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Polyolefin microporous membrane

A technology made of microporous membranes and polyolefins, which is applied in the direction of separators/films/diaphragms/spacers, structural parts, battery pack components, etc. Reduced battery capacity, internal short-circuit failure, etc., to achieve good cycle characteristics, improved mechanical properties, and good oxidation resistance

Active Publication Date: 2009-09-16
ASAHI KASEI KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] However, when the microporous membrane described in these documents is used as a separator of a lithium ion battery, there is a problem that the battery capacity decreases or an internal short circuit failure occurs.
[0009] Thus, when used as a battery separator, especially when used as a battery separator using an alloy-based negative electrode, it is impossible to obtain a polyolefin microporous membrane that achieves good battery characteristics.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0171] 95 wt% of polyethylene having a Mv of 250,000 as a homopolymer and 5 wt% of polypropylene having a homopolymer of Mv of 400,000 were dry mixed using a drum mixer. Add 1wt% pentaerythritol-tetrakis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl]propionate) as an antioxidant in 99wt% of the resulting pure polymer mixture, again using drum mixing machine for dry mixing to obtain a mixture of polymers and the like. After substituting the mixture of the obtained polymer and the like under nitrogen, it was supplied to a twin-screw extruder by a feeder under a nitrogen atmosphere. Liquid paraffin (dynamic viscosity at 37.78°C is 7.59×10 -5 m 2 / s) Use a booster pump to inject into the barrel of the extruder. In addition, the melting point which is the first peak of the pure polymer mixture obtained by the DSC method at 10°C / min was 137.2°C.

[0172] The feeder and pump were adjusted so that the liquid paraffin accounted for 55 wt% of the total mixture that was melted, kneaded, and ...

Embodiment 2

[0180] Dry mixing of 47.5 wt% polyethylene with a Mv of 700,000 homopolymer, 47.5 wt% polyethylene with a homopolymer of Mv of 250,000, 5 wt% of a homopolymer with a Mv of 400,000 material polypropylene. In 99wt% of the obtained pure polymer mixture, add 1wt% pentaerythritol-tetrakis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl] propionate) as an antioxidant, again using a drum The mixer performs dry mixing to obtain mixtures such as polymers. After substituting the mixture of the obtained polymer and the like under nitrogen, it was supplied to a twin-screw extruder by a feeder under a nitrogen atmosphere. Liquid paraffin (dynamic viscosity at 37.78°C is 7.59×10 -5 m 2 / s) Use a booster pump to inject into the barrel of the extruder.

[0181] Adjust the feeder and the pump so that the amount of liquid paraffin in the total mixture of melting, kneading and extruding reaches 65wt%. Melting and kneading conditions were performed at a set temperature of 200° C., a screw rotation spe...

Embodiment 3

[0189] The same procedure as in Example 2 was performed except that after extrusion onto a cooling roll, casting was performed by build-up molding, and embossing was performed under the following conditions, biaxial stretching temperature 118°C, and heat setting temperature 122°C.

[0190] The embossing in this example was carried out by passing the gel sheet between two embossing rolls (roll 1, roll 2) so that the linear pressure between the two rolls was 110 N / mm. The outer diameters of rolls 1 and 2 are both Φ100 mm, the embossed pattern is oblique grid, the mesh size is 64 per inch, the depth is 0.102 mm, and the surface temperature is controlled at 85°C.

[0191] For the obtained polyolefin microporous membrane, the results of evaluating various physical properties, battery performance, and electrolyte solution retention state are shown in Table 1, and the results of observing the shape of the protrusions are shown in Table 1. figure 1 .

[0192] It should be noted that...

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Abstract

A polyolefin microporous membrane, which has a thickness of 1-100[mu]m, a pore diameter of 0.01-1[mu]m and a protrusion having a height of 0.5-30[mu]m arranged by embossing at least on one surface, is provided. A method for manufacturing the membrane and a battery separator made of the membrane are also provided.

Description

technical field [0001] The present invention relates to microporous membranes widely used as separation membranes for material separation, selective permeation, etc., and separators for electrochemical reaction devices such as alkalis, lithium-ion batteries, fuel cells, and capacitors, and in particular, as non-aqueous electrolyte batteries. A microporous membrane made of polyolefin is preferably used as the separator. Background technique [0002] Microporous membranes made of polyolefins are widely used as separation membranes or selective permeation separation membranes and separators for various substances. Examples of applications include microfiltration membranes, diaphragms for fuel cells and capacitors, or filling pores with functional materials. Masterbatches for functional films expressing new functions, separators for batteries, etc. Among them, separators for lithium ion batteries are particularly preferably used as one of non-aqueous electrolyte batteries widel...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J9/00H01M2/16H01M2/18H01M10/0565H01M50/417H01M50/463H01M50/489H01M50/491H01M50/494
CPCY02E60/12H01M10/0565H01M2/18H01M2/1653H01M2300/0082Y02E60/10H01M50/463H01M50/417H01M50/491H01M50/494H01M50/489C08J9/22C08J5/22H01M10/052H01M50/411H01M50/406
Inventor 酒向谦太朗西村佳史
Owner ASAHI KASEI KK
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