Liquid electrolyte additive for lithium secondary battery, non-aqueous liquid electrolyte and lithium secondary battery comprising the same

1. A non-aqueous liquid electrolyte comprising a non-aqueous organic solvent, a lithium salt and an additive,

wherein the additive comprises at least one isocyanate-based compound comprising a carbon-carbon triple bond, selected from the group consisting of compounds represented by the following Chemical Formulae 1 to 3:

wherein, in Chemical Formula 3, R is a linear or cyclic alkyl group, or an aromatic alkyl compound.

2. The non-aqueous liquid electrolyte of claim 1 , wherein R of the compound represented by Chemical Formula 3 is a hydrocarbon group excluding two isocyanate groups in one of compound selected from the group consisting of compounds represented by the following Chemical Formulae 4 to 7:

3. The non-aqueous liquid electrolyte of claim 1 , wherein the lithium salt comprises any one selected from the group consisting of LiPF 6 , LiAsF 6 , LiCF 3 SO 3 , LiN(FSO 2 ) 2 , LiN(CF 3 SO 2 ) 2 , LiBF 6 , LiSbF 6 , LiN(C 2 F 5 SO 2 ) 2 , LiAlO 4 , LiAlCl 4 , LiSO 3 CF 3 and LiClO 4 , or a mixture of two or more thereof.

4. The non-aqueous liquid electrolyte of claim 1 , wherein the non-aqueous organic solvent comprises a nitrile-based solvent, linear carbonate, cyclic carbonate, ester, ether, ketone, or a combination thereof.

5. The non-aqueous liquid electrolyte of claim 4 , wherein the cyclic carbonate is any one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC) and butylene carbonate (BC), or a mixture of two or more thereof, and the linear carbonate is any one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethylmethyl carbonate (EMC), methylpropyl carbonate (MPC) and ethylpropyl carbonate (EPC), or a mixture of two or more thereof.

6. The non-aqueous liquid electrolyte of claim 4 , wherein the nitrile-based solvent is one or more selected from the group consisting of acetonitrile, propionitrile, butyronitrile, valeronitrile, caprillonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile and 4-fluorophenylacetonitrile.

7. The non-aqueous liquid electrolyte of claim 1 , wherein the isocyanate-based compound comprising a carbon-carbon triple bond is comprised in 0.05% by weight to 2% by weight based on a total weight of the non-aqueous liquid electrolyte.

8. A lithium secondary battery comprising a negative electrode, a positive electrode, a separator and a non-aqueous liquid electrolyte,

wherein the non-aqueous liquid electrolyte is the non-aqueous liquid electrolyte of claim 1 and

an SEI film is formed on a surface of at least any one of the negative electrode or the positive electrode.

9. The lithium secondary battery of claim 8 , wherein the SEI film is formed through an urethane bond or electrostatic interaction of a hydroxyl group (R′—OH) on the surface of the negative electrode or the positive electrode, and nitrogen (N) of the isocyanate-based compound comprising a carbon-carbon triple bond of the non-aqueous liquid electrolyte, or formed through a reduction reaction of the carbon-carbon triple bond, a functional group of the isocyanate-based compound.

10. A lithium secondary battery comprising a negative electrode, a positive electrode, a separator and a non-aqueous liquid electrolyte,

wherein the non-aqueous liquid electrolyte is the non-aqueous liquid electrolyte of claim 1 , and

an SEI film is formed on a surface of at least any one of the negative electrode or the positive electrode.

11. A lithium secondary battery comprising a negative electrode, a positive electrode, a separator and a non-aqueous liquid electrolyte,

wherein the non-aqueous liquid electrolyte is the non-aqueous liquid electrolyte of claim 2 , and

an SEI film is formed on a surface of at least any one of the negative electrode or the positive electrode.

12. A lithium secondary battery comprising a negative electrode, a positive electrode, a separator and a non-aqueous liquid electrolyte,

wherein the non-aqueous liquid electrolyte is the non-aqueous liquid electrolyte of claim 3 , and

an SEI film is formed on a surface of at least any one of the negative electrode or the positive electrode.

13. A lithium secondary battery comprising a negative electrode, a positive electrode, a separator and a non-aqueous liquid electrolyte,

wherein the non-aqueous liquid electrolyte is the non-aqueous liquid electrolyte of claim 4 , and

an SEI film is formed on a surface of at least any one of the negative electrode or the positive electrode.

14. A lithium secondary battery comprising a negative electrode, a positive electrode, a separator and a non-aqueous liquid electrolyte,

wherein the non-aqueous liquid electrolyte is the non-aqueous liquid electrolyte of claim 6 , and

an SEI film is formed on a surface of at least any one of the negative electrode or the positive electrode.

15. A lithium secondary battery comprising a negative electrode, a positive electrode, a separator and a non-aqueous liquid electrolyte,

wherein the non-aqueous liquid electrolyte is the non-aqueous liquid electrolyte of claim 6 , and

an SEI film is formed on a surface of at least any one of the negative electrode or the positive electrode.

16. A lithium secondary battery comprising a negative electrode, a positive electrode, a separator and a non-aqueous liquid electrolyte,

wherein the non-aqueous liquid electrolyte is the non-aqueous liquid electrolyte of claim 7 , and

an SEI film is formed on a surface of at least any one of the negative electrode or the positive electrode.