A non-aqueous mixture solvent for a non-aqueous electrolytic solution to be used for electrochemical energy devices, which contains an aprotic solvent, and a fluorinated ketone of the formula: ##STR00001## (wherein R.sub.f.sup.1 and R.sub.f.sup.2 each independently represents a fluorinated aliphatic group, or R.sub.f.sup.1 and R.sub.f.sup.2 together form a cyclic group, Q represents a fluorinated or non-fluorinated alkylene group or a bond, and n represents 0 or 1), and an electrolytic solution containing the mixture solvent.