Electrolyte solution and lithium ion secondary battery using the same

摘要

The present invention provides an electrolyte solution and a lithium ion secondary battery which maintain for a long period high battery characteristics represented by the discharge capacity retention rate after the charge/discharge cycle, and simultaneously achieve also the high safety represented by the flame retardation. The present invention provides an electrolyte solution containing a nonaqueous solvent, an electrolyte, a specific compound having a perfluoroalkyl group in the molecule, and an additive having a fluorine atom and/or a phosphorus atom in the molecule.

主权项

1. An electrolyte solution comprising a nonaqueous solvent, an electrolyte, a compound represented by formula (1) and/or (2) shown below, and an additive having a fluorine atom and/or a phosphorus atom in the molecule:
Rf1-R1—X1-L1-R2  (1) Rf1-R1—X1-L1-R3-L2-X2—R4-Rf2  (2)wherein in the formula (1) and the formula (2),
each of Rf1 and Rf2 independently represents a perfluoroalkyl group having 2 to 20 carbon atoms; each of R1 and R4 independently represents a divalent saturated hydrocarbon group having 1 to 6 carbon atoms; each of X1 and X2 independently represents a divalent functional group selected from the group consisting of an ether group, a sulfide group, a sulfoxide group, a sulfone group, an ester group, a divalent amido group, and a divalent urethane group; each of L1 and L2 independently represents an oxycycloalkylene group which may be substituted with an alkyl group or a halogen atom, or a divalent oxyaromatic group which may be substituted with an alkyl group or a halogen atom; R2 represents an alkyl group having 1 to 20 carbon atoms which may be substituted with an alkyl group or a halogen atom (excluding a fluorine atom), a fluoroalkyl group which may be substituted with an alkyl group or a halogen atom (excluding a fluorine atom), an aryl group or a fluoroaryl group, or a monovalent group in which one or more of the alkyl, fluoroalkyl, aryl and fluoroaryl groups are bonded with one or more of divalent groups corresponding to the alkyl, fluoroalkyl, aryl, or fluoroaryl groups; and R3 represents a divalent saturated hydrocarbon group having 1 to 18 carbon atoms which may have one or more oxygen and/or sulfur atoms on the main chain and which may be substituted with an alkyl group.