Abstract: A prismatic nonaqueous electrolyte secondary battery of the invention includes a process whereby a cylindrical electrode roll is produced by spirally rolling negative electrode plates made of elongated sheet-like negative electrode substrates to which is applied a negative electrode mixture containing negative electrode active material, and positive electrode plates made of elongated sheet-like positive electrode substrates to which is applied a positive electrode mixture containing positive electrode active material, insulated from each other by separators; and then the cylindrical electrode roll is crushed to be formed into a flattened electrode roll; the process of crushing the cylindrical electrode roll to form a flattened electrode roll being controlled so that, in the flattened electrode roll the ratio of change in the separator gas permeability between the winding start and the winding end is 55% or less of the gas permeability at the winding start.

Abstract: A prismatic battery according to one embodiment of the present invention includes a flat electrode group 10 stacked or rolled by mutually positive and negative electrodes with a separator therebetween, a pressing plate 13A, a current collecting body 18A or 18B and a plurality of exposed sections 16, at least one end of the positive and negative electrodes substrates in a width direction being uncoated with a positive or negative electrode mixture. The pressing plate 13A is welded to the exposed sections 16. The pressing plate 13A includes opposing surfaces with a space therebetween provided by folding back a metal plate, and includes a slit 15 along a folded back section at least to one of the opposing surface's side. The exposed sections 16 are inserted into a gap of the pressing plate 13A, and the exposed sections 16 and the pressing plate 13A are welded by a high energy beam from a transverse direction through the slit 15.