An antistatic aramid lithium battery separator and its preparation method

Abstract

This invention relates to an antistatic aramid lithium battery separator and its preparation method. The separator comprises an aramid base film, a conductive nano-network layer, and a heat-resistant layer; wherein the conductive nano-network layer has a covalently cross-linked PANI-GO@SiO2 three-dimensional network porous structure. The preparation method of the separator includes the following steps: mixing a conductive particle GO@SiO2 dispersion with one-dimensional PANI, adding a cross-linking agent to construct a covalently cross-linked PANI-GO@SiO2 three-dimensional network structure, and obtaining a conductive slurry; coating the conductive slurry onto the surface of the aramid base film, and then immersing it in a solvent to form a porous structure in the covalently cross-linked PANI-GO@SiO2 three-dimensional network structure; subjecting the immersed aramid base film to hot-press curing treatment to form a conductive nano-network layer; coating a ceramic slurry onto the surface of the conductive nano-network layer to form a heat-resistant layer, thereby obtaining the antistatic aramid lithium battery separator. This invention can solve the problem of static electricity accumulation caused by excessive insulation in traditional aramid separators, while maintaining excellent thermal safety, heat resistance, and cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of lithium metal battery technology, specifically relating to an antistatic aramid lithium battery separator and its preparation method. Background Technology

[0002] With the rapid development of new energy technologies and the booming electric vehicle market, lithium-ion batteries, as a core component of electric vehicles, have become particularly important in terms of safety and performance stability. Among these components, the battery separator, as a crucial element of lithium-ion batteries, determines the battery's interface structure, internal resistance, and other characteristics, directly affecting its capacity, cycle life, and safety performance. To meet the demands for high safety, high-temperature resistant, high-safety separators have become key research areas in lithium-ion batteries.

[0003] Aramid battery separators are playing an increasingly prominent role in the lithium-ion battery field due to their significant advantages in high temperature resistance, electrolyte wettability, mechanical strength, and electrochemical performance, and their market demand will continue to grow. However, due to their high insulation properties, traditional aramid separators are prone to static electricity generation during coating and slitting processes, leading to dust adsorption, discharge risks, and reduced processing efficiency. Furthermore, the accumulation of static electricity can affect the interfacial contact between the separator and the electrolyte, hindering lithium-ion transport and impacting battery rate performance and cycle life. For example, patent CN118970363A discloses a lithium metal battery separator based on aramid nanofibers, its preparation method, and its application. This invention involves deprotonating para-aramid fibers to prepare an aramid nanofiber slurry; preparing a ceramic slurry using solid nano-inorganic ceramic particles and N,N-dimethylacetamide; mixing the aramid nanofiber slurry and the ceramic slurry, adding a pore-forming agent, and then ultrasonically treating to obtain an aramid-ceramic composite slurry; coating the aramid-ceramic composite slurry onto a pre-designed substrate, followed by solvent exchange with deionized water and hot-pressing drying to obtain a lithium metal battery separator based on aramid nanofibers. However, aramid materials are excellent insulators. During high-speed slitting, winding, and battery assembly, the static charge generated by friction cannot be conducted away in time, leading to a static voltage on the separator surface reaching thousands or even tens of thousands of volts. This patent does not consider the high insulation properties of aramid materials and the problem of static electricity generated by friction during coating, slitting, and other processes. Meanwhile, the patent uses para-aramid fiber, which has a larger thermal shrinkage rate at higher temperatures and cannot guarantee thermal stability. The slurry is mixed with solid nano-inorganic ceramic particles, resulting in poor slurry dispersion and difficulty in controlling the coating thickness.

[0004] To address the static electricity problem of aramid materials, patent CN112216928A discloses a modified composite heat-resistant lithium-ion battery separator and its preparation method. This method introduces a polymeric antistatic agent containing hydrophilic and lipophilic groups. The polar segments readily combine with moisture in the air via hydrogen bonds to form conductive channels. The antistatic agent can be distributed in a fine layered or ribbed pattern within the coating. Static electricity within the separator can be transferred to the coating surface via resin, forming a conductive network structure, thus fundamentally solving the static electricity problem. However, the introduction of the polymeric antistatic agent increases the internal resistance of the separator, interfering with lithium-ion transport. Furthermore, the introduction of the conductive network structure cannot guarantee the balance between the ionic conductivity and electronic insulation of the separator, easily leading to direct contact between the positive and negative electrodes and causing a short circuit.

[0005] Therefore, there is an urgent need to research and develop an antistatic aramid lithium battery separator and its preparation method to solve the problem of static electricity accumulation caused by the excessive insulation of traditional aramid separators, while maintaining excellent thermal safety, heat resistance and cycle stability. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an antistatic aramid lithium battery separator and its preparation method, so as to solve the problem of static electricity accumulation caused by the excessive insulation of traditional aramid separators, while maintaining excellent thermal safety, heat resistance and cycle stability.

[0007] To achieve the above objectives, the first aspect of the present invention provides an antistatic aramid lithium battery separator, which includes an aramid base film, a conductive nano-network layer and a heat-resistant layer; wherein the conductive nano-network layer has a covalently cross-linked PANI-GO@SiO2 three-dimensional network porous structure.

[0008] A second aspect of the present invention also provides a method for preparing an antistatic aramid lithium battery separator, the method comprising the following steps:

[0009] Conductive particle GO@SiO2 dispersion was mixed with one-dimensional PANI, a crosslinking agent was added, and the mixture was ultrasonically treated to construct a covalently crosslinked PANI-GO@SiO2 three-dimensional network structure, thus obtaining a conductive slurry.

[0010] The conductive paste is coated onto the surface of the aramid-based film, and the coated aramid-based film is immersed in a solvent to form a porous structure in the covalently cross-linked PANI-GO@SiO2 three-dimensional network structure.

[0011] The aramid-based film after immersion is subjected to hot-press curing treatment to form a conductive nano-network layer on the surface of the aramid-based film.

[0012] A ceramic slurry is coated onto the surface of the conductive nanonetwork layer, and after drying, a heat-resistant layer is formed on the surface of the conductive nanonetwork layer to obtain the antistatic aramid lithium battery separator.

[0013] In some embodiments, the mass ratio of the conductive GO@SiO2 dispersion to the one-dimensional PANI is 1:(1~3); and / or

[0014] The crosslinking agent includes pentylene glycol, and the amount of the crosslinking agent added accounts for 0.1wt% to 0.5wt% of the total mass of the conductive particle GO@SiO2 dispersion and the one-dimensional PANI.

[0015] In some embodiments, the ultrasonic treatment time during the preparation of the conductive paste is 1-2 hours; and / or

[0016] The solid content of the conductive paste is 15wt~25wt%.

[0017] In some embodiments, the coating thickness of the conductive paste is 0.2~1μm; the soaking time is 6~12h.

[0018] In some embodiments, the temperature of the hot-press curing process is 60~80°C and the pressure is 3~5MPa.

[0019] In some embodiments, the method for preparing the conductive particle GO@SiO2 dispersion includes:

[0020] The conductive particles GO@SiO2 were dispersed in an organic solvent and then subjected to ultrasonic and acidification treatment to obtain the GO@SiO2 dispersion.

[0021] In some embodiments, the ultrasonic treatment time is 2-4 hours when preparing the conductive particle GO@SiO2 dispersion; and / or

[0022] The acidification treatment includes acidification with 0.1~0.5 mol / L acid solution at a temperature of 40~60℃ for 6~12 hours.

[0023] In some embodiments, the method for preparing the conductive particles GO@SiO2 includes:

[0024] Conductive nanoparticles (GO) were dispersed in a solvent and subjected to ultrasonic and activation treatment to obtain a conductive nanoparticle (GO) dispersion.

[0025] Tetraethyl orthosilicate, catalyst, dispersant and solvent were added to the conductive nanoparticle GO dispersion. After reaction, conductive particles GO@SiO2 were generated by coating the conductive nanoparticle GO with SiO2.

[0026] The conductive particles GO@SiO2, which are SiO2-coated conductive nanoparticles GO, are prepared by cleaning and drying.

[0027] In some embodiments, the conductive nanoparticles GO are two-dimensional sheet-like GO structures, with a lateral dimension of 0.5~5μm and a thickness of 1~3nm.

[0028] In some embodiments, the ultrasonic treatment time is 30-60 min when preparing the conductive nanoparticle GO dispersion; and / or

[0029] The activation treatment includes adjusting the pH of the system to 3-4 using an acid solution.

[0030] In some embodiments, the mass ratio of the tetraethyl orthosilicate to the GO is 1:(5~10); the mass of the dispersant is 0.1wt%~0.5wt% of the GO mass.

[0031] In some embodiments, the reaction temperature is 40~50°C, the reaction time is 2~6h, and the SiO2 coating thickness is 2~10nm.

[0032] In some embodiments, when preparing conductive particles GO@SiO2, the drying temperature is 60~80°C and the drying time is 12~24h.

[0033] In some embodiments, the aramid-based film is a meta-aramid-based film.

[0034] In some embodiments, the method for preparing the ceramic slurry includes:

[0035] The ceramic slurry is prepared by mixing nano-oxide particles, binder, dispersant and solvent; wherein the content of nano-oxide particles in the ceramic slurry is 30wt%~40wt%; the content of binder is 0.5wt%~5wt%; the content of dispersant is 0.5wt%~1wt%; and the content of solvent is 55wt%~69wt%.

[0036] In some embodiments, the nano-oxide particles include nano-Al2O3 particles and / or nano-SiO2 particles, and the particle size of the nano-oxide particles is 100~300nm.

[0037] In some embodiments, when preparing the heat-resistant layer, the coating thickness of the ceramic slurry is 1~2μm; the drying temperature is 60~80℃, and the drying time is 12~24h.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] The antistatic aramid lithium battery separator provided by this invention comprises an aramid base film, a conductive nano-network layer, and a heat-resistant layer. The conductive nano-network layer has a covalently cross-linked PANI-GO@SiO2 three-dimensional network porous structure, forming a highly efficient electronic conduction path in the plane direction of the separator, and the measured surface resistivity can be reduced to 10. 6 ~10 8 The electrostatic discharge (ESD) is 5-7 orders of magnitude lower than that of pure aramid membranes, eliminating static electricity buildup at its source. Furthermore, the porous structure ensures the discontinuity of the three-dimensional network along the membrane thickness, releasing surface static electricity and effectively preventing internal short circuits. Additionally, the dual heat resistance of the aramid base film and the heat-resistant layer allows the structure to remain intact at high temperatures, significantly improving the battery's thermal safety. Moreover, the strong covalent cross-linked three-dimensional network provides excellent stability, forming a strong bond with the aramid base film, ensuring structural stability in the electrolyte environment and thus enhancing the battery's cycle stability.

[0040] The method for preparing the antistatic aramid lithium battery separator provided by this invention constructs a three-dimensional network with two-dimensional GO@SiO2 as "nodes" and one-dimensional conductive PANI fibers as "connections," forming an efficient electronic conduction path in the plane direction of the separator. The measured surface resistivity can be reduced to 102. 6 ~10 8 The electrostatic discharge (ESD) is reduced by 5-7 orders of magnitude compared to pure aramid membranes, effectively eliminating electrostatic buildup at its source. Furthermore, a porous structure is introduced into the conductive nanonetwork layer via solvent displacement, with its thickness controlled (≤1 μm), ensuring the discontinuity of the three-dimensional network in the membrane thickness direction. This releases surface static electricity and effectively prevents internal short circuits. Additionally, the dual heat resistance of the aramid base film and the heat-resistant layer allows the structure to remain intact at high temperatures, significantly improving the battery's thermal safety. Moreover, this invention utilizes a cross-linking mechanism to form a robust three-dimensional network with covalent bonds, which can be thermo-cured with the aramid base film to form a strong bond, ensuring structural stability of the membrane in the electrolyte environment and thus improving the battery's cycle stability.

[0041] Therefore, the antistatic aramid lithium battery separator and its preparation method provided by the present invention effectively solve the problem of static electricity accumulation caused by excessive insulation of traditional aramid separators, while maintaining excellent thermal safety, heat resistance and cycle stability. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0043] Traditional aramid separators are prone to static electricity buildup due to their excessive insulation properties. This buildup affects the interfacial contact between the separator and the electrolyte, hindering lithium-ion transport and impacting battery rate performance and cycle life. Furthermore, existing methods that address static electricity buildup by adding polymeric antistatic agents to create a conductive network structure increase the separator's internal resistance, interfering with lithium-ion transport. Moreover, the introduction of the conductive network structure cannot guarantee a balance between the separator's ionic conductivity and electronic insulation, easily leading to direct contact between the positive and negative electrodes and causing short circuits.

[0044] Therefore, the present invention provides an antistatic aramid lithium battery separator and a method for preparing the same.

[0045] Without sacrificing the high heat resistance, porous structure, and electrochemical stability of lithium battery separators, a conductive network is formed in the material, and conductive channels are built inside and on the surface of the material to allow static charges to be conducted and released, thereby reducing the surface resistivity and giving it a highly efficient and safe antistatic function. This effectively solves the problem of static electricity accumulation caused by the excessive insulation of traditional aramid separators, while maintaining excellent thermal safety, heat resistance, and cycle stability.

[0046] The meanings of the abbreviations and terms used in this invention are explained as follows:

[0047] GO (Graphene Oxide) refers to graphene oxide.

[0048] PANI (Polyaniline) refers to polyaniline.

[0049] TEOS (Tetraethyl orthosilicate) refers to ethyl orthosilicate.

[0050] CTAB (Cetyltrimethylammonium bromide) refers to hexadecyltrimethylammonium bromide.

[0051] NMP (N-Methyl-2-pyrrolidone) refers to N-methylpyrrolidone.

[0052] PVDF (Polyvinylidene fluoride) refers to polyvinylidene fluoride.

[0053] Z-direction non-continuity guides the formation of non-continuous electron channels in the separator thickness direction of the electro-nano network layer, preventing internal short circuits in the battery.

[0054] GO@SiO2 refers to conductive nanoparticles GO coated with SiO2.

[0055] In a first aspect, embodiments of the present invention provide an antistatic aramid lithium battery separator, which is a composite separator comprising a three-layer structure: an aramid base film, a conductive nano-network layer, and a heat-resistant layer. The conductive nano-network layer has a covalently cross-linked PANI-GO@SiO2 three-dimensional network porous structure.

[0056] The antistatic aramid lithium battery separator provided by this invention features a covalently cross-linked PANI-GO@SiO2 three-dimensional network porous structure in the conductive nano-network layer. This creates a highly efficient electron conduction path in the separator's planar direction, eliminating static electricity buildup at its source. Furthermore, the porous structure ensures the discontinuity of the three-dimensional network in the separator's thickness direction, releasing surface static electricity and effectively preventing internal short circuits. Additionally, the dual heat resistance advantages of the aramid base film and the heat-resistant layer allow the structure to remain intact at high temperatures, significantly improving the battery's thermal safety. Moreover, the strong stability of the covalently cross-linked three-dimensional network allows it to form a strong bond with the aramid base film, ensuring structural stability of the separator in the electrolyte environment and thus improving the battery's cycle stability.

[0057] Secondly, embodiments of the present invention also provide a method for preparing an antistatic aramid lithium battery separator as described in the first aspect of the present invention, comprising the following steps:

[0058] S1, preparing conductive particles GO@SiO2;

[0059] S2, Prepare a GO@SiO2 dispersion of conductive particles;

[0060] S3, the conductive particle GO@SiO2 dispersion was mixed with one-dimensional PANI, a crosslinking agent was added, and the mixture was ultrasonically treated to construct a covalently crosslinked PANI-GO@SiO2 three-dimensional network structure, thus obtaining a conductive slurry;

[0061] S4, the conductive paste is coated onto the surface of the aramid-based film, and the coated aramid-based film is immersed in a solvent to form a porous structure in the covalently cross-linked PANI-GO@SiO2 three-dimensional network structure;

[0062] S5, hot-press curing treatment is performed on the aramid-based film after soaking to form a conductive nano-network layer on the surface of the aramid-based film;

[0063] S6, Preparation of ceramic slurry;

[0064] S7. A ceramic slurry is coated onto the surface of the conductive nano-network layer. After drying, a heat-resistant layer is formed on the surface of the conductive nano-network layer to obtain the antistatic aramid lithium battery separator.

[0065] In step S1, the method for preparing the conductive particles GO@SiO2 includes:

[0066] S11, Disperse conductive nanoparticles GO in a solvent, and then perform ultrasonic and activation treatment to obtain a conductive nanoparticle GO dispersion.

[0067] S12, tetraethyl orthosilicate, catalyst, dispersant and solvent are added to the conductive nanoparticle GO dispersion. After reaction, conductive particles GO@SiO2 are generated by coating the conductive nanoparticle GO with SiO2.

[0068] S13, the conductive particles GO@SiO2 coated with SiO2 are cleaned and dried to obtain the conductive particles GO@SiO2.

[0069] In step S11, the conductive nanoparticles GO used are preferably two-dimensional sheet-like GO with a lateral dimension of 0.5~5μm and a thickness of 1~3nm.

[0070] In step S11, the solvent used to disperse the conductive nanoparticles can be a conventional solvent in the art; exemplarily, deionized water is preferred. The conductive nanoparticles (GO) can be uniformly dispersed in the deionized water by ultrasonic treatment for 30-60 minutes. After ultrasonic treatment, an acid solution is added to the system to adjust the pH to 3-4 for activation treatment to expose surface hydroxyl groups or other active sites. Acids conventional in the art can be used to adjust the pH; exemplarily, hydrochloric acid is preferred.

[0071] In step S12, TEOS is added to the conductive nanoparticle GO dispersion as a SiO2 precursor, with a TEOS-to-GO mass ratio of 1:(5~10). Simultaneously, ammonia water with a concentration of 0.1~0.5 mol / L is slowly injected as a catalyst, and hexadecyltrimethylammonium bromide (CTAB) at 0.1wt%~0.5wt% of the GO mass is used as a dispersant. An ethanol / water mixed solvent (volume ratio 1:2) is used as the reaction medium. The reaction temperature is 40~50℃, allowing the SiO2 precursor TEOS to hydrolyze and uniformly deposit on the surface of the conductive nanoparticle GO. The reaction time is 2~6 h, controlling the SiO2 coating thickness to 2~10 nm. The dispersant hexadecyltrimethylammonium bromide (CTAB) shown here is only an example; other dispersants such as hexadecyltrimethylammonium chloride (CTAC), dodecyltrimethylammonium bromide (DTAB), and octadecyltrimethylammonium chloride (STAC) can also be used.

[0072] In step S13, the conductive particles GO@SiO2 coated with SiO2 are centrifuged and washed to remove unreacted SiO2 precursor TEOS and byproducts, and then vacuum dried at a temperature of 60℃~80℃ for 12~24h to obtain conductive particles GO@SiO2.

[0073] In step S2, the preparation method of the conductive particle GO@SiO2 dispersion includes:

[0074] The conductive particles GO@SiO2 were dispersed in an organic solvent and then subjected to ultrasonic and acidification treatment to obtain the GO@SiO2 dispersion.

[0075] In preparing the above-mentioned conductive particle GO@SiO2 dispersion, conventional organic solvents in the art can be used to disperse the conductive particles GO@SiO2; exemplarily, NMP solvent is preferred. Ultrasonic treatment can be used to uniformly disperse the conductive particles GO@SiO2 in the NMP solvent for 2-4 hours. Subsequently, an acid solution of 0.1-0.5 mol / L is added and acidified at 40-60°C for 6-12 hours. Conventional acids in the art can be used for acidification; exemplarily, nitric acid HNO3 is preferred. Using HNO3 to protonate-dope the subsequently added one-dimensional polyaniline nanofibers PANI greatly improves their conductivity.

[0076] In step S3, the conductive particle GO@SiO2 dispersion is mixed with one-dimensional PANI at a mass ratio of 1:(1~3), and 0.1wt%~0.5wt% of glutaraldehyde (molecular formula OHC(CH2)3CHO) is added as a crosslinking agent. The mixture is ultrasonically treated for 1~2 hours to form a stable conductive slurry. The solid content of the conductive slurry is controlled at 15wt%~25%. The preferred size of the one-dimensional polyaniline nanofiber PANI is 50~100nm in diameter and 1~5μm in length. The aldehyde group (-CHO) of glutaraldehyde (OHC-(CH2)3-CHO) reacts with the amino group (-NH2) on polyaniline (PANI) to form C=N- bonds. At the same time, its aldehyde group can also react with the silanol group (-Si-OH) of the SiO2 shell on the surface of GO@SiO2 particles to form ether bonds (-CO-Si-), thereby constructing a covalently crosslinked PANI-GO@SiO2 three-dimensional network structure.

[0077] In step S4, a conductive paste is coated (by scraping) onto the surface of the aramid-based film. The coating thickness is controlled to be 0.2–1 μm. The aramid-based film is preferably a meta-aramid porous film with a porosity of 40%–60% and a pore size of 0.1–0.3 μm to ensure that the subsequent conductive network can be uniformly dispersed without clogging the pores. The coated aramid-based film is then immersed in a solvent for 6–12 hours, inducing the formation of a porous structure in the covalently cross-linked PANI-GO@SiO2 three-dimensional network structure through solvent displacement. The solvent can be a conventional solvent in the art; deionized water is preferred, for example.

[0078] In step S5, the aramid-based film after soaking is subjected to hot-press curing treatment at a temperature of 60~80℃ and a pressure of 3~5MPa to promote the full cross-linking reaction of glutaraldehyde, enhance the bonding force and mechanical interlock between the conductive layer and the aramid-based film, compact the conductive network, reduce the contact resistance, and maintain the Z-direction discontinuity. Thus, a conductive nano-network layer is formed on the surface of the aramid-based film.

[0079] In step S6, the method for preparing the ceramic slurry includes:

[0080] The ceramic slurry is prepared by mixing nano-oxide particles, binder, dispersant and solvent; wherein the content of nano-oxide particles in the ceramic slurry is 30wt%~40wt%; the content of binder is 0.5wt%~5wt%; the content of dispersant is 0.5wt%~1wt%; and the content of solvent is 55wt%~69wt%.

[0081] In some embodiments, in step S6, the nano-oxide particles include nano-Al2O3 particles and / or nano-SiO2 particles, and the particle size of the nano-oxide particles is 100~300 nm. The solvent can be a conventional organic solvent in the art; exemplarily, NMP is preferred. The binder can be a conventional binder in the art; exemplarily, polyvinylidene fluoride (PVDF) is preferred. The dispersant can be a conventional dispersant in the art, including but not limited to hexadecyltrimethylammonium bromide (CTAB), hexadecyltrimethylammonium chloride (CTAC), dodecyltrimethylammonium bromide (DTAB), octadecyltrimethylammonium chloride (STAC), etc.

[0082] In step S7, a ceramic slurry is coated (by scraping) onto the surface of the conductive nano-network layer with a coating thickness of 1~2μm. After drying at 60~80℃ for 12~24h, a heat-resistant layer is formed on the surface of the conductive nano-network layer, and the antistatic aramid lithium battery separator is finally obtained.

[0083] The method for preparing the antistatic aramid lithium battery separator provided by this invention constructs a three-dimensional network with two-dimensional GO@SiO2 as "nodes" and one-dimensional conductive PANI fibers as "connections," forming an efficient electronic conduction path in the plane direction of the separator. The measured surface resistivity can be reduced to 102. 6 ~10 8 The electrostatic charge (Ω) is reduced by 5-7 orders of magnitude compared to pure aramid membranes, effectively eliminating electrostatic buildup at its source. Furthermore, a porous structure is introduced into the conductive nanonetwork layer via solvent displacement, and its thickness is controlled (≤1 μm), ensuring the discontinuity of the three-dimensional network in the membrane thickness direction. This releases surface static electricity and effectively prevents internal short circuits. Additionally, due to the dual heat resistance advantages of the aramid base film and the heat-resistant layer, the structure remains intact at high temperatures, significantly improving the battery's thermal safety. Moreover, this invention utilizes a cross-linking mechanism to form a robust three-dimensional network with covalent bonds, which can form a strong bond with the aramid base film through hot-pressing curing, ensuring structural stability of the membrane in the electrolyte environment and thus improving the battery's cycle stability.

[0084] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available, all instruments and equipment used are conventional instruments and equipment in the art, and all operating methods used are conventional methods in the art.

[0085] Example

[0086] Example 1

[0087] The antistatic aramid lithium battery separator provided in this embodiment includes a meta-aramid base film, a conductive nano-network layer, and a heat-resistant layer, wherein the conductive nano-network layer has a covalently cross-linked PANI-GO@SiO2 three-dimensional network porous structure.

[0088] The method for preparing the antistatic aramid lithium battery separator provided in this embodiment includes the following steps:

[0089] S1, Preparation of conductive particles GO@SiO2:

[0090] Two-dimensional sheet-like conductive nanoparticles GO (2 μm lateral dimension and 1.5 nm thickness) were dispersed in deionized water, sonicated for 45 min, and activated by adding hydrochloric acid solution to adjust the pH of the system to 3.5, thus obtaining a GO dispersion of conductive nanoparticles.

[0091] TEOS (TEOS to GO mass ratio of 1:8) was added to the conductive nanoparticle GO dispersion as a SiO2 precursor. Simultaneously, 0.3 mol / L ammonia water was slowly injected as a catalyst, 0.3 wt% CTAB was added as a dispersant, and an ethanol / water mixed solvent (volume ratio of 1:2) was added as a reaction medium. The reaction was carried out at 45℃ for 4 h, so that the SiO2 precursor TEOS was hydrolyzed and uniformly deposited on the surface of the conductive nanoparticle GO, generating conductive particles GO@SiO2 coated with SiO2, and the SiO2 coating thickness was 5 nm.

[0092] Conductive particles GO@SiO2, which are SiO2-coated conductive nanoparticles GO, were centrifuged and cleaned, and then dried under vacuum at 70°C for 18 hours to obtain conductive particles GO@SiO2.

[0093] S2, Preparation of conductive particle GO@SiO2 dispersion:

[0094] The conductive particles GO@SiO2 obtained in step S1 were dispersed in NMP solvent and ultrasonically treated for 3 h to form a uniform dispersion. Subsequently, 0.3 mol / L HNO3 solution was added and acidified at 50 °C for 9 h to obtain the conductive particle GO@SiO2 dispersion.

[0095] S3, the conductive particle GO@SiO2 dispersion prepared in step S2 is mixed with one-dimensional PANI (70nm in diameter and 2μm in length) at a mass ratio of 1:2, and glutaraldehyde is added as a crosslinking agent at a mass ratio of 0.3wt% of the total mass of the conductive particle GO@SiO2 dispersion and one-dimensional PANI. The mixture is ultrasonically treated for 1.5h to construct a covalently crosslinked PANI-GO@SiO2 three-dimensional network structure, and a stable conductive slurry is obtained. The solid content of the conductive slurry is 20wt%.

[0096] S4. The conductive paste prepared in step S3 is coated onto the surface of a meta-aramid-based film (thickness 20 μm, porosity 55%, pore size 0.2 μm) with a coating thickness of 0.5 μm. The coated aramid-based film is then immersed in deionized water for 9 h to form a porous structure in the covalently cross-linked PANI-GO@SiO2 three-dimensional network structure.

[0097] S5, the aramid-based film after soaking is subjected to hot pressing curing treatment at a temperature of 70℃ and a pressure of 5MPa to form a conductive nano-network layer on the surface of the aramid-based film.

[0098] S6, Preparation of ceramic slurry:

[0099] A ceramic slurry was prepared by mixing nano-Al2O3 particles (300 nm in diameter), binder PVDF, dispersant CTAB, and NMP solvent. The ceramic slurry contained 35 wt% Al2O3 particles, 2.5 wt% PVDF binder, 0.5 wt% CTAB dispersant, and 62 wt% NMP solvent.

[0100] S7. The ceramic slurry prepared in step S6 is coated onto the surface of the conductive nano-network layer with a coating thickness of 1.5 μm. After drying at 70°C for 12 h, a heat-resistant layer is formed on the surface of the conductive nano-network layer, and finally an antistatic aramid lithium battery separator is obtained.

[0101] Example 2

[0102] The antistatic aramid lithium battery separator provided in this embodiment includes a meta-aramid base film, a conductive nano-network layer, and a heat-resistant layer, wherein the conductive nano-network layer has a covalently cross-linked PANI-GO@SiO2 three-dimensional network porous structure.

[0103] The method for preparing the antistatic aramid lithium battery separator provided in this embodiment includes the following steps:

[0104] S1, Preparation of conductive particles GO@SiO2:

[0105] Two-dimensional sheet-like conductive nanoparticles GO (1 μm in lateral dimension and 2 nm in thickness) were dispersed in deionized water, sonicated for 60 min, and activated by adding hydrochloric acid solution to adjust the pH of the system to 3.0, thus obtaining a GO dispersion of conductive nanoparticles.

[0106] TEOS (TEOS to GO mass ratio of 1:5) was added to the conductive nanoparticle GO dispersion as a SiO2 precursor. At the same time, 0.5 mol / L ammonia water was slowly injected as a catalyst, 0.5 wt% CTAB was added as a dispersant, and an ethanol / water mixed solvent (volume ratio of 1:2) was added as a reaction medium. The reaction was carried out at 50 °C for 2 h, so that the SiO2 precursor TEOS was hydrolyzed and uniformly deposited on the surface of the conductive nanoparticle GO, generating conductive particles GO@SiO2 coated with SiO2, and the SiO2 coating thickness was 8 nm.

[0107] Conductive particles GO@SiO2, which are SiO2-coated conductive nanoparticles GO, were centrifuged and cleaned, and then dried under vacuum at 70°C for 18 hours to obtain conductive particles GO@SiO2.

[0108] S2, Preparation of conductive particle GO@SiO2 dispersion:

[0109] The conductive particles GO@SiO2 obtained in step S1 were dispersed in NMP solvent and ultrasonically treated for 3 h to form a uniform dispersion. Subsequently, 0.5 mol / L HNO3 solution was added and acidified at 60 °C for 6 h to obtain the conductive particle GO@SiO2 dispersion.

[0110] S3, the conductive particle GO@SiO2 dispersion prepared in step S2 is mixed with one-dimensional PANI (70nm in diameter and 2μm in length) at a mass ratio of 1:1, and 0.5wt% of glutaraldehyde as a crosslinking agent is added to the mixture. The mixture is ultrasonically treated for 1 hour to construct a covalently crosslinked PANI-GO@SiO2 three-dimensional network structure, thus obtaining a stable conductive slurry with a solid content of 25wt%.

[0111] S4. The conductive paste prepared in step S3 is coated onto the surface of a meta-aramid-based film (thickness 20 μm, porosity 55%, pore size 0.2 μm) with a coating thickness of 0.8 μm. The coated aramid-based film is then immersed in deionized water for 6 h to form a porous structure in the covalently cross-linked PANI-GO@SiO2 three-dimensional network structure.

[0112] S5, the aramid-based film after soaking is subjected to hot pressing curing treatment at a temperature of 80℃ and a pressure of 5MPa to form a conductive nano-network layer on the surface of the aramid-based film.

[0113] S6, Preparation of ceramic slurry:

[0114] A ceramic slurry was prepared by mixing nano-Al2O3 particles (300 nm in diameter), binder PVDF, dispersant CTAB, and NMP solvent. The ceramic slurry contained 35 wt% Al2O3 particles, 2.5 wt% PVDF binder, 0.5 wt% CTAB dispersant, and 62 wt% NMP solvent.

[0115] S7. The ceramic slurry prepared in step S6 is coated onto the surface of the conductive nano-network layer with a coating thickness of 1.5 μm. After drying at 70°C for 12 h, a heat-resistant layer is formed on the surface of the conductive nano-network layer, and finally an antistatic aramid lithium battery separator is obtained.

[0116] Example 3

[0117] The antistatic aramid lithium battery separator provided in this embodiment includes a meta-aramid base film, a conductive nano-network layer, and a heat-resistant layer, wherein the conductive nano-network layer has a covalently cross-linked PANI-GO@SiO2 three-dimensional network porous structure.

[0118] The method for preparing the antistatic aramid lithium battery separator provided in this embodiment includes the following steps:

[0119] S1, Preparation of conductive particles GO@SiO2:

[0120] Two-dimensional sheet-like conductive nanoparticles GO (4 μm lateral dimension and 1 nm thickness) were dispersed in deionized water, sonicated for 30 min, and activated by adding hydrochloric acid solution to adjust the pH of the system to 4.0, thus obtaining a GO dispersion.

[0121] TEOS (TEOS to GO mass ratio of 1:10) was added to the conductive nanoparticle GO dispersion as a SiO2 precursor. Simultaneously, 0.1 mol / L ammonia water was slowly injected as a catalyst, 0.1 wt% CTAB was added as a dispersant, and an ethanol / water mixed solvent (volume ratio of 1:2) was added as a reaction medium. The reaction was carried out at 40℃ for 6 h, so that the SiO2 precursor TEOS was hydrolyzed and uniformly deposited on the surface of the conductive nanoparticle GO, generating conductive particles GO@SiO2 coated with SiO2, and the SiO2 coating thickness was 2 nm.

[0122] Conductive particles GO@SiO2, which are SiO2-coated conductive nanoparticles GO, were centrifuged and cleaned, and then dried under vacuum at 70°C for 18 hours to obtain conductive particles GO@SiO2.

[0123] S2, Preparation of conductive particle GO@SiO2 dispersion:

[0124] The conductive particles GO@SiO2 obtained in step S1 were dispersed in NMP solvent and ultrasonically treated for 3 h to form a uniform dispersion. Subsequently, 0.1 mol / L HNO3 solution was added and acidified at 40 °C for 12 h to obtain the conductive particle GO@SiO2 dispersion.

[0125] S3, the conductive particle GO@SiO2 dispersion prepared in step S2 is mixed with one-dimensional PANI (70nm in diameter and 2μm in length) at a mass ratio of 1:3, and 0.1wt% of glutaraldehyde as a crosslinking agent is added as the total mass of the conductive particle GO@SiO2 dispersion and one-dimensional PANI. The mixture is ultrasonically treated for 2 hours to construct a covalently crosslinked PANI-GO@SiO2 three-dimensional network structure, and a stable conductive slurry is obtained. The solid content of the conductive slurry is 15wt%.

[0126] S4. The conductive paste prepared in step S3 is coated onto the surface of a meta-aramid-based film (thickness 20 μm, porosity 55%, pore size 0.2 μm) with a coating thickness of 0.3 μm. The coated aramid-based film is then immersed in deionized water for 12 h to form a porous structure in the covalently cross-linked PANI-GO@SiO2 three-dimensional network structure.

[0127] S5, the aramid-based film after soaking is subjected to hot pressing curing treatment at a temperature of 60℃ and a pressure of 5MPa to form a conductive nano-network layer on the surface of the aramid-based film.

[0128] S6, Preparation of ceramic slurry:

[0129] A ceramic slurry was prepared by mixing nano-Al2O3 particles (300 nm in diameter), binder PVDF, dispersant CTAB, and NMP solvent. The ceramic slurry contained 35 wt% Al2O3 particles, 2.5 wt% PVDF binder, 0.5 wt% CTAB dispersant, and 62 wt% NMP solvent.

[0130] S7. The ceramic slurry prepared in step S6 is coated onto the surface of the conductive nano-network layer with a coating thickness of 1.5 μm. After drying at 70°C for 12 h, a heat-resistant layer is formed on the surface of the conductive nano-network layer, and finally an antistatic aramid lithium battery separator is obtained.

[0131] Comparative Example 1 (Pure Aramid Base Film)

[0132] This comparative example directly uses a meta-aramid-based membrane as the lithium battery separator. The parameters of the meta-aramid-based membrane are the same as in Example 1, with a thickness of 20 μm, a porosity of 55%, and a pore size of 0.2 μm.

[0133] Comparative Example 2 (PE base film + heat-resistant layer, no conductive layer)

[0134] The lithium battery separator provided in this comparative example includes a polyethylene (PE) base film (16 μm thick) and a heat-resistant layer.

[0135] The method for preparing the lithium battery separator provided in this comparative example includes the following steps:

[0136] S1, Preparation of ceramic slurry:

[0137] A ceramic slurry was prepared by mixing nano-Al2O3 particles (300 nm in diameter), binder PVDF, dispersant CTAB, and NMP solvent. The ceramic slurry contained 35 wt% Al2O3 particles, 2.5 wt% PVDF binder, 0.5 wt% CTAB dispersant, and 62 wt% NMP solvent.

[0138] S2, the ceramic slurry prepared in step S1 is coated onto the surface of the PE base film with a coating thickness of 3μm. After drying at 70℃ for 12h, a heat-resistant layer is formed on the surface of the PE base film, and finally the lithium battery separator is obtained.

[0139] Comparative Example 3 (No crosslinking agent was used during the preparation of the conductive layer)

[0140] The lithium battery separator provided in this comparative example includes a meta-aramid base film, a conductive nano-network layer, and a heat-resistant layer.

[0141] The method for preparing the lithium battery separator provided in this comparative example includes the following steps:

[0142] S1, Preparation of conductive particles GO@SiO2:

[0143] Two-dimensional sheet-like conductive nanoparticles GO (2 μm lateral dimension and 1.5 nm thickness) were dispersed in deionized water, sonicated for 45 min, and activated by adding hydrochloric acid solution to adjust the pH of the system to 3.5, thus obtaining a GO dispersion of conductive nanoparticles.

[0144] TEOS (TEOS to GO mass ratio of 1:8) was added to the conductive nanoparticle GO dispersion as a SiO2 precursor. Simultaneously, 0.3 mol / L ammonia water was slowly injected as a catalyst, 0.3 wt% CTAB was added as a dispersant, and an ethanol / water mixed solvent (volume ratio of 1:2) was added as a reaction medium. The reaction was carried out at 45℃ for 4 h, so that the SiO2 precursor TEOS was hydrolyzed and uniformly deposited on the surface of the conductive nanoparticle GO, generating conductive particles GO@SiO2 coated with SiO2, and the SiO2 coating thickness was 5 nm.

[0145] Conductive particles GO@SiO2, which are SiO2-coated conductive nanoparticles GO, were centrifuged and cleaned, and then dried under vacuum at 70°C for 18 hours to obtain conductive particles GO@SiO2.

[0146] S2, Preparation of conductive particle GO@SiO2 dispersion:

[0147] The conductive particles GO@SiO2 obtained in step S1 were dispersed in NMP solvent and ultrasonically treated for 3 h to form a uniform dispersion. Subsequently, 0.3 mol / L HNO3 solution was added and acidified at 50 °C for 9 h to obtain the conductive particle GO@SiO2 dispersion.

[0148] S3. The conductive particle GO@SiO2 dispersion obtained in step S2 is mixed with one-dimensional PANI (70nm in diameter and 2μm in length) at a mass ratio of 1:2 and ultrasonically treated for 1.5h to obtain a conductive slurry with a solid content of 20wt%.

[0149] S4. The conductive paste prepared in step S3 is coated onto the surface of a meta-aramid-based film (thickness 20 μm, porosity 55%, pore size 0.2 μm) with a coating thickness of 0.5 μm. The coated aramid-based film is then immersed in deionized water for 9 h to form a porous structure in the covalently cross-linked PANI-GO@SiO2 three-dimensional network structure.

[0150] S5, the aramid-based film after soaking is subjected to hot pressing curing treatment at a temperature of 70℃ and a pressure of 5MPa to form a conductive nano-network layer on the surface of the aramid-based film.

[0151] S6, Preparation of ceramic slurry:

[0152] A ceramic slurry was prepared by mixing nano-Al2O3 particles (300 nm in diameter), binder PVDF, dispersant CTAB, and NMP solvent. The ceramic slurry contained 35 wt% Al2O3 particles, 2.5 wt% PVDF binder, 0.5 wt% CTAB dispersant, and 62 wt% NMP solvent.

[0153] S7. The ceramic slurry prepared in step S6 is coated onto the surface of the conductive nano-network layer with a coating thickness of 1.5 μm. After drying at 70°C for 12 h, a heat-resistant layer is formed on the surface of the conductive nano-network layer, and finally an antistatic aramid lithium battery separator is obtained.

[0154] Comparative Example 4 (aramid-based film + heat-resistant layer, no conductive layer)

[0155] The lithium battery separator provided in this comparative example includes a meta-aramid base film and a heat-resistant layer. The parameters of the meta-aramid base film are the same as those in Example 1, with a thickness of 20 μm, a porosity of 55%, and a pore size of 0.2 μm.

[0156] The method for preparing the lithium battery separator provided in this comparative example includes the following steps:

[0157] S1, Preparation of ceramic slurry:

[0158] A ceramic slurry was prepared by mixing nano-Al2O3 particles (300 nm in diameter), binder PVDF, dispersant CTAB, and NMP solvent. The ceramic slurry contained 35 wt% Al2O3 particles, 2.5 wt% PVDF binder, 0.5 wt% CTAB dispersant, and 62 wt% NMP solvent.

[0159] S2, the ceramic slurry prepared in step S1 is coated onto the surface of the meta-aramid base film with a coating thickness of 1.5 μm. After drying at 70°C for 12 h, a heat-resistant layer is formed on the surface of the meta-aramid base film, and finally the lithium battery separator is obtained.

[0160] Comparative Example 5 (GO was not coated with SiO2 during the preparation of the conductive layer)

[0161] The lithium battery separator provided in this comparative example includes a meta-aramid base film, a conductive nano-network layer, and a heat-resistant layer.

[0162] The method for preparing the lithium battery separator provided in this comparative example includes the following steps:

[0163] S1, Preparation of conductive particle GO dispersion:

[0164] Two-dimensional layered conductive nanoparticles (GO) with a lateral dimension of 2 μm and a thickness of 1.5 nm were dispersed in NMP solvent and sonicated for 3 h to form a uniform dispersion. Subsequently, 0.3 mol / L HNO3 solution was added and acidified at 50 °C for 9 h to obtain the conductive GO dispersion.

[0165] S2, the conductive particle GO dispersion prepared in step S1 is mixed with one-dimensional PANI (70nm in diameter and 2μm in length) at a mass ratio of 1:2, and 0.3wt% of glutaraldehyde as a crosslinking agent is added. The mixture is ultrasonically treated for 1.5h to construct a covalently crosslinked PANI-GO network structure and obtain a conductive slurry with a solid content of 20wt%.

[0166] S3, the conductive paste prepared in step S2 is coated onto the surface of a meta-aramid base film (thickness 20 μm, porosity 55%, pore size 0.2 μm) with a coating thickness of 0.5 μm. The coated aramid base film is then immersed in deionized water for 9 h to form a porous structure in the covalently cross-linked PANI-GO network structure.

[0167] S4, the aramid-based film after soaking is subjected to hot pressing curing treatment at a temperature of 70℃ and a pressure of 5MPa to form a conductive nano-network layer on the surface of the aramid-based film.

[0168] S5, Preparation of ceramic slurry:

[0169] A ceramic slurry was prepared by mixing nano-Al2O3 particles (300 nm in diameter), binder PVDF, dispersant CTAB, and NMP solvent. The ceramic slurry contained 35 wt% Al2O3 particles, 2.5 wt% PVDF binder, 0.5 wt% CTAB dispersant, and 62 wt% NMP solvent.

[0170] S6. The ceramic slurry prepared in step S5 is coated onto the surface of the conductive nano-network layer with a coating thickness of 1.5 μm. After drying at 70°C for 12 h, a heat-resistant layer is formed on the surface of the conductive nano-network layer, and finally an antistatic aramid lithium battery separator is obtained.

[0171] Comparative Example 6 (no solvent replacement was performed during the preparation of the conductive layer)

[0172] The lithium battery separator provided in this comparative example includes a meta-aramid base film, a conductive nano-network layer, and a heat-resistant layer.

[0173] The method for preparing the lithium battery separator provided in this comparative example includes the following steps:

[0174] S1, Preparation of conductive particles GO@SiO2:

[0175] Two-dimensional sheet-like conductive nanoparticles GO (2 μm lateral dimension and 1.5 nm thickness) were dispersed in deionized water, sonicated for 45 min, and activated by adding hydrochloric acid solution to adjust the pH of the system to 3.5, thus obtaining a GO dispersion of conductive nanoparticles.

[0176] TEOS (TEOS to GO mass ratio of 1:8) was added to the conductive nanoparticle GO dispersion as a SiO2 precursor. Simultaneously, 0.3 mol / L ammonia water was slowly injected as a catalyst, 0.3 wt% CTAB was added as a dispersant, and an ethanol / water mixed solvent (volume ratio of 1:2) was added as a reaction medium. The reaction was carried out at 45℃ for 4 h, so that the SiO2 precursor TEOS was hydrolyzed and uniformly deposited on the surface of the conductive nanoparticle GO, generating conductive particles GO@SiO2 coated with SiO2, and the SiO2 coating thickness was 5 nm.

[0177] Conductive particles GO@SiO2, which are SiO2-coated conductive nanoparticles GO, were centrifuged and cleaned, and then dried under vacuum at 70°C for 18 hours to obtain conductive particles GO@SiO2.

[0178] S2, Preparation of conductive particle GO@SiO2 dispersion:

[0179] The conductive particles GO@SiO2 obtained in step S1 were dispersed in NMP solvent and ultrasonically treated for 3 h to form a uniform dispersion. Subsequently, 0.3 mol / L HNO3 solution was added and acidified at 50 °C for 9 h to obtain the conductive particle GO@SiO2 dispersion.

[0180] S3, the conductive particle GO@SiO2 dispersion prepared in step S2 is mixed with one-dimensional PANI (70nm in diameter and 2μm in length) at a mass ratio of 1:2, and glutaraldehyde is added as a crosslinking agent at a mass ratio of 0.3wt% of the total mass of the conductive particle GO@SiO2 dispersion and one-dimensional PANI. The mixture is ultrasonically treated for 1.5h to construct a covalently crosslinked PANI-GO@SiO2 three-dimensional network structure, and a stable conductive slurry is obtained. The solid content of the conductive slurry is 20wt%.

[0181] S4. The conductive paste prepared in step S3 is coated onto the surface of a meta-aramid base film (thickness 20 μm, porosity 55%, pore size 0.2 μm) with a coating thickness of 0.5 μm.

[0182] S5, the coated aramid-based film is hot-pressed and cured at a temperature of 70℃ and a pressure of 5MPa to form a conductive nano-network layer on the surface of the aramid-based film.

[0183] S6, Preparation of ceramic slurry:

[0184] A ceramic slurry was prepared by mixing nano-Al2O3 particles (300 nm in diameter), binder PVDF, dispersant CTAB, and NMP solvent. The ceramic slurry contained 35 wt% Al2O3 particles, 2.5 wt% PVDF binder, 0.5 wt% CTAB dispersant, and 62 wt% NMP solvent.

[0185] S7. The ceramic slurry prepared in step S6 is coated onto the surface of the conductive nano-network layer with a coating thickness of 1.5 μm. After drying at 70°C for 12 h, a heat-resistant layer is formed on the surface of the conductive nano-network layer, and finally an antistatic aramid lithium battery separator is obtained.

[0186] The performance of the lithium battery separators prepared in Examples 1-3 and Comparative Examples 1-6 was tested, and the specific test methods are as follows:

[0187] (1) Surface resistivity (Ω): Measured using a surface resistivity tester in a dry environment at room temperature according to ASTM D257 standard.

[0188] (2) Static voltage (kV): A static voltage meter (or Faraday cylinder method) is used. After rubbing a diaphragm sample with an area of ​​10cm×10cm with a standard nylon cloth (friction material) at a speed of 1m / s and a pressure of 500Pa 10 times, the surface static voltage value is quickly measured.

[0189] (3) Heat shrinkage rate (%): The diaphragm was cut into a certain size (100mm×100mm), placed in a forced-air drying oven, and kept at 150℃ for 1 hour. The diameter change before and after heating was measured, and the area shrinkage rate was calculated. The calculation formula is shown in Formula I:

[0190] Heat shrinkage rate (%) = [(initial area - area after heating) / initial area] × 100% (Equation I)

[0191] (4) Ionic conductivity (S / cm): Assembled stainless steel (SS) symmetrical cells (SS|separator|SS) were tested by electrochemical impedance spectroscopy (EIS) in the frequency range of 0.1 Hz to 100 kHz with an amplitude of 10 mV. The formula for calculating ionic conductivity (σ) is shown in Equation II:

[0192] σ=d / (Rb×A) (Equation II)

[0193] In Equation II, d is the diaphragm thickness (cm), Rb is the resistance (Ω, obtained by the intercept of the high-frequency region of the EIS spectrum with the real axis), and A is the area of ​​the stainless steel electrode (cm²). 2 ).

[0194] (5) Electrochemical stability window (V): The lithium metal battery (Li|separator|SS) was assembled and linear sweep voltammetry (LSV) was used at a scan rate of 1 mV / s, scanning from the open circuit potential to 6 V (relative to the lithium ion / lithium metal electrode).

[0195] (6) Battery cycle performance: A 2032 coin cell was assembled using NCM811 as the positive electrode and graphite as the negative electrode. Constant current charge-discharge cycle test was performed at 1C rate, and the capacity retention rate (%) after 500 cycles was recorded.

[0196] See Table 1 for specific performance test results.

[0197] Table 1

[0198]

[0199] As can be seen from Table 1:

[0200] Regarding antistatic properties, all embodiments achieved excellent antistatic performance (surface resistivity of 10). 6 ~10 8 Ω, electrostatic voltage <0.6kV). Compared with the examples: Comparative Example 1 (containing only the aramid-based film layer) has serious electrostatic problems and cannot be practically applied. Comparative Example 4 (containing only the aramid-based film layer and the heat-resistant ceramic layer, without the conductive layer) also has serious electrostatic problems and cannot be practically applied, which shows that the heat-resistant ceramic layer alone cannot solve the electrostatic problem.

[0201] In terms of thermal stability, all aramid-based samples performed excellently, far surpassing Comparative Example 2 (based on PE film).

[0202] In terms of electrochemical performance, the ionic conductivity of Comparative Example 6 (without solvent replacement) decreased sharply (3.5 × 10⁻⁶). -4 The lowest ionic conductivity (S / cm) and the worst cycling performance indicate that the "solvent displacement" step is beneficial for forming a Z-axis discontinuous, ion-permeable porous structure. Comparative Example 5 (without SiO2 coating) also has a low ionic conductivity, which is because the aggregated GO partially blocks the pores.

[0203] In terms of cycling performance and structural stability, both Comparative Example 3 (without crosslinking agent) and Comparative Example 5 (without SiO2 coating) showed a significant decrease in cycling performance, poor coating adhesion, and unsustainable performance. This indicates that both SiO2 coating and the use of glutaraldehyde crosslinking agent are beneficial for building a stable interface and long-term durability.

[0204] In summary, the antistatic aramid lithium battery separator and its preparation method provided by this invention can effectively solve the problem of static electricity accumulation caused by excessive insulation of traditional aramid separators, while maintaining excellent thermal safety, heat resistance and cycle stability.

[0205] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0206] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified.

[0207] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing an antistatic aramid lithium battery separator, characterized in that, The preparation method includes the following steps: Conductive particle GO@SiO2 dispersion was mixed with one-dimensional PANI, a crosslinking agent was added, and the mixture was ultrasonically treated to construct a covalently crosslinked PANI-GO@SiO2 three-dimensional network structure, thus obtaining a conductive slurry; the crosslinking agent included glutaraldehyde. The conductive paste is coated onto the surface of the aramid-based film, and the coated aramid-based film is immersed in a solvent to form a porous structure in the covalently cross-linked PANI-GO@SiO2 three-dimensional network structure. The aramid-based film after immersion is subjected to hot-press curing treatment to form a conductive nano-network layer on the surface of the aramid-based film. A ceramic slurry is coated onto the surface of the conductive nano-network layer, and after drying, a heat-resistant layer is formed on the surface of the conductive nano-network layer to obtain the antistatic aramid lithium battery separator. The preparation method of the conductive particle GO@SiO2 dispersion includes: The conductive particles GO@SiO2 were dispersed in an organic solvent and then subjected to ultrasonic and acidification treatment to obtain the GO@SiO2 dispersion. The method for preparing the conductive particles GO@SiO2 includes: Conductive nanoparticles (GO) were dispersed in a solvent and subjected to ultrasonic and activation treatment to obtain a conductive nanoparticle (GO) dispersion. Tetraethyl orthosilicate, catalyst, dispersant and solvent were added to the conductive nanoparticle GO dispersion. After reaction, conductive particles GO@SiO2 were generated by coating the conductive nanoparticle GO with SiO2. The conductive particles GO@SiO2, which are SiO2-coated conductive nanoparticles GO, are prepared by cleaning and drying.

2. The method for preparing the antistatic aramid lithium battery separator according to claim 1, characterized in that, The mass ratio of the conductive particles GO@SiO2 dispersion to the one-dimensional PANI is 1:(1~3); and / or The amount of the crosslinking agent added is 0.1wt% to 0.5wt% of the total mass of the conductive particles GO@SiO2 dispersion and the one-dimensional PANI.

3. The method for preparing the antistatic aramid lithium battery separator according to claim 1, characterized in that, The ultrasonic treatment time is 1-2 hours; and / or The solid content of the conductive paste is 15wt~25wt%.

4. The method for preparing the antistatic aramid lithium battery separator according to claim 1, characterized in that, The coating thickness of the conductive paste is 0.2~1μm; the soaking time is 6~12h.

5. The method for preparing the antistatic aramid lithium battery separator according to claim 1, characterized in that, The temperature of the hot-press curing process is 60~80℃, and the pressure is 3~5MPa.

6. The method for preparing the antistatic aramid lithium battery separator according to claim 1, characterized in that, The ultrasonic treatment time is 2-4 hours; and / or The acidification treatment includes acidification with 0.1~0.5 mol / L acid solution at a temperature of 40~60℃ for 6~12 hours.

7. The method for preparing the antistatic aramid lithium battery separator according to claim 1, characterized in that, The conductive nanoparticles GO are two-dimensional sheet structures with a lateral dimension of 0.5~5μm and a thickness of 1~3nm.

8. The method for preparing the antistatic aramid lithium battery separator according to claim 1, characterized in that, The ultrasonic treatment time is 30-60 minutes; and / or The activation treatment includes adjusting the pH of the system to 3-4 using an acid solution.

9. The method for preparing the antistatic aramid lithium battery separator according to claim 1, characterized in that, The mass ratio of the tetraethyl orthosilicate to the GO is 1:(5~10). The mass of the dispersant is 0.1wt% to 0.5wt% of the mass of GO.

10. The method for preparing the antistatic aramid lithium battery separator according to claim 1, characterized in that, The reaction temperature is 40~50℃, the reaction time is 2~6h, and the SiO2 coating thickness is 2~10nm.

11. The method for preparing the antistatic aramid lithium battery separator according to claim 1, characterized in that, The drying process is carried out at a temperature of 60-80°C for 12-24 hours.

12. The method for preparing the antistatic aramid lithium battery separator according to claim 1, characterized in that, The aramid-based film is a meta-aramid-based film.

13. The method for preparing the antistatic aramid lithium battery separator according to claim 1, characterized in that, The method for preparing the ceramic slurry includes: The ceramic slurry is prepared by mixing nano-oxide particles, binder, dispersant and solvent. The ceramic slurry contains 30wt% to 40wt% nano-oxide particles; the binder contains 0.5wt% to 5wt%; the dispersant contains 0.5wt% to 1wt%; and the solvent contains 55wt% to 69wt%.

14. The method for preparing the antistatic aramid lithium battery separator according to claim 13, characterized in that, The nano-oxide particles include nano-Al2O3 particles and / or nano-SiO2 particles, and the particle size of the nano-oxide particles is 100~300nm.

15. The method for preparing the antistatic aramid lithium battery separator according to claim 1, characterized in that, The coating thickness of the ceramic slurry is 1~2μm; the drying temperature is 60~80℃, and the drying time is 12~24h.

16. An antistatic aramid lithium battery separator, characterized in that, It is prepared by any one of the preparation methods described in claims 1-15; the antistatic aramid lithium battery separator includes an aramid base film, a conductive nano-network layer and a heat-resistant layer; wherein, the conductive nano-network layer has a covalently cross-linked PANI-GO@SiO2 three-dimensional network porous structure.

Images