Microporous polyolefin membrane, separator for secondary batteries, and secondary battery

A technology of microporous membrane and secondary battery, applied in battery pack parts, separators/films/diaphragms/spacer elements, membranes, etc., can solve problems such as reduced thermal stability of electrodes

Pending Publication Date: 2021-11-05
TORAY IND INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In recent years, the high density of energy density in secondary batteries has progressed, and the thermal stability o

Method used

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  • Microporous polyolefin membrane, separator for secondary batteries, and secondary battery
  • Microporous polyolefin membrane, separator for secondary batteries, and secondary battery

Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0168] (Example 1)

[0169] The weight average molecular weight (Mw) of 1.5 × 10 6 Mp 127 ℃ ultrahigh molecular weight polyethylene and 40% by mass weight-average molecular weight (Mw) of 3.0 × 10 5 , High-density branched polyethylene melting point 133 ℃ mixing 60% by mass, it is set to a polyolefin mixture A. By the above-mentioned polyolefin mixture and 24.8% by mass as an antioxidant, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) - propionate] methane, 0.2% by mass obtained by mixing substance into the twin screw extruder, a biaxial extruder from the side feeder feed liquid paraffin 75% by mass of the machine, and at 200 ℃ 250rpm, Q / Ns = 0.2 melt-kneaded under the conditions, to prepare a polyolefin resin composition A. A polyolefin resin composition was fed to a T-die, extruded as a sheet, a cooling roll adjusted to a temperature of 30 deg.] C while pulling speed at 4m / min traction while cooling, a gel-like sheet formed.

[0170] The resulting gel-like sheet so ...

Example Embodiment

[0171] (Example 2)

[0172] The weight average molecular weight (Mw) of 1.5 × 10 6 , 127 deg.] C melting point of ultrahigh molecular weight polyethylene 15% by mass, weight average molecular weight (Mw) of 3.0 × 10 5 , High density polyethylene, m.p. 85 deg.] C to 133 mass% branched mixed, to which a mixture of polyolefin A, except that, in Example 1 in the same manner to obtain a polyolefin microporous membrane.

Example Embodiment

[0173] (Example 3)

[0174] The resulting gel-like sheet so as to be a quadrangular manner 80mm square was cut out, so as to be in the MD direction at a stretching temperature 110 ℃, a tensile speed of 1000mm / min 7 times, becomes 7 times in the TD direction manner simultaneous biaxial stretching carried out, except that in Example 1 to obtain the same manner as the polyolefin microporous membrane.

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Abstract

The present invention addresses the problem of providing a microporous polyolefin membrane which has not only a low shutdown temperature but also an excellent membrane strength at the shutdown temperature, and imparts excellent shutdown characteristics and high safety if used as a separator for secondary batteries. The present invention provides, as a solution, the microporous polyolefin membrane which has a shutdown temperature of 135 DEG C or less, while having a crystal melting rate of 50% or less at the shutdown temperature.

Description

technical field [0001] The present invention relates to a polyolefin microporous membrane having excellent shutdown characteristics and high safety when used as a separator for a secondary battery, a separator for a secondary battery comprising the polyolefin microporous membrane, and a secondary battery. Background technique [0002] Microporous membranes are used in various fields such as filters such as filtration membranes and dialysis membranes, separators for secondary batteries, and separators for electrolytic capacitors. Among them, polyolefin microporous membranes using polyolefin as a resin material have been widely used as separators for secondary batteries in recent years because they are excellent in chemical resistance, insulation, mechanical strength, etc., and have shutdown characteristics. [0003] Secondary batteries, such as lithium ion secondary batteries, are widely used as batteries for personal computers, mobile phones, and the like due to their high e...

Claims

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Application Information

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IPC IPC(8): H01M50/417H01M50/491H01M50/489H01M50/449H01M50/457H01M50/409
CPCY02E60/10H01M50/409H01M50/491H01M50/489H01M50/417H01M50/449B01D71/26B01D69/12B01D2325/22H01M50/581H01M10/0525
Inventor 西村直哉下川床辽久万琢也
Owner TORAY IND INC
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