Electrolyte for secondary battery, method of preparing electrolyte, and secondary battery including electrolyte

1. A secondary battery, comprising:

a positive electrode;

a negative electrode comprising a lithium metal or a lithium metal alloy; and

an electrolyte, wherein the electrolyte is disposed between the positive electrode and the negative electrode, and wherein the electrolyte is disposed on at least one portion of the negative electrode as a layer, a film, or a sheet,

wherein the electrolyte comprise an ionic polymer comprising a repeating unit represented by Formula 1:

wherein, in Formula 1,

CY is selected from a substituted or unsubstituted non-fused 6-membered aromatic ring, a substituted or unsubstituted fused C 10 -C 30 6-membered aromatic ring, and a combination of at least two of the foregoing aromatic rings, wherein the at least two of the foregoing aromatic rings are linked through a single bond or a C 1 -C 20 alkylene group;

R 1 , R 2 , and R 3 are each independently selected from a hydrogen atom, a halogen atom, a cyano group, a hydroxy group, a substituted or unsubstituted C 1 -C 20 alkyl group, a substituted or unsubstituted C 1 -C 20 alkoxy group, a substituted or unsubstituted C 1 -C 20 heteroalkyl group, a substituted or unsubstituted C 3 -C 20 cycloalkyl group, a substituted or unsubstituted C 3 -C 20 cycloalkyloxy group, a substituted or unsubstituted C 3 -C 30 heterocycloalkyl group, a substituted or unsubstituted C 6 -C 30 aryl group, an unsubstituted C 7 -C 30 arylalkyl group, a substituted or unsubstituted C 6 -C 30 aryloxy group, a substituted or unsubstituted C 3 -C 30 heteroaryl group, a substituted or unsubstituted C 4 -C 30 heteroarylalkyl group, a substituted or unsubstituted C 3 -C 30 heteroaryloxy group, and a C 2 -C 20 alkylene oxide group, and a combination thereof, provided that R 3 is not an arylalkyl group substituted with a C 2 alkene;

n is an integer up to 5,000, and m is an integer selected from 1 to 1,000, wherein the ionic polymer has a weight average molecular weight from about 500 Daltons to about 1,000,000 Daltons; and

X 1 − is at least one anion selected from BF 4 − , PF 6 − , AsF 6 − , SbF 6 − , AlCl 4 − , HSO 4 − , CH 3 SO 3 − , (CF 3 SO 2 ) 2 N − , Cl − , Br − , I − , SO 4 − , PF 6 − , ClO 4 − , CF 3 SO 3 − , CF 3 CO 2 − , (C 2 F 5 SO 2 ) 2 N − , (C 2 F 5 SO 2 )(CF 3 SO 2 )N − , (CF 3 SO 2 ) 2 N − , NO 3 − , Al 2 Cl 7 − , AsF 6 − , SbF 6 − , CH 3 COO − , (CF 3 SO 2 ) 3 C − , (CF 3 ) 2 PF 4 − , (CF 3 ) 3 PF 3 − , (CF 3 ) 4 PF 2 − , (CF 3 ) 5 PF − , (CF 3 ) 6 P − , SF 5 CF 2 SO 3 − , SF 5 CHFCF 2 SO 3 − , CF 3 CF 2 (CF 3 ) 2 CO − , (CF 3 SO 2 ) 2 CH − , (SF 5 ) 3 C − , and (O(CF 3 ) 2 C 2 (CF 3 ) 2 O) 2 PO − .

2. The secondary battery of claim 1 , wherein CY comprises 6-membered aromatic ring selected from a substituted or unsubstituted benzene ring, a substituted or unsubstituted naphthalene ring, a substituted or unsubstituted anthracene ring, a substituted or unsubstituted phenalene ring, a substituted or unsubstituted phenanthrene ring, a substituted or unsubstituted pyrene ring, a substituted or unsubstituted chrysene ring, a substituted or unsubstituted naphthacene ring, a substituted or unsubstituted picene ring, a substituted or unsubstituted pentaphene ring, and a substituted or unsubstituted hexacene ring, or a combination of at least two of the foregoing linked through a single bond or a C 1 -C 20 alkylene group.

3. The secondary battery of claim 1 , wherein m is an integer selected from 1 to 100.

4. The secondary battery of claim 1 , wherein a weight average molecular weight of the ionic liquid polymer is in a range of about 10,000 Daltons to about 100,000 Daltons.

5. The secondary battery of claim 1 , wherein the ionic liquid polymer is represented by Formula 2:

wherein, in Formula 2,

R 1 ′, R 2 ′, and R 3 ′ are each independently selected from a hydrogen atom, a halogen atom, a cyano group, a hydroxy group, a substituted or unsubstituted C 1 -C 20 alkyl group, a substituted or unsubstituted C 1 -C 20 alkoxy group, a substituted or unsubstituted C 1 -C 20 heteroalkyl group, a substituted or unsubstituted C 3 -C 20 cycloalkyl group, a substituted or unsubstituted C 3 -C 20 cycloalkyloxy group, a substituted or unsubstituted C 3 -C 30 heterocycloalkyl group, a substituted or unsubstituted C 6 -C 30 aryl group, an unsubstituted C 7 -C 30 arylalkyl group, a substituted or unsubstituted C 6 -C 30 aryloxy group, a substituted or unsubstituted C 3 -C 30 heteroaryl group, a substituted or unsubstituted C 4 -C 30 heteroarylalkyl group, a substituted or unsubstituted C 3 -C 30 heteroaryloxy group, and a C 2 -C 20 alkylene oxide group, and a combination thereof, provided that R′ 3 is not an arylalkyl group substituted with a C 2 alkene;

p is an integer up to 500, q is an integer selected from 1 to 100, wherein a weight average molecular weight of the ionic liquid polymer is in a range of about 10,000 Daltons to about 1,000,000 Daltons; and

X 1 − is at least one anion selected from BF 4 − , PF 6 − , AsF 6 − , SbF 6 − , AlCl 4 − , HSO 4 − , CH 3 SO 3 − , (CF 3 SO 2 ) 2 N − , Cl − , Br − , I − , SO 4 − , PF 6 − , ClO 4 − , CF 3 SO 3 − , CF 3 CO 2 − , (C 2 F 5 SO 2 ) 2 N − , (C 2 F 5 SO 2 )(CF 3 SO 2 )N − , (CF 3 SO 2 ) 2 N − , NO 3 − , Al 2 Cl 7 − , AsF 6 − , SbF 6 − , CH 3 COO − , (CF 3 SO 2 ) 3 C − , (CF 3 ) 2 PF 4 − , (CF 3 ) 3 PF 3 − , (CF 3 ) 4 PF 2 − , (CF 3 ) 5 PF − , (CF 3 ) 6 P − , SF 5 CF 2 SO 3 − , SF 5 CHFCF 2 SO 3 − , CF 3 CF 2 (CF 3 ) 2 CO − , (CF 3 SO 2 ) 2 CH − , (SF 5 ) 3 C − , and (O(CF 3 ) 2 C 2 (CF 3 ) 2 O) 2 PO − .

6. The secondary battery of claim 1 , wherein the electrolyte comprises at least one selected from an alkali metal salt and an alkaline earth metal salt.

7. The secondary battery of claim 6 , wherein the at least one selected from an alkali metal salt and an alkaline earth metal salt comprises at least one selected from LiSCN, LiN(CN) 2 , LiClO 4 , LiBF 4 , LiAsF 6 , LiPF 6 , LiCF 3 SO 3 , Li(CF 3 SO 2 ) 2 N, Li(CF 3 SO 2 ) 3 C, LiN(SO 2 F) 2 , LiN(SO 2 CF 3 ) 2 , LiN(SO 2 CF 2 CF 3 ) 2 , LiSbF 6 , LiPF 3 (CF 2 CF 3 ) 3 , LiPF 3 (CF 3 ) 3 , LiB(C 2 O 4 ) 2 , NaSCN, NaSO 3 CF 3 , KTFSI, NaTFSI, Ba(TFSI) 2 , Pb(TFSI) 2 , and Ca(TFSI) 2 .

8. The secondary battery of claim 6 , wherein an amount of the alkali metal salt and the alkaline earth metal salt is in a range of about 0.01 part by weight to about 100 parts by weight based on 100 parts by weight of the ionic liquid polymer.

9. The secondary battery of claim 1 , wherein the electrolyte further comprises at least one selected from a liquid electrolyte, a solid electrolyte, a gel electrolyte, a plurality of inorganic particles, and a separator.

10. A method of preparing an electrolyte for a secondary battery, the method comprising:

providing a monomer represented by Formula 3;

in-situ polymerizing the monomer represented by Formula 3 to obtain the electrolyte according to claim 1 ;

wherein, in Formula 3,

CY1 is selected from a substituted or unsubstituted non-fused 6-membered aromatic ring, a substituted or unsubstituted fused C 10 -C 30 6-membered aromatic ring, and a combination of at least two of the foregoing aromatic rings, wherein the at least two of the foregoing aromatic rings are linked through a single bond or a C 1 -C 20 alkylene group;

R 4 is selected from a halogen atom, a cyano group, a hydroxy group, a substituted or unsubstituted C 1 -C 20 alkyl group, a substituted or unsubstituted C 1 -C 20 alkoxy group, a substituted or unsubstituted heteroalkyl group, a substituted or unsubstituted C 3 -C 20 cycloalkyl group, a substituted or unsubstituted C 3 -C 20 cycloalkyloxy group, a substituted or unsubstituted C 3 -C 30 heterocycloalkyl group, a substituted or unsubstituted C 6 -C 30 aryl group, a substituted or unsubstituted C 7 -C 30 arylalkyl group, a substituted or unsubstituted C 6 -C 30 aryloxy group, a substituted or unsubstituted C 3 -C 30 heteroaryl group, a substituted or unsubstituted C 4 -C 30 heteroarylalkyl group, a substituted or unsubstituted C 3 -C 30 heteroaryloxy group, and a C 2 -C 20 alkylene oxide group, and a combination thereof, provided that R 4 is not an arylalkyl group substituted with a C 2 alkene;

m 1 is an integer selected from 1 to 1,000; and

X 2 − is at least one anion selected from BF 4 − , PF 6 − , AsF 6 − , SbF 6 − , AlCl 4 − , HSO 4 − , CH 3 SO 3 − , (CF 3 SO 2 ) 2 N − , Cl − , Br − , I − , SO 4 − , PF 6 − , ClO 4 − , CF 3 SO 3 − , CF 3 CO 2 − , (C 2 F 5 SO 2 ) 2 N − , (C 2 F 5 SO 2 )(CF 3 SO 2 )N − , (CF 3 SO 2 ) 2 N − , NO 3 − , Al 2 Cl 7 − , AsF 6 − , SbF 6 − , CH 3 COO − , (CF 3 SO 2 ) 3 C − , (CF 3 ) 2 PF 4 − , (CF 3 ) 3 PF 3 − , (CF 3 ) 4 PF 2 − , (CF 3 ) 5 PF − , (CF 3 ) 6 P − , SF 5 CF 2 SO 3 − , SF 5 CHFCF 2 SO 3 − , CF 3 CF 2 (CF 3 ) 2 CO − , (CF 3 SO 2 ) 2 CH − , (SF 5 ) 3 C − , and (O(CF 3 ) 2 C 2 (CF 3 ) 2 O) 2 PO − .

11. The method of claim 10 , wherein the in-situ polymerizing comprises thermal in-situ polymerization or ultra-violet in-situ polymerization at room temperature.

12. The method of claim 10 , wherein the electrolyte further comprises at least one selected from an alkali metal salt and an alkaline earth metal salt.

13. The method of claim 12 , wherein the at least one selected from an alkali metal salt and an alkaline earth metal salt comprises at least one selected from LiSCN, LiN(CN) 2 , LiClO 4 , LiBF 4 , LiAsF 6 , LiPF 6 , LiCF 3 SO 3 , Li(CF 3 SO 2 ) 2 N, Li(CF 3 SO 2 ) 3 C, LiN(SO 2 F) 2 , LiN(SO 2 CF 3 ) 2 , LiN(SO 2 CF 2 CF 3 ) 2 , LiSbF 6 , LiPF 3 (CF 2 CF 3 ) 3 , LiPF 3 (CF 3 ) 3 , LiB(C 2 O 4 ) 2 , NaSCN, NaSO 3 CF 3 , KTFSI, NaTFSI, Ba(TFSI) 2 , Pb(TFSI) 2 , and Ca(TFSI) 2 .

14. The method of claim 12 , wherein an amount of the alkali metal salt and the alkaline earth metal salt is in a range of about 0.01 part by weight to about 100 parts by weight based on 100 parts by weight of the monomer for forming an ionic liquid polymer.

15. The secondary battery of claim 1 , wherein the electrolyte further comprises at least one selected from a liquid electrolyte, a solid electrolyte, a gel electrolyte, a plurality of inorganic particles, and a separator.

16. The secondary battery of claim 1 , wherein a thickness of the layer, the film, or the sheet is in a range of about 0.1 micrometer to about 100 micrometers.

17. The secondary battery of claim 1 , wherein an operation potential of the secondary battery is in a range of about −0.1 Volts to about 4.5 Volts versus Li/Li + .