Nonaqueous electrolyte secondary battery, and method for producing a nonaqueous electrolyte secondary battery

A method for producing a nonaqueous electrolyte secondary battery in which a wound electrode body and a nonaqueous electrolyte solution are accommodated in a case, the method comprising:

• a winding step of producing a wound electrode body by stacking a positive electrode and a negative electrode across a separator to produce a stack, followed by winding the stack;
• and
• a sealing step of accommodating the wound electrode body and the nonaqueous electrolyte solution in the case, followed by sealing the case,
• wherein the positive electrode has a foil-shaped positive electrode collector, and a positive electrode mix layer provided on a surface of the positive electrode collector;
• and
• the separator has a resin substrate layer containing an insulating resin, and a heat resistance layer formed on one face of the resin substrate layer;
• the peel strength of a boundary between the resin substrate layer and the heat resistance layer is set to 16 N/m or more and 155 N/m or less and the density of the positive electrode mix layer is set to 2.3 g/cc or more and 2.6 g/cc or less,
• the positive electrode, the negative electrode and the separator are stacked in such a manner that the heat resistance layer of the separator and the positive electrode mix layer of the positive electrode oppose each other,
• in the winding step, the stack is produced by nipping the positive electrode, the negative electrode and the separator between a pair of rollers, and the stack is supplied towards a winding axis, and
• the tension in the positive electrode and the negative electrode during winding of the stack is set to be higher than the tension in the separator, the tension in the positive electrode and the negative electrode is adjusted to be in a range of 2.5 N to 12.0 N, and the tension in the separator is adjusted to be in a range of 1.0 N to 6.0 N.