CN115207559B - 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 PDFInfo
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- 229920006231 aramid fiber Polymers 0.000 title claims abstract description 152
- 238000002360 preparation method Methods 0.000 title claims abstract description 41
- 239000004760 aramid Substances 0.000 claims abstract description 138
- 229920003235 aromatic polyamide Polymers 0.000 claims abstract description 127
- 239000000835 fiber Substances 0.000 claims abstract description 63
- 239000002994 raw material Substances 0.000 claims abstract description 29
- 239000007788 liquid Substances 0.000 claims abstract description 24
- 239000000463 material Substances 0.000 claims abstract description 20
- 238000007731 hot pressing Methods 0.000 claims abstract description 19
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims abstract description 18
- 229910001416 lithium ion Inorganic materials 0.000 claims abstract description 18
- 239000006185 dispersion Substances 0.000 claims abstract description 15
- 238000004519 manufacturing process Methods 0.000 claims abstract description 15
- 238000010521 absorption reaction Methods 0.000 claims abstract description 13
- 239000000758 substrate Substances 0.000 claims abstract description 12
- 230000001105 regulatory effect Effects 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims description 33
- 239000002270 dispersing agent Substances 0.000 claims description 8
- 239000002202 Polyethylene glycol Substances 0.000 claims description 7
- 229920001223 polyethylene glycol Polymers 0.000 claims description 7
- 238000010009 beating Methods 0.000 claims description 5
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 claims description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 3
- 125000000956 methoxy group Chemical group [H]C([H])([H])O* 0.000 claims description 3
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 2
- 125000006615 aromatic heterocyclic group Chemical group 0.000 claims description 2
- 238000009996 mechanical pre-treatment Methods 0.000 claims description 2
- 238000000465 moulding Methods 0.000 claims description 2
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 claims description 2
- 229920002401 polyacrylamide Polymers 0.000 claims description 2
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 claims description 2
- 238000007781 pre-processing Methods 0.000 claims 1
- 239000011148 porous material Substances 0.000 abstract description 10
- 239000002002 slurry Substances 0.000 description 18
- 229920000642 polymer Polymers 0.000 description 16
- 238000012360 testing method Methods 0.000 description 15
- 230000000694 effects Effects 0.000 description 13
- 238000002156 mixing Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 238000001035 drying Methods 0.000 description 10
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- 238000004537 pulping Methods 0.000 description 10
- 239000000243 solution Substances 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 8
- 238000005406 washing Methods 0.000 description 8
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 description 7
- FDQSRULYDNDXQB-UHFFFAOYSA-N benzene-1,3-dicarbonyl chloride Chemical compound ClC(=O)C1=CC=CC(C(Cl)=O)=C1 FDQSRULYDNDXQB-UHFFFAOYSA-N 0.000 description 7
- 239000012528 membrane Substances 0.000 description 7
- 229920000098 polyolefin Polymers 0.000 description 7
- WZCQRUWWHSTZEM-UHFFFAOYSA-N 1,3-phenylenediamine Chemical compound NC1=CC=CC(N)=C1 WZCQRUWWHSTZEM-UHFFFAOYSA-N 0.000 description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 230000001112 coagulating effect Effects 0.000 description 6
- 238000011161 development Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- 229910052744 lithium Inorganic materials 0.000 description 6
- 229940018564 m-phenylenediamine Drugs 0.000 description 6
- 230000007935 neutral effect Effects 0.000 description 6
- 238000009987 spinning Methods 0.000 description 6
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 5
- 238000005345 coagulation Methods 0.000 description 5
- 230000015271 coagulation Effects 0.000 description 5
- 239000003792 electrolyte Substances 0.000 description 5
- 239000003607 modifier Substances 0.000 description 5
- 238000005096 rolling process Methods 0.000 description 5
- 238000010008 shearing Methods 0.000 description 5
- 238000007711 solidification Methods 0.000 description 5
- 230000008023 solidification Effects 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 238000010041 electrostatic spinning Methods 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 239000011550 stock solution Substances 0.000 description 4
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 238000009998 heat setting Methods 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000006386 neutralization reaction Methods 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 229920002959 polymer blend Polymers 0.000 description 3
- 238000004321 preservation Methods 0.000 description 3
- 238000001878 scanning electron micrograph Methods 0.000 description 3
- 238000002791 soaking Methods 0.000 description 3
- 238000005303 weighing Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229920002593 Polyethylene Glycol 800 Polymers 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 2
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 2
- 239000000292 calcium oxide Substances 0.000 description 2
- 210000004027 cell Anatomy 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- 210000001787 dendrite Anatomy 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000011534 incubation Methods 0.000 description 2
- 230000037427 ion transport Effects 0.000 description 2
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 229940085675 polyethylene glycol 800 Drugs 0.000 description 2
- 230000010349 pulsation Effects 0.000 description 2
- 238000004513 sizing Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 238000001132 ultrasonic dispersion Methods 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910001622 calcium bromide Inorganic materials 0.000 description 1
- WGEFECGEFUFIQW-UHFFFAOYSA-L calcium dibromide Chemical compound [Ca+2].[Br-].[Br-] WGEFECGEFUFIQW-UHFFFAOYSA-L 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000010277 constant-current charging Methods 0.000 description 1
- 239000006184 cosolvent Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000005189 flocculation Methods 0.000 description 1
- 230000016615 flocculation Effects 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 230000009477 glass transition Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 238000005213 imbibition Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- -1 lithium hexafluorophosphate Chemical compound 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 238000005191 phase separation Methods 0.000 description 1
- 238000006068 polycondensation reaction Methods 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000002145 thermally induced phase separation Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- 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
Abstract
The invention discloses a high-performance aramid fiber diaphragm and a preparation method and application thereof, and the high-performance aramid fiber diaphragm comprises the following steps: (1) pretreatment of aramid fiber: taking differential aramid chopped fibers and differential aramid fibrid as raw materials, and mechanically pre-treating the raw materials to prepare an aramid fiber mixed dispersion liquid; and (2) manufacturing an aramid fiber diaphragm: regulating the concentration of the aramid fiber dispersion liquid, and then carrying out wet papermaking through an inclined wire shaper to obtain an aramid fiber diaphragm substrate; (3) hot pressing: and directly hot-pressing the prepared aramid fiber diaphragm base material to form, and finally preparing the high-performance aramid fiber diaphragm. The high-performance aramid fiber diaphragm has simple and convenient production process, excellent mechanical performance and high temperature resistance, adjustable pore structure and liquid absorption rate of the aramid fiber diaphragm, convenient matching of actual working scene requirements of the energy battery diaphragm and industrial expansion production, and can be widely used as a high-performance lithium ion battery diaphragm.
Description
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, so that the direct contact of anode and cathode materials can be effectively avoided, and the high-low temperature performance, the cycle stability and the like of the battery are obviously influenced. Therefore, the research and exploration of the novel high-performance diaphragm have important significance for developing high-performance and high-safety lithium ion batteries.
Currently, the preparation process of the battery separator is mainly divided into a dry method (melt stretching), a wet method (thermally induced phase separation, non-solvent induced phase separation), an electrostatic spinning method and the like. Wherein the polyolefin diaphragm is mainly dry method and wet method, and the meta-position aramid fiber and polyimide high molecular polymer diaphragm is mainly electrostatic spinning method. For example, the preparation methods of polyolefin separators are disclosed in Chinese patent 202080056546.2, 201880071194.0, 202010596751.X, etc., but when the working temperature exceeds 130 ℃, the shrinkage and mechanical property loss of the separator are serious, which will seriously affect the safe use of the battery. Also, commercial polyolefin separators (PP, PE) suffer from poor wettability due to poor thermal stability, relatively single functionality, resulting in rapid capacity fade at high rates. In the cyclic use, the electrode material (negative electrode lithium metal) forms lithium dendrite in a large amount due to nonuniform deposition of lithium ions, and the lithium dendrite directly pierces through a diaphragm along with the continuous growth of the battery in the cyclic use, so that the battery capacity is reduced, internal short circuit is caused for a long time, the service life of the battery is greatly shortened, and the safety problem is caused. To improve polyolefin separator properties, many researchers have explored these problems and have proposed solutions such as surface-modified inorganic nanoparticles (e.g., al 2 O 3 、SiO 2 Methods of surface grafting, and surface polymer coating in order to achieve improved heat resistance of the separator and wetting of the liquid electrolyteAnd the cycle stability and the multiplying power performance are improved. For example, the nano ceramic material coating is manufactured on the surface of the polyolefin microporous film in China patent 201110379586.3, so that the high-temperature thermal stability of the lithium ion battery is improved, the safety and the reliability of the lithium ion battery are improved, and the manufacturing difficulty of the diaphragm is obviously increased. On the other hand, the polyolefin material is generally a nonpolar material, for example, the contact angle of the surface of the PP film is close to 90 degrees, the hydrophobicity is strong, the water absorption after being coated and modified by an inorganic coating is improved, the contact angle of electrolyte can be reduced to about 65 degrees to a certain extent, but the energy consumption of a drying link in the production and assembly process of the lithium ion battery is obviously increased, and the cost is increased (Li Wenjun and the like, and the development strategy of the lithium battery with high energy density, 2020,9, 2:448-478). 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 60-80% of porosity is prepared, on one hand, the ultrasonic dispersion effect is limited, the industrialization difficulty is high, and on the other hand, the mechanical strength and the puncture resistance strength are directly reduced due to the fact that the porosity is too high, and the strength requirement of the diaphragm cannot be met. In addition, the nonwoven fabric method has been attracting more and more attention in recent years, and although the preparation process is simple, the porosity is very high, the pore size distribution is very uniform, and the micropores show a three-dimensional structure, the requirements of the lithium ion battery on the pore size and the thickness of the separator cannot be met at the same time.
So far, there are few methods for preparing high-performance aramid fiber diaphragm-based materials suitable for practical application by adopting a wet papermaking method. The lithium ion battery separator requires that the fiber diameter be in submicron or several microns, otherwise, the requirements of the pore diameter and the thickness of the separator are difficult to meet at the same time. The fiber diameter of the aramid commercialized at present is generally between tens of micrometers and tens of micrometers, and the requirements of producing the aramid diaphragm are difficult to meet. Chinese patent CN 104577011A discloses a battery separator reinforced material, which mainly comprises the steps of pulping and proportioning, forming by paper making, drying, hot rolling at high temperature, and the like. Because of the forming stage of papermaking, the cylinder mould is adopted for forming, so that the mechanical property of the material is reduced. In addition, the technology adopts aramid fiber with fineness of 1.2-3.2 dtex and density of 1.45g/cm 3 Calculation ofThe diameter of the used fiber is between 10.27 and 16.76 mu m, the thickness of 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 in national standard GBT 36363-2018 polyolefin diaphragm for lithium ion batteries is 16 mu m and 25 mu m. In addition, the fiber in the diaphragm can be more densely combined by high-temperature hot pressing, especially hot pressing at a temperature of more than 280 ℃ and a value higher than the glass transition temperature of meta-aramid, so that the porosity is influenced, and the service performance of the battery can be further influenced.
Along with the development of increasingly diversified, complicated, flexible and light-weight electronic products, the requirements on the lightening and thinning of battery diaphragms are increasingly high. In general, the thickness of a separator for a battery is as small as possible, and the thickness of the separator is reduced as much as possible. Low thickness separators are a trend in the development of current battery separator materials. The separator occupies a small volume in the battery structure, but the mechanical properties of the separator are affected by the excessive thinness, and the separator is easily punctured or torn, so that the short circuit between electrodes is caused, thereby reducing the overall safety performance of the battery (Venugopal G, moore J, howard J, et al, characial of microporous separators for lithium-ion batteries [ J ]. Journal of Power Sources,1999,77 (1): 34-41.). Thus, the preparation of thin and mechanically high performance separator materials is a current technical difficulty in the preparation of high performance separators. It is known that development of a high-performance separator manufacturing technology is urgently required to promote development of the technical field of battery separators.
Aiming at the problems in the development of lithium battery diaphragm technology, the uniform and efficient preparation of high-performance aramid diaphragm is the bottleneck of the prior art under the premise of ensuring proper porosity and high liquid absorption. The technical scheme develops a novel diaphragm in the lithium ion battery diaphragm, and improves the electrochemical performance and safety of the lithium ion battery by assistance.
Disclosure of Invention
In order to overcome the defects and shortcomings in the prior art, the primary purpose of the invention is to provide a high-performance aramid separator for improving the electrochemical performance and the safety of a lithium ion battery. The diaphragm has excellent mechanical property and high temperature resistance, and the aperture structure and the liquid absorption rate of the aramid diaphragm can be regulated and controlled, so that the diaphragm is convenient to match with the actual working scene requirement of the energy battery diaphragm and the industrial expansion production.
The invention also aims to provide a preparation method of the high-performance aramid fiber diaphragm, and the production process is simple and convenient.
It is still another object of the present invention to provide the use of the high performance aramid separator described above in lithium ion batteries.
The aim of the invention is achieved by the following technical scheme:
the preparation method of the high-performance aramid fiber diaphragm comprises the following steps:
(1) Pretreatment of aramid fiber: taking differential aramid chopped fibers and differential aramid fibrid as raw materials, mixing the raw materials, and then mechanically pre-treating (or respectively mechanically pre-treating 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 an aramid fiber diaphragm: regulating the concentration of the aramid fiber mixed dispersion liquid, and then carrying out wet papermaking through an inclined wire shaper to obtain an aramid fiber diaphragm substrate;
(3) And (3) hot pressing: and directly hot-pressing the prepared aramid fiber diaphragm base material to form, and finally preparing the high-performance aramid fiber diaphragm.
Preferably, the differential aramid chopped fiber in the step (1) is an aramid fiber with the diameter of 2-10 mu m and the length of 3-20 mm; the aramid fibrid is an aramid fiber with the width of 2-20 mu m, the length of 0.5-5 mm and the average thickness of less than or equal to 200 nm.
Preferably, the differential aramid chopped fiber in the step (1) is an aramid fiber with the diameter of 2-8 mu m and the length of 10-20 mm; the aramid fibrid has the width of 5-10 mu m, the length of 3-5 mm and the average thickness of less than or equal to 150nm.
Preferably, in step (2), the aramid fiber dispersion is subjected to a slurry homogenizing and rectifying process prior to the screen-feeding process, so that the fibers are subjected to a sufficiently turbulent dispersion.
Preferably, in the step (2), the homogenizing rectification adopts a single-helix hole array type, a double-helix hole array type hole roller, a sheet roller or a rod roller; the net-feeding concentration of the inclined net forming 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): 99-1; the concentration of the aramid fiber mixed dispersion liquid in the step (2) 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) (90-10); the concentration of the aramid fiber mixed dispersion liquid in the step (2) is 0.01-0.10%.
Preferably, 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 to obtain the SR aramid fiber dispersion liquid with the beating degree of 50-85 degrees through the pre-beating treatment of a disc grinder.
Preferably, in the step (2), a dispersing agent is further added, wherein the dispersing agent is one or more of N-methylpyrrolidone, methoxy polyethylene glycol, polyethylene glycol dimethyl ether, polyethylene oxide, polyacrylamide and sodium polyacrylate, and the adding amount is 0.01-2% of the mass of the aramid fiber.
Preferably, 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.
The high-performance aramid fiber diaphragm prepared by the method has the thickness of less than 25 mu m, the porosity of 40-70%, the liquid absorption rate of more than 350%, the longitudinal tensile strength of more than 90MPa, the transverse tensile strength of more than 85MPa and the puncture strength of more than 450 g/mil; preferably, the thickness is 10-25 μm, the porosity is 40-70%, the liquid absorption rate is above 460%, the longitudinal tensile strength is above 135MPa, the transverse tensile strength is above 125MPa, and the puncture strength is above 620 g/mil. More preferably, it has a thickness of 14-22 μm, a porosity of 55-65%, a liquid absorption of 460-750%, a longitudinal tensile strength of 135-200MPa, a transverse tensile strength of 125-200MPa, and a puncture strength of 620-750g/mil.
The preparation process of the aramid fiber raw material comprises the following steps: the m-phenylenediamine and isophthaloyl dichloride (molar ratio 100:90-120) are subjected to one-step low-temperature (0-20 ℃) polycondensation reaction to prepare the catalyst. Specifically, a cosolvent and m-phenylenediamine are dissolved in N, N-dimethylacetamide under the conditions of low temperature (0-20 ℃) and nitrogen protection, then m-phthaloyl chloride is added for a plurality of times, the temperature of the m-phthaloyl chloride gradually rises along with the reaction, and an alkaline agent is added for neutralization after heat preservation (50-90 ℃) treatment, so that a neutral aramid polymer solution is prepared; then adding a proper amount of modifier (10-40%) into the neutral aramid polymer, fully mixing and dispersing at a certain temperature (50-150 ℃), and filtering and defoaming to obtain the polymer blend.
Preparation of superfine aramid fiber: and (3) conveying the obtained polymer blend to a spinneret plate, and sequentially carrying out spinning, solidification, drafting, washing, drying, heat setting and rolling to finally prepare the superfine aramid fiber.
Preparation of aramid fibrid: and (3) conveying the obtained polymer blend to a precipitation device, performing non-solvent diffusion pre-solidification, and performing multistage washing after two-stage high-shear action to finally obtain the tow-shaped fibrid. The differential superfine aramid fiber and fibrid can be obtained by adjusting main technological parameters such as the mixture ratio of the aramid fiber blend, the solidification condition, the draft ratio, the shearing process and the like.
The size of the aramid chopped fiber, the aramid fibrid or the aramid pulp prepared by the conventional method is tens of micrometers or more, the thickness of the commercial battery diaphragm is a porous film smaller than 25 micrometers, the diameter/thickness and strength of the fiber prepared by the conventional method can not meet the requirements, the battery diaphragm with moderate thickness and porosity is difficult to produce, and researchers find out the fiber with the size of a few micrometers or less. The invention prepares superfine aramid fiber and fibrid based on polymer modification technology, the size is several micrometers or even smaller, adopts hole roller and the like to optimize high-strength pulsation turbulence field, promotes superfine fiber raw material to generate effective turbulence and disperse uniformly, prepares light and thin high-strength aramid fiber diaphragm by effectively combining ultra-low concentration forming technology, realizes organic unification of porosity, thickness and mechanical property of the aramid fiber diaphragm cooperatively, and ensures the use safety of high-performance battery.
Compared with the prior art, the invention has the following advantages and effects:
according to the high-performance aramid fiber diaphragm, the surface modification is carried out on the aramid fiber, so that the distribution and interface combination effect of the aramid fiber in an aramid fiber diaphragm base material are improved, the surface pore structure of the aramid fiber diaphragm is optimized, the combination effect among the aramid fiber 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, and the excellent mechanical property, the excellent temperature resistance and the like of the aramid fiber are used to increase the interface bonding effect of the fiber in the diaphragm, so that the high-strength aramid diaphragm is prepared, and the manufacturing cost can be saved.
In addition, the invention 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 diaphragm. The porosity is the ratio of the micropore volume to the whole volume of the diaphragm, and reflects the number of micropores of the diaphragm. Furthermore, too high a porosity can directly lead to a decrease in mechanical strength and puncture resistance, failing to meet the strength requirements of the membrane; too low a porosity increases the internal resistance of ion transport, resulting in a decrease in 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 reduces the conduction resistance of lithium ions between two electrodes. The porosity of the aramid fiber diaphragm prepared by the method is between 43.9% and 63.7%, and the aramid fiber diaphragm can be optimally regulated and controlled according to practical application scenes, so that the capacity retention rate of the battery is improved while the ion conduction capacity of the battery is improved. And the differential aramid fiber is easy to form a microporous structure, so that capillary effect is generated, and effective absorption of electrolyte is promoted. Because the superfine aramid chopped fibers and the differential aramid fibrid are fully mixed in the mechanical treatment process, finer aramid fibers are fully interwoven to form a large number of pore structures smaller than 1 micron, the fiber interface bonding is improved, the good puncture strength is maintained to a certain extent, 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.
Moreover, the invention uses the treated aramid fiber differential fiber as a raw material for the first time, adopts hole rollers and the like to optimize a high-strength pulsation turbulence field, so that longer aramid fiber generates full and effective turbulence in a sizing flow channel, and the fiber in the sizing flow is uniformly dispersed. In addition, the pore roller and the like can form an upstream and downstream rectifying area for slurry flow to form strong turbulence, the depolymerization effect on the slurry flow is stronger, the flocculation of slender aramid fibers is effectively avoided, the ultra-low concentration inclined wire forming is cooperated to prepare the aramid fiber diaphragm with high porosity and liquid absorption rate, and the mechanical strength, heat resistance, wettability and other performances of the diaphragm are cooperatively improved. According to the invention, the influence of different film forming/forming methods of the aramid fiber on the implementation effect of the diaphragm is further optimized through experiments in the examples and the comparative examples, and technical implementation effect data show that the effect is completely better than the effect of the prior art.
Drawings
FIG. 1 is a flow chart of the preparation of a high performance aramid separator.
Fig. 2 is a cross-sectional SEM image of the ultra-fine aramid fiber.
Fig. 3 is an SEM image of the aramid fibrid surface.
Fig. 4 is a SEM image of the surface of a high performance aramid separator.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but embodiments of the present invention are not limited thereto.
The starting materials in the preparation method of the present invention may be obtained commercially or according to the prior art method, and the aramid fiber used in the examples of the present invention is meta-aramid fiber, but is not limited thereto.
Example 1
The preparation method of the high-performance aramid fiber diaphragm comprises the following steps of:
(1) Preparation of an aramid polymer: m-phenylenediamine is dissolved in N, N-dimethylacetamide at a low temperature of 5 ℃ under the condition of nitrogen protection, calcium bromide is added, and then m-phthaloyl chloride is added for 3 times, wherein the molar ratio of the m-phenylenediamine to the m-phthaloyl chloride is controlled to be 100:103. the temperature was gradually increased to 80℃as the reaction proceeded, and the incubation time was 3h. 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 absolute dry mass ratio of the modifier to the aramid polymer is 30:70, and the mixing temperature is 70 ℃. Filtering and defoaming after fully mixing and dispersing to obtain spinning solution;
(3) Preparation of superfine aramid fiber: and (3) conveying the spinning solution obtained in the step (2) to a spinneret plate, and sequentially carrying out spinning, solidification, drafting, washing, drying, heat setting and winding to finally obtain the superfine aramid fiber. The specific parameters are as follows, spinning process: the aperture range of the spinneret plate is 0.05mm, and the aperture number is 8000; the distance between the spinneret plate and the coagulating bath is 15cm; and (3) solidifying, washing and drafting: the primary coagulating bath comprises the following components in percentage by mass: n, N-dimethylacetamide: glycerol: water, etc. =70:15:15; the coagulation bath temperature was 70℃and the draft ratio was 1.6 times. The secondary coagulating bath comprises the following components in percentage by mass: n, N-dimethylacetamide: water=60:40, coagulation bath temperature 70 ℃, second stage coagulation bath draft ratio 2.5 times. The temperature of the first-stage water washing is 40 ℃, and the draft ratio is 1.5 times; the water temperature of the second-stage water washing is 85 ℃. The drying temperature was 110 ℃. The hot drawing temperature is 285 ℃, and the drawing multiplying power is 2.9 times. The heat setting temperature is 295 ℃.
The obtained aramid fiber is cut into the length of 6-20 mm according to the requirements of the embodiment, and the diameter of the superfine aramid fiber prepared by the embodiment is 3.0 μm through the test of a scanning electron microscope, and an SEM (scanning electron microscope) graph of the cross section is shown in figure 2. The superfine aramid fibers with different diameters can be obtained by adjusting the main technological parameters such as the proportion of the modifier to the aramid polymer, the distance between the spinneret plate and the coagulating bath, the coagulating condition, the drawing multiplying power and the like.
Example 2
The preparation method of the high-performance aramid fiber diaphragm comprises the following steps of:
(1) Preparation of an aramid polymer: m-phenylenediamine is dissolved in N, N-dimethylacetamide at a low temperature of 5 ℃ under the condition of nitrogen protection, lithium chloride is added, and then m-phthaloyl chloride is added for 3 times, wherein the molar ratio of the m-phenylenediamine to the m-phthaloyl chloride is controlled to be 100:103. the temperature was gradually increased to 80℃as the reaction proceeded, and the incubation time was 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 absolute dry mass ratio of the modifier to the aramid polymer is 40:60, and the mixing temperature is 70 ℃. Filtering after fully mixing and dispersing, removing bubbles to obtain a precipitation stock solution;
(3) Preparation of 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 water washing treatment to obtain aramid fiber fibrids. The concrete process comprises the following components in mass ratio in the first-stage high-speed shearing treatment process: n, N-dimethylacetamide: water=50:50, coagulation bath temperature 70 ℃, shear rate 7000rpm; in the second-stage high-speed shearing treatment process, the coagulating bath comprises the following components in parts by mass: n, N-dimethylacetamide: water=30:70, coagulation bath temperature 50 ℃, shear rate 8000rpm. And obtaining aramid fibrid through multistage washing.
The aramid fibrids prepared in this example have a width of about 15 μm, a length of about 4mm, a thickness of less than 200nm and an original freeness of 49 ° SR. The aramid fibrids with different size parameters can be obtained by adjusting the main technological parameters such as the proportion of the modifier to the aramid polymer, the solid content of the feed blend, the solidification condition, the shearing rate and the like.
Example 3
A preparation method of the high-performance aramid fiber diaphragm comprises the following steps:
(1) Preparing an aramid fiber raw material: the differential aramid chopped fiber and the differential aramid 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 10.1 mu m; the aramid fibrids are in the shape of a sheet, the average width is 20 mu m, the average length is 0.6mm, and the average thickness is 200nm; the absolute dry mass ratio of the aramid fibrid to the aramid chopped fiber is 60:40. Pre-pulping by a disc mill after uniformly mixing to obtain differential aramid fiber slurry with the pulping degree of 50 DEG SR;
(2) Preparation of an aramid membrane substrate: the differential aramid fiber slurry is taken as a raw material, methoxy polyethylene glycol is added as a dispersing agent, and the addition amount accounts for 2% of the total mass of the aramid fiber. And (3) adopting a pore plate to homogenize slurry flow before surfing the net, combining ultra-low concentration forming wet papermaking, wherein the surfing concentration of the ultra-low concentration forming is 0.08%, and drying and rolling to obtain the aramid fiber diaphragm substrate.
(3) Preparation of an aramid fiber diaphragm: and selecting a certain amount of aramid fiber diaphragm base material, and then carrying out hot pressing treatment at the temperature of 260 ℃ under the pressure of 1MPa, wherein the high-performance aramid fiber diaphragm can be obtained after 10 minutes of hot pressing.
The performance index of the aramid separator was measured and the test results are shown in table 1.
Example 4
A preparation method of the high-performance aramid fiber diaphragm comprises the following steps:
(1) Preparing an aramid fiber raw material: the differential aramid chopped fiber and the differential aramid fibrid are selected 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 fibrids are in the shape of a sheet, the average width is 15 mu m, the average length is 0.8mm, and the average thickness is 160nm; the absolute dry mass ratio of the aramid fibrid to the aramid chopped fiber is 50:50. Pre-pulping by a disc mill after uniformly mixing to obtain differential aramid fiber slurry with the pulping degree of 67 DEG SR;
(2) Preparation of an aramid membrane substrate: the differential aramid fiber slurry is taken as a raw material, N-methyl pyrrolidone is added as a dispersing agent, and the addition amount accounts for 0.01 percent of the total mass of the aramid fiber. And (3) homogenizing the slurry flow by adopting a double-spiral line hole-arranging type hole roller before surfing the net, combining with ultra-low concentration forming wet papermaking, wherein the concentration of surfing the net by ultra-low concentration forming is 0.05%, and drying and rolling to obtain the aramid fiber diaphragm substrate.
(3) Preparation of an aramid fiber diaphragm: and selecting a certain amount of aramid fiber diaphragm base material, and then carrying out hot pressing treatment at the temperature of 240 ℃ under the pressure of 2MPa, wherein the high-performance aramid fiber diaphragm can be obtained after hot pressing for 5 min.
The performance index of the aramid separator was measured and the test results are shown in table 1.
Example 5
A preparation method of the high-performance aramid fiber diaphragm comprises the following steps:
(1) Preparing an aramid fiber raw material: the differential aramid chopped fiber and the differential aramid 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 fibrids are in the shape of a sheet, the average width is 10 mu m, the average length is 2.4mm, and the average thickness is 130nm; the absolute dry mass ratio of the aramid fibrid to the aramid chopped fiber is 45:55. Pre-pulping by a disc mill after uniformly mixing to obtain differential aramid fiber slurry with a beating degree of 72 DEG SR;
(2) Preparation of an aramid membrane substrate: the differential aramid fiber slurry is taken as a raw material, polyethylene glycol dimethyl ether is added as a dispersing agent, and the addition amount accounts for 0.6 percent of the total mass of the aramid fiber. And (3) adopting a sheet roller to homogenize the pulp flow before surfing the net, combining ultra-low concentration forming wet papermaking, wherein the surfing concentration of the ultra-low concentration forming is 0.08%, and drying and rolling to obtain the aramid fiber diaphragm substrate.
(3) Preparation of an aramid fiber diaphragm: and selecting a certain amount of aramid fiber diaphragm base material, and then carrying out hot pressing treatment at the temperature of 150 ℃ under the pressure of 6MPa, wherein the hot pressing is carried out for 20 minutes to obtain the high-performance aramid fiber diaphragm.
The performance index of the aramid separator was measured and the test results are shown in table 1.
Example 6
A preparation method of the high-performance aramid fiber diaphragm comprises the following steps:
(1) Preparing an aramid fiber raw material: the differential aramid chopped fiber and the differential aramid fibrid are selected 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 fibrids are in the shape of a sheet, the average width is 5 mu m, the average length is 4.1mm, and the average thickness is 100nm; the absolute dry mass ratio of the aramid fibrid to the aramid chopped fiber is 30:70. Pre-pulping by a disc mill after uniformly mixing to obtain differential aramid fiber slurry with the pulping degree of 82 DEG SR;
(2) Preparation of an aramid membrane substrate: the differential aramid fiber slurry is taken as a raw material, polyethylene glycol dimethyl ether is added as a dispersing agent, and the addition amount accounts for 0.8 percent of the total mass of the aramid fiber. And before surfing the net, adopting a single spiral line hole-arrangement type uniform slurry flow, combining with ultra-low concentration forming wet papermaking, wherein the concentration of surfing the net by ultra-low concentration forming is 0.01%, and drying and rolling to obtain the aramid fiber diaphragm substrate.
(3) Preparation of an aramid fiber diaphragm: and selecting a certain amount of aramid fiber diaphragm base material, and then carrying out hot pressing treatment under the conditions of 10MPa and 220 ℃ for 5min to obtain the high-performance aramid fiber diaphragm.
The performance index of the aramid separator was measured and the test results are shown in table 1. The surface pore structure of the prepared aramid fiber diaphragm is shown in figure 3.
Example 7
This embodiment differs from embodiment 6 in that: the average width of the aramid fibrids in the step (1) is 10 mu m, the average length is 2.4mm, and the average thickness is 130nm.
The performance index of the aramid separator was measured and the test results are shown in table 1.
Example 8
This embodiment differs from embodiment 6 in that: the average length of the aramid chopped fibers in the step (1) is 10mm, and the average diameter of the aramid chopped fibers is 7.4 mu m.
The performance index of the aramid separator was measured and the test results are shown in table 1.
Example 9
This embodiment differs from embodiment 6 in that: in the step (1), the treatment process of adopting a single spiral line hole arrangement type slurry flow leveling before surfing the net is omitted, and other conditions are unchanged.
The performance index of the aramid separator was measured and the test results are shown in table 1. The prepared aramid fiber diaphragm has poorer uniformity and obviously reduced mechanical property compared with the aramid fiber diaphragm prepared in the embodiment 6, which is probably caused by that the aramid fiber is not subjected to full turbulence dispersion, so that part of the fibers are agglomerated, and the mechanical property and the electrochemical property of the diaphragm are influenced.
Comparative example 1
An electrostatic spinning aramid fiber diaphragm, its preparation method is as follows:
weighing 10% by mass of aramid polymer, and removing bubbles in vacuum to obtain a uniform solution; transferring the solution into a 10ml syringe (needle specification: 18G), fixing the syringe on a laboratory injection pump, clamping an 18kV high-voltage power supply on the needle, adjusting the height and position of the needle, adjusting the advancing speed of the syringe to be 1ml/h and the receiving distance to be 15cm so that the fiber can be sprayed to a target position, coating an aluminum foil on a high-speed roller as a receiving device to collect the fiber, adjusting the rotating speed of the roller to be 250r/min, and adjusting the spinning temperature to be 25-30 ℃ and the relative humidity to be 40-60%. And selecting a certain amount of aramid fiber diaphragm base material, then carrying out hot pressing treatment under the conditions of 2MPa and 150 ℃ and hot pressing for 10min to obtain the electrostatic spinning aramid fiber diaphragm.
Comparative example 2
The present comparative example differs from example 5 in that: the papermaking mode in the step (2) is cylinder mould forming.
The performance index of the aramid separator was measured and the test results are shown in table 1. The comparison with the data of example 5 shows that the strength of the same fiber raw material is obviously reduced after the fiber raw material is subjected to cylinder mould paper making, and the longitudinal and transverse strength difference is obviously increased.
Comparative example 3
An aramid fiber diaphragm, its preparation method is as follows:
(1) Preparing an aramid fiber raw material: the method selects the conventional aramid chopped and precipitated fiber and takes the chopped and precipitated fiber 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 film shape, the average width is 100 mu m, the average length is 0.8mm, and the average thickness is more than 500nm; the absolute dry mass ratio of the aramid fibrid to the aramid chopped fiber is 50:50. Pre-pulping by a disc mill after uniformly mixing to obtain differential aramid fiber slurry with a pulping degree of 30 DEG SR;
(2) Preparation of an aramid membrane substrate: the aramid fiber slurry is used as a raw material, a single spiral line arranged hole roller is adopted to homogenize slurry flow before surfing, ultra-low concentration forming wet papermaking is combined, the surfing concentration of the ultra-low concentration forming is 0.05%, and the aramid fiber diaphragm base material is obtained through drying and winding.
(3) Preparation of an aramid fiber diaphragm: and selecting a certain amount of aramid fiber diaphragm base material, and then carrying out hot pressing treatment at the temperature of 240 ℃ under the pressure of 2MPa, wherein the high-performance aramid fiber diaphragm can be obtained after 20 minutes of hot pressing.
The performance index of the aramid separator was measured and the test results are shown in table 1.
Comparative example 4
The present comparative example differs from comparative example 3 in that: in the step (2), the cylinder mould forming wet papermaking is adopted to replace the ultra-low concentration forming wet papermaking in the papermaking condition.
Comparative example 5
The present comparative example differs from comparative example 4 in that:
the average width of the aramid fibrids in the step (1) is 15 mu m, the average length is 0.8mm, and the average thickness is 160nm.
The performance index of the aramid separator was measured and the test results are shown 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 adopting a strip-shaped sample method according to the specification in GB/T29627.2-2013; moisture was measured according to GB/T29627.2-2013; heat shrinkage the separator was treated at 250 ℃ for 24 hours, and the percentage change in area of the separator after shrinkage (%) = (a) was recorded by photographing 0 -A)/A 0 X 100, A o Refers to the initial area of the separator and a is the final area of the separator after heat treatment. In the liquid absorption rate measurement method: and (3) putting a circular diaphragm with the diameter of 18mm into lithium hexafluorophosphate electrolyte for soaking for 4 hours, and weighing the soaked mass. Liquid absorption = [ (M) 1 -M 0 )/M 0 ]X 100; wherein M is 0 And M 1 The mass of the diaphragm before and after the diaphragm is soaked in electrolyte is g; puncture resistance is measured with reference to ASTM F1306-90; porosity was measured using n-butanol imbibition: soaking a circular diaphragm with the diameter of 18mm in n-butanol solution for 4 hours, 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 membrane before and after soaking n-butanol is g; ρ is the density of n-butanol, 0.81g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the V is the volume of the diaphragm, in cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The ion conductivity is calculated by measuring the bulk impedance of the analog cell, where the ion conductivity=l/(r×a) formula: l is the thickness of the separator; a is the effective contact area of the diaphragm, and R is the body resistance (omega) of the diaphragm. And (3) battery assembly: in a glove box filled with argon, assembling the positive electrode shell, the stainless steel sheet, the diaphragm, the stainless steel sheet and the negative electrode shell into a button cell in sequence, and standing for 12 hours after packaging. Cycle performance of batteryThe test is carried out 100 times of constant current charging and discharging at the current density of 0.5C, and the voltage ranges are as follows: the capacity retention (%) was calculated by dividing the capacity after 100 test cycles by the capacity of the first test, 3.0V to 4.2V.
Table 1 mechanical properties test data for high performance aramid diaphragms prepared in examples
As can be seen from Table 1, the high-performance aramid diaphragm provided by the invention has various indexes superior to those of the conventional diaphragm material. Because the separator bears a larger pressure between the electrodes, as can be seen from Table 1, the thickness, strength and electrochemical performance indexes of the aramid paper prepared by the aramid fibers with conventional diameters are far higher than those of the aramid separator prepared by the superfine aramid fibers. The aramid fiber diaphragm prepared by the invention has excellent puncture resistance, and can effectively prevent battery short circuit caused by diaphragm puncture; on the other hand, increasing the puncture resistance of the separator helps to reduce the degree of deformation of the separator pores to promote uniform flow of li+ current. As can be seen from FIG. 2, the average diameter of the aramid fibers used in the present invention is about 3 μm, which can effectively increase the bonding effect between the aramid fibers during the forming process; as can be seen from FIG. 3, the aperture of the aramid fiber diaphragm prepared by the method is clearly visible, and the aperture is formed by interlacing aramid fibers, and the aperture size is smaller than 1 mu m. The aramid fiber diaphragm provided by the invention can effectively unify the thickness, the porosity and the mechanical properties of the battery diaphragm material. In conclusion, the high Jiang Maidong turbulent flow field is adopted, so that the superfine fiber raw material is promoted to be effectively turbulent and uniformly dispersed, the ultra-low concentration forming technology is effectively combined to prepare the light and thin high-strength aramid fiber diaphragm, 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 the high-performance battery is ensured.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (9)
1. The preparation method of the aramid fiber diaphragm is characterized by comprising the following steps of:
(1) Pretreatment of aramid fiber: taking differential aramid chopped fibers and differential aramid fibrid as raw materials, and mechanically preprocessing 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 an aramid fiber diaphragm: regulating the concentration of the aramid fiber mixed dispersion liquid, carrying out homogenizing rectification to ensure that the fibers are dispersed by full turbulence, and then carrying out wet papermaking by an inclined wire shaper to obtain an aramid diaphragm substrate; the net-feeding concentration of the inclined net forming is 0.01-0.08%;
(3) And (3) hot pressing: and directly hot-pressing the prepared aramid fiber diaphragm base material to form the aramid fiber diaphragm.
2. The method of manufacturing according to claim 1, characterized in that: the differential aramid chopped fiber in the step (1) is an aramid chopped fiber with the diameter of 2-10 mu m and the length of 3-20 mm; the aramid fibrid has the width of 2-20 mu m, the length of 0.5-5 mm and the average thickness of less than or equal to 200 nm.
3. The preparation method according to claim 2, characterized in that: 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 mu m, the length is 3-5 mm, and the average thickness is less than or equal to 150nm.
4. The method of manufacturing according to claim 1, characterized in that: the mass ratio of the aramid fibrid to the aramid chopped fiber in the step (1) is (1-99) (99-1); the concentration of the aramid fiber mixed dispersion liquid in the step (2) is 0.01-0.5%.
5. The method of manufacturing according to claim 4, wherein: the mass ratio of the aramid fibrid to the aramid chopped fiber in the step (1) is (10-90) (90-10); the concentration of the aramid fiber mixed dispersion liquid in the step (2) is 0.01-0.10%.
6. The method according to any one of claims 1 to 5, wherein: and (3) homogenizing rectification in the step (2) adopts a single spiral line hole-arranging type hole roller, a double spiral line hole-arranging type hole roller, a sheet roller or a rod roller.
7. The method of manufacturing according to claim 6, wherein: 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 to obtain an SR aramid fiber dispersion liquid with the beating degree of 50-85 degrees through the pre-beating treatment of a disc grinder;
the step (2) is also added with a dispersing agent, 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 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.
8. An aramid separator made by the method of any one of claims 1-7, characterized in that: the thickness is below 25 μm, the porosity is 40-70%, the liquid absorption rate is above 350%, the longitudinal tensile strength is above 90MPa, the transverse tensile strength is above 85MPa, and the puncture strength is above 450 g/mil.
9. The use of the aramid separator of claim 8 in a lithium ion battery.
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| CN116023115B (en) * | 2022-12-01 | 2024-01-05 | 武汉中科先进材料科技有限公司 | Silicon aerogel-nanofiber composite membrane and preparation method thereof |
| CN116200961A (en) * | 2023-03-31 | 2023-06-02 | 陕西科技大学 | High-temperature-resistant aramid battery diaphragm paper and preparation method and application thereof |
| 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 |
| 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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