TECHNOLOGY FOCUS - ELECTRONICS - Preferred Electrolyte: The non-aqueous electrolyte further contains a compound (c1) having a sulfonyl group in addition to the compound (I). The non-aqueous electrolyte further contains a sulfone compound having a sulfonyl group. The non-aqueous electrolyte contains (I) (0.005-10 mass.%); and further contains vinylene carbonate or its derivative. The non-aqueous electrolyte further contains as lithium salt at least one compound selected from LiPF6, LiBF4, LiAsF6, LiSbF6, LiClO4, LiAlCl4 and LiN(CnF2n+1SO2) (CmF2m+1SO2) (where n and m are natural numbers). Preferred Battery: The positive electrode active substance of the positive electrode contains a lithium-containing complex oxide that can occlude and discharge lithium. The lithium-containing complex oxide has a lithium-manganese complex oxide having a spinel structure. The negative electrode active substance of the negative electrode contains at least two substances selected from materials that can occlude and discharge lithium, lithium metal, metal materials that can form an alloy with lithium and oxide materials. The negative electrode active substance contains a carbon material (preferably graphite or amorphous carbon).    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: The compound (c1) having a sulfonyl group is of formula (II). The sulfone compound is of formula (III). The aprotic solvent contains at least two solvents selected from cyclic carbonate, linear chain carbonate, aliphatic carboxylic acid ester, gamma -lactone, cyclic ether, linear chain ether and their fluorine derivative.Q'=O, methylene or single bond;A1=optionally substituted 1-5C alkylene, carbonyl, sulfinyl, 1-5C polyfluoroalkylene, optionally substituted 1-5C fluoroalkylene, group formed by turning at least one of the C-C bonds of optionally substituted 1-5C alkylene to a C-O-C bond, group formed by turning at least one of the C-C bonds of a 1-5C polyfluoroalkylene to C-O-C bond or group formed by turning at least one of the C-C bonds of optionally substituted 1-5C fluoroalkylene to C-O-C bond;B1=optionally substituted 1-5C alkylene, 1-5C polyfluoroalkylene or optionally substituted 1-5C fluoroalkylene;n'=0-2;R1-R6=H, 1-12C alkyl, 3-6C cycloalkyl or 6-12C aryl. SPECIFIC COMPOUNDS - 16 Compounds are specified as (I) e.g. 6-vinyl-(1,5,2,4)dioxadithiepane 2,2,4,4-tetraoxide (IA); 6-allyl-(1,5,2,4)dioxadithiepane 2,2,4,4-tetraoxide; 6-but-3-enyl-(1,5,2,4)dioxadithiepane 2,2,4,4-tetraoxide; 6-(1-methylene-propyl)-(1,5,2,4)dioxadithiepane 2,2,4,4-tetraoxide; and 6-isopropenyl-(1,5,2,4)dioxadithiepane 2,2,4,4-tetraoxide.    EXAMPLE - Aluminum foil (20 mu m) was used as positive electrode collector and LiMn2O4 was employed as positive electrode active substance. A copper foil (10 mu m) was used as negative electrode collector and the negative electrode was prepared by depositing lithium metal as negative electrode active substance to a thickness of 20 mu m on the copper foil by evaporation. A mixture solvent of ethylene carbonate and diethyl carbonate (volume ratio: 30/70) was employed as solvent of electrolyte and LiN(C2F5SO2)2, fluorine-containing organic lithium salt, was dissolved in the mixture solvent as supporting electrolyte by 1 mol/l. Additionally, 6-vinyl-(1,5,2,4)dioxadithiepane 2,2,4,4-tetraoxide (IA) (1 wt.%) was added. Then, the negative electrode and the positive electrode were laid one on the other with a polyethylene separator interposed between them to form non-aqueous electrolyte secondary battery (test). A comparative secondary battery was prepared similarly except that the compound (IA) was not added. A charge-discharge cycle test was carried out. The % capacity retention ratio was 82.3/45.6 for test/comparative battery.