NONAQUEOUS ELECTROLYTE SECONDARY BATTERY AND MANUFACTURING METHOD THEREFOR

An electrode group 1 which is formed by winding a positive electrode and a negative electrode into a flat shape with a separator interposed therebetween is contained in a rectangular battery case 4. The positive electrode has a tensile strength of 15 N/cm or lower when the positive electrode has a tensile extension of 1%, and the positive electrode has a tensile extension of 3% or higher when the positive electrode breaks. A gap S between a longitudinal end of the electrode group 1 and an inner surface of a short side of the rectangular battery case 4 meets the expression: S¥ 1/8 (L × ±) where L is a longitudinal length of the electrode group, and ± is a tensile extension of the positive electrode when the positive electrode breaks.