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Aramid fiber phase-inversion coating lithium ion battery diaphragm and preparation method thereof

A technology for lithium-ion batteries and diaphragms, applied in secondary batteries, battery pack components, circuits, etc., can solve the problems of uniform and stable lithium-ion battery diaphragms, poor thermal stability, and difficult preparation steps, etc., to improve plugging effect, reducing interface impedance, and improving conductivity

Inactive Publication Date: 2020-07-03
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] However, there are defects in the above-mentioned prior art. The ion migration efficiency of the aramid-coated lithium-ion battery separator in the prior art is low, and the thermal stability is relatively poor. In addition, it is difficult to obtain a relatively uniform and stable lithium-ion battery separator in the preparation steps.
[0008] This application aims to solve the related problems in the prior art, such as the low ion migration efficiency of the aramid-coated lithium-ion battery diaphragm, poor thermal stability, and insufficient uniformity and stability of the diaphragm.

Method used

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  • Aramid fiber phase-inversion coating lithium ion battery diaphragm and preparation method thereof
  • Aramid fiber phase-inversion coating lithium ion battery diaphragm and preparation method thereof
  • Aramid fiber phase-inversion coating lithium ion battery diaphragm and preparation method thereof

Examples

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Effect test

Embodiment 1

[0051] 8.3 grams of meta-aramid fibers, 1.5 grams of cosolvent calcium chloride, 1.2 grams of fluororesin polyvinylidene fluoride-hexafluoroethylene copolymer and 0.5 grams of pore-forming agent polyethylene glycol were added to 86.5 grams of dimethylacetamide, After stirring at 80°C, a uniformly mixed coating solution was obtained. A 16 μm polyethylene diaphragm was selected as the substrate, and the cooled coating solution was coated on one side of the polyethylene diaphragm, and quickly transferred to a coagulation bath composed of absolute ethanol and water. Medium (the mass ratio of absolute ethanol is 87.66%). After standing still for 3 minutes, transfer to pure water to remove excess absolute ethanol, and dry at 60° C. to obtain a finished film.

Embodiment 2

[0053] 7.2 grams of meta-aramid fiber, 1 gram of cosolvent calcium chloride, 1.5 grams of fluororesin polyvinylidene fluoride-hexafluoroethylene copolymer and 2.5 grams of pore-forming agent polyethylene glycol were added to 90.5 grams of nitrogen methyl pyrrolidone, 80 After stirring at ℃ to obtain a uniformly mixed coating solution, select a 16 μm polyethylene diaphragm as the base material, apply the cooled coating solution on one side of the polyethylene diaphragm, and quickly transfer it to a coagulation bath composed of absolute ethanol and water (the mass ratio of absolute ethanol is 80.62%). After standing still for 3 minutes, transfer to pure water to remove excess absolute ethanol, and dry at 60° C. to obtain a finished film.

Embodiment 3

[0055] Add 8.3 grams of meta-aramid fiber, 1.5 grams of cosolvent lithium chloride, 0.8 grams of fluororesin polyvinylidene fluoride and 2 grams of pore-forming agent polyvinylidene fluoride to 87.4 grams of dimethylacetamide, and stir at 80°C to obtain a mixture For a uniform coating solution, a 16 μm polyethylene diaphragm is selected as the base material, and the cooled coating solution is coated on one side of the polyethylene diaphragm, and quickly transferred to a coagulation bath mixed with dimethylacetamide and water (dimethylacetamide The mass ratio of dimethylacetamide is 57.43%), after standing for 2 minutes, transfer to pure water to remove excess dimethylacetamide solvent, and dry at 60°C to obtain a finished film.

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Abstract

The invention relates to a preparation method of an aramid fiber phase-inversion coating lithium ion battery diaphragm, which is characterized by comprising the following steps: (1) dissolving aramidfiber, a cosolvent, an oily assistant and a pore-forming agent in a first solvent at 60-100 DEG C to prepare a uniformly mixed coating solution; (2) coating one side or two sides of a diaphragm base material with the coating liquid, immersing the mixture into a coagulating bath consisting of a second solvent and water for phase inversion for 1-3 minutes, then immersing the mixture into pure waterto remove the redundant solvent, and drying to obtain a finished product of the lithium ion battery diaphragm; the surface of the diaphragm is coated with the high-temperature-resistant polymer, so that the thermal stability and the mechanical strength of the diaphragm are improved; a water-soluble pore-forming agent is used in the coating liquid, and pores are uniformly formed after phase inversion of a coating layer; and the used oily auxiliary agent reduces the interface impedance on the basis of maintaining the main body skeleton structure of the aramid fiber, improves the conductivity oflithium ions, and improves the hole plugging effect caused by oily coating.

Description

technical field [0001] The invention relates to a lithium-ion battery diaphragm, in particular to a lithium-ion battery diaphragm with fluororesin and aramid fiber blended phase-inversion coating, a preparation method thereof, and an application of the diaphragm in a lithium-ion battery diaphragm. Background technique [0002] Lithium-ion batteries have become an important energy storage device in the world due to their advantages such as high energy density, low self-discharge, and long service life, and are used in a wide range of products such as smartphones, notebook computers, and new energy vehicles. In recent years, my country has attached great importance to the development of lithium-ion batteries. The "Made in China 2025" plan proposes that the energy density of lithium-ion batteries will reach 300Wh / kg by 2020, 400Wh / kg by 2025, and 500Wh / kg by 2030. With the high requirements for energy density, lithium-ion batteries will tend to use high-energy active materials ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/14H01M2/16H01M10/0525H01M50/403H01M50/411H01M50/449H01M50/489H01M50/497
CPCH01M10/0525H01M50/411H01M50/44H01M50/403H01M50/449Y02E60/10
Inventor 王海辉黄子宇王素清
Owner SOUTH CHINA UNIV OF TECH
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