NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide means for increasing the capacity while suppressing the worsening the secondary battery cycle characteristics.SOLUTION: A secondary battery 1 comprises a power-generating element 4 which includes: a positive electrode plate 41 having a pair of positive electrode active material layers 41b and 41c; a negative electrode plate 42 having a pair of negative electrode active material layers 42b and 42c; and a separator 43 through which the positive and negative electrode plates are opposed to each other. In the secondary battery 1, the principal plane of active material layers are small in area, and shaped in a rectangular form having a short-side length of 132 mm or more. One of the pair positive electrode active material layers 41b and 41c and the pair of negative electrode active material layers 42b and 42c includes polyvinylidene fluoride. The secondary battery is arranged so that in a DSC curve obtained according to the differential scanning calorimetry on the active material layers including polyvinylidene fluoride, a heat absorption peak of the polyvinylidene fluoride which would arise in a range of 120-160°C arises in a temperature region of 140°C or higher.