CN115207559A - High-performance aramid fiber diaphragm and preparation method and application thereof - Google Patents

High-performance aramid fiber diaphragm and preparation method and application thereof Download PDF

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CN115207559A
CN115207559A CN202210740784.6A CN202210740784A CN115207559A CN 115207559 A CN115207559 A CN 115207559A CN 202210740784 A CN202210740784 A CN 202210740784A CN 115207559 A CN115207559 A CN 115207559A
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aramid
aramid fiber
fiber
diaphragm
performance
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CN115207559B (en
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陈克复
李金鹏
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F1/00—General methods for the manufacture of artificial filaments or the like
    • D01F1/02—Addition of substances to the spinning solution or to the melt
    • D01F1/10—Other agents for modifying properties
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/88—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds
    • D01F6/90—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds of polyamides
    • D01F6/905—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds of polyamides of aromatic polyamides
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
    • D21H13/10—Organic non-cellulose fibres
    • D21H13/20—Organic non-cellulose fibres from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H13/26—Polyamides; Polyimides
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H15/00—Pulp or paper, comprising fibres or web-forming material characterised by features other than their chemical constitution
    • D21H15/02—Pulp or paper, comprising fibres or web-forming material characterised by features other than their chemical constitution characterised by configuration
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/44—Fibrous material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Electrochemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Textile Engineering (AREA)
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Abstract

The invention discloses a high-performance aramid fiber diaphragm and a preparation method and application thereof, wherein the preparation method comprises the following steps: (1) pretreating aramid fibers: taking differential aramid chopped fibers and differential aramid fibrids as raw materials, and mechanically pretreating the raw materials to prepare an aramid fiber mixed dispersion liquid; and (2) aramid fiber diaphragm manufacturing: adjusting the concentration of the aramid fiber dispersion liquid, and then performing wet papermaking by using an inclined wire former to obtain an aramid fiber diaphragm base material; (3) hot pressing treatment: and (3) directly carrying out hot press molding on the prepared aramid fiber diaphragm base material to finally prepare the high-performance aramid fiber diaphragm. The high-performance aramid fiber diaphragm provided by the invention is simple and convenient in production process, has excellent mechanical properties and high-temperature resistance, has adjustable pore structure and liquid absorption rate, is convenient to match with the actual working scene requirements of energy battery diaphragms and is suitable for industrial expanded production, and can be widely used as a high-performance lithium ion battery diaphragm.

Description

High-performance aramid fiber diaphragm and preparation method and application thereof
Technical Field
The invention belongs to the field of lithium ion batteries, and particularly relates to a high-performance aramid fiber diaphragm and a preparation method and application thereof.
Background
As an important component of the lithium battery, the diaphragm plays a key role in the safety performance of the lithium battery, can effectively avoid direct contact of positive and negative electrode materials, and has obvious influence on the high and low temperature performance, the cycling stability and the like of the battery. Therefore, the research and exploration of the novel high-performance diaphragm are of great significance to the development of high-performance and high-safety lithium ion batteries.
At present, the preparation process of the battery diaphragm is mainly divided into a dry method (melt drawing), a wet method (thermally induced phase separation, non-solvent induced phase separation), an electrostatic spinning method and the like. The polyolefin diaphragm is mainly prepared by a dry method and a wet method, and the high polymer diaphragm such as meta-aramid, polyimide and the like is mainly prepared by an electrostatic spinning method. For example, chinese patents 202080056546.2, 201880071194.0 and 202010596751.X disclose methods for preparing polyolefin separators, but when the operating temperature exceeds 130 ℃ or more, the shrinkage and the loss of mechanical properties of the separator are severe, which may seriously affect the safe use of the battery. Also, commercial polyolefin separators (PP, PE) suffer from poor thermal stability, poor wettability, and relatively single functionality, resulting in rapid capacity fade at high rates. In the cycle use, the electrode material (cathode lithium metal) forms a large amount of lithium dendrites due to uneven lithium ion deposition, continuously grows along with the cycle use of the battery, directly pierces the diaphragm, reduces the battery capacity, causes internal short circuit for a long time, greatly shortens the service life of the battery and causes safety problems. In order to improve the performance of the polyolefin separator, a plurality of researchers have researched the problems and put forward a plurality of solutions, such as surface modification of inorganic nanoparticles (such as Al) 2 O 3 、SiO 2 Surface grafting, surface polymer coating and the like, so as to improve the heat resistance of the diaphragm and the wettability of the diaphragm to liquid electrolyte, and improve the circulation stability and rate capability. For example, chinese patent 201110379586.3 manufactures a nano ceramic material coating on the surface of a polyolefin microporous film, improves the high-temperature thermal stability of a lithium ion battery, and improves the safety and reliability of the lithium ion battery, but this undoubtedly increases the difficulty in manufacturing a separator. On the other hand, the polyolefin material is generally a non-polar material, such as a PP film with a surface contact angle close to 90 ° and strong hydrophobicity, and the water absorption after being coated and modified by an inorganic coating is improved, so that the contact angle of the electrolyte can be reduced to about 65 ° to a certain extent, but the energy consumption of a drying link in the production and assembly process of the lithium ion battery is also increased significantly, and the cost is increased (liwenjun, et al, a high energy density lithium battery development strategy, 2020,9, 448-478. Furthermore, chinese patent 201410188353.9 discloses a method for preparing a battery diaphragm composed of aramid fibers by an ultrasonic dispersion method, wherein the battery diaphragm with a porosity of 60-80% is prepared, on one hand, the ultrasonic dispersion effect is limited, and the industrialization difficulty is large, and on the other hand, too high porosity directly causes the reduction of mechanical strength and puncture resistance strength, and the strength requirement of the diaphragm cannot be met. In addition, the non-woven fabric method has attracted more and more attention in recent years, and although the preparation process is simple, the porosity is high, the pore size distribution is uniform, and the micropores present a three-dimensional structure, the requirements of the lithium ion battery on the pore size and the thickness of the diaphragm cannot be met at the same time.
So far, a wet papermaking method is adopted to prepare a high-performance aramid fiber diaphragm-based material suitable for practical application. The diameter of the fiber of the lithium ion battery diaphragm is required to be in submicron or several micron scale, otherwise, the requirements of the diaphragm aperture and thickness are difficult to meet simultaneously. At present, the diameter of the commercial aramid fiber is generally between ten microns and tens of microns, and the requirement for producing aramid fiber membranes is difficult to meet. Chinese patent CN 104577011A discloses a battery diaphragm reinforcing material, which mainly comprises the steps of pulping and batching, papermaking and forming, drying, high-temperature hot rolling and the like. Because of the forming stage of papermaking, the cylinder forming is adoptedResulting in a reduction in the mechanical properties of the material. In addition, the technology adopts the aramid fiber with the fineness of 1.2-3.2 dtex according to the aramid fiber density of 1.45g/cm 3 The diameter of the used fiber is calculated to be between 10.27 and 16.76 mu m, the final battery diaphragm is thicker (more than 30 mu m), and the standard requirement of the diaphragm cannot be met, for example, the diaphragm thickness limit specified by the national standard GBT 36363-2018 polyolefin diaphragm for lithium ion batteries is 16 mu m and 25 mu m. In addition, the high-temperature hot pressing is carried out, particularly after the temperature is higher than 280 ℃, the value is higher than the glass transition temperature of the meta-aramid, so that the combination of fibers in the diaphragm is more compact, the porosity is influenced, and the service performance of the battery is possibly influenced.
With the development of increasingly diversified, complicated, flexible and light electronic products, the requirement for battery diaphragm lightness and thinness is higher. In general, the thickness of a separator for a battery is as small as possible, and it is a future trend that the separator is thin and light. Low thickness separators are a trend in current battery separator materials. The separator occupies a small volume in the battery structure, but too thin affects the mechanical properties of the separator, and is easily punctured or torn, resulting in short circuit between electrodes, thereby reducing the overall safety performance of the battery (Venugopal G, moore J, howard J, et al. Characterisation of microporosity separators for lithium-on batteries [ J ]. Journal of Power Sources,1999,77 (1): 34-41.). Therefore, the preparation of thin and high-mechanical-property diaphragm materials is a technical difficulty in the preparation of the current high-performance diaphragms. It is known that the development of high performance separator manufacturing techniques is urgently needed to advance the development of the battery separator technology field.
Aiming at the problems in the technical development of the lithium battery diaphragm, the uniform and efficient preparation of the high-performance aramid diaphragm is the bottleneck of the prior art on the premise of ensuring proper porosity and high liquid absorption rate. The technical scheme develops a novel diaphragm in the lithium ion battery diaphragm, and helps to improve the electrochemical performance and safety of the lithium ion battery.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention mainly aims to provide the high-performance aramid fiber membrane so as to improve the electrochemical performance and safety of the lithium ion battery. The membrane has excellent mechanical property and high-temperature resistance, and the pore structure and the liquid absorption rate of the aramid fiber membrane can be regulated and controlled, so that the membrane is convenient to match the actual working scene requirements of the energy battery membrane and is convenient for industrial expanded production.
The invention also aims to provide a preparation method of the high-performance aramid fiber membrane, which is simple and convenient in production process.
The invention further aims to provide application of the high-performance aramid fiber membrane in a lithium ion battery.
The purpose of the invention is realized by the following technical scheme:
a preparation method of a high-performance aramid fiber membrane comprises the following steps:
(1) Pretreating aramid fibers: taking differential aramid chopped fibers and differential aramid fibrids as raw materials, mixing the raw materials, and then carrying out mechanical pretreatment (or respectively carrying out mechanical pretreatment and then mixing the raw materials to prepare an aramid fiber mixed dispersion liquid; the differential aramid chopped fibers are aramid fibers with the average diameter less than or equal to 10 mu m, and the differential aramid fibrids are aramid fibers with the average thickness less than or equal to 500nm;
(2) Manufacturing aramid fiber diaphragms by papermaking: adjusting the concentration of the aramid fiber mixed dispersion liquid, and then carrying out wet papermaking by using an inclined wire former to obtain an aramid fiber diaphragm base material;
(3) Hot pressing treatment: and (3) directly carrying out hot press molding on the prepared aramid fiber diaphragm base material to finally prepare the high-performance aramid fiber diaphragm.
Preferably, the differential aramid chopped fibers in the step (1) are aramid fibers with the diameter of 2-10 microns and the length of 3-20 mm; the aramid fibrid is aramid fibrid with width of 2-20 μm, length of 0.5-5 mm and average thickness of less than or equal to 200 nm.
Preferably, the differential aramid chopped fibers in the step (1) are aramid fibers with the diameter of 2-8 microns and the length of 10-20 mm; the aramid fibrid has a width of 5-10 μm, a length of 3-5 mm, and an average thickness of less than or equal to 150nm.
Preferably, the aramid fiber dispersion liquid is homogenized and rectified before the upper net in the step (2), so that the fibers are dispersed by full turbulence.
Preferably, single-helix hole-row type, double-helix hole-row type hole rollers, sheet rollers or rod rollers are adopted for homogenizing and rectifying in the step (2); the concentration of the upper wire formed by the inclined wire is 0.01-0.08%.
Preferably, the mass ratio of the aramid fibrid to the aramid chopped fiber in the step (1) is (1-99) to (99-1); in the step (2), the concentration of the aramid fiber mixed dispersion liquid is 0.01-0.5%.
Preferably, the mass ratio of the aramid fibrid to the aramid chopped fiber in the step (1) is (10-90) to (90-10); the concentration of the aramid fiber mixed dispersion liquid in the step (2) is 0.01-0.10%.
Preferably, the aramid fiber in step (1) is of a type of at least one of wholly aromatic polyamide fiber or heterocyclic aromatic polyamide fiber; the mechanical pretreatment is pre-pulping treatment by a disc grinder to obtain SR aramid fiber dispersion liquid with the pulping degree of 50-85 degrees.
Preferably, a dispersant is further added in the step (2), wherein the dispersant is one or more of N-methyl pyrrolidone, methoxy polyethylene glycol, polyethylene glycol dimethyl ether, polyethylene oxide, polyacrylamide and sodium polyacrylate, and the addition amount of the dispersant accounts for 0.01-2% of the mass of the aramid fiber.
Preferably, the hot press molding conditions in the step (3) are that the temperature is 100-260 ℃, the pressure is 0.1-20 MPa, and the time is 0.1-24 h.
The high-performance aramid fiber membrane prepared by the method has the thickness of below 25 mu m, the porosity of 40-70%, the liquid absorption rate of above 350%, the longitudinal tensile strength of above 90MPa, the transverse tensile strength of above 85MPa, and the puncture strength of above 450 g/mil; preferably, the film has a thickness of 10 to 25 μm, a porosity of 40 to 70%, a liquid absorption rate of 460% or more, a longitudinal tensile strength of 135MPa or more, a transverse tensile strength of 125MPa or more, and a puncture strength of 620g/mil or more. More preferably, the thickness is 14 to 22 μm, the porosity is 55 to 65%, the liquid absorption rate is 460 to 750%, the longitudinal tensile strength is 135 to 200MPa, the transverse tensile strength is 125 to 200MPa, and the puncture strength is 620 to 750g/mil.
The preparation process of the aramid fiber raw material comprises the following steps: the m-phenylenediamine and the isophthaloyl dichloride (the molar ratio is 100: 90-120) are prepared by a one-step low-temperature (0-20 ℃) polycondensation reaction. Specifically, dissolving a cosolvent and m-phenylenediamine in N, N-dimethylacetamide under the conditions of low temperature (0-20 ℃) and nitrogen protection atmosphere, then adding m-phthaloyl chloride in a fractional manner, gradually raising the temperature along with the reaction, carrying out heat preservation (50-90 ℃) treatment, and then adding an alkaline agent for neutralization to prepare a neutral aramid polymer solution; then adding a proper amount of modifier (10-40%) into the neutral aramid polymer, fully mixing and dispersing at a certain temperature (50-150 ℃), filtering, and removing bubbles to obtain the polymer blend liquid.
Preparing superfine aramid fibers: and conveying the obtained polymer blend to a spinneret plate, and carrying out spinning, solidification, drafting, washing, drying, heat setting and rolling in sequence to finally prepare the superfine aramid fiber.
Preparing aramid fibrid: and conveying the obtained polymer blend liquid to a precipitation device, carrying out diffusion and pre-curing on the polymer blend liquid by using a non-solvent, and carrying out multi-section washing on the polymer blend liquid after two-stage high shear action to finally obtain the strand-shaped precipitation fiber. The differential superfine aramid fiber and fibrid can be obtained by adjusting main process parameters such as the proportion of the aramid blend, the solidification condition, the drafting multiplying power, the shearing process and the like.
The sizes of the aramid chopped fibers, the aramid fibrids or the aramid pulp prepared by the conventional method are mostly dozens of microns or even larger, while the thicknesses of the commercial battery diaphragms are mostly porous films smaller than 25 microns, the diameters/thicknesses and the strengths of the fibers prepared by the conventional method can not meet the requirements, the battery diaphragms with moderate thicknesses and porosities are difficult to produce, and researchers are forced to search for fibers with the sizes of several microns or even smaller. The invention prepares the superfine aramid fiber and the fibrid based on the polymer modification technology, the size of the superfine aramid fiber and the fibrid is several microns or even smaller, a hole roller and the like are adopted to optimize a high-strength pulsating turbulent flow field, the superfine fiber raw material is promoted to be effectively turbulent and uniformly dispersed, a light and thin high-strength aramid fiber diaphragm is prepared by effectively combining an ultralow-concentration forming technology, the organic unification of the porosity, the thickness and the mechanical property of the aramid fiber diaphragm is cooperatively realized, and the use safety of a high-performance battery is ensured.
Compared with the prior art, the invention has the following advantages and effects:
according to the high-performance aramid fiber diaphragm disclosed by the invention, the distribution and interface combination effect of aramid fibers in the aramid fiber diaphragm base material are improved by performing surface modification on the aramid fibers, the surface pore structure of the aramid fiber diaphragm is optimized, the combination effect among the aramid fibers is effectively improved, and the advantage complementation of high mechanical strength and high porosity is realized. According to the invention, the aramid fiber is used as a basic raw material, the excellent mechanical property, temperature resistance and the like of the aramid fiber are utilized, the interface bonding effect of the fiber in the diaphragm is increased, the high-strength aramid diaphragm is prepared, and the manufacturing cost can be saved.
In addition, the method can easily realize the cooperative regulation and control of indexes such as the surface porosity, the liquid absorption rate, the puncture strength and the like of the aramid fiber membrane. The porosity is the ratio of the micropore volume to the whole volume of the membrane, and reflects the number of micropores of the membrane. Moreover, too high porosity directly leads to a decrease in mechanical strength and puncture resistance, failing to meet the strength requirements of the separator; too low porosity increases the internal resistance of ion transport, resulting in a decrease in the lithium ion transport efficiency of the battery. The aramid fiber diaphragm prepared by the invention has enough micropores to provide a storage space for electrolyte and reduce the conduction resistance of lithium ions between two electrodes. The porosity of the aramid fiber membrane prepared by the method is between 43.9% and 63.7%, and the aramid fiber membrane can be optimally regulated according to actual application scenes, so that the capacity retention rate of the battery is improved while the ion conduction capability of the battery is improved. And the differential aramid fiber is easy to form a microporous structure, so that a capillary effect is generated, and the effective absorption of the electrolyte is promoted. Because superfine aramid chopped fibers and differential aramid fibrids are fully mixed in the mechanical treatment process, the thinner aramid fibers are fully interwoven to form a large number of pore structures smaller than 1 micron, the fiber interface combination is improved, the good puncture strength is kept to a certain degree, and the use safety of the diaphragm is improved. Therefore, the invention also shows the technical effect of the cooperative regulation and control of the porosity and the puncture strength of the diaphragm.
In addition, the invention firstly uses the treated aramid differential fiber as a raw material, and adopts a hole roller and the like to optimize a high-strength pulsating turbulent flow field, so that the longer aramid fiber generates sufficient and effective turbulence in a sizing flow channel, and the fiber in the sizing flow is uniformly dispersed. In addition, the perforated rollers and the like can form a rectifying area of 'upstream and downstream' for the pulp flow to form strong turbulence, the depolymerization effect on the pulp flow is stronger, the flocculation of the slender aramid fiber is effectively avoided, the aramid fiber diaphragm with high porosity and liquid absorption rate is prepared by cooperating with the ultra-low concentration inclined net forming, and the improvement of the mechanical strength, the heat resistance, the wettability and the like of the diaphragm is cooperatively realized. The invention further optimizes the influence of different film forming/forming methods of the aramid fiber on the implementation effect of the diaphragm through experiments in the embodiment and the comparison example, and the technical implementation effect data shows that the effect is completely superior to the effect of the prior art.
Drawings
Fig. 1 is a flow chart of the preparation of a high-performance aramid membrane.
Fig. 2 is a sectional SEM image of the ultra-fine aramid fiber.
Fig. 3 is an SEM image of the surface of the aramid fibrid.
Fig. 4 is a SEM image of the surface of the high-performance aramid membrane.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.
The starting materials in the preparation method of the present invention can be obtained from commercial sources or prepared according to the prior art method, and the aramid fiber used in the embodiments of the present invention is a meta-aramid fiber, but is not limited to this manner.
Example 1
A preparation method of high-performance aramid fiber diaphragm comprises the following steps:
(1) Preparing an aramid polymer: dissolving m-phenylenediamine in N, N-dimethylacetamide under the conditions of low temperature of 5 ℃ and nitrogen protection atmosphere, adding calcium bromide, and then adding isophthaloyl chloride for 3 times, wherein the molar ratio of the m-phenylenediamine to the isophthaloyl chloride is controlled to be 100:103. the temperature is gradually increased to 80 ℃ as the reaction proceeds, and the holding time is 3h. After heat preservation treatment, adding calcium oxide for neutralization to prepare a neutral aramid polymer solution;
(2) Preparing aramid fiber stock solution: adding a proper amount of polyethylene glycol-800 into the neutral aramid polymer obtained in the step (1), wherein the oven dry mass ratio of the modifier to the aramid polymer is 30. Fully mixing, dispersing, filtering and defoaming to obtain a spinning stock solution;
(3) Preparing superfine aramid fibers: and (3) conveying the spinning solution obtained in the step (2) to a spinneret plate, and carrying out spinning, solidification, drafting, washing, drying, heat setting and rolling in sequence to finally prepare the superfine aramid fiber. The specific parameters are as follows, and the spinning process is as follows: the aperture range of the spinneret plate is 0.05mm, and the number of holes is 8000; the distance between the spinneret and the coagulation bath is 15cm; solidification, water washing and drafting: the first-stage coagulating bath comprises the following components in percentage by mass: n, N-dimethylacetamide: glycerol (b): water, etc = 70; the temperature of the coagulation bath is 70 ℃, and the drawing ratio is 1.6 times. The secondary coagulating bath comprises the following components in percentage by mass: n, N-dimethylacetamide: water =60 ℃, coagulation bath temperature is 70 ℃, and secondary coagulation bath draft ratio is 2.5 times. The water temperature of the first-stage washing is 40 ℃, and the drafting multiplying power is 1.5 times; the water temperature of the second-stage washing is 85 ℃. The drying temperature was 110 ℃. The hot drawing temperature is 285 ℃ and the drawing magnification is 2.9 times. The heat-setting temperature was 295 ℃.
The obtained aramid fiber is cut into fibers with the length of 6-20 mm according to the requirements of the embodiment, and the diameter of the superfine aramid fiber prepared in the embodiment is 3.0 μm through the test of a scanning electron microscope, and the SEM image of the cross section is shown in FIG. 2. The superfine aramid fibers with different diameters can be obtained by adjusting the main process parameters such as the proportion of the modifier to the aramid polymer, the distance between a spinneret plate and a coagulation bath, coagulation conditions, drafting multiplying power and the like.
Example 2
A preparation method of a high-performance aramid fiber diaphragm comprises the following steps:
(1) Preparing an aramid polymer: dissolving m-phenylenediamine in N, N-dimethylacetamide under the conditions of low temperature of 5 ℃ and nitrogen protection atmosphere, adding lithium chloride, and then adding isophthaloyl dichloride 3 times, wherein the molar ratio of the m-phenylenediamine to the isophthaloyl dichloride is controlled to be 100:103. the temperature is gradually increased to 80 ℃ as the reaction proceeds, and the holding time is 5h. After heat preservation treatment, adding calcium oxide for neutralization to prepare a neutral aramid polymer solution;
(2) Preparing an aramid fiber stock solution: adding a proper amount of polyethylene glycol-800 into the neutral aramid polymer obtained in the step (1), wherein the oven dry mass ratio of the modifier to the aramid polymer is 40. Filtering and defoaming after fully mixing and dispersing to obtain a precipitation stock solution;
(3) Preparing aramid fibrid: and (3) conveying the precipitation stock solution obtained in the step (2) to precipitation equipment, and sequentially carrying out two-stage high-speed shearing and multi-stage washing treatment to obtain aramid fibrids. The concrete process is as follows, in the first-stage high-speed shearing treatment process, the components and the mass ratio of the coagulating bath are as follows: n, N-dimethylacetamide: water =50, coagulation bath temperature 70 ℃, shear rate 7000rpm; in the second-stage high-speed shearing treatment process, the components and the mass ratio of the coagulating bath are as follows: n, N-dimethylacetamide: water =30, coagulation bath temperature 50 ℃, shear rate 8000rpm. And washing the aramid fiber in multiple stages to obtain the aramid fibrid.
The aramid fibrid prepared in this example has a width of about 15 μm, a length of about 4mm, a thickness of less than 200nm, and an original beating degree of 49 ° SR. The aramid fibrids with different size parameters can be obtained by adjusting main process parameters such as the proportion of the modifier to the aramid polymer, the solid content of the feeding blend, the solidification condition, the shearing rate and the like.
Example 3
A high-performance aramid fiber diaphragm is prepared by the following steps:
(1) Preparing aramid fiber raw materials: selecting differential aramid chopped and precipitated fibers as raw materials. Wherein the average length of the aramid chopped fibers is 6mm, and the average diameter of the aramid chopped fibers is 10.1 mu m; the aramid fibrid is in a sheet film shape, the average width of the aramid fibrid is 20 mu m, the average length of the aramid fibrid is 0.6mm, and the average thickness of the aramid fibrid is 200nm; the oven-dry mass ratio of the aramid fibrid to the aramid chopped fiber is 60. After being uniformly mixed, the mixture is subjected to pre-pulping treatment by a disc grinder to obtain differential aramid fiber pulp with the pulping degree of 50 degrees SR;
(2) Preparing an aramid fiber membrane substrate: the differential aramid fiber pulp is used as a raw material, methoxy polyethylene glycol is added as a dispersing agent, and the addition amount of the methoxy polyethylene glycol accounts for 2% of the total mass of the aramid fiber. And (3) before the wire is fed, a pore plate is adopted to homogenize slurry flow, the ultra-low concentration forming wet method is combined for papermaking, the wire feeding concentration during ultra-low concentration forming is 0.08%, and the aramid fiber diaphragm base material is obtained through drying and rolling.
(3) Preparing an aramid fiber membrane: selecting a certain amount of aramid fiber diaphragm base material, then carrying out hot pressing treatment under the conditions of 1MPa and 260 ℃, and carrying out hot pressing for 10min to obtain the high-performance aramid fiber diaphragm.
And (3) measuring the performance index of the aramid fiber membrane, and the test result is listed in table 1.
Example 4
A high-performance aramid fiber diaphragm is prepared by the following steps:
(1) Preparing aramid fiber raw materials: selecting differential aramid chopped and precipitated fibers as raw materials. Wherein the average length of the aramid chopped fibers is 10mm, and the average diameter of the aramid chopped fibers is 7.4 mu m; the aramid fibrid is in a sheet film shape, the average width of the aramid fibrid is 15 mu m, the average length of the aramid fibrid is 0.8mm, and the average thickness of the aramid fibrid is 160nm; the absolute dry mass ratio of the aramid fibrid to the aramid chopped fiber is 50. After being uniformly mixed, the mixture is subjected to pre-pulping treatment by a disc grinder to obtain differential aramid fiber pulp with the pulping degree of 67 DEG SR;
(2) Preparing an aramid fiber membrane substrate: the differential aramid fiber pulp is used as a raw material, N-methyl pyrrolidone is added as a dispersing agent, and the adding amount of the dispersing agent accounts for 0.01% of the total mass of the aramid fiber. And (3) homogenizing a pulp flow by adopting a double-helix line hole-array type hole roller before feeding, combining ultra-low concentration forming wet papermaking, wherein the ultra-low concentration forming feeding concentration is 0.05%, and drying and rolling to obtain the aramid fiber diaphragm base material.
(3) Preparing an aramid fiber membrane: selecting a certain amount of aramid fiber diaphragm base material, then carrying out hot pressing treatment under the conditions of 2MPa and 240 ℃, and carrying out hot pressing for 5min to obtain the high-performance aramid fiber diaphragm.
And (3) measuring the performance index of the aramid fiber membrane, and the test result is listed in table 1.
Example 5
A high-performance aramid fiber diaphragm is prepared by the following steps:
(1) Preparing aramid fiber raw materials: differential chopped aramid fiber and fibrid are selected as raw materials. Wherein the average length of the aramid chopped fibers is 20mm, and the average diameter of the aramid chopped fibers is 6.6 mu m; the aramid fibrid is in a sheet film shape, the average width of the aramid fibrid is 10 mu m, the average length of the aramid fibrid is 2.4mm, and the average thickness of the aramid fibrid is 130nm; the oven-dry mass ratio of the aramid fibrid to the aramid chopped fiber is 45. After being uniformly mixed, the mixture is subjected to pre-pulping treatment by a disc grinder to obtain differential aramid fiber pulp with the pulping degree of 72 DEG SR;
(2) Preparing an aramid fiber diaphragm base material: the differential aramid fiber pulp is used as a raw material, polyethylene glycol dimethyl ether is added as a dispersing agent, and the addition amount of the polyethylene glycol dimethyl ether accounts for 0.6% of the total mass of the aramid fiber. Before the web is fed, a sheet roller is adopted to homogenize the pulp flow, the ultra-low concentration forming wet method is combined for papermaking, the web feeding concentration in the ultra-low concentration forming process is 0.08%, and the aramid fiber diaphragm base material is obtained through drying and rolling.
(3) Preparing an aramid fiber membrane: selecting a certain amount of aramid fiber diaphragm base material, then carrying out hot pressing treatment under the conditions of 6MPa and 150 ℃, and carrying out hot pressing for 20min to obtain the high-performance aramid fiber diaphragm.
The performance indexes of the aramid fiber membranes were measured, and the test results are listed in table 1.
Example 6
A high-performance aramid fiber diaphragm is prepared by the following steps:
(1) Preparing aramid fiber raw materials: selecting differential aramid chopped and precipitated fibers as raw materials. Wherein the average length of the aramid chopped fibers is 12mm, and the average diameter of the aramid chopped fibers is 3.2 mu m; the aramid fibrid is in a sheet film shape, the average width of the aramid fibrid is 5 mu m, the average length of the aramid fibrid is 4.1mm, and the average thickness of the aramid fibrid is 100nm; the oven-dry mass ratio of the aramid fibrid to the aramid chopped fiber is 30. After being uniformly mixed, the mixture is subjected to pre-pulping treatment by a disc grinder to obtain differential aramid fiber pulp with the pulping degree of 82 degrees SR;
(2) Preparing an aramid fiber membrane substrate: the differential aramid fiber pulp is used as a raw material, polyethylene glycol dimethyl ether is added as a dispersing agent, and the addition amount of the polyethylene glycol dimethyl ether accounts for 0.8% of the total mass of the aramid fiber. Before the net feeding, single spiral line hole-arrangement type uniform pulp flow is adopted, the paper making is carried out by combining an ultra-low concentration forming wet method, the net feeding concentration in the ultra-low concentration forming is 0.01%, and the aramid fiber diaphragm base material is obtained through drying and rolling.
(3) Preparing an aramid fiber membrane: selecting a certain amount of aramid fiber diaphragm base material, then carrying out hot pressing treatment under the conditions of 10MPa and 220 ℃, and carrying out hot pressing for 5min to obtain the high-performance aramid fiber diaphragm.
The performance indexes of the aramid fiber membranes were measured, and the test results are listed in table 1. The surface pore structure of the prepared aramid fiber membrane is shown in fig. 3.
Example 7
This embodiment is different from embodiment 6 in that: in the step (1), the average width of the aramid fibrid is 10 μm, the average length is 2.4mm, and the average thickness is 130nm.
The performance indexes of the aramid fiber membranes were measured, and the test results are listed in table 1.
Example 8
This embodiment is different from embodiment 6 in that: in the step (1), the average length of the aramid chopped fibers is 10mm, and the average diameter of the aramid chopped fibers is 7.4 mu m.
The performance indexes of the aramid fiber membranes were measured, and the test results are listed in table 1.
Example 9
This embodiment is different from embodiment 6 in that: in the step (1), the treatment process of adopting single spiral line hole-array type uniform slurry flow before surfing the Internet is removed, and other conditions are unchanged.
The performance indexes of the aramid fiber membranes were measured, and the test results are listed in table 1. The uniformity of the prepared aramid fiber membrane is poor compared with that of the aramid fiber membrane prepared in the embodiment 6, and the mechanical property of the aramid fiber membrane is obviously reduced, which may be that the aramid fiber is not subjected to sufficient turbulent dispersion, so that part of the aramid fiber is agglomerated, and the mechanical property and the electrochemical property of the membrane are influenced.
Comparative example 1
An electrostatic spinning aramid fiber diaphragm is prepared by the following steps:
weighing 10% of aramid polymer by mass, and removing bubbles in vacuum to obtain a uniform solution; and transferring the solution into a 10ml syringe (the specification of a needle head is 18G), fixing the syringe on a laboratory injection pump, clamping an 18kV high-voltage power supply on the needle head, adjusting the height and the position of the needle head, wherein the propelling speed of the syringe is 1ml/h, the receiving distance is 15cm, so that the fibers can be sprayed to a target position, simultaneously coating an aluminum foil on a high-speed roller as a receiving device to collect the fibers, the rotating speed of the roller is 250r/min, the spinning temperature is regulated and controlled to be 25-30 ℃, and the relative humidity is 40-60%. Selecting a certain amount of aramid fiber diaphragm base material, then carrying out hot pressing treatment under the conditions of 2MPa and 150 ℃, and carrying out hot pressing for 10min to obtain the electrostatic spinning aramid fiber diaphragm.
Comparative example 2
The comparative example differs from example 5 in that: the papermaking mode in the step (2) is cylinder forming.
The performance indexes of the aramid fiber membranes were measured, and the test results are listed in table 1. Comparison with the data of example 5 shows that the same fiber material has a significantly reduced strength after cylinder papermaking and a significantly increased difference in strength in the longitudinal and transverse directions.
Comparative example 3
The preparation method of the aramid fiber membrane comprises the following steps:
(1) Preparing aramid fiber raw materials: the conventional chopped aramid fiber and fibrid are selected as raw materials. Wherein the average length of the aramid chopped fibers is 6mm, and the average diameter of the aramid chopped fibers is 15.8 mu m; the aramid fibrid is in a sheet film shape, the average width of the aramid fibrid is 100 mu m, the average length of the aramid fibrid is 0.8mm, and the average thickness of the aramid fibrid is more than 500nm; the oven-dry mass ratio of the aramid fibrid to the aramid chopped fiber is 50. After being uniformly mixed, the mixture is subjected to pre-pulping treatment by a disc grinder to obtain differential aramid fiber pulp with the pulping degree of 30 DEG SR;
(2) Preparing an aramid fiber membrane substrate: aramid fiber pulp is used as a raw material, a single spiral line arrangement type hole roller is adopted for homogenizing pulp flow before surfing, papermaking is carried out by combining an ultra-low concentration forming wet method, the net surfing concentration during ultra-low concentration forming is 0.05%, and the aramid fiber diaphragm base material is obtained through drying and rolling.
(3) Preparing an aramid fiber membrane: selecting a certain amount of aramid fiber diaphragm base material, then carrying out hot pressing treatment under the conditions of 2MPa and 240 ℃, and carrying out hot pressing for 20min to obtain the high-performance aramid fiber diaphragm.
The performance indexes of the aramid fiber membranes were measured, and the test results are listed in table 1.
Comparative example 4
The comparative example is different from comparative example 3 in that: and (3) replacing the ultra-low-consistency forming wet papermaking with a rotary screen forming wet papermaking under the papermaking condition in the step (2).
Comparative example 5
The comparative example differs from comparative example 4 in that:
in the step (1), the average width of the aramid fibrid is 15 μm, the average length is 0.8mm, and the average thickness is 160nm.
The performance indexes of the aramid fiber membranes were measured, and the test results are listed in table 1.
The detection method comprises the following steps: thickness (GB/T20628.2-2006); the tensile strength and the elongation at break are tested by a strip test sample method according to the regulations in GB/T29627.2-2013; measuring the water content according to GB/T29627.2-2013; thermal shrinkage ratio the separator was treated at 250 ℃ for 24 hours, and the percentage change in area after shrinkage (%) of the separator was recorded by photographing (a) = (b) 0 -A)/A 0 X100 formula, A o Refers to the initial area of the separator, and a is the final area of the separator after heat treatment. The liquid absorption rate measuring method comprises the following steps: and (3) putting the circular diaphragm with the diameter of 18mm into the lithium hexafluorophosphate electrolyte for soaking for 4 hours, and weighing the soaked mass. Liquid absorption rate = [ (M) 1 -M 0 )/M 0 ]X 100; in the formula, M 0 And M 1 The mass of the diaphragm before and after soaking in the electrolyte is unit g; puncture resistance is measured by reference to ASTM F1306-90; the porosity was measured by n-butanol imbibition: soaking a circular diaphragm with the diameter of 18mm in n-butanol solution for 4h, weighing the soaked mass, and calculating the porosity = [ (M) by adopting a formula 1 -M 0 )/ρV]×100，M 0 And M 1 The mass of the diaphragm before and after soaking in n-butyl alcohol is unit g; rho is the density of n-butanol and is 0.81g/cm 3 (ii) a V is the volume of the diaphragm in cm 3 (ii) a The ionic conductivity was calculated by measuring the bulk impedance of the simulated cell, the ionic conductivity = L/(R × a) where: l is the thickness of the diaphragm; a is the effective contact area of the diaphragm, and R is the bulk resistance (omega) of the diaphragm. Assembling the battery: in a glove box filled with argon, pressAnd assembling the positive electrode shell/the stainless steel sheet/the diaphragm/the stainless steel sheet/the negative electrode shell into a button battery in sequence, packaging, and standing for 12 hours to be tested. The cycle performance test of the battery is that the battery is charged and discharged for 100 times at a constant current of 0.5C, and the voltage ranges are as follows: 3.0V-4.2V, and the capacity after 100 times of test cycle is divided by the capacity of the first test to calculate the capacity retention rate (%).
Table 1 shows the mechanical property detection data of the high-performance aramid fiber membrane prepared in the example
Figure BDA0003717889300000141
As can be seen from Table 1, the indexes of the high-performance aramid fiber membrane are superior to those of the conventional membrane material. Since the pressure born by the diaphragm between the electrodes is larger, as can be seen from table 1, the thickness, strength and electrochemical performance indexes of the aramid paper prepared by adopting the aramid fiber with the conventional diameter are far higher than those of the aramid diaphragm prepared by adopting the superfine aramid fiber. The aramid fiber membrane prepared by the invention has excellent anti-puncture capability, and can effectively prevent the short circuit of a battery caused by the puncture of the membrane; on the other hand, the improvement of the puncture resistance of the separator helps to reduce the deformation degree of the pores of the separator to promote the uniform circulation of the Li + flow. As can be seen from FIG. 2, the aramid fibers used in the present invention have an average diameter of about 3 μm, and the bonding effect between the aramid fibers can be effectively increased during the forming process; as can be seen from FIG. 3, the aperture of the aramid fiber diaphragm prepared by the method is clear and visible, the aperture is formed by interlacing aramid fibers, and the aperture size is smaller than 1 μm. The aramid fiber diaphragm of the invention meets the requirement of effective unification of thickness, porosity and mechanical property of battery diaphragm materials. In conclusion, the invention adopts the high-strength pulsating turbulent flow field to promote the superfine fiber raw material to be effectively turbulent and uniformly dispersed, effectively combines the ultra-low concentration forming technology to prepare the light and thin high-strength aramid fiber diaphragm, synergistically realizes the organic unification of the porosity, the thickness and the mechanical property of the aramid fiber diaphragm, and ensures the use safety of the high-performance battery.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims (10)

1. A preparation method of a high-performance aramid fiber membrane is characterized by comprising the following steps:
(1) Pretreating aramid fibers: taking differential aramid chopped fibers and differential aramid fibrids as raw materials, and carrying out mechanical pretreatment on the raw materials to prepare an aramid fiber mixed dispersion liquid; the differential aramid chopped fibers are aramid chopped fibers with the average diameter less than or equal to 10 mu m, and the differential aramid fibrids are aramid fibrids with the average thickness less than or equal to 500nm;
(2) Manufacturing aramid fiber diaphragms by papermaking: adjusting the concentration of the aramid fiber mixed dispersion liquid, and then performing wet papermaking through an inclined wire former to obtain an aramid fiber diaphragm base material;
(3) Hot pressing treatment: and (3) directly carrying out hot press molding on the prepared aramid fiber diaphragm base material to finally prepare the high-performance aramid fiber diaphragm.
2. The production method according to claim 1, characterized in that: the differential aramid chopped fiber in the step (1) is aramid chopped fiber with the diameter of 2-10 mu m and the length of 3-20 mm; the aramid fibrid is 2-20 mu m wide, 0.5-5 mm long and less than or equal to 200nm in average thickness.
3. The method of claim 2, wherein: the diameter of the differential aramid chopped fiber in the step (1) is 2-8 mu m, and the length is 10-20 mm; the width of the aramid fibrid is 5-10 μm, the length is 3-5 mm, and the average thickness is less than or equal to 150nm.
4. The method of claim 1, wherein: the mass ratio of the aramid precipitated fiber to the aramid chopped fiber in the step (1) is (1-99) to (99-1); in the step (2), the concentration of the aramid fiber mixed dispersion liquid is 0.01-0.5%.
5. The method of claim 4, wherein: the mass ratio of the aramid precipitated fiber to the aramid chopped fiber in the step (1) is (10-90) to (90-10); the concentration of the aramid fiber mixed dispersion liquid in the step (2) is 0.01-0.10%.
6. The production method according to any one of claims 1 to 5, characterized in that: and (2) carrying out uniform pulp rectification on the aramid fiber mixed dispersion liquid before net feeding to ensure that the fibers are dispersed by full turbulence.
7. The method of manufacturing according to claim 6, characterized in that: in the step (2), single-helix hole-array type, double-helix hole-array type hole rollers, sheet rollers or rod rollers are adopted for homogenate rectification; the concentration of the upper wire formed by the inclined wire is 0.01-0.08%.
8. The method for producing according to claim 7, characterized in that: the type of the aramid fiber in the step (1) is at least one of wholly aromatic polyamide fiber or heterocyclic aromatic polyamide fiber; the mechanical pretreatment is pre-pulping treatment by a disc grinder to obtain SR aramid fiber dispersion liquid with the pulping degree of 50-85 ℃;
adding a dispersing agent into the step (2), wherein the dispersing agent is one or more of N-methyl pyrrolidone, methoxy polyethylene glycol, polyethylene glycol dimethyl ether, polyethylene oxide, polyacrylamide and sodium polyacrylate, and the adding amount of the dispersing agent accounts for 0.01-2% of the mass of the aramid fiber;
the hot-press molding condition in the step (3) is that the temperature is 100-260 ℃, the pressure is 0.1-20 MPa, and the time is 0.1-24 h.
9. A high performance aramid membrane made by the method of any one of claims 1 to 8, wherein: a thickness of 25 μm or less, a porosity of 40 to 70%, a liquid absorption rate of 350% or more, a longitudinal tensile strength of 90MPa or more, a transverse tensile strength of 85MPa or more, and a puncture strength of 450g/mil or more.
10. The high-performance aramid separator of claim 9 is applied to a lithium ion battery.
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CN116377762A (en) * 2023-03-31 2023-07-04 陕西科技大学 Aramid fiber battery diaphragm paper with good electrolyte wettability and preparation method and application thereof
CN116544616A (en) * 2023-07-06 2023-08-04 烟台泰和新材高分子新材料研究院有限公司 Slurry of in-situ composite aromatic polyamide and preparation method and application thereof
CN116544616B (en) * 2023-07-06 2023-09-05 烟台泰和新材高分子新材料研究院有限公司 Slurry of in-situ composite aromatic polyamide and preparation method and application thereof

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