Separator and method of preparing the same, and lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-10811658-B2
Application number	US-201314429619-A
Country	US
Kind code	B2
Filing date	Sep 17, 2013
Priority date	Sep 19, 2012
Publication date	Oct 20, 2020
Grant date	Oct 20, 2020

Abstract

An object of the present invention is to provide a separator maintaining high rate characteristics and enabling suppression of short circuit. The object is achieved by a separator comprising a substrate having an inner surface and an outer surface, and inorganic particles presented on the outer surface and the inner surface of the substrate, wherein the substrate has a porosity of 55% or more and a mean flow pore size of 30 μm or less, the inorganic particles have an average particle size of 1.0 to 4.0 μm, and the inorganic particles comprises 40% by volume or less of particles having a particle size of 1.0 μm or less and 30 to 75% by volume of particles having a particle size of 2.0 μm or more.

First claim

The invention claimed is:

1. A separator comprising a substrate having an inner surface and an outer surface, and inorganic particles present on the outer surface and the inner surface of the substrate,
wherein the substrate has a porosity of 55% or more and a mean flow pore size of 30 μm or less and comprises nonwoven fabric that has a coefficient of texture variation of 1.7 or less and a total basis weight of 5 to 15 g/m 2 ,
the inorganic particles have an average particle size of 1.0 to 4.0 μm, and the inorganic particles comprise 40% by volume or less of particles having a particle size of 1.0 μm or less and 30 to 75% by volume of particles having a particle size of 2.0 μm or more.

2. The separator according to claim 1 , wherein the substrate comprises a nonwoven fabric containing one or more resins selected from the group consisting of polyolefin-based resins and polyester-based resins.

3. The separator according to claim 2 , wherein the substrate comprises a laminated nonwoven fabric comprising a first nonwoven fabric layer comprising fibers having a fiber diameter of 4.0 μm or less and a second nonwoven fabric layer comprising fibers having a fiber diameter of more than 4.0 μm and 30.0 μm or less.

4. The separator according to claim 1 , further comprising 4 parts by mass or more of a binder based on 100 parts by mass of the inorganic particles, the binder being present inside the substrate.

5. A separator comprising a substrate having an inner surface and an outer surface, and inorganic particles present on the outer surface and the inner surface of the substrate,
wherein the substrate comprises a laminated nonwoven fabric formed by laminating a plurality of nonwoven fabric layers,
the laminated nonwoven fabric has a coefficient of texture variation of 1.7 or less and a total basis weight of 5 to 15 g/m 2 , and
the separator has a porosity of 45 to 70%,
a pore size distribution of the separator has one or more local maximum values in the range of a pore size of 0.1 to 1 μm and one or more local maximum values in the range of a pore size of 1 to 10 μm.

6. A method of preparing the separator according to claim 1 , the method comprising the steps of:
dispersing inorganic particles in a dispersive medium to prepare a slurry,
applying the slurry to a substrate or impregnating a substrate with the slurry to prepare a substrate with the slurry, and
drying the substrate with the slurry,
wherein the substrate has a porosity of 55% or more and a mean flow pore size of 30 μm or less,
the inorganic particles have the average particle size of 1.0 to 4.0 μm or less, and the inorganic particles comprise 40% by volume or less of particles having a particle size of 1.0 μm or less and 30 to 75% by volume of particles having a particle size of 2.0 μm or more.

7. The separator according to claim 1 , wherein the inorganic particles have a plate-like shape.

8. The separator according to claim 1 , wherein the separator is used for an electrochemical element.

9. A lithium ion secondary battery, comprising a positive electrode, a negative electrode, an electrolytic solution, and the separator according to claim 1 .

10. The lithium ion secondary battery according to claim 9 , wherein the electrolytic solution comprises at least one compound selected from the group consisting of carbonate esters having carbon-carbon double bond, cyclic carbonates having a fluorine atom, and sulfones.

11. The lithium ion secondary battery according to claim 10 , wherein the carbonate esters having carbon-carbon double bond comprise vinylene carbonate, the cyclic carbonates having a fluorine atom comprise fluoroethylene carbonate, and the sulfones comprise sulfolane.

12. The separator according to claim 1 , wherein the nonwoven fabric is a laminated nonwoven fabric comprising a nonwoven fabric layer (I) and a nonwoven fabric layer (II), wherein
the nonwoven fabric layer (I) contains 50% or more of microfibers having a fiber diameter from 0.3 μm to 4 μm, and
the nonwoven fabric layer (II) contains fibers having a fiber diameter of more than 4.0 μm and 30.0 μm or less.

Assignees

• Asahi Chemical Ind

Inventors

• Yamada Yusuke
• Uozumi Makoto
• Misao Takashi
• Nakamura Mitsutaka
• Sasayama Masaaki
• Kato Kazufumi

Classifications

• H01G11/52 Primary

  Separators · CPC title

• H01M50/457

  comprising three or more layers · CPC title

• H01M50/423

  Polyamide resins · CPC title

• H01M50/42

  Acrylic resins · CPC title

• H01M50/417

  Polyolefins · CPC title