Abstract: The present invention provides a nonaqueous electrolyte secondary battery laminated separator which improves a long-term battery characteristic of a nonaqueous electrolyte secondary battery. According to the nonaqueous electrolyte secondary battery laminated separator in accordance with an aspect of the present invention, an absolute value of a difference between (i) a standard deviation of whiteness index in one outermost layer and (ii) a standard deviation of whiteness index of the other outermost layer is greater than 0.01 and is 0.60 or less, and a greater one of the two standard deviation values of whiteness index is 0.06 or more and 0.91 or less.

Abstract: The present invention provides a nonaqueous electrolyte secondary battery porous layer which improves a long-term battery characteristic of a nonaqueous electrolyte secondary battery. In the nonaqueous electrolyte secondary battery porous layer in accordance with an aspect of the present invention, a standard deviation of whiteness index defined in E313 of the American Standards Test Methods is 0.06 or more and 0.91 or less.

Abstract: The present invention provides a nonaqueous electrolyte secondary battery porous layer which improves an initial battery characteristic immediately after initial charge and discharge of a nonaqueous electrolyte secondary battery. In the nonaqueous electrolyte secondary battery porous layer in accordance with an aspect of the present invention, a standard deviation of bursting strength is 0.6 or more and 11.0 or less.

Abstract: An aspect of the present invention achieves a nonaqueous electrolyte secondary battery laminated separator which has excellent heat resistance and exhibits an excellent initial battery characteristic when used in a nonaqueous electrolyte secondary battery. A nonaqueous electrolyte secondary battery laminated separator in accordance with an aspect of the present invention includes: a polyolefin porous film; and a porous layer which (i) is disposed on at least one surface of the polyolefin porous film and (ii) includes a heat resistant filler, the porous layer having a surface which has cracks, a ratio of a total area of the cracks to a surface area of the porous layer being 0.15% to 10%.

Abstract: An aspect of the present invention achieves a nonaqueous electrolyte secondary battery laminated separator which has excellent heat resistance and exhibits an excellent initial battery characteristic when used in a nonaqueous electrolyte secondary battery. A nonaqueous electrolyte secondary battery laminated separator in accordance with an aspect of the present invention includes: a polyolefin porous film; and a porous layer which (i) is disposed on at least one surface of the polyolefin porous film and (ii) includes a heat resistant filler, the porous layer having a surface which has cracks, a ratio of a total area of the cracks to a surface area of the porous layer being 0.15% to 10%.

Abstract: The present invention provides a nonaqueous electrolyte secondary battery porous layer which improves an initial battery characteristic immediately after initial charge and discharge of a nonaqueous electrolyte secondary battery. In the nonaqueous electrolyte secondary battery porous layer in accordance with an aspect of the present invention, a standard deviation of bursting strength is 0.6 or more and 11.0 or less.

Abstract: The present invention provides a nonaqueous electrolyte secondary battery porous layer which improves a long-term battery characteristic of a nonaqueous electrolyte secondary battery. The nonaqueous electrolyte secondary battery porous layer in accordance with an aspect of the present invention has a bursting strength of 3.0 kPa or more and 22.0 kPa or less.

Abstract: The present invention provides a nonaqueous electrolyte secondary battery laminated separator which improves a long-term battery characteristic of a nonaqueous electrolyte secondary battery. According to the nonaqueous electrolyte secondary battery laminated separator in accordance with an aspect of the present invention, an absolute value of a difference between (i) a standard deviation of whiteness index in one outermost layer and (ii) a standard deviation of whiteness index of the other outermost layer is greater than 0.01 and is 0.60 or less, and a greater one of the two standard deviation values of whiteness index is 0.06 or more and 0.91 or less.

Abstract: The present invention provides a nonaqueous electrolyte secondary battery porous layer which improves a long-term battery characteristic of a nonaqueous electrolyte secondary battery. In the nonaqueous electrolyte secondary battery porous layer in accordance with an aspect of the present invention, a standard deviation of whiteness index defined in E313 of the American Standards Test Methods is 0.06 or more and 0.91 or less.

Abstract: The present invention provides a nonaqueous electrolyte secondary battery including a porous layer which includes an organic filler in which Na element, Al element, and/or K element are contained, a total amount of the Na element, the Al element, and the K element contained falling within a certain range. The nonaqueous electrolyte secondary battery porous layer allows the nonaqueous electrolyte secondary battery to have an excellent battery capacity recovery rate after storage at a constant-voltage charge at a high temperature.

Abstract: The present invention provides, as a nonaqueous electrolyte secondary battery porous layer in which an amount of electric current during initial charging at a high temperature is decreased, a nonaqueous electrolyte secondary battery porous layer which includes an organic filler, a mass reduction ratio of the organic filler during a temperature rise to 500° C. being not more than 55% by mass.

Abstract: The present invention provides a nonaqueous electrolyte secondary battery including a porous layer which includes an organic filler in which Na element, Al element, and/or K element are contained, a total amount of the Na element, the Al element, and the K element contained falling within a certain range. The nonaqueous electrolyte secondary battery porous layer allows the nonaqueous electrolyte secondary battery to have an excellent battery capacity recovery rate after storage at a constant-voltage charge at a high temperature.

Abstract: The present invention provides, as a nonaqueous electrolyte secondary battery porous layer which is suitable for production of a nonaqueous electrolyte secondary battery having excellent high-temperature constant-voltage charge preservability, a nonaqueous electrolyte secondary battery porous layer containing an organic filler in an amount of 87% by weight to 99.5% by weight, the organic filler being configured so that an inclination of a straight line on a TG chart, which connects a point at 150° C. and a point at a TG inflection point temperature, is not less than ?0.10% by mass/° C.