CN114171849A - Core-shell structure composite diaphragm and preparation method thereof - Google Patents
Core-shell structure composite diaphragm and preparation method thereof Download PDFInfo
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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
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
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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
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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
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
- H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
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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
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/431—Inorganic material
- H01M50/434—Ceramics
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- 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
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- 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
A core-shell structure composite diaphragm and a preparation method thereof. The invention belongs to the field of lithium ion battery diaphragms. The invention aims to solve the technical problems of poor cycle and rate capability of a lithium battery, low capability of inhibiting the growth of lithium dendrite and poor thermal stability caused by insufficient binding force, large volume resistance and low compounding efficiency of the conventional composite diaphragm directly blending the ceramic filler and the polyvinylidene fluoride. The core-shell structure composite diaphragm is prepared from a ceramic filler and a polymer substrate, wherein the ceramic filler is uniformly dispersed in the polymer substrate, and the ceramic filler is of a core-shell structure consisting of a ceramic core and a polymer shell. According to the invention, the polymer is coated on the outer layer of the inorganic ceramic particles, the core-shell structure units which are uniformly coated are synthesized by self-assembly, and then the core-shell structure units are added into the polymer matrix to prepare the composite diaphragm with the core-shell structure, so that the diaphragm which has high mechanical strength, high wettability, good interface combination and can effectively inhibit lithium dendrites is realized.
Description
Technical Field
The invention belongs to the field of lithium ion battery diaphragms, and particularly relates to a core-shell structure composite diaphragm and a preparation method thereof.
Background
Energy is a permanent topic about human social development, and the key to realizing sustainable energy development is to research and develop novel energy to replace traditional energy based on petrochemical industry. Because of its higher mass/volume capacity, power density, longer cycle life and lower self-discharge efficiency, lithium ion batteries have become the focus of research in the energy field and have important applications in many fields, such as electric vehicles, consumer electronics, backup power supplies and wind and solar storage.
A lithium ion battery is a rechargeable battery that charges and discharges by lithium ions moving back and forth between a positive electrode and a negative electrode and stores energy. A layer of diaphragm made of polyethylene or polypropylene is generally arranged between anode and cathode materials of the existing commercial lithium ion battery, and the diaphragm is soaked in an alkyl organic carbonate solution containing lithium salt. The diaphragm has the function of providing a framework and a channel for lithium ions to move between the positive electrode and the negative electrode and simultaneously blocking the conduction of electrons between the positive electrode and the negative electrode. Commercial positive electrode materials mainly include transition metal oxides and phosphoric acid compounds (LiCoO)2,LiMn2O4,LiCoxMnyNi1-x-yO2,LiFePO4) The negative electrode material is mainly graphite. The diaphragm material is one of the key components of an electrochemical storage power supply, and an ideal lithium ion battery diaphragm has high liquid absorption rate, ionic conductivity, thermal stability, cycle life and low cost. Polyolefin separators widely used in the industry have not been able to satisfactorily meet the requirements of lithium batteries for high safety, high stability and high energy density, and have flammability and poor thermal stabilityThe separator is easily thermally shrunk during the operation of the battery to cause short-circuit failure, thereby severely limiting the safe application of the battery. In addition, the polyolefin separator has a poor liquid absorption rate, generally exhibits a solid-liquid separation state in an electrolyte, and forms an interface with an electrode having poor compatibility, thereby forming an unstable Solid Electrolyte Interface (SEI) to deteriorate the stability of a lithium negative electrode cycle. The SEI phase is easily broken under stress to expose a new lithium surface, which leads to continuous consumption and degradation of lithium metal, formation of uneven lithium deposition leading to dendrite growth, and finally piercing of the separator leading to potential safety hazards.
In order to improve the potential safety hazard of commercial separators, a great number of researchers improve the structure or material composition of the separator by adding ceramic particles, and develop a great number of high-performance lithium battery separator materials. However, the surfaces of commercial polyolefin separators prepared by dry and wet processes are difficult to functionalize, and coating of ceramic particles in commercial separators causes problems of pore blockage, reduction in liquid absorption properties, reduction in the ability to suppress lithium dendrites, and the like. Researchers have found that polyvinylidene fluoride (PVDF) as a binder applied to the surface of a commercial membrane can solve the above problems, and thus have been drawing attention in the field of membrane research. However, such composite membranes have their own limitations: the mechanical property is low, the functionalization does not realize molecular level, the technical problems of insufficient binding force, increased thickness and bulk resistance, random compounding, composite efficiency and the like exist between the ceramic and polymer interfaces, and the development of the diaphragm with excellent comprehensive performance is particularly important.
Disclosure of Invention
The invention provides a core-shell structure composite diaphragm and a preparation method thereof, aiming at solving the technical problems of poor cycle and rate capability of a lithium battery, low capability of inhibiting growth of lithium dendrite and poor thermal stability caused by insufficient binding force, large volume resistance and low compounding efficiency of the existing composite diaphragm directly blending ceramic filler and polyvinylidene fluoride.
The core-shell structure composite diaphragm is prepared from a ceramic filler and a polymer substrate, wherein the ceramic filler is of a core-shell structure and is uniformly dispersed in the polymer substrate, and the ceramic filler is composed of a ceramic core and a polymer shell.
Further limiting, the polymer substrate is one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trifluoroethylene, polyvinylidene fluoride-chlorotrifluoroethylene, polymethyl methacrylate, polyimide and polyacrylonitrile.
Further limiting, the mass fraction of the ceramic filler in the core-shell structure composite diaphragm is 5-15%.
Further, the ceramic core is one or more of alumina, silicon dioxide, zirconium dioxide, boron nitride, glass fiber and layered silicate minerals.
Further, the ceramic core has a particle size of 20nm to 200 nm.
Further limited, the polymer shell is one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate and polyimide.
Further, the mass ratio of the polymer shell to the ceramic core is (1.5-3): 1.
Further limiting, the thickness of the polymer shell layer is 4 nm-5 nm.
The preparation method of the core-shell structure composite diaphragm is carried out according to the following steps:
step 1: dispersing the ceramic core material in deionized water, magnetically stirring at normal temperature until the ceramic core material is uniformly dispersed, then adding a cross-linking agent, continuously magnetically stirring until the ceramic core material is uniformly dispersed, centrifuging, and drying to obtain modified ceramic powder;
step 2: dispersing the modified ceramic powder obtained in the step 1 into an organic solvent, adding a polymer shell material, stirring at normal temperature until the modified ceramic powder is uniformly dispersed, centrifuging, drying and ball-milling to obtain the core-shell structure ceramic filler;
and step 3: dissolving a polymer substrate material in acetone, magnetically stirring at 50-70 ℃ to obtain a transparent colloidal solution, then continuously magnetically stirring at room temperature for 0.5-1 h, cooling to room temperature, adding the core-shell structure ceramic filler obtained in the step (2), and magnetically stirring for 6-12 h to obtain a mixed solution;
and 4, step 4: and (4) coating the mixed solution obtained in the step (3) to obtain the core-shell structure composite diaphragm.
Further limiting, in the step 1, the mass ratio of the ceramic core material to the deionized water is 1: (20 to 50).
Further limiting, the mass ratio of the ceramic core material to the cross-linking agent in the step 1 is (2-20): 1.
Further limiting, in the step 1, the cross-linking agent is one of polyacrylonitrile, cellulose, citric acid, KH550, KH560 and KH 570.
Further limiting, in the step 2, the organic solvent is one or more of N-N dimethylformamide, N-N methylpyrrolidone and N-N dimethylacetamide.
Further limiting, the mass ratio of the modified ceramic powder to the organic solvent in the step 2 is 1: (10-30).
Further defined, the mass ratio of the polymer base material to acetone in step 3 is 1: (5-15).
Further limiting, the centrifugal rotating speeds in the step 1-2 are all 8000 r/min-12000 r/min.
Further limiting, the rotating speed of the magnetic stirring in the step 1-3 is 500 r/min-1500 r/min.
Further limiting, the coating in step 4 is specifically knife coating.
Compared with the prior art, the invention has the following remarkable effects:
according to the invention, the polymer is coated on the outer layer of the inorganic ceramic particles, the core-shell structure units which are uniformly coated are synthesized by self-assembly, and then the core-shell structure units are added into the polymer matrix to prepare the composite diaphragm with the core-shell structure, so that the diaphragm which has high mechanical strength, high wettability, good interface combination and can effectively inhibit lithium dendrites is realized. The core-shell composite diaphragm prepared by the method has the advantages of consistent appearance, high mechanical strength, high thermal stability, controllable pore diameter and porosity, can meet the application requirements of the diaphragm in the field of lithium ion batteries and energy, and has the following specific advantages:
1. the invention provides a core-shell structure composite diaphragm, which can ensure the stability of the diaphragm in the circulation process of a lithium ion battery at normal temperature and high temperature, and ceramic particles in the composite diaphragm cannot be displaced or scattered due to the influence of ion transmission, so that the composite diaphragm with a stable structure is formed.
2. The composite diaphragm with the core-shell structure provided by the invention not only ensures the original wettability of the diaphragm, but also improves the thermal stability and mechanical strength of the diaphragm.
3. The invention provides a preparation method of a core-shell structure composite diaphragm, which is simple and easy to realize, and is easy to realize direct matching with a new improved scheme of electrolyte and electrodes.
4. The composite diaphragm has the advantages of consistent appearance, high mechanical strength, high thermal stability and controllable porosity. The lithium iron phosphate anode lithium ion battery has good application effect, 600 cycles of discharge capacity of 140mAh/g under 1C, and in addition, 500 cycles of discharge capacity of 155mAh/g under 1C in a high-temperature or special environment, and the coulombic efficiency is up to 99.16%, and compared with a commercial battery and a battery capacity retention rate in domestic and foreign researches, the discharge capacity of the lithium iron phosphate anode lithium ion battery is obviously improved.
5. The composite diaphragm of the invention effectively improves the thermal stability, the thermal expansion rate at 150 ℃ is 2%, and the high-temperature performance of the battery is ensured.
Drawings
FIG. 1 is a transmission electron microscope morphology of the core-shell structured ceramic filler obtained in step 2 of example 2;
FIG. 2 is a high-resolution TEM morphology of the core-shell structured ceramic filler obtained in step 2 of example 2;
FIG. 3 is a graph representing thermal stability of separators according to examples of the present invention and comparative examples;
FIG. 4 is a graph representing mechanical strength of separators according to examples of the present invention and comparative examples;
FIG. 5 is a graph showing the absorption rate characteristics of electrolytes of separators according to examples of the present invention and comparative examples;
FIG. 6 is a graph representing wettability of separators according to an example of the present invention and a comparative example;
FIG. 7 is a graph representing the cycle performance at 1C for a lithium battery employing the separator of examples 1-3 at 80 ℃;
FIG. 8 is a graph of cycle performance characterization at 1C for lithium batteries of different separators at 25 ℃;
FIG. 9 is a graph showing the rate performance of lithium batteries with different separators at 25 ℃;
FIG. 10 is a graph of cycle performance characterization at 1C for lithium batteries of different separators at 80 ℃;
FIG. 11 is a graph representing coulombic efficiencies at 1C for lithium batteries with different separators at 80 ℃;
FIG. 12 is a graph showing the rate capability of lithium batteries with different separators at 80 ℃;
in FIGS. 3-12: celgard 2500-commercial polyolefin separator, PVDF-pure polyvinylidene fluoride of comparative example 1, Al2O3PVDF-directly doped alumina-polyvinylidene fluoride composite membrane of comparative example 2, APCS-5/PVDF-core-shell structure composite membrane of inventive example 1, APCS-10/PVDF-core-shell structure composite membrane of inventive example 2, APCS-15/PVDF-core-shell structure composite membrane of inventive example 3.
Detailed Description
The core-shell structure composite diaphragm of the embodiment 1 is prepared from a ceramic filler and a polymer substrate, the ceramic filler is uniformly dispersed in the polymer substrate, the ceramic filler is a core-shell structure composed of a ceramic core and a polymer shell, the polymer substrate is polyvinylidene fluoride, the mass fraction of the ceramic filler in the core-shell structure composite diaphragm is 5%, the ceramic core is alumina, the particle size of the ceramic core is 20nm, the polymer shell is polyvinylidene fluoride, and the mass ratio of the polymer shell to the ceramic core is 2: 1;
the preparation method of the core-shell structure composite membrane of preparation example 1 was carried out according to the following steps:
step 1: dispersing aluminum oxide in deionized water, magnetically stirring at normal temperature and 1000r/min for 6h, adding KH550, continuously magnetically stirring until the aluminum oxide is uniformly dispersed, centrifuging at 10000r/min, and drying to obtain modified ceramic powder; the mass ratio of the ceramic core material to the deionized water is 1: 30, wherein the mass ratio of the alumina to the KH550 is 5: 1;
step 2: dispersing the modified ceramic powder obtained in the step 1 into N-N dimethylformamide, then adding polyvinylidene fluoride, stirring at normal temperature for 12 hours, centrifuging at 10000r/min, drying, and ball-milling to obtain the core-shell structure ceramic filler; the mass ratio of the modified ceramic powder to the N-N dimethylformamide is 1: 15; the mass ratio of the modified ceramic powder to the polyvinylidene fluoride is 2: 1;
and step 3: dissolving polyvinylidene fluoride in acetone, magnetically stirring at 55 ℃ and 1000r/min for 30min to obtain a transparent colloidal solution, then continuously magnetically stirring at room temperature and 1000r/min for 1h, cooling to room temperature, adding the core-shell structure ceramic filler obtained in the step (2), and magnetically stirring at 1000r/min for 12h to obtain a mixed solution; the mass ratio of the polyvinylidene fluoride to the acetone is 1: 10;
and 4, step 4: and (4) carrying out blade coating on the mixed solution obtained in the step (3) to obtain the core-shell structure composite diaphragm with the thickness of 25 mu m.
Example 2, this example is different from example 1 in that: the mass fraction of the ceramic filler in the core-shell structure composite diaphragm is 10%. The other steps and parameters were the same as in example 1.
Example 3, this example is different from example 1 in that: the mass fraction of the ceramic filler in the core-shell structure composite diaphragm is 15%. The other steps and parameters were the same as in example 1.
Comparative example 1: the embodiment provides a polyvinylidene fluoride diaphragm, and a preparation method thereof is as follows:
and 2, placing the solution obtained in the step 1 on a coating machine, and setting a scraper at 400 mu m to obtain the pure polyvinylidene fluoride diaphragm with the thickness of 25 mu m.
Comparative example 2: the embodiment provides an alumina-polyvinylidene fluoride composite diaphragm, and a preparation method thereof is as follows:
and 3, placing the mixed solution obtained in the step 2 on a coating machine, and setting a scraper at 400 mu m to obtain the directly doped alumina-polyvinylidene fluoride composite diaphragm with the thickness of 25 mu m.
And (3) detection test: the core-shell structure composite membranes of examples 1 to 3, a commercial polyolefin membrane (Celgard2500) on the market, a pure polyvinylidene fluoride membrane of a comparative example 1 and a directly doped alumina-polyvinylidene fluoride composite membrane of a comparative example 2 were assembled in a lithium ion battery (CR2025) of a lithium iron phosphate positive electrode/lithium metal negative electrode, and then the performance of the assembled lithium ion battery was tested, specifically, the test process was as follows:
1. testing the electrochemical performance of the normal temperature/high temperature battery:
1mol/L LiPF is adopted as electrolyte at normal temperature6Dissolving the ethylene carbonate, the diethyl carbonate and the ethyl methyl carbonate in a mixed solvent consisting of the ethylene carbonate, the diethyl carbonate and the ethyl methyl carbonate, wherein the volume ratio of the ethylene carbonate, the diethyl carbonate and the ethyl methyl carbonate is 1:1: 1;
② the electrolyte adopts 1mol/L LiPF6Dissolving in ethylene carbonate, diethyl carbonate, propylene carbonate, diphenyl sulfone, vinylene carbonate and succinonitrile, wherein the ratio of ethylene carbonate: diethyl carbonate: propylene carbonate: diphenyl sulfone: vinylene carbonate: the volume ratio of the succinonitrile is 1:1:1:0.1: 0.1;
thirdly, the battery assembling process: the cell is assembled by using a CR2025 button cell, the electrolyte is used as an electrolyte, and the anode is lithium iron phosphate (LiFePO)4) Wherein the anode material is LiFePO with the mass ratio of 8:1:14Conductive carbon black, PVDF binder and lithium metal as a negative electrode.
Detecting parameters: after the battery is assembled, the battery is placed on a Xinwei battery testing system for testing, and the charging and discharging voltage range is 2.5V-4.2V.
2. And (3) testing mechanical properties: the mechanical strength of the separator was measured using a tensile tester. The separator was cut into a rectangular sheet of 2cm × 6cm, and sandwiched in a tensile tester, and the cross-sectional area of the separator and the thickness of the separator were input to form a tensile test curve, to obtain the mechanical strength of the separator.
3. And (3) testing thermal stability: the thermal imaging properties of the diaphragm were measured using a fourier thermography tester. The separator was cut into circular sheets of 16mm diameter with a substrate of 5cm x 5cm copper foil. As the temperature increases, heat is transferred through the copper foil to the diaphragm. Detecting infrared light of 7.5-13 μm to form an infrared image with a frequency of 7.5 Hz. The imaging was performed using a noise equivalent temperature difference mode and a 17 μm lens.
4. And (3) testing the absorption rate of the electrolyte: the mass of the diaphragm is weighed, the diaphragm is soaked in the electrolyte for 60min, the mass is weighed again every 5min, and the electrolyte absorption rate can be obtained by (the soaked mass-initial mass)/initial mass.
5. And (3) wettability testing: the contact angle test can be completed by a contact angle tester, the electrolyte is dropped on the diaphragm, and the wetting degree of the diaphragm can be observed by the tester.
The test results are shown in FIGS. 1-12 and Table 1:
as can be seen from fig. 1-2, the alumina is coated with polyvinylidene fluoride, which has a thickness of about 4nm to 5 nm.
As can be seen from fig. 3, the thermal shrinkage of the core-shell structure composite separator of the present invention is minimized with the increase of temperature, which indicates that the thermal stability is the highest, and the battery is ensured to be well cycled at high temperature.
As can be seen from FIG. 4, the mechanical strength of the composite diaphragm with the core-shell structure is 27MPa, which ensures the inhibition capability of lithium dendrite and the stability of the diaphragm in the battery operation process.
As can be seen from fig. 5, the electrolyte absorption of the core-shell structure composite diaphragm of the present invention is 240%, which ensures the electrolyte storage property of the diaphragm and can further improve the rate capability of the lithium ion battery.
As can be seen from FIG. 6, the contact angle of the core-shell structure composite membrane is the smallest (8 degrees), which ensures the property of the membrane for storing electrolyte and can further improve the rate capability of the lithium ion battery.
From fig. 7 to 12, it can be seen that the lithium ion battery with the core-shell structure composite diaphragm of the present invention has more excellent cycle performance and rate capability at both normal temperature and high temperature.
TABLE 1 Battery Performance test data
Claims (10)
1. The core-shell structure composite diaphragm is characterized by being prepared from a ceramic filler and a polymer substrate, wherein the ceramic filler is of a core-shell structure and is uniformly dispersed in the polymer substrate, and the ceramic filler is composed of a ceramic core and a polymer shell.
2. The core-shell structure composite diaphragm of claim 1, wherein the polymer substrate is one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trifluoroethylene, polyvinylidene fluoride-chlorotrifluoroethylene, polymethyl methacrylate, polyimide and polyacrylonitrile, and the mass fraction of the ceramic filler in the core-shell structure composite diaphragm is 5-15%.
3. The core-shell structure composite membrane according to claim 1, wherein the ceramic core is one or more of alumina, silica, zirconia, boron nitride, glass fiber, and layered silicate minerals, and the particle size of the ceramic core is 20nm to 200 nm.
4. The core-shell structure composite diaphragm of claim 1, wherein the polymer shell is one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate and polyimide, the mass ratio of the polymer shell to the ceramic core is (1.5-3): 1, and the thickness of the polymer shell layer is 4 nm-5 nm.
5. The preparation method of the core-shell structure composite membrane as claimed in any one of claims 1 to 4, wherein the preparation method is carried out according to the following steps:
step 1: dispersing the ceramic core material in deionized water, magnetically stirring at normal temperature until the ceramic core material is uniformly dispersed, then adding a cross-linking agent, continuously magnetically stirring until the ceramic core material is uniformly dispersed, centrifuging, and drying to obtain modified ceramic powder;
step 2: dispersing the modified ceramic powder obtained in the step 1 into an organic solvent, adding a polymer shell material, stirring at normal temperature until the modified ceramic powder is uniformly dispersed, centrifuging, drying and ball-milling to obtain the core-shell structure ceramic filler;
and step 3: dissolving a polymer substrate material in acetone, magnetically stirring at 50-70 ℃ to obtain a transparent colloidal solution, then continuously magnetically stirring at room temperature for 0.5-1 h, cooling to room temperature, adding the core-shell structure ceramic filler obtained in the step (2), and magnetically stirring for 6-12 h to obtain a mixed solution;
and 4, step 4: and (4) coating the mixed solution obtained in the step (3) to obtain the core-shell structure composite diaphragm.
6. The preparation method of the core-shell structure composite membrane according to claim 5, wherein the mass ratio of the ceramic core material to the deionized water in step 1 is 1: (20-50), wherein the mass ratio of the ceramic core material to the cross-linking agent in the step 1 is (2-20): 1, and the cross-linking agent in the step 1 is one of polyacrylonitrile, cellulose, citric acid, KH550, KH560 and KH 570.
7. The preparation method of the core-shell structure composite membrane according to claim 5, wherein the organic solvent in step 2 is one or more of N-N dimethylformamide, N-N methylpyrrolidone and N-N dimethylacetamide, and the mass ratio of the modified ceramic powder to the organic solvent in step 2 is 1: (10-30).
8. The preparation method of the core-shell structure composite membrane according to claim 5, wherein the mass ratio of the polymer base material to acetone in step 3 is 1: (5-15).
9. The preparation method of the core-shell structure composite diaphragm according to claim 5, wherein the centrifugal rotation speed in the step 1-2 is 8000r/min to 12000r/min, and the magnetic stirring rotation speed in the step 1-3 is 500r/min to 1500 r/min.
10. The preparation method of the core-shell structure composite membrane according to claim 5, wherein the coating in the step 4 is blade coating.
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| WO2024031519A1 (en) * | 2022-08-11 | 2024-02-15 | 宁德时代新能源科技股份有限公司 | Separator and preparation method therefor, and related secondary battery, battery module, battery pack and electric device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024031519A1 (en) * | 2022-08-11 | 2024-02-15 | 宁德时代新能源科技股份有限公司 | Separator and preparation method therefor, and related secondary battery, battery module, battery pack and electric device |
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| Publication number | Publication date |
|---|---|
| CN114171849B (en) | 2023-09-08 |
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