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Lithium battery diaphragm and preparation method thereof

A diaphragm and lithium battery technology, which is applied in the field of new structure lithium battery diaphragm and its preparation, can solve the problems of low battery charge retention, large surface pore size, high porosity, etc., and achieve improved battery safety, strong low temperature performance, and porosity high effect

Inactive Publication Date: 2021-12-14
潘巧珍
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since this electrospun nanofiber separator is a non-woven fabric stacked by fibers, it has too high porosity and too large surface pore size, resulting in a low charge retention rate of the battery and frequent micro-short circuits. Especially when the thickness of the battery separator is low, such as below 20 microns, the probability of this situation is quite high

Method used

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  • Lithium battery diaphragm and preparation method thereof
  • Lithium battery diaphragm and preparation method thereof

Examples

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Effect test

Embodiment 1

[0024] A preparation method of a lithium battery diaphragm, comprising the steps of:

[0025] (1) Preparation of film-forming solution: select polyacrylonitrile powder (molecular weight is about 80,000) as sacrificial resin, mix it with polytetrafluoroethylene resin powder with an average particle diameter of 100nm in a mass ratio of 1:5, and then The solvent dimethylformamide is added to prepare a film-forming solution with a total mass concentration of 18%, which is ready for use after defoaming;

[0026] (2) The film-forming solution prepared in step (1) is scraped with a scraper on the surface of a clean glass plate to form a liquid film with a thickness of 50 μm, and then left to stand for 20 seconds at room temperature and in an environment with a humidity of 80%, and then the above-mentioned The glass plate carrying the liquid film was placed in excess deionized water and allowed to stand for 48 hours, then the resin film was peeled off from the surface of the glass pla...

Embodiment 2

[0030] A preparation method of a lithium battery diaphragm, comprising the steps of:

[0031] (1) Preparation of film-forming solution: select polyvinylidene fluoride powder (about 420,000 molecular weight) as the sacrificial resin, mix it with polytetrafluoroethylene resin powder with an average particle size of 200nm in a mass ratio of 1:10, and then Add the solvent dimethylacetamide to prepare a film-forming solution with a total mass concentration of 25%, and mechanically stir for 24 hours to defoam and set aside;

[0032] (2) Scrape the film-forming solution prepared in step (1) into a liquid film with a thickness of 32 μm on the surface of a clean glass plate, then leave it for 10 seconds at room temperature and in an environment with a humidity of 50%, and then apply the above-mentioned The glass plate carrying the liquid film was placed in excess deionized water and allowed to stand for 48 hours, then the resin film was peeled off from the surface of the glass plate, d...

Embodiment 3

[0036] A preparation method of a lithium battery diaphragm, comprising the steps of:

[0037] (1) Preparation of film-forming solution: choose polyethylene powder (about 1.2 million molecular weight) as a sacrificial resin, mix it with polytetrafluoroethylene resin powder at a mass ratio of 4:1, and then add solvent xylene to prepare the total mass The film-forming solution with a concentration of 15% was mechanically stirred for 2 hours and degassed for later use;

[0038] (2) The film-forming solution prepared in step (1) is scraped with a scraper to make a liquid film with a thickness of 80 μm on the surface of a clean glass plate, and then left to stand for 30 seconds at 60° C. and a humidity of 90%, and then The above-mentioned glass plate carrying the liquid film was placed in excess deionized water and allowed to stand for 36 hours, then the resin film was peeled off from the surface of the glass plate, dried at 60°C, and set aside;

[0039] (3) Put the resin film drie...

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Abstract

The invention relates to the field of lithium battery diaphragm preparation, in particular to a lithium battery diaphragm and a preparation method thereof. The lithium battery diaphragm is a polytetrafluoroethylene porous membrane with a micropore structure, and the preparation method mainly comprises the steps of membrane forming solution preparation, solution phase conversion membrane forming, membrane structure high-temperature conversion, membrane aftertreatment and the like. The lithium battery diaphragm provided by the invention is mainly composed of polytetrafluoroethylene resin, has high porosity and developed microporous structure, has better mechanical properties and high and low temperature resistance than a traditional polyolefin diaphragm, realizes multiple effects of optimizing the diaphragm structure, improving the diaphragm performance and reducing the diaphragm cost, and has good application prospects in the field of high-performance lithium batteries. The preparation technology is simple and easy to implement, low in cost, environmentally friendly and beneficial to large-scale popularization.

Description

technical field [0001] The invention belongs to the technical field of lithium battery diaphragm preparation, and in particular relates to a lithium battery diaphragm with a new structure and a preparation method thereof. Background technique [0002] In lithium batteries, the main function of the separator is to keep the positive and negative electrodes separated to prevent short circuits while allowing rapid transfer of electrolyte ions, which is an important part of lithium-ion batteries. The performance of the separator will directly affect the characteristics of the battery, such as the capacity, internal resistance, rate, cycle and self-discharge of the battery. At present, polyolefin diaphragms are widely used in lithium-ion battery diaphragm materials due to their good mechanical properties, chemical stability, and high-temperature self-closing properties, but their heat shrinkage resistance and flame retardancy are poor. At this time, the separator is prone to ther...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M50/403H01M50/417H01M50/426H01M50/491H01M10/052H01M10/0525
CPCH01M10/052H01M10/0525Y02E60/10
Inventor 潘巧珍陈俊孚李娇任嵬
Owner 潘巧珍
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