High-temperature-resistant acrylic diaphragm adhesive and preparation method thereof

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to high-temperature-resistant acrylic diaphragm glue and a preparation method thereof. The high-temperature-resistant acrylic diaphragm adhesive comprises a base film and high-temperature-resistant acrylic slurry coated on two sides of the base film, wherein the base film is a polyolefin film; the high-temperature-resistant acrylic slurry is prepared from the following raw materials in parts by mass: 50 to 100 parts of n-butyl acrylate, 1 to 10 parts of acrylic acid-2-hydroxyethyl ester, 50 to 100 parts of nanoscale ceramic powder, 50 to 80 parts of urea, 5 to 15 parts of graphene oxide, 1 to 4 parts of a first cross-linking agent, 1 to 2 parts of a second cross-linking agent, 0.01 to 0.1 part of an initiator, 5 to 15 parts of polyvinylidene fluoride, 5 to 15 parts of aluminum hydroxide and 50 to 65 parts of polysiloxane. The ceramic slurry has the characteristics of low shrinkage rate and high safety at high temperature and high conductivity at normal temperature, can bear the high temperature of 180-200 DEG C, and is beneficial to the cycling stability of an electrode.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion batteries, and in particular to a high temperature resistant acrylic diaphragm adhesive and a preparation method thereof. Background Art

[0002] Lithium-ion batteries are widely used in power, consumption and energy storage due to their advantages such as high specific energy, high specific power, high voltage platform, low self-discharge, long cycle life, low environmental pollution and no memory effect.

[0003] The battery separator separates the positive and negative electrodes in the lithium battery, and absorbs the electrolyte to allow lithium ions to pass through. However, with the continuous development of electric vehicles, the requirements for the safety, charge and discharge performance, cycle performance and rate capability of lithium batteries are getting higher and higher. In order to improve the surface properties of the separator, a layer of ceramic slurry is currently coated on the surface of the separator. Ceramic coated separator is currently the most effective way to improve the safety of lithium batteries. After the separator is coated with ceramic slurry, it can effectively improve the heat shrinkage resistance, safety, thermal stability of the separator, and improve the mechanical strength of the separator, thereby extending the service life of the separator.

[0004] As an important key material, the performance of the ceramic diaphragm of lithium-ion batteries determines the interface structure and internal resistance of the battery, directly affecting the battery's capacity, cycle and safety performance. Diaphragms with excellent performance are important for improving the overall performance of the battery. Polyolefin diaphragms are widely used in lithium batteries due to their high chemical stability. However, polyolefin diaphragms have poor heat resistance. Ceramic coating can improve their heat resistance to a certain extent, but when the temperature rises to above 150°C, the diaphragm is prone to breakage. At the same time, the ceramic coating increases the internal resistance of the diaphragm, which brings resistance to the ion conduction of the battery cycle, which needs to be solved urgently. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a high temperature resistant acrylic diaphragm adhesive and a preparation method thereof.

[0006] A high-temperature resistant acrylic diaphragm adhesive comprises: a base film and a high-temperature resistant acrylic slurry coated on both sides of the base film; wherein the base film is a polyolefin film; the raw materials of the high-temperature resistant acrylic slurry comprise, by mass, 50-100 parts of n-butyl acrylate, 1-10 parts of 2-hydroxyethyl acrylate, 50-100 parts of nano-grade ceramic powder, 50-80 parts of urea, 5-15 parts of graphene oxide, 1-4 parts of a first cross-linking agent, 1-2 parts of a second cross-linking agent, 0.01-0.1 parts of an initiator, 5-15 parts of polyvinylidene fluoride, 5-15 parts of aluminum hydroxide, and 50-65 parts of polysiloxane.

[0007] Preferably, the base film is a polypropylene film with a thickness of 10-20 μm and a porosity of 35-45%.

[0008] Preferably, the first crosslinking agent includes: glutaraldehyde and resorcinol.

[0009] More preferably, the mass ratio of glutaraldehyde to resorcinol is 4 - 8:2 - 5.

[0010] Preferably, the second crosslinking agent is benzylidene diisocyanate.

[0011] Preferably, the initiator is a peroxide initiator, preferably at least one of benzoyl peroxide, tert-butyl peroxybenzoate, and methyl ethyl ketone peroxide.

[0012] Preferably, the polysiloxane is at least one of polydimethylsiloxane, cyclomethylsiloxane, aminosiloxane, and polymethylphenylsiloxane.

[0013] Preferably, the high-temperature resistant acrylic sizing agent is prepared by the following steps: S1. Add nano-ceramic powder to an ethanol aqueous solution, ultrasonically treat for 1 - 2 h, add 50 - 80 parts of urea, ball mill for 10 - 20 h, filter, wash, and vacuum dry to obtain amino-functionalized ceramic. S2. Add the amino-functionalized ceramic and graphene oxide to water, stir for 1 - 2 h, add the first crosslinking agent thereto, stir at 60 - 80 °C for 2 - 5 h, directionally freeze for 1 - 3 h, and freeze-dry to obtain pretreated nano-ceramic powder. S3. Mix n-butyl acrylate, 2-hydroxyethyl acrylate, and the second crosslinking agent, stir at 70 - 90 °C for 1 - 2 h, add the pretreated nano-ceramic powder, initiator, and dimethylacetamide thereto, continue to stir for 1 - 3 h, cool down to 50 - 60 °C, add polyvinylidene fluoride, aluminum hydroxide, and polysiloxane thereto, stir for 10 - 30 min, and cool to room temperature.

[0014] More preferably, in S2, during the directional freezing process, the cold source is at the bottom, and the freezing temperature is -30 to -50 °C.

[0015] The preparation method of the above-mentioned high-temperature resistant acrylic separator adhesive includes the following steps: Coat the high-temperature resistant acrylic sizing agent on both sides of the base film, cure at 50 - 80 °C for 5 - 10 min, dry, place it in an aqueous solution containing ammonia water and vitamin C, perform reduction treatment at 120 - 140 °C for 2 - 4 h, dry, and the obtained coating thickness is 2 - 6 μm.

[0016] Preferably, in the above-mentioned aqueous solution containing ammonia water and vitamin C, the ammonia concentration is 12 - 18%, and the vitamin C concentration is 0.5 - 1 g / mL.

[0017] Beneficial effects: In the present invention, urea is used as the ammonia source to blend and modify nanoscale ceramic powders, thereby modifying amino groups into the ceramic structure. After being compounded with graphene oxide and cross-linked, graphene oxide and ceramic powders are tightly combined with extremely high stability. Subsequently, a regular aerogel structure is formed through directional freezing, which not only has a higher thermal conductivity and better high-temperature stability, but also has excellent dispersion and compatibility with acrylic resin, and can significantly enhance the high-temperature strength of acrylic resin. At the same time, the directional and regular graphene oxide sheet structure forms an ion conduction path, effectively improving the ion conduction performance.

[0018] The present invention not only has the characteristics of low shrinkage rate and high safety of ceramic slurry at high temperatures, but also has the characteristic of high conductivity at room temperature. It can not only greatly improve the charging speed of lithium-ion batteries and increase the specific energy of the batteries, but also form a good network structure between ceramic particles and acrylic resin, which can withstand high temperatures of 180 - 200 °C, effectively solving the problem of shrinkage or melting of the separator caused by high temperature. At the same time, using this network structure can effectively prevent the movement of nanoparticles during the cycle, maintaining the stability of the electrode structure and being beneficial to the cycle stability of the electrode.

[0019] The present invention provides a relatively efficient process, in which the coating method is simple, the cost is low, and the performance is stable. When it is applied to lithium-ion batteries used in electric vehicles, it can withstand higher temperatures, and the shrinkage rate of the separator is significantly lower than that of the existing ceramic-coated separators, being suitable for large-scale popularization and application. Description of the Drawings

[0020] Figure 1 It is a comparison chart of the tensile strength of the products obtained in Examples 1 - 5 and Comparative Examples 1 - 3.

[0021] Figure 2 It is a comparison chart of the thermal shrinkage rate of the products obtained in Examples 1 - 5 and Comparative Examples 1 - 3.

[0022] Figure 3 It is a comparison chart of the liquid absorption rate and ion conductivity of the products obtained in Examples 1 - 5 and Comparative Examples 1 - 3.

[0023] Figure 4 It is a comparison chart of the capacity retention rate of button batteries prepared from the products obtained in Examples 1 - 5 and Comparative Examples 1 - 3. Detailed Embodiments

[0024] The present invention will be further explained below in conjunction with specific embodiments.

[0025] The polypropylene film is purchased from a certain new material company in Wenzhou, with a thickness of 16 μm and a porosity of 40%. The nanoscale ceramic powder is purchased from a certain new material company in Hangzhou, with a composition of alumina, an average particle size of 0.5 μm, and a purity of 99.9%.

[0026] Example 1: A high-temperature resistant acrylic separator adhesive, comprising: a polypropylene film and a high-temperature resistant acrylic slurry coated on both sides of the polypropylene film.

[0027] The raw materials of the high-temperature resistant acrylic slurry include: 50 g of n-butyl acrylate, 1 g of 2-hydroxyethyl acrylate, 50 g of nanoscale ceramic powder, 50 g of urea, 5 g of graphene oxide, 1 g of a first crosslinking agent, 1 g of xylylene diisocyanate, 0.01 g of tert-butyl peroxybenzoate, 5 g of polyvinylidene fluoride, 5 g of aluminum hydroxide, and 50 g of cyclomethicone.

[0028] The first crosslinking agent is composed of glutaraldehyde and resorcinol in a mass ratio of 4:2.

[0029] The above high-temperature resistant acrylic slurry is prepared by the following steps: S1. Add the nanoscale ceramic powder to 100 g of an ethanol aqueous solution with a mass fraction of 40% and ultrasonically treat for 1 h at an ultrasonic frequency of 5 kHz. Add urea and send it into a planetary ball mill for ball milling for 10 h, where the revolution speed is 500 r / min and the rotation speed is 200 r / min. Filter, wash, and vacuum dry to obtain amino-functionalized ceramics; S2. Add the amino-functionalized ceramics and graphene oxide to 200 g of water and stir at a speed of 1000 r / min for 1 h. Add the first crosslinking agent thereto and stir at 60 °C for 2 h, and then directionally freeze for 1 h (the cold source is at the bottom and the freezing temperature is -30 °C). Freeze-dry to obtain pretreated nanoscale ceramic powder; S3. Mix n-butyl acrylate, 2-hydroxyethyl acrylate, and xylylene diisocyanate and stir at 70 °C for 1 h. Add the pretreated nanoscale ceramic powder, tert-butyl peroxybenzoate, and 200 g of dimethylacetamide thereto and continue to stir for 1 h. Cool down to 50 °C, add polyvinylidene fluoride, aluminum hydroxide, and cyclomethicone thereto and stir for 10 min at a stirring speed of 1000 r / min, and then cool to room temperature.

[0030] The preparation method of the above high-temperature resistant acrylic separator adhesive includes the following steps: Coat the high-temperature resistant acrylic slurry on both sides of the base film, cure at 50 °C for 5 min, dry, place it in an aqueous solution containing ammonia water and vitamin C (ammonia concentration is 12%, vitamin C concentration is 0.5 g / mL), perform reduction treatment at 120 °C for 2 h, dry, and the obtained coating thickness is 2 μm.

[0031] Example 2: A high-temperature resistant acrylic separator adhesive, comprising: a polypropylene film and a high-temperature resistant acrylic slurry coated on both sides of the polypropylene film.

[0032] The raw materials of the high-temperature resistant acrylic slurry include: 100 g of n-butyl acrylate, 10 g of 2-hydroxyethyl acrylate, 100 g of nano-ceramic powder, 80 g of urea, 15 g of graphene oxide, 4 g of the first cross-linking agent, 2 g of xylylene diisocyanate, 0.1 g of methyl ethyl ketone peroxide, 15 g of polyvinylidene fluoride, 15 g of aluminum hydroxide, and 65 g of amino siloxane.

[0033] The first cross-linking agent is composed of glutaraldehyde and resorcinol in a mass ratio of 8:5.

[0034] The above high-temperature resistant acrylic slurry is prepared by the following steps: S1. Add the nano-ceramic powder to 150 g of an ethanol aqueous solution with a mass fraction of 60% and ultrasonically treat for 2 h at an ultrasonic frequency of 12 kHz. Add urea and send it into a planetary ball mill for ball milling for 20 h, where the revolution speed is 800 r / min and the rotation speed is 400 r / min. Filter, wash, and vacuum dry to obtain amino-functionalized ceramics; S2. Add the amino-functionalized ceramics and graphene oxide to 400 g of water and stir at a speed of 2000 r / min for 2 h. Add the first cross-linking agent thereto and stir at a temperature of 80 °C for 5 h. Perform directional freezing for 3 h (the cold source is at the bottom and the freezing temperature is -50 °C), and freeze-dry to obtain pre-treated nano-ceramic powder; S3. Mix n-butyl acrylate, 2-hydroxyethyl acrylate, and xylylene diisocyanate and stir at a temperature of 90 °C for 2 h. Add the pre-treated nano-ceramic powder, methyl ethyl ketone peroxide, and 400 g of dimethylacetamide thereto and continue stirring for 3 h. Cool down to 60 °C, add polyvinylidene fluoride, aluminum hydroxide, and amino siloxane and stir for 30 min at a stirring speed of 3000 r / min, and then cool to room temperature.

[0035] The preparation method of the above high-temperature resistant acrylic separator adhesive includes the following steps: Coat the high-temperature resistant acrylic slurry on both sides of the base film, cure at a temperature of 80 °C for 10 min, dry, place it in an aqueous solution containing ammonia water and vitamin C (ammonia concentration is 18%, vitamin C concentration is 1 g / mL), and perform reduction treatment at a temperature of 140 °C for 4 h, then dry. The thickness of the obtained coating is 6 μm.

[0036] Example 3: A high-temperature resistant acrylic separator adhesive, including: a polypropylene film and the high-temperature resistant acrylic slurry coated on both sides of the polypropylene film.

[0037] The raw materials of the high-temperature resistant acrylic paste include: 70 g of n-butyl acrylate, 7 g of 2-hydroxyethyl acrylate, 70 g of nano-ceramic powder, 70 g of urea, 8 g of graphene oxide, 3 g of the first cross-linking agent, 1.3 g of xylylene diisocyanate, 0.08 g of tert-butyl peroxybenzoate, 8 g of polyvinylidene fluoride, 12 g of aluminum hydroxide, and 55 g of polymethylphenylsiloxane.

[0038] The first cross-linking agent is composed of glutaraldehyde and resorcinol in a mass ratio of 7:3.

[0039] The above high-temperature resistant acrylic paste is prepared by the following steps: S1. Add the nano-ceramic powder to 130 g of an ethanol aqueous solution with a mass fraction of 45%, perform ultrasonic treatment for 100 min at an ultrasonic frequency of 6 kHz, add urea, and send it into a planetary ball mill for ball milling for 18 h, where the revolution speed is 600 r / min and the rotation speed is 340 r / min. Filter, wash, and vacuum dry to obtain amino-functionalized ceramics; S2. Add the amino-functionalized ceramics and graphene oxide to 250 g of water, stir at a speed of 1800 r / min for 80 min, add the first cross-linking agent thereto, stir at a temperature of 75 °C for 3 h, perform directional freezing for 2.5 h (the cold source is at the bottom and the freezing temperature is -30 °C), and freeze-dry to obtain pretreated nano-ceramic powder; S3. Mix n-butyl acrylate, 2-hydroxyethyl acrylate, and xylylene diisocyanate, stir at a temperature of 85 °C for 80 min, add the pretreated nano-ceramic powder, tert-butyl peroxybenzoate, and 360 g of dimethylacetamide thereto and continue stirring for 1.5 h. Cool down to 58 °C, add polyvinylidene fluoride, aluminum hydroxide, and polymethylphenylsiloxane thereto and stir for 10 min at a stirring speed of 2500 r / min, and cool down to room temperature.

[0040] The preparation method of the above high-temperature resistant acrylic separator adhesive includes the following steps: Coat the high-temperature resistant acrylic paste on both sides of the base film, cure at a temperature of 60 °C for 9 min, dry, place it in an aqueous solution containing ammonia water and vitamin C (ammonia concentration is 14%, vitamin C concentration is 0.9 g / mL), perform reduction treatment at a temperature of 125 °C for 3.5 h, dry, and the obtained coating thickness is 3 μm.

[0041] Example 4: A high-temperature resistant acrylic separator adhesive, comprising: a polypropylene film and the high-temperature resistant acrylic paste coated on both sides of the polypropylene film.

[0042] The raw materials of the high-temperature resistant acrylic slurry include: 90 g of n-butyl acrylate, 3 g of 2-hydroxyethyl acrylate, 90 g of nano-ceramic powder, 60 g of urea, 12 g of graphene oxide, 2 g of the first cross-linking agent, 1.7 g of xylylene diisocyanate, 0.02 g of benzoyl peroxide, 12 g of polyvinylidene fluoride, 8 g of aluminum hydroxide, and 60 g of polydimethylsiloxane.

[0043] The first cross-linking agent is composed of glutaraldehyde and resorcinol in a mass ratio of 5:4.

[0044] The above high-temperature resistant acrylic slurry is prepared by the following steps: S1. Add the nano-ceramic powder to 110 g of an ethanol aqueous solution with a mass fraction of 55%, perform ultrasonic treatment for 80 min at an ultrasonic frequency of 9 kHz, add urea, and send it into a planetary ball mill for ball milling for 12 h, where the revolution speed is 700 r / min and the rotation speed is 260 r / min. Filter, wash, and vacuum dry to obtain amino-functionalized ceramics; S2. Add the amino-functionalized ceramics and graphene oxide to 350 g of water, stir at a speed of 1200 r / min for 100 min, add the first cross-linking agent thereto, stir at a temperature of 65 °C for 4 h, perform directional freezing for 1.5 h (the cold source is at the bottom and the freezing temperature is -50 °C), and freeze-dry to obtain pre-treated nano-ceramic powder; S3. Mix n-butyl acrylate, 2-hydroxyethyl acrylate, and xylylene diisocyanate, stir at a temperature of 75 °C for 100 min, add the pre-treated nano-ceramic powder, benzoyl peroxide, and 240 g of dimethylacetamide thereto and continue stirring for 2.5 h, cool down to 52 °C, add polyvinylidene fluoride, aluminum hydroxide, and polydimethylsiloxane thereto and stir for 30 min at a stirring speed of 1500 r / min, and cool down to room temperature.

[0045] The preparation method of the above high-temperature resistant acrylic separator adhesive includes the following steps: Coat the high-temperature resistant acrylic slurry on both sides of the base film, cure at a temperature of 70 °C for 7 min, dry, place it in an aqueous solution containing ammonia water and vitamin C (ammonia concentration is 16% and vitamin C concentration is 0.7 g / mL), perform reduction treatment at a temperature of 135 °C for 2.5 h, dry, and the obtained coating thickness is 5 μm.

[0046] Example 5: A high-temperature resistant acrylic separator adhesive, including: a polypropylene film and the high-temperature resistant acrylic slurry coated on both sides of the polypropylene film.

[0047] The raw materials of the high-temperature resistant acrylic paste include: 80 g of n-butyl acrylate, 5 g of 2-hydroxyethyl acrylate, 80 g of nano-ceramic powder, 65 g of urea, 10 g of graphene oxide, 2.5 g of a first cross-linking agent, 1.5 g of xylylene diisocyanate, 0.05 g of benzoyl peroxide, 10 g of polyvinylidene fluoride, 10 g of aluminum hydroxide, and 58 g of polydimethylsiloxane.

[0048] The first cross-linking agent is composed of glutaraldehyde and resorcinol in a mass ratio of 6:3.5.

[0049] The above high-temperature resistant acrylic paste is prepared by the following steps: S1. Add the nano-ceramic powder to 120 g of an ethanol aqueous solution with a mass fraction of 50%, perform ultrasonic treatment for 90 min at an ultrasonic frequency of 7.5 kHz, add urea, and send it into a planetary ball mill for ball milling for 15 h, where the revolution speed is 650 r / min and the rotation speed is 300 r / min. Filter, wash, and vacuum dry to obtain amino-functionalized ceramics; S2. Add the amino-functionalized ceramics and graphene oxide to 300 g of water, stir at a speed of 1500 r / min for 90 min, add the first cross-linking agent thereto, stir at a temperature of 70 °C for 3.5 h, perform directional freezing for 2 h (the cold source is at the bottom and the freezing temperature is -40 °C), and freeze-dry to obtain pretreated nano-ceramic powder; S3. Mix n-butyl acrylate, 2-hydroxyethyl acrylate, and xylylene diisocyanate, stir at a temperature of 80 °C for 90 min, add the pretreated nano-ceramic powder, benzoyl peroxide, and 300 g of dimethylacetamide thereto and continue stirring for 2 h, cool down to 55 °C, add polyvinylidene fluoride, aluminum hydroxide, and polydimethylsiloxane thereto and stir for 20 min at a stirring speed of 2000 r / min, and cool to room temperature.

[0050] The preparation method of the above high-temperature resistant acrylic separator adhesive includes the following steps: Coat the high-temperature resistant acrylic paste on both sides of the base film, cure at a temperature of 65 °C for 8 min, dry, place it in an aqueous solution containing ammonia water and vitamin C (ammonia concentration is 15%, vitamin C concentration is 0.8 g / mL), perform reduction treatment at a temperature of 130 °C for 3 h, dry, and the obtained coating thickness is 4 μm.

[0051] Comparative Example 1: A high-temperature resistant acrylic separator adhesive, including: a polypropylene film and the high-temperature resistant acrylic paste coated on both sides of the polypropylene film.

[0052] The raw materials of the high-temperature resistant acrylic slurry include: 80 g of n-butyl acrylate, 5 g of 2-hydroxyethyl acrylate, 80 g of nano-ceramic powder, 10 g of graphene oxide, 2.5 g of the first cross-linking agent, 1.5 g of xylylene diisocyanate, 0.05 g of benzoyl peroxide, 10 g of polyvinylidene fluoride, 10 g of aluminum hydroxide, and 58 g of polydimethylsiloxane.

[0053] The first cross-linking agent is composed of glutaraldehyde and resorcinol in a mass ratio of 6:3.5.

[0054] The above high-temperature resistant acrylic slurry is prepared by the following steps: S1. Add the nano-ceramic powder and graphene oxide to 300 g of water, stir at a speed of 1500 r / min for 90 min, add the first cross-linking agent thereto, stir at a temperature of 70 °C for 3.5 h, and perform directional freezing for 2 h (the cold source is at the bottom and the freezing temperature is -40 °C), and then freeze-dry to obtain the pretreated nano-ceramic powder; S2. Mix n-butyl acrylate, 2-hydroxyethyl acrylate, and xylylene diisocyanate, stir at a temperature of 80 °C for 90 min, add the pretreated nano-ceramic powder, benzoyl peroxide, and 300 g of dimethylacetamide thereto and continue stirring for 2 h, cool down to 55 °C, add polyvinylidene fluoride, aluminum hydroxide, and polydimethylsiloxane thereto and stir for 20 min, with the stirring speed being 2000 r / min, and then cool down to room temperature.

[0055] The preparation method of the above high-temperature resistant acrylic separator adhesive includes the following steps: Coat the high-temperature resistant acrylic slurry on both sides of the base film, cure at a temperature of 65 °C for 8 min, dry, place it in an aqueous solution containing ammonia water and vitamin C (the ammonia concentration is 15% and the vitamin C concentration is 0.8 g / mL), perform reduction treatment at a temperature of 130 °C for 3 h, dry, and the obtained coating thickness is 4 μm.

[0056] Comparative Example 2: A high-temperature resistant acrylic separator adhesive, including: a polypropylene film and the high-temperature resistant acrylic slurry coated on both sides of the polypropylene film.

[0057] The raw materials of the high-temperature resistant acrylic slurry include: 80 g of n-butyl acrylate, 5 g of 2-hydroxyethyl acrylate, 80 g of nano-ceramic powder, 65 g of urea, 10 g of graphene oxide, 2.5 g of the first cross-linking agent, 1.5 g of xylylene diisocyanate, 0.05 g of benzoyl peroxide, 10 g of polyvinylidene fluoride, 10 g of aluminum hydroxide, and 58 g of polydimethylsiloxane.

[0058] The first cross-linking agent is composed of glutaraldehyde and resorcinol in a mass ratio of 6:3.5.

[0059] The above high-temperature resistant acrylic slurry is prepared by the following steps: S1. Add nanoscale ceramic powder into 120 g of ethanol aqueous solution with a mass fraction of 50%, ultrasonically treat for 90 min with an ultrasonic frequency of 7.5 kHz, add urea, and send it into a planetary ball mill for ball milling for 15 h, where the revolution speed is 650 r / min and the rotation speed is 300 r / min, filter, wash, and vacuum dry to obtain amino-functionalized ceramic; S2. Add the amino-functionalized ceramic and graphene oxide into 300 g of water, stir at a speed of 1500 r / min for 90 min, add a first cross-linking agent thereto, stir at a temperature of 70 °C for 3.5 h, freeze at -40 °C for 2 h (the cold source is around), and freeze-dry to obtain pretreated nanoscale ceramic powder; S3. Mix n-butyl acrylate, 2-hydroxyethyl acrylate, and xylylene diisocyanate, stir at a temperature of 80 °C for 90 min, add the pretreated nanoscale ceramic powder, benzoyl peroxide, and 300 g of dimethylacetamide thereto and continue stirring for 2 h, cool down to 55 °C, add polyvinylidene fluoride, aluminum hydroxide, and polydimethylsiloxane and stir for 20 min with a stirring speed of 2000 r / min, and cool to room temperature.

[0060] The preparation method of the above high-temperature resistant acrylic separator adhesive comprises the following steps: Coat the high-temperature resistant acrylic slurry on both sides of the base film, cure at a temperature of 65 °C for 8 min, dry, place it in an aqueous solution containing ammonia water and vitamin C (ammonia concentration is 15%, vitamin C concentration is 0.8 g / mL), perform reduction treatment at a temperature of 130 °C for 3 h, dry, and the obtained coating thickness is 4 μm.

[0061] Comparative Example 3: A high-temperature resistant acrylic separator adhesive, comprising: a polypropylene film and a high-temperature resistant acrylic slurry coated on both sides of the polypropylene film.

[0062] The raw materials of the high-temperature resistant acrylic slurry include: 80 g of n-butyl acrylate, 5 g of 2-hydroxyethyl acrylate, 80 g of nanoscale ceramic powder, 10 g of graphene oxide, 1.5 g of xylylene diisocyanate, 0.05 g of benzoyl peroxide, 10 g of polyvinylidene fluoride, 10 g of aluminum hydroxide, and 58 g of polydimethylsiloxane.

[0063] The above high-temperature resistant acrylic slurry is prepared by the following steps: S1. Add the nanoscale ceramic powder and graphene oxide into 300 g of water, stir at a speed of 1500 r / min for 90 min, and freeze-dry to obtain pretreated nanoscale ceramic powder; S3. Mix n-butyl acrylate, 2-hydroxyethyl acrylate, and xylylene diisocyanate, stir at 80 °C for 90 min, add the pretreated nano-ceramic powder, benzoyl peroxide, and 300 g of dimethylacetamide thereto, continue stirring for 2 h, cool down to 55 °C, add polyvinylidene fluoride, aluminum hydroxide, and polydimethylsiloxane thereto, stir for 20 min, with the stirring speed being 2000 r / min, and then cool down to room temperature.

[0064] The preparation method of the above high-temperature resistant acrylic separator adhesive includes the following steps: Coat the high-temperature resistant acrylic slurry on both sides of the base film, cure at 65 °C for 8 min, dry, place it in an aqueous solution containing ammonia water and vitamin C (ammonia concentration is 15%, vitamin C concentration is 0.8 g / mL), perform reduction treatment at 130 °C for 3 h, dry, and the obtained coating thickness is 4 μm.

[0065] Cut the products obtained in Examples 1-5 and Comparative Examples 1-3 into 15 mm × 200 mm, stretch them under a constant tensile force on a tensile testing machine, with the stretching speed being 50 mm / min, until the separator breaks.

[0066] As Figure 1 shown, the tensile strength of the product obtained in Example 5 is the highest, superior to Comparative Example 1 and Comparative Example 3 (P < 0.05), but there is no significant difference compared with Examples 1-4 and Comparative Example 2 (P > 0.05).

[0067] Cut the products obtained in Examples 1-5 and Comparative Examples 1-3 into 100 mm × 100 mm, and then conduct a thermal shrinkage rate test. The thermal shrinkage test conditions are 200 °C × 1 h.

[0068] As Figure 2 shown, the thermal shrinkage rate of the product obtained in Example 5 is the lowest, superior to Comparative Examples 1-3 (P < 0.05), but there is no significant difference compared with Examples 1-4 (P > 0.05).

[0069] Conduct a separator electrolyte (EC:PC:EMC:EP = 1:1:1:1) absorption test on the products obtained in Examples 1-5 and Comparative Examples 1-3. The sample size is 50 mm × 100 mm, weigh it (denoted as M0), and weigh it again after soaking in the electrolyte for 24 h (denoted as M1).

[0070] Liquid absorption rate = (M1 - M0) ÷ M0 × 100%.

[0071] Use the products obtained in Examples 1-5 and Comparative Examples 1-3 to form button batteries with ternary positive electrode sheets and graphite negative electrode sheets respectively. Test the ionic conductivity at room temperature (25 °C) environment, with a frequency of 0 - 100000 Hz and a perturbation voltage of 5 mV.

[0072] AsFigure 3 As shown, the liquid absorption rate and ionic conductivity of the product obtained in Example 5 are the highest, superior to those of Comparative Examples 1-3 (P < 0.05), but there is no significant difference from those of Examples 1-4 (P > 0.05).

[0073] The discharge rate test of the above button battery was carried out as follows: the button battery was charged at a constant current and constant voltage to 4.35V at a current of 0.5C, and then charged at a constant voltage until the current dropped to 0.05C for cutoff. Then, it was discharged to 3.0V at currents of 0.2C, 1.0C, and 2.0C respectively, and the discharge capacities at different discharge rates were recorded. Taking the discharge capacity at 0.2C as 100%, the corresponding battery capacity retention rate was calculated.

[0074] As Figure 4 shown, the button battery prepared with the product obtained in Example 5 has the highest capacity retention rate, superior to those of Comparative Examples 1-3 (P < 0.05), but there is no significant difference from those of Examples 1-4 (P > 0.05).

[0075] The applicant believes that the reason for the above results is as follows: in the present invention, urea is used as the ammonia source to blend and modify the nano-ceramic powder, so that amino groups are modified into the ceramic structure. Then, after being compounded with graphene oxide and crosslinked, graphene oxide and ceramic powder are tightly combined with extremely high stability. Subsequently, a regular aerogel structure is formed by directional freezing, which not only has a higher thermal conductivity and better high-temperature stability, but also has excellent dispersion and compatibility with acrylic resin, and can significantly enhance the high-temperature strength of acrylic resin. At the same time, the directional and regular graphene oxide sheet structure forms an ion conduction path, effectively improving the ion conduction performance.

[0076] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitution or change, and should be covered within the protection scope of the present invention.

Claims

1. A high-temperature resistant acrylic separator adhesive, characterized in that, Comprising: A base film and a high-temperature resistant acrylic slurry coated on both sides of the base film; Among them, the base film is a polyolefin film; the raw materials of the high-temperature resistant acrylic slurry include, by mass: 50 - 100 parts of n-butyl acrylate, 1 - 10 parts of 2-hydroxyethyl acrylate, 50 - 100 parts of nano-ceramic powder, 50 - 80 parts of urea, 5 - 15 parts of graphene oxide, 1 - 4 parts of a first cross-linking agent, 1 - 2 parts of a second cross-linking agent, 0.01 - 0.1 part of an initiator, 5 - 15 parts of polyvinylidene fluoride, 5 - 15 parts of aluminum hydroxide, and 50 - 65 parts of polysiloxane.

2. The high-temperature resistant acrylic diaphragm adhesive according to claim 1, wherein The base film is a polypropylene film, with a thickness of 10 - 20 μm and a porosity of 35 - 45%.

3. The high-temperature resistant acrylic diaphragm adhesive according to claim 1, wherein The first cross-linking agent includes: glutaraldehyde and resorcinol.

4. The high-temperature resistant acrylic diaphragm adhesive according to claim 3, wherein The mass ratio of glutaraldehyde to resorcinol is 4 - 8:2 - 5.

5. The high-temperature resistant acrylic separator adhesive according to claim 1, wherein The second cross-linking agent is benzylidene diisocyanate.

6. The high-temperature resistant acrylic diaphragm adhesive according to claim 1, wherein The initiator is a peroxide initiator.

7. The high-temperature resistant acrylic diaphragm adhesive according to claim 1, wherein The high-temperature resistant acrylic slurry is prepared by the following steps: S1. Add the nano-ceramic powder to an ethanol aqueous solution, ultrasonically treat for 1 - 2 h, add 50 - 80 parts of urea, ball mill for 10 - 20 h, filter, wash, and vacuum dry to obtain amino-functionalized ceramic; S2. Add the amino-functionalized ceramic and graphene oxide to water, stir for 1 - 2 h, add the first cross-linking agent thereto, stir at 60 - 80 °C for 2 - 5 h, directionally freeze for 1 - 3 h, and freeze-dry to obtain a pretreated nano-ceramic powder; S3. Mix n-butyl acrylate, 2-hydroxyethyl acrylate, and the second cross-linking agent, stir at 70 - 90 °C for 1 - 2 h, add the pretreated nano-ceramic powder, initiator, and dimethylacetamide thereto, continue to stir for 1 - 3 h, cool down to 50 - 60 °C, add polyvinylidene fluoride, aluminum hydroxide, and polysiloxane thereto, stir for 10 - 30 min, and cool to room temperature.

8. The high-temperature resistant acrylic diaphragm adhesive according to claim 7, characterized in that, In S2, during the directional freezing process, the cold source is at the bottom, and the freezing temperature is -30 to -50 °C.

9. A method for preparing a high-temperature resistant acrylic diaphragm adhesive according to any one of claims 1-7, characterized in that, Comprising the following steps: Coat the high-temperature resistant acrylic slurry on both sides of the base film, cure at 50 - 80 °C for 5 - 10 min, dry, place in an aqueous solution containing ammonia and vitamin C, perform reduction treatment at 120 - 140 °C for 2 - 4 h, dry, and the obtained coating thickness is 2 - 6 μm.

10. The preparation method of the high-temperature resistant acrylic diaphragm adhesive according to claim 9, wherein, In the aqueous solution containing ammonia and vitamin C, the ammonia concentration is 12 - 18%, and the vitamin C concentration is 0.5 - 1 g / mL.

Images