Patent ID: 10720664

Abstract:
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): Rf1—O—Rf2  (1) wherein Rf1 and Rf2 are the same as or different from each other, each being a C1-10 alkyl group or a C1-10 fluoroalkyl group; and at least one of Rf1 and Rf2 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): Rf1OH  (2) wherein Rf1 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.