CN114824647B - Lithium ion battery diaphragm based on aluminum hydroxide coaxial nanotubes and preparation method thereof - Google Patents

Abstract

The invention provides a lithium ion battery diaphragm based on an aluminum hydroxide coaxial nanotube and a preparation method thereof, and glucose derived C@ porous Al (OH) is introduced into the diaphragm ₃ The coaxial nano tube improves the mechanical strength and the heat shrinkage performance of the diaphragm, and greatly enhances the liquid absorption and retention capacity of the diaphragm; the COPNA resin is used as the binder to effectively improve the complexity of macromolecular crosslinked network in the diaphragm, and has excellent affinity with the carbon material to effectively improve the glucose derivative C@ porous Al (OH) ₃ The affinity of the coaxial nanotube to the diaphragm effectively prolongs the service life of the diaphragm; bamboo tar is selected as a raw material, terephthalyl alcohol is used as a cross-linking agent, and p-toluenesulfonic acid is used as a catalyst to synthesize COPNA resin; the adhesive is modified, so that the heat shrinkage, flame retardance and ionic conductivity of the diaphragm are effectively improved; introducing DOPO and derivatives thereof, octaaminopropyl cage-type silsesquioxane and glucose derived C@ porous Al (OH) ₃ The coaxial nano tube is compounded with a plurality of flame-retardant elements to realize synergistic flame retardance, so that the safety of the diaphragm is effectively improved.

Description

Lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes and preparation method thereof

Technical field

The present invention relates to the field of battery separators, specifically a lithium ion battery separator based on aluminum hydroxide coaxial nanotubes and a preparation method thereof.

Background technique

Lithium battery is a new type of secondary battery with the advantages of high energy density and long cycle life. It is widely used in portable electronic devices, energy storage, and power vehicles. With the development of the new energy industry, more and more Lithium batteries are used in power vehicles. The separator is an important part of the lithium battery. It effectively prevents short circuits between the positive and negative electrodes and ensures the safety of the lithium battery. Therefore, there are higher requirements for the performance of the separator.

Polyolefin separators are currently the most widely used lithium battery separators. However, the polyolefin separators currently on the market also have the following shortcomings: ① Low ionic conductivity increases the internal resistance of the battery, which is not conducive to the charging of lithium ion batteries at high rates. Discharge; ②Poor bonding performance of the counter electrode piece and insufficient electrolyte performance cause the battery to have problems such as poor battery hardness, poor cycle performance, low thermal stability, and unstable interface between the electrode piece and the separator, which greatly limits the battery energy The increase in density and the development of high-performance ultra-thin batteries; ③ When thermal runaway occurs in the battery, the melting point of polyolefin materials is very low, and the polyolefin separator is prone to rupture, leading to aggravation of thermal runaway, causing the battery to burn or even explode.

Therefore, the development of lithium-ion battery separators with high ionic conductivity, high electrolyte wettability and high flame retardancy has become a common goal pursued by the industry.

Contents of the invention

The purpose of the present invention is to solve the problems in the prior art by lithium-ion battery separators based on aluminum hydroxide coaxial nanotubes and preparation methods thereof.

In order to solve the above technical problems, the present invention provides the following technical solutions:

A lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes includes a base film and a coating layer formed on the surface of the base film; in terms of parts by mass, the content of each component in the coating layer is: 0.35%-0.8 % dispersant, 9%-23% glucose-derived C@porous Al(OH) ₃ coaxial nanotubes, 0.2%-0.85% thickener, 0.6%-1.3% binder, 0.1%-0.4 % wetting agent, the balance is deionized water.

In order to solve the problem of poor adhesion and electrolyte wettability of the existing polyolefin separator to the electrode piece, the current main solution is to coat one or both sides of the polyolefin separator with a water-based PVDF adhesive layer. This adhesive layer It can effectively improve the adhesion of the separator and has good wettability with the electrolyte, but it has the problem of easy falling off. For the problems of low ionic conductivity and poor heat resistance of polyolefin separators, the current main solution is to use polyolefin separators. Coating one or both sides of an olefin separator with a high-temperature resistant ceramic coating can delay the closure of the separator to 150°C. However, the closing temperature of 150°C cannot completely prevent short circuits and spontaneous combustion of lithium batteries at high temperatures. Therefore, It is necessary to further improve the heat resistance of the separator and reduce the risk of separator rupture to improve battery safety.

In the lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes provided by the present invention, glucose-derived C nanotubes are selected as coating materials and added to the slurry components, wherein the glucose-derived C nanotubes have good high temperature resistance and thermal conductivity. , which is conducive to improving the heat resistance of the coating, thereby improving the heat resistance of the separator.

Further, the preparation of glucose-derived C nanotubes includes the following steps:

Add the hydrophilic treated silica nanowires to the glucose solution under constant stirring conditions, continue magnetic stirring for 40-50 minutes, and then perform ultrasonic dispersion for 6-7 hours, and transfer to a PTFE-lined stainless steel autoclave. And heated at 95-100℃ for 5-6h, naturally cooled to 18-25℃, filtered, washed with absolute ethanol and deionized water, dried at 70-80℃ for 20-24h, with a vacuum of 0.08Mpa, to obtain Carbon-coated silica nanowire coaxial composite material; add the carbon-coated silica nanowire coaxial composite material to 5.0 mol/L sodium hydroxide solution and keep it for 5-6 hours, then filter, wash and place Dry at 70-80°C for 10-12 hours, and obtain glucose-derived C nanotubes after drying.

Furthermore, the mass molar ratio of the hydrophilic treated silica nanowires to the glucose in the glucose solution is 92 mg:101.4 mmol.

The preparation of hydrophilic treated silica nanowires includes the following steps: mix and stir cetyltrimethylammonium bromide, absolute ethanol, and deionized water, add ammonia solution and 0.1g ethyl orthosilicate, Add 6% mass fraction of (3-mercaptopropyl) trimethoxysilane, immerse the indium tin oxide coated substrate, leave it at 55-58°C for 28 hours, wash, and age at 100°C, using 0.15mol/L hydrochloric acid Wash with ethanol solution, and then treat with hydrogen peroxide solution to obtain sulfonated silica deposited on the indium tin oxide coating substrate, which is removed, dried and ground to obtain hydrophilic treated silica nanowires.

The sulfonic acid group is loaded on the vertical mesoporous silica pores in situ without changing the pore structure. The selective permeability of the nanochannel is mainly caused by the size effect and charge effect. When the nanochannel is completely occupied by the electric double layer , the selective permeability is the best. The present invention effectively improves the ionic conductivity of the membrane by limiting the preparation and introduction of hydrophilic treated silica nanowires.

Further, the preparation of glucose-derived C@porous Al(OH) ₃ coaxial nanotubes includes the following steps: magnetically stir the glucose-derived C nanotubes and ultrapure water for 80-90 minutes, then conduct ultrasonic dispersion for 190-200 minutes, and add aluminum sulfate. , continue to stir the urea until dissolved, raise the temperature to 90-95C and react for 12-15h, suction filter, wash with ultrapure water, place in a vacuum dryer at 75-80℃ for 32-36h, after drying, dry at 2℃/ The heating rate was raised to 115-120°C for 1 min, kept at a constant temperature for 150-155 min, and then cooled to obtain glucose-derived C@ porous Al(OH) ₃ coaxial nanotubes.

Furthermore, the mass ratio of glucose-derived C nanotubes, aluminum sulfate, and urea is 1.97:13.46:26.59.

Lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes, in which the introduction of glucose-derived C@porous Al(OH) ₃ coaxial nanotubes benefits from its excellent properties and the cross-linking between different nanotubes. The mechanical strength and heat shrinkage performance of the separator are greatly improved; in addition, the glucose-derived C nanotubes and the porous Al(OH) ₃ with flame retardant properties can work synergistically, which further improves the mechanical properties and heat shrinkage performance of the separator;

The introduction of glucose-derived C nanotubes on the one hand increases the mechanical properties of the separator, and on the other hand enhances the conductive properties of the separator, which is beneficial to enhancing the rapid transmission of lithium ions; in addition, the glucose-derived C@porous Al(OH) ₃ The shaft nanotube has a hollow structure as a whole, and the outer coating of Al(OH) ₃ has a porous structure, which further improves the lithium ion conductivity and greatly increases the specific surface area of the material, thereby greatly enhancing the liquid absorption and retention properties of the separator. liquid capacity.

The Al(OH) ₃ introduced into the lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes greatly improves the flame retardant capability of the separator. The crystal water of Al(OH) ₃ decomposes and absorbs heat to form a carbonized layer. When the temperature When it rises to the decomposition temperature, Al(OH) ₃ decomposes and releases water vapor, absorbs latent heat, and dilutes the concentration of oxygen and combustible gases near the surface of the burning material, making surface combustion difficult; and the carbonized layer formed on the surface prevents oxygen and heat from entering. , at the same time, the alumina produced by its decomposition is also a good refractory material, with good high temperature resistance and thermal conductivity, which can improve the material's ability to resist open flames.

Further, the base film is a polyolefin separator; the dispersant is a hydrolyzed polymaleic anhydride dispersant, the thickener is a sodium hydroxymethylcellulose dispersant, and the binder is a COPNA resin adhesive. The wetting agent is a silanol nonionic surfactant.

A method for preparing a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes, including the following steps:

S1: Premix the dispersant and glucose-derived C@porous Al(OH) ₃ coaxial nanotubes in ultrapure water for 10-90 min, with a rotation speed of 100-600 rpm; add the thickener and continue stirring for 10-90 min, with a rotation speed of 350-350 min. 900rpm; add binder and continue stirring for 40-120min, the rotation speed is 350-700rpm; add wetting agent and stir for 30-90min, the rotation speed is 400-900rpm; after filtering and removing iron, glucose-derived C@porous Al(OH) ₃ is obtained Shaft nanotube coating slurry;

S2: Using a microgravure roller coating process, the prepared glucose-derived C@porous Al(OH) ₃ coaxial nanotube coating slurry is rolled on both sides of the base film in steps, and baked at 65-70°C Afterwards, it is rolled up to obtain a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes.

Using COPNA resin as a binder can effectively improve the complexity of the macromolecular cross-linked network in the separator, and COPNA resin has excellent affinity with carbon materials, effectively improving the efficiency of glucose-derived C@porous Al(OH) ₃ coaxial nanoparticles. The affinity between the tube and the diaphragm effectively extends the service life of the diaphragm.

The existing market mostly uses COPNA resin, a non-renewable petrochemical raw material. Not only is the process complicated and the processing process polluting, but the high density of monomer fused rings and high steric hindrance lead to low cross-linking density, poor carbon residue rate and poor heat resistance.

The invention uses bamboo as a renewable raw material, bamboo tar as the raw material, terephthalyl alcohol as the cross-linking agent, and p-toluenesulfonic acid as the catalyst to synthesize COPNA resin. The pretreatment process is simple, the cost is low, and the emission of waste is reduced. .

Further, the preparation of COPNA resin includes the following steps: in a nitrogen environment, weigh bamboo tar and terephthalyl alcohol in a mass ratio of 1:1, add p-toluenesulfonic acid with a mass fraction of 5.4-6.8%, React at 130-150°C until filament winding occurs, stop heating, and cool the material to obtain COPNA resin.

In an acidic environment, terephthalenedimethanol will produce active carbocation, which will undergo an electrophilic substitution reaction with a large number of phenols in bamboo tar and the benzene ring in its derivatives. The alcoholic hydroxyl group in the generated product will be dehydrated under the action of acid. Carbocation is generated again, and the carbocation reacts with aromatic hydrocarbons to form cross-linked macromolecules. As the degree of cross-linking deepens, the viscosity of the system increases, and water vapor no longer escapes, and cross-links into a network structure to obtain COPNA resin. , improving the softening point and heat resistance of the COPNA resin obtained by controlling the addition amount of p-toluenesulfonic acid.

The binder is modified to effectively improve the binding force between glucose-derived C@porous Al(OH) ₃ coaxial nanotubes, thickeners, binders, and wetting agents, and effectively improve the thermal shrinkage of the separator. , flame retardancy and ionic conductivity.

Further, the binder is modified COPNA resin, and the preparation includes the following steps:

(1) In a nitrogen environment, react itaconic acid, deionized water, and 1,6-hexanediamine at 55-60°C for 20-30 minutes to obtain an itaconic acid mixture;

(2) Mix deionized water, absolute ethanol, acetonitrile, triethylamine, and tetraethylammonium hydroxide in a constant temperature water bath at 52-56°C; add 3-aminopropyltriethoxysilane, and mix at 52-56 ℃ reflux for 20-22 hours, distill and concentrate under reduced pressure, add the concentrated solution to petroleum ether, let it stand, filter under reduced pressure, wash with acetone 2-5 times, and obtain octaaminopropyl cage silsesquioxide after vacuum drying. alkyl;

(3) Mix and stir the DOPO and itaconic acid mixture, raise the temperature to 85-88°C and react for 2.5-3 hours; filter with suction while hot, cool to 18-25°C, transfer to an ice water bath to cool for 9-11 hours, and filter with suction to obtain Water-soluble flame retardant; add octaaminopropyl cage silsesquioxane and COPNA resin and stir ultrasonically for 30-60 minutes to obtain modified COPNA resin.

Further, the molar volume ratio of itaconic acid, 1,6-hexanediamine, and deionized water is 0.2mol:0.2mol:320mL; the deionized water, absolute ethanol, acetonitrile, triethylamine, and tetraethyl The volume ratio of ammonium hydroxide is 80mL:36mL:9mL:9mL:5mL; the molar ratio of DOPO and itaconic acid is 1.2:1.

DOPO is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide;

Cage silsesquioxane has high thermal oxidation stability and excellent mechanical properties; in the present invention, DOPO and its derivatives, octaaminopropyl cage silsesquioxane, and glucose-derived C@porous Al(OH) are introduced. ₃ Coaxial nanotubes are compounded with multiple flame retardant elements to achieve synergistic flame retardancy;

On the basis of the carbonization layer formed by the thermal decomposition and endotherm of the crystal water of Al(OH) ₃ , combined with DOPO and its derivatives, it can be decomposed to produce oxyphosphoric acid to promote dehydration and carbonization of the material. Silica particles can coat the surface and together create a synergistic flame retardant effect.

In the present invention, the three are used synergistically for the flame retardancy of the separator, and the silica particles produced by the decomposition of cage silsesquioxane are used to enhance the quality and strength of the carbon layer formed by DOPO and its derivatives and Al(OH) ₃ catalysis. , can form a stable ceramic layer containing silica and alumina composite, enhance the stability of the carbon layer, block the contact of external heat flow and oxygen with internal materials and flammable gases, thereby preventing the combustion reaction from proceeding, and greatly improving the synergy Flame retardant properties of the diaphragm.

The COPNA resin is modified to introduce P-H bonds into the COPNA resin, which is extremely active on the olefins, epoxy bonds, and carbonyl groups in the separator raw materials, greatly improving the heat shrinkage of the separator; and the introduction of active sites is conducive to improving the separator The ion exchange capacity effectively prevents the risk of thermal runaway and improves the safety of the diaphragm.

COPNA resin is a condensed polycyclic polynuclear aromatic resin; DOPO is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

Beneficial effects of the present invention:

The invention provides a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes and a preparation method thereof. Through component limitation and process adjustment, a lithium-ion battery with high liquid absorption and liquid retention capacity, high flame retardancy and high safety is prepared. battery separator;

Among them, the introduction of glucose-derived C@porous Al(OH) ₃ coaxial nanotubes has greatly improved the mechanical strength and heat shrinkage performance of the separator; the introduction of glucose-derived C nanotubes on the one hand increases the mechanical properties of the separator, and on the other hand The conductive properties of the separator are also enhanced, and the hydrophilic treatment of silica is conducive to enhancing the rapid transmission of lithium ions; in addition, the glucose-derived C@porous Al(OH) ₃ coaxial nanotubes have a hollow structure as a whole, and are covered with Al(OH) ₃ presents a porous structure, which further improves the lithium ion conductivity and greatly increases the specific surface area of the material, thus greatly enhancing the separator's ability to absorb and retain liquid;

Using COPNA resin as a binder can effectively improve the complexity of the macromolecular cross-linked network in the separator, and COPNA resin has excellent affinity with carbon materials, effectively improving the efficiency of glucose-derived C@porous Al(OH) ₃ coaxial nanoparticles. The affinity between the tube and the diaphragm effectively extends the service life of the diaphragm;

The invention uses bamboo as a renewable raw material, selects bamboo tar as the raw material, terephthalyl alcohol as the cross-linking agent, and p-toluenesulfonic acid as the catalyst to synthesize COPNA resin, and improves the properties of the COPNA resin obtained by controlling the addition amount of p-toluenesulfonic acid. Softening point and heat resistance, the pretreatment process is simple, low cost, and reduces waste emissions;

The binder is modified to effectively improve the binding force between glucose-derived C@porous Al(OH) ₃ coaxial nanotubes, thickeners, binders, and wetting agents, and effectively improve the thermal shrinkage of the separator. , flame retardancy and ionic conductivity;

In the present invention, DOPO and its derivatives, octaaminopropyl cage silsesquioxane, glucose-derived C@porous Al(OH) ₃ coaxial nanotubes, and multiple flame retardant elements are introduced to achieve synergistic flame retardancy; The three are used synergistically for the flame retardancy of the separator, and the silica particles produced by the decomposition of cage silsesquioxane are used to enhance the quality and strength of the carbon layer formed by DOPO and its derivatives and Al(OH) ₃ catalysis, which can form A stable ceramic layer composed of silica and alumina enhances the stability of the carbon layer, blocks external heat flow and oxygen from contact with internal materials and flammable gases, thereby preventing the combustion reaction from proceeding, and synergistically greatly improving the resistance of the diaphragm. combustion performance; and the introduction of a large number of active sites is conducive to improving the ion exchange capacity of the membrane and effectively improving the safety of the membrane.

Detailed ways

The technical solutions in the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

It should be noted that if the embodiments of the present invention involve directional indications such as up, down, left, right, front, back, etc., then the directional indications are only used to explain a specific posture such as the relative relationship between components. Positional relationship, movement conditions, etc., if the specific posture changes, the directional indication will also change accordingly. In addition, the technical solutions in various embodiments can be combined with each other, but it must be based on the realization by those of ordinary skill in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that such a combination of technical solutions does not exist. , nor within the protection scope required by the present invention.

The technical solution of the present invention will be further described in detail below with reference to specific examples. It should be understood that the following examples are only used to explain the present invention and are not intended to limit the present invention.

Example 1

A method for preparing a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes, including the following steps:

S1: Premix the dispersant and glucose-derived C@porous Al(OH) ₃ coaxial nanotubes in ultrapure water for 10 minutes at a rotation speed of 600 rpm; add the thickening agent and continue stirring for 10 minutes at a rotation speed of 900 rpm; add the binder and continue stirring 40min, the rotation speed is 700rpm; add wetting agent and stir for 30min, the rotation speed is 900rpm; filter and remove iron to obtain glucose-derived C@porous Al(OH) ₃ coaxial nanotube coating slurry;

A lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes includes a base film and a coating layer coated on the surface of the base film; in terms of parts by mass, the content of each component in the coating layer is: 0.35% Dispersant, 9% glucose-derived C@porous Al(OH) ₃ coaxial nanotubes, 0.2% thickener, 0.6% binder, 0.1% wetting agent, the balance is deionized water;

The base film is a polyethylene separator; the dispersant is hydrolyzed polymaleic anhydride, the thickener is sodium carboxymethylcellulose, the binder is COPNA resin, and the wetting agent is a silanol nonionic surfactant;

The preparation of glucose-derived C nanotubes includes the following steps:

Under constant stirring conditions, 92 mg of hydrophilic-treated silica nanowires were added to a glucose solution containing 101.4 mmol glucose, continued magnetic stirring for 40 min, and then ultrasonically dispersed for 7 h, and then transferred to a PTFE-lined stainless steel autoclave. in, and heated at 95°C for 6 hours, naturally cooled to 18°C, filtered, washed with absolute ethanol and deionized water, and dried at 70°C for 24 hours with a vacuum of 0.08Mpa to obtain carbon-coated silica nanowires. Coaxial composite material; add the carbon-coated silica nanowire coaxial composite material to 5.0 mol/L sodium hydroxide solution and keep it for 5 hours, then filter, wash and dry at 70°C for 10 hours. After drying, glucose is obtained Derivatized C nanotubes;

The preparation of glucose-derived C@porous Al(OH) ₃ coaxial nanotubes includes the following steps: magnetically stir 1.97g glucose-derived C nanotubes and 215 mL of ultrapure water for 80 min, then conduct ultrasonic dispersion for 200 min, add 13.46 g of aluminum sulfate, Continue to stir 26.59g of urea until dissolved, raise the temperature to 90°C and react for 15 hours. Filter, wash with ultrapure water, and dry in a vacuum at 75°C for 36 hours. After drying, increase the temperature from 18°C to 115°C at a rate of 2°C/min. Keep the temperature constant for 155 minutes and cool to obtain glucose-derived C@porous Al(OH) ₃ coaxial nanotubes;

The preparation of hydrophilic treated silica nanowires includes the following steps: mix and stir 0.16g cetyltrimethylammonium bromide, 30mL absolute ethanol, and 70mL deionized water, add 9 μL ammonia solution, 0.1g normal Ethyl silicate, add 6% mass fraction of (3-mercaptopropyl) trimethoxysilane, immerse the indium tin oxide coated substrate, leave it at 55°C for 28 hours, wash, and age at 100°C, use 0.15 mol /L hydrochloric acid ethanol solution, and then treated with hydrogen peroxide solution to obtain sulfonated silica deposited on the indium tin oxide coating substrate, which is removed, dried and ground to obtain hydrophilic treated silica nanowires;

S2: Using a micro-gravure roller coating process, the prepared glucose-derived C@porous Al(OH) ₃ coaxial nanotube coating slurry is coated on both sides of the 9 μm base film by a coater on one side in a step-by-step manner. The coating thickness is 3 μm, and it is baked at 65°C and then rolled up to obtain a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes.

Example 2

A method for preparing a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes, including the following steps:

S1: Premix the dispersant and glucose-derived C@porous Al(OH) ₃ coaxial nanotubes in ultrapure water for 60 minutes at a rotation speed of 400 rpm; add the thickening agent and continue stirring for 70 minutes at a rotation speed of 500 rpm; add the binder and continue stirring 80min, the rotation speed is 600rpm; add wetting agent and stir for 80min, the rotation speed is 800rpm; filter and remove iron to obtain glucose-derived C@porous Al(OH) ₃ coaxial nanotube coating slurry;

A lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes includes a base film and a coating layer coated on the surface of the base film; in terms of parts by mass, the content of each component in the coating layer is: 0.6% Dispersant, 20% glucose-derived C@porous Al(OH) ₃ coaxial nanotubes, 0.8% thickener, 1% binder, 0.3% wetting agent, the balance is deionized water;

The base film is a polyethylene separator; the dispersant is hydrolyzed polymaleic anhydride, the thickener is sodium carboxymethylcellulose, the binder is COPNA resin, and the wetting agent is a silanol nonionic surfactant;

The preparation of glucose-derived C nanotubes includes the following steps:

Under constant stirring conditions, 92 mg of hydrophilic-treated silica nanowires were added to a glucose solution containing 101.4 mmol glucose, continued magnetic stirring for 45 min, and then ultrasonically dispersed for 6.5 h, and then transferred to a PTFE-lined stainless steel high-pressure kettle, and heated at 98°C for 5.5h, naturally cooled to 20°C, filtered, washed with absolute ethanol and deionized water, dried at 75°C for 22h, with a vacuum of 0.08Mpa, to obtain carbon-coated silica Nanowire coaxial composite material; add the carbon-coated silica nanowire coaxial composite material to 5.0mol/L sodium hydroxide solution and keep it for 5.5h, then filter, wash and dry at 75°C for 11h, dry Finally, glucose-derived C nanotubes are obtained;

The preparation of glucose-derived C@porous Al(OH) ₃ coaxial nanotubes includes the following steps: magnetically stir 1.97g glucose-derived C nanotubes and 215 mL of ultrapure water for 85 min, then conduct ultrasonic dispersion for 195 min, add 13.46 g of aluminum sulfate, Continue to stir 26.59g of urea until dissolved, raise the temperature to 90-95C and react for 12-15h, filter with suction, wash with ultrapure water, and place in a vacuum dryer at 78°C for 34h. After drying, the temperature rises from 20°C at a rate of 2°C/min. to 118°C, kept at a constant temperature for 152 minutes, and cooled to obtain glucose-derived C@porous Al(OH) ₃ coaxial nanotubes;

The preparation of hydrophilic treated silica nanowires includes the following steps: mix and stir 0.16g cetyltrimethylammonium bromide, 30mL absolute ethanol, and 70mL deionized water, add 9 μL ammonia solution, 0.1g normal Ethyl silicate, add 6% mass fraction of (3-mercaptopropyl) trimethoxysilane, immerse the indium tin oxide coated substrate, let stand at 56°C for 28h, wash, age at 100°C, use 0.15mol /L hydrochloric acid ethanol solution, and then treated with hydrogen peroxide solution to obtain sulfonated silica deposited on the indium tin oxide coating substrate, which is removed, dried and ground to obtain hydrophilic treated silica nanowires;

S2: Using a micro-gravure roller coating process, the prepared glucose-derived C@porous Al(OH) ₃ coaxial nanotube coating slurry is coated on both sides of the 9 μm base film by a coater on one side in a step-by-step manner. The coating thickness is 3 μm, and it is baked at 68°C and then rolled up to obtain a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes.

Example 3

A method for preparing a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes, including the following steps:

S1: Premix the dispersant and glucose-derived C@porous Al(OH) ₃ coaxial nanotubes in ultrapure water for 90 min at a rotation speed of 100 rpm; add the thickener and continue stirring for 90 min at a rotation speed of 350 rpm; add the binder and continue stirring 120min, rotating speed is 350rpm; add wetting agent and stir for 90min, rotating speed is 400rpm; filter and remove iron to obtain glucose-derived C@porous Al(OH) ₃ coaxial nanotube coating slurry;

A lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes includes a base film and a coating layer coated on the surface of the base film; in terms of parts by mass, the content of each component in the coating layer is: 0.8% Dispersant, 23% glucose-derived C@porous Al(OH) ₃ coaxial nanotubes, 0.85% thickener, 1.3% binder, 0.4% wetting agent, the balance is deionized water;

The base film is a polyethylene separator; the dispersant is hydrolyzed polymaleic anhydride, the thickener is sodium carboxymethylcellulose, the binder is COPNA resin, and the wetting agent is a silanol nonionic surfactant;

The preparation of glucose-derived C nanotubes includes the following steps:

Add 92 mg of hydrophilic treated silica nanowires to a glucose solution containing 101.4 mmol glucose under constant stirring, continue magnetic stirring for 50 min, and then conduct ultrasonic dispersion for 6 h, and transfer to a PTFE-lined stainless steel autoclave. in, and heated at 100°C for 5 hours, naturally cooled to 25°C, filtered, washed with absolute ethanol and deionized water, and dried at 80°C for 20 hours with a vacuum of 0.08Mpa to obtain carbon-coated silica nanowires. Coaxial composite material; add the carbon-coated silica nanowire coaxial composite material to 5.0 mol/L sodium hydroxide solution and keep it for 6 hours, then filter, wash and dry at 80°C for 10 hours. After drying, glucose is obtained Derivatized C nanotubes;

The preparation of glucose-derived C@porous Al(OH) ₃ coaxial nanotubes includes the following steps: magnetically stir 1.97g glucose-derived C nanotubes and 215 mL of ultrapure water for 90 min, then perform ultrasonic dispersion for 200 min, add 13.46 g of aluminum sulfate, Continue to stir 26.59g of urea until dissolved, raise the temperature to 95°C and react for 12 hours. Filter, wash with ultrapure water, and dry in a vacuum at 80°C for 32 hours. After drying, increase the temperature from 25°C to 120°C at a rate of 2°C/min. Keep the temperature constant for 155 minutes and cool to obtain glucose-derived C@porous Al(OH) ₃ coaxial nanotubes;

The preparation of hydrophilic treated silica nanowires includes the following steps: mix and stir 0.16g cetyltrimethylammonium bromide, 30mL absolute ethanol, and 70mL deionized water, add 9 μL ammonia solution, 0.1g normal Ethyl silicate, add 6% mass fraction of (3-mercaptopropyl)trimethoxysilane, immerse the indium tin oxide coated substrate, let stand at 58°C for 28h, wash, age at 100°C, use 0.15mol /L hydrochloric acid ethanol solution, and then treated with hydrogen peroxide solution to obtain sulfonated silica deposited on the indium tin oxide coating substrate, which is removed, dried and ground to obtain hydrophilic treated silica nanowires;

S2: Using a micro-gravure roller coating process, the prepared glucose-derived C@porous Al(OH) ₃ coaxial nanotube coating slurry is coated on both sides of the 9 μm base film by a coater on one side in a step-by-step manner. The coating thickness is 3 μm, and it is baked at 70°C and then rolled up to obtain a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes.

Example 4

A method for preparing a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes, including the following steps:

S1: Premix the dispersant and glucose-derived C@porous Al(OH) ₃ coaxial nanotubes in ultrapure water for 10 minutes at a rotation speed of 600 rpm; add the thickening agent and continue stirring for 10 minutes at a rotation speed of 900 rpm; add the binder and continue stirring 40min, the rotation speed is 700rpm; add wetting agent and stir for 30min, the rotation speed is 900rpm; filter and remove iron to obtain glucose-derived C@porous Al(OH) ₃ coaxial nanotube coating slurry;

A lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes includes a base film and a coating layer coated on the surface of the base film; in terms of parts by mass, the content of each component in the coating layer is: 0.35% Dispersant, 9% glucose-derived C@porous Al(OH) ₃ coaxial nanotubes, 0.2% thickener, 0.6% binder, 0.1% wetting agent, the balance is deionized water;

The base film is a polyethylene separator; the dispersant is hydrolyzed polymaleic anhydride, the thickener is sodium carboxymethylcellulose, the binder is COPNA resin, and the wetting agent is a silanol nonionic surfactant;

The preparation of glucose-derived C nanotubes includes the following steps:

Under constant stirring conditions, 92 mg of hydrophilic-treated silica nanowires were added to a glucose solution containing 101.4 mmol glucose, continued magnetic stirring for 40 min, and then ultrasonically dispersed for 7 h, and then transferred to a PTFE-lined stainless steel autoclave. in, and heated at 95°C for 6 hours, naturally cooled to 18°C, filtered, washed with absolute ethanol and deionized water, and dried at 70°C for 24 hours with a vacuum of 0.08Mpa to obtain carbon-coated silica nanowires. Coaxial composite material; add the carbon-coated silica nanowire coaxial composite material to 5.0 mol/L sodium hydroxide solution and keep it for 5 hours, then filter, wash and dry at 70°C for 10 hours. After drying, glucose is obtained Derivatized C nanotubes;

The preparation of glucose-derived C@porous Al(OH) ₃ coaxial nanotubes includes the following steps: magnetically stir 1.97g glucose-derived C nanotubes and 215 mL of ultrapure water for 80 min, then conduct ultrasonic dispersion for 200 min, add 13.46 g of aluminum sulfate, Continue to stir 26.59g of urea until dissolved, raise the temperature to 90°C and react for 15 hours. Filter, wash with ultrapure water, and dry in a vacuum at 75°C for 36 hours. After drying, increase the temperature from 18°C to 115°C at a rate of 2°C/min. Keep the temperature constant for 155 minutes and cool to obtain glucose-derived C@porous Al(OH) ₃ coaxial nanotubes;

The preparation of hydrophilic treated silica nanowires includes the following steps: mix and stir 0.16g cetyltrimethylammonium bromide, 30mL absolute ethanol, and 70mL deionized water, add 9 μL ammonia solution, 0.1g normal Ethyl silicate, add 6% mass fraction of (3-mercaptopropyl) trimethoxysilane, immerse the indium tin oxide coated substrate, leave it at 55°C for 28 hours, wash, and age at 100°C, use 0.15 mol /L hydrochloric acid ethanol solution, and then treated with hydrogen peroxide solution to obtain sulfonated silica deposited on the indium tin oxide coating substrate, which is removed, dried and ground to obtain hydrophilic treated silica nanowires;

The binder is modified COPNA resin, and the preparation includes the following steps:

(1) In a nitrogen environment, react 0.2 mol of itaconic acid, 320 mL of deionized water, and 0.2 mol of 1,6-hexanediamine at 55°C for 30 minutes to obtain a mixed solution of itaconic acid;

(2) Mix 80 mL of deionized water, 36 mL of absolute ethanol, 9 mL of acetonitrile, 9 mL of triethylamine, and 5 mL of tetraethylammonium hydroxide in a 52°C constant temperature water bath; add 221 mL of 3-aminopropyltriethoxysilane , reflux at 52°C for 22 hours, distill under reduced pressure and concentrate. Add the concentrated solution to petroleum ether, let it stand, filter under reduced pressure, wash with acetone twice, and dry under vacuum to obtain octaaminopropyl cage silsesquioxane. ;

(3) Mix and stir a mixture of 0.24 mol DOPO and 0.2 mol itaconic acid, raise the temperature to 85°C and react for 2.5 hours; filter with suction while hot, cool to 18°C, transfer to an ice water bath and cool for 9 hours, filter with suction to obtain water-soluble resist Fuel agent; add 2g of octaaminopropyl cage silsesquioxane and 10g of COPNA resin and stir ultrasonically for 30 minutes to obtain modified COPNA resin;

The preparation of COPNA resin includes the following steps: in a nitrogen environment, add 2g of bamboo tar and 2g of terephthalol, add 5.4% mass fraction of p-toluenesulfonic acid, react at 130°C until filament winding occurs, stop heating, and discharge Cool to obtain COPNA resin;

S2: Using a micro-gravure roller coating process, the prepared glucose-derived C@porous Al(OH) ₃ coaxial nanotube coating slurry is coated on both sides of the 9 μm base film by a coater on one side in a step-by-step manner. The coating thickness is 3 μm, and it is baked at 65°C and then rolled up to obtain a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes.

Example 5

A method for preparing a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes, including the following steps:

S1: Premix the dispersant and glucose-derived C@porous Al(OH) ₃ coaxial nanotubes in ultrapure water for 60 minutes at a rotation speed of 400 rpm; add the thickening agent and continue stirring for 70 minutes at a rotation speed of 500 rpm; add the binder and continue stirring 80min, the rotation speed is 600rpm; add wetting agent and stir for 80min, the rotation speed is 800rpm; filter and remove iron to obtain glucose-derived C@porous Al(OH) ₃ coaxial nanotube coating slurry;

A lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes includes a base film and a coating layer coated on the surface of the base film; in terms of parts by mass, the content of each component in the coating layer is: 0.6% Dispersant, 20% glucose-derived C@porous Al(OH) ₃ coaxial nanotubes, 0.8% thickener, 1% binder, 0.3% wetting agent, the balance is deionized water;

The base film is a polyethylene separator; the dispersant is hydrolyzed polymaleic anhydride, the thickener is sodium carboxymethylcellulose, the binder is COPNA resin, and the wetting agent is a silanol nonionic surfactant;

The preparation of glucose-derived C nanotubes includes the following steps:

Under constant stirring conditions, 92 mg of hydrophilic-treated silica nanowires were added to a glucose solution containing 101.4 mmol glucose, continued magnetic stirring for 45 min, and then ultrasonically dispersed for 6.5 h, and then transferred to a PTFE-lined stainless steel high-pressure kettle, and heated at 98°C for 5.5h, naturally cooled to 20°C, filtered, washed with absolute ethanol and deionized water, dried at 75°C for 22h, with a vacuum of 0.08Mpa, to obtain carbon-coated silica Nanowire coaxial composite material; add the carbon-coated silica nanowire coaxial composite material to 5.0mol/L sodium hydroxide solution and keep it for 5.5h, then filter, wash and dry at 75°C for 11h, dry Finally, glucose-derived C nanotubes are obtained;

The preparation of glucose-derived C@porous Al(OH) ₃ coaxial nanotubes includes the following steps: magnetically stir 1.97g glucose-derived C nanotubes and 215 mL of ultrapure water for 85 min, then conduct ultrasonic dispersion for 195 min, add 13.46 g of aluminum sulfate, Continue to stir 26.59g of urea until dissolved, raise the temperature to 90-95C and react for 12-15h, filter with suction, wash with ultrapure water, and place in a vacuum dryer at 78°C for 34h. After drying, the temperature rises from 20°C at a rate of 2°C/min. to 118°C, kept at a constant temperature for 152 minutes, and cooled to obtain glucose-derived C@porous Al(OH) ₃ coaxial nanotubes;

The preparation of hydrophilic treated silica nanowires includes the following steps: mix and stir 0.16g cetyltrimethylammonium bromide, 30mL absolute ethanol, and 70mL deionized water, add 9 μL ammonia solution, 0.1g normal Ethyl silicate, add 6% mass fraction of (3-mercaptopropyl) trimethoxysilane, immerse the indium tin oxide coated substrate, let stand at 56°C for 28h, wash, age at 100°C, use 0.15mol /L hydrochloric acid ethanol solution, and then treated with hydrogen peroxide solution to obtain sulfonated silica deposited on the indium tin oxide coating substrate, which is removed, dried and ground to obtain hydrophilic treated silica nanowires;

The binder is modified COPNA resin, and the preparation includes the following steps:

(1) In a nitrogen environment, react 0.2 mol of itaconic acid, 320 mL of deionized water, and 0.2 mol of 1,6-hexanediamine at 58°C for 25 minutes to obtain a mixed solution of itaconic acid;

(2) Mix 80 mL of deionized water, 36 mL of absolute ethanol, 9 mL of acetonitrile, 9 mL of triethylamine, and 5 mL of tetraethylammonium hydroxide in a 54°C constant temperature water bath; add 221 mL of 3-aminopropyltriethoxysilane , reflux at 54°C for 21 hours, distill and concentrate under reduced pressure, add the concentrated solution to petroleum ether, let stand, filter under reduced pressure, wash with acetone 4 times, and obtain octaaminopropyl cage silsesquioxane after vacuum drying ;

(3) Mix and stir a mixture of 0.24 mol DOPO and 0.2 mol itaconic acid, raise the temperature to 87°C and react for 2.6 hours; filter while hot, cool to 22°C, transfer to an ice water bath to cool for 10 hours, and filter with suction to obtain water-soluble resist. Fuel agent; add 2g of octaaminopropyl cage silsesquioxane and 10g of COPNA resin and stir ultrasonically for 50 minutes to obtain modified COPNA resin;

The preparation of COPNA resin includes the following steps: in a nitrogen environment, add 2g of bamboo tar and 2g of terephthalol, add 6.2% mass fraction of p-toluenesulfonic acid, react at 140°C until filament winding occurs, stop heating, and discharge Cool to obtain COPNA resin;

S2: Using a micro-gravure roller coating process, the prepared glucose-derived C@porous Al(OH) ₃ coaxial nanotube coating slurry is coated on both sides of the 9 μm base film by a coater on one side in a step-by-step manner. The coating thickness is 3 μm, and it is baked at 68°C and then rolled up to obtain a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes.

Example 6

A method for preparing a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes, including the following steps:

S1: Premix the dispersant and glucose-derived C@porous Al(OH) ₃ coaxial nanotubes in ultrapure water for 90 min at a rotation speed of 100 rpm; add the thickener and continue stirring for 90 min at a rotation speed of 350 rpm; add the binder and continue stirring 120min, rotating speed is 350rpm; add wetting agent and stir for 90min, rotating speed is 400rpm; filter and remove iron to obtain glucose-derived C@porous Al(OH) ₃ coaxial nanotube coating slurry;

A lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes includes a base film and a coating layer coated on the surface of the base film; in terms of parts by mass, the content of each component in the coating layer is: 0.8% Dispersant, 23% glucose-derived C@porous Al(OH) ₃ coaxial nanotubes, 0.85% thickener, 1.3% binder, 0.4% wetting agent, the balance is deionized water;

The base film is a polyethylene separator; the dispersant is hydrolyzed polymaleic anhydride, the thickener is sodium carboxymethylcellulose, the binder is COPNA resin, and the wetting agent is a silanol nonionic surfactant;

The preparation of glucose-derived C nanotubes includes the following steps:

Add 92 mg of hydrophilic treated silica nanowires to a glucose solution containing 101.4 mmol glucose under constant stirring, continue magnetic stirring for 50 min, and then conduct ultrasonic dispersion for 6 h, and transfer to a PTFE-lined stainless steel autoclave. in, and heated at 100°C for 5 hours, naturally cooled to 25°C, filtered, washed with absolute ethanol and deionized water, and dried at 80°C for 20 hours with a vacuum of 0.08Mpa to obtain carbon-coated silica nanowires. Coaxial composite material; add the carbon-coated silica nanowire coaxial composite material to 5.0 mol/L sodium hydroxide solution and keep it for 6 hours, then filter, wash and dry at 80°C for 10 hours. After drying, glucose is obtained Derivatized C nanotubes;

The preparation of glucose-derived C@porous Al(OH) ₃ coaxial nanotubes includes the following steps: magnetically stir 1.97g glucose-derived C nanotubes and 215 mL of ultrapure water for 90 min, then perform ultrasonic dispersion for 200 min, add 13.46 g of aluminum sulfate, Continue to stir 26.59g of urea until dissolved, raise the temperature to 95°C and react for 12 hours. Filter, wash with ultrapure water, and dry in a vacuum at 80°C for 32 hours. After drying, increase the temperature from 25°C to 120°C at a rate of 2°C/min. Keep the temperature constant for 155 minutes and cool to obtain glucose-derived C@porous Al(OH) ₃ coaxial nanotubes;

The preparation of hydrophilic treated silica nanowires includes the following steps: mix and stir 0.16g cetyltrimethylammonium bromide, 30mL absolute ethanol, and 70mL deionized water, add 9 μL ammonia solution, 0.1g normal Ethyl silicate, add 6% mass fraction of (3-mercaptopropyl)trimethoxysilane, immerse the indium tin oxide coated substrate, let stand at 58°C for 28h, wash, age at 100°C, use 0.15mol /L hydrochloric acid ethanol solution, and then treated with hydrogen peroxide solution to obtain sulfonated silica deposited on the indium tin oxide coating substrate, which is removed, dried and ground to obtain hydrophilic treated silica nanowires;

The binder is modified COPNA resin, and the preparation includes the following steps:

(1) In a nitrogen environment, react 0.2 mol of itaconic acid, 320 mL of deionized water, and 0.2 mol of 1,6-hexanediamine at 60°C for 20 minutes to obtain an itaconic acid mixture;

(2) Mix 80 mL of deionized water, 36 mL of absolute ethanol, 9 mL of acetonitrile, 9 mL of triethylamine, and 5 mL of tetraethylammonium hydroxide in a 56°C constant temperature water bath; add 221 mL of 3-aminopropyltriethoxysilane , reflux at 56°C for 20 hours, distill and concentrate under reduced pressure, add the concentrated solution to petroleum ether, let stand, filter under reduced pressure, wash with acetone 5 times, and obtain octaaminopropyl cage silsesquioxane after vacuum drying ;

(3) Mix and stir a mixture of 0.24 mol DOPO and 0.2 mol itaconic acid, raise the temperature to 88°C and react for 2.5 hours; filter with suction while hot, cool to 25°C, transfer to an ice water bath to cool for 9 hours, and filter with suction to obtain water-soluble resist. Fuel agent; add 2g of octaaminopropyl cage silsesquioxane and 10g of COPNA resin and stir ultrasonically for 60 minutes to obtain modified COPNA resin;

The preparation of COPNA resin includes the following steps: in a nitrogen environment, add 2g of bamboo tar and 2g of terephthalol, add 6.8% mass fraction of p-toluenesulfonic acid, react at 150°C until filament winding occurs, stop heating, and discharge Cool to obtain COPNA resin;

S2: Using a micro-gravure roller coating process, the prepared glucose-derived C@porous Al(OH) ₃ coaxial nanotube coating slurry is coated on both sides of the 9 μm base film by a coater on one side in a step-by-step manner. The coating thickness is 3 μm, and it is baked at 70°C and then rolled up to obtain a lithium-ion battery separator based on aluminum hydroxide coaxial nanotubes.

Comparative example 1

The same polyethylene film as in Examples 1-6, other processes are normal.

Comparative example 2

Taking Example 3 as the control group, porous Al(OH) ₃ nanotubes were used to replace the glucose-derived C@porous Al(OH) ₃ coaxial nanotubes, and other processes were normal.

Comparative example 3

Taking Example 3 as the control group, glucose-derived C was used to replace glucose-derived C@porous Al(OH) ₃ coaxial nanotubes, and other processes were normal.

Comparative example 4

Taking Example 3 as the control group, the hydrophilic treated silica was replaced with silica, and other processes were normal.

Comparative example 5

Taking Example 6 as the control group, no octaaminopropyl cage silsesquioxane was added, and other processes were normal.

Comparative example 6

Taking Example 6 as the control group, no glucose-derived C@porous Al(OH) ₃ coaxial nanotubes were added, and other processes were normal.

Performance test: Perform a performance test on the separators prepared in Examples 1-6 and Comparative Examples 1-6. Refer to GB/T36363-2018 for thickness, air permeability, acupuncture strength, ionic conductivity, and heat shrinkage tests;

Oxygen index measurement: Refer to IOS4589-2: The oxygen-nitrogen mixed gas is in a transparent combustion tube, the temperature of the mixed gas is 24°C, put the diaphragm in; when the top surface is ignited, the flame contacts the top surface for 25 seconds, remove it every 5 seconds, and observe Whether the diaphragm burns, the minimum oxygen concentration required to maintain combustion is the oxygen index;

Liquid absorption rate measurement: Cut a 50mm × 50mm sample from the prepared diaphragm, place the sample in a desiccator for 24 hours, take it out, weigh the sample, and record it as M (accurate to 0.01g); immerse the sample Place it in a beaker containing electrolyte, hold it for 10 minutes, gently clamp a corner of the sample with plastic tweezers, take it out and weigh it immediately, record it as M1 (accurate to 0.01g); liquid absorption rate = (M1-M) /M;

Determination of liquid retention rate: Cut a 50mm × 50mm sample from the prepared separator, place the sample in a desiccator for 24 hours, take it out, weigh the sample, and record it as M (accurate to 0.01g); immerse the sample Place in the beaker containing the electrolyte, hold it for 10 minutes, gently clamp one corner of the sample with plastic tweezers, take it out and hang it for 3 minutes until part of the electrolyte drops naturally, then weigh it and record it as M2 (accurate to 0.01g); Liquid retention rate = (M2-M)/M; that is, the results are shown in Table 1;

Table 1

Comparing Example 3 with Comparative Example 1, Comparative Example 2, and Comparative Example 3, it can be seen that the introduction of glucose-derived C@porous Al(OH) ₃ coaxial nanotubes greatly improves the mechanical strength and heat shrinkage performance of the separator; The introduction of glucose-derived C nanotubes on the one hand increases the mechanical properties of the separator, and on the other hand enhances the conductive properties of the separator, which is beneficial to enhancing the rapid transmission of lithium ions; in addition, the glucose-derived C@porous Al(OH) ₃ The shaft nanotube has a hollow structure as a whole, and the outer coating of Al(OH) ₃ has a porous structure, which further improves the lithium ion conductivity and greatly increases the specific surface area of the material, thereby greatly enhancing the liquid absorption and retention properties of the separator. liquid capacity;

Comparing Example 3 with Comparative Example 4, it can be seen that the sulfonic acid group is loaded on the vertical mesoporous silica channels in situ through the co-condensation method without changing the pore structure. The selectivity of the nanochannel is mainly determined by the size. Caused by the effect and charge effect, when the nanochannel is completely occupied by the electric double layer, the selective permeability is optimal. The present invention effectively improves the ionic conductivity of the membrane by limiting the preparation and introduction of hydrophilic treated silica nanowires. ;

Comparing Example 6 with Comparative Example 5, it can be seen that COPNA resin is synthesized using bamboo as a renewable raw material, bamboo tar as the raw material, terephthalic alcohol as the cross-linking agent, and p-toluenesulfonic acid as the catalyst. In an acidic environment, Paraphenylene glycol will produce activated carbocation ions, which will undergo electrophilic substitution reactions with the benzene rings in a large number of phenols and their derivatives in bamboo tar. The alcoholic hydroxyl groups in the generated products will be dehydrated under the action of acid to generate carbocation ions again. , the carbocation then reacts with aromatic hydrocarbons to form cross-linked macromolecules. As the degree of cross-linking deepens, the viscosity of the system increases, water vapor no longer escapes, and cross-links into a network structure to obtain COPNA resin. By controlling p-toluene The addition of sulfonic acid improves the softening point and heat resistance of the COPNA resin, the pretreatment process is simple, low-cost, and reduces waste emissions; it effectively increases the complexity of the macromolecular cross-linked network in the separator, and the COPNA resin It has excellent affinity with carbon materials, effectively improves the affinity between glucose-derived C@porous Al(OH) ₃ coaxial nanotubes and the separator, and effectively extends the service life of the separator;

The binder is modified to effectively improve the binding force between glucose-derived C@porous Al(OH) ₃ coaxial nanotubes, thickeners, binders, and wetting agents, and effectively improve the thermal shrinkage of the separator. , flame retardancy and ionic conductivity;

Comparing Example 6 with Example 3, Comparative Example 5, and Comparative Example 6, it can be seen that by introducing DOPO and its derivatives, octaaminopropyl cage silsesquioxane, and glucose-derived C@porous Al(OH) ₃ Coaxial nanotubes are compounded with multiple flame retardant elements to achieve synergistic flame retardancy; the three are used synergistically for the flame retardancy of the separator, and the silica particles produced by the decomposition of cage silsesquioxane are used to enhance DOPO and its derivatives, The quality and strength of the carbon layer formed by Al(OH) ₃ catalysis can form a stable ceramic layer containing a composite of silica and alumina, enhancing the stability of the carbon layer, blocking external heat flow and oxygen from the internal materials and flammability The contact of gas prevents the combustion reaction from proceeding, and synergistically greatly improves the flame retardant performance of the separator; and the introduction of a large number of active sites is conducive to improving the ion exchange capacity of the separator and effectively improving the safety of the separator.

In summary, the separator prepared by the present invention has good application prospects in the field of separators.

The above are only examples of the present invention, and do not limit the patent scope of the present invention. Under the inventive concept of the present invention, equivalent structural transformations made by using the description of the present invention, or directly/indirectly applied in other related All technical fields are included in the patent protection scope of the present invention.

Claims (9)

1. The lithium ion battery diaphragm based on the aluminum hydroxide coaxial nano tube is characterized by comprising a base film and a coating layer formed on the surface of the base film; the coating comprises the following components in parts by weight: 0.35 to 0.8 percent of dispersing agent and 9 to 23 percent of glucose derivative C@ porous Al (OH) ₃ Coaxial nano tube, 0.2% -0.85% of thickener, 0.6% -1.3% of binder, 0.1% -0.4% of wetting agent and the balance of deionized water;

glucose derived C@ porous Al (OH) ₃ The preparation of the coaxial nanotube comprises the following steps: magnetically stirring glucose derived C nanotube and ultrapure water for 80-90min, then performing ultrasonic dispersion for 190-200min, adding aluminum sulfate and urea, continuously stirring until dissolving, heating to 90-95C for reacting for 12-15h, performing suction filtration, washing with ultrapure water, vacuum drying at 75-80deg.C for 32-36h, drying, heating to 115-120deg.C at a heating rate of 2deg.C/min from 18-25deg.C, maintaining the temperature for 150-155min, and cooling to obtain glucose derived C@ porous Al (OH) ₃ Coaxial nanotubes.

2. The aluminum hydroxide coaxial nanotube based lithium ion battery separator of claim 1, wherein the base film is a polyolefin separator; the dispersing agent is a hydrolyzed polymaleic anhydride dispersing agent, the thickening agent is a sodium hydroxymethyl cellulose dispersing agent, the binder is a COPNA resin binder, and the wetting agent is a silanol nonionic surfactant.

3. The lithium ion battery separator based on aluminum hydroxide coaxial nanotubes according to claim 1, wherein the preparation of glucose derived C nanotubes comprises the steps of:

1) Mixing and stirring cetyl trimethyl ammonium bromide, absolute ethyl alcohol and deionized water, adding ammonia water solution and tetraethoxysilane, adding (3-mercaptopropyl) trimethoxysilane, immersing an indium tin oxide coated substrate, standing at 55-58 ℃ for 28h, washing, aging at 100 ℃, washing with 0.15mol/L ethanol solution of hydrochloric acid, treating with hydrogen peroxide solution to obtain sulfonated silicon dioxide deposited on the indium tin oxide coated substrate, taking down, drying and grinding to obtain a silicon dioxide nanowire after hydrophilic treatment;

2) Adding the silicon dioxide nanowire subjected to hydrophilic treatment into a glucose solution under the condition of continuous stirring, continuing to magnetically stir for 40-50min, then performing ultrasonic dispersion for 6-7h, transferring into a stainless steel autoclave with a PTFE lining, heating for 5-6h at 95-100 ℃, naturally cooling to 18-25 ℃, filtering, washing with absolute ethyl alcohol and deionized water, drying at 70-80 ℃ for 20-24h, and vacuum degree being 0.08Mpa to obtain the carbon-coated silicon dioxide nanowire coaxial composite material; adding the carbon-coated silicon dioxide nanowire coaxial composite material into 5.0mol/L sodium hydroxide solution, maintaining for 5-6h, filtering, washing, drying at 70-80 ℃ for 10-12h, and drying to obtain the glucose-derived C nanotube.

4. The aluminum hydroxide coaxial nanotube based lithium ion battery separator of claim 3 wherein the preparation of the hydrophilically treated silica nanowires comprises the steps of: the mass molar ratio of the silicon dioxide nanowire after hydrophilic treatment to glucose in the glucose solution is 92 mg/101.4 mmol.

5. The aluminum hydroxide coaxial nanotube based lithium ion battery separator of claim 1 wherein the porous Al (OH) is derived from glucose C@ ₃ In the preparation of the coaxial nano tube, the mass ratio of the glucose derived C nano tube to the aluminum sulfate to the urea is 1.97:13.46:26.59.

6. The preparation method of the lithium ion battery diaphragm based on the aluminum hydroxide coaxial nano tube is characterized by comprising the following steps:

s1: dispersing agent, glucose derived C@ porous Al (OH) ₃ Premixing the coaxial nanotubes in ultrapure water for 10-90min, wherein the rotating speed is 100-600rpm; adding thickener, stirring for 10-90min at 350-900rpm;adding binder, and stirring for 40-120min at 350-700rpm; adding wetting agent, stirring for 30-90min at 400-900rpm; filtering to remove iron to obtain glucose derivative C@ porous Al (OH) ₃ Coating slurry on the coaxial nano tube;

S2: the prepared glucose is derived from C@ porous Al (OH) by adopting a micro-gravure roller coating process ₃ The coaxial nanotube coating slurry is coated on two sides of a base film step by step, baked at 65-70 ℃ and then rolled, and the lithium ion battery diaphragm based on the aluminum hydroxide coaxial nanotube is obtained.

7. The method for preparing a lithium ion battery separator based on aluminum hydroxide coaxial nanotubes according to claim 6, wherein the binder is modified COPNA resin, and the preparation method comprises the following steps:

(1) In a nitrogen environment, itaconic acid, deionized water and 1, 6-hexamethylenediamine are reacted for 20-30min at 55-60 ℃ to obtain itaconic acid mixed solution;

(2) Mixing deionized water, absolute ethyl alcohol, acetonitrile, triethylamine and tetraethylammonium hydroxide in a constant-temperature water bath at 52-56 ℃; adding 3-aminopropyl triethoxysilane, refluxing at 52-56 ℃ for 20-22h, distilling under reduced pressure for concentration, adding the concentrated solution into petroleum ether, standing, vacuum filtering, washing with acetone for 2-5 times, and vacuum drying to obtain octaaminopropyl cage-type silsesquioxane;

(3) Mixing and stirring DOPO and itaconic acid mixed solution, heating to 85-88 ℃ and reacting for 2.5-3h; filtering while the mixture is hot, cooling the mixture to 18-25 ℃, transferring the mixture to ice water bath for cooling for 9-11h, and filtering the mixture to obtain the water-soluble flame retardant; adding the octaaminopropyl cage-type silsesquioxane and the COPNA resin, and carrying out ultrasonic stirring for 30-60min to obtain the modified COPNA resin.

8. The method for preparing the lithium ion battery diaphragm based on the aluminum hydroxide coaxial nano tube according to claim 7, wherein the molar volume ratio of itaconic acid, 1, 6-hexamethylenediamine and deionized water is 0.2mol:0.2mol:320mL; the volume ratio of deionized water, absolute ethyl alcohol, acetonitrile, triethylamine and tetraethylammonium hydroxide is 80mL:36mL:9 mL:5mL; the molar ratio of DOPO to itaconic acid was 1.2:1.

9. The method for preparing a lithium ion battery separator based on aluminum hydroxide coaxial nanotubes according to claim 7, wherein the preparation of COPNA resin comprises the following steps: under the nitrogen environment, the bamboo tar and the terephthalyl alcohol are weighed according to the mass ratio of 1:1, the p-toluenesulfonic acid with the mass fraction of 5.4-6.8% is added, the reaction is carried out at 130-150 ℃ until the phenomenon of filament winding occurs, the heating is stopped, and the material is discharged and cooled, thus obtaining the COPNA resin.