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Polyester microporous separator for secondary lithium battery and preparation method thereof

A technology for secondary lithium batteries and microporous separators, applied in battery pack parts, circuits, electrical components, etc., can solve the problems of high thermal shrinkage rate and decreased air permeability, and achieve simple production process and low high temperature thermal shrinkage rate. , a wide range of effects

Active Publication Date: 2016-01-20
四川东方绝缘材料股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The present invention aims at the shortcomings of existing polyolefin separators such as high thermal shrinkage rate and decreased air permeability at temperatures above 160°C, and provides a single-layer polyester material as the base material, which can meet the normal conditions of lithium batteries at temperatures above 160°C. Polyester microporous diaphragm for secondary lithium battery with safe operation and preparation method thereof

Method used

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  • Polyester microporous separator for secondary lithium battery and preparation method thereof
  • Polyester microporous separator for secondary lithium battery and preparation method thereof
  • Polyester microporous separator for secondary lithium battery and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1-1、1-2

[0033] After drying the components with a certain proportion in Table 1 under different conditions, the twin-screw extruder was melted and kneaded at 280°C and then extruded and cut into granules, and the obtained granules were dried again to After the moisture content is 200ppm, put it into a single-screw extruder to melt, knead and extrude it at 280°C, cool it with a cold drum at 20°C-40°C and cast it into a thick sheet with a thickness of 0.2-0.3mm. After stretching 2 times in the longitudinal direction at 135°C, preheat in the drying tunnel at 135°C, perform simultaneous biaxial stretching at 135°C, stretch 2 times in the longitudinal direction and 2.5 times in the transverse direction, and then heat-setting at 135°C , to obtain a polyester microporous separator.

Embodiment 2-1、2-2

[0035] After drying the components with a certain proportion in Table 1 under different conditions, the twin-screw extruder melted and kneaded at 275 ° C and then extruded and cut into granules, and the obtained granules were dried again to After the moisture content is 200ppm, put it into a single-screw extruder to melt, knead and extrude it at 275°C, then cool it with a cold drum at 20°C to 40°C and cast it into a thick sheet with a thickness of 0.2 to 0.3mm. After stretching 2 times in the longitudinal direction at low temperature, it is preheated through the drying tunnel at 110°C, and then the biaxial stretching is carried out simultaneously at 110°C, stretching 2 times in the longitudinal direction and 3 times in the transverse direction, and then heat-setting at 145°C. A polyester microporous separator was obtained.

Embodiment 3-1、3-2

[0037] After drying the various components with a certain proportion and number given in Table 1 under different conditions, the twin-screw extruder melted and kneaded at 285 ° C and then extruded and cut into granules, and the obtained granules were dried again to After the moisture content is 200ppm, put it into a single-screw extruder to melt, knead and extrude at 285°C, cool it with a cold drum at 20°C to 40°C and cast it into a thick sheet with a thickness of 0.2 to 0.3mm. After stretching 2 times in the longitudinal direction at 115°C, preheat the drying tunnel at 115°C, perform simultaneous biaxial stretching at 115°C, stretch 2 times in the longitudinal direction and 2.8 times in the transverse direction, and then heat-setting at 150°C. A polyester microporous separator was obtained.

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Abstract

The invention discloses a polyester microporous diaphragm for a secondary lithium battery, which is characterized in that the mass percentage of the diaphragm consists of 40-79% polymer A, 15-30% polymer B, and 5-15% compatibilizer and 1-15% pore-forming agent; the thickness of the diaphragm is 0.01-0.05mm; the preparation method of the diaphragm is to mix polymer A, polymer B, compatibilizer and pore-forming agent, and melt and mix them through a twin-screw extruder. Refining, granulating, drying, then melt extrusion through a single-screw extruder, cold drum casting, longitudinal stretching at 80°C-150°C for 2-8 times, and then synchronous longitudinal stretching at 80°C-150°C 2 to 6 times and 1.5 to 8 times of transverse stretching, heat setting treatment, that is, the polyester microporous diaphragm is obtained. The polyester microporous diaphragm of the present invention has good mechanical strength, thermal shrinkage and shutdown properties, can be used in the production and manufacture of secondary lithium batteries, and is especially suitable for secondary lithium batteries working at a temperature above 160°C.

Description

technical field [0001] The invention belongs to a diaphragm for lithium batteries and its preparation, and relates to a polyester microporous diaphragm for a secondary lithium battery and a preparation method thereof. The polyester microporous diaphragm of the invention is suitable for the production and manufacture of secondary lithium batteries, and is particularly suitable as the polyester microporous diaphragm for secondary lithium batteries working at a temperature above 160°C. Background technique [0002] In the prior art, the separator materials used in lithium batteries mainly include polypropylene, polyethylene, polyimide, and polyvinylidene fluoride, which are generally single-layer or multi-layer films, and the process methods mainly adopt dry method and Two types of wet methods. The shut-off temperature of single-layer or multi-layer separators of polypropylene and polyethylene materials using dry process is 130 ° C ~ 160 ° C, it is difficult to ensure the safe...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08L67/02C08L77/06C08L69/00C08L77/02C08L23/20C08L51/06C08K3/36B29C69/00B29C39/14B29C39/44B29C55/02H01M2/16H01M50/403H01M50/417H01M50/489
CPCY02E60/10
Inventor 赵贵红马雅琳胡俊祥罗春明李建学
Owner 四川东方绝缘材料股份有限公司
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