Electrolyte for lithium secondary battery and lithium secondary battery including the same

1. A lithium secondary battery comprising a cathode comprising a spinel-structure lithium nickel manganese composite oxide represented by Formula 1 below as a cathode active material; an anode comprising a lithium metal oxide represented by Formula 2 below as an anode active material; and an electrolyte comprising a non-aqueous solvent and a lithium salt,

wherein the non-aqueous solvent consists of:

1 to 60 wt % of a cyclic carbonate based on a total weight of the non-aqueous solvent, and

40 to 99 wt % of a linear solvent based on a total weight of the non-aqueous solvent,

wherein the cyclic carbonate is FEC, and the linear solvent is DMC or MP,

Li x M y Mn 2−y O 4−z A z   (1)

Li a M′ b O 4−c A′ c   (2)

wherein, in Formula 1, 0.9≤x≤1.2, 0<y<2, and 0≤z<0.2;

M is at least one element selected from the group consisting of Al, Mg, Ni, Co, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Zr, Nb, Mo, Sr, Sb, W, Ti, and Bi; and

A is at least one monovalent or divalent anion,

wherein, in Formula 2, M′ is at least one element selected from the group consisting of Ti, Sn, Cu, Pb, Sb, Zn, Fe, In, Al, and Zr;

0.1≤a≤4 and 0.2≤b≤4, wherein a and b are determined according to oxidation number of M′;

0≤c<0.2, wherein c is determined according to oxidation number of A′; and

A′ is at least one monovalent or divalent anion.

2. The lithium secondary battery according to claim 1 , wherein the spinel-structure lithium nickel manganese composite oxide of Formula 1 is represented by Formula 3below:

Li x Ni y Mn 2−y O 4   (3)

wherein 0.9 ≤x≤1.2 and 0.4 ≤y≤0.5.

3. The lithium secondary battery according to claim 2 , wherein the spinel-structure lithium nickel manganese composite oxide of Formula 3 is LiNi 0.5 Mn 1.5 O 4 or LiNi 0.4 Mn 1.6 O 4 .

4. The lithium secondary battery according to claim 1 , wherein the lithium metal oxide of Formula 2 is a lithium metal oxide represented by Formula 4 below:

Li a Ti b O 4   (4)

wherein 0.5 ≤a≤3 and 1 ≤b≤2.5.

5. The lithium secondary battery according to claim 4 , wherein the lithium metal oxide of Formula 4 is Li 1.33 Ti 1.67 O 4 or LiTi 2 O 4 .

6. A battery module comprising the lithium secondary battery according to claim 1 as a unit cell.

7. A battery pack comprising the battery module according to claim 6 .

8. A device comprising the battery pack according to claim 7 .

9. The device according to claim 8 , wherein the device is an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a system for storing power.