Patent ID: 6942949

Claim:
A rechargeable lithium electrochemical cell comprising: (a) a cathode; (b) an anode containing lithium storage materials; and (c) a liquid electrolyte comprising a lithium salt and one or more saturated aprotic organic solvents, wherein the electrolyte further comprises an additive in a proportion of 0.001% to 10% by volume of said solvents, which is an organic compound containing at least one unsaturated carbon-carbon bond activated with respect to oxidation by electron-pushing alkyl groups, and which can be oxidized at the cathode at a potential of more than 4.3 V vs. Li/Li + to form a passivation layer on the cathode in which said additive is selected from the group consisting of 1,5-hexadiene, cyclohexene, and 4-vinylcyclohexene.