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Low-temperature-resistant lithium battery microporous membrane and preparation method thereof

A lithium battery and microporous membrane technology, which is applied in the field of low temperature resistant lithium battery microporous membrane and its preparation, can solve the problems of reducing diaphragm performance degradation, mechanical properties and puncture strength reduction, and achieves low closed cell temperature and high membrane rupture The effect of temperature

Active Publication Date: 2022-07-22
NINGBO CHANGYANG TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In order to overcome the problem that the mechanical properties and puncture strength of the dry uniaxially stretched lithium battery separator are reduced due to the brittle transition at low temperature, the present invention provides a low temperature resistant lithium battery microporous membrane and a preparation method thereof. Materials with a low glass transition temperature are added to the stretched diaphragm to effectively avoid the brittle transition of the diaphragm at low temperatures. The glass transition temperature of cis-1,4-polybutadiene is -100 °C, which has extremely high cold resistance , doped in polypropylene has good processing performance, which can reduce the performance decline of the diaphragm at low temperature; at the same time, the added inorganic whiskers can also enhance the mechanical properties of the diaphragm, and further ensure the strength of the diaphragm at low temperature

Method used

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  • Low-temperature-resistant lithium battery microporous membrane and preparation method thereof
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  • Low-temperature-resistant lithium battery microporous membrane and preparation method thereof

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preparation example Construction

[0032] The preparation method of the low temperature resistant lithium battery microporous film comprises the following steps:

[0033] (1) Cast sheet: Mix the components in the surface layer and the middle layer respectively and then perform three-layer co-extrusion, and the extrusion temperature is 190-210 °C; after pulling and cooling, the cast sheet is obtained, and the pulling speed is 20-50 m / min, the cooling temperature is 80-100 ℃;

[0034] (2) Stretch film formation: the obtained cast sheet is sequentially subjected to heat treatment, longitudinal cold stretching, longitudinal hot stretching, and heat setting treatment to obtain the low temperature resistant lithium battery microporous film, and the heat treatment temperature is 120-145 ℃ , the heat treatment time is 4-12 h; the longitudinal cold stretching temperature is 40-70 ℃, the stretching ratio is 1.2-1.5; the longitudinal hot stretching temperature is 120-140 ℃, the stretching ratio is 1.5-3.0; the heat setting...

Embodiment 1

[0036] A low temperature resistant lithium battery microporous film, such as figure 1 , figure 2 As shown, it consists of three layers: an upper surface layer 1, an intermediate layer 2 and a lower surface layer 1, the thickness of the single layer of the surface layer 1 is 10% of the microporous film of the low temperature resistant lithium battery, and the thickness of the intermediate layer 2 is 80% of the microporous film of low temperature lithium battery. In parts by mass, the surface layer 1 is 70 parts of high-density polyethylene and 30 parts of cis-1,4-polybutadiene, and the middle layer 2 is 79 parts of homopolypropylene, 20 parts of part of cis-1,4-polybutadiene and 1 part of calcium sulfate whiskers. The surface layer 1 has micropores 1 3 , and the intermediate layer 2 has micropores 2 4 and inorganic whiskers 5 .

[0037] The preparation method of the low temperature resistant lithium battery microporous film is:

[0038] (1) In parts by mass, 70 parts of hi...

Embodiment 2

[0047] The difference from Example 1 is that the surface layer is 50 parts of high-density polyethylene and 50 parts of cis-1,4-polybutadiene.

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Abstract

The invention relates to the field of battery multi-layer composite diaphragms, and provides a low-temperature-resistant lithium battery microporous membrane and a preparation method thereof in order to solve the problem that mechanical properties are reduced due to brittle transition of a dry-process uniaxial stretching lithium battery diaphragm at low temperature, the low-temperature-resistant lithium battery microporous membrane comprises a middle layer and surface layers arranged on the two sides of the middle layer, the raw materials of the surface layer comprise high-density polyethylene and cis-1, 4-polybutadiene, and the raw materials of the middle layer comprise homo-polypropylene, cis-1, 4-polybutadiene and inorganic whisker. According to the invention, the brittle transition of the diaphragm at low temperature is effectively avoided by adding a material with low glass transition temperature into the dry-process uniaxial tension diaphragm, cis-1, 4-polybutadiene is doped in polypropylene, so that the cis-1, 4-polybutadiene has good processability, and the performance degradation of the diaphragm at low temperature can be reduced; and the added inorganic whisker can enhance the mechanical properties of the diaphragm, and further ensure the strength of the diaphragm at low temperature.

Description

technical field [0001] The invention relates to the field of battery multilayer composite diaphragms, in particular to a low temperature resistant lithium battery microporous film and a preparation method thereof. Background technique [0002] The mainstream preparation methods of battery separators are dry uniaxially stretched separators, dry biaxially stretched separators and wet biaxially stretched separators. In the field of power vehicles, dry uniaxially stretched diaphragms and wet-coated biaxially stretched diaphragms are mainly used. Compared with wet coating separators, dry uniaxially stretched separators have lower cost and better long-term stability. With the popularization of blade batteries, the market demand for dry uniaxially stretched separators is also gradually increasing. improve. [0003] The main raw material of the dry uniaxially stretched diaphragm is polypropylene, which has high mechanical properties at room temperature. For example, patent CN1054...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M50/457H01M50/446H01M50/417H01M50/403H01M50/491
CPCH01M50/457H01M50/446H01M50/417H01M50/403H01M50/491Y02E60/10
Inventor 王绪田慧婷吴思瑶范建国孙卫健王晓钟
Owner NINGBO CHANGYANG TECH