Electrolyte for lithium secondary battery and lithium secondary battery including the same

1. An electrolyte for a lithium secondary battery, the electrolyte comprising a lithium salt, a non-aqueous organic solvent, and an additive represented by Formula 1 below:

wherein A 1 to A 9 are each, independently,

with the proviso that A 1 to A 9 include at least one of

CY1 is a C3-C6 aromatic ring, and CY2 is a C3-C5 aromatic or non-aromatic ring;

B 1 and B 2 are each independently a single bond,

 or a C1-C5 alkylene group;

and R 1 and R 2 are each independently hydrogen, a halogen group, a cyano group, a hydroxyl group, —C(═O)R a , —C(═O)OR a , —OCO(OR a ), —C═N(R a ), —SR a , —S(═O)R a , —S(═O) 2 R a , —PR a , a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1 -C20 alkoxy group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a C2-C20 alkylene oxide group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C6-C30 aryloxy group, a substituted or unsubstituted C6-C30 heteroaryl group, or combinations thereof, wherein R a is a C1-C10 alkyl group, or a C6-C20 aryl group, with the proviso that at least one of R 1 and R 2 includes a polar functional group selected from the group consisting of a halogen group, —C(═O)R a , —C(═O)OR a , —OCO(OR a ), C═N(R a ), —SR a , —PR a , a substituted or unsubstituted C1-C20 alkoxy group, a C2-C20 alkylene oxide group, a substituted or unsubstituted C6-C30 aryloxy group, and a substituted or unsubstituted C6-C30 heteroaryl group, and with the proviso that at least one of R 1 is SR a , wherein R a is a C1-C10 alkyl group, or a C6-C20 aryl group, wherein a film that is partially or fully derived from the additive in the electrolyte is formed on a surface of a positive electrode in the lithium secondary battery.

2. The electrolyte of claim 1 , wherein the additive is represented by Formula 2 below:

wherein A 1 and A 2 are each, independently,

with the proviso that A 1 and A 2 include at least one of

B 3 and B 4 are each independently a single bond,

 or a C1-C5alkylene group; and

R′ 1 , R″ 1 , R″ 2 , R″ 3 , and R″ 4 are each independently hydrogen, a halogen group, a hydroxyl group, a cyano group, —C(═O)R a , —C(═O)OR a , —OCO(OR a ), —C═N(R a ), —SR a , —S(═O)R a , —S(═O) 2 R a , —PR a , a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C2-C20alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a C2-C20alkylene oxide group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C6-C30aryloxy group, a substituted or unsubstituted C6-C30 heteroaryl group, or a combination thereof, wherein R a is a C1-C10 alkyl group, or a C6-C20 aryl group, with the proviso that at least one of R′ 1 , R″ 1 , R″ 2 , R″ 3 , and R″ 4 includes a polar functional group selected from the group consisting of a halogen group, —C(═O)R a , —C(═O)OR a , —OCO(OR a ), C═N(R a ), —SR a , —PR a , a substituted or unsubstituted C1-C20 alkoxy group, a C2-C20 alkylene oxide group, a substituted or unsubstituted C6-C30 aryloxy group, and a substituted or unsubstituted C6-C30 heteroaryl group, and with the proviso that at least one of R′ 2 , R″ 1 , R″ 2 , R″ 3 , and R″ 4 is —SR a , wherein R a is a C1-C10 alkyl group, or a C6C20 aryl group.

3. The electrolyte of claim 2 , wherein the additive is at least one compound selected from the group consisting of

4. The electrolyte of claim 3 , wherein the additive is at least one compound selected from the group consisting of

5. The electrolyte of claim 4 , wherein the additive is at least one compound selected from the group consisting of

6. The electrolyte of claim 1 , wherein the amount of the additive is in a range of about 0.005 to about 10 wt % based on the total weight of the electrolyte.

7. The electrolyte of claim 6 , wherein the amount of the additive is in a range of about 0.01 to about 5 wt % based on the total weight of the electrolyte.

8. The electrolyte of claim 1 , wherein the lithium salt is at least one compound selected from LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiCF 3 SO 3 , Li(CF 3 SO 2 ) 3 C, Li(CF 3 SO 2 ) 2 N, LiC 4 F 9 SO 3 , LiClO 4 , LiAlO 4 , LiAlCl 4 , LiBPh 4 , LiN(C x F 2x+1 SO 2 )(C x F 2y+1 SO 2 ) where x and y are natural numbers, LiCl, LiI, lithium bisoxalate borate (LIBOB), and combinations thereof.

9. The electrolyte of claim 1 , wherein the non-aqueous organic solvent is a carbonate-based solvent, an ester-based solvent, an ether-based solvent, a ketone-based solvent, an alcohol-based solvent, a non-protonic solvent, or combinations thereof.

10. A lithium secondary battery comprising:

a positive electrode comprising a positive active material into or from which lithium ions are intercalated or deintercalated;

a negative electrode comprising a negative active material into or from which lithium ions are intercalated or deintercalated; and

an electrolyte interposed between the positive electrode and the negative electrode,

wherein the electrolyte comprises a lithium salt, a non-aqueous organic solvent, and an additive represented by Formula 1 below:

wherein A 1 to A 9 are each, independently,

with the proviso that A 1 to A 9 include at least one of

CY1 is a C3-C6 aromatic ring, and CY2 is a C3-C5 aromatic or non-aromatic ring;

B 1 and B 2 are each independently a single bond,

 or a C1-C5 alkylene group; and

R 1 and R 2 are each independently hydrogen, a halogen group, a cyano group, a hydroxyl group, —C(═O)R a , —C(═O)OR a , —OCO(OR a ), —C═N(R a ), —SR a , —S(═O)R a , —S(═O) 2 R a , —PR a , a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20alkoxy group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a C2-C20 alkylene oxide group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C6-C30aryl group, a substituted or unsubstituted C6-C30 aryloxy group, a substituted or unsubstituted C6-C30heteroaryl group, or combinations thereof, wherein R a is a C1-C10 alkyl group, or a C6-C20 aryl group,

with the proviso that at least one of R 1 and R 2 includes a polar functional group selected from the group consisting of a halogen group, —C(═O)R a , —C(═O)OR a , —OCO(OR a ), C═N(R a ), —SR a , —PR a , a substituted or unsubstituted C1-C20 alkoxy group, a C2-C20 alkylene oxide group, a substituted or unsubstituted C6-C30aryloxy group, and a substituted or unsubstituted C6-C30 heteroaryl group, and with the proviso that at least one of R 1 is —SR a , wherein R a is a C1-C10 alkyl group or a C6-C20 aryl group, wherein a film that is partially or fully derived from the additive in the electrolyte is formed on a surface of a positive electrode in the lithium secondary battery.

11. The lithium secondary battery of claim 10 , wherein the additive is represented by Formula 2 below:

wherein A 1 and A 2 are each independently

 with the proviso that A 1 and A 2 include at least one of

B 3 and B 4 are each independently a single bond,

 or a C1-C5 alkylene group; and

R′ 1 , R″ 1 , R″ 2 , R″ 3 , and R″ 4 are each independently hydrogen, a halogen group, a hydroxyl group, a cyano group, —C(═O)R a , —C(═O)OR a , —OCO(OR a ), —C═N(R a ), —SR a , —S(═O)R a , —S(═O) 2 R a , —PR a , a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C2-C20alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a C2-C20 alkylene oxide group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C6-C30aryl group, a substituted or unsubstituted C6-C30 aryloxy group, a substituted or unsubstituted C6-C+heteroaryl group, or a combination thereof, wherein R a is a C1-C10 alkyl group, or a C6-C20 aryl group, with the proviso that at least one of R′ 1 , R″ 1 , R″ 2 , R″ 3 , and R″ 4 includes a polar functional group selected from the group consisting of a halogen group, —C(═O)R a , —C(═O)OR a , —OCO(OR a ), C═N(R a ), —SR a , —PR a , a substituted or unsubstituted C1-C20 alkoxy group, a C2-C20 alkylene oxide group, a substituted or unsubstituted C6-C30 aryloxy group, and a substituted or unsubstituted C6-C30heteroaryl group, and with the proviso that at least one of R′ 2 , R″ 1 , R″ 2 , R″ 3 , and R″ 4 is —SR a , wherein R a is a C1-C10 alkyl group or a C6-C20 aryl group.

12. The lithium secondary battery of claim 11 , wherein the additive is at least one compound selected from the group consisting of

13. The lithium secondary battery of claim 12 , wherein the additive is at least one compound selected from the group consisting of

14. The lithium secondary battery of claim 13 , wherein the additive is at least one compound selected from the group consisting of

15. The lithium secondary battery of claim 10 , wherein the thickness of the film is in a range of about 0.5 nm to about 100 nm.

16. The lithium secondary battery of claim 10 , wherein the amount of the additive is in a range of about 0.005 to about 10 wt % based on the total weight of the electrolyte.

17. The lithium secondary battery of claim 10 , wherein the amount of the additive is in a range of about 0.01 to about 5 wt % based on the total weight of the electrolyte.

18. The lithium secondary battery of claim 10 , wherein the positive active material is at least one material from the group LiCoO 2 , LiNi 1-x Co x O 2 where 0≦x< 1 , Li 1-x M x O 2 where M is Mn or Fe and 0.03<x<0.1, Li[Ni x Co 1-2x Mn x ]O 2 where 0<x<0.5, Li[Ni x Mn x ]O 2 where 0<x≦0.5, Li 1+x (M) 1-y O z where 0<x≦1, 0≦y<1, 2≦z≦4, and M is a transition metal, LiM 2 O 4 where M is Ti, V, or Mn, LiM x Mn 2-x O 4 where M is a transition metal, LiFePO 4 , LiMPO 4 where M is Mn, Co, or Ni, V 2 O 5 , V 2 O 3 , VO 2 (B), V 6 O 13 , V 4 O 9 , V 3 O 7 , Ag 2 V 4 O 11 , AgVO 3 , LiV 3 O 5 , δ-Mn y V 2 O 5 , δ-NH 4 V 4 O 10 , Mn 0.8 V 7 O 16 , LiV 3 O 8 , Cu x V 2 O 5 , Cr x V 6 O 13 , M 2 (XO 4 ) 3 where M is a transition metal and X is S, P, As, Mo, or W, and Li 3 M 2 (PO 4 ) 3 where M is Fe, V, or Ti.

19. The lithium secondary battery of claim 10 , wherein the positive active material is Li 1+x (M) 1-x O 2 0.05≦x≦0.2 and M is a transition metal.

20. The lithium secondary battery of claim 10 , wherein the positive active material has an operating potential of 4.5 V ±0.5 V.

21. The lithium secondary battery of claim 10 , wherein the negative active material is at least one material from the group vanadium oxide, lithium vanadium oxide, Si, SiO x where 0 <x <2, Si-T alloys where T is Mg, Ca, Sr, Ba, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Re, Fe, Pb, Ru, Os, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, or combinations thereof, graphite, soft carbon, hard carbon, meso-phase pitch carbide, and calcined coke.

22. The lithium secondary battery of claim 10 , wherein the lithium salt is at least one selected from LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiCF 3 SO 3 , Li(CF 3 SO 2 ) 3 C, Li(CF 3 SO 2 ) 2 N, LiC 4 F 9 SO 3 , LiClO 4 , LiAlO 4 , LiAlCl 4 , LiBPh 4 , LiN(C x F 2x+1 SO 2 )(C x F 2y+1 SO 2 ) where x and y are natural numbers, LiCl, LiI, lithium bisoxalate borate (LIBOB), and combinations thereof.

23. The lithium secondary battery of claim 10 , wherein the non-aqueous organic solvent is a carbonate-based solvent, an ester-based solvent, an ether-based solvent, a ketone-based solvent, an alcohol-based solvent, a non-protonic solvent, or combinations thereof.