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

1. An electrolyte for a lithium secondary battery, the electrolyte comprising:

an organic ester compound;

an organic solvent; and

a lithium salt:

wherein the organic ester compound comprises 3-(butyryloxy)propane-1,2-diyl diacetate, 3-(pentanoyloxy)propane-1,2-diyl diacetate, 3-(isobutyryloxy)propane-1,2-diyl diacetate, 3-((2-methylbutanoyl)oxy) propane-1,2-diyl diacetate, 3-((3-methylbutanoyl)oxy)propane-1,2-diyl diacetate, 3-acetoxypropane-1,2-diyl dipropionate, 3-(butyryloxy)propane-1,2-diyl dipropionate, 3-(isobutyryloxy)propane-1,2-diyl dipropionate, 3-((2-methylbutanoyl)oxy)propane-1,2-diyl dipropionate, 3-((3-methylbutanoyl)oxy)propane-1,2-diyl dipropionate, 3-acetoxy propane-1,2-diyl dibutyrate, 3-(propionyloxy)propane-1,2-diyl dibutyrate, 3-(pentanoyloxy)propane-1,2-diyl dibutyrate, 3-(isobutyryloxy)propane-1,2-diyl dibutyrate, 3-((2-methylbutanoyl)oxy)propane-1,2-diyl dibutyrate, 3-((3-methylbutanoyl)oxy)propane-1,2-diyl dibutyrate, 3-acetoxypropane-1,2-diyl dipentanoate, 3-(butyryloxy)propane-1,2-diyl dipentanoate, 3-(propionyloxy)propane-1,2-diyl dipentanoate, 3-(isobutyryloxy)propane-1,2-diyl dipentanoate, 3-((2-methylbutanoyl)oxy)propane-1,2-diyl dipentanoate, 3-((3-methylbutanoyl)oxy)propane-1,2-diyl dipentanoate, 2-(pentanoyloxy)propane-1,3-diyl diacetate, 2-(propionyloxy)propane-1,3-diyl diacetate, 2-(butyryloxy)propane-1,3-diyl diacetate, 2-(isobutyryloxy)propane-1,3-diyl diacetate, 2-((3-methylbutanoyl)oxy)propane-1,3-diyl diacetate, 2-((2-methylbutanoyl)oxy)propane-1,3-diyl diacetate, 2-acetoxypropane-1,3-diyl dipropionate, 2-(pentanoyloxy)propane-1,3-diyl dipropionate, 2-(butyryloxy)propane-1,3-diyl dipropionate, 2-(isobutyryloxy)propane-1,3-diyl dipropionate, 2-((3-methylbutanoyl)oxy)propane-1,3-diyl dipropionate, 2-((2-methylbutanoyl)oxy)propane-1,3-diyl dipropionate, 2-acetoxypropane-1,3-diyl dibutyrate, 2-(propionyloxy)propane-1,3-diyl dibutyrate, 2-(butyryloxy)propane-1,3-diyl dibutyrate, 2-(isobutyryloxy)propane-1,3-diyl dibutyrate, 2-((3-methylbutanoyl)oxy)propane-1,3-diyl dibutyrate, 2-((2-methylbutanoyl)oxy)propane-1,3-diyl dibutyrate, 2-acetoxypropane-1,3-diyl dipentanoate, 2-(propionyloxy)propane-1,3-diyl dipentanoate, 2-(butyryloxy)propane-1,3-diyl dipentanoate, 2-(isobutyryloxy)propane-1,3-diyl dipentanoate, 2-((3-methylbutanoyl)oxy)propane-1,3-diyl dipentanoate, 2-((2-methylbutanoyl)oxy)propane-1,3-diyl dipentanoate, or a combination thereof, and

wherein the amount of the organic ester compound is from about 10 percent by weight to about 70 percent by weight based on a total weight of the electrolyte.

2. The electrolyte of claim 1 , wherein the organic ester compound has a boiling point of about 150° C. or greater.

3. The electrolyte of claim 1 , wherein the amount of the organic ester compound is from about 12 percent by weight to about 45 percent by weight based on the total weight of the electrolyte.

4. The electrolyte of claim 1 , wherein an anion of the lithium salt comprises F − , Cl − , Br − , I − , NO 3 − , N(CN) 2 − , BF 4 − , ClO 4 − , PF 6 − , (CF 3 ) 2 PF 4 − , (CF 3 ) 3 PF 3 − , (CF 3 ) 4 PF 2 − , (CF 3 ) 5 PF − , (CF 3 ) 6 P − , CF 3 SO 3 − , CF 3 CF 2 SO 3 − , (CF 3 SO 2 ) 2 N − , (FSO 2 ) 2 N − , CF 3 CF 2 (CF 3 ) 2 CO − , (CF 3 SO 2 ) 2 CH − , (SF 5 ) 3 C − , (CF 3 SO 2 ) 3 C − , CF 3 (CF 2 ) 7 SO 3 − , CF 3 CO 2 − , CH 3 CO 2 − , SCN − , (CF 3 CF 2 SO 2 ) 2 N − , or a combination thereof.

5. The electrolyte of claim 1 , wherein the organic solvent comprises an ether solvent, an ester solvent, an amide solvent, a linear carbonate solvent, a cyclic carbonate solvent, or a combination thereof.

6. The electrolyte of claim 5 , wherein the ether solvent comprises dimethyl ether, diethyl ether, dipropyl ether, methylethyl ether, methyl propyl ether, ethyl propyl ether, or a combination thereof.

7. The electrolyte of claim 5 , wherein the ester solvent comprises methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, ε-caprolactone, or a combination thereof.

8. The electrolyte of claim 5 , wherein the amide solvent comprises N,N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, or a combination thereof.

9. The electrolyte of claim 5 , wherein the linear carbonate solvent comprises dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, a halide thereof, or a combination thereof.

10. The electrolyte of claim 5 , wherein the cyclic carbonate solvent comprises ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, a halide thereof, or a combination thereof.

11. The electrolyte of claim 1 , wherein the electrolyte further comprises an additive to form a solid electrolyte interface membrane, the additive comprising vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, a cyclic sulfite, a saturated sultone, an unsaturated sultone, an acyclic sulfone, or a combination thereof.

12. The electrolyte of claim 11 ,

wherein the cyclic sulfite is ethylene sulfite, methyl ethylene sulfite, ethyl ethylene sulfite, 4,5-dimethyl ethylene sulfite, 4,5-diethyl ethylene sulfite, propylene sulfite, 4,5-dimethyl propylene sulfite, 4,5-diethyl propylene sulfite, 4,6-dimethyl propylene sulfite, 4,6-diethyl propylene sulfite, 1,3-butylene glycol sulfite, or a combination thereof, and

wherein the acyclic sulfone is divinyl sulfone, dimethyl sulfone, diethyl sulfone, methylethyl sulfone, methylvinyl sulfone, or a combination thereof.

13. The electrolyte of claim 11 ,

wherein the saturated sultone is 1,3-propane sultone, 1,4-butane sultone, or a combination thereof, and

wherein the unsaturated sultone is ethene sultone, 1,3-propene sultone, 1,4-butene sultone, 1-methyl-1,3-propene sultone, or a combination thereof.

14. The electrolyte of claim 11 , wherein an amount of the additive to form a solid electrolyte interface membrane is from about 0.01 parts by weight to about 10 parts by weight based on a total weight of the electrolyte for a lithium secondary battery.

15. The electrolyte of claim 1 , wherein a concentration of the lithium salt may be from about 0.6 moles per liter to about 2.0 moles per liter.

16. A lithium secondary battery comprising:

a cathode;

an anode; and

the electrolyte according to claim 1 , disposed between the cathode and the anode.

17. The lithium secondary battery of claim 16 , further comprising a film disposed on a surface of the anode, wherein the film comprises the organic ester compound.