ELECTROLYTE FOR LITHIUM SECONDARY BATTERY AND LITHIUM SECONDARY BATTERY INCLUDING THE SAME
An electrolyte for a lithium secondary battery according to exemplary embodiments may include an organic solvent, a lithium salt, and an additive including a polyalkylene glycol dialkyl ether compound having a weight average molecular weight in a specific range.
1 . An electrolyte for a lithium secondary battery comprising:
an organic solvent;
a lithium salt; and
an additive including a polyalkylene glycol dialkyl ether compound having a weight average molecular weight (Mw) of 1,000 to 20,000.
2 . The electrolyte for a lithium secondary battery according to claim 1 , wherein the number of carbon atoms of alkyl groups at both ends of the polyalkylene glycol dialkyl ether compound is each independently 1 to 4.
3 . The electrolyte for a lithium secondary battery according to claim 1 , wherein the polyalkylene glycol dialkyl ether compound includes a polyethylene glycol dialkyl ether compound.
4 . The electrolyte for a lithium secondary battery according to claim 1 , wherein the polyalkylene glycol dialkyl ether compound is represented by Formula 1 below:
(in Formula 1, R 1 and R 2 are each independently an alkyl group having 1 to 4 carbon atoms, R 3 is hydrogen or a methyl group, and n is 20 to 450).
5 . The electrolyte for a lithium secondary battery according to claim 1 , wherein the polyalkylene glycol dialkyl ether compound has a weight average molecular weight of 2,000 to 5,000.
6 . The electrolyte for a lithium secondary battery according to claim 1 , wherein the polyalkylene glycol dialkyl ether compound is included in an amount of 0.1 to 2.5% by weight based on a total weight of the electrolyte.
7 . The electrolyte for a lithium secondary battery according to claim 1 , wherein the polyalkylene glycol dialkyl ether compound includes polyethylene glycol dimethyl ether.
8 . The electrolyte for a lithium secondary battery according to claim 1 , wherein the organic solvent includes a linear carbonate solvent and a cyclic carbonate solvent.
9 . The electrolyte for a lithium secondary battery according to claim 1 , further comprising an auxiliary additive including at least one of a fluorine-containing cyclic carbonate compound, a sultone compound, a cyclic sulfate compound, and a fluorine-containing lithium phosphate compound.
10 . The electrolyte for a lithium secondary battery according to claim 9 , wherein the auxiliary additive comprises a fluorine-containing cyclic carbonate compound, an alkyl sultone compound, an alkenyl sultone compound, a cyclic sulfate compound, and a fluorine-containing lithium phosphate compound.
11 . The electrolyte for a lithium secondary battery according to claim 9 , wherein the auxiliary additive is included in an amount of 1 to 5% by weight based on the total weight of the electrolyte.
12 . The electrolyte for a lithium secondary battery according to claim 9 , wherein a ratio of the content of the auxiliary additive to the content of the polyalkylene glycol dialkyl ether compound is 1 to 5.
13 . A lithium secondary battery comprising:
a cathode;
an anode;
a separation membrane interposed between the cathode and the anode; and
the electrolyte for a lithium secondary battery according to claim 1 .
14 . The lithium secondary battery according to claim 13 , wherein the cathode includes a cathode active material including a lithium-transition metal oxide, and
the lithium-transition metal oxide includes 80 mol % or more of nickel based on the total number of moles of all elements except for lithium and oxygen.