NOVELTY - A lithium-ion electrochemical cell comprises anode having active material in electronically conductive contact with current collector; cathode having upper charging voltage of 3-5 volts with respect to a Li/Li+ reference electrode and having cathode current collector; protective, conductive coating on collector; cathode active material having lithium insertion transition metal oxide, phosphate or sulfate; ion-permeable membrane; and electrolyte solution in ionically conductive contact with anode and cathode and having additive, lithium compound, and aprotic polar-solvent and/or polymer.    USE - As lithium-ion electrochemical cell (claimed) in lithium and lithium-ion batteries.    ADVANTAGE - The cell exhibits long cycle life at high temperature. The cell has reduced corrosion and extended life thereby increasing its usefulness.    DETAILED DESCRIPTION - A lithium-ion electrochemical cell comprises an anode containing an anode active material in electronically conductive contact with an anode current collector; a cathode exhibiting an upper charging voltage of 3-5 volts with respect to a Li/Li+ reference electrode, where the cathode comprises a cathode current collector; a protective, conductive coating on the cathode current collector; and a cathode active material placed on the top of the protective, conductive coating, where the cathode active material comprises a lithium insertion transition metal oxide, phosphate, or sulfate; an ion-permeable membrane as a separator between the anode and cathode; and an electrolyte solution being in ionically conductive contact with the anode and cathode, where the electrolyte solution comprises an additive, a lithium compound, and at least one aprotic polar-solvent, a polymer or a mixture of at least one aprotic polar solvent and a polymer. The lithium compound is at a concentration of 0.1-3 molar, the lithium compound is of formula Rf1SO2X-(Li+)Y'Za (I). The additive provides corrosion protection of the cathode current collector and/or the anode current collector. The additive is selected from LiBOB, LiF, LiFOB, LiPF6, LiBF4, LiAsF6, LiClO4, and LiPFn(R'f)m.    Rf1=1-4C perfluoroalkyl optionally interrupted by an ether oxygen;    X=C or N;    a=0 or 1;    Z=electron-withdrawing groups selected from CN, SO2Rf2, SO2R, P(O)(OR)2, CO2R, P(O)R2, C(O)Rf3, C(O)R, cycloalkenyl groups formed with it or H;    R=1-6C alkyl optionally interrupted by an ether oxygen and optionally substituted with aryl;    Rf2 and Rf3=1-4C perfluoroalkyl optionally interrupted by ether oxygen;    Y'=electron-withdrawing groups selected from CN, SO2Rf2, SO2R, P(O)(OR)2, CO2R, P(O)R2, C(O)Rf3, C(O)R, cycloalkenyl groups formed with it or H or is SO2Rf6;    Rf6=-(Rf4SO2N-(Li+)SO2)mRf5;    m=0 or 1;    Rf4=-CnF2n optionally interrupted by an ether oxygen;    Rf5=-CnF2n+1, where Rf5 is optionally interrupted by at least one ether oxygen;    n=1-4;or    n+m=6;    R'f=CF3 or C2F5.    Provided that:    (1) when X is C then a is 1, and a is 0 when X is N; and when X is C, a is 1 then Y' and Z is electron-withdrawing groups selected from CN, SO2Rf2, SO2R, P(O)(OR)2, CO2R, P(O)R2, C(O)Rf3, C(O)R, cycloalkenyl groups formed with it or H;    (2) Y' and Z cannot both be H;    (3) when X is N and a is 0, Y' is an electron-withdrawing group SO2Rf6.