TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Material: The cathode contains carbonaceous material as active material.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: The compound having cyano group is of formula (3): NC-(X)n-CN.X=CH2, CFH, CF2, CHR, CFR, CR2, C=O, O, S, NH or NR;R=optionally substituted 5C or less hydrocarbon or cyano group;andn=1 or more.The compound of formula (3) is preferably succinonitrile, glutaronitrile, adiponitrile, pimelo nitrile, subelo nitrile, azela nitrile, sebako nitrile, 3,3'-oxydipropionitrile, 3,3'-thiodipropionitrile, 1,2,3-propane tricarbonitrile or 1,3,5-pentane tricarbonitrile, preferably pimelo nitrile, subelo nitrile, azela nitrile, sebako nitrile, 3,3'-oxydipropionitrile or 1,3,5-pentane tricarbonitrile. The compound having cyano group is contained in an amount of 0.001-10 wt.%. The electrolyte solution further contains cyclic carbonate having halogen atom, cyclic carbonate having carbon-carbon unsaturated bond, monofluorophosphoric acid salt or difluorophosphate, preferably 0.001-70 wt.% of cyclic carbonate having halogen atom. The cyclic carbonate having halogen atom is fluoroethylene carbonate, difluoroethylene carbonate, fluoropropylene carbonate, trifluoromethyl ethylene carbonate or fluoro trifluoromethyl ethylene carbonate. The cyclic carbonate having carbon-carbon unsaturated bond is contained in an amount of 0.001-10 wt.%, and is preferably vinylene carbonate, 4-methyl vinylene carbonate, 4,5-dimethylvinylene carbonate, 4-vinyl ethylene carbonate or 5-methyl-4-vinyl ethylene carbonate. The monofluoro phosphoric acid salt or difluorophosphate is contained in an amount of 0.001-5 wt.% of the ratio of the electrolyte solution. The electrolyte solution further contains cyano compound of formula (2): C(R4)(R5)=C(R6)(CN).R4-R6=H, cyano or optionally halogenated 1-10C hydrocarbon.R4 and R5 are not H simultaneously. SPECIFIC COMPOUNDS - The compound having cyano group is chosen from acrylonitrile, methacrylonitrile, crotononitrile, 3-methyl crotononitrile, 2-methyl-2-butene nitrile, 2-pentene nitrile, 2-methyl-2-pentene nitrile, 1-cyano-1-cyclopentene, 1-cyano-1-cyclohexene, geranitrile, cinnamonitrile, 2-furonitrile, fumaronitrile and tetracyanoethylene (all claimed).