TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The electrolytic salt is lithium salt or onium salt. The concentration of the electrolytic salt is 0.3-2.5 M with respect to nonaqueous solvent. The positive electrode contains a lithium composite metal oxide and/or a lithium-containing olivine-type phosphate, as a positive electrode active material. The negative electrode contains lithium metal, lithium alloy, carbon material capable of absorbing and desorbing lithium, and/or metal compound capable of absorbing and desorbing lithium, as a negative electrode active material. The electrolytic salt contains lithium hexafluorophosphate, lithium difluorophosphate, lithium monofluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethylsulfonyl)imide, lithium bistrifluoromethanesulfonimidate, lithium bis(fluorosulfonyl)imide, difluoro bis(oxalate-O,O') lithium phosphate and tetrafluoro (oxalate-O,O')lithium phosphate.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The content of the isocyanate compound (I) is 0.001-10 %mass. The isocyanate compound (I) is chosen from 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, 2-isocyanatoethyl crotonate, 2-(2-isocyanato ethoxy) ethylacrylate, 2-(2-isocyanato ethoxy)ethylmethacrylate, 2-(2-isocyanato ethoxy)ethyl crotonate and bis(2-isocyanatoethyl)carbonate. The nonaqueous solvent contains a cyclic carbonate and chain-shaped ester. The cyclic carbonate is cyclic carbonate having a unsaturated bond chosen from 4-ethynyl-1,3-dioxolan-2-one, vinylene carbonate and vinyl ethylene carbonate, and/or cyclic carbonate having a fluorine atom chosen from ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 4-fluoro-1,3-dioxolan-2-one, and trans or cis-4,5- difluoro-1,3-dioxolan-2-one. The cyclic carbonate has an unsaturated bond which is a carbon-carbon double bond or carbon-carbon triple bond, and a fluorine atom. The chain-shaped ester is asymmetrical linear carbonate chosen from methyl ethyl carbonate, methylpropyl carbonate, methyl isopropyl carbonate, methylbutyl carbonate, ethylpropyl carbonate and dimethyl carbonate, a symmetrical linear carbonate chosen from diethyl carbonate, dipropyl carbonate and dibutyl carbonate, and/or a chain-shaped carboxylate ester. The nonaqueous electrolyte is further contains nitrile compound and/or sultone compound.