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Partition for lithium ion secondary battery

A secondary battery, lithium ion technology, used in secondary batteries, alkaline storage batteries, battery pack parts and other directions

Inactive Publication Date: 2003-11-05
TEIJIN LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, sometimes additional components are required to ensure the safety of the battery against abnormal heat release due to various reasons (nailing, external short circuit, etc.)

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0095] At 60°C, a PVdF copolymer with a weight average molecular weight Mw of 410,000 composed of 1,1-difluoroethylene: hexafluoropropylene: chlorotrifluoroethylene = 92.2: 4.4: 3.4 (weight ratio) was dissolved in a solution containing N, N - in a mixed solvent of dimethylacetamide (DMAc) and tripropylene glycol (TPG) (weight ratio 7 / 3), thereby preparing a film-forming coating solution (copolymer solution) with a copolymer concentration of 12% by weight. The obtained coating solution was used for dipping and coating the PE fine particle-attached nonwoven fabric in Comparative Example 1, and then the fabric was dipped in an aqueous solution having a solvent concentration of 50% by weight, coagulated, and then washed and dried to obtain a separator for a lithium ion secondary battery. The separator had an average thickness of 24.3 microns and a basis weight of 21.2 grams per square meter. The evaluation results of this separator are shown in Table 1.

Embodiment 2

[0097] A lithium ion secondary battery separator containing PET as both the main fiber and the binder fiber was prepared in the same manner as in Example 1, except that the nonwoven fabric in Example 1 was not coated with PE fine particles.

[0098] After drying the PE fine particle aqueous dispersion slurry used in Example 1, methanol was added to redisperse the PE fine particle, thereby obtaining a PE fine particle methanol-dispersion slurry. The slurry was coated on the surface of a lithium ion secondary battery separator and dried to attach PE fine particles to the surface of the separator, thus obtaining the lithium ion secondary battery separator of the present invention.

[0099] The average thickness of the obtained separator was 24.5 microns, the basis weight was 20.5 g / m2, and the coverage of PE fine particles was 5.1 g / m2. The evaluation results of this separator are shown in Table 1.

Embodiment 3

[0101] The same nonwoven fabric as in Example 1 was used. The PE fine particle aqueous dispersion slurry used in Example 1 was dried to obtain PE fine particles. The PE fine particles were dispersed in the same type of film-forming coating liquid as in Example 1 in the same amount as the PVdF copolymer to obtain a film-forming coating liquid. In the same manner as in Example 1, this coating solution was used to prepare a lithium ion secondary battery separator. The obtained separator had an average thickness of 25.6 µm, a basis weight of 21.5 g / m 2 , and a coverage of PE fine particles of 6.1 g / m 2 . The evaluation results of this separator are shown in Table 1.

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Abstract

Separator for a lithium ion secondary battery generating electromotive force by lithium doping / dedoping, said separator being composed of an organic polymer contained in an electrolytic solution that can swell to retain the electrolytic solution (component A) and is composed of a porous film surrounding a non-woven fabric which is not swellable in the electrolytic solution, the porous film comprising an organic polymer (component B) which is not swellable in the electrolytic solution and has a melting point of 210° C. or more and . An organic polymer (component C) having a melting point of 180° C. or less, wherein component B is added to fibers constituting the nonwoven fabric. The separator is highly safe and exhibits low degradation of mechanical properties towards organic solvents.

Description

technical field [0001] The present invention relates to separators used in lithium ion secondary batteries. Background technique [0002] In recent years, with the development of portable electronic devices, lithium-ion secondary batteries that generate electromotive force through lithium doping / dedoping have been widely used because of their particularly high energy density. For lithium-ion secondary batteries, in order to obtain higher performance, it has been proposed to use organic polymers such as polyethylene oxide (PEO), polyacrylonitrile (PAN), Separators of polymethyl methacrylate (PMMA) or polyvinylidene fluoride (PVdF). From the viewpoint of oxidation / reduction resistance, among these polymers, PVdf or PVdf copolymers mainly composed of PVdf are considered to be the most suitable, and some of these have been put into practice. [0003] It is known that a separator using such an organic polymer has insufficient mechanical properties and is difficult to form a thi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/24H01M50/417H01M50/42H01M50/423H01M50/426H01M50/443
CPCH01M10/0525H01M10/4235H01M2300/0091H01M2300/0094Y02E60/10H01M50/44H01M50/417H01M50/443H01M50/423H01M50/426H01M50/42H01M50/449H01M50/491H01M50/414H01M50/489H01M50/463
Inventor 西川聪本元博行大道高弘
Owner TEIJIN LTD
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