TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Salt: The electrolyte salt (II) is chosen from lithium hexafluorophosphate, lithium salt of trifluoromethyl sulfonate (LiN(SO2CF3)2) and lithium salt of trifluoroethyl sulfonate (LiN(SO2C2F5)2). Preferred Material: A lithium secondary battery formed using non-aqueous electrolyte solution comprises anode, cathode and separator. The anode contains anode active material chosen from cobalt type complex oxide, nickel series complex oxide, manganese system complex oxide, iron-type complex oxide, vanadium system complex oxide, and lithium cobalt, preferably nickel series complex oxide. The cathode contains cathode active material such as graphite.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The solvent contains fluorine-type solvent (A) (in volume%) (20-80), non-fluorine-type cyclic carbonate (B) (3-40), and non-fluorine-type chain ester and/or non-fluorine-type chain ether (C) (10-77) with respect to whole solvent. Preferred Compound: The fluorine-containing ether is of formula: Rf1ORf2 (A1). The fluorine-containing ester is of formula: Rf3COORf4 (A2). The fluorine-containing carbonate is of formula: Rf5OCOORf6 (A3). The non-fluorine-type chain ester is of formula: R1COOR2 (C1). The non-fluorine-type chain ether is of formula: R3OR4 or R3-O-R4-O-R5 (C2).Rf1=3-6C fluorine-containing alkyl;Rf2=2-6C fluorine-containing alkyl;Rf3-Rf6=1-2C fluorine-containing alkyl;R1=1-2C alkyl;R2=1-4C alkyl;andR3-R5=3-6C alkyl.The non-fluorine-type cyclic carbonate (B) is chosen from ethylene carbonate, propylene carbonate and vinylene carbonate. Preferred Solvent: The solvent further contains surfactant (D) (5 mass% or less) with respect to whole solvent. The surfactant contains fluorine-containing carboxylate salt of formula: RfaCOO-M+ (D1a) or RfbCOO-M+ (D1b), and/or fluorine-containing sulfonate of formula: RfaSO3-M+ (D2a), or RfbSO3-M+ (D2b).Rfa=4-20C fluorine-containing alkyl;M+=alkali-metal cation, or NHR'3+;R'=H or 1-3C alkyl;andRfb=4-20C fluorine-containing ether.