NONAQUEOUS ELECTROLYTIC SECONDARY BATTERY

Secondary battery includes an electrode group having a positive electrode, a negative electrode containing a material which absorbs and releases lithium ions, and a separator between these electrodes, and a non-aqueous electrolyte impregnated in the electrode group which contains a non-aqueous solvent and a lithium salt dissolved in the solvent. The electrode group is housed in a material made from a sheet of thickness = 0.5mm which contains a resin layer. The non-aqueous solvent contains gamma -butyrolactone, ethylene carbonate, >= 1 vinylene carbonate of formula (I), and >= 1 vinyl ethylene carbonate of formula (II). [Image] R1-R2H or 1-4C alkyl; R3-R5H or 1-4C alkyl; R6-R8H, 1-4C alkyl or 2-7C alkenyl. The vinylene carbonate compound is 0.01-5 weight% based on the total of non-aqueous solvent, the vinyl ethylene carbonate is 0.01-5 weight% based on the total of non-aqueous solvent and their total is 0.02-6 weight% based on the total of non-aqueous solvent. The gamma -butyrolactone is >= 50vol% based on the total volume of non-aqueous solvent and ethylene carbonate is >= 10vol%. An independent claim is also included for is the non-aqueous electrolyte for a secondary battery.