Slurry for forming insulating layer, separator for electrochemical device, method for producing the same, and electrochemical device

Inactive Publication Date: 2010-09-02
HITACHT MAXELL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0020]The slurry for forming an insulating layer of the present invention is capable of achieving the uniform dispersion of the insulating fine particles and maintaining the dispersion state stably. The separator for an electrochemical device of the present invention is produced using the slurry for forming an insulating layer of the present invention and

Problems solved by technology

Thus, it is hard to say that the margin for safety of the battery is sufficient.
Moreover, the film has been distorted by drawing and may shrink due to residual stress when it is subjected to high temperatures.
If the pores are not sufficiently closed and the current cannot be immediately reduced, the temperature of the battery is easily raised to the shrinkage temperature of the separator, so that an internal short circuit can occur.
Thus, it may be difficult to maintain a stable dispersion state of the fine particles in the slurry.
When the slurry in which the fine particles are agglomerated or settled is applied to the base or the like, the application tends to be not uniform.
Moreover, when the dispersi

Method used

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  • Slurry for forming insulating layer, separator for electrochemical device, method for producing the same, and electrochemical device

Examples

Experimental program
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Effect test

Example

Example 1

[0133]To 1000 g of plate-like boehmite (insulating fine particles) with an aspect ratio of 10 were added 1000 g of water (dispersion medium) and 1 part by mass of ammonium polyacrylate (dispersing agent) with respect to 100 parts by mass of boehmite, and then mixed in a bench ball mill for 6 days, so that the plate-like boehmite was dispersed in water. It was confirmed that d10, d30, d50, and d90 of the boehmite in the resultant dispersion were 0.40 μm, 0.68 μm, 0.98 μm, and 1.86 μm, respectively, that the average particle size was 0.98 μm, and that the proportion of particles with a particle size of 1 μm or less was 50 vol % or more and the proportion of particles with a particle size of 3 μm or more was 10 vol % or less.

[0134]Next, an emulsion of a self-crosslinking acrylic acid copolymer including butyl acrylate as the main component of the monomer was used as a binder, and 3 parts by mass of the emulsion with respect to 100 parts by mass of boehmite was added to the dis...

Example

Example 2

[0137]A slurry for forming an insulating layer was produced in the same manner as Example 1 except that polyhedral alumina was used instead of the plate-like boehmite. It was confirmed that d10, d30, d50, and d90 of the alumina dispersed in water were 0.40 μm, 0.47 μm, 0.54 μm, and 1.15 μm, respectively, that the average particle size was 0.54 μm, and that the proportion of particles with a particle size of 1 μm or less was 50 vol % or more and the proportion of particles with a particle size of 3 μm or more was 10 vol % or less. As a result of the measurement of the slurry thus obtained in the same manner as Example 1, the viscosity was 180 mPa·s and the height of sedimentation after one week was 53 mm.

Example

Example 3

[0138]A slurry for forming an insulating layer was produced in the same manner as Example 1 except that plate-like alumina with an aspect ratio of 25 was used instead of the plate-like boehmite. It was confirmed that d10, d30, d50, and d90 of the alumina dispersed in water were 0.43 μm, 0.78 μm, 1.05 μm, and 1.20 μm, respectively, that the average particle size was 1.05 μm, and that the proportion of particles with a particle size of 1 μm or less was 30 vol % or more and the proportion of particles with a particle size of 3 μm or more was 10 vol % or less. As a result of the measurement of the slurry thus obtained in the same manner as Example 1, the viscosity was 190 mPa·s and the height of sedimentation after one week was 55 mm.

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Abstract

A slurry for forming an insulating layer of the present invention includes heat-resistant insulating fine particles, a thickening agent, and a dispersion medium. The insulating fine particles are dispersed in the dispersion medium. The slurry for forming an insulating layer has a viscosity of 5 to 500 mPa·s. The proportion of particles with a particle size of 1 μm or less in the insulating fine particles is 30 vol % or more and the proportion of particles with a particles size of 3 μm or more in the insulating fine particles is 10 vol % or less. An electrochemical device of the present invention includes a separator for an electrochemical device of the present invention that is produced using the slurry for forming an electrochemical device of the present invention.

Description

TECHNICAL FIELD[0001]The present invention relates to a slurry for forming an insulating layer suitable for the constituent of a separator for an electrochemical device, a separator for an electrochemical device having an insulating layer formed of the slurry and a method for producing the separator, and an electrochemical device including the separator.BACKGROUND ART[0002]A lithium secondary battery, which is a type of an electrochemical device, is characterized by a high energy density and thus has been widely used as a power source for portable equipment such as a portable telephone and a notebook personal computer. The capacity of the lithium secondary battery is likely to increase further as the performance of the portable equipment becomes higher. For this reason, it is important to ensure the safety of the lithium secondary battery.[0003]In the current lithium secondary battery, e.g., a polyolefin microporous film (microporous film) with a thickness of about 20 to 30 μm is us...

Claims

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Application Information

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IPC IPC(8): B32B3/26C08L5/00B32B5/16B05D5/12H01M10/058H01M10/38H01M50/403H01M50/449
CPCH01G9/02H01G9/155H01M2/166Y10T428/25H01M10/058Y02E60/13Y02T10/7022H01M2/1673Y10T428/249991Y10T442/20Y02T10/70Y02E60/10H01M50/446H01M50/46Y02P70/50H01G11/52H01M50/449H01M50/403
Inventor KATAYAMA, HIDEAKIABE, HIROSHIMATSUMOTO, NOBUAKIABE, TOSHIHIROKUROKI, YASUTAKA
Owner HITACHT MAXELL LTD
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