Heat resisting micro pore film and battery diaphragm

A microporous film, heat-resistant technology, applied in the field of battery separators, can solve problems such as internal short circuits, achieve the effect of increasing the number and maintaining heat resistance

Active Publication Date: 2012-05-23
MURATA MFG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Shrinkage of the diaphragm causes secondary problems such as internal short circuits in some cases

Method used

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  • Heat resisting micro pore film and battery diaphragm
  • Heat resisting micro pore film and battery diaphragm
  • Heat resisting micro pore film and battery diaphragm

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0107] Polyvinylidene fluoride (PVdF) resin and N-methyl-2-pyrrolidone (NMP) each having a weight average molecular weight of 1,000,000 were mixed at a weight ratio of PVdF:NMP=10:90. Polyvinylidene fluoride was sufficiently dissolved in N-methyl-2-pyrrolidone, thereby preparing a polyvinylidene fluoride solution in which polyvinylidene fluoride was dissolved in an amount of 10% by weight.

[0108] A fine powder of alumina with an average particle size of 500 nm [Al 2 o 3 , Sumicorundum (registered trademark) AA-03, commercially available from Sumitomo Chemical Company, Limited] was added to the polyvinylidene fluoride solution as an inorganic material at 20 times the weight of polyvinylidene fluoride. The resultant was then stirred with a ball mill, thereby preparing a use slurry.

[0109] Next, the application slurry was applied to a substrate having a thickness of 12 μm as a polyethylene microporous membrane (commercially obtained from Tonen General Sekiyu K.K.) using a t...

Embodiment 2

[0115] The heat-resistant layers were individually formed on both faces of the substrate so that one heat-resistant layer had a thickness of 1.55 μm and the total heat-resistant layers had a thickness of 3.1 μm. A microporous membrane with a heat-resistant layer was produced in the same manner as employed in Example 1 except for such a process configuration.

[0116] In the microporous membrane produced in this way, the total thickness of the heat-resistant layer was 6.2 times the average particle diameter of the heat-resistant particles contained in the heat-resistant layer. In addition, in the surface of the heat-resistant layer, it was found that the number of protrusions was 20.7 and the area was 46.1 μm 2 .

Embodiment 3

[0118] The heat-resistant layers were individually formed on both faces of the substrate so that the thickness of one heat-resistant layer was 2.75 μm and the total thickness of the heat-resistant layers was 5.5 μm. A microporous membrane with a heat-resistant layer was produced in the same manner as employed in Example 1 except for such a process configuration.

[0119] In the microporous membrane produced in this way, the total thickness of the heat-resistant layer was 11.0 times the average particle diameter of the heat-resistant particles contained in the heat-resistant layer. In addition, in the surface of the heat-resistant layer, it was found that the number of protrusions was 1.4 and the area was 1.0 μm 2 .

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Abstract

The invention relates to a heat resisting micro pore film and a battery diaphragm. The heat resisting micro pore film and the battery diaphragm respectively include substrates formed by utilizing porous membranes and heat resisting layers including heat resisting resin and heat resisting particles formed on at least one surfaces of the substrates. Less than 60 projections per 0.0418 mm2 are formed on the surface of the heat resisting layer. The projections are perpendicular to the heat resisting layer and have an area of less than 500 micro mm2 per 0.0418 mm2. The projections are formed by the gathering of the heat resisting particles and are a highly average face relatively to the heat resisting layer. The projections have a height of at least double of the average particle diameter of the heat resisting diameter. The invention provides the heat resisting micro pore film and the battery diaphragm. In the invention, without increasing the thickness of the surface layer, the heat retraction can be inhibited.

Description

technical field [0001] The present invention relates to a heat-resistant microporous film (heat-resistant microporous film) having a heat-resistant insulating layer (heat-resistant insulating layer), more particularly relates to each having a substrate (substrate) and a heat-resistant layer (heat-resistant layer) ), the substrate is made by using a polyolefin resin, and the heat-resistant layer has a structure in which inorganic particles are contained in the heat-resistant resin. Background technique [0002] In recent years, portable electronic information devices such as mobile phones, camcorders, and notebook computers have been widely used, and thus such devices have been developed to have enhanced performance, reduced size, and reduced weight. These devices each have a power source such as a disposable primary battery or a secondary battery capable of repeated use. Demand for secondary batteries, especially lithium ion secondary batteries, is increasing in terms of ov...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/14H01M2/16H01M50/403H01M50/451H01M50/457H01M50/463H01M50/489H01M50/491
CPCY02E60/12H01M2/1686H01M2/18H01M10/4235H01M2/14H01M10/052H01M2/145H01M2/16H01M2/166H01M50/446H01M50/403H01M50/463H01M50/451H01M50/491H01M50/489H01M50/457Y10T428/24372Y02E60/10H01M10/0525H01M2220/30
Inventor 柿部亚希子李成吉冈本和广
Owner MURATA MFG CO LTD
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