Separator for rechargeable battery and rechargeable lithium battery including the same

1. A separator for a rechargeable battery comprising a porous substrate and a heat resistance layer on at least one surface of the porous substrate, wherein the heat resistance layer includes an acryl-based heat resistance binder, a water-soluble binder, and a filler, and

the acryl-based heat resistance binder includes a structural unit derived from (meth)acrylate or (meth)acrylic acid, a cyano group-containing structural unit, and a sulfonate group-containing structural unit, and

wherein the structural unit derived from (meth)acrylic acid is included in the acryl-based heat resistance binder in an amount of about 20 mol % to about 60 mol %,

the cyano group-containing structural unit is included in the acryl-based heat resistance binder in an amount of about 30 mol % to about 70 mol %, and

the sulfonate group-containing structural unit is included in the acryl-based heat resistance binder in an amount of about 0.1 mol % to about 20 mol %.

2. The separator for a rechargeable battery of claim 1 , wherein the water-soluble binder is a binder including at least one functional group selected from a hydroxyl group or a carboxyl group.

3. The separator for a rechargeable battery of claim 1 , wherein the a structural unit derived from (meth)acrylic acid includes one or more moieties represented by Chemical Formula 1, Chemical Formula 2, and Chemical Formula 3:

wherein, in Chemical Formula 1 to Chemical Formula 3,

R 1 , R 2 and R 3 are independently hydrogen or a methyl group, and

in Chemical Formula 2,

M is an alkali metal.

4. The separator for a rechargeable battery of claim 1 , wherein the cyano group-containing structural unit is a moiety represented by Chemical Formula 4:

wherein, in Chemical Formula 4,

R 4 is hydrogen or a C1 to C3 alkyl group, L 1 is —C(═O)—, —C(═O)O—, —OC(═O)—, —O—, or —C(═O)NH—,

x is an integer 0 to 2,

L 2 is 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, and

y is an integer ranging from 0 to 2.

5. The separator for a rechargeable battery of claim 1 , wherein the sulfonate group-containing structural unit includes one or more moieties represented by Chemical Formula 5, Chemical Formula 6, and Chemical Formula 7:

wherein, in Chemical Formula 5 to Chemical Formula 7,

R 5 , R 6 , and R 7 are independently hydrogen or a C1 to C3 alkyl group,

L 3 , L 5 , and L 7 are independently —C(═O)—, —C(═O)O—, —OC(═O)—, —O—, or —C(═O)NH—,

L 4 , L 6 , and L 8 are 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, and

a, b, c, d, e, and f are independently an integer ranging from 0 to 2,

in Chemical Formula 6,

M′ is an alkali metal.

6. The separator for a rechargeable battery of claim 1 , wherein a weight average molecular weight of the acryl-based heat resistance binder ranges from 200,000 g/mol to 700,000 g/mol.

7. The separator for a rechargeable battery of claim 1 , wherein a glass transition temperature of the acryl-based heat resistance binder ranges from 200° C. to 280° C.

8. The separator for a rechargeable battery of claim 1 , wherein the aryl-based heat resistance binder includes an alkali metal.

9. The separator for a rechargeable battery of claim 1 , wherein the acryl-based heat resistance binder and the water-soluble binder are included in a weight ratio of 2:8 to 8:2.

10. The separator for a rechargeable battery of claim 1 , wherein the water-soluble binder is a cellulose-based binder.

11. The separator for a rechargeable battery of claim 10 , wherein the cellulose-based binder is represented by Chemical Formula 9,

wherein, in Chemical Formula 9,

R's are independently —OH or R′COOH, and

R′ is 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.

12. The separator for a rechargeable battery of claim 11 , wherein the cellulose-based binder is selected from carboxyl methyl cellulose, hydroxypropyl cellulose, and diacetyl cellulose, or a combination thereof.

13. The separator for a rechargeable battery of claim 1 , wherein a weight average molecular weight of the water-soluble binder ranges from 50,000 g/mol to 800,000 g/mol.

14. A rechargeable lithium battery comprising

a positive electrode,

a negative electrode, and

the separator of claim 1 disposed between the positive electrode and the negative electrode.