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Preparation method of PVDF (polyvinylidene fluoride) mixture lithium-ion battery separator

A lithium-ion battery, polyvinylidene fluoride technology, applied in battery pack parts, circuits, electrical components, etc., can solve the problems of uneven micropore diameter of diaphragm, poor mechanical performance of diaphragm, low ionic conductivity, etc. Physical and electrochemical properties cannot be achieved simultaneously, parameters are easy to control, and the preparation process is simple.

Inactive Publication Date: 2015-04-01
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above formula enhances the strength of the membrane, and the separator basically meets the requirements of the lithium-ion battery for the separator, but there are the following defects: the pore size of the formed separator is not uniform, resulting in low ion conductivity and affecting its performance in the battery
[0007] Japanese Laid-Open Patent No. 2005-209570 discloses that heat-resistant resin solutions such as aromatic polyamides, polyimides, polyethersulfones, polyetherketones, and polyetherimides having a melting point of 200° C. Coating on both sides of the polyolefin diaphragm, immersing it in the coagulation solution, washing with water, and drying to prepare a polyolefin diaphragm coated with a heat-resistant resin, but the diaphragm prepared by this method often has poor mechanical properties and poor ion conductivity. Low rate and other issues

Method used

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  • Preparation method of PVDF (polyvinylidene fluoride) mixture lithium-ion battery separator

Examples

Experimental program
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Effect test

Embodiment 1

[0029] (1) Selection of solvent: The solvent is DMAc.

[0030] (2) Preparation of the original casting solution: first measure 76.2g of DMAc, add the pore-forming agent PVP at a mass percentage of 4.0 to form a mixed solution, then add PVDF at a mass percentage of 15.0, and then add HDPE and PSF at a mass percentage of 1.4 And 3.4 mass percent is added.

[0031] (3) Preparation of homogeneous casting solution: heat the original casting solution in a heater at 65°C for 7 hours, then stir with a magnetic stirrer, stir for 2 hours and then let it stand for 24 hours defoaming.

[0032] (4) Basement film casting: Cast the obtained homogeneous casting film on a clean and smooth glass plate after drying with absorbent cotton, and adjust the scraper parameters to scrape the film.

[0033] (5) Phase separation: The film obtained after scraping was immersed in deionized water for phase separation to form pores and left for 24 hours.

[0034] (6) Membrane drying: After standing still,...

Embodiment 2

[0036] (1) Selection of solvent: The solvent is DMAc.

[0037] (2) Preparation of the original casting solution: first measure 86.2g of DMAc, add the pore-forming agent PVP at a mass percentage of 1.0 to form a mixed solution, then add PVDF at a mass percentage of 10.0, and then add HDPE and PSF at a mass percentage of 1.2 And 1.6 mass percent is added.

[0038] (3) Preparation of homogeneous casting solution: heat the original casting solution in a heater at 78°C for 5 hours, then stir with a magnetic stirrer for 2.5 hours and then static for 24 hours. Set for defoaming.

[0039] (4) Basement film casting: Cast the obtained homogeneous casting film on a clean and smooth glass plate after drying with absorbent cotton, and adjust the scraper parameters to scrape the film.

[0040] (5) Phase separation: The film obtained after scraping was immersed in deionized water for phase separation to form pores and left for 24 hours.

[0041] (6) Membrane drying: After standing still, ...

Embodiment 3

[0043] (1) Selection of solvent: The solvent is DMF.

[0044] (2) Preparation of the original casting solution: first measure 80.2g of DMAc, add the pore-forming agent PVP at a mass percentage of 3.0 to form a mixed solution, then add PVDF at a mass percentage of 12.0, and then add HDPE and PSF at a mass percentage of 1.4 And 3.4 mass percent is added.

[0045] (3) Preparation of homogeneous casting solution: heat the original casting solution in a heater at a heating temperature of 70°C for 6 hours, then stir with a magnetic stirrer for 2.5 hours and then static for 24 hours. Set for defoaming.

[0046] (4) Casting of base film: cast the obtained homogeneous casting solution on a clean and smooth glass plate after drying with absorbent cotton, and adjust the parameters of the scraper to scrape the film.

[0047](5) Phase separation: The film obtained after scraping was immersed in deionized water for phase separation to form pores and left for 24 hours.

[0048] (6) Membra...

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Abstract

The invention relates to a preparation method of a PVDF (polyvinylidene fluoride) pore membrane material used for a lithium-ion battery separator. With adoption of an NIPS (nonsolvent-induced phase separation) method, PVDF, HDPE (high-density polyethylene), PSF (polysulfone) and PVP (polyvinyl pyrrolidone) are proportionally mixed, heated and dissolved in a solvent, and a casting solution is obtained; the casting solution form a basic membrane through tape casting, the obtained basic membrane is immersed into deionized water or an organic solventnormal hexane, cyclohexane, absolute ethyl alcohol, methyl alcoholtoluene or xylene, the solvent in the separator is removed, vacuum drying is performed, and the separator is formed. The method has a simple process, parameters are easy to control, and compared with an ordinary commercial separator, physical properties of wettability, mechanical property, ionic conductivity and the like as well as electrochemical properties of electrochemical stability, rate capability and the like of the prepared PVDF mixture lithium-ion battery separator are greatly improved.

Description

technical field [0001] The invention relates to a preparation technology of a polymer functional film, in particular to a lithium-ion battery separator [0002] The preparation method of the polyvinylidene fluoride mixture microporous membrane material of the membrane. Background technique [0003] With the increasing trend such as higher performance, lighter weight, and automotive power supplies, secondary batteries such as lithium-ion secondary batteries, lithium polymer secondary batteries, and supercapacitors (electric double-layer capacitors and the like) are required to have High energy density, large capacity and good safety performance. Among them, the lithium-ion battery separator plays an extremely critical and important role. The separator is located between the anode and cathode of the battery, acts as an insulator, and provides a path for ion conduction by maintaining the electrolyte. If the temperature of the battery becomes too high, in order to cut off the ...

Claims

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Application Information

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IPC IPC(8): C08J9/26C08J5/18C08L27/16C08L23/06C08L81/06H01M2/16H01M50/403
CPCY02E60/10
Inventor 刘久清何俊颖
Owner CENT SOUTH UNIV
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