Method for producing wound electrode assembly, apparatus for producing wound electrode assembly, and power storage device

An apparatus for producing a wound electrode assembly including a lamination sheet in a wound state, the lamination sheet including a band-like positive electrode sheet, a band-like negative electrode sheet, a band-like first separator sheet and a band-like second separator sheet laminated in a predefined order, the apparatus comprising:

• a winding shaft having an outer circumferential surface of an oval shape including a pair of flat surfaces facing each other and a pair of arcked surfaces connecting both of ends of the pair of flat surfaces to each other, the winding shaft allowing the lamination sheet to be wound around the outer circumferential surface thereof;
• a winding shaft driving device rotating the winding shaft;
• a feeding device feeding the lamination sheet toward the winding shaft;
• and
• a controller controlling the winding shaft driving device to control the rotation of the winding shaft and controlling the feeding device to control a length of the lamination sheet to be fed;
• wherein the controller controls the feeding device to feed the lamination sheet by, per rotation of the winding shaft, a length longer than an outer circumferential length corresponding to the number of winds of the lamination sheet wound around the winding shaft.

A power storage device, comprising:

• a wound electrode assembly including a lamination sheet in a state of being wound a plurality of times, the lamination sheet including a band-like positive electrode sheet, a band-like negative electrode sheet, a band-like first separator sheet and a band-like second separator sheet laminated in a predefined order,
• wherein:
• the wound electrode assembly is wound to have an oval shape including a pair of flat portions facing each other and a pair of arcked R portions connecting both of ends of the pair of flat portions to each other, and the lamination sheet includes a plurality of curved portions forming the R portions, the plurality of curved portions being laminated on each other in a diametrical direction of the R portions, and
• an inner circumferential length of one curved portion among the plurality of curved portions is longer than an outer circumferential length of another curved portion among the plurality of curved portions immediately inner to the one curved portion.