Organic electrolytic solution and lithium-sulfur battery comprising the same
An organic electrolytic solution for a lithium-sulfur battery that provides high discharge capacity and longer cycle life to the battery, and a lithium-sulfur battery including the organic electrolytic solution are provided. The electrolytic solution includes a lithium salt, an organic solvent, and further a compound represented by Formula (I):
1. An electrolytic solution for a lithium-sulfur battery, comprising:
a lithium salt;
an organic solvent; and
a compound represented by Formula (I):
wherein R 1 is selected from the group consisting of a hydrogen atom, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C6-C30 aryl group, and a substituted or unsubstituted C8-C30 aralkenyl group;
R 2 represents a group of Formula II or III;
wherein R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are independently a hydrogen atom, a C1-C5 linear or branched alkyl group, or a C1-C5 linear or branched alkoxy group; and
X is an integer of 2 to 5.
2. The electrolytic solution of claim 1 , wherein an amount of the compound of Formula (I) is 0.1 to 20% by weight based on the weight of the electrolytic solution.
3. The electrolytic solution of claim 1 , wherein an amount of the compound of Formula (I) is 0.1 to 5% by weight based on the weight of the electrolytic solution.
4. The electrolytic solution of claim 1 , wherein the compound of Formula (I) is bis(2-trimethylsiloxy-2-phenylethyl) trisulfide.
5. The electrolytic solution of claim 1 , wherein R 1 of Formula (I) is selected from the group consisting of a substituted or unsubstituted C1-C12 alkyl group, a substituted or unsubstituted C6-C18 aryl group, a substituted or unsubstituted C1-C12 alkoxy group, and a substituted or unsubstituted C8-C18 aralkenyl group.
6. The electrolytic solution of claim 1 , wherein R 1 of Formula (I) is selected from the group consisting of a substituted or unsubstituted C1-C6 alkyl group, a substituted or unsubstituted C6-C12 aryl group, a substituted or unsubstituted C1-C6 alkoxy group, and a substituted or unsubstituted C8-C12 aralkenyl group.
7. The electrolytic solution of claim 1 , further comprising an electron conducting material.
8. The electrolytic solution of claim 7 , wherein the electron conducting material is selected from the group consisting of a carbon black, a graphite, a carbon fiber, an electron conducting compound having at least one of a conjugate carbon-carbon double bond and a carbon-nitrogen double bond, and mixtures thereof.
9. The lithium-sulfur battery comprising a cathode, an anode, a separator interposed between said cathode and said anode, and the electrolytic solution of claim 1 .
10. The electrolytic solution of claim 1 , wherein R 2 represents a group of Formula II.
11. The electrolytic solution of claim 1 , wherein R 2 represents a group of Formula III.
12. A lithium-sulfur battery, comprising
an anode including at least one anode active material;
a cathode including at least one cathode active material;
a separator interposed between the cathode and the anode to separate from each other; and
an organic electrolytic solution comprising a lithium salt, an organic solvent and a compound represented by Formula (I):
wherein R 1 is selected from the group consisting of a hydrogen atom, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C6-C30 aryl group, and a substituted or unsubstituted C8-C30 aralkenyl group;
R 2 represents a group of Formula II or III;
wherein R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are independently a hydrogen atom, a C1-C5 linear or branched alkyl group, or a C1-C5 linear or branched alkoxy group; and
X is an integer of 2 to 5.
13. The lithium-sulfur battery of claim 12 , wherein 0.1 to 20% by weight of the compound of said Formula (I) is included based on the weight of the electrolytic solution.
14. The lithium-sulfur battery of claim 12 , wherein the compound of said Formula (I) is bis(2-trimethylsiloxy-2-phenylethyl) trisulfide.
15. The lithium-sulfur battery of claim 12 , wherein the anode active material is at least one active material selected from the group consisting of elemental sulfur, Li 2 S n in which n≧1, a catholyte in which Li 2 S n , where n≧1, is dissolved, an organosulfur compound, and a carbon-sulfur polymer ((C 2 S x ) n ) where x=2.5 to 50, and n≧2.
16. The lithium-sulfur battery of claim 12 , wherein the cathode active material is selected from the group consisting of a lithium metal, a lithium alloy and a composite of lithium/inert sulfur.
17. The lithium-sulfur battery of claim 12 , wherein the lithium salt is selected from the group consisting of LiPF 6 , LiSO 3 CF 3 , LiN(SO 2 CF 3 ) 2 , LiClO 4 , LiBF 4 , LiAsF 6 , LiC(CF 3 SO 2 ) 3 , LiN(C 2 F 5 SO 2 ) 2 , LiN(CR 3 SO 2 ) 2 and a combination thereof.
18. The lithium-sulfur battery of claim 12 , wherein the organic solvent is selected from the group consisting of an oligoether-based compound, an ester carbonate-based compound, an alkyl ester-based compound, an aromatic nitrile-based compound, an amide-based compound, a lactone-based compound, a sulfur-based compound, and a combination thereof.
19. The lithium-sulfur battery of claim 18 , wherein the organic solvent is selected from the group consisting of tetrahydrofuran, 2-methyl tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylethyl carbonate, methylpropyl carbonate, methyl formate, methyl acetate, methyl propionate, butyl lactone, and a combination thereof.
20. The lithium-sulfur battery of claim 12 , wherein the organic electrolytic solution further comprises an electron conducting material.
21. The lithium-sulfur battery of claim 20 , wherein the electron conducting material is selected from the group consisting of a carbon black, a graphite, a carbon fiber, an electron conducting compound having at least one of a conjugate carbon-carbon double bond and a carbon-nitrogen double bond, and mixtures thereof.
22. A lithium-sulfur battery, comprising:
an anode comprising at least one anode active material selected from the group consisting of elemental sulfur, Li 2 S n where n≧1, a catholyte in which Li 2 S n , where n≧1, is dissolved, an organosulfur compound, a carbon-sulfur polymer represented by Formula (C 2 S x ) n where x=2.5 to 50 and n≧2, a sulfur-based compound, and a combination thereof;
a cathode comprising at least one cathode active material selected from the group consisting of a lithium metal, a lithium alloy and a composite of lithium/inert sulfur;
a separator interposed between the cathode and the anode to separate from each other; and
an electrolytic solution comprising:
a lithium salt;
an organic solvent;
a compound represented by Formula (I) in a percentage by weight from 0.1 to 20% based on the weight of the electrolyte solution:
wherein R 1 is selected from the group consisting of a hydrogen atom, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C6-C30 aryl group, and a substituted or unsubstituted C8-C30 aralkenyl group;
R 2 represents a group of Formula II or III;
wherein R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are independently a hydrogen atom, a C1-C5 linear or branched alkyl group, or a C1-C5 linear or branched alkoxy group;
X is an integer of 2 to 5; and
optionally an electron conducting material.