Patent ID: 6951699

Claim:
A non-aqueous secondary battery comprising a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte containing lithium salt and having a flat shape, wherein when a pressure of 2.5 kg/cm 2 is applied to the direction of thickness of the separator, thickness A of the separator is not less than 0.02 mm and not more than 0.15 mm and a porosity of the separator is 40% or higher, and when the absolute value of a change rate of the thickness (mm) of the separator relative to the pressure (kg/cm 2 ) applied to the direction of thickness of the separator is defined as B (mm/(kg/cm 2 )), pressure F which renders B/A=1 is not less than 0.05 kg/cm 2 and not more than 1 kg/cm 2 .