LITHIUM ION SECONDARY BATTERY AND NONAQUEOUS ELECTROLYTE FOR LITHIUM ION SECONDARY BATTERY

The present invention provides a lithium ion secondary cell excellent in high-temperature storage characteristics and high voltage cycle characteristics; and a nonaqueous electrolyte for the cell. The present invention relates to a lithium ion secondary cell, comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte containing nonaqueous solvents and an electrolyte salt, the nonaqueous solvents comprising a fluorine-containing ether represented by the formula (1): Rf 1 -O-Rf 2 (1) wherein Rf 1 and Rf 2 are the same as or different from each other, each being a C 1-10 alkyl group or a C 1-10 fluoroalkyl group; and at least one of Rf 1 and Rf 2 is a fluoroalkyl group, and the following compounds (I) and (II): (I) a fluorine-containing unsaturated compound; and (II) a hydroxy group-containing compound represented by the formula (2): Rf 1 OH(2) wherein Rf 1 is the same as above, and the nonaqueous solvents comprising the compounds (I) and (II) in a total amount of 5000 ppm or less for the fluorine-containing ether.