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Three-layer co-extrusion diaphragm for lithium battery and stretching process of three-layer co-extrusion diaphragm

A three-layer co-extrusion, lithium battery technology, used in lithium batteries, battery pack components, non-aqueous electrolyte batteries, etc., can solve the problems of difficult closed-cell temperature control, poor uniformity of microporous structure, and difficult processing. Achieve the effect of meeting the needs of continuous production, high production efficiency, and narrow pore size distribution

Active Publication Date: 2021-11-16
JIESHOU CITY TIANHONG PACKAGING MATERIAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Among them, the three-layer PP / PE / PP composite separator is widely used as a battery separator due to its excellent mechanical properties and corrosion resistance. However, the three-layer PP / PE / PP composite separator is difficult to process, and the uniformity of the formed micropore structure is poor. Temperature control is difficult, which brings certain difficulties to its application

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Homopolypropylene and 3-ethyl-3-hydroxymethyloxetane are mixed in a mass ratio of 60:1, banburyed in an internal mixer at 180°C for 30 minutes, extruded and granulated to obtain PP material.

[0028] The low-density polyethylene powder with particle size of 0.5-1um and melt index of 2-4g / min is crosslinked by electron beam irradiation technology, and the irradiation dose is 16KGy to make surface crosslinked crosslinked polyethylene. The degree of cross-linking of polyethylene molecules is greater than the degree of internal cross-linking.

[0029] After uniformly mixing 40 parts of low-density polyethylene with a melt index of 1-2 g / min and 15 parts of poly-1,4-cyclohexanedimethylene terephthalate in parts by weight, add 3-ethyl-3-hydroxy 3 parts of methyloxetane were mixed in an open mill at 160° C. for 1.5 hours, and then granulated by a granulator to obtain modified polyethylene. The heat-resistant temperature of poly-1,4-cyclohexanedimethylene terephthalate is high...

Embodiment 2

[0034] Homopolypropylene and 3-ethyl-3-hydroxymethyloxetane are mixed in a mass ratio of 60:2, internally kneaded in an internal mixer at 180°C for 30 minutes, extruded and granulated to obtain PP material.

[0035] The low-density polyethylene powder with particle size of 0.5-1um and melt index of 2-4g / min is crosslinked by electron beam irradiation technology, and the irradiation dose is 16KGy to make surface crosslinked crosslinked polyethylene. The degree of cross-linking of polyethylene molecules is greater than the degree of internal cross-linking.

[0036] After uniformly mixing 50 parts of low-density polyethylene with a melt index of 1-2 g / min and 25 parts of poly(1,4-cyclohexanedimethylene terephthalate) by weight, add 3-ethyl-3-hydroxy 8 parts of methyloxetane were mixed in an open mill at 180°C for 1, and then granulated with a granulator to obtain modified polyethylene. The heat-resistant temperature of poly-1,4-cyclohexanedimethylene terephthalate is higher than...

Embodiment 3

[0041] The low-density polyethylene powder with particle size of 0.5-1um and melt index of 2-4g / min is crosslinked by electron beam irradiation technology, and the irradiation dose is 16KGy to make surface crosslinked crosslinked polyethylene. The degree of cross-linking of polyethylene molecules is greater than the degree of internal cross-linking.

[0042] After uniformly mixing 50 parts of low-density polyethylene with a melt index of 1-2 g / min and 21 parts of poly(1,4-cyclohexanedimethylene terephthalate) by weight, add 3-ethyl-3-hydroxy 6 parts of methyl oxetane were mixed in an open mill at 160° C. for 1.5 hours, and then granulated by a granulator to obtain modified polyethylene. The heat-resistant temperature of poly-1,4-cyclohexanedimethylene terephthalate is higher than that of polyethylene.

[0043] Stir and mix 70 parts of modified polyethylene and 1.8 parts of polyethylene wax evenly, mix in an internal mixer at 180°C for 40 minutes, then add 22 parts of cross-li...

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Abstract

The invention discloses a three-layer co-extrusion diaphragm for lithium battery and a stretching process of the three-layer co-extrusion diaphragm, and the stretching process comprises the following steps: S1, respectively melting a PP material and a PE material in a vacuum state, conveying the melted materials to a three-layer co-extrusion die head for extrusion, forming a three-layer composite material on a casting roller, and quenching the three-layer composite material to 20-40 DEG C by using airflow so as to facilitate transmission, wherein the middle layer of the three-layer composite material is a PE layer formed by a PE material, the two sides of the three-layer composite material are PP layers formed by a PP material, the thickness of the three-layer composite material is 80-100 microns, and the humidity of the air flow is 90-100%; S2, heating the three-layer composite material to 80-90 DEG C and performing longitudinal stretching by 1.0-1.5 times to form a first-stage stretched diaphragm; S3, cooling the first-stage stretching diaphragm to 50-70 DEG C, longitudinally stretching the first-stage stretching diaphragm by 2-3 times to form a microporous structure on the surface of the first-stage stretching diaphragm, and rolling the first-stage stretching diaphragm to obtain the three-layer co-extrusion diaphragm with the thickness of 25-35 [mu]m. The method overcomes the defects in the prior art, meets the continuous production requirements of factories, and is high in production efficiency, high in puncture strength and porosity of the produced diaphragm and suitable for large-scale production; and the aperture distribution range is narrow.

Description

technical field [0001] The invention relates to the technical field of battery separators, in particular to a three-layer co-extruded separator for lithium batteries and a stretching process thereof. Background technique [0002] In recent years, the lithium-ion battery technology has developed rapidly. As one of the core materials in the battery, the separator determines the performance of the lithium-ion battery. Therefore, the separator material and preparation technology urgently need to be studied in depth. At present, the commercial lithium battery separator is mainly polyolefin separator, and the preparation process is transitioning from dry method to wet method, but in recent years, separators with different material systems and different preparation processes have been developed. [0003] As the key material of lithium batteries, the diaphragm plays the role of electronic isolation in the battery, preventing direct contact between the positive and negative electrode...

Claims

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Application Information

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IPC IPC(8): H01M50/403H01M50/457H01M50/489H01M50/491H01M10/052
CPCH01M50/403H01M50/457H01M50/489H01M50/491H01M10/052Y02E60/10
Inventor 胡伟吴磊李汪洋张德顺何祥燕杨建军张建安陈曼刘久逸吴庆云吴明元彭盼盼吴爱平朱江森郭浩孙晓华王若愚
Owner JIESHOU CITY TIANHONG PACKAGING MATERIAL