Acrylic binder for lithium-sulfur secondary battery cathode
The present invention relates to a binder for a lithium-sulfur secondary battery cathode, and a composition containing the same. The binder of the present application enables a cathode active material electrolyte to have excellent resistance.
1. An acrylic binder for a lithium-sulfur secondary battery cathode, comprising a polymerized units of a polymerizable monomer having a polar functional group interacting with a cathode active material,
wherein the polar functional group comprises an alkylene oxide group, and optionally further comprises at least one selected from the group consisting of a nitrogen-containing functional group, a hydroxy group and an alkoxysilyl group.
2. The acrylic binder for a lithium-sulfur secondary battery cathode according to claim 1 ,
wherein the polymerizable monomer having a polar functional group is contained in the polymerized unit in an amount of 30 to 100 parts by weight.
3. The acrylic binder for a lithium-sulfur secondary battery cathode according to claim 1 ,
further comprising a polymerized unit of alkyl (meth)acrylate.
4. The acrylic binder for a lithium-sulfur secondary battery cathode according to claim 3 ,
wherein the alkyl (meth)acrylate is contained in the polymerized unit in an amount of 5 to 30 parts by weight.
5. The acrylic binder for a lithium-sulfur secondary battery cathode according to claim 1 ,
having a particle diameter of 10 nm or less.
6. The acrylic binder for a lithium-sulfur secondary battery cathode according to claim 1 ,
having a glass transition temperature in a range of −80° C. to 50° C.
7. The acrylic binder for a lithium-sulfur secondary battery cathode according to claim 1 ,
having a weight average molecular weight in a range of 5,000 to 3,000,000.
8. A composition for forming a cathode active layer of a lithium-sulfur secondary battery comprising the acrylic binder according to claim 1 , a cathode active material and a conductive material.
9. The composition for forming a cathode active layer of a lithium-sulfur secondary battery according to claim 8 ,
wherein the acrylic binder is contained in an amount of 0.01 to 10 parts by weight, relative to 100 parts by weight of a solid content of the composition.
10. The composition for forming a cathode active layer of a lithium-sulfur secondary battery according to claim 8 ,
wherein the cathode active material is a sulfur-carbon composite.
11. The composition for forming a cathode active layer of a lithium-sulfur secondary battery according to claim 8 ,
wherein the cathode active material is contained in an amount of 30 to 95 parts by weight, relative to 100 parts by weight of a solid content of the composition.
12. The composition for forming a cathode active layer of a lithium-sulfur secondary battery according to claim 8 ,
further comprising a non-acrylic binder.
13. The composition for forming a cathode active layer of a lithium-sulfur secondary battery according to claim 8 ,
wherein the conductive material is contained in an amount of 2 to 70 parts by weight, relative to 100 parts by weight of a solid content of the composition.
14. 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 .
15. The cathode for a lithium-sulfur secondary battery according to claim 14 , wherein the active layer has a thickness in a range of 1 to 200 μm.
16. A lithium-sulfur secondary battery comprising the cathode of claim 14 .
17. The cathode for a lithium-sulfur secondary battery according to claim 14 , wherein a cathode active material has a compound comprising a sulfur element.
18. The cathode for a lithium-sulfur secondary battery according to claim 17 , wherein the cathode active material is a sulfur-carbon composite.
19. The cathode for a lithium-sulfur secondary battery according to claim 17 , wherein the polar functional group of the acrylic binder interacts with the sulfur element.