NOVELTY - A non-aqueous lithium salt electrolyte, containing an organic alkali metal salt as additive, is new.    USE - Especially in lithium ion batteries for mobile applications, e.g. mobile telephones, camcorders and vehicles.    ADVANTAGE - The additive has a low volatility and a relatively high flame point, promotes lithium ion permeable cover layer formation on anodes and cathodes for passivating the electrodes and thus increasing the cycling capability and overcharge safety, has a very high thermal decomposition point and forms a vitreous polymeric layer on thermal decomposition e.g. caused by a short-circuit.    DETAILED DESCRIPTION - An electrolyte, consisting of a solution, in an aprotic solvent, of a lithium-containing inorganic or organic conductivity salt selected from methanides, triflates and imides, also contains an organic alkali metal salt additive.    INDEPENDENT CLAIMS are also included for the following:    (1) An electrochemical cell comprising a cathode, an anode, a separator and the above electrolyte.    (2) Use of organic alkali metal salts in electrochemical cells to improve the cycling capability of anodes and/or cathodes consisting of metallic lithium, graphite, graphitic carbon, carbon or other lithium intercalation or insertion compounds or alloy compounds by formation of a cover layer before lithium ion incorporation in the case of intercalation compounds or lithium deposition in the case of metallic anodes.    (3) Use of organic alkali metal salts in electrochemical cells to increase safety during overcharging by formation of a cover layer on a cathode consisting of Li(MnMez)2O4, Li(CoMez)O2, Li(CoNiMez)O2 or other lithium intercalation or insertion compound.    (4) Use of organic alkali metal salts in electrochemical cells to improve safety at high temperature by thermal decomposition of the additive to form a vitreous polymeric layer.    (5) Use of organic alkali metal salts as additives in electrochemical cells, batteries and secondary lithium batteries.    (6) Use of organic alkali metal salts as additives in combination with other lithium salts in secondary lithium batteries.    Preferred Features: The electrolyte contains 0.1-10 wt.% of the additive.