Patent ID: 7402260

Claim:
A non-aqueous mixture solvent for a non-aqueous electrolytic solution to be used for electrochemical energy devices, which contains an aprotic solvent selected from the group consisting of ethylene carbonate, propylene carbonate, butylene, carbonate acid ester represented by a general formula R 1 OCOOR 2 (wherein R 1 and R 2 each represents same or different alkyl group having 1 to 4 carbon atoms), γ-butylolactone, 1,2-dimethoxyethane, diglyme, triglyme, tetraglyme, tetrahydrofuran, alkyl substituted tetrahydrofuran, 1,3-dioxolane, and alkyl substituted 1,3-dioxolane, and a fluorinated ketone of the formula: wherein R f 1 and R f 2 each independently represents a fluorinated aliphatic group, or R f 1 and R f 2 together form a cyclic group, Q represents a fluorinated or non-fluorinated alkylene group or a bond, and n represents 0 or 1.