Electrolyte and electrochemical device comprising the same

1. An electrolyte, comprising a fluorinated cyclic carbonate, a multi-nitrile compound having an ether bond, and a dinitrile compound; wherein the dinitrile compound comprises at least one selected from the group consisting of succinonitrile and adiponitrile; based on the total weight of the electrolyte, the weight percentage (C f ) of the fluorinated cyclic carbonate is greater than the weight percentage (C n ) of the multi-nitrile compound having the ether bond,

wherein based on the total weight of the electrolyte, C f is about 0.1 wt %-about 10 wt %, and C n is about 0.1 wt %-about 5 wt %, and

wherein the multi-nitrile compound having an ether bond is selected from at least one of the group consisting of 1,2,3-tris(2-cyanoethoxy)propane, 1,2,4-tris(2-cyanoethoxy)butane, 1,1,1-tris(cyanoethoxymethylene)ethane, 1,1,1-tris(cyanoethoxymethylene)propane, 3-methyl-1,3,5-tris(cyanoethoxy)pentane, 1,2,7-tris(cyanoethoxy)heptane, 1,2,6-tris(cyanoethoxy)hexane, and 1,2,5-tris(cyanoethoxy)pentane.

2. The electrolyte according to claim 1 , wherein the multi-nitrile compound having an ether bond comprises Compound 1A:

3. The electrolyte according to claim 1 , wherein the fluorinated cyclic carbonate is selected from a fluorinated cyclic carbonate having an alkylene group with 2-6 carbon atoms.

4. The electrolyte according to claim 1 , wherein the fluorinated cyclic carbonate is selected from at least one of the group consisting of fluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4-(fluoromethyl)-ethylene carbonate, 4-(difluoromethyl)-ethylene carbonate, 4-(trifluoromethyl)-ethylene carbonate, 4-(fluoromethyl)-4-fluoroethylene carbonate, 4-(fluoromethyl)-5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, and 4,4-difluoro-5,5-dimethylethylene carbonate.

5. The electrolyte according to claim 1 , wherein the electrolyte further comprises a fluoroether selected from compounds represented by General Formula [2], [3], [4] or [5]:

Rf1-O—Rf2  [2],

Rf1-O—R  [3],

Rf1-O—(R′—O) n —Rf2  [4],

Rf1-O—(R′—O) n —R  [5],

or a combination thereof,

where:

in Formulas [2], [3], [4], and [5], Rf1 and Rf2 are each independently a linear or branched C 1 to C 12 fluoroalkyl group having at least one hydrogen atom replaced by fluorine, R is a linear or branched C 1 to C 12 alkyl group, and R′ is a linear or branched C 1 to C 5 alkylene group, and n is an integer from 1 to 5.

6. The electrolyte according to claim 1 , wherein the electrolyte further comprises a cyclic phosphonic anhydride selected from compounds represented by General Formula [6]:

where:

R 5 , R 6 , and R 7 are each independently selected from hydrogen, an alkyl group having 1-20 carbon atoms, or an aryl group having 6-26 carbon atoms, and

R 5 , R 6 and R 7 are identical to or different from each other or any two of them are identical.

7. The electrolyte according to claim 1 , wherein the electrolyte further comprises at least one of a cyclic carbonate having a carbon-carbon double bond, a fluorinated chain carbonate, and a compound having a sulfur-oxygen double bond.

8. The electrolyte according to claim 1 , wherein the electrolyte further comprises at least one of a cyclic carbonate, a chain carbonate, a cyclic carboxylate, a chain carboxylate, a cyclic ether, a chain ether, a phosphorus-based organic solvent, a sulfur-containing organic solvent, and an aromatic fluorine-containing solvent.