TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The content of phenyl carbonate compound (1) in component (A) is 0.001-10 weight%.The component (B) further contains cyclic carbonate having ethylenic unsaturated bond, cyclic carbonate having fluorine, mono-fluorophosphate, and/or difluoro phosphate.The content of cyclic carbonate having ethylenic unsaturated bond, cyclic carbonate having fluorine, mono-fluorophosphate, and/or difluoro phosphate in components (A) and (B) is 0.001-10 weight%, each.The content of phenyl carbonate compound (2) in component (B) is 0.001-10 weight%.The total content of phosphoric-acid ester compounds and carboxylate ester compound in the component (D) is 0.001-10 weight%.The non-aqueous electrolyte solution contains methylphenyl carbonate and vinylene carbonate, diphenyl carbonate and vinylene carbonate, or tris-(4-t-butylphenyl) phosphate and vinylene carbonate.The content of the diphenyl carbonate in non-aqueous electrolyte solution is 0.001-5 weight%. The content of vinylene carbonate is 0.001-20 weight%.The content of ethylene carbonate with respect to the total amount of ethylene carbonate and dialkyl carbonate is 5 to 50 volume%.Preferred Components: The cyclic carbonate is chosen from ethylene carbonate, propylene carbonate, asymmetrical chain-shaped dialkyl carbonate, and symmetrical chain-shaped dialkyl carbonate. SPECIFIC COMPOUNDS - 62 phenyl carbonate compounds (1) are disclosed e.g. methylphenyl carbonate of formula (1a), ethylphenyl carbonate, n-propyl phenyl carbonate, i-propyl phenyl carbonate and n-butylphenyl carbonate. 148 phenyl carbonate compounds (2) are disclosed e.g. (2-t-butylphenyl)methyl carbonate of formula (1b), (2-t-butylphenyl)ethyl carbonate, (2-t-butylphenyl) n-propyl carbonate, (2-t-butylphenyl)i-propyl carbonate and n-butyl(2-t-butylphenyl) carbonate.    EXAMPLE - Vinylene carbonate (in weight%) (2) and methylphenyl carbonate (1) were mixed with mixture of ethylene carbonate, ethylmethyl carbonate and dimethyl carbonate in capacitance ratio of 2:3:3, and lithium hexafluoro phosphate in dry argon atmosphere, to obtain non-aqueous electrolyte solution.