Lithium secondary battery

1. A lithium secondary battery comprising:

a positive electrode;

a negative electrode, wherein the negative electrode comprises a lithium metal or a lithium alloy; and

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

wherein the separator has a first surface and a second surface,

wherein the electrolyte comprises a gel polymer electrolyte and a liquid electrolyte,

wherein the gel polymer electrolyte is included between the negative electrode and the first surface of the separator,

wherein the gel polymer electrolyte comprises a polymer matrix impregnated with an electrolyte solution consisting of an ether-based solvent, a lithium salt, and an additive,

wherein the gel polymer electrolyte is present on the negative electrode;

wherein the liquid electrolyte is included between the positive electrode and the second surface of the separator, and

wherein the liquid electrolyte consists of a carbonate-based solvent, a lithium salt, and an additive.

2. The lithium secondary battery of claim 1 , wherein the ether-based solvent comprises at least one selected from the group consisting of dimethyl ether, diethyl ether, dibutyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, 1,3-dioxolane, 4-methyldioxolane, 1,4-dioxane, 3,5-dimethyl isoxazole, 2,5-dimethylfuran, furan, 2-methylfuran, tetrahydrofuran and 2-methyltetrahydrofuran.

3. The lithium secondary battery of claim 1 , wherein the polymer matrix comprises at least one selected from the group consisting of polyethylene oxide, polypropylene oxide, polyacrylonitrile, polyvinyl chloride, polyvinylidene fluoride, polymethyl methacrylate, poly(meth)acrylate, polysiloxane and polyphosphazene.

4. The lithium secondary battery of claim 1 , wherein the carbonate-based solvent comprises at least one selected from the group consisting of ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 2,3-pentylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, dipropyl carbonate, methylpropyl carbonate and ethylpropyl carbonate.

5. The lithium secondary battery of claim 1 , wherein the additive in the gel polymer electrolyte and the liquid electrolyte is independently selected from the group consisting of vinylene carbonate and vinyl ethylene carbonate.

6. The lithium secondary battery of claim 1 , wherein the lithium salt in the gel polymer electrolyte and the liquid electrolyte is independently selected from the group consisting of LiCl, LiBr, LiFSI, LiI, LiClO 4 , LiAlO 4 , LiBF 4 , LiB 10 Cl 10 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiAlCl 4 , CH 3 SO 3 Li, (CF 3 SO 2 ) 2 NLi, (C 2 F 5 SO 2 ) 2 NLi, LiC 4 F 9 SO 3 , chloroborane lithium, lower aliphatic carboxylic acid lithium, and lithium tetraphenylborate.

7. The lithium secondary battery of claim 6 , wherein the lithium salt is selected from the group consisting of lithium hexafluorophosphate (LiPF 6 ) and lithium bisfluorosulfonyl imide (LiFSI).

8. The lithium secondary battery of claim 6 , wherein the lithium salt in the liquid electrolyte is present in a concentration from 0.2 M to 2 M.

9. The lithium secondary battery of claim 6 , wherein the lithium salt in the liquid electrolyte is present in a concentration from 0.6 M to 2 M.

10. The lithium secondary battery of claim 6 , wherein the lithium salt in the liquid electrolyte is present in a concentration from 0.7 M to 1.7 M.

11. The lithium secondary battery of claim 1 , wherein the carbonate-based solvent is selected from the group consisting of ethylene carbonate, diethyl carbonate and dimethyl carbonate.

12. The lithium secondary battery of claim 11 , wherein the solvent comprises ethylene carbonate, diethyl carbonate and dimethyl carbonate, which are present in a 1:2:1 volume ratio.

13. The lithium secondary battery of claim 1 , wherein the ether-based solvent is selected from the group consisting of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether and 1,3-dioxolane.

14. A lithium secondary battery comprising:

a positive electrode;

a negative electrode;

a separator and an electrolyte interposed between the positive electrode and the negative electrode;

wherein the separator has a first surface and a second surface,

wherein the electrolyte comprises a gel polymer electrolyte and a liquid electrolyte,

wherein the gel polymer electrolyte is interposed between the negative electrode and the first surface of the separator;

wherein the liquid electrolyte is interposed between the positive electrode and the second surface of the separator;

wherein the gel polymer electrolyte comprises a polymer matrix impregnated with a solution consisting of (i) an ether-based solvent, (ii) a lithium salt, and (iii) an additive selected from the group consisting of vinylene carbonate and vinyl ethylene carbonate;

wherein the gel polymer electrolyte is present on the negative electrode;

wherein the liquid electrolyte consists of (i) a carbonate-based solvent, (ii) a lithium salt, and (iii) an additive selected from the group consisting of vinylene carbonate and vinyl ethylene carbonate; and

wherein the liquid electrolyte is present on the positive electrode.

15. The lithium secondary battery of claim 14 , wherein the ether-based solvent is selected from the group consisting of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether and 1,3-dioxolane.

16. The lithium secondary battery of claim 14 , wherein the carbonate-based solvent is selected from the group consisting of ethylene carbonate, diethyl carbonate and dimethyl carbonate.

17. The lithium secondary battery of claim 14 , wherein the lithium salt in the liquid electrolyte is selected from the group consisting of lithium hexafluorophosphate (LiPF 6 ) and lithium bisfluorosulfonyl imide (LiFSI).