent N,N-dimethylformamide and 18 g of thiophene polyamide (compound 8) were added sequentially to the reactor and stirred for 1 hour. Then, 16 g of alumina, 5 g of sodium p-benzenesulfonate and 2 g of adhesive A were added and stirred for another 2 hours to prepare the thiophene polyamide coating solution.

[0147] Example 9

[0148] 100 g of organic solvent N,N-dimethylformamide and 18 g of thiophene polyamide (compound 9) were added sequentially to the reactor and stirred for 1 hour. Then, 16 g of alumina, 2 g of adhesive A and 5 g of sodium p-benzenesulfonate were added and stirred for another 2 hours to prepare the thiophene polyamide coating solution.

[0149] Example 10

[0150] 100 g of organic solvent N,N-dimethylformamide, 2 g of adhesive A, and 18 g of thiophene polyamide (compound 10) were added sequentially to the reactor. The mixture was stirred for 1 hour, then 16 g of alumina and 5 g of sodium p-benzenesulfonate were added, and the mixture was stirred for another 2 hours to prepare the thiophene polyamide coating solution.

[0151] Example 11

[0152] 100 g of organic solvent N,N-dimethylformamide, 18 g of thiophene polyamide (compound 11) were added to the reactor in sequence and stirred for 1 hour. Then, 16 g of alumina, 2 g of adhesive A, 4 g of sodium p-benzenesulfonate, and 1 g of copolymer vinyl acetate were added and stirred for another 2 hours to prepare the thiophene polyamide coating solution.

[0153] Example 12

[0154] 100 g of organic solvent N,N-dimethylformamide and 18 g of thiophene polyamide (compound 12) were added sequentially to the reactor and stirred for 1 hour. Then, 16 g of alumina, 2 g of adhesive A and 5 g of sodium p-benzenesulfonate were added and stirred for another 2 hours to prepare the thiophene polyamide coating solution.

[0155] Example 13

[0156] 100 g of N,N-dimethylformamide, 9 g of thiophene polyamide (compound 5), and 9 g of polyvinylidene fluoride (PVDF) were added sequentially to the reactor. The mixture was stirred for 1 hour, then 16 g of alumina, 20 g of adhesive A, and 5 g of sodium p-benzenesulfonate were added. The mixture was stirred for another 2 hours to prepare the thiophene polyamide coating solution.

[0157] Comparative Example 1

[0158] The coating liquid was prepared by implementing the method described in Example 5, except that thiophene polyamide was not added.

[0159] Comparative Example 2

[0160] The method described in Example 5 was carried out, except that "2 grams of adhesive A" was replaced with "2 grams of PVDF" to prepare the coating liquid.

[0161] Comparative Example 3

[0162] The coating liquid was prepared by implementing the method described in Example 5, except that "20 grams of adhesive A" was not added.

[0163] Application Example 1

[0164] A polyethylene base film with a thickness of 10 μm was selected. The thiophene polyamide coating solution prepared in Examples 1-13 and the coating solution prepared in Comparative Examples 1-2 were coated on both sides of the base film respectively, with a coating thickness of 1 μm. The film was then extracted in a coagulation bath and dried to obtain the lithium battery separator.

[0165] Test Example 1

[0166] The performance testing methods and standards for lithium battery separators coated with the thiophene-based polyamide coating solutions prepared in Examples 1-13 and the coating solutions prepared in Comparative Examples 1-2 are as follows:

[0167] (1) The liquid absorption rate test method refers to the standard QB / T 2303.11-2008. The electrolyte solvent is a mixture of ethylene carbonate and dimethyl carbonate with a mass ratio of 1:1.

[0168] (2) Heat shrinkage test method:

[0169] Cut the diaphragm into 10cm×10cm samples, measure its longitudinal length (MD-1) and transverse length (TD-1) before heating, place it in a vacuum oven and bake at 150℃ for 1 hour, take out the diaphragm sample, cool it to room temperature, and measure its longitudinal length (MD-2) and transverse length (TD-2) again, and calculate the heat shrinkage rate y according to the following formula.

[0170] Y(MD)=(MD1-MD2) / MD1×100%

[0171] Y(TD)=(TD1-TD2) / TD1×100%

[0172] (3) Air permeability test method: Refer to the national standard GB / T36363-2018 for testing;

[0173] (4) Peel strength method: Tested according to national standard GB / T36363-2018;

[0174] The performance test data of the lithium battery separators coated with the thiophene polyamide coating solutions prepared in Examples 1-13 and the coating solutions prepared in Comparative Examples 1-2 are shown in Table 2.

[0175] Table 2

[0176]

[0177] As shown in Table 2, the lithium battery separators coated with the thiophene polyamide coating liquid in Examples 1-13 of the present invention have significantly improved liquid absorption rate, significantly reduced thermal shrinkage rate, and improved air permeability compared with the lithium battery separators coated with the coating liquid without thiophene polyamide in Comparative Example 1. This indicates that the lithium battery separators coated with the thiophene polyamide coating liquid of the present invention have better thermal stability and wettability.

[0178] Furthermore, the lithium battery separators coated with the thiophene polyamide coating liquid in Examples 1-13 of the present invention exhibit significantly improved peel strength compared to the lithium battery separators coated with the coating liquid in Comparative Example 1 without the addition of thiophene polyamide and binder. This indicates that thiophene polyamide has adhesive properties and can play a role in bonding ceramics.

[0179] Meanwhile, the performance data of the separators in Comparative Example 2 and Example 5 show that the lithium battery separator coated with the thiophene polyamide coating liquid prepared by adhesive A in Example 5 has higher heat resistance and adhesion than the lithium battery separator coated with the thiophene polyamide coating liquid prepared by commercially available adhesive PVDF in Comparative Example 2.

[0180] Meanwhile, the performance data of the diaphragms in Comparative Example 3 and Example 5 show that the addition of adhesive A improves both the thermal stability and peel strength of the diaphragm.

[0181] Furthermore, no gelation phenomenon was observed in the polymers during the experiments of this invention; they remained in a uniform and stable solution state, indicating that the stability of the thiophene-based polyamide coating solution is superior to that of the aramid slurry.

[0182] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0183] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0184] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing a thiophene-based polyamide coating liquid, characterized in that, The preparation method includes: first mixing an organic solvent with thiophene polyamide, and then adding nano-ceramic particles, an emulsifier and an adhesive for a second mixing; The thiophene-based polyamide is composed of a diacyl chloride monomer and a diamine monomer; wherein... The diacyl chloride monomer is selected from one or more of the following: thiophene dicarboxylate chloride, comonomers composed of thiophene dicarboxylate chloride and aromatic diacyl chloride, comonomers composed of thiophene dicarboxylate chloride and heterocyclic diacyl chloride, and comonomers composed of thiophene dicarboxylate chloride and aliphatic diacyl chloride. The diamine monomer is selected from one or more of aryl diamines, aliphatic diamines, and heterocyclic diamines.

2. The preparation method according to claim 1, characterized in that, The diacyl chloride monomer is selected from one or more of the following: naphthalene dicarboxyl chloride, isophthaloyl chloride, 1,3,5-benzenetricarboxyl chloride, 2,5-furan dicarboxyl chloride, terephthaloyl chloride, piperidine dicarboxyl chloride, and pyridine dicarboxyl chloride. The diamine monomer is selected from one or more of 2-(4-aminophenyl)-5-aminobenzoxazole, 4,4'-(1,4-phenyldioxy)bisphenylamine, 2-(4-aminophenyl)-5-aminobenzimidazole, 3,4-diaminodiphenyl ether, butanediamine, pentanediamine, hexamethylenediamine, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3-diaminodiphenyl sulfone, m-phenylenediamine, 9,9-bis(4-aminophenyl)fluorene, naphthyldiamine, p-phenylenediamine, 4,4-diaminodiphenyl ether, 2,2'-bis(trifluoromethyl)diaminobiphenyl, 4,4-diaminodiphenyl sulfone, ethylenediamine, propylenediamine, nonanediamine, 4,4'-bis3-aminophenoxydiphenyl sulfone, and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane.

3. The preparation method according to claim 1, characterized in that, The general structural formula of the thiophene polyamide is shown in Formulas I-VI. ， ， ， ， ， ； Wherein, X and Y are each independently selected from one of H, alkyl, halogen atom, amino, amino-derived group, hydroxyl and hydroxy-derived group; m≥1 and is an integer, h≥1 and is an integer, n≥1 and is an integer, k≥1 and is an integer; R', R'' and R''' are each independently selected from one of the following groups: alkyl, phenyl, bridged ring group, spirocyclic group and heterocyclic group.

4. The preparation method according to claim 1, characterized in that, The organic solvent is selected from one or more of N-methylpyrrolidone, N-ethylpyrrolidone, γ-valerolactone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, and ethylene glycol dimethyl ether; and / or, The emulsifier is selected from one or more of sodium thiophene dicarboxylate, sodium succinate, sodium p-benzenesulfonate, lithium succinate, lithium p-benzenesulfonate, and sodium dodecyl sulfonate; and / or, The adhesive is selected from one or more of adhesive A, a mixture of adhesive A and PVDF, a mixture of adhesive A and copolyvinyl acetate, and a mixture of adhesive A and styrene-butadiene rubber; and / or, The nano-ceramic particles are selected from one or more of alumina, magnesium oxide, zinc oxide, aluminum hydroxide, and silicon dioxide; and / or, The nano-ceramic particles have a particle size of 300~500nm; and / or, The organic solvent, thiophene polyamide, nano-ceramic particles, emulsifier and adhesive are composed of the following weight parts: 6-30 parts thiophene polyamide, 50-150 parts organic solvent, 10-30 parts nano-ceramic particles, 2-10 parts emulsifier and 1-10 parts adhesive. And / or, The conditions for the first mixing include: a temperature of 15~30℃, a time of 0.5~2h, and a stirring rate of 150~300rpm; and / or, The conditions for the second mixing include: a temperature of 15~30℃, a time of 1~3h, and a stirring speed of 150~300rpm.

5. The preparation method according to claim 4, characterized in that, The adhesive A is a zinc carboxylate salt of a polyaromatic olefin composed of a first monomer, a second monomer, and zinc hydroxide; and / or, The structural formula of the first monomer is shown in formula (a): ； The second monomer is butadiene.

6. The preparation method according to claim 4 or 5, characterized in that, The preparation method of adhesive A includes: 1) In the presence of the first solvent, the first monomer is mixed with zinc hydroxide and reacted, then distilled under reduced pressure and dried to obtain the zinc carboxylate salt of the first monomer; 2) In the presence of the second solvent, the zinc carboxylate salt of the first monomer obtained in step 1) is mixed with the second monomer, and then tetramethylethylenediamine and n-butyllithium are added to initiate polymerization; The structural formula of the first monomer is shown in formula (a): ； The second monomer is butadiene.

7. The preparation method according to claim 6, characterized in that, In step 1), the first solvent is a mixture of ethanol and water, with a mass ratio of ethanol to water of 1~2:1; and / or, In step 1), the conditions for the mixing reaction include: a temperature of 40~60℃ and a time of 1~3h; and / or, In step 1), the mass ratio of the first monomer to zinc hydroxide is 1:0.2~0.6; and / or, In step 2), the second solvent is tetrahydrofuran; and / or, In step 2), the mass ratio of the zinc carboxylate of the first monomer to the second monomer is 1:0.2~0.6; and / or, In step 2), the mixing conditions include: an anaerobic environment, a stirring rate of 150-300 rpm, and a temperature of 40-50°C; and / or, In step 2), 5-10 mmol of tetramethylethylenediamine and 5-10 mmol of n-butyllithium are added per 100 g of butadiene; and / or, In step 2), the polymerization conditions include: under a nitrogen atmosphere and / or an argon atmosphere, a polymerization temperature of 30~60℃, and a time of 4~8h.

8. The application of a thiophene-based polyamide coating solution in the preparation of lithium battery separators, characterized in that, The thiophene polyamide coating liquid is the thiophene polyamide coating liquid prepared by the preparation method described in any one of claims 1-7.

9. A method for preparing a lithium battery separator, characterized in that, The preparation method includes: coating a thiophene-based polyamide coating solution onto one or both sides of a base film, performing coagulation bath extraction, and drying; wherein, The thiophene polyamide coating liquid is a thiophene polyamide coating liquid prepared by the preparation method according to any one of claims 1-7; The coating thickness is 0.5~4μm; The base film is a polyethylene base film or a polypropylene base film.

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