TECHNOLOGY FOCUS - ELECTRONICS - Preferred Composition: The positive electrode contains lithium composite metal oxide and lithium-containing olivine-type phosphate as positive electrode active material. The negative electrode contains lithium metal, lithium alloy, lithium occulusive-releasable metallic compound and/or lithium occulusive-releasable carbon material as negative electrode active material.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The electrolytic salt is lithium salt chosen from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorophosphate and lithium (chelato)borate (LiB(-OC(=O)-C(=O)O-)2). The concentration of electrolytic salt is 0.5-2.5 M with respect to nonaqueous solvent.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The content of lithium (chelato)phosphate and content of unsaturated compound in nonaqueous electrolyte is 0.001-10 %mass and 0.001-10 %mass, respectively. The unsaturated compound is 2-propynyl methanesulfonate or 2-butyne-1,4-diyl dimethane sulfonate. The nonaqueous electrolyte further contains 0.001-0.4 M lithium difluorophosphate, and 0.001-10 %mass nitrile compound of formula: NC-L-CN. The nitrile compound is adiponitrile. The nonaqueous solvent contains cyclic carbonate and chain-shaped ester. The cyclic carbonate includes cyclic carbonate having unsaturated bond which is carbon-carbon double bond or carbon-carbon triple bond, and cyclic carbonate having fluorine atom. The cyclic carbonate having fluorine atom is chosen from 4-fluoro-1,3-dioxolan-2-one and trans-or cis-4,5-difluoro-1,3-dioxolan-2-one. The cyclic carbonate having unsaturated bond is chosen from vinylene carbonate, vinyl ethylene carbonate, 4-ethynyl-1,3-dioxolan-2-one, ethylene carbonate, propylene carbonate, 1,2-butylene carbonate and 2,3-butylene carbonate. The chain-shaped ester is chosen from asymmetrical linear carbonate chosen from methyl ethyl carbonate, methylpropyl carbonate, methyl isopropyl carbonate, methylbutyl carbonate, and ethylpropyl carbonate, symmetrical linear carbonate chosen from dimethyl carbonate, diethyl carbonate, dipropyl carbonate and dibutyl carbonate, and chain-shaped carboxylate ester chosen from ethyl acetate, pivalate, methyl propionate, ethylpropionate and methyl acetate.L=1-6C alkylene. Preferred Definitions:    R3=methyl;and    R1,R2=H.