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Polyolefin microporous film and method for manufacturing same, separator for nonaqueous electrolyte secondary cell, and nonaqueous electrolyte secondary cell

A non-aqueous electrolyte and microporous membrane technology, which is applied in the field of polyolefin microporous membranes, can solve the problems of improving the pore size and making it difficult to take into account the shutdown characteristics, the safety cannot be obtained, and the pore size becomes larger, so as to suppress dendrites The generation and growth, strength and safety are excellent, and the effect of small pore size

Inactive Publication Date: 2017-05-10
TORAY IND INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since the pore blocking temperature is as high as 140°C and the time until membrane rupture is as short as 2 minutes (minutes), sufficient safety cannot be obtained.
[0012] In this way, for the microporous membrane obtained by the conventional stretching method, although the control of anisotropy is improved and the shrinkage temperature difference becomes larger, the pore diameter tends to become larger, and it is difficult to achieve both the improvement of the shutdown characteristic and the reduction of the pore diameter.

Method used

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  • Polyolefin microporous film and method for manufacturing same, separator for nonaqueous electrolyte secondary cell, and nonaqueous electrolyte secondary cell
  • Polyolefin microporous film and method for manufacturing same, separator for nonaqueous electrolyte secondary cell, and nonaqueous electrolyte secondary cell
  • Polyolefin microporous film and method for manufacturing same, separator for nonaqueous electrolyte secondary cell, and nonaqueous electrolyte secondary cell

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0134] PE1 (ultra-high molecular weight polyethylene, weight average molecular weight (Mw): 2.89×10 6 , molecular weight distribution (Mw / Mn): 5.28) 30% by weight and PE2 (high-density polyethylene, weight-average molecular weight: 5.72×10 5, Molecular weight distribution: 4.81) 70% by weight formed polyethylene composition. When the whole polyethylene composition was 100% by weight, the content of the polyethylene component with a molecular weight of 500,000 or less was 59% by weight, and the content of the polyethylene component with a molecular weight of 1,000,000 or more was 26% by weight. Add 71.5% by weight of liquid paraffin to 28.5% by weight of the polyethylene composition, further, based on the mass of polyethylene in the mixture, add 0.5% by mass of 2,6-di-tert-butyl-p-cresol and 0.7% by mass % tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate]methane was used as an antioxidant and mixed to prepare a polyethylene resin solution. This polyethylene...

Embodiment 2

[0136] A polyolefin microporous membrane was produced in the same manner as in Example 1 except that the draw ratio in the MD stretching step was 1.4 times. Tables 1 to 3 show the membrane properties of the obtained polyolefin microporous membrane.

Embodiment 3

[0138] A polyolefin microporous membrane was produced in the same manner as in Example 1 except that the draw ratio in the MD stretching step was 1.6 times. Tables 1 to 3 show the membrane properties of the obtained polyolefin microporous membrane.

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Abstract

Provided is a polyolefin microporous film having pores with small diameters and excellent shutdown characteristics, and which is suitable for a separator for a nonaqueous electrolyte secondary cell. The polyolefin microporous film is characterized in that the difference between the shutdown start temperature in the MD direction and the temperature at maximum shrinkage in the MD direction is 8.6 DEG C or greater, and the maximum pore diameter thereof is less than 0.036 [Mu]m. Also provided is a method for manufacturing the polyolefin microporous film, characterized by comprising melt-kneading and molding into a sheet shape a plasticizer and a polyolefin resin including an ultrahigh-molecular-weight polyolefin, stretching the resultant sheet in the MD direction and performing simultaneous biaxial stretching thereof, and then drying the stretched sheet.

Description

technical field [0001] The present invention relates to a polyolefin microporous film and a separator for a nonaqueous electrolyte secondary battery using the same, and relates to a polyolefin microporous film excellent in safety and a separator for a nonaqueous electrolyte secondary battery using the same diaphragm. Background technique [0002] For batteries that use non-aqueous electrolytes, such as lithium-ion batteries, a separator that has a shutdown function that shuts down the reaction when the temperature exceeds a predetermined temperature is required to prevent internal short circuits. Generally, battery separators are formed of microporous membranes, and when the temperature rises, they shrink near the melting point, and the microporosity closes, shutting down the battery reaction. In addition, when the temperature continues to rise further, the battery separator changes from contraction to elongation at a certain temperature, and eventually ruptures (melts). ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J9/26H01M2/16H01M10/0566H01M50/406H01M50/417H01M50/491H01M50/494
CPCC08J9/26H01M10/0566H01M2300/0017Y02E60/10H01M50/417H01M50/406H01M50/491H01M50/494B29C48/08B29C48/0018B29B7/88C08J5/2231C08J5/2275H01M50/581H01M50/403H01M10/0525Y02P70/50
Inventor 丰田直树菅田正美石原毅
Owner TORAY IND INC
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