Lithium-ion batteries, battery separators and their preparation methods

Abstract

This invention discloses a lithium-ion battery, a battery separator, and a method for preparing the same. The separator includes a base film and a coating layer; the coating layer includes a PAN@C@LATP composite material. This technical solution prepares a titanium aluminum phosphate composite material coated with PAN and carbon materials. The carbon material provides a good conductive network, which is beneficial for lithium-ion transport and meets the ion conduction requirements of the battery during normal operation, ensuring good charge and discharge performance. PAN itself has a certain degree of viscosity; when combined with carbon materials, the carbon materials enhance the overall structure and mechanical properties of the composite material, helping to improve adhesion. Simultaneously, PAN and carbon materials have good thermal stability, which can withstand the heat generated during battery operation to a certain extent, reducing problems such as separator deformation and damage caused by temperature increases, thus improving battery safety.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a lithium-ion battery, a battery separator, and a method for preparing the same. Background Technology

[0002] The separator is an important component of a single cell battery, and its main function is to separate the positive electrode material from the negative electrode material.

[0003] In the prior art, the diaphragm is usually a polymer diaphragm, such as a polyethylene or polypropylene polyolefin porous membrane. The polymer material has a low melting point. When the temperature is increased, the polymer diaphragm will shrink and melt, which can cause the electrode to short circuit under conditions such as overcharging, and thus lead to thermal runaway.

[0004] To address this, Chinese invention patent application CN116826313A discloses a flame-retardant separator for lithium-ion batteries and its preparation method. The flame-retardant separator includes a base film and a coating layer. The coating layer includes a Mg(OH)2@LATP composite material, which contains LATP, exhibiting good low flammability and high-temperature resistance. The Mg(OH)2 component also possesses excellent flame retardancy. However, Mg(OH)2 itself has relatively low ionic conductivity, which to some extent affects the ion transport efficiency of the entire composite material, especially in high-power applications, failing to meet the requirements of rapid charging and discharging. Furthermore, Mg(OH)2 is a plate-like crystal or powder with weak adhesion, easily peeling off from the electrode. Simultaneously, under high-temperature conditions, Mg(OH)2 is prone to decomposition, affecting separator performance and battery safety.

[0005] Therefore, there is an urgent need to research a battery separator that can maintain good lithium-ion conductivity and high adhesion, improve the thermal stability of the separator, and ensure high safety, thereby overcoming the shortcomings of the existing composite materials and improving the safety of lithium-ion batteries. Summary of the Invention

[0006] The main objective of this invention is to provide a lithium-ion battery, a battery separator, and a method for preparing the same, aiming to solve the technical problem that existing composite materials used for separators cannot simultaneously maintain good lithium-ion conductivity and adhesion while further improving the thermal stability of the separator.

[0007] To achieve the above objectives, the first aspect of the present invention provides a battery separator, comprising a base film and a coating layer; the coating layer comprises a PAN@C@LATP composite material.

[0008] Furthermore, the coating layer also includes a dispersant, a thickener, a binder, and a wetting agent.

[0009] Furthermore, the dispersant is any one of hydrolyzed polymaleic anhydride, lauramide, polyethylene wax, and ethyl acetate; the thickener is any one of sodium hydroxymethyl cellulose, hydroxyethyl cellulose, and methyl cellulose; and the binder is any one of polyacrylic acid, polyacrylamide, and polyvinyl alcohol.

[0010] Furthermore, the wetting agent is a silanol nonionic surfactant.

[0011] Furthermore, the base film is a porous thin film.

[0012] Furthermore, the carbon group in the PAN@C@LATP composite material is polymer-derived porous carbon.

[0013] A second aspect of this invention provides a method for preparing a battery separator, comprising the following steps:

[0014] The PAN@C@LATP composite material and dispersant were added to the first solvent and mixed thoroughly.

[0015] Thickener, binder, and wetting agent are added and mixed evenly to obtain the coating slurry of PAN@C@LATP composite material;

[0016] The coating slurry is uniformly coated onto the base film, and after drying, the battery separator is obtained.

[0017] Furthermore, the components of the coating slurry, by weight fraction, are: PAN@C@LATP composite material 18%–38%, thickener 0.2%–1.0%, binder 0.3%–1.7%, wetting agent 0.05%–0.55%, dispersant 0.1%–1.0%, and the remainder is the first solvent.

[0018] Furthermore, prior to the step of adding the PAN@C@LATP composite material and dispersant to the solvent and mixing them thoroughly, the following steps are also included:

[0019] An organic base and an acidic solution are added to a second solvent and allowed to react fully to obtain a buffer solution.

[0020] LATP powder and a carbon source were added to the buffer solution and allowed to react fully to obtain a polymer-modified LATP material.

[0021] The polymer-modified LATP material was carbonized to obtain a C@LATP composite material.

[0022] Furthermore, after the step of carbonizing the polymer-modified LATP material to obtain the C@LATP composite material, the method further includes the following steps:

[0023] The C@LATP composite material was placed in a mixed gas of argon and oxygen for heating treatment.

[0024] Furthermore, after the step of placing the C@LATP composite material in a mixed gas of argon and oxygen for heat treatment, the method further includes the following steps:

[0025] The C@LATP composite material was dispersed in a third solvent to obtain a dispersion of the C@LATP composite material.

[0026] PAN powder is dissolved in a fourth solvent under a sealed environment to obtain a PAN solution;

[0027] The PAN solution was added to the dispersion and mixed thoroughly to obtain the PAN@C@LATP composite material.

[0028] A third aspect of the present invention provides a lithium-ion battery, comprising a separator as described in any of the preceding claims.

[0029] Beneficial effects:

[0030] This invention discloses a battery separator, comprising a base film and a coating layer; the coating layer comprises a PAN@C@LATP composite material. This technical solution prepares a titanium aluminum phosphate composite material coated with PAN and carbon materials. The carbon material provides a good conductive network, which is beneficial for lithium-ion transport and meets the ion conduction requirements of the battery during normal operation, ensuring good charge and discharge performance. PAN itself has a certain degree of viscosity; when combined with carbon materials, the carbon materials enhance the overall structure and mechanical properties of the composite material, helping to improve adhesion. Simultaneously, PAN and carbon materials have good thermal stability, capable of withstanding the heat generated during battery operation to a certain extent, reducing separator deformation and damage caused by temperature increases, and improving battery safety.

[0031] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments. Detailed Implementation

[0032] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0033] In this application, some industry terms are explained as follows:

[0034] PAN: Polyacrylonitrile; LATP: Lithium Aluminum Titanium Phosphate; Thermal shrinkage rate: The degree of dimensional shrinkage of a material after heating, evaluated as the ratio of the change in size to the original size, where MD% (Machine Direction) represents the longitudinal shrinkage rate, and TD% (Transverse Direction) represents the transverse shrinkage rate; Air permeability: The time required for a certain volume of air to pass through a certain area of ​​material under a specific pressure, measured in seconds per 100 milliliters (s / 10 mls), reflecting the pore structure and pore size distribution of the membrane; Coating areal density: The ratio of the mass of the coating material applied to the surface of a specific material to the area covered by the coating, measured in grams per square meter (g / m²). 2 The unit is ); Anode-thermal stripping: Under specific temperature conditions, the battery separator that is attached to the electrode is heated and then peeled off from the electrode.

[0035] One embodiment of the present invention provides a battery separator, comprising a base film and a coating layer; the coating layer comprises a PAN@C@LATP composite material.

[0036] In the above embodiments, carbon materials can provide a good conductive network, which is beneficial to the transport of lithium ions and can meet the ion conduction requirements of the battery during normal operation, ensuring that the battery has good charge and discharge performance. PAN itself has a certain degree of viscosity. When it is combined with carbon materials, the carbon materials enhance the overall structure and mechanical properties of the composite material, which helps to improve the bonding performance. At the same time, PAN and carbon materials have good thermal stability and can withstand the heat generated during battery operation to a certain extent. This can reduce problems such as separator deformation and damage caused by temperature rise, which is beneficial to improving battery safety.

[0037] In one embodiment, the dispersant is any one of hydrolyzed polymaleic anhydride, lauramide, polyethylene wax, and ethyl acetate; the thickener is any one of sodium hydroxymethyl cellulose, hydroxyethyl cellulose, and methyl cellulose; and the binder is any one of polyacrylic acid, polyvinylidene fluoride, styrene-butadiene rubber, epoxy resin, and phenolic resin.

[0038] In this embodiment, the dispersant is a substance that promotes the uniform dispersion of solid particles in a liquid. Any one of hydrolyzed polymaleic anhydride, lauramide, polyethylene wax, ethyl acetate, or sodium polyacrylate can be used as a dispersant to ensure the uniform dispersion of the PAN@C@LATP composite material in the solvent, preventing agglomeration. This helps ensure a uniform distribution of the coating layer's components, thereby guaranteeing the consistency of the overall membrane performance. When the composite material is uniformly dispersed, the carbon material can better construct a conductive network, improving lithium-ion transport efficiency. The thickener is a substance that increases the viscosity of a liquid. Sodium hydroxymethyl cellulose, hydroxyethyl cellulose, and methyl cellulose can increase the viscosity of the coating slurry. Appropriate viscosity allows the coating slurry to adhere better to the base membrane, preventing problems such as sagging and dripping during preparation, and ensuring the uniformity of the coating layer thickness. Furthermore, the thickened slurry is easier to control during coating, helping to improve production efficiency and product quality. In addition, the thickener can also enhance the mechanical strength of the coating layer to a certain extent, improving the membrane's durability. The binder is a substance with adhesive properties that can bond different materials together. The binder is selected from any one of polyacrylic acid, polyvinylidene fluoride, styrene-butadiene rubber, epoxy resin, and phenolic resin. Its main function is to enhance the adhesion between the coating layer and the base film. Good adhesion ensures that the coating layer is firmly attached to the base film and will not fall off during battery use due to volume changes, mechanical stress, or other factors during charging and discharging. This is crucial for maintaining the structural integrity and stability of the separator, ensuring long-term stable battery operation, and also contributing to improved battery safety. A wetting agent is a substance that reduces the surface tension of a liquid and improves the wettability of the liquid on a solid surface. Silicon alcohol nonionic surfactants, as wetting agents, can improve the wettability of the coating slurry to the base film. Good wettability allows the coating slurry to more fully wet the base film surface, reducing the generation of pores and defects, and making the coating more uniform. A uniform coating layer provides more stable ion transport channels and better thermal stability, reducing battery performance degradation and safety risks caused by local performance differences. At the same time, the wetting agent can also improve the flowability of the coating slurry, making it easier to spread on the base film, further improving the convenience of the production process and product quality.

[0039] In the above embodiments, the dry molecular structure of hydrolyzed polymaleic acid contains a large number of carboxyl groups, which can prevent particle agglomeration through electrostatic repulsion or steric hindrance, so that the particles are uniformly dispersed in the solution. Its polyelectrolyte properties are stable, and its chemical structure is not easily destroyed under harsh conditions such as high temperature and high pH, ​​thus maintaining good performance. The amide group in laurylamide has a certain polar and non-polar structure, which allows it to interact with the particle surface and be well compatible with the solvent, thereby playing a dispersing role. Its long-chain alkyl part (non-polar part) can interact with organic solvents, while the amide group (polar part) can be adsorbed on the surface of PAN@C@LATP composite material particles, preventing particle agglomeration through steric hindrance. However, compared with hydrolyzed polymaleic anhydride, its electrostatic repulsion is weaker, and the dispersion effect is relatively limited. Polyethylene wax can form a waxy film on the surface of PAN@C@LATP composite material particles. When preparing battery separator coating slurry, it can reduce the friction between particles and make the particles uniformly dispersed. However, in strongly polar solvents or high-temperature oxygen environments, oxidation and decomposition may occur, thus affecting its dispersion effect. Ethyl acetate has ester bonds, which can have a good adsorption effect on PAN@C@LATP composite particles. In addition, the alkyl groups in its molecular structure can interact with organic solvents to improve the dispersibility of particles in solvents. However, compared with hydrolyzed polymaleic anhydride, ester dispersants are more prone to hydrolysis in acidic or alkaline environments. Therefore, in this embodiment, hydrolyzed polymaleic anhydride is preferred as the dispersant.

[0040] Thickeners such as hydroxyethyl cellulose, carboxymethyl cellulose, and sodium hydroxymethyl cellulose can all increase the viscosity of a solution through interaction with the solvent. Sodium hydroxymethyl cellulose, whose main raw material is natural cellulose, is widely available and relatively inexpensive; therefore, it is preferred as the thickener in this embodiment. Binders such as polyacrylic acid, polyacrylamide, and polyvinyl alcohol are polymers with similar carboxyl functional groups, capable of forming chemical bonds or hydrogen bonds with components in the base film and coating layer, thus acting as binders. Due to its excellent water solubility, polyacrylic acid can be easily mixed with other water-soluble substances to form a uniform slurry during electrode material preparation, which is beneficial for the uniform dispersion of active materials, conductive agents, etc., thereby improving the electrochemical performance of the electrode. Therefore, polyacrylic acid is preferred as the binder in this embodiment. Silicon alcohol nonionic surfactants, as wetting agents, are nonionic surfactants that reduce surface tension and improve the wettability of liquids to solids. Examples include polyoxyethylene ethers and polyol esters, which can improve wetting performance by altering the interfacial properties of the liquid and solid surfaces.

[0041] In one embodiment, the base film is a porous thin film.

[0042] In this embodiment, the porous thin film serves as the base film, providing fundamental physical support for the entire battery separator. It possesses sufficient strength and toughness to withstand various mechanical stresses within the battery, such as the expansion and contraction of electrode materials and pressure during assembly. This physical support ensures the stability and reliability of the separator during battery use, preventing separator rupture or damage, thereby guaranteeing normal battery operation. Furthermore, it prevents direct contact between the positive and negative electrodes, preventing short circuits. Simultaneously, its porosity allows lithium ions to freely move between the positive and negative electrodes, facilitating the battery's charging and discharging processes.

[0043] Specifically, the porous membrane is a polyolefin separator. In the battery's operating environment, the polyolefin separator remains stable and does not readily react chemically with the electrolyte, electrode materials, etc., ensuring stable battery performance. The polyolefin separator possesses high tensile strength, puncture resistance, and other mechanical properties, enabling it to withstand various mechanical stresses during battery assembly and use. For example, during battery production and assembly, the separator undergoes winding and encapsulation processes; the high strength of the polyolefin separator ensures it will not easily break or be damaged during these processes. During battery use, the expansion and contraction of the electrode materials also exert mechanical pressure on the separator; the polyolefin separator can withstand this pressure, maintaining the integrity of the battery structure.

[0044] In one embodiment, the carbon group in the PAN@C@LATP composite material is polymer-derived porous carbon.

[0045] In this embodiment, polymer-derived porous carbon is a carbon material with a porous structure obtained by carbonizing a polymer. As a carbon-based material, polymer-derived porous carbon possesses abundant pore structure and a high specific surface area. These characteristics enable it to provide a good conductive network for lithium-ion transport. Lithium ions can move rapidly within the pores of porous carbon, thereby improving the charge-discharge performance of the battery. Compared with traditional carbon materials, the pore structure of polymer-derived porous carbon is more uniform and controllable, better adapting to the lithium-ion transport requirements. The high specific surface area and pore structure of porous carbon allow it to fully contact and bond with materials such as PAN and LATP. This bonding enhances the overall structural stability of the composite material and improves its mechanical properties. During battery use, the composite material needs to withstand various stresses such as the expansion and contraction of electrode materials and the erosion of electrolytes. The presence of polymer-derived porous carbon can effectively disperse these stresses, preventing the composite material from cracking and being damaged. The performance of polymer-derived porous carbon can be controlled by adjusting its preparation process and parameters. For example, the pore structure, specific surface area, and electrical conductivity of porous carbon can be controlled by adjusting parameters such as the type of polymer, carbonization temperature, and time. This tunability allows us to design and prepare PAN@C@LATP composite materials with specific properties to meet different battery application requirements, thereby improving battery performance and adaptability.

[0046] Specifically, the polymer-derived porous carbon of this application includes polydopamine-derived porous carbon, phenolic resin-derived porous carbon, polypyrrole-derived porous carbon, and polyaniline-derived porous carbon. Among these, dopamine contains abundant active groups and can undergo polymerization under certain conditions to form polydopamine. Polydopamine exhibits strong adhesion and modifiability, and can form uniform coatings on various material surfaces. High-temperature carbonization of polydopamine yields polydopamine-derived porous carbon materials. By controlling the carbonization conditions of polydopamine, pore structures with different pore sizes and distributions can be formed, including micropores, mesopores, and macropores. This abundant pore structure provides numerous channels and active sites for ion transport, gas adsorption, and storage.

[0047] Another embodiment of the present invention provides a method for preparing a battery separator, which includes the following steps:

[0048] Add the PAN@C@LATP composite material and dispersant to the first solvent and mix thoroughly.

[0049] Thickener, binder, and wetting agent are added in sequence and mixed evenly to obtain the coating slurry of PAN@C@LATP composite material;

[0050] The coating slurry is uniformly coated onto the base film, and after drying, the battery separator is obtained.

[0051] In this embodiment, the dispersant is hydrolyzed polymaleic anhydride. The first solvent can be ultrapure water, or an organic solvent such as ethanol or acetone, to ensure that the dispersant is uniformly dispersed in the system, so as to better exert its function in dispersing the PAN@C@LATP composite material; at the same time, it provides a uniform mixing environment for the PAN@C@LATP composite material and the subsequently added thickeners, binders, wetting agents, etc., promoting the interaction and uniform dispersion of the components.

[0052] In one embodiment, the components of the coating slurry, by weight fraction, are: PAN@C@LATP composite material 18%–38%, thickener 0.2%–1.0%, binder 0.3%–1.7%, wetting agent 0.05%–0.55%, dispersant 0.1%–1.0%, and the remainder is the first solvent.

[0053] In this embodiment, the proportion of PAN@C@LATP composite material is within the range of 18% to 38% to ensure good ion conductivity, thermal stability, and mechanical properties. The proportion cannot be too low, otherwise it will not be able to fully exert its role in enhancing battery performance, such as providing a conductive network, improving adhesion, and thermal stability. If the proportion is too high, the coating slurry will be too thick, making it difficult to coat evenly on the base film, and performance will be reduced. The proportion of thickener is 0.2% to 1.0% to ensure better adhesion to the base film. If the proportion is too low, the required viscosity cannot be achieved, and the coating layer will have problems such as sagging and uneven thickness; if the proportion is too high, the slurry will be too viscous, difficult to handle, and will affect the dispersibility of other components and ion transport performance. The proportion of binder is 0.3% to 1.7% to ensure that the coating layer will not fall off during battery use. If the proportion is too low, the adhesion will be insufficient, easily leading to separation of the coating layer from the base film; if the proportion is too high, it may affect the flowability of the coating slurry. The wetting agent ratio is 0.05%–0.55%, which allows the slurry to spread better on the base film surface, reducing the formation of pores and defects. If the ratio is too low, the wetting effect is not obvious, leading to uneven coating; if the ratio is too high, it increases costs. The dispersant ratio is 0.1%–1.0%. If the ratio is too low, the dispersion effect is poor, leading to agglomeration of the composite material and affecting the performance of the coating slurry; if the ratio is too high, it may increase costs.

[0054] In one embodiment, the step of adding the PAN@C@LATP composite material and the dispersant to the solvent and mixing them thoroughly before the following steps are included:

[0055] An organic base and an acidic solution are added to a second solvent and allowed to react fully to obtain a buffer solution.

[0056] LATP powder and a carbon source were added to the buffer solution and allowed to react fully to obtain a polymer-modified LATP material.

[0057] The polymer-modified LATP material was carbonized to obtain a C@LATP composite material.

[0058] In this embodiment, an organic base and an acidic solution are added to a second solvent and allowed to react fully to obtain a buffer solution, which provides a stable pH environment for subsequent reactions. The buffer solution can resist the influence of external acids and bases to a certain extent, maintaining a relatively stable pH value. This ensures that the subsequently added LATP powder and carbon source react under suitable pH conditions, avoiding the impact of excessive pH fluctuations on the reaction process and product quality. LATP powder, as the main reactant, reacts with the carbon source in the specific environment of the buffer solution. The introduction of the carbon source is to form a porous carbon structure during the subsequent carbonization process. Through the reaction, the carbon source undergoes self-polymerization on the surface of the LATP powder, thereby polymerizing LATP. During carbonization, the polymer-modified layer undergoes pyrolysis and structural transformation under high temperature and other conditions, forming a polymer-derived porous carbon structure.

[0059] Specifically, in the buffer solution, the organic base and acidic solution can be tris(hydroxymethyl)aminomethane and hydrochloric acid solution, ethylenediamine and acetic acid solution, or diethanolamine and phosphoric acid solution. This application uses tris(hydroxymethyl)aminomethane and hydrochloric acid solution, and the second solvent is ultrapure water. The carbon source can be dopamine, pyrrole, aniline, or phenolic compounds. This application preferably uses dopamine. It is understood that dopamine contains abundant functional groups, such as hydroxyl (-OH) and amino (-NH-), which can form hydrogen bonds, ionic bonds, or covalent bonds with the surfaces of various materials, thereby allowing dopamine to firmly adhere to various substrate materials. In the preparation of battery separators, dopamine can adhere well to the surface of the base film, ensuring the stability of the coating layer, preventing the coating layer from falling off the base film during use, and ensuring the structural integrity and performance stability of the battery separator.

[0060] In one embodiment, after the step of carbonizing the polymer-modified LATP material to obtain the C@LATP composite material, the method further includes the following steps:

[0061] The C@LATP composite material was placed in a mixed gas of argon and oxygen for heating treatment.

[0062] In this embodiment, the above steps are used to optimize the carbon structure. In the heating environment of the mixed gas, argon, as an inert gas, provides a relatively stable atmosphere, preventing the C@LATP composite material from being over-oxidized at high temperatures or reacting unnecessarily with other impurities. Simultaneously, the presence of oxygen can moderately oxidize and adjust the carbon structure in the composite material. This oxidation can introduce specific functional groups, such as hydroxyl and carboxyl groups, onto the surface of the carbon material, thereby improving its surface chemical properties. These functional groups can increase the interaction between the carbon material and other components (such as PAN, electrolyte, etc.), improving the overall performance of the composite material. Heat treatment can promote further growth and refinement of the crystal structure in the C@LATP composite material, increasing its crystallinity. Higher crystallinity generally means better physical and chemical stability, as well as superior electrical properties. In battery separator applications, this helps improve the ion conductivity, thermal stability, and mechanical strength of the separator, thereby extending battery life and improving safety. By adjusting the ratio of argon and oxygen in the mixed gas, as well as parameters such as heating temperature and time, the performance of the C@LATP composite material can be precisely controlled. For example, different oxygen contents can lead to varying degrees of carbon oxidation, thus affecting the material's conductivity, hydrophilicity, and pore structure. This allows for the customized fabrication of composite materials with optimal performance based on specific application requirements.

[0063] In one embodiment, after the step of placing the C@LATP composite material in a mixed gas of argon and oxygen for heat treatment, the method further includes the following step:

[0064] The C@LATP composite material was dispersed in a third solvent to obtain a dispersion of the C@LATP composite material.

[0065] PAN powder is dissolved in a fourth solvent under a sealed environment to obtain a PAN solution;

[0066] The PAN solution was added to the dispersion and mixed thoroughly to obtain the PAN@C@LATP composite material.

[0067] In this embodiment, the third solvent uniformly disperses the C@LATP composite material therein, forming a stable dispersion system. The third solvent is ultrapure water, and the fourth solvent uniformly disperses the PAN powder therein. The fourth solvent includes toluene, dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF). N,N-dimethylacetamide is preferably used in this application.

[0068] Another embodiment of the present invention provides a lithium-ion battery comprising the separator described in any of the above claims.

[0069] The preparation process and performance of the present invention will be illustrated below with some specific examples.

[0070] Example 1:

[0071] Membrane preparation:

[0072] (1) Preparation of C@LATP composite material

[0073] Take 230 mg of tris(hydroxymethyl)aminomethane and add it to a reactor containing 110 ml of ultrapure water. Add 0.1 mol / L dilute hydrochloric acid dropwise to adjust the pH to 8.5 and then stop adding the hydrochloric acid. Stir the reaction for 40 min.

[0074] S1: LATP powder and 176 mg of dopamine hydrochloride were added to the reactor in sequence and stirred at room temperature for 12 h to obtain polydopamine-modified LATP;

[0075] S2: Under nitrogen as a protective gas, polydopamine-modified LATP was carbonized at 800 degrees Celsius for 180 min. After cooling to room temperature, it was placed in a tube furnace with an argon-oxygen volume ratio of 97.5:2.5 and reacted at 450 degrees Celsius for 1.5 h. After cooling to room temperature, C@LATP composite material was obtained.

[0076] (2) Preparation of PAN@C@LATP composite material:

[0077] S1: Take 5.8g of C@LATP composite material and 250ml of ultrapure water and add them to a three-necked flask. Mix them under mechanical stirring at 1000rpm for 6h and then sonicate them at 45KHZ and 450w power for 12h to obtain a C@LATP composite material dispersion.

[0078] S2: Take 1.65g of PAN powder and add it to a reactor containing 12.5g of N,N-dimethylacetamide. Stir and mix at 750rpm for 6 hours in a sealed environment to obtain a PAN solution.

[0079] S3: Under the conditions of mechanical stirring speed of 1500 rpm, 50 kHz and ultrasonic vibration power of 450 W, the PAN solution was added to the C@LATP composite dispersion through a three-necked flask at a flow rate of 0.5 ml / min.

[0080] S4: After completely adding the PAN solution to the C@LATP composite dispersion, reduce the stirring speed to 500 rpm and continue stirring for 4 hours. Then, perform ultrasonic vibration at 45 kHz and 450 W power for 5 hours to obtain the mixture.

[0081] S5: Centrifuge the mixture at 12000 rpm for 20 min, filter, wash, and dry at 0.08 MPa vacuum and 60 degrees Celsius for 48 h to obtain the PAN@C@LATP composite material.

[0082] (3) Preparation of PAN@C@LATP composite coating slurry:

[0083] S1: 18% by mass of PAN@C@LATP composite material and 0.85% by mass of hydrolyzed polymaleic anhydride were added to ultrapure water and premixed at 1600 rpm for 180 min; 0.8% by mass of sodium carboxymethyl cellulose was added and stirred at 1000 rpm for 120 min; 1.35% by mass of polyacrylic acid was added and stirred at 800 rpm for 150 min; 0.7% by mass of silanol nonionic surfactant was added and stirred at 750 rpm for 90 min. The above slurry was filtered and iron was removed to obtain PAN@C@LATP composite material coating slurry.

[0084] (4) Preparation of battery separator modified with PAN@C@LATP composite material:

[0085] S1: Using a micro-gravure roller coating process, the PAN@C@LATP composite material coating slurry is uniformly roller-coated onto the substrate using a coating machine. After baking in a 75℃ oven, it is rolled up for later use, thus obtaining the battery separator modified with PAN@C@LATP composite material for lithium-ion batteries.

[0086] Example 2:

[0087] The only difference between this embodiment and Embodiment 1 is that the mass ratio of PAN@C@LATP composite material added is 28%.

[0088] Example 3:

[0089] The only difference between this embodiment and Embodiment 1 is that the mass ratio of the PAN@C@LATP composite material added is 38%.

[0090] Example 4:

[0091] Membrane preparation:

[0092] (1) Preparation of C@LATP composite material

[0093] Take 230 mg of tris(hydroxymethyl)aminomethane and add it to a reactor containing 110 ml of ultrapure water. Add 0.1 mol / L dilute hydrochloric acid dropwise to adjust the pH to 8.5 and then stop adding the hydrochloric acid. Stir the reaction for 40 min.

[0094] S1: LATP powder and 176 mg of dopamine hydrochloride were added to the reactor in sequence and stirred at room temperature for 12 h to obtain polydopamine-modified LATP;

[0095] S2: Under nitrogen as a protective gas, polydopamine-modified LATP was carbonized at 800 degrees Celsius for 180 min. After cooling to room temperature, it was placed in a tube furnace with an argon-oxygen volume ratio of 97.5:2.5 and reacted at 450 degrees Celsius for 1.5 h. After cooling to room temperature, C@LATP composite material was obtained.

[0096] (2) Preparation of PAN@C@LATP composite material:

[0097] S1: Take 5.8g of C@LATP composite material and 250ml of ultrapure water and add them to a three-necked flask. Mix them under mechanical stirring at 1000rpm for 6h and then sonicate them at 45KHZ and 450w power for 12h to obtain a C@LATP composite material dispersion.

[0098] S2: Take 1.65g of PAN powder and add it to a reactor containing 12.5g of N,N-dimethylacetamide. Stir and mix at 750rpm for 6 hours in a sealed environment to obtain a PAN solution.

[0099] S3: Under the conditions of mechanical stirring speed of 1500 rpm, 50 kHz and ultrasonic vibration power of 450 W, the PAN solution was added to the C@LATP composite dispersion through a three-necked flask at a flow rate of 0.5 ml / min.

[0100] S4: After completely adding the PAN solution to the C@LATP composite dispersion, reduce the stirring speed to 500 rpm and continue stirring for 4 hours. Then, perform ultrasonic vibration at 45 kHz and 450 W power for 5 hours to obtain the mixture.

[0101] S5: Centrifuge the mixture at 12000 rpm for 20 min, filter, wash, and dry at 0.08 MPa vacuum and 60 degrees Celsius for 48 h to obtain the PAN@C@LATP composite material.

[0102] (3) Preparation of PAN@C@LATP composite coating slurry:

[0103] S31: Add 38% by mass of PAN@C@LATP composite material and 0.5% by mass of hydrolyzed polymaleic anhydride to ultrapure water and premix at 1600 rpm for 180 min; add 0.2% by mass of sodium carboxymethyl cellulose and continue stirring at 1000 rpm for 120 min; add 5% by mass of polyacrylic acid and continue stirring at 800 rpm for 150 min; add 0.1% by mass of silanol nonionic surfactant and continue stirring at 750 rpm for 90 min. Filter the above slurry and remove iron to obtain PAN@C@LATP composite material coating slurry.

[0104] (4) Preparation of battery separator modified with PAN@C@LATP composite material:

[0105] S1: Using a micro-gravure roller coating process, the PAN@C@LATP composite material coating slurry is uniformly roller-coated onto the substrate using a coating machine. After baking in a 75℃ oven, it is rolled up for later use, thus obtaining the battery separator modified with PAN@C@LATP composite material for lithium-ion batteries.

[0106] Example 5:

[0107] Membrane preparation:

[0108] (1) Preparation of C@LATP composite material

[0109] Take 230 mg of tris(hydroxymethyl)aminomethane and add it to a reactor containing 110 ml of ultrapure water. Add 0.1 mol / L dilute hydrochloric acid dropwise to adjust the pH to 8.5 and then stop adding the hydrochloric acid. Stir the reaction for 40 min.

[0110] S1: LATP powder and 176 mg of dopamine hydrochloride were added to the reactor in sequence and stirred at room temperature for 12 h to obtain polydopamine-modified LATP;

[0111] S2: Under nitrogen as a protective gas, polydopamine-modified LATP was carbonized at 800 degrees Celsius for 180 min. After cooling to room temperature, it was placed in a tube furnace with an argon-oxygen volume ratio of 97.5:2.5 and reacted at 450 degrees Celsius for 1.5 h. After cooling to room temperature, C@LATP composite material was obtained.

[0112] (2) Preparation of PAN@C@LATP composite material:

[0113] S1: Take 5.8g of C@LATP composite material and 250ml of ultrapure water and add them to a three-necked flask. Mix them under mechanical stirring at 1000rpm for 6h and then sonicate them at 45KHZ and 450w power for 12h to obtain a C@LATP composite material dispersion.

[0114] S2: Take 1.65g of PAN powder and add it to a reactor containing 12.5g of N,N-dimethylacetamide. Stir and mix at 750rpm for 6 hours in a sealed environment to obtain a PAN solution.

[0115] S3: Under the conditions of mechanical stirring speed of 1500 rpm, 50 kHz and ultrasonic vibration power of 450 W, the PAN solution was added to the C@LATP composite dispersion through a three-necked flask at a flow rate of 0.5 ml / min.

[0116] S4: After completely adding the PAN solution to the C@LATP composite dispersion, reduce the stirring speed to 500 rpm and continue stirring for 4 hours. Then, perform ultrasonic vibration at 45 kHz and 450 W power for 5 hours to obtain the mixture.

[0117] S5: Centrifuge the mixture at 12000 rpm for 20 min, filter, wash, and dry at 0.08 MPa vacuum and 60 degrees Celsius for 48 h to obtain the PAN@C@LATP composite material.

[0118] (3) Preparation of PAN@C@LATP composite coating slurry:

[0119] S31: Add 38% by mass of PAN@C@LATP composite material and 1.0% by mass of hydrolyzed polymaleic anhydride to ultrapure water and premix at 1600 rpm for 180 min; add 0.55% by mass of sodium carboxymethyl cellulose and continue stirring at 1000 rpm for 120 min; add 10% by mass of polyacrylic acid and continue stirring at 800 rpm for 150 min; add 0.4% by mass of silanol nonionic surfactant and continue stirring at 750 rpm for 90 min. Filter the above slurry and remove iron to obtain PAN@C@LATP composite material coating slurry.

[0120] (4) Preparation of battery separator modified with PAN@C@LATP composite material:

[0121] S1: Using a micro-gravure roller coating process, the PAN@C@LATP composite material coating slurry is uniformly roller-coated onto the substrate using a coating machine. After baking in a 75℃ oven, it is rolled up for later use, thus obtaining the battery separator modified with PAN@C@LATP composite material for lithium-ion batteries.

[0122] Example 6:

[0123] Membrane preparation:

[0124] (1) Preparation of C@LATP composite material

[0125] Take 230 mg of tris(hydroxymethyl)aminomethane and add it to a reactor containing 110 ml of ultrapure water. Add 0.1 mol / L dilute hydrochloric acid dropwise to adjust the pH to 8.5 and then stop adding the hydrochloric acid. Stir the reaction for 40 min.

[0126] S1: LATP powder and 176 mg of dopamine hydrochloride were added to the reactor in sequence and stirred at room temperature for 12 h to obtain polydopamine-modified LATP;

[0127] S2: Under nitrogen as a protective gas, polydopamine-modified LATP was carbonized at 800 degrees Celsius for 180 min. After cooling to room temperature, it was placed in a tube furnace with an argon-oxygen volume ratio of 97.5:2.5 and reacted at 450 degrees Celsius for 1.5 h. After cooling to room temperature, C@LATP composite material was obtained.

[0128] (2) Preparation of PAN@C@LATP composite material:

[0129] S1: Take 5.8g of C@LATP composite material and 250ml of ultrapure water and add them to a three-necked flask. Mix them under mechanical stirring at 1000rpm for 6h and then sonicate them at 45KHZ and 450w power for 12h to obtain a C@LATP composite material dispersion.

[0130] S2: Take 1.65g of PAN powder and add it to a reactor containing 12.5g of N,N-dimethylacetamide. Stir and mix at 750rpm for 6 hours in a sealed environment to obtain a PAN solution.

[0131] S3: Under the conditions of mechanical stirring speed of 1500 rpm, 50 kHz and ultrasonic vibration power of 450 W, the PAN solution was added to the C@LATP composite dispersion through a three-necked flask at a flow rate of 0.5 ml / min.

[0132] S4: After completely adding the PAN solution to the C@LATP composite dispersion, reduce the stirring speed to 500 rpm and continue stirring for 4 hours. Then, perform ultrasonic vibration at 45 kHz and 450 W power for 5 hours to obtain the mixture.

[0133] S5: Centrifuge the mixture at 12000 rpm for 20 min, filter, wash, and dry at 0.08 MPa vacuum and 60 degrees Celsius for 48 h to obtain the PAN@C@LATP composite material.

[0134] (3) Preparation of PAN@C@LATP composite coating slurry:

[0135] S31: Add 38% by mass of PAN@C@LATP composite material and 1.5% by mass of hydrolyzed polymaleic anhydride to ultrapure water and premix at 1600 rpm for 180 min; add 0.9% by mass of sodium carboxymethyl cellulose and continue stirring at 1000 rpm for 120 min; add 15% by mass of polyacrylic acid and continue stirring at 800 rpm for 150 min; add 0.7% by mass of silanol nonionic surfactant and continue stirring at 750 rpm for 90 min. Filter the above slurry and remove iron to obtain PAN@C@LATP composite material coating slurry.

[0136] (4) Preparation of battery separator modified with PAN@C@LATP composite material:

[0137] S1: Using a micro-gravure roller coating process, the PAN@C@LATP composite material coating slurry is uniformly roller-coated onto the substrate using a coating machine. After baking in a 75℃ oven, it is rolled up for later use, thus obtaining the battery separator modified with PAN@C@LATP composite material for lithium-ion batteries.

[0138] Comparative Example 1:

[0139] (1) Preparation of C@LATP composite material

[0140] S1: Take 230 mg of tris(hydroxymethyl)aminomethane and add it to a reactor containing 110 ml of ultrapure water. Add 0.1 mol / L dilute hydrochloric acid dropwise to adjust the pH to 8.5 and then stop adding the acid. Stir the reaction for 40 min.

[0141] S2: LATP powder and 176 mg of dopamine hydrochloride were added to the reactor in sequence and stirred at room temperature for 12 h to obtain polydopamine-modified LATP.

[0142] S3: Under nitrogen as a protective gas, polydopamine-modified LATP was carbonized at 800 degrees Celsius for 180 min. After cooling to room temperature, it was placed in a tube furnace with an argon-oxygen volume ratio of 97.5:2.5 and reacted at 450 degrees Celsius for 1.5 h. After cooling to room temperature, C@LATP composite material was obtained.

[0143] (2) Preparation of C@LATP composite coating slurry:

[0144] S1: 38% by mass of C@LATP composite material and 0.85% by mass of hydrolyzed polymaleic anhydride were added to ultrapure water and premixed at 1600 rpm for 180 min; 0.8% by mass of sodium carboxymethyl cellulose was added and stirred at 1000 rpm for 120 min; 1.35% by mass of polyacrylic acid was added and stirred at 800 rpm for 150 min; 0.7% by mass of silanol nonionic surfactant was added and stirred at 750 rpm for 90 min. The above slurry was filtered and iron was removed to obtain C@LATP composite material coating slurry.

[0145] (3) Preparation of battery separator modified with C@LATP composite material:

[0146] S1: Using a micro-gravure roller coating process, the C@LATP composite material coating slurry is uniformly roller-coated onto the substrate using a coating machine. After baking in a 75℃ oven, it is rolled up for later use, thus obtaining the battery separator modified with C@LATP composite material for lithium-ion batteries.

[0147] Comparative Example 2:

[0148] (1) Preparation of PAN@LATP composite material:

[0149] S1: Add 5.8g of LATP material and 250ml of ultrapure water to a three-necked flask, mix for 6 hours with mechanical stirring at 1000rpm, and then sonicate at 45KHZ and 450w power for 12 hours to obtain LATP material dispersion.

[0150] S2: Take 1.65g of PAN powder and add it to a reactor containing 12.5g of N,N-dimethylacetamide. Stir and mix at 750rpm for 6 hours in a sealed environment to obtain a PAN solution.

[0151] S3: Under the conditions of mechanical stirring speed of 1500 rpm, 50 kHz and ultrasonic vibration power of 450 W, the PAN solution was added to the LATP dispersion through a three-necked flask at a flow rate of 0.5 ml / min.

[0152] S4: Completely add the PAN solution to the LATP dispersion, reduce the stirring speed to 500 rpm, continue stirring for 4 hours, and then perform ultrasonic vibration at 45 kHz and 450 W power for 5 hours to obtain the mixture;

[0153] S5: The mixture was then centrifuged at 12,000 rpm for 20 min, filtered, washed, and dried at 0.08 MPa vacuum and 60 degrees Celsius for 48 h to obtain the PAN@LATP composite material.

[0154] (2) Preparation of PAN@LATP composite coating slurry:

[0155] S1: Add 38% by mass of PAN@LATP composite material and 0.85% by mass of hydrolyzed polymaleic anhydride to ultrapure water and premix at 1600 rpm for 180 min; add 0.8% by mass of sodium carboxymethyl cellulose and continue stirring at 1000 rpm for 120 min; add 1.35% by mass of polyacrylic acid and continue stirring at 800 rpm for 150 min; add 0.7% by mass of silanol nonionic surfactant and continue stirring at 750 rpm for 90 min. Filter the above slurry and remove iron to obtain PAN@LATP composite material coating slurry.

[0156] (3) Preparation of battery separator modified with PAN@LATP composite material:

[0157] S1: Using a micro-gravure roller coating process, the PAN@LATP composite material coating slurry is uniformly roller-coated onto the substrate using a coating machine. After baking in a 75℃ oven, it is rolled up for later use, thus obtaining the battery separator modified with PAN@LATP composite material for lithium-ion batteries.

[0158] Comparative Example 3:

[0159] The only difference between this comparative example and Example 1 is that this comparative example only has a base film, and the polyolefin separator described above is used as a comparison, without a coating layer.

[0160] Comparative Example 4: No PAN@C@LATP composite material was prepared or added; all other aspects were the same as in Example 1. Details are as follows:

[0161] (3) Preparation of coating slurry:

[0162] S1: Add 1.5% by mass of hydrolyzed polymaleic anhydride to ultrapure water and premix at 1600 rpm for 180 min; add 0.9% by mass of sodium carboxymethyl cellulose and continue stirring at 1000 rpm for 120 min; add 15% by mass of polyacrylic acid and continue stirring at 800 rpm for 150 min; add 0.7% by mass of silanol nonionic surfactant and continue stirring at 750 rpm for 90 min. Filter the above slurry and remove iron to obtain the coating slurry.

[0163] (4) Preparation of battery separator:

[0164] S1: Using a micro-gravure roller coating process, the coating slurry is evenly roller-coated onto the substrate by a coating machine. After baking in a 75℃ oven, it is rolled up for later use, thus obtaining the battery separator for lithium-ion batteries to be prepared.

[0165] Testing: The membranes prepared in the above examples and comparative examples were subjected to performance tests according to the testing standard GB / T36363-2018. The peel strength was tested using a universal testing machine, and the air permeability was tested using a Gurley air permeability meter. The data obtained are shown in the table below:

[0166] Table 1. Results of diaphragm air permeability, peel strength, and heat shrinkage tests.

[0167]

[0168] The following conclusions can be drawn from Table 1:

[0169] Compared with Comparative Examples 1 to 4, the air permeability test results of Examples 1 to 6 show that the air permeability values ​​of Examples 1 to 6 are all lower than those of Comparative Examples 1 and 2, and higher than those of Comparative Examples 3 and 4. This indicates that in these examples, the membrane structure formed by the PAN@C@LATP composite material is relatively compact and uniform. The interaction between its particles and with other additives makes the diffusion path of gas molecules in the membrane relatively complex, thus resulting in lower air permeability values ​​and better air permeability compared to Comparative Examples 1 and 2. In Comparative Example 1, only the membrane of the C@LATP composite material and in Comparative Example 2, the membrane of the PAN@LATP composite material have a relatively compact and uniform structure compared to the PAN@C@LATP composite material. A more porous structure or a higher number of pores allows gas molecules to pass through more easily, resulting in a higher permeability value and relatively poorer permeability performance. Comparative Example 3 has no coating layer, and its porous base membrane is not conducive to gas barrier, so its permeability value is very low. Comparative Example 4 lacks a core-shell structure but still has a coating layer, so its permeability value is higher than that of Comparative Example 3, and even higher than that of Examples 1 to 6. Furthermore, as can be seen from Examples 1 to 3, when the mass ratio of the core-shell structure PAN@C@LATP in the slurry increases from 18% to 38%, the permeability value increases sequentially, and the permeability performance deteriorates. As can be seen from Examples 3 to 6, the mass ratio of PAN@C@LATP in the slurry is the main factor affecting the permeability value of the membrane.

[0170] Compared with Comparative Examples 1 to 4, the anodic-hot-press peel test results of Examples 1 to 6 show that the peel force values ​​of Examples 1 to 6 are significantly improved compared with Comparative Examples 1 to 4. Furthermore, as the content of PAN@C@LATP composite material gradually increases from 18% to 38%, the peel strength of the corresponding diaphragm coating increases. This indicates that the PAN polymer chains in the PAN@C@LATP composite material can form better physical and chemical interactions with the electrode material, such as van der Waals forces and hydrogen bonds, thereby enhancing the adhesion between the diaphragm and the electrode and improving the anodic-hot-press peel force. In Comparative Example 1, the lack of PAN coating structure resulted in poor adhesion between the C@LATP composite material and the electrode. In Comparative Example 2, the structure of the PAN@LATP composite material was less effective in interacting with the electrode than that of the PAN@C@LATP composite material. In Comparative Example 4, the absence of the PAN@C@LATP composite material resulted in insufficient adhesion between other components in the slurry and the electrode, leading to a lower peel force.

[0171] Compared with Comparative Examples 1 to 4, the heat shrinkage rate test results of Examples 1 to 6 show that the heat shrinkage rate values ​​of Examples 1 to 6 are significantly lower than those of Comparative Examples 1 to 4. Furthermore, as the PAN@C@LATP composite material content gradually increases from 18% to 38%, the lower the corresponding coating heat shrinkage rate of the diaphragm, the better the heat shrinkage performance. This indicates that the presence of the PAN@C@LATP composite material can improve the thermal stability of the diaphragm. Under high-temperature conditions, the PAN polymer chains and the carbon layer and other structures in the C@LATP composite material can play a supporting and stabilizing role in the diaphragm structure, reducing heat shrinkage. Meanwhile, Examples 3 to 6, compared with Comparative Examples 1, 2, and 3... In contrast, the lack of effective PAN coating (Comparative Example 1), poor thermal stability of the structure itself (Comparative Example 2), or absence of a coating layer (Comparative Example 3) all lead to easy thermal shrinkage of the diaphragm at high temperatures, further proving that PAN can reduce the thermal shrinkage rate. Compared with PAN@LATP composite material, the carbon-based composite material has a synergistic effect with PAN and LATP, which can enhance the thermal stability of the composite material. This confirms the effectiveness of the core-shell structure of PAN@C@LATP in improving heat resistance and that PAN, LATP and carbon-based components can work synergistically to improve the thermal shrinkage performance of the diaphragm.

[0172] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A battery separator, characterized in that, It includes a base film and a coating layer; the coating layer includes a PAN@C@LATP composite material; The carbon matrix in the PAN@C@LATP composite material is polymer-derived porous carbon; The preparation of C@LATP includes: adding an organic base and an acidic solution to a second solvent and reacting them fully to obtain a buffer solution; adding LATP powder and a carbon source to the buffer solution and reacting them fully to obtain a polymer-modified LATP material; and carbonizing the polymer-modified LATP material to obtain a C@LATP composite material, wherein the carbon source includes dopamine, pyrrole, aniline, or phenolic compounds.

2. The battery separator according to claim 1, characterized in that, The coating layer also includes dispersants, thickeners, binders, and wetting agents.

3. The battery separator according to claim 2, characterized in that, The dispersant is any one of hydrolyzed polymaleic anhydride, lauramide, polyethylene wax, and ethyl acetate; the thickener is any one of sodium hydroxymethyl cellulose, hydroxyethyl cellulose, and methyl cellulose; and the binder is any one of polyacrylic acid, polyacrylamide, and polyvinyl alcohol.

4. The battery separator according to claim 2, characterized in that, The wetting agent is a silanol nonionic surfactant.

5. The battery separator according to claim 1, characterized in that, The base membrane is a porous thin film.

6. A method for preparing a battery separator, characterized in that, The method for preparing the battery separator as described in any one of claims 1 to 5 includes the following steps: The PAN@C@LATP composite material and dispersant were added to the first solvent and mixed thoroughly. Thickener, binder, and wetting agent are added and mixed evenly to obtain the coating slurry of PAN@C@LATP composite material; The coating slurry is uniformly coated onto the base film, and after drying, the battery separator is obtained.

7. The method for preparing the battery separator according to claim 6, characterized in that, The components of the coating slurry, by weight fraction, are: PAN@C@LATP composite material 18%~38%, thickener 0.2%~1.0%, binder 0.3%~1.7%, wetting agent 0.05%~0.55%, dispersant 0.1%~1.0%, and the remainder is the first solvent.

8. The method for preparing the battery separator according to claim 6, characterized in that, After the step of carbonizing the polymer-modified LATP material to obtain the C@LATP composite material, the method further includes the following steps: The C@LATP composite material was placed in a mixed gas of argon and oxygen for heating treatment.

9. The method for preparing the battery separator according to claim 8, characterized in that, Following the step of placing the C@LATP composite material in a mixed gas of argon and oxygen for heat treatment, the method further includes the following steps: The C@LATP composite material was dispersed in a third solvent to obtain a dispersion of the C@LATP composite material. PAN powder is dissolved in a fourth solvent under a sealed environment to obtain a PAN solution; The PAN solution was added to the dispersion and mixed thoroughly to obtain the PAN@C@LATP composite material.

10. A lithium-ion battery, characterized in that, Includes the diaphragm as described in any one of claims 1 to 5.

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