Acrylic binder for lithium-sulfur secondary battery cathode and use thereof

Patent metadata

Field	Value
Publication number	US-2020161658-A1
Application number	US-201716335643-A
Country	US
Kind code	A1
Filing date	Sep 26, 2017
Priority date	Sep 26, 2016
Publication date	May 21, 2020
Grant date	—

Abstract

A binder for a lithium-sulfur secondary battery cathode, a composition containing the same, and an acrylic binder capable of forming a cross-linked network and a use thereof. The binder contains a polar functional group capable of strongly interacting with sulfur.

First claim

1 . An acrylic binder for a lithium-sulfur secondary battery cathode, comprising polymerized units of a first polymerizable monomer having a polar functional group interacting with a cathode active material; and
polymerized units of a second polymerizable monomer having a cross-linkable functional group.

2 . The acrylic binder according to claim 1 ,
wherein the polar functional group is one or more selected from the group consisting of an amide group, a nitrile group and an alkylene oxide group.

3 . The acrylic binder according to claim 1 ,
wherein the cross-linkable functional group is one or more selected from the group consisting of an amine group, a hydroxy group, a carboxy group, an epoxy group and a vinyl group.

4 . The acrylic binder according to claim 1 ,
wherein the acrylic binder comprises polymerized units of 30 to 99.5 parts by weight of the first polymerizable monomer and polymerized units of 0.5 to 30 parts by weight of the second polymerizable monomer.

5 . The acrylic binder according to claim 1 ,
wherein the interaction is an interaction between the polar functional group and the sulfur element.

6 . The acrylic binder according to claim 1 ,
further comprising polymerized units of alkyl (meth)acrylate.

7 . The acrylic binder according to claim 6 ,
wherein the alkyl (meth)acrylate is contained in a polymerized unit ratio of 5 to 30 parts by weight.

8 . The acrylic binder according to claim 1 ,
wherein the acrylic binder has a particle diameter of 10 nm or less.

9 . The acrylic binder according to claim 1 ,
wherein the acrylic binder has a glass transition temperature in a range of −80° C. to 50° C.

10 . The acrylic binder according to claim 1 ,
wherein the acrylic binder has a weight average molecular weight in a range of 5,000 to 3,000,000.

11 . A composition for forming a cathode active layer of a lithium-sulfur secondary battery comprising the acrylic binder according to claim 1 , a cross-linking agent, a cathode active material and a conductive material.

12 . The composition for forming a cathode active layer of a lithium-sulfur secondary battery according to claim 11 ,
wherein the acrylic binder is contained in a ratio of 0.01 to 10 parts by weight, relative to 100 parts by weight of the solid content of the composition.

13 . The composition for forming a cathode active layer of a lithium-sulfur secondary battery according to claim 11 ,
wherein the cathode active material is a sulfur-carbon composite.

14 . The composition for forming a cathode active layer of a lithium-sulfur secondary battery according to claim 11 ,
wherein the cathode active material is contained in a ratio of 30 to 95 parts by weight, relative to 100 parts by weight of the solid content of the composition.

15 . The composition for forming a cathode active layer of a lithium-sulfur secondary battery according to claim 11 ,
wherein the cross-linking agent is contained in a ratio of 0.0001 to 1 part by weight, relative to 100 parts by weight of the solid content of the composition.

16 . The composition for forming a cathode active layer of a lithium-sulfur secondary battery according to claim 11 ,
wherein the conductive material is contained in a ratio of 2 to 70 parts by weight, relative to 100 parts by weight of the solid content of the composition.

17 . The composition for forming a cathode active layer of a lithium-sulfur secondary battery according to claim 11 ,
further comprising a conductive material dispersant, wherein the conductive material dispersant is contained in a ratio of 0.001 to 19.99 parts by weight, relative to 100 parts by weight of the solid content of the composition.

18 . The composition for forming a cathode active layer of a lithium-sulfur secondary battery according to claim 17 ,
wherein the conductive material dispersant is carboxymethyl cellulose.

19 . A cathode for a lithium-sulfur secondary battery having:
a current collector; and an active layer formed on the current collector and comprising the acrylic binder according to claim 1 .

20 . The cathode for a lithium-sulfur secondary battery according to claim 19 ,
wherein the active layer has a thickness in a range of 1 to 200 μm.

21 . A lithium-sulfur secondary battery comprising the cathode of claim 19 .

Assignees

• Lg Chemical Ltd

Inventors

• Yoon Jeong Ae
• Kim Yu Mi
• Lee Choong Hyeon
• Yang Doo Kyung
• Yoon Sung Soo

Classifications

• H01M4/13

  Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof · CPC title

• H01M4/38

  of elements or alloys · CPC title

• H01M4/587

  for inserting or intercalating light metals · CPC title

• H01M4/364

  as mixtures · CPC title

• H01M4/622 Primary

  being polymers · CPC title