Separator for lithium secondary battery, lithium secondary battery using the separator, and method of manufacturing the lithium secondary battery

Patent metadata

Field	Value
Publication number	US-10217985-B2
Application number	US-201514788509-A
Country	US
Kind code	B2
Filing date	Jun 30, 2015
Priority date	Aug 13, 2014
Publication date	Feb 26, 2019
Grant date	Feb 26, 2019

Abstract

A separator includes a porous base, and a first coating layer on a surface of the porous base, the first coating layer including a (meth)acrylic acid ester-based polymer having a glass transition temperature of about 10° C. to about 60° C. The first coating layer may be positioned opposite to a cathode of the lithium secondary battery. The separator may further include a second coating layer on a surface of the porous base opposite to the first coating layer and comprising a (meth)acrylic acid ester-based polymer.

First claim

What is claimed is:

1. A separator for a lithium secondary battery, the separator comprising:
a porous base, at least a portion of the porous base comprising at least one selected from polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyether sulfone, polyphenylene oxide, polyphenylene sulfide, polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, a polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene, and polypropylene; and
a first coating layer directly on a surface of the portion of the porous base and a second coating layer on a surface of the porous base opposite to the first coating layer, the first coating layer and the second coating layer each comprising a (meth)acrylic acid ester-based polymer having a glass transition temperature of about 10° C. to about 60° C.,
wherein the (meth)acrylic acid ester-based polymer is a polymerization product of an ethylenically unsaturated carboxylic acid ester and a monomer that is copolymerizable with the ethylenically unsaturated carboxylic acid ester,
wherein the ethylenically unsaturated carboxylic acid ester is a mixture of 2-ethylhexyl acrylate, isobornyl acrylate, and hydroxyethyl acrylate, or a mixture of methyl acrylate, ethyl acrylate, and hydroxyethyl acrylate, and
the monomer that is copolymerizable with the ethylenically unsaturated carboxylic acid ester is a mixture of acrylonitrile, methacrylic acid, acrylic acid, and ethylene dimethacrylate.

2. The separator of claim 1 , wherein the first coating layer is opposite to a cathode of the lithium secondary battery.

3. The separator of claim 1 , wherein the (meth)acrylic acid ester-based polymer has a glass transition temperature of about 20° C. to about 60° C.

4. The separator of claim 1 , wherein the first coating layer is a dot-patterned layer comprising a plurality of dots arranged at intervals.

5. The separator of claim 4 , wherein the plurality of dots have an average diameter of about 0.1 mm to about 1 mm and an average thickness of about 0.3 μm to about 10 μm, and at least one of the intervals between the dots is about 0.1 mm to about 10 mm.

6. The separator of claim 1 , wherein the second coating layer is a dot-patterned layer comprising a plurality of dots arranged at intervals.

7. The separator of claim 6 , wherein the plurality of dots have an average diameter of about 0.1 mm to about 1 mm and an average thickness of about 0.3 μm to about 10 μm, and at least one of the intervals between the dots is about 0.1 mm to about 10 mm.

8. The separator of claim 1 , further comprising an inorganic coating layer between the porous base and the second coating layer, the inorganic coating layer comprising inorganic particles of at least one selected from the group consisting of colloidal silica, α-alumina (α-Al 2 O 3 ), γ-alumina (γ-Al 2 O 3 ), boehmite (γ-AlO (OH)), gibbsite (γ-Al (OH) 3 ), zirconium oxide, magnesium fluoride, BaTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, ZnO, Y 2 O 3 , TiO 2 , SiC, and combinations thereof.

9. The separator of claim 1 , wherein the first coating layer and the second coating layer comprise the same (meth)acrylic acid ester-based polymer.

10. A lithium secondary battery comprising:
a cathode;
an anode; and
the separator of claim 1 between the cathode and the anode.

11. A method of manufacturing a lithium secondary battery, the method comprising:
forming a battery assembly comprising a cathode, an anode, and the separator of claim 1 , the separator comprising:
the porous base, at least a portion of the porous base comprising at least one selected from polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyether sulfone, polyphenylene oxide, polyphenylene sulfide, polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, a polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene, and polypropylene,
the first coating layer directly on the surface of the portion of the porous base and the second coating layer on the surface of the porous base opposite to the first coating layer, the first coating layer and the second coating layer each comprising the (meth)acrylic acid ester-based polymer having a glass transition temperature of about 10° C. to about 60° C.,
wherein the (meth)acrylic acid ester-based polymer is a polymerization product of an ethylenically unsaturated carboxylic acid ester and a monomer that is copolymerizable with the ethylenically unsaturated carboxylic acid ester,
wherein the ethylenically unsaturated carboxylic acid ester is a mixture of 2-ethylhexyl acrylate, isobornyl acrylate, and hydroxyethyl acrylate, or a mixture of methyl acrylate, ethyl acrylate, and hydroxyethyl acrylate, and
the monomer that is copolymerizable with the ethylenically unsaturated carboxylic acid ester is a mixture of acrylonitrile, methacrylic acid, acrylic acid, and ethylene dimethacrylate;
rolling up or stacking the battery assembly to obtain a rolled or stacked battery assembly, and heat-pressing the rolled or stacked battery assembly at a temperature of about 80° C. to about 120° C. to obtain a combined battery assembly; and
impregnating the combined battery assembly with an electrolyte.

12. The method of claim 11 , wherein the separator is obtained by coating an aqueous emulsion comprising the (meth)acrylic acid ester-based polymer on the two surfaces of the porous base and drying the coated (meth)acrylic acid ester-based polymer.

Assignees

• Samsung Sdi Co Ltd

Inventors

• Kim Ihn
• Kim Youngsu
• Jo Yunkyung
• Park Narae
• Moon Jungjin
• Min Seungjun
• Ko Sunggwi

Classifications

• H01M10/0525 Primary

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M50/443

  Particulate material · CPC title

• H01M50/457

  comprising three or more layers · CPC title

• H01M50/451

  comprising layers of only organic material and layers containing inorganic material · CPC title

• H01M50/42 Primary

  Acrylic resins · CPC title