ELECTROLYTE FOR LITHIUM SECONDARY BATTERIES

The present invention relates to an electrolyte composition suitable for lithium secondary batteries, comprising a specific lithium salt, preferably lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), a fluorinated ether, preferably l,l,2,2-tetrafluoroethyl-2,2,3,3- tetrafluoropropyl ether (TTE), a cyclic sulfone, preferably sulfolane (SL), and a fluorinated carbonate, preferably fluoroethylene carbonate (FEC), in an amount (x) of 0 < x <= 15 voL%, wherein the cyclic sulfone/lithium salt is comprised in a molar ratio (y) of 1.0 <= y < = 5.0 and the fluorinated ether/lithium salt is comprised in a molar ratio (z) of 1.0 <= z <= 5.0. The electrolyte according to the invention results in improved electrochemical properties.