| 摘要 |
PROBLEM TO BE SOLVED: To provide a flat type nonaqueous electrolyte secondary battery having excellent a long term reliability, increasing airtightness of a battery to suppress deterioration of battery characteristics due to moisture penetration from outside under a humid environment, and preventing liquid leakage due to peeling of a surface of a gasket. SOLUTION: A tetrafluoroethylene perfluoroalkyl vinylether copolymer (PFA) is used for a gasket of a flat type nonaqueous electrolyte secondary battery, wherein the copolymer has: a fluorine content of 70 mol% or more and 85 mol% or less; and an intensity ratio of a peak in a range of 288-296 eV in a binding energy to a peak in a range of 281-288 eV in a binding energy of 4:1 to 6:1 when XPS analysis is performed using carbon as a target. COPYRIGHT: (C)2011,JPO&INPIT |
