Separator for lithium secondary battery and lithium secondary battery including the same

Patent metadata

Field	Value
Publication number	US-12512557-B2
Application number	US-202117923145-A
Country	US
Kind code	B2
Filing date	Oct 21, 2021
Priority date	Oct 21, 2020
Publication date	Dec 30, 2025
Grant date	Dec 30, 2025

Abstract

A separator for a lithium secondary battery and a lithium secondary battery including the separator, including a porous polymer substrate; and a porous coating layer on at least one surface of the porous polymer substrate. The porous coating layer includes first inorganic particles surface-treated with a polyphenol-containing compound, second inorganic particles surface-treated with an organic acid, and a binder polymer. The first inorganic particles have an average particle diameter of 100 nm to 700 nm, and the second inorganic particles have an average particle diameter of 30 nm to 80 nm. The separator for a lithium secondary battery uses two types of surface-treated inorganic particles having a different average particle diameter. Therefore, the inorganic particles have improved dispersibility, and the separator has high thermal safety and can prevent separation of the inorganic particles.

First claim

What is claimed is:

1 . A separator for a lithium secondary battery, comprising:
a porous polymer substrate; and a porous coating layer on at least one surface of the porous polymer substrate, wherein the porous coating layer comprises first inorganic particles surface-treated with a polyphenol-containing compound, second inorganic particles surface-treated with an organic acid, and a binder polymer, wherein the first inorganic particles have an average particle diameter of 100 nm to 700 nm, and wherein the second inorganic particles have an average particle diameter of 30 nm to 80 nm.

2 . The separator for the lithium secondary battery according to claim 1 , wherein the average particle diameter of the first inorganic particles ranges from 400 nm to 600 nm.

3 . The separator for the lithium secondary battery according to claim 1 , wherein the average particle diameter of the second inorganic particles ranges from 30 nm to 45 nm.

4 . The separator for the lithium secondary battery according to claim 1 , wherein the second inorganic particles have a zeta (ζ) potential of −20 mV or less.

5 . The separator for the lithium secondary battery according to claim 4 , wherein the zeta potential of the second inorganic particles is as measured under an aqueous condition.

6 . The separator for the lithium secondary battery according to claim 1 , wherein the polyphenol-containing compound comprises at least one of tannic acid, polydopamine, catechin, resveratrol, quercetin, flavonoid, isoflavone, catechol, hydroquinone, or resorcin.

7 . The separator for the lithium secondary battery according to claim 1 , wherein the organic acid comprises at least one of sulfonic acid, or carboxylic acid.

8 . The separator for the lithium secondary battery according to claim 7 , wherein the sulfonic acid comprises at least one of benzenesulfonic acid, or para-toluenesulfonic acid.

9 . The separator for the lithium secondary battery according to claim 7 , wherein the carboxylic acid comprises at least one of acetic acid, propanoic acid, butyric acid, palmitic acid, lactic acid, tartaric acid, malic acid, glycolic acid, maleic acid, phthalic acid, succinic acid, arginine, glycine, glucuronic acid, gluconic acid, or citric acid.

10 . The separator for the lithium secondary battery according to claim 1 , wherein the first inorganic particles comprise at least one of BaTiO 3 , BaSO 4 , Pb(Zr,Ti)O 3 (PZT), Pb 1-x La x Zr 1-y Ti y O 3 (PLZT, wherein 0<x<1 and 0<y<1), Pb(Mg 1/3 Nb 2/3 )O 3 —PbTiO 3 (PMN-PT), hafnia (HfO 2 ), SrTiO 3 , SnO 2 , CeO 2 , MgO, Mg(OH) 2 , NiO, CaO, ZnO, ZrO 2 , Y 2 O 3 , SiO 2 , Al 2 O 3 , AlOOH, Al(OH) 3 , SiC, or TiO 2 .

11 . The separator for the lithium secondary battery according to claim 1 , wherein the second inorganic particles comprise at least one of BaTiO 3 , BaSO 4 , Pb(Zr,Ti)O 3 (PZT), Pb 1-x La x Zr 1-y Ti y O 3 (PLZT, wherein 0<x<1 and 0<y<1), Pb(Mg 1/3 Nb 2/3 )O 3 —PbTiO 3 (PMN-PT), hafnia (HfO 2 ), SrTiO 3 , SnO 2 , CeO 2 , MgO, Mg(OH) 2 , NiO, CaO, ZnO, ZrO 2 , Y 2 O 3 , SiO 2 , Al 2 O 3 , AlOOH, Al(OH) 3 , SiC, or TiO 2 .

12 . The separator for the lithium secondary battery according to claim 1 , wherein a weight ratio of the first inorganic particles to the second inorganic particles is from 90:10 to 40:60.

13 . The separator for the lithium secondary battery according to claim 1 , wherein the binder polymer comprises at least one of polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, acrylic polymer, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinylalcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile-styrene-butadiene copolymer, or polyimide.

14 . The separator for the lithium secondary battery according to claim 1 , wherein the porous coating layer has a packing density of 0.5 to 3.0 g/cm 3 .

15 . The separator for the lithium secondary battery according to claim 1 , which has a heat shrinkage of 10% or less in each of a machine direction (MD) and a transverse direction (TD), after the separator is allowed to stand at 130° C. for 1 hour.

16 . The separator for the lithium secondary battery according to claim 1 , wherein a peel strength between the porous polymer substrate and the porous coating layer is 30 gf/15 mm or more.

17 . A lithium secondary battery, comprising:
a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, wherein the separator is the separator for the lithium secondary battery as defined in claim 1 .

Assignees

• Lg Energy Solution Ltd

Inventors

• Noh Seong-Hee
• Park Su-Jin

Classifications

• H01M50/42

  Acrylic resins · CPC title

• H01M50/449

  having a layered structure · CPC title

• H01M50/417

  Polyolefins · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M50/403

  Manufacturing processes of separators, membranes or diaphragms · CPC title