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Lithium ion battery diaphragm coating, and preparation method and application thereof

A lithium-ion battery and separator technology, applied in coatings, battery pack components, circuits, etc., can solve problems such as internal temperature rise, battery short circuit, melting of PP layer, etc., to enhance thermal dimensional stability and improve safety. , the effect of improving heat resistance and stability

Active Publication Date: 2016-12-14
GUANGDONG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the current commercial lithium-ion battery separator still has the following defects: First, the melting point of PE is 120 ° C, and the melting point of PP is 160 ° C. The difference between the melting points of the two is not very large. When the temperature reaches the thermal shutdown temperature, Due to the thermal hysteresis effect of the battery, the internal temperature will further increase to reach the melting point of PP, and the PP layer will also melt, resulting in a short circuit inside the battery
Second, when the temperature rises, even if PE realizes the thermal shutdown function, the thermal shrinkage of the separator at high temperature will make the positive and negative poles of the battery contact and cause an internal short circuit
Conventional separators can protect lithium batteries from unsafe behaviors induced by overcharge, short circuit, extrusion and other factors, but they have not fundamentally solved the safety problem of batteries.

Method used

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  • Lithium ion battery diaphragm coating, and preparation method and application thereof
  • Lithium ion battery diaphragm coating, and preparation method and application thereof
  • Lithium ion battery diaphragm coating, and preparation method and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] 1. Preparation:

[0041] S1. Measure the ethanol of 160ml and the tetraethyl orthosilicate of 8ml respectively in the flask, extract the ammoniacal liquor of 8ml and inject in the above-mentioned flask that reaction solution is housed, with After magnetic stirring at 35°C for 24 hours, light blue nano-SiO 2Dispersions;

[0042] S2. Weigh 1.2mg of 3-(trimethoxysilyl)propyl-2-methyl-2-acrylate silane coupling agent (MPS) and dissolve it in 20ml of ethanol, and slowly drop it by titration Add it to the above light blue dispersion and continue to react for 24 hours to obtain in-situ modified SiO 2 ethanol dispersion;

[0043] S3. the resulting modified SiO 2 The ethanol dispersion was centrifuged several times with methanol and deionized water, and finally the centrifuged SiO 2 Disperse in 100ml of deionized water to prepare 0.7mg / ml SiO 2 water dispersion;

[0044] S4. To the modified SiO of step S1 2 Add 8.9ml of styrene, 1.1ml of n-butyl acrylate, 0.03g of sodiu...

Embodiment 2

[0052] The difference from Example 1 is that 8ml of styrene, 2ml of n-butyl acrylate, 0.05g of emulsifier sodium dodecylbenzenesulfonate, and 0.4g of buffering agent sodium bicarbonate are added in step S4. Emulsion of silica coated with styrene copolymerized n-butyl acrylate.

[0053] The average particle diameter of the obtained polystyrene copolymerized n-butyl acrylate-coated silica particles with a core-shell structure was determined to be 200 nm; the measured glass transition temperature of the coating was 75° C., and the thermal shutdown temperature was 75° C.

Embodiment 3

[0055] The difference from Example 1 is that 7.3ml of styrene, 2.7ml of n-butyl acrylate, 0.1g of emulsifier sodium dodecylbenzenesulfonate, and 0.8g of buffering agent sodium bicarbonate were added in step S4 to obtain a core-shell structure Polystyrene copolymer n-butyl acrylate coated silica emulsion.

[0056] The obtained polystyrene copolymerized n-butyl acrylate-coated silica particles with a core-shell structure have an average particle diameter of 300 nm, the measured glass transition temperature of the coating is 62°C, and the thermal shutdown temperature is 62°C.

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Abstract

The invention discloses a lithium ion battery diaphragm coating, and a preparation method and application thereof. The battery diaphragm coating is a coating which coats the surface of the lithium battery diaphragm by a spin-coating method. The lithium ion battery diaphragm coating is prepared by the steps of: coating the surface of modified SiO2 which serves as a core with a macromolecular copolymer by emulsion polymerization to obtain a nanoparticle emulsion with silicon dioxide coated by a shell-core polymer; and thickening by hydroxyethyl cellulose, wherein the macromolecular copolymer is a polystyrene / poly butyl acrylate or polystyrene / polymethyl acrylate copolymer. The coating prepared by the method provided by the invention has low-temperature thermal shunt-down and high-temperature shrinkage-resistant double-protection functions on the lithium battery diaphragm, improves the safety of the lithium ion battery and can be widely applied in the field of the lithium ion battery diaphragm.

Description

technical field [0001] The invention belongs to the technical field of coating preparation, and in particular relates to a preparation method and application of a coating with thermal shutdown function for lithium-ion battery separators. Background technique [0002] Due to the advantages of high energy density, low self-discharge, no memory effect and stable discharge voltage platform, lithium-ion batteries have gradually replaced traditional fossil materials and become the main choice for power batteries. The diaphragm is a key component of a lithium-ion battery, known as the "third pole of a lithium-ion battery". Its main function in the battery is to block the conductance of the positive and negative electrons and allow ions to pass through freely, thereby realizing the important role of ion conduction. It is an important determinant of battery capacity, cycle capability and safety performance. As we all know, when a lithium battery is overloaded or overcharged, it will...

Claims

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Application Information

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IPC IPC(8): C09D151/10C09D101/28C09D5/18C08F292/00C08F212/08H01M2/14H01M2/16
CPCC08F292/00C08L2201/08C08L2203/206C09D5/18C09D151/10H01M50/403H01M50/411H01M50/446H01M50/449C08L1/284C08F212/08Y02E60/10
Inventor 廖海洋张海燕秦改洪浩群
Owner GUANGDONG UNIV OF TECH
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