Composite separator and electrochemical device including the same

Patent metadata

Field	Value
Publication number	US-12206130-B2
Application number	US-202117407382-A
Country	US
Kind code	B2
Filing date	Aug 20, 2021
Priority date	Aug 21, 2020
Publication date	Jan 21, 2025
Grant date	Jan 21, 2025

Abstract

Provided are a composite separator including a coating layer including inorganic particles and a binder formed on a porous substrate, which has improved coatability and improved thermal shrinkage, and a lithium secondary battery using the same.

First claim

What is claimed is:

1. A composite separator comprising:
a porous substrate; and
a coating layer consisting essentially of inorganic particles and a binder formed on one surface or both surfaces of the porous substrate,
wherein the binder comprises a copolymer comprising: (a) a unit derived from (meth)acrylamide; (b) a unit derived from (b-1) (meth)acrylic acid and (b-2) a (meth)acrylic acid salt; and (c) a unit derived from an addition-polymerizable monomer containing a sulfonate, and
wherein the unit derived from any one or more selected from (b-2) the (meth)acrylic acid salt is selected from a compound represented by the following Chemical Formula 3:

wherein R 3 is hydrogen or a C1 to C6 alkyl group, and M n+ is Li + , Na + , K + , NH 4 + , Ca 2+ , Mg 2+ , Al 3+ or Ga 3+ .

2. The composite separator of claim 1 , wherein (a) the unit derived from (meth)acrylamide is selected from a compound represented by the following Chemical Formula 1, the unit derived from (b-1) (meth)acrylic acid is selected from a compound represented by the following Chemical Formula 2, and (c) the unit derived from an addition-polymerizable monomer containing a sulfonate is selected from a compound represented by the following Chemical Formula 4:

wherein R 1 is hydrogen or a C1 to C6 alkyl group,

wherein R 2 is hydrogen or a C1 to C6 alkyl group,

wherein R 4 is selected from hydrogen or C1 to C6 alkyl groups, M n+ is a cation having an oxidation number of n, and n is an integer of 1 to 3.

3. The composite separator of claim 2 , wherein R 1 , R 2 , and R 3 are hydrogen, and R 4 is methyl.

4. The composite separator of claim 1 , wherein the copolymer further comprises a repeating unit derived from N-methylolacrylamide.

5. The composite separator of claim 1 ,
wherein the copolymer comprises: 49 to 98 mol % of (a), 1 to 50 mol % of (b-1)+(b-2), and 0.0001 to 1 mol % of (c), and
(b-1):(b-2) is at a mole ratio of 1:99 to 10:90.

6. The composite separator of claim 1 , wherein the binder further comprises a crosslinking agent.

7. The composite separator of claim 6 , wherein the crosslinking agent is any one or a mixture of two or more selected from glycol-based compounds and polyol compounds.

8. The composite separator of claim 1 , wherein the copolymer has a weight average molecular weight of 500,000 to 2,000,000 g/mol.

9. The composite separator of claim 1 , wherein a content ratio of the inorganic particles: the binder is 80:20 to 99.9:0.1 by weight.

10. The composite separator of claim 1 , wherein the composite separator has a thermal shrinkage rate both in a machine direction (MD) and in a transverse direction (TD) of 5% or less after being allowed to stand at 150° C. for 1 hr.

11. The composite separator of claim 10 , wherein the thermal shrinkage rate is 3% or less both in the machine direction and in the transverse direction.

12. The composite separator of claim 1 , wherein the coating layer is formed by applying a composition consisting essentially of the inorganic particles and the binder.

Assignees

• Sk Innovation Co Ltd
• Sk Ie Tech Co Ltd

Inventors

• Kim Sun Young
• Kwon Tae Wook
• Bae Heung Taek
• Lee Dong Gun
• Kim Yun Bong
• Seon Min Kyung

Classifications

• H01M10/052

  Li-accumulators · CPC title

• C08F20/56

  Acrylamide; Methacrylamide · CPC title

• C08F20/06

  Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof · CPC title

• H01M50/431

  Inorganic material · CPC title

• H01M50/449

  having a layered structure · CPC title