Abstract: A nonaqueous electrolyte secondary battery includes: a separator including a polyolefin porous film; a porous layer containing a polyvinylidene fluoride-based resin; a positive electrode plate having a capacitance falling within a specific range; and a negative electrode plate having a capacitance falling within a specific range. The polyolefin porous film has a given piercing strength, having a value of not less than 0.00 and not more than 0.54, the value being represented by the following expression: |1?T/M|, where T and M are distances at which a critical load is reached in a scratch test in which the polyolefin porous film is moved in transverse and machine directions, respectively, under a constant load of 0.1N. The polyvinylidene fluoride-based resin contains an ?-form polyvinylidene fluoride-based resin in an amount of not less than 35.0 mol %.

Abstract: A nonaqueous electrolyte secondary battery including: 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 falling within a specific range; and a negative electrode plate having a capacitance falling within a specific range, wherein: the polyolefin porous film has a given rate of diminution of diethyl carbonate and a given spot diameter of the diethyl carbonate; the porous layer is provided between the nonaqueous electrolyte secondary battery separator and at least one of the positive electrode plate and the negative electrode plate; and the polyvinylidene fluoride-based resin contained in the porous layer contains an ?-form polyvinylidene fluoride-based resin in an amount of not less than 35.0 mol %.

Abstract: With a nonaqueous electrolyte secondary battery separator having a radical concentration of 5000×1012 spins/mg to 90000×1012 spins/mg, wherein the concentration is calculated from a peak at a g-value of not less than 2.010 in an electron spin resonance spectrum obtained through electron spin resonance analysis using a microwave having a frequency of 9.4 GHz, it is possible to provide a nonaqueous electrolyte secondary battery having a high battery resistance decreasing rate before and after battery formation.

Abstract: As a nonaqueous electrolyte secondary battery whose battery performance is prevented from being deteriorated by charge and discharge, provided is a nonaqueous electrolyte secondary battery including: a nonaqueous electrolyte secondary battery separator having ion permeability barrier energy of not less than 300 J/mol/?m and not more than 900 J/mol/?m per unit film thickness; and a nonaqueous electrolyte containing a given additive in an amount of not less than 0.5 ppm and not more than 300 ppm.

Abstract: A nonaqueous electrolyte secondary battery is provided in which a deterioration in charging capacity after high-rate discharge is inhibited. The nonaqueous electrolyte secondary battery includes (i) a nonaqueous electrolyte secondary battery separator including a polyolefin porous film which has a phase difference of not more than 80 nm with respect to light having a wavelength of 590 nm in a state where the polyolefin porous film is impregnated with ethanol and a porosity of 30% to 60% and (ii) a nonaqueous electrolyte containing a predetermined additive in an amount of not less than 0.5 ppm and not more than 300 ppm.

Abstract: A nonaqueous electrolyte secondary battery which can inhibit deterioration in charging capacity after high-rate discharge is provided. The nonaqueous electrolyte secondary battery includes (i) a nonaqueous electrolyte secondary battery separator including a polyolefin porous film whose peeling strength measured by a blocking test is not less than 0.2 N and puncture strength changes through the blocking test by not more than 15%, and (ii) a nonaqueous electrolyte containing a predetermined additive in an amount of not less than 0.5 ppm and not more than 300 ppm.

Abstract: A nonaqueous electrolyte secondary battery including: 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 falling within a specific range; and a negative electrode plate having a capacitance falling within a specific range, wherein: the polyolefin porous film has a given rate of diminution of diethyl carbonate and a given spot diameter of the diethyl carbonate; the porous layer is provided between the nonaqueous electrolyte secondary battery separator and at least one of the positive electrode plate and the negative electrode plate; and the polyvinylidene fluoride-based resin contained in the porous layer contains an ?-form polyvinylidene fluoride-based resin in an amount of not less than 35.0 mol %.

Abstract: A nonaqueous electrolyte secondary battery includes: a separator including a polyolefin porous film; a porous layer containing a polyvinylidene fluoride-based resin; a positive electrode plate having a capacitance falling within a specific range; and a negative electrode plate having a capacitance falling within a specific range. The polyolefin porous film has a given piercing strength, having a value of not less than 0.00 and not more than 0.54, the value being represented by the following expression: |1?T/M|, where T and M are distances at which a critical load is reached in a scratch test in which the polyolefin porous film is moved in transverse and machine directions, respectively, under a constant load of 0.1N. The polyvinylidene fluoride-based resin contains an ?-form polyvinylidene fluoride-based resin in an amount of not less than 35.0 mol %.

Abstract: With a nonaqueous electrolyte secondary battery separator having a radical concentration of 5000×1012 spins/mg to 90000×1012 spins/mg, wherein the concentration is calculated from a peak at a g-value of not less than 2.010 in an electron spin resonance spectrum obtained through electron spin resonance analysis using a microwave having a frequency of 9.4 GHz, it is possible to provide a nonaqueous electrolyte secondary battery having a high battery resistance decreasing rate before and after battery formation.

Abstract: As a nonaqueous electrolyte secondary battery whose battery performance is prevented from being deteriorated by charge and discharge, provided is a nonaqueous electrolyte secondary battery including: a nonaqueous electrolyte secondary battery separator having ion permeability barrier energy of not less than 300 J/mol/?m and not more than 900 J/mol/?m per unit film thickness; and a nonaqueous electrolyte containing a given additive in an amount of not less than 0.5 ppm and not more than 300 ppm.

Abstract: A nonaqueous electrolyte secondary battery which includes, as a nonaqueous electrolyte secondary battery separator or as a base material of a nonaqueous electrolyte secondary battery laminated separator, a porous film containing a polyolefin-based resin as a main component and containing phosphoric esters in an amount of not less than 5 ppm and not more than 700 ppm in terms of a mass ratio relative to total mass of the porous film is excellent in rate characteristic maintaining property.

Abstract: A method of producing a nonaqueous electrolyte secondary battery separator capable of realizing a nonaqueous electrolyte secondary battery having a higher rate-characteristic-maintenance property is provided. A porous film containing polyolefin as a main component is immersed in a polar solvent at no greater than 100° C.