TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compounds: The compound having cyano groups is of formula: NC-A-CN.A=H, carbon, nitrogen, oxygen, sulfur, phosphorus, or 1-10C organic group containing halo.The content of compound having cyano groups and compound having isocyanate groups is 0.001-10 %mass. The compound having isocyanate groups is hexamethylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane-4,4'-diisocyanate, bicyclo(2.2.1)heptane-2,5-diylbis(methyl isocyanate), bicyclo(2.2.1)heptane-2,6-diylbis(methyl isocyanate), isophorone diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and/or polyisocyanate compound derived from the above compounds. The compound having cyano groups is glutaronitrile, adiponitrile, pimelonitrile and/or suberonitrile. The nonaqueous electrolyte solution further comprises cyclic carbonate having fluorine atom, cyclic carbonate having carbon-carbon unsaturated bond, monofluorophosphate, and/or difluorophosphate. The cyclic carbonate having fluorine atom is monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and/or 4,5-difluoroethylene carbonate. The cyclic carbonate having carbon-carbon unsaturated bond is vinylene carbonate, vinyl ethylene carbonate, and/or ethynyl ethylene carbonate. The nonaqueous electrolyte solution comprises 0.01-50 %mass of lithium compound of formula: LiN(ClF2l+1SO2)(CmF2m+1SO2) or LiCnF2n+1SO3, silicon-containing compound of formula: (R1-)e-M3-O-Si(-R2)(-R4)-R3, and/or alkyne compound of formula: R5-CC-R6, and 0.01-5 %mass of triazatriphosphinine derivative of formula (I).l,m,n=0-4;M3=metal atom, phosphorus atom, boron atom, or P=O;R1=1-11C alkyloxy, silyloxy, or 1-11C alkylsilyloxy;R2-R4=1-11C alkyl, 1-11C alkenyl, 1-11C alkyloxy, or 6-11C aryl;R5-R6=H, halo, or optionally substituted organic group;andX1-X6=halo, alkyl, aryl, alkoxy or aryloxy.The electrolyte solution comprises 0.01-1.5 %mass of a metal oxalate of formula: (M1)a(M2(C2O4)bRc)d.M1=group 1 element, group 2 element, or Al;M2=group 13 element, transition metal, group 14 element, or group 15 element;R=halo, 1-11C alkyl, or 1-11C halo-substituted alkyl;a,b=positive integer;c=0 or positive integer;andd=1-3.