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Battery separator and method for producing same

A diaphragm and battery technology, applied in the field of battery diaphragm and its manufacturing, can solve the problems of membrane closure characteristics and airtightness deterioration, difficulty in ensuring safety, airtightness deterioration, etc., and achieve the effect of excellent closure characteristics

Active Publication Date: 2015-03-18
TORAY IND INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there is a problem that the resin component permeates into the pores of the polyolefin microporous membrane, resulting in deterioration of the membrane's shut-off characteristics and air-tightness.
In addition, sometimes the resin component forms a thin film on the surface of the polyolefin microporous membrane, further deteriorating the airtightness
In addition, in the process of laminating the modified porous layer on the polyolefin microporous membrane, the slitting process, or the battery assembly process, the modified porous layer may peel off, and in such a case, there is also a problem that it is difficult to ensure safety.

Method used

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  • Battery separator and method for producing same
  • Battery separator and method for producing same
  • Battery separator and method for producing same

Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0069] (1) Preparation process of polyolefin resin solution

[0070] The polyolefin resin solution is prepared by adding a suitable film-forming solvent to the above-mentioned polyolefin resin, followed by melt-kneading. Various additives such as the above-mentioned inorganic fillers, antioxidants, ultraviolet absorbers, antiblocking agents, pigments, and dyes can be added to the polyolefin resin solution as needed within a range that does not impair the effects of the present invention. For example, micronized silicic acid can be added as a pore former.

[0071] As the film-forming solvent, any of liquid solvents and solid solvents can be used. Examples of the liquid solvent include aliphatic or cyclic hydrocarbons such as nonane, decane, decalin, p-xylene, undecane, dodecane, and liquid paraffin, and mineral oil fractions having boiling points corresponding to them. In order to obtain a gel-like sheet with a stable solvent content, it is preferable to use a non-volatile li...

Embodiment 1

[0193]

[0194] In 100 parts by mass, the mass average molecular weight (Mw) of 30 mass% is 2.5×10 6 The Mw of ultra-high molecular weight polyethylene (UHMWPE) and 70% by mass is 2.8×10 5 Dry mixing of 0.375 parts by mass of tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)- propionate] methane to give a mixture.

[0195] Mw of UHMWPE and HDPE was determined by gel permeation chromatography (GPC) under the following conditions (the same applies hereinafter).

[0196] ・Measuring device: GPC-150C manufactured by Waters Corporation

[0197] ・Column: Showa Denko Co., Ltd. "Shodex" (registered trademark) UT806M

[0198] ·Column temperature: 135℃

[0199] Solvent (mobile phase): o-dichlorobenzene

[0200] ·Solvent flow rate: 1.0mL / min

[0201] ・Sample concentration: 0.1% by mass (dissolution condition: 135°C / 1h)

[0202] ·Loading volume: 500μL

[0203] Detector: Differential refractometer manufactured by Waters Corporation

[0204] • Calibration curve: Prepared wi...

Embodiment 2

[0212]

[0213] As in Example 1, a polyolefin microporous membrane (a) was used.

[0214]

[0215]50.0 mass parts of solvents were added to 1.0 mass parts of CMC product number 2200 (made by Daicel FineChem Co., Ltd.), and it stirred for 2 hours. Next, add 49.0 parts by mass of nearly spherical alumina particles with an average particle diameter of 0.5 μm, stir for 2 hours to fully disperse the alumina particles, and then use polypropylene felt with a filter particle size (initial filtration efficiency: 95%) of 10 μm Finely filtered with a type filter to prepare a coating solution (B). At this time, the volume ratio of the resin component and the fine particles was 5:95.

[0216]

[0217] The polyolefin microporous membrane (a) was coated with the coating solution (B) in the same manner as in Example 1, and dried to obtain a battery separator.

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Abstract

A battery separator which is a laminated polyolefin microporous membrane, comprising a polyolefin microporous membrane, and a modifying porous layer comprising a water-soluble resin or water-dispersible resin, and fine particles, the modifying porous layer being laminated on at least one surface of the polyolefin microporous membrane, wherein the polyolefin microporous membrane comprises a polyethylene resin and has (a) a shutdown temperature (a temperature at which an air resistance measured while heating the polyolefin microporous membrane at a temperature rise rate of 5°C / min reaches 1 × 10 5 sec / 100 cc) of 135°C or lower, (b) a rate of air resistance change (a gradient of a curve representing dependency of the air resistance on temperature at an air resistance of 1 × 10 4 sec / 100 cc) of 1 × 10 4 sec / 100 cc / °C or more, (c) a transverse shrinkage rate at 130°C (measured by thermomechanical analysis under a load of 2 gf at a temperature rise rate of 5°C / min) of 20% or less, and a thickness of 16 µm or less, the shutdown temperature difference between the polyolefin microporous membrane and the laminated polyolefin microporous membrane being 4.0°C or less. A method of producing the same. Provided is a battery separator with excellent adhesion and shutdown properties comprising a modifying porous layer and a polyolefin microporous membrane.

Description

technical field [0001] The present invention relates to a battery separator using a laminated polyolefin microporous membrane and a method for producing the same. Background technique [0002] Non-aqueous electrolyte batteries represented by lithium-ion secondary batteries have high energy density and are widely used as power sources for notebook computers, mobile phones, electric vehicles, and the like. [0003] In the non-aqueous electrolyte battery with high energy density, abnormal heat generation is likely to occur when an internal short circuit occurs, and therefore, a function of preventing the temperature from rising above a predetermined temperature is required. In response to this, a method of ensuring safety is adopted by using a microporous membrane mainly composed of polyolefin as a separator. The polyolefin microporous membrane has shutdown characteristics in which the resin melts at about 130°C, clogging the pores and blocking the flow of ions, so it can supp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/16H01M2/14H01M50/406H01M50/414H01M50/431H01M50/449H01M50/489
CPCH01M2/1686H01M2/1653H01M2/166H01M50/446H01M50/449H01M50/431H01M50/489H01M50/414H01M50/406H01M2220/20H01M2220/30Y02E60/10H01M50/417H01M50/443H01M50/581H01M50/403Y02P70/50H01M50/44H01M10/0525
Inventor 水野直树君岛康太郎
Owner TORAY IND INC
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