Nonaqueous electrolyte secondary battery

A nonaqueous electrolyte secondary battery comprising:

• a nonaqueous electrolyte secondary battery separator including a polyolefin porous film;
• a porous layer containing a polyvinylidene fluoride-based resin;
• a positive electrode plate having a capacitance of not less than 1 nF and not more than 1000 nF per measurement area of 900 mm2;
• and
• a negative electrode plate having a capacitance of not less than 4 nF and not more than 8500 nF per measurement area of 900 mm2,
• the polyolefin porous film having a parameter X of not more than 20, the parameter X being calculated in accordance with the following expression:
• X=100×|MD tan δ−TD tan δ|/{(MD tan δ+TD tan δ)/2}
• where MD tan δ represents a tan δ in a machine direction and TD tan δ represents a tan δ in a transverse direction, the tan δ in the machine direction and the tan δ in the transverse direction each being obtained through a viscoelasticity measurement performed at a frequency of 10 Hz and at a temperature of 90° C.,
• the porous layer being provided between the nonaqueous electrolyte secondary battery separator and at least one of the positive electrode plate and the negative electrode plate,
• the polyvinylidene fluoride-based resin contained in the porous layer containing an α-form polyvinylidene fluoride-based resin and a β-form polyvinylidene fluoride-based resin,
• a content of the α-form polyvinylidene fluoride-based resin being not less than 35.0 mol % with respect to 100 mol % of a total content of the α-form polyvinylidene fluoride-based resin and the β-form polyvinylidene fluoride-based resin in the polyvinylidene fluoride-based resin,
• the content of the α-form polyvinylidene fluoride-based resin being calculated by (a) waveform separation of (α/2) observed at around −78 ppm in a 19F-NMR spectrum obtained from the porous layer and (b) waveform separation of {(α/2)+β} observed at around −95 ppm in the 19F-NMR spectrum obtained from the porous layer.