TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The electrolyte comprises 0.05-0.1 wt.% alkali metal salt including sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium trifluoromethanesulfonate, sodium hexafluoroarsenate (all preferred), potassium hexafluorophosphate, potassium perchlorate, potassium tetrafluoroborate, potassium trifluoromethanesulfonate and/or potassium hexafluoroarsenate. The lithium salt is lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonimide), lithium tetrafluoroborate, lithium flouroborate (LiBF6), lithium hexafluroantimonate, lithium bis(perfluoroethylsulfonylimide), lithium tetrachloroaluminate, lithium triflate and/or lithium perchlorate. The electrolyte solvent is linear carbonate, cyclic carbonate and/or ester. The cathode active material is manganese spinel active material and/or lithium metal oxide including lithium-cobalt oxide, lithium-manganese-based oxide, lithium-nickel-manganese-based oxide, lithium-manganese-cobalt oxide and/or lithium-nickel-manganese-cobalt oxide.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The electrolyte comprises 0.1-5 wt.% vinylidene carbonate-based compound. Preferred Components: The linear carbonate is dipropyl carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate and/or ethyl propyl carbonate. The cyclic carbonate is ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate and/or vinylene carbonate. The ester is methyl acetate, ethyl acetate, propyl acetate, ethyl propionate, methyl propionate, gamma -butyrolactone, gamma -valerolactone, gamma -caprolactone, sigma -valerolactone and/or epsilon -caprolactone. The vinylidene carbonate is vinylene carbonate compound (vinylene carbonate) and/or vinylene ethylene carbonate (vinylene ethylene carbonate). The negative electrode active material is carbon based, preferably graphite carbon. EXAMPLE - No suitable example given.