A high heat-resistant battery separator and a method for preparing the battery thereof.

Abstract

This invention discloses a high heat-resistant battery separator and a method for preparing the same battery, relating to the field of battery separator technology. The method for preparing the high heat-resistant battery separator includes the following steps: Step 1. Preparing a modified porous silica fiber membrane; Step 2. Preparing porous silica-modified polyimide; Step 3. Preparing the high heat-resistant battery separator: (1) Adding porous silica-modified polyimide and a photoinitiator to dimethylacetamide, stirring and mixing evenly to obtain a coating solution; (2) Evenly coating the coating solution onto both surfaces of the modified porous silica fiber membrane, followed by vacuum drying and ultraviolet crosslinking to obtain the high heat-resistant battery separator. The method for preparing the battery is as follows: The high heat-resistant battery separator is wound and assembled with a positive electrode active material and a negative electrode active material, and an electrolyte is injected to obtain the battery.

Description

Technical Field

[0001] This invention relates to the field of battery separator technology, specifically a high heat-resistant battery separator and a method for preparing the same battery. Background Technology

[0002] As a core technology in the new energy field, the safety and performance optimization of lithium-ion batteries have always been a key research focus. Traditional battery separators mostly use polyolefin materials (such as polyethylene PE and polypropylene PP), which have cost advantages, but poor thermal stability (heat shrinkage temperature ≤120℃). In high-temperature environments, they are prone to softening, shrinking, or even melting, leading to short circuits and thermal runaway at the contact between the positive and negative electrodes, seriously threatening battery safety. Especially under high-energy-density battery fast charging or extreme operating conditions, traditional separators are unable to meet safety requirements.

[0003] To address these issues, high-heat-resistant membrane materials have become a research hotspot. Polyimide (PI) is considered an ideal alternative material due to its excellent thermal stability (thermal decomposition temperature ≥400℃), mechanical strength, and chemical inertness. However, the traditional PI membrane preparation process is complex, and the pore structure is difficult to control, resulting in insufficient ion conductivity and affecting battery performance.

[0004] Based on this, the present invention will provide a high heat-resistant battery separator, which can be applied to lithium batteries to ensure the safety performance of lithium-ion batteries. This is of great significance for promoting the widespread application of lithium batteries in electric vehicles, energy storage systems and other fields. Summary of the Invention

[0005] The purpose of this invention is to provide a high heat-resistant battery separator and a method for preparing the battery thereof, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A method for preparing a high heat-resistant battery separator includes the following steps:

[0008] Step 1. Preparation of modified porous silica fiber membrane: (1) A porous silica fiber membrane is obtained by electrospinning and calcining a silica spinning solution containing polystyrene nanospheres; (2) The porous silica fiber membrane is modified by a vinyl silane coupling agent to obtain a modified porous silica fiber membrane.

[0009] Step 2. Preparation of porous silica-modified polyimide: (1) Add hexafluorodianhydride to a mixed solution containing 4,4'-diaminodiphenyl ether, 3,5-diaminobenzoic acid and maleic acid diamine, stir and react to obtain a polyamic acid solution; (2) Add acetic anhydride and triethylamine to the polyamic acid solution, stir and react, add methanol to precipitate, filter, wash and vacuum dry to obtain polyimide; (3) React and graft the polyimide with modified porous silica to obtain porous silica-modified polyimide;

[0010] Step 3. Preparation of high heat-resistant battery separator: (1) Add porous silica-modified polyimide and photoinitiator to dimethylacetamide, stir and mix evenly to obtain a coating liquid with a solid content of 5-15 wt%; (2) Coat the coating liquid evenly on both surfaces of the modified porous silica fiber membrane, and obtain a high heat-resistant battery separator by vacuum drying and ultraviolet crosslinking.

[0011] Further, the preparation method of the modified porous silica fiber membrane is as follows: (1) Polystyrene nanospheres are dispersed in deionized water, and then tetraethyl orthosilicate and oxalic acid are added to it at 30-50°C. After the addition is completed, the hydrolysis reaction is continued for 6-12 hours to obtain silica spinning solution; (2) The silica spinning solution is electrospun to obtain silica fiber membrane; (3) The silica fiber membrane is placed in a muffle furnace and calcined to obtain porous silica fiber membrane; (4) Vinyl silane coupling agent, deionized water and anhydrous ethanol are added to the reaction vessel, and acetic acid is added to adjust the pH of the solution to 4-6. The mixture is stirred and mixed for 10-30 minutes to obtain vinyl silane hydrolysate; (5) The porous silica fiber membrane is immersed in vinyl silane hydrolysate for 30-60 minutes, taken out and vacuum dried to obtain modified porous silica fiber membrane.

[0012] Furthermore, the mass ratio of the polystyrene nanospheres, tetraethyl orthosilicate, oxalic acid, and deionized water is (1-3):6:(0.02-0.06):50.

[0013] Furthermore, the polystyrene nanospheres have a particle size of 20–50 nm.

[0014] Furthermore, the parameters for electrospinning are: spinning voltage of 15-25kV, receiving distance of 15-20cm, and injection speed of 0.5-1.5mL / h.

[0015] Furthermore, the thickness of the silica fiber membrane is 4–10 μm.

[0016] Furthermore, the calcination parameters are as follows: heating to 450-550℃ at a heating rate of 2-10℃ / min and calcining for 3-9 hours.

[0017] Furthermore, the mass ratio of the vinyl silane coupling agent, deionized water, and anhydrous ethanol is 1:1:4.

[0018] Furthermore, the vinyl silane coupling agent includes, but is not limited to, any one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(2-methoxyethoxy)silane, vinyltriisopropoxysilane, and vinyldimethylethoxysilane.

[0019] Further, the preparation method of the porous silica-modified polyimide is as follows: (1) 4,4'-diaminodiphenyl ether, 3,5-diaminobenzoic acid, and maleic acid diamine are added to dimethylacetamide, stirred and mixed evenly, and then hexafluorodianhydride is added to the solution under nitrogen protection, and the mixture is stirred and reacted at 10-20°C for 12-36 h to obtain a polyamic acid solution; (2) Acetic anhydride and triethylamine are added to the polyamic acid solution under nitrogen protection, and the mixture is stirred and reacted for 12-24 h; then, acetic anhydride and triethylamine are added to the reaction system. Add sufficient methanol to precipitate the precipitate. After filtration and washing, vacuum dry at 250-300℃ for 12-24h to obtain polyimide; (3) Under nitrogen protection, add polyimide, dicyclohexylcarbodiimide and 4-dimethylaminopyridine to dimethylacetamide, stir and mix evenly, then add modified porous silica to the solution, stir and react for 12-36h, then add sufficient methanol to the reaction system to precipitate the precipitate, after filtration, washing and vacuum drying to obtain porous silica modified polyimide.

[0020] Furthermore, the raw materials required for preparing the porous silica-modified polyimide include the following components by weight: 9.2-9.6 parts of 4,4'-diaminodiphenyl ether, 7-7.3 parts of 3,5-diaminobenzoic acid, 0.46-0.92 parts of maleic diamine, 44.4-46.6 parts of hexafluorodianhydride, 40-45 parts of acetic anhydride, 10-12 parts of triethylamine, 9-10 parts of dicyclohexylcarbodiimide, 4.5-5 parts of 4-dimethylaminopyridine, 6-8 parts of modified porous silica, and 300 parts of dimethylacetamide.

[0021] Further, the preparation method of the modified porous silica is as follows: (1) add amino silane coupling agent, deionized water and anhydrous ethanol into the reaction vessel, and add acetic acid to adjust the pH of the solution to 4-6, stir and mix for 10-30 min to obtain amino silane hydrolysate; (2) add porous silica into a stirrer, stir at a rate of 100-200 r / min, and spray amino silane hydrolysate evenly into it at the same time. After spraying, continue to stir and mix for 1-3 h, and dry to obtain modified porous silica.

[0022] Furthermore, the mass ratio of the amino-based silane coupling agent, deionized water, and anhydrous ethanol is 1:1:4.

[0023] Furthermore, the amount of the amino-based silane coupling agent added is 1 to 5% of the mass of the porous silica.

[0024] Furthermore, the amino-based silane coupling agent includes, but is not limited to, any one of 3-aminopropyltrimethoxysilane, bis[(3-trimethoxysilyl)propyl]amine, 3-aminopropyltriethoxysilane, bis[(3-triethoxysilyl)propyl]amine, 3-aminopropylmethyldimethoxysilane, and 3-aminopropylmethyldiethoxysilane.

[0025] Furthermore, the amount of photoinitiator added is 1 to 3% of the mass of the porous silica-modified polyimide.

[0026] Furthermore, the parameters for the ultraviolet crosslinking are: ultraviolet wavelength of 300-400 nm.

[0027] Furthermore, the thickness of the high heat-resistant battery separator is 16–30 μm.

[0028] A method for preparing a battery specifically involves: assembling a high heat-resistant battery separator with positive electrode active materials and negative electrode active materials by winding them together, and then injecting an electrolyte to obtain the battery.

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

[0030] 1. This invention uses polystyrene nanospheres as templates and combines electrospinning and calcination processes to prepare porous silica fiber membranes. These porous silica fiber membranes, as the membrane substrate, can impart excellent mechanical strength and high-temperature stability to the membrane, thereby improving the safety performance of the batteries prepared from them.

[0031] 2. In this invention, 4,4'-diaminodiphenyl ether, 3,5-diaminobenzoic acid, maleic diamine, and hexafluorodianhydride are first subjected to a polycondensation reaction (to obtain polyamic acid with carboxyl groups and unsaturated bonds). Then, acetic anhydride and triethylamine are added for catalytic dehydration. Next, the mixture is vacuum dried at 250-300°C (thermal imidization) to obtain polyimide. Finally, the polyimide is amidated and grafted with modified porous silica to obtain porous silica-modified polyimide. Firstly, polyimide itself has excellent heat resistance, and after further grafting with porous silica, its high-temperature stability is further enhanced.

[0032] 3. Since the porous silica-modified polyimide contains unsaturated bonds, this invention further uses a vinyl silane coupling agent to modify the porous silica fiber membrane. Then, the porous silica-modified polyimide is formulated into a coating solution and coated onto the modified porous silica fiber membrane. After ultraviolet crosslinking, the two can form a stable three-dimensional crosslinked network, making the porous silica fiber membrane and the porous silica-modified polyimide more tightly bonded, greatly enhancing the structural stability of the membrane and preventing it from delaminating due to extreme reasons.

[0033] 4. Due to the synergistic effect of porous silica fiber membrane and porous silica-modified polyimide, the prepared high heat-resistant battery separator has excellent heat resistance, mechanical strength and structural stability.

[0034] 5. The high heat-resistant battery separator prepared in this invention has a high porosity, which is beneficial for electrolyte wetting. At the same time, its pore size is small, which can inhibit dendrite penetration and greatly ensure the ion conduction efficiency and safety performance of the battery. Detailed Implementation

[0035] 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.

[0036] It should be noted that the following quantities are by weight, and there are no special restrictions on the suppliers of all raw materials involved in this invention. Exemplary examples include:

[0037] In the following embodiments,

[0038] The polystyrene nanospheres have a particle size of 30 nm, model number PS01003, and were purchased from Ruige Biotechnology Co., Ltd.

[0039] Tetraethyl orthosilicate (98% purity), vinyltrimethoxysilane (99.5% purity), 4,4'-diaminodiphenyl ether (99.5% purity), 3,5-diaminobenzoic acid (99.5% purity), diamine maleate (98% purity), hexafluorodianhydride (98% purity), 3-aminopropyltrimethoxysilane (99% purity), lithium iron phosphate (97% purity, particle size ≤ 5 μm), and graphite (99.8% purity) were all purchased from Maclean's Reagent Co., Ltd.

[0040] Porous silica with an average particle size of 2 μm and a pore size of 2 nm, and photoinitiator Irgacure 2959, were both purchased from Merck.

[0041] The PP diaphragm, model Celgard 2500, with a thickness of 25μm, was purchased from Shenzhen Kejing Zhida Technology Co., Ltd.

[0042] LB-266 electrolyte, batch number: E843.250.032, was purchased from Zhengzhou Aikem Chemical Co., Ltd.; all others were purchased commercially.

[0043] In the following examples, each serving is 10g.

[0044] Example 1: A high heat-resistant battery separator and its preparation method:

[0045] Step 1. Preparation of modified porous silica fiber membrane: (1) Disperse polystyrene nanospheres in deionized water, and then add tetraethyl orthosilicate and oxalic acid at 40°C with stirring. After the addition is complete, continue stirring for 9 hours to hydrolyze the mixture and obtain silica spinning solution (the mass ratio of polystyrene nanospheres, tetraethyl orthosilicate, oxalic acid and deionized water is 2:6:0.04:50); (2) Electrospin the silica spinning solution to obtain a 6μm thick silica fiber membrane (the electrospinning parameters are: spinning voltage of 20kV, receiving distance of 17cm, and injection speed of 1mL / h); (3) Place the silica fiber membrane in (3) The porous silica fiber membrane was calcined in a muffle furnace to obtain a porous silica fiber membrane (calcination parameters: heating to 500℃ at a heating rate of 5℃ / min for 6h); (4) Vinyltrimethoxysilane, deionized water, and anhydrous ethanol were added to the reaction vessel, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred for 20min to obtain a vinyl silane hydrolysate (the mass ratio of vinyltrimethoxysilane, deionized water, and anhydrous ethanol was 1:1:4); (5) The porous silica fiber membrane was immersed in the vinyl silane hydrolysate for 45min, taken out, and vacuum dried at 70℃ for 6h to obtain a modified porous silica fiber membrane.

[0046] Step 2.

[0047] 1. Preparation of modified porous silica: (1) 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol were added to the reaction vessel, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred for 20 min to obtain an amino silane hydrolysate (the mass ratio of 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol was 1:1:4; the amount of 3-aminopropyltrimethoxysilane added was 3% of the mass of porous silica); (2) Porous silica was added to a stirrer and stirred at a rate of 150 r / min. At the same time, the amino silane hydrolysate was sprayed evenly into it. After spraying, the mixture was stirred for 2 h. After drying, modified porous silica was obtained.

[0048] 2. Preparation of porous silica-modified polyimide: (1) 9.4 parts (0.47 mol) of 4,4'-diaminodiphenyl ether, 7.15 parts (0.47 mol) of 3,5-diaminobenzoic acid, and 0.68 parts (0.06 mol) of maleic acid diamine were added to 200 parts of dimethylacetamide and stirred until homogeneous. Then, under nitrogen protection, 45 parts (1.01 mol) of hexafluorodianhydride were added to the solution and stirred at 15°C for 24 h to obtain a polyamic acid solution; (2) Under nitrogen protection, 43 parts of acetic anhydride and 11 parts of triethylamine were added to the polyamic acid solution and stirred. The reaction was carried out for 18 hours; then, sufficient methanol was added to the reaction system to precipitate the precipitate. After filtration and washing, the precipitate was dried under vacuum at 280°C for 18 hours to obtain polyimide; (3) Under nitrogen protection, the polyimide obtained in (2), 9.5 parts of dicyclohexylcarbodiimide, and 4.75 parts of 4-dimethylaminopyridine were added to 100 parts of dimethylacetamide and stirred and mixed evenly. Then, 7 parts of modified porous silica were added to the solution and stirred for 24 hours. Then, sufficient methanol was added to the reaction system to precipitate the precipitate. After filtration and washing, the precipitate was dried under vacuum at 140°C for 6 hours to obtain porous silica-modified polyimide;

[0049] Step 3. Preparation of high heat-resistant battery separator: (1) Add porous silica-modified polyimide and Irgacure 2959 to dimethylacetamide, stir and mix evenly to obtain a coating solution with a solid content of 10wt%; (2) Coat the coating solution evenly on both surfaces of the modified porous silica fiber membrane, vacuum dry at 140℃ for 6h, and then perform ultraviolet crosslinking under ultraviolet light at a wavelength of 365nm to obtain a high heat-resistant battery separator with a thickness of 25μm.

[0050] Example 2: A high heat-resistant battery separator and its preparation method:

[0051] Step 1. Preparation of modified porous silica fiber membrane: (1) Disperse polystyrene nanospheres in deionized water, and then add tetraethyl orthosilicate and oxalic acid at 40°C with stirring. After the addition is complete, continue stirring for 9 hours to hydrolyze the mixture and obtain silica spinning solution (the mass ratio of polystyrene nanospheres, tetraethyl orthosilicate, oxalic acid and deionized water is 1:6:0.02:50); (2) Electrospin the silica spinning solution to obtain a 6μm thick silica fiber membrane (the electrospinning parameters are: spinning voltage of 20kV, receiving distance of 17cm, and injection speed of 1mL / h); (3) Place the silica fiber membrane in (3) The porous silica fiber membrane was calcined in a muffle furnace to obtain a porous silica fiber membrane (calcination parameters: heating to 500℃ at a heating rate of 5℃ / min for 6h); (4) Vinyltrimethoxysilane, deionized water, and anhydrous ethanol were added to the reaction vessel, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred for 20min to obtain a vinyl silane hydrolysate (the mass ratio of vinyltrimethoxysilane, deionized water, and anhydrous ethanol was 1:1:4); (5) The porous silica fiber membrane was immersed in the vinyl silane hydrolysate for 45min, taken out, and vacuum dried at 70℃ for 6h to obtain a modified porous silica fiber membrane.

[0052] Step 2.

[0053] 1. Preparation of modified porous silica: (1) 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol were added to the reaction vessel, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred for 20 min to obtain an amino silane hydrolysate (the mass ratio of 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol was 1:1:4; the amount of 3-aminopropyltrimethoxysilane added was 3% of the mass of porous silica); (2) Porous silica was added to a stirrer and stirred at a rate of 150 r / min. At the same time, the amino silane hydrolysate was sprayed evenly into it. After spraying, the mixture was stirred for 2 h. After drying, modified porous silica was obtained.

[0054] 2. Preparation of porous silica-modified polyimide: (1) 9.4 parts (0.47 mol) of 4,4'-diaminodiphenyl ether, 7.15 parts (0.47 mol) of 3,5-diaminobenzoic acid, and 0.68 parts (0.06 mol) of maleic acid diamine were added to 200 parts of dimethylacetamide and stirred until homogeneous. Then, under nitrogen protection, 45 parts (1.01 mol) of hexafluorodianhydride were added to the solution and stirred at 15°C for 24 h to obtain a polyamic acid solution; (2) Under nitrogen protection, 43 parts of acetic anhydride and 11 parts of triethylamine were added to the polyamic acid solution and stirred. The reaction was carried out for 18 hours; then, sufficient methanol was added to the reaction system to precipitate the precipitate. After filtration and washing, the precipitate was dried under vacuum at 280°C for 18 hours to obtain polyimide; (3) Under nitrogen protection, the polyimide obtained in (2), 9.5 parts of dicyclohexylcarbodiimide, and 4.75 parts of 4-dimethylaminopyridine were added to 100 parts of dimethylacetamide and stirred and mixed evenly. Then, 7 parts of modified porous silica were added to the solution and stirred for 24 hours. Then, sufficient methanol was added to the reaction system to precipitate the precipitate. After filtration and washing, the precipitate was dried under vacuum at 140°C for 6 hours to obtain porous silica-modified polyimide;

[0055] Step 3. Preparation of high heat-resistant battery separator: (1) Add porous silica-modified polyimide and Irgacure 2959 to dimethylacetamide, stir and mix evenly to obtain a coating solution with a solid content of 10wt%; (2) Coat the coating solution evenly on both surfaces of the modified porous silica fiber membrane, vacuum dry at 140℃ for 6h, and then perform ultraviolet crosslinking under ultraviolet light at a wavelength of 365nm to obtain a high heat-resistant battery separator with a thickness of 25μm.

[0056] Example 3: A high heat-resistant battery separator and its preparation method:

[0057] Step 1. Preparation of modified porous silica fiber membrane: (1) Disperse polystyrene nanospheres in deionized water, and then add tetraethyl orthosilicate and oxalic acid at 40°C with stirring. After the addition is complete, continue stirring and hydrolysis reaction for 9 hours to obtain silica spinning solution (the mass ratio of polystyrene nanospheres, tetraethyl orthosilicate, oxalic acid and deionized water is 3:6:0.06:50); (2) Electrospin the silica spinning solution to obtain a 6μm thick silica fiber membrane (the parameters of electrospinning are: spinning voltage of 20kV, receiving distance of 17cm, and injection speed of 1mL / h); (3) Place the silica fiber membrane in (3) The porous silica fiber membrane was calcined in a muffle furnace to obtain a porous silica fiber membrane (calcination parameters: heating to 500℃ at a heating rate of 5℃ / min for 6h); (4) Vinyltrimethoxysilane, deionized water, and anhydrous ethanol were added to the reaction vessel, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred for 20min to obtain a vinyl silane hydrolysate (the mass ratio of vinyltrimethoxysilane, deionized water, and anhydrous ethanol was 1:1:4); (5) The porous silica fiber membrane was immersed in the vinyl silane hydrolysate for 45min, taken out, and vacuum dried at 70℃ for 6h to obtain a modified porous silica fiber membrane.

[0058] Step 2.

[0059] 1. Preparation of modified porous silica: (1) 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol were added to the reaction vessel, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred for 20 min to obtain an amino silane hydrolysate (the mass ratio of 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol was 1:1:4; the amount of 3-aminopropyltrimethoxysilane added was 3% of the mass of porous silica); (2) Porous silica was added to a stirrer and stirred at a rate of 150 r / min. At the same time, the amino silane hydrolysate was sprayed evenly into it. After spraying, the mixture was stirred for 2 h. After drying, modified porous silica was obtained.

[0060] 2. Preparation of porous silica-modified polyimide: (1) 9.4 parts (0.47 mol) of 4,4'-diaminodiphenyl ether, 7.15 parts (0.47 mol) of 3,5-diaminobenzoic acid, and 0.68 parts (0.06 mol) of maleic acid diamine were added to 200 parts of dimethylacetamide and stirred until homogeneous. Then, under nitrogen protection, 45 parts (1.01 mol) of hexafluorodianhydride were added to the solution and stirred at 15°C for 24 h to obtain a polyamic acid solution; (2) Under nitrogen protection, 43 parts of acetic anhydride and 11 parts of triethylamine were added to the polyamic acid solution and stirred. The reaction was carried out for 18 hours; then, sufficient methanol was added to the reaction system to precipitate the precipitate. After filtration and washing, the precipitate was dried under vacuum at 280°C for 18 hours to obtain polyimide; (3) Under nitrogen protection, the polyimide obtained in (2), 9.5 parts of dicyclohexylcarbodiimide, and 4.75 parts of 4-dimethylaminopyridine were added to 100 parts of dimethylacetamide and stirred and mixed evenly. Then, 7 parts of modified porous silica were added to the solution and stirred for 24 hours. Then, sufficient methanol was added to the reaction system to precipitate the precipitate. After filtration and washing, the precipitate was dried under vacuum at 140°C for 6 hours to obtain porous silica-modified polyimide;

[0061] Step 3. Preparation of high heat-resistant battery separator: (1) Add porous silica-modified polyimide and Irgacure 2959 to dimethylacetamide, stir and mix evenly to obtain a coating solution with a solid content of 10wt%; (2) Coat the coating solution evenly on both surfaces of the modified porous silica fiber membrane, vacuum dry at 140℃ for 6h, and then perform ultraviolet crosslinking under ultraviolet light at a wavelength of 365nm to obtain a high heat-resistant battery separator with a thickness of 25μm.

[0062] Based on Example 1, Examples 4 and 5 are configured as follows:

[0063] Example 4: A high heat-resistant battery separator and its preparation method:

[0064] Step 1. Preparation of modified porous silica fiber membrane: (1) Disperse polystyrene nanospheres in deionized water, and then add tetraethyl orthosilicate and oxalic acid at 40°C with stirring. After the addition is complete, continue stirring for 9 hours to hydrolyze the mixture and obtain silica spinning solution (the mass ratio of polystyrene nanospheres, tetraethyl orthosilicate, oxalic acid and deionized water is 2:6:0.04:50); (2) Electrospin the silica spinning solution to obtain a 6μm thick silica fiber membrane (the electrospinning parameters are: spinning voltage of 20kV, receiving distance of 17cm, and injection speed of 1mL / h); (3) Place the silica fiber membrane in (3) The porous silica fiber membrane was calcined in a muffle furnace to obtain a porous silica fiber membrane (calcination parameters: heating to 500℃ at a heating rate of 5℃ / min for 6h); (4) Vinyltrimethoxysilane, deionized water, and anhydrous ethanol were added to the reaction vessel, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred for 20min to obtain a vinyl silane hydrolysate (the mass ratio of vinyltrimethoxysilane, deionized water, and anhydrous ethanol was 1:1:4); (5) The porous silica fiber membrane was immersed in the vinyl silane hydrolysate for 45min, taken out, and vacuum dried at 70℃ for 6h to obtain a modified porous silica fiber membrane.

[0065] Step 2.

[0066] 1. Preparation of modified porous silica: (1) 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol were added to the reaction vessel, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred for 20 min to obtain an amino silane hydrolysate (the mass ratio of 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol was 1:1:4; the amount of 3-aminopropyltrimethoxysilane added was 3% of the mass of porous silica); (2) Porous silica was added to a stirrer and stirred at a rate of 150 r / min. At the same time, the amino silane hydrolysate was sprayed evenly into it. After spraying, the mixture was stirred for 2 h. After drying, modified porous silica was obtained.

[0067] 2. Preparation of porous silica-modified polyimide: (1) 9.2 parts (0.46 mol) of 4,4'-diaminodiphenyl ether, 7 parts (0.46 mol) of 3,5-diaminobenzoic acid, and 0.92 parts (0.08 mol) of maleic acid diamine were added to 200 parts of dimethylacetamide and stirred until homogeneous. Then, under nitrogen protection, 45 parts (1.01 mol) of hexafluorodianhydride were added to the solution and stirred at 15°C for 24 h to obtain a polyamic acid solution; (2) Under nitrogen protection, 43 parts of acetic anhydride and 11 parts of triethylamine were added to the polyamic acid solution and stirred until homogeneous. 18h; then add sufficient methanol to the reaction system to precipitate the precipitate, filter and wash, and vacuum dry at 250℃ for 12h to obtain polyimide; (3) under nitrogen protection, add the polyimide obtained in (2), 9.5 parts of dicyclohexylcarbodiimide and 4.75 parts of 4-dimethylaminopyridine to 100 parts of dimethylacetamide, stir and mix evenly, then add 6 parts of modified porous silica to the solution, stir and react for 12h, then add sufficient methanol to the reaction system to precipitate the precipitate, filter and wash, and vacuum dry at 140℃ for 6h to obtain porous silica modified polyimide;

[0068] Step 3. Preparation of high heat-resistant battery separator: (1) Add porous silica-modified polyimide and Irgacure 2959 to dimethylacetamide, stir and mix evenly to obtain a coating solution with a solid content of 10wt%; (2) Coat the coating solution evenly on both surfaces of the modified porous silica fiber membrane, vacuum dry at 140℃ for 6h, and then perform ultraviolet crosslinking under ultraviolet light at a wavelength of 365nm to obtain a high heat-resistant battery separator with a thickness of 25μm.

[0069] Example 5: A high heat-resistant battery separator and its preparation method:

[0070] Step 1. Preparation of modified porous silica fiber membrane: (1) Disperse polystyrene nanospheres in deionized water, and then add tetraethyl orthosilicate and oxalic acid at 40°C with stirring. After the addition is complete, continue stirring for 9 hours to hydrolyze the mixture and obtain silica spinning solution (the mass ratio of polystyrene nanospheres, tetraethyl orthosilicate, oxalic acid and deionized water is 2:6:0.04:50); (2) Electrospin the silica spinning solution to obtain a 6μm thick silica fiber membrane (the electrospinning parameters are: spinning voltage of 20kV, receiving distance of 17cm, and injection speed of 1mL / h); (3) Place the silica fiber membrane in (3) The porous silica fiber membrane was calcined in a muffle furnace to obtain a porous silica fiber membrane (calcination parameters: heating to 500℃ at a heating rate of 5℃ / min for 6h); (4) Vinyltrimethoxysilane, deionized water, and anhydrous ethanol were added to the reaction vessel, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred for 20min to obtain a vinyl silane hydrolysate (the mass ratio of vinyltrimethoxysilane, deionized water, and anhydrous ethanol was 1:1:4); (5) The porous silica fiber membrane was immersed in the vinyl silane hydrolysate for 45min, taken out, and vacuum dried at 70℃ for 6h to obtain a modified porous silica fiber membrane.

[0071] Step 2.

[0072] 1. Preparation of modified porous silica: (1) 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol were added to the reaction vessel, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred for 20 min to obtain an amino silane hydrolysate (the mass ratio of 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol was 1:1:4; the amount of 3-aminopropyltrimethoxysilane added was 3% of the mass of porous silica); (2) Porous silica was added to a stirrer and stirred at a rate of 150 r / min. At the same time, the amino silane hydrolysate was sprayed evenly into it. After spraying, the mixture was stirred for 2 h. After drying, modified porous silica was obtained.

[0073] 2. Preparation of porous silica-modified polyimide: (1) 9.6 parts (0.48 mol) of 4,4'-diaminodiphenyl ether, 7.3 parts (0.48 mol) of 3,5-diaminobenzoic acid, and 0.46 parts (0.04 mol) of maleic acid diamine were added to 200 parts of dimethylacetamide and stirred until homogeneous. Then, under nitrogen protection, 45 parts (1.01 mol) of hexafluorodianhydride were added to the solution and stirred at 15°C for 24 h to obtain a polyamic acid solution; (2) Under nitrogen protection, 43 parts of acetic anhydride and 11 parts of triethylamine were added to the polyamic acid solution and stirred until homogeneous. (2) After 18 hours, add sufficient methanol to the reaction system to precipitate the precipitate. After filtration and washing, vacuum dry at 300°C for 24 hours to obtain polyimide. (3) Under nitrogen protection, add the polyimide obtained in (2), 9.5 parts of dicyclohexylcarbodiimide, and 4.75 parts of 4-dimethylaminopyridine to 100 parts of dimethylacetamide. Stir and mix evenly. Then add 8 parts of modified porous silica to the solution and stir for 36 hours. Next, add sufficient methanol to the reaction system to precipitate the precipitate. After filtration and washing, vacuum dry at 140°C for 6 hours to obtain porous silica-modified polyimide.

[0074] Step 3. Preparation of high heat-resistant battery separator: (1) Add porous silica-modified polyimide and Irgacure 2959 to dimethylacetamide, stir and mix evenly to obtain a coating solution with a solid content of 10wt%; (2) Coat the coating solution evenly on both surfaces of the modified porous silica fiber membrane, vacuum dry at 140℃ for 6h, and then perform ultraviolet crosslinking under ultraviolet light at a wavelength of 365nm to obtain a high heat-resistant battery separator with a thickness of 25μm.

[0075] The following is a control experiment based on Example 1, with comparative examples 1 to 4, as detailed below:

[0076] Comparative Example 1: Comparative Example 1 is based on Example 1, with the following adjustment: polystyrene nanospheres are not added to the silica spinning solution, while other processes remain unchanged. Specifically:

[0077] A high heat-resistant battery separator and a method for preparing the battery thereon:

[0078] Step 1. Preparation of modified silica fiber membrane: (1) At 40°C, tetraethyl orthosilicate and oxalic acid were added to deionized water by stirring. After the addition was completed, the hydrolysis reaction was continued for 9 hours to obtain silica spinning solution (the mass ratio of tetraethyl orthosilicate, oxalic acid and deionized water was 6:0.04:50); (2) The silica spinning solution was electrospun to obtain a silica fiber membrane with a thickness of 6 μm (the parameters of electrospinning were: spinning voltage of 20 kV, receiving distance of 17 cm, and injection rate of 1000 kV). (3) Add vinyltrimethoxysilane, deionized water, and anhydrous ethanol to the reaction vessel, and add acetic acid to adjust the pH of the solution to 5. Stir and mix for 20 min to obtain a vinyl silane hydrolysate (the mass ratio of vinyltrimethoxysilane, deionized water, and anhydrous ethanol is 1:1:4); (5) Soak the silica fiber membrane in the vinyl silane hydrolysate for 45 min, take it out, and vacuum dry it at 70°C for 6 h to obtain a modified silica fiber membrane.

[0079] Step 2.

[0080] 1. Preparation of modified porous silica: (1) 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol were added to the reaction vessel, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred for 20 min to obtain an amino silane hydrolysate (the mass ratio of 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol was 1:1:4; the amount of 3-aminopropyltrimethoxysilane added was 3% of the mass of porous silica); (2) Porous silica was added to a stirrer and stirred at a rate of 150 r / min. At the same time, the amino silane hydrolysate was sprayed evenly into it. After spraying, the mixture was stirred for 2 h. After drying, modified porous silica was obtained.

[0081] 2. Preparation of porous silica-modified polyimide: (1) 9.4 parts (0.47 mol) of 4,4'-diaminodiphenyl ether, 7.15 parts (0.47 mol) of 3,5-diaminobenzoic acid, and 0.68 parts (0.06 mol) of maleic acid diamine were added to 200 parts of dimethylacetamide and stirred until homogeneous. Then, under nitrogen protection, 45 parts (1.01 mol) of hexafluorodianhydride were added to the solution and stirred at 15°C for 24 h to obtain a polyamic acid solution; (2) Under nitrogen protection, 43 parts of acetic anhydride and 11 parts of triethylamine were added to the polyamic acid solution and stirred. The reaction was carried out for 18 hours; then, sufficient methanol was added to the reaction system to precipitate the precipitate. After filtration and washing, the precipitate was dried under vacuum at 280°C for 18 hours to obtain polyimide; (3) Under nitrogen protection, the polyimide obtained in (2), 9.5 parts of dicyclohexylcarbodiimide, and 4.75 parts of 4-dimethylaminopyridine were added to 100 parts of dimethylacetamide and stirred and mixed evenly. Then, 7 parts of modified porous silica were added to the solution and stirred for 24 hours. Then, sufficient methanol was added to the reaction system to precipitate the precipitate. After filtration and washing, the precipitate was dried under vacuum at 140°C for 6 hours to obtain porous silica-modified polyimide;

[0082] Step 3. Preparation of high heat-resistant battery separator: (1) Add porous silica-modified polyimide and Irgacure 2959 to dimethylacetamide, stir and mix evenly to obtain a coating solution with a solid content of 10wt%; (2) Coat the coating solution evenly on both surfaces of the modified silica fiber membrane, vacuum dry at 140℃ for 6h, and then perform ultraviolet crosslinking under ultraviolet light at a wavelength of 365nm to obtain a high heat-resistant battery separator with a thickness of 25μm.

[0083] Comparative Example 2: Comparative Example 2 is based on Example 1, with the following adjustment: no modification treatment is applied to the porous silica fiber membrane, while other processes remain unchanged. Specifically:

[0084] A high heat-resistant battery separator and a method for preparing the battery thereon:

[0085] Step 1. Preparation of modified porous silica fiber membrane: (1) Disperse polystyrene nanospheres in deionized water, and then add tetraethyl orthosilicate and oxalic acid at 40°C. After the addition is complete, continue stirring and hydrolyzing for 9 hours to obtain silica spinning solution (the mass ratio of polystyrene nanospheres, tetraethyl orthosilicate, oxalic acid and deionized water is 2:6:0.04:50); (2) Electrospin the silica spinning solution to obtain a 6μm thick silica fiber membrane (the parameters of electrospinning are: spinning voltage of 20kV, receiving distance of 17cm, and injection speed of 1mL / h); (3) Place the silica fiber membrane in a muffle furnace and calcine it to obtain a porous silica fiber membrane (the parameters of calcination are: heating to 500°C at a heating rate of 5°C / min for 6 hours).

[0086] Step 2.

[0087] 1. Preparation of modified porous silica: (1) 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol were added to the reaction vessel, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred for 20 min to obtain an amino silane hydrolysate (the mass ratio of 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol was 1:1:4; the amount of 3-aminopropyltrimethoxysilane added was 3% of the mass of porous silica); (2) Porous silica was added to a stirrer and stirred at a rate of 150 r / min. At the same time, the amino silane hydrolysate was sprayed evenly into it. After spraying, the mixture was stirred for 2 h. After drying, modified porous silica was obtained.

[0088] 2. Preparation of porous silica-modified polyimide: (1) 9.4 parts (0.47 mol) of 4,4'-diaminodiphenyl ether, 7.15 parts (0.47 mol) of 3,5-diaminobenzoic acid, and 0.68 parts (0.06 mol) of maleic acid diamine were added to 200 parts of dimethylacetamide and stirred until homogeneous. Then, under nitrogen protection, 45 parts (1.01 mol) of hexafluorodianhydride were added to the solution and stirred at 15°C for 24 h to obtain a polyamic acid solution; (2) Under nitrogen protection, 43 parts of acetic anhydride and 11 parts of triethylamine were added to the polyamic acid solution and stirred. The reaction was carried out for 18 hours; then, sufficient methanol was added to the reaction system to precipitate the precipitate. After filtration and washing, the precipitate was dried under vacuum at 280°C for 18 hours to obtain polyimide; (3) Under nitrogen protection, the polyimide obtained in (2), 9.5 parts of dicyclohexylcarbodiimide, and 4.75 parts of 4-dimethylaminopyridine were added to 100 parts of dimethylacetamide and stirred and mixed evenly. Then, 7 parts of modified porous silica were added to the solution and stirred for 24 hours. Then, sufficient methanol was added to the reaction system to precipitate the precipitate. After filtration and washing, the precipitate was dried under vacuum at 140°C for 6 hours to obtain porous silica-modified polyimide;

[0089] Step 3. Preparation of high heat-resistant battery separator: (1) Add porous silica-modified polyimide and Irgacure 2959 to dimethylacetamide, stir and mix evenly to obtain a coating solution with a solid content of 10wt%; (2) Coat the coating solution evenly on both surfaces of the porous silica fiber membrane, vacuum dry at 140℃ for 6h, and then perform ultraviolet crosslinking under ultraviolet light at a wavelength of 365nm to obtain a high heat-resistant battery separator with a thickness of 25μm.

[0090] Comparative Example 3: Comparative Example 3 is based on Example 1, with the following adjustment: no modified porous silica is added to modify the polyimide, while other processes remain unchanged. Specifically:

[0091] A high heat-resistant battery separator and a method for preparing the battery thereon:

[0092] Step 1. Preparation of modified porous silica fiber membrane: (1) Disperse polystyrene nanospheres in deionized water, and then add tetraethyl orthosilicate and oxalic acid at 40°C with stirring. After the addition is complete, continue stirring and hydrolysis reaction for 9 hours to obtain silica spinning solution (the mass ratio of polystyrene nanospheres, tetraethyl orthosilicate, oxalic acid and deionized water is 2:6:0.04:50); (2) Electrospin the silica spinning solution to obtain a 6μm thick silica fiber membrane (the electrospinning parameters are: spinning voltage of 20kV, receiving distance of 17cm, and injection speed of 1mL / h); (3) Filter the silica fiber membrane (3) Place it in a muffle furnace and calcine it to obtain a porous silica fiber membrane (calcination parameters are: heating to 500℃ at a heating rate of 5℃ / min and calcining for 6h); (4) Add vinyltrimethoxysilane, deionized water and anhydrous ethanol to the reaction vessel, and add acetic acid to adjust the pH of the solution to 5. Stir and mix for 20min to obtain a vinyl silane hydrolysate (the mass ratio of vinyltrimethoxysilane, deionized water and anhydrous ethanol is 1:1:4); (5) Soak the porous silica fiber membrane in the vinyl silane hydrolysate for 45min, take it out, and vacuum dry it at 70℃ for 6h to obtain a modified porous silica fiber membrane;

[0093] Step 2. Preparation of polyimide: (1) 9.4 parts (0.47 mol) of 4,4'-diaminodiphenyl ether, 7.15 parts (0.47 mol) of 3,5-diaminobenzoic acid, and 0.68 parts (0.06 mol) of maleic acid diamine were added to 200 parts of dimethylacetamide and stirred until homogeneous. Then, under nitrogen protection, 45 parts (1.01 mol) of hexafluorodianhydride were added to the solution and stirred at 15°C for 24 h to obtain a polyamic acid solution; (2) Under nitrogen protection, 43 parts of acetic anhydride and 11 parts of triethylamine were added to the polyamic acid solution and stirred for 18 h. Then, sufficient methanol was added to the reaction system to precipitate the precipitate. After filtration and washing, the precipitate was vacuum dried at 280°C for 18 h to obtain polyimide;

[0094] Step 3. Preparation of high heat-resistant battery separator: (1) Add polyimide and Irgacure 2959 to dimethylacetamide, stir and mix evenly to obtain a coating solution with a solid content of 10wt%; (2) Coat the coating solution evenly on both surfaces of the modified porous silica fiber membrane, vacuum dry at 140℃ for 6h, and then crosslink under ultraviolet light at a wavelength of 365nm to obtain a high heat-resistant battery separator with a thickness of 25μm.

[0095] Comparative Example 4: Comparative Example 4 is based on Example 1, with the following adjustment: porous silica-modified polyimide is coated onto an aluminum-plastic film, dried, shaped, and demolded to obtain a high-heat-resistant battery separator. Other processes remain unchanged. Specifically:

[0096] A high heat-resistant battery separator and a method for preparing the battery thereon:

[0097] Step 1.

[0098] 1. Preparation of modified porous silica: (1) 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol were added to the reaction vessel, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred for 20 min to obtain an amino silane hydrolysate (the mass ratio of 3-aminopropyltrimethoxysilane, deionized water and anhydrous ethanol was 1:1:4; the amount of 3-aminopropyltrimethoxysilane added was 3% of the mass of porous silica); (2) Porous silica was added to a stirrer and stirred at a rate of 150 r / min. At the same time, the amino silane hydrolysate was sprayed evenly into it. After spraying, the mixture was stirred for 2 h. After drying, modified porous silica was obtained.

[0099] 2. Preparation of porous silica-modified polyimide: (1) 9.4 parts (0.47 mol) of 4,4'-diaminodiphenyl ether, 7.15 parts (0.47 mol) of 3,5-diaminobenzoic acid, and 0.68 parts (0.06 mol) of maleic acid diamine were added to 200 parts of dimethylacetamide and stirred until homogeneous. Then, under nitrogen protection, 45 parts (1.01 mol) of hexafluorodianhydride were added to the solution and stirred at 15°C for 24 h to obtain a polyamic acid solution; (2) Under nitrogen protection, 43 parts of acetic anhydride and 11 parts of triethylamine were added to the polyamic acid solution and stirred. The reaction was carried out for 18 hours; then, sufficient methanol was added to the reaction system to precipitate the precipitate. After filtration and washing, the precipitate was dried under vacuum at 280°C for 18 hours to obtain polyimide; (3) Under nitrogen protection, the polyimide obtained in (2), 9.5 parts of dicyclohexylcarbodiimide, and 4.75 parts of 4-dimethylaminopyridine were added to 100 parts of dimethylacetamide and stirred and mixed evenly. Then, 7 parts of modified porous silica were added to the solution and stirred for 24 hours. Then, sufficient methanol was added to the reaction system to precipitate the precipitate. After filtration and washing, the precipitate was dried under vacuum at 140°C for 6 hours to obtain porous silica-modified polyimide;

[0100] Step 2. Preparation of high heat-resistant battery separator: (1) Add porous silica-modified polyimide to dimethylacetamide, stir and mix evenly to obtain a coating liquid with a solid content of 10wt%; (2) Coat the coating liquid evenly onto the surface of aluminum-plastic film, and after vacuum drying at 140℃ for 6h, remove the aluminum-plastic film to obtain a high heat-resistant battery separator with a thickness of 25μm.

[0101] Performance Test 1: The heat resistance, mechanical properties, and air permeability of the high heat-resistant battery separators prepared in Examples 1-3 and Comparative Examples 1-5 were tested. The specific test methods are as follows:

[0102] (1) Heat resistance performance: The high heat resistance battery separator was cut into square test samples of 20cm×20cm, placed in an oven, and heated and baked at 130℃ for 10min and 410℃ for 10s respectively. The change of its side length was measured and its heat shrinkage rate was calculated to evaluate its heat resistance performance.

[0103] (2) Mechanical properties: The high heat-resistant battery separator was cut into rectangular test samples of 1cm×10cm. The tensile strength was tested longitudinally using a universal testing machine at a speed of 5cm / min to evaluate its mechanical properties.

[0104] (3) Air permeability: At a temperature of 23℃ and a pressure of 1.22kPa, dry nitrogen was used as the test gas, and the air permeability of the high heat-resistant battery separator was tested using a BTY-B2P air permeability tester.

[0105] The test data results for the high heat-resistant battery separator are shown in Table 1 below:

[0106] Table 1

[0107]

[0108] Results Analysis: As shown in Table 1 above, this invention comprehensively prepares a battery separator with high heat shrinkage resistance, excellent tensile strength, and excellent air permeability through the combination of resin and matrix. In this invention, by introducing polystyrene nanospheres into the silica spinning solution, the resulting porous silica fiber membrane possesses a certain pore structure, which effectively enhances the heat shrinkage rate and air permeability of the high heat-resistant battery separator. Modification treatment of the porous silica fiber membrane enhances the bonding between the porous silica-modified polyimide and the membrane, which has a certain impact on the tensile strength and air permeability of the high heat-resistant battery separator. Furthermore, the modification of polyimide by porous silica has a significant modifying effect on the heat shrinkage rate and tensile strength of the high heat-resistant battery separator.

[0109] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high heat-resistant battery separator, characterized in that: Includes the following steps: Step 1. Preparation of modified porous silica fiber membrane: (1) A porous silica fiber membrane was obtained by electrospinning and calcining a silica spinning solution containing polystyrene nanospheres. (2) The porous silica fiber membrane was modified with a vinyl silane coupling agent to obtain a modified porous silica fiber membrane; Step 2. Preparation of porous silica-modified polyimide: (1) Add hexafluorodianhydride to a mixed solution containing 4,4'-diaminodiphenyl ether, 3,5-diaminobenzoic acid and maleic acid diamine, stir and react to obtain a polyamic acid solution; (2) Add acetic anhydride and triethylamine to the polyamic acid solution, stir to react, add methanol to precipitate, filter, wash and vacuum dry to obtain polyimide; (3) Polyimide is grafted with modified porous silica to obtain porous silica-modified polyimide; Step 3. Preparation of a high heat-resistant battery separator: (1) Add porous silica-modified polyimide and photoinitiator to dimethylacetamide, stir and mix evenly to obtain a coating solution with a solid content of 5-15 wt%. (2) The liquid to be coated is uniformly coated onto both surfaces of the modified porous silica fiber membrane, and after vacuum drying and ultraviolet crosslinking, a high heat-resistant battery separator is obtained.

2. The method for preparing a high heat-resistant battery separator according to claim 1, characterized in that: The method for preparing the modified porous silica fiber membrane is as follows: (1) Disperse polystyrene nanospheres in deionized water, and then add tetraethyl orthosilicate and oxalic acid at 30-50°C. After the addition is complete, continue stirring to hydrolyze for 6-12 hours to obtain silica spinning solution. (2) The silica spinning solution is electrospun to obtain a silica fiber membrane; (3) The silica fiber membrane is placed in a muffle furnace and calcined to obtain a porous silica fiber membrane; (4) Add vinyl silane coupling agent, deionized water and anhydrous ethanol into the reaction vessel, and add acetic acid to adjust the pH of the solution to 4-6. Stir and mix for 10-30 min to obtain vinyl silane hydrolysate. (5) Soak the porous silica fiber membrane in a vinyl silane hydrolysate for 30-60 minutes, remove it and vacuum dry it to obtain a modified porous silica fiber membrane.

3. The method for preparing a high heat-resistant battery separator according to claim 2, characterized in that: The mass ratio of the polystyrene nanospheres, tetraethyl orthosilicate, oxalic acid, and deionized water is (1-3):6:(0.02-0.06):

50. The polystyrene nanospheres have a particle size of 20–50 nm; The parameters for electrospinning are: spinning voltage of 15-25kV, receiving distance of 15-20cm, and injection speed of 0.5-1.5mL / h. The thickness of the silica fiber membrane is 4–10 μm; The calcination parameters are: heating to 450-550℃ at a heating rate of 2-10℃ / min and calcining for 3-9 hours; The mass ratio of the vinyl silane coupling agent, deionized water, and anhydrous ethanol is 1:1:

4. The vinyl silane coupling agent includes any one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(2-methoxyethoxy)silane, vinyltriisopropoxysilane, and vinyldimethylethoxysilane.

4. The method for preparing a high heat-resistant battery separator according to claim 1, characterized in that: The method for preparing the porous silica-modified polyimide is as follows: (1) Add 4,4'-diaminodiphenyl ether, 3,5-diaminobenzoic acid and maleic acid diamine to dimethylacetamide, stir and mix evenly, then add hexafluorodianhydride to the solution under nitrogen protection, and stir and react at 10-20℃ for 12-36h to obtain polyamic acid solution. (2) Under nitrogen protection, acetic anhydride and triethylamine were added to the polyamic acid solution and stirred for 12-24 h. Then, sufficient methanol was added to the reaction system to precipitate the precipitate. After filtration and washing, the precipitate was dried under vacuum at 250-300℃ for 12-24 h to obtain polyimide. (3) Under nitrogen protection, polyimide, dicyclohexylcarbodiimide and 4-dimethylaminopyridine were added to dimethylacetamide and stirred until homogeneous. Modified porous silica was then added to the solution and stirred for 12-36 hours. Sufficient methanol was then added to the reaction system to precipitate the precipitate. After filtration, washing and vacuum drying, porous silica-modified polyimide was obtained.

5. The method for preparing a high heat-resistant battery separator according to claim 4, characterized in that: The raw materials required for the preparation of porous silica-modified polyimide It comprises the following components by weight: 9.2–9.6 parts of 4,4'-diaminodiphenyl ether, 7–7.3 parts of 3,5-diaminobenzoic acid, 0.46–0.92 parts of maleic diamine, 44.4–46.6 parts of hexafluorodianhydride, 40–45 parts of acetic anhydride, 10–12 parts of triethylamine, 9–10 parts of dicyclohexylcarbodiimide, 4.5–5 parts of 4-dimethylaminopyridine, 6–8 parts of modified porous silica, and 300 parts of dimethylacetamide.

6. The method for preparing a high heat-resistant battery separator according to claim 4, characterized in that: The method for preparing the modified porous silica is as follows: (1) Add amino silane coupling agent, deionized water and anhydrous ethanol into the reaction vessel, and add acetic acid to adjust the pH of the solution to 4-6. Stir and mix for 10-30 min to obtain amino silane hydrolysate. (2) Add porous silica into a mixer and stir at a rate of 100-200 r / min. At the same time, spray amino silane hydrolysate evenly into it. After spraying, continue stirring and mixing for 1-3 hours. After drying, modified porous silica is obtained.

7. The method for preparing a high heat-resistant battery separator according to claim 6, characterized in that: The mass ratio of the amino-based silane coupling agent, deionized water, and anhydrous ethanol is 1:1:

4. The amount of the amino-based silane coupling agent added is 1-5% of the mass of porous silica; The amino-based silane coupling agent includes any one of 3-aminopropyltrimethoxysilane, bis[(3-trimethoxysilyl)propyl]amine, 3-aminopropyltriethoxysilane, bis[(3-triethoxysilyl)propyl]amine, 3-aminopropylmethyldimethoxysilane, and 3-aminopropylmethyldiethoxysilane.

8. The method for preparing a high heat-resistant battery separator according to claim 1, characterized in that: The amount of photoinitiator added is 1-3% of the mass of porous silica-modified polyimide; The parameters for the ultraviolet crosslinking are: ultraviolet wavelength of 300-400 nm; The thickness of the high heat-resistant battery separator is 16–30 μm.

9. A method for preparing a battery, characterized in that: The high heat-resistant battery separator prepared by the method of any one of claims 1 to 8 is wound and assembled with positive electrode active material and negative electrode active material, and then injected with electrolyte to obtain a battery.

Images