Separator for lithium secondary battery and lithium secondary battery comprising same

Patent metadata

Field	Value
Publication number	US-2024291110-A1
Application number	US-202318574601-A
Country	US
Kind code	A1
Filing date	Feb 16, 2023
Priority date	Jun 3, 2022
Publication date	Aug 29, 2024
Grant date	—

Abstract

A lithium secondary battery separator having excellent heat resistance, adhesive strength, and insulation performance is provided. A lithium secondary battery separator according to one aspect of the present disclosure includes a porous polymer substrate, a first coating layer on a first surface of the porous polymer substrate, a second coating layer on a second surface of the porous polymer substrate, a first aqueous binder layer on a surface of the first coating layer, and a second aqueous binder layer on a surface of the second coating layer. The first coating layer and the second coating layer each include inorganic particles and a coating layer binder, in which the inorganic particles include aluminum nitride (AlN). The first aqueous binder layer and the second aqueous binder layer include different types of particle-type binders. The particle-type binder includes at least one selected from fluorine-containing binders and acrylic-containing binders.

First claim

1 . A separator for a lithium secondary battery, the separator comprising:
a porous polymer substrate; a first coating layer on a first surface of the porous polymer substrate; a second coating layer on a second surface of the porous polymer substrate; a first aqueous binder layer on a surface of the first coating layer; and a second aqueous binder layer on a surface of the second coating layer, wherein the first coating layer and the second coating layer each independently comprise inorganic particles and a coating layer binder, wherein the inorganic particles comprise aluminum nitride (AlN), wherein the first aqueous binder layer comprises a first particle-type binder and the second aqueous binder layer comprises a second particle-type binder, and wherein the first particle-type binder and the second particle-type binder are different from each other, and wherein the first particle-type binder and the second particle-type binder each independently comprise at least one of a fluorine-containing binder or an acrylic-containing binder.

2 . The separator of claim 1 , wherein the first particle-type binder and the second particle type particle-type binder each independently have an average particle diameter D 50 of 0.05 μm to 0.5 μm.

3 . The separator of claim 1 , wherein the fluorine-containing binder comprises at least one selected from group consisting of poly(vinylidenefluoride) (PVDF); and a copolymer of a vinylidenefluoride monomer and at least one selected from the group consisting of trifluoroethylene (TrFE), tetrafluoroethylene (TFF). hexafluoropropylene (HFP), trichloroethylene (TrCE). trichlorofluoroethylene (TCFE), chlorotrifluoroethylene (CTFE), polymethylmethacrylate (PMMA), and polyvinylacetate (PVAc).

4 . The separator of claim 1 , wherein the acrylic-containing binder comprises at least one of poly(methylmethacrylate), poly(ethylhexyl acrylate), poly(butylacrylate), poly(acrylonitrile), a copolymer of ethylhexyl acrylate and methyl methacrylate, a copolymer of butylacrylate and methyl methacrylate, an ethyl acrylate-acrylic acid-N,N-dimethylacrylamide copolymer, an ethyl acrylate-acrylic acid-2-(diethylamino)ethyl acrylate copolymer, an ethyl acrylate-acrylic acid-N,N-diethylacrylamide copolymer, or an ethyl acrylate-acrylic acid-2-(diethylamino)ethyl acrylate.

5 . The separator of claim 1 , wherein the coating layer binder comprises an aqueous particle-type binder, and
wherein the coating layer binder is the same as or different from the binder present in the first aqueous binder layer and the second aqueous binder layer.

6 . The separator of claim 1 , wherein the separator has a dry adhesive strength of 70 gf/25 mm or more with respect to an electrode.

7 . The separator of claim 1 , wherein the separator has a wet adhesive strength of 10 gf/25 mm or more with respect to an electrode.

8 . The separator of claim 1 , wherein an adhesive strength between the porous polymer substrate and at least one of the first coating layer and the second coating layer is 60 gf/15 mm or more.

9 . The separator of claim 1 , wherein the first coating layer and the second coating layer each independently have a thickness of 5 μm or less.

10 . The separator of claim 1 . wherein the first aqueous binder layer and the second aqueous binder layer each independently have a thickness of 2 μm or less.

11 . The separator of claim 1 , wherein the porous polymer substrate has a thickness of 15 μm or less.

12 . A lithium secondary battery, comprising:
an electrode assembly comprising a cathode, an anode, and a separator interposed between the cathode and the anode, wherein the separator is the separator claim 1 .

Assignees

• Lg Energy Solution Ltd

Inventors

• Lee So Yeong
• Kim Kyung Tae
• Park So Jung
• Bae Kyeong Hui
• Bae Won Sik
• Jeong So Mi

Classifications

• H01M50/434

  Ceramics · CPC title

• H01M50/451

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

• H01M50/42

  Acrylic resins · CPC title

• H01M50/443

  Particulate material · CPC title

• H01M50/446

  Composite material consisting of a mixture of organic and inorganic materials · CPC title