Lithium secondary battery
A lithium secondary battery including: a cathode including a high-voltage cathode active material; an anode; and an electrolyte disposed between the cathode and the anode, wherein the high-voltage cathode active material has a charge cut-off voltage of about 4.2 Volts or greater with respect to a lithium (Li) counter electrode, and wherein the electrolyte includes an organic fluorinated ether compound represented by Formula 1, an organic solvent, and a lithium salt: R 1 —O—CF n H 2-n —R 2 Formula 1 wherein, in Formula 1, R 1 is a C1-C10 alkyl group, a C3-C10 cycloalkyl group, a C1-C10 fluorinated alkyl group, or a C3-C10 fluorinated cycloalkyl group; R 2 is hydrogen, fluorine, a C1-C10 alkyl group, a C3-C10 cycloalkyl group, a C1-C10 fluorinated alkyl group, or a C3-C10 fluorinated cycloalkyl group; and n is 1 or 2.
1. A lithium secondary battery comprising:
a cathode including a cathode active material;
an anode; and
an electrolyte disposed between the cathode and the anode,
wherein the cathode active material has a charge cut-off voltage of about 4.2 Volts to about 10 Volts with respect to a lithium counter electrode, and
wherein the electrolyte comprises an organic fluorinated ether compound, an organic solvent, a lithium salt, and an additive to form a solid electrolyte interface membrane, wherein the organic fluorinated ether compound is represented by Formulae 2 to 14
Formula 2
R 11 —CF 2 —CH 2 —O—CFH—CFH—R 12
Formula 3
R 11 —CFH—CH 2 —O—CFH—CF 2 —R 12
Formula 4
R 11 —CF 2 —CH 2 —O—CFH—CF 2 —R 12
Formula 5
CF 3 —CH 2 —O—CFH—CFH—R 12
Formula 6
R 11 —CF 2 —CH 2 —O—CFH—CF 3
Formula 7
CF 3 —CH 2 —O—CFH—CF 2 —R 12
Formula 8
R 21 —CH 2 —O—CF 2 —CFH—R 12
Formula 9
R 21 —CH 2 —O—CF 2 —CF 2 —R 12
Formula 10
R 11 —CFH—CH 2 —O—CF 2 —R 22
Formula 11
R 11 —CF 2 —CH 2 —O—CF 2 —R 22
Formula 12
R 21 —CFH—O—CFH—R 22
Formula 13
R 21 —CFH—O—CF 2 —R 22
Formula 14
R 21 —CF 2 —O—CF 2 —R 22
wherein, in Formulae 2 to 7, 12, and 13,
R 11 is hydrogen, fluorine, a C1-C8 alkyl group, a C3-C8 cycloalkyl group, a C1-C8 fluorinated alkyl group, or a C3-C8 fluorinated cycloalkyl group;
R 21 is hydrogen, fluorine, a C1-C9 alkyl group, a C3-C9 cycloalkyl group, a C1-C9 fluorinated alkyl group, or a C3-C9 fluorinated cycloalkyl group;
R 12 is hydrogen, fluorine, a C1-C9 alkyl group, a C3-C9 cycloalkyl group, a C1-C9 fluorinated alkyl group, or a C3-C9 fluorinated cycloalkyl group; and
R 22 is hydrogen, fluorine, a C1-C10 alkyl group, a C3-C10 cycloalkyl group, a C1-C10 fluorinated alkyl group, or a C3-C10 fluorinated cycloalkyl group,
wherein in Formula 8,
R 21 is hydrogen, fluorine, a C1-C9 alkyl group, a C3-C9 cycloalkyl group, a C3-C9 fluorinated alkyl group, or a C3-C9 fluorinated cycloalkyl group; and
R 12 is hydrogen, a C1-C9 alkyl group, a C3-C9 cycloalkyl group, a C2-C9 fluorinated alkyl group, or a C3-C9 fluorinated cycloalkyl group;
wherein in Formula 9,
R 21 is fluorine, a C1-C9 alkyl group, a C3-C9 cycloalkyl group, a C1-C9 fluorinated alkyl group, or a C3-C9 fluorinated cycloalkyl group; and
R 12 is fluorine, a C1-C9 alkyl group, a C3-C9 cycloalkyl group, a C1-C9 fluorinated alkyl group, or a C3-C9 fluorinated cycloalkyl group;
wherein in Formula 10,
R 11 is hydrogen, a C1-C8 alkyl group, a C3-C8 cycloalkyl group, a C1-C8 fluorinated alkyl group, or a C3-C8 fluorinated cycloalkyl group; and
R 22 is hydrogen, fluorine, a C1-C10 alkyl group, a C3-C10 cycloalkyl group, a C1-C10 fluorinated alkyl group, or a C3-C10 fluorinated cycloalkyl group;
wherein in Formula 11,
R 11 is hydrogen, fluorine, a C1-C8 alkyl group, a C3-C8 cycloalkyl group, a C3-C8 fluorinated alkyl group, or a C3-C8 fluorinated cycloalkyl group; and
R 22 is hydrogen, a C1-C10 alkyl group, a C3-C10 cycloalkyl group, a C4-C10 fluorinated alkyl group, or a C3-C10 fluorinated cycloalkyl group; and
wherein in Formula 14,
R 21 is hydrogen, fluorine, a C1-C9 alkyl group, a C3-C9 cycloalkyl group, a C2-C9 fluorinated alkyl group, or a C3-C9 fluorinated cycloalkyl group; and
R 22 is hydrogen, fluorine, a C1-C10 alkyl group, a C3-C10 cycloalkyl group, a C3-C10 fluorinated alkyl group, or a C3-C10 fluorinated cycloalkyl group,
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, wherein an anion of the lithium salt is 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 CF 2 (CF 3 ) 2 CO − , (CF 3 SO 2 ) 2 N − , (FSO 2 ) 2 N − , (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, and
wherein the additive to form a solid electrolyte interface membrane is vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, a cyclic sulfite, a saturated sultone, an unsaturated sultone, an acyclic sulfone, or a combination thereof.
2. The lithium secondary battery of claim 1 , wherein the organic fluorinated ether compound has a boiling point of about 60° C. to about 200° C.
3. The lithium secondary battery of claim 1 , wherein the amount of the organic fluorinated ether compound is from about 5 percent by weight to about 70 percent by weight based on a total weight of the electrolyte.
4. The lithium secondary battery of claim 1 , wherein the cathode active material has a charge cut-off voltage of about 5.5 Volts to about 10 Volts, with respect to lithium (Li) counter electrode.
5. The lithium secondary battery of claim 1 , wherein the cathode active material comprises Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 .
6. 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.
7. The lithium secondary battery of claim 1 , further comprising a film disposed on a surface of the anode, wherein the film comprises an organic fluorinated ether compound represented by Formulae 2 to 14.