TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The lithium salt includes lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium boron tetraflouride (LiBF4), LiN(C2F5SO3)2, lithium nitride-containing compound (LiN(C2F5SO2)2, LiN(CF3SO2)2, or LiN(Cx'F2x'+1SO2)(Cy'F2y'+1SO2)), lithium antimony hexafluoride (LiSbF6), lithium triflate (LiCF3SO3), lithium fluoride-containing compound (LiC4F9SO3), lithium aluminum oxide (LiAlO4), lithium aluminum tetrachloride (LiAlCl4), lithium chloride (LiC) and/or lithium iodide (LiI). The positive electrode is made of a metal coated with an active material. The active material includes LixMn1-yMyA2, LixMn2O4-zXz, LixMn2-yMyM'zA4, LixCo1-yMyA2, LixCo1-yMyO2-zXz, LixNi1-yMyO2-zXz, LixNi1-yCoyO2-zXz, LixNi1-y-zCoyMzAa, LixNi1-y-zCoyMzO2-aXa, LixNi1-y-zMnyMzAa and/or LixNi1-y-zMnyMzO2-aXa. The negative electrode is made of metal coated with active material(s) of crystalline carbon, amorphous carbon, carbon composite, carbon fiber, lithium metal, lithium alloy or lithium composite.x', y'=positive integer;x=0.9-1.1;y=0-0.5;z=0-0.5;a=0-2;M, M'= Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, Zr, Mn, Cr, Fe, Sr, V or rare earth elements;A=O, F, S or P;andX=F, S or P.Preferred Composition: The concentration of the lithium salt in the electrolyte solution is 0.6-2 M.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The carbonate-based solvent is a mixture of cyclic carbonate-based organic solvent(s) of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate and/or 2,3-pentylene carbonate; and carbonate-based organic solvent(s) of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethylmethyl carbonate (EMC), methylpropyl carbonate (MPC) and ethylpropyl carbonate (EPC). The ester-based solvent includes methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, gamma -butyrolactone, gamma -valerolactone, gamma -caprolactone, delta -valerolactone, and/or epsilon -caprolactone. The ether-based solvent includes tetrahydrofuran, 2-methyltetrahydrofuran and/or dibutyl ether. The ketone-based solvent is polymethylvinylketone. The non-aqueous organic solvent includes an aromatic hydrocarbon-based compound of formula (3). The aromatic hydrocarbon-based compound is benzene, fluorobenzene, bromobenzene, chlorobenzene, toluene, xylene, mesitylene, fluorotoluene, difluorotoluene or trifluorotoluene.R=halo or 1-10C alkyl;andq=0-6.Preferred Composition: The vinyl ethylene carbonate-based compound and halogenated diphenyl ether compound are added in an amount of 0.1-5 pbw and 0.1-20 pbw, based on 100 pbw of the basic electrolyte solution, respectively. The cyclic carbonate-based organic solvent and the chain carbonate-based organic solvent are mixed in a volume ratio of 1:1-1:9. The aromatic hydrocarbon-based solvent and the carbonate-based solvent are mixed in a volume ratio of 1:1-1:30. EXAMPLE - Lithium cobalt oxide (LiCoO2) as positive active material, polyvinylidene fluoride (PVDF) as binder, and carbon as conductive agent were mixed in a weight ratio of 92:4 :4. The mixture was dispersed in N-methyl-2-pyrrolidone to prepare positive electrode slurry. The slurry was coated on an aluminum foil, followed by drying and compressing, to fabricate a positive electrode. Artificial graphite as negative active material, styrene-butadiene rubber as binder, and carboxymethyl cellulose as thickening agent were mixed in a weight ratio of 96:2:2. The mixture was dispersed in water to prepare negative electrode slurry. The slurry was coated on copper foil, followed by drying and compressing, to fabricate a negative electrode. A polyethylene (PE) film separator was interposed between the positive and negative electrodes, wound, pressed, and inserted into a cylindrical can. An electrolyte solution was added to the cylindrical can to produce a lithium secondary battery. The electrolyte solution was prepared by dissolving lithium hexafluorophosphate (LiPF6) in a mixed organic solvent of ethylene carbonate (EC), ethylmethyl carbonate (EMC) and dimethyl carbonate (DMC) in a volume ratio of 1:1:1 to prepare a basic electrolyte solution (concentration: 1.3 M) and adding vinyl ethylene carbonate and fluoroethylene carbonate to the basic electrolyte solution. The vinyl ethylene carbonate and fluoroethylene carbonate were added at respective 0.5 wt.% and 1 wt.%, with respect to the weight of the organic solvent.