TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Electrolyte: The electrolyte comprises (wt.%) the dicarboxylic acid anhydride/optionally substituted diglycolic acid anhydride (0.1 - 2); and halogenated ethylene carbonate (0.1 - 10). Preferred Battery: The positive electrode active material is lithium compounds selected from LixMn1-yMyA2, LixMn1-yMyO2-zXz, LixMn2O4-zXz, LixMn2-yMyM'2A4, LixCo1-yMyA2, LixCo1-yMyO2-zXz, LixNi1-yMyA2, LixNi1-yMyO2-zXz, LixNi1-yCoyO2-zXz, LixNi1-y-zCoyMzAt, LixNi1-y-zCoyMzO2-tXt, LixNi1-y-zMnyMzAt, and LixNi1-y-zMnyMzO2-tXt. The negative electrode active material is selected from crystalline carbon, amorphous carbon, a carbon composite, carbon fiber, a lithium metal, and a lithium alloy. The lithium secondary battery is a cylindrical type or a polygon type.x=0.9 - 1.1;y and z=0 - 0.5;t=0 - 2;M and M'=Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, Zr, Mn, Cr, Fe, Sr, V or rare earth element;A=O, F, S or P;andX=F, S or P.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The lithium salt is at least one or two selected from LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiN(SO3CF3)2, LiC4F9SO3, LiAlO4, LiAlCl4, LiCl, and LiI.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The dicarboxylic acid anhydride is succinic acid anhydride, maleic acid anhydride, glutaric acid anhydride or itaconic acid anhydride. The diglycolic acid anhydride is mono-substituted by 1-10C alkyl, alkene, acyl or halo. The halogenated ethylene carbonate is (1,3)dioxolan-2-one of formula (I) (preferably fluoroethylene carbonate). The non-aqueous organic solvent is carbonate, ester, ether or ketone. The carbonate is a mixture of a cyclic carbonate and a chain carbonate. The cyclic carbonate is ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, or 2,3-pentylene carbonate. The chain carbonate is dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylmethyl carbonate or ethylpropyl carbonate. The non-aqueous organic solvent is a mixture of a carbonate-based solvent and an aromatic hydrocarbon-based organic solvent. The aromatic hydrocarbon-based organic solvent is phenyl (optionally mono- - hexa-substituted by halo or 1-10C alkyl) (preferably benzene, fluorobenzene, chlorobenzene, bromobenzene, toluene, xylene and/or mesitylene). The carbonate-based solvent and the aromatic hydrocarbon-based organic solvent are mixed with each other in a volumetric ratio of 1:1 - 30:1.X=halo;Y=H or halo;andn and m=1 or 2. EXAMPLE - LiCoO2 as a positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, and carbon as a conductive agent were mixed in a ratio of 92:4:4 and then, the resultant mixture was dispersed into N-methyl-2-pyrrolidone to manufacture positive electrode slurry. An Al foil having a thickness of 20 microns was coated with the slurry and then, was dried and rolled to manufacture a positive electrode. Artificial graphite as a negative electrode active material, styrene-butadiene rubber as a binder, and carboxymethylcellulose as a thickener were mixed with each other in a ratio of 96:2:2 and then, the resultant mixture was dispersed into water to manufacture a negative electrode active material slurry. A Cu foil having a thickness of 15 microns was coated with the slurry and then, was dried and rolled to manufacture a negative electrode. A film separator formed of polyethylene (PE) to have a thickness of 20 microns was interposed between the manufactured electrodes and then, the electrodes with the film separator interposed were wound and compressed to be inserted into a cylinder type can. An electrolyte was injected into the cylinder type can to manufacture a lithium secondary battery. LiPF6 of 1.3M was dissolved in an ethylene carbonate/ethylmethyl carbonate/dimethyl carbonate mixed solvent (in a volumetric ratio of 1:1:1) and then, succinic acid anhydride and fluoroethylene carbonate were added to the resultant solution to manufacture the electrolyte (test). At this time, the amount of the succinic acid anhydride was 0.5 wt.% and the amount of the fluoroethylene carbonate was 1 wt.%. A comparative electrolyte was similarly prepared using succinic acid anhydride (3 wt.%). The batteries were tested for standard capacity, which was found to be 100/96% for test/comparative respectively. The discharge capacity recovery ration (%) (for test/comparative) was 75/20 (after preservation at 0degreesC for 4 hours) and 96/70 (after preservation at 85degreesC for 24 hours).