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Lithium battery separator with thermal switch function and preparation method of lithium battery separator

A lithium battery diaphragm and thermal switch technology, which is applied to battery pack components, separators/films/diaphragms/spacers, circuits, etc., can solve problems affecting lithium battery capacity, low diaphragm safety, and difficult recovery of micropores, etc. problems, to achieve the effect of low cost, excellent safety performance and high efficiency

Active Publication Date: 2016-08-10
CHENGDU WISEDONE TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In order to solve the problem that the lithium battery diaphragm prepared by the prior art is low in safety, and the micropores are difficult to recover after being closed at high temperature, which affects the capacity of the lithium battery, the purpose of the present invention is to provide a more excellent safety performance with a thermal switch function. Lithium battery diaphragm and preparation method thereof

Method used

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  • Lithium battery separator with thermal switch function and preparation method of lithium battery separator
  • Lithium battery separator with thermal switch function and preparation method of lithium battery separator
  • Lithium battery separator with thermal switch function and preparation method of lithium battery separator

Examples

Experimental program
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Effect test

Embodiment 1

[0035] The matrix resin is homopolypropylene T38F produced by Lanzhou Petrochemical (melting index: 3.0g / 10min; melting point: 165°C) and 10wt% of temperature-sensitive polymer additive hydrogenated styrene-butadiene-styrene block copolymer Melt compounding in a twin-screw extruder. The melt is extruded through a slit-shaped die and cooled by a chilled roll to obtain a polypropylene base film. The temperature of the chilled roll is 80° C., and the cooled polypropylene base film is folded flat by a traction roll. The polypropylene base film was first stretched longitudinally along the extrusion direction at a stretching temperature of 70°C and a stretching ratio of 2.0; then transversely stretched at a stretching temperature of 90°C and a stretching ratio of 2.0.

[0036] The results of scanning electron microscopy of the section of the polypropylene base film prepared by this method are as follows: figure 1 As shown in a, it can be seen that the added thermosensitive polymer ...

Embodiment 2

[0039] The matrix resin is homopolypropylene T30S (melt index: 3.5g / 10min; melting point: 167°C) produced by Daqing Petrochemical Co., Ltd. and 15wt% temperature-sensitive polymer additive ethylene ethyl acrylate, which is melt-mixed in a twin-screw extruder. The melt is extruded through a slit-shaped die and cooled by a chilled roll to obtain a polypropylene base film. The temperature of the chilled roll is 70° C., and the cooled polypropylene base film is folded flat by a traction roll. The polypropylene base film was first stretched longitudinally along the extrusion direction at a stretching temperature of 80°C and a stretching ratio of 2.5; then transversely stretched at a stretching temperature of 100°C and a stretching ratio of 2.5.

[0040] The lithium battery diaphragm prepared by the method has excellent pore size distribution uniformity, a porosity of 46%, and a Gurley value of 262s / 100cc. After the diaphragm is placed in an oven at 130°C for 30 minutes, the shrinka...

Embodiment 3

[0042] The matrix resin is homopolypropylene F401 produced by Yangzi Petrochemical (melting index: 1.8g / 10min; melting point: 166°C) and 20wt% temperature-sensitive polymer additive EPDM rubber, which is melt-mixed in a twin-screw extruder . The melt is extruded through a slit-shaped die and cooled by a chilled roll to obtain a polypropylene base film. The temperature of the chilled roll is 60° C., and the cooled polypropylene base film is folded flat by a traction roll. The polypropylene base film was first stretched longitudinally along the extrusion direction at a stretching temperature of 90°C and a stretching ratio of 3.0; then transversely stretched at a stretching temperature of 110°C and a stretching ratio of 3.0.

[0043] The lithium battery diaphragm prepared by the method has excellent pore size distribution uniformity, a porosity of 49%, and a Gurley value of 250s / 100cc. After the diaphragm is placed in an oven at 130°C for 30 minutes, the shrinkage rate of the di...

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Abstract

The invention discloses a lithium battery separator with a thermal switch function and a preparation method of the lithium battery separator. The lithium battery separator is prepared from the following raw materials in percentage by mass: 60%-90% of homopolypropylene and 10%-40% of a thermosensitive polymer additive, wherein the melting point of the homopolypropylene is 160-170 DEG C; and the thermosensitive polymer additive has a significant thermal expansion effect within a temperature range of 100-140 DEG C. The preparation method comprises the following steps: preparing a polypropylene base membrane through a flow-casting strip and preparing a microporous membrane through step-by-step two-way stretching to prepare the lithium battery separator with the thermal switch function. The prepared lithium battery separator is high in porosity and excellent in pore size distribution uniformity, and has excellent safety performance; the pore closing temperature is about 100-140 DEG C; the film breaking temperature is about 165 DEG C; meanwhile, when the separator is cooled to a room temperature, the closed micropores are opened again; the capacity and the service lifetime of the lithium battery are not affected; and the lithium battery separator can be applied to the field of mobile phone batteries, electric vehicle batteries and the like.

Description

technical field [0001] The invention relates to the technical field of battery diaphragm preparation, and more specifically relates to a lithium battery diaphragm with a thermal switch function and a preparation method thereof. Background technique [0002] Rechargeable lithium-ion secondary batteries have the characteristics of long cycle life, high specific energy, no memory effect, fast charging and discharging, and safety and reliability. They have become a research hotspot of new power supply technology in recent years and have been widely used Used in mobile phone batteries, laptop batteries, and electric vehicle batteries. Lithium battery cells are mainly composed of negative electrode materials, positive electrode materials, diaphragms and electrolytes. The porous diaphragm is an important part of the cell. The main function of the diaphragm is to separate the positive and negative electrodes of the battery to prevent short-circuiting between the two electrodes. In ...

Claims

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Application Information

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IPC IPC(8): H01M2/14H01M2/16H01M50/403H01M50/411
CPCH01M50/40H01M50/403H01M50/409Y02E60/10
Inventor 吴桐惠志锋
Owner CHENGDU WISEDONE TECH
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