Separator for lithium secondary battery, and lithium secondary battery comprising same

Patent metadata

Field	Value
Publication number	US-12562435-B2
Application number	US-201917416686-A
Country	US
Kind code	B2
Filing date	Aug 9, 2019
Priority date	Jan 4, 2019
Publication date	Feb 24, 2026
Grant date	Feb 24, 2026

Abstract

The present invention relates to a separator for a lithium secondary battery, and a lithium secondary battery including the same, the separator including a porous substrate and a coating layer located on at least one surface of the porous substrate, wherein the coating layer includes a heat-resistant binder including a (meth)acrylic copolymer including a first structural unit derived from (meth)acrylamide, a second structural unit derived from (meth)acrylonitrile, and a third structural unit derived from (meth)acrylaminosulfonic acid, a (meth)acrylaminosulfonate or a combination thereof; an adhesive binder having a core-shell structure; and inorganic particles, wherein the adhesive binder has an average particle diameter of 0.2 μm to 1.0 μm, and the inorganic particles have an average particle diameter of 0.2 μm to 1.0 μm.

First claim

The invention claimed is:

1 . A separator for a lithium secondary battery, comprising
a porous substrate, and a coating layer comprising
a heat-resistant layer on at least one surface of the porous substrate,
an adhesive layer on the heat-resistant layer,
inorganic particles, and
an organic filler,
the heat-resistant layer comprising a heat-resistant binder comprising a (meth)acrylic copolymer comprising
a first structural unit derived from (meth)acrylamide,
a second structural unit derived from (meth)acrylonitrile, and
a third structural unit derived from (meth)acrylamidosulfonic acid, a (meth)acrylamidosulfonate salt, or a combination thereof,

the adhesive layer comprising an adhesive binder having a core-shell structure and an average particle diameter of 0.2 μm to 1.0 μm,
the inorganic particles excluding silica (SiO 2 ) and having an average particle diameter of 0.3 μm to 1.0 μm, and

a ratio of a volume of inorganic particles to a sum of a volume of the adhesive binder and a volume of the organic filler is 33:1 to 1:1.

2 . The separator of claim 1 , wherein the adhesive binder is a (meth)acrylic polymer including a structural unit derived from (meth)acrylic acid or (meth)acrylate and a structural unit derived from a monomer having a polymerizable unsaturated group.

3 . The separator of claim 2 , wherein the monomer having the polymerizable unsaturated group is at least one selected from a styrene-based monomer, an acid-derived monomer, and a combination thereof.

4 . The separator of claim 3 , wherein the acid-derived monomer is at least one selected from itaconic acid, acrylic acid, and a combination thereof.

5 . The separator of claim 1 , wherein the adhesive binder is included in an amount of 1 to 20 wt % based on the total amount of the coating layer.

6 . The separator of claim 1 , wherein a weight ratio of the heat-resistant binder including the (meth)acrylic copolymer: the inorganic particles is 1:20 to 1:40.

7 . The separator of claim 1 , wherein
the heat-resistant layer has a thickness of 1 μm to 5 μm, and the adhesive layer has a thickness of 0.4 μm to 1.4 μm.

8 . The separator of claim 1 , wherein
the organic filler is included in at least one of the heat-resistant layer and the adhesive layer.

9 . The separator of claim 8 , wherein the organic filler has an average particle diameter of 120 nm to 500 nm.

10 . The separator of claim 1 , wherein
the first structural unit derived from (meth)acrylamide is represented by Chemical Formula 1, the second structural unit derived from the (meth)acrylonitrile is represented by Chemical Formula 2, and the third structural unit derived from the (meth)acrylamidosulfonic acid, (meth)acrylamidosulfonate salt, or combination thereof is represented by one of Chemical Formula 3, Chemical Formula 4, Chemical Formula 5, or a combination thereof:

wherein, in Chemical Formula 1 to Chemical Formula 5,
R 1 is hydrogen or a methyl group,
R 2 , R 3 , R 4 , and R 5 are each independently hydrogen or a C1 to C3 alkyl group,
L 1 , L 3 , L 5 , and L 7 are each independently —C(═O)—, —C(═O)O—, —OC(═O)—, —O—, or —C(═O)NH—,
L 2 , L 4 , L 6 , and L 8 are each independently a substituted or unsubstituted C1 to C10 alkylene group, a substituted or unsubstituted C3 to C20 cycloalkylene group, a substituted or unsubstituted C6 to C20 arylene group, or a substituted or unsubstituted C3 to C20 heterocyclic group,
x and y are each independently an integer of 0 to 2,
a, b, c, d, e, and f are each independently an integer of 0 to 2, and
M + is an alkali metal.

11 . A lithium secondary battery, comprising
a positive electrode, a negative electrode, and the separator for the lithium secondary battery of claim 1 between the positive electrode and the negative electrode.

12 . The separator of claim 1 , wherein the core-shell structure comprises a shell that is a continuous layer comprising polymer particles,
the polymer particles being overlapped in a radial direction of the polymer particles or in a form of a single layer.

13 . The separator of claim 12 , wherein the polymer particles are overlapped in the radial direction of the polymer particles.

14 . The separator of claim 12 , wherein the polymer particles are in the form of the single layer.

15 . The separator of claim 1 , wherein the heat-resistant layer further comprises the inorganic particles.

16 . The separator of claim 1 , wherein
the first structural unit derived from (meth)acrylamide is included in an amount of 85 mol % to 99 mol % based on 100 mol % of the (meth)acrylic copolymer, the second structural unit derived from the (meth)acrylonitrile is included in an amount of 0.5 mol % to 10 mol % based on 100 mol % of the (meth)acrylic copolymer, and the third structural unit derived from the (meth)acrylamidosulfonic acid, (meth)acrylamidosulfonate salt, or combination thereof is included in an amount of 0.5 to 5 mol % based on 100 mol % of the (meth)acrylic copolymer.

17 . The separator of claim 1 , wherein the inorganic particles have an average particle diameter of 0.3 μm to 0.7 μm.

18 . The separator of claim 1 , wherein the ratio is 5:1 to 1:1.

19 . The separator of claim 1 , wherein the inorganic particles consist of Al 2 O 3 , TiO 2 , SnO 2 , CeO 2 , MgO, NiO, CaO, GaO, ZnO, ZrO 2 , Y 2 O 3 , SrTiO 3 , BaTiO 3 , Mg(OH) 2 , boehmite, or a combination thereof.

20 . The separator of claim 1 , wherein the organic filler is at least one selected from among (meth)acrylates, polyimides, diallyl phthalates, derivatives thereof, copolymers thereof, and combinations thereof.

Assignees

• Samsung Sdi Co Ltd

Inventors

• Kim Yongkyoung
• Kim Gain
• Lee Jungyoon
• Choi Yeonjoo
• Kim Yangseob

Classifications

• H01M50/443

  Particulate material · CPC title

• H01M10/0525

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

• C09D133/26

  Homopolymers or copolymers of acrylamide or methacrylamide · CPC title

• C09D133/12

  Homopolymers or copolymers of methyl methacrylate · CPC title

• C08L33/12

  Homopolymers or copolymers of methyl methacrylate · CPC title