TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Electrolyte: The electrolyte optionally contains lithium hexafluoro phosphate and an anion of formula N(CnF2n+1SO2)2- (6).n = 1 or 2.Preferred Composition: The negative electrode of the battery contains graphite or lithium, carbon materials which inserts and extracts lithium, elementary substances, alloys and compounds of metallic elements and metalloid elements which form an alloy with lithium. The alloys and the compounds of the negative electrode contain one or more element group (A) consisting metallic elements and metalloid elements that form an alloy with lithium, and one or more element group (B) containing metallic elements and metalloid elements except for element group (A) and lithium. The positive electrode of the battery contains a metal oxide compound of formula LisMtOu (7).M = cobalt, nickel, manganese, iron, aluminum, vanadium, titanium and/or magnesium;s,t = 1 or more; andu = 2 or more.    TECHNOLOGY FOCUS - POLYMERS - Preferred Polymer: The secondary battery further contains a separator (23) made of a microporous film, located between positive electrode and negative electrode. The microporous film is made of mixture or copolymer of polyethylene and polypropylene or mixture of polyethylene and an aromatic polyamide. The microporous film has a two-layer structure of polyethylene and polypropylene or a three-layer structure of polypropylene, polyethylene and polypropylene. EXAMPLE - A secondary battery comprising a positive electrode, a negative electrode, a separator and an electrolyte was obtained. The positive electrode was obtained by fixing a positive electrode lead made of aluminum to one end of the positive electrode collector coated with lithium cobalt composite oxide powder, lithium carbonate powder, graphite and polyvinylidene fluoride. The negative electrode was obtained by fixing negative electrode lead made of nickel to one end of negative electrode collector containing graphite powder mixture. The separator was made of a microporous polypropylene film. The electrolyte was formed by dissolving (PF3(C2F5)3)- and PF6- in a molar ratio of 50, in a mixed solvent of ethylene carbonate and dimethyl carbonate. The secondary battery was discharged to a final voltage of 2.5 V at 1 A and subsequently to 4.2 V and 1 A for 5 hours and the battery was stored for 14 days at 55degreesC in the charged state. The battery was left at room temperature and was discharged to 2.5 V and 1 A. Then, one cycle of a charge and discharge was performed on the above conditions and the recovered capacity after storage was found to be 95%. The battery was charged again and discharged at 3 A and the battery had 83% of heavy load discharge maintenance rate.