Non-Aqueous Electrolyte and Lithium Secondary Battery Including the Same
A non-aqueous electrolyte solution according to an embodiment of the present invention includes a non-aqueous organic solvent, a lithium salt and a phosphonate-based additive having a predetermined chemical structure. Surface damage and side reactions of the cathode active material can be suppressed by the phosphonate-based additive. According to an embodiment of the present invention, a lithium secondary battery including the non-aqueous electrolyte solution is provided.
1 . A non-aqueous electrolyte solution, comprising:
a non-aqueous organic solvent;
a lithium salt; and
a phosphonate-based additive represented by Chemical Formula 1:
wherein, in Chemical Formula 1, R 1 and R 2 are each independently a substituted or unsubstituted hydrocarbon having 3 to 10 carbon atoms and including a terminal alkynyl group.
2 . The non-aqueous electrolyte solution according to claim 1 , wherein the phosphonate-based additive is represented by Chemical Formula 1-1:
wherein, in Chemical Formula 1-1, R 3 and R 4 are each independently a substituted or unsubstituted C 1 -C 8 alkylene group.
3 . The non-aqueous electrolyte solution according to claim 2 , wherein a substituent is bonded to at least one carbon atom of the alkylene group, and the substituent includes a C1-C7 alkyl group, a C2-C7 alkenyl group, a C2-C7 alkynyl group, a C1-C7 alkoxy group, halogen, a cyano group (—CN), a hydroxy group (—OH) or a nitro group (—NO 2 ).
4 . The non-aqueous electrolyte solution according to claim 1 , wherein an amount of the phosphonate-based additive is from 0.1 wt % to 5 wt % based on a total weight of the non-aqueous electrolyte solution.
5 . The non-aqueous electrolyte solution according to claim 1 , wherein the non-aqueous organic solvent includes at least one selected from the group consisting of ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and diethyl carbonate (DEC).
6 . A lithium secondary battery, comprising:
a cathode including a lithium-transition metal oxide as a cathode active material;
an anode;
a separation layer interposed between the anode and the cathode; and
the non-aqueous electrolyte solution according to claim 1 .
7 . The lithium secondary battery according to claim 6 , wherein the lithium-transition metal oxide is represented by Chemical Formula 2 below:
Li 1+a Ni 1−(x+y) Co x M y O 2 [Chemical Formula 2]
wherein, in Chemical Formula 2, −0.05≤a≤0.15, 0.01≤x≤0.3, 0.01≤y≤0.3, and M includes at least one element selected from the group consisting of Mn, Mg, Sr, Ba, B, Al, Si, Ti, Zr or W.
8 . The lithium secondary battery according to claim 7 , wherein in Chemical Formula 2, 0.01≤x≤0.2, 0.01≤y≤0.2.