Electrolyte solution for lithium-sulfur battery and lithium-sulfur battery comprising same

1. A liquid electrolyte for a lithium-sulfur battery comprising:

a lithium salt; and

a non-aqueous solvent,

wherein the non-aqueous solvent includes

i) 1,3-dioxolane (DOL), included in 10% by volume to 40% by volume of a total weight of the non-aqueous solvent;

ii) glycol ether represented by the following Chemical Formula 1; and

iii) linear ether represented by the following Chemical Formula 2:

R 1 —O—(CH 2 CH 2 O) x —R 2   [Chemical Formula 1]

R 3 —O—(CH 2 CH 2 O) y —R 4   [Chemical Formula 2]

in Chemical Formulae 1 and 2,

R 1 to R 4 are the same as or different from each other, and each independently a C1 to C6 alkyl group, a C6 to C12 aryl group, or a C7 to C13 arylalkyl group;

x is an integer of 1 to 4;

y is an integer of 0 to 4; and

the ether of Chemical Formula 1 is different from the ether of Chemical Formula 2.

2. The liquid electrolyte for a lithium-sulfur battery of claim 1 , wherein the glycol ether is one type selected from the group consisting of 1,2-dimethoxyethane, ethylene glycol ethylmethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether.

3. The liquid electrolyte for a lithium-sulfur battery of claim 1 , wherein the linear ether is one type selected from the group consisting of ethylene glycol ethylmethyl ether, ethylene glycol diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether and diisobutyl ether ether.

4. The liquid electrolyte for a lithium-sulfur battery of claim 1 , wherein the glycol ether and the linear ether are included in a volume ratio of 1:3 to 3:1.

5. The liquid electrolyte for a lithium-sulfur battery of claim 1 , wherein the lithium salt includes one type selected from the group consisting of LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiC 4 BO 8 , LiAsF 6 , LiSbF 6 , LiAlCl 4 , CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2 ) 2 NLi, (C 2 F 5 SO 2 ) 2 NLi, (SO 2 F) 2 NLi, (CF 3 SO 2 ) 3 CLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenylborate, lithium imide and combinations thereof.

6. The liquid electrolyte for a lithium-sulfur battery of claim 1 , wherein the lithium salt is included in a concentration of 0.1 M to 4.0 M.

7. The liquid electrolyte for a lithium-sulfur battery of claim 1 , further comprising an additive having N—O bonds in a molecule.

8. The liquid electrolyte for a lithium-sulfur battery of claim 7 , wherein the additive is one or more types selected from the group consisting of lithium nitrate, potassium nitrate, cesium nitrate, barium nitrate, ammonium nitrate, lithium nitrite, potassium nitrite, cesium nitrite, ammonium nitrite, methyl nitrate, dialkyl imidazolium nitrate, guanidine nitrate, imidazolium nitrate, pyridinium nitrate, ethyl nitrite, propyl nitrite, butyl nitrite, pentyl nitrite, octyl nitrite, nitromethane, nitropropane, nitrobutane, nitrobenzene, dinitrobenzene, nitro pyridine, dinitropyridine, nitrotoluene, dinitrotoluene, pyridine N-oxide, alkylpyridine N-oxide and tetramethylpiperidinyloxyl.

9. The liquid electrolyte for a lithium-sulfur battery of claim 7 , wherein the additive is included in 0.01% by weight to 10% by weight with respect to 100% by weight of the liquid electrolyte.

10. A lithium-sulfur battery comprising the liquid electrolyte of claim 1 .

11. The liquid electrolyte for a lithium-sulfur battery of claim 1 ,

wherein the cyclic ether is 1,3-dioxolane (DOL);

wherein the glycol ether is selected from the group consisting of ethylene glycol ethylmethyl ether (EGEME), ethylene glycol diethyl ether (EGDEE), and 1,2-dimethoxyethane (DME); and

wherein the linear ether is selected from the group consisting of ethylene glycol ethylmethyl ether (EGEME), ethylene glycol diethyl ether (EGDEE), and 1,2-dimethoxyethane (DME), diisobutyl ether (DIBE), and dipropyl ether (DPE).

12. The liquid electrolyte for a lithium-sulfur battery of claim 11 , wherein the non-aqueous solvent is selected from the group consisting of:

DOL:DME:EGEME;

DOL:DME:DPE;

DOL:EGEME:EGDEE;

DOL:EGEME:DPE; and

DOL:EGEME:DIBE.

13. The liquid electrolyte for a lithium-sulfur battery of claim 11 , wherein the non-aqueous solvent is selected from the group consisting of:

DOL:DME:EGEME in a volume ratio of 1:1:1;

DOL:DME:DPE in a volume ratio of 1:1:1;

DOL:EGEME:EGDEE in a volume ratio of 1:1:1;

DOL:EGEME:DPE in a volume ratio of 1:1:1; and

DOL:EGEME:DIBE in a volume ratio of 1:1:1.

14. The liquid electrolyte for a lithium-sulfur battery of claim 11 , wherein the lithium salt is LiTFSI.

15. The liquid electrolyte for a lithium-sulfur battery of claim 11 , further comprising LiNO 3 as an additive.

16. A lithium-sulfur battery comprising the liquid electrolyte of claim 11 .