Binder composition for lithium secondary battery, electrode for lithium secondary battery including the binder composition, and lithium secondary battery including the electrode

1. A binder composition for a lithium secondary battery, the binder composition comprising an interpenetrating network structure that includes:

a cyclic polymer, the cyclic polymer including a repeating unit represented by Formula 1 or a repeating unit represented by Formula 2; and

a copolymer, the copolymer including a repeating unit represented by Formula 3 and a repeating unit represented by Formula 4,

wherein an amount of the repeating unit represented by Formula 3 is about 40 mol % to about 70 mol %, based on a total amount of the copolymer:

wherein, in Formulae 1 and 2, R 1 , R 2 , R 11 , R 12 , R 14 , and R 15 are each independently a hydrogen atom, a substituted or unsubstituted C1-C5 alkyl group, a substituted or unsubstituted C2-C5 alkenyl group, a substituted or unsubstituted C2-C5 alkynyl group, or —(CH 2 ) p —COOX 1 , in which p is an integer of 1 to 5 and X 1 is an alkali metal,

R 3 , R 13 , and R 16 are each independently —OR 4 , —NHR 5 , or —COOX 2 ,

R 4 is a hydrogen atom, a substituted or unsubstituted C1-C5 alkyl group, a substituted or unsubstituted C2-C5 alkenyl group, a substituted or unsubstituted C2-C5 alkynyl group, or —(CH 2 ) p —COOX 1 , in which p is an integer of 1 to 5 and X 1 is an alkali metal,

R 5 is a hydrogen atom or —COCH 3 ,

X 2 is an alkali metal, and

n and m are each independently an integer of 5 to 20,000,

wherein, in Formula 3, R 6 and R 7 are each independently a hydrogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C5 alkenyl group, or a substituted or unsubstituted C2-C5 alkynyl group,

wherein, in Formula 4, R 4 and R 5 are each independently a hydrogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C5 alkenyl group, or a substituted or unsubstituted C2-C5 alkynyl group.

2. The binder composition as claimed in claim 1 , wherein a molar ratio of the cyclic polymer and the copolymer is about 1:9 to about 5:5.

3. The binder composition of claim 1 , wherein the copolymer including the repeating unit represented by Formula 3 and the repeating unit represented by Formula 4 is a copolymer represented by Formula 5:

wherein, in Formula 5, n is about 0.4 to about 0.7, and m is about 0.3 to about 0.6.

4. The binder composition as claimed in claim 1 , wherein the cyclic polymer includes a repeating unit represented by one of Formulae 3-1 to 3-6:

wherein, in Formulae 3-1 to 3-6, n1 to n5 and m1 are each independently an integer of 5 to 20,000.

5. The binder composition as claimed in claim 1 , wherein a weight average molecular weight of the copolymer is about 700,000 g/mol to about 900,000 g/mol.

6. The binder composition as claimed in claim 1 , wherein a weight average molecular weight of the cyclic polymer is about 2,000 g/mol to about 2,000,000 g/mol.

7. The binder composition as claimed in claim 1 , wherein a pH of the binder composition is about 6.0 to about 8.0.

8. An electrode for a lithium secondary battery, the electrode comprising:

an electrode active material; and

the binder composition as claimed in claim 1 .

9. The electrode as claimed in claim 8 , wherein the electrode active material includes Si, SiO x , in which 0<x<2, a Si—C composite, a Si-Q alloy, in which Q is an alkali metal, an alkaline-earth metal, an element of Group 13 to Group 16, a transition metal, a rare-earth element, or a combination thereof, but not Si, graphite, or a combination thereof.

10. The electrode as claimed in claim 8 , wherein a molar ratio of the cyclic polymer and the copolymer is about 1:9 to about 5:5.

11. The electrode as claimed in claim 8 , wherein the copolymer including the repeating unit represented by Formula 3 and the repeating unit represented by Formula 4 is a copolymer represented by Formula 5:

wherein, in Formula 5, n is about 0.4 to about 0.7, and m is about 0.3 to about 0.6.

12. The electrode as claimed in claim 8 , wherein the cyclic polymer includes a repeating unit represented by one of Formulae 3-1 to 3-6:

wherein, in Formulae 3-1 to 3-6, n1 to n5 and m1 are each independently an integer of 5 to 20,000.

13. The electrode as claimed in claim 8 , wherein a weight average molecular weight of the copolymer is about 700,000 g/mol to about 900,000 g/mol.

14. The electrode as claimed in claim 8 , wherein a weight average molecular weight of the cyclic polymer is about 2,000 g/mol to about 2,000,000 g/mol.

15. The electrode as claimed in claim 8 , wherein a pH of the binder composition is about 6.0 to about 8.0.

16. A lithium secondary battery, comprising:

a cathode;

an anode; and

an electrolyte,

wherein at least one of the cathode and the anode is the electrode as claimed in claim 8 .