Patent ID: 8822055

Claim:
A secondary battery comprising: a cross-sectionally elliptic electricity-generating element group in which a positive electrode sheet including at one side in a longitudinal direction thereof a section not coated with an active material mixture, and a negative electrode sheet including at one side in a longitudinal direction thereof a section non-coated with an active material mixture are wound via separators in such a form that the non-coated sections of the positive and negative electrode sheets are arranged on sides opposite to each other; a battery container to accommodate the electricity-generating element; a positive electrode connecting sheet and a negative electrode connecting sheet, both connected at one side of each thereof to the non-coated sections of the positive and negative electrode sheets, respectively, that are positioned at end portions of a planar region present between curves formed by winding the positive and negative electrode sheets of the electricity-generating element group; and a positive electrode external terminal and a negative electrode external terminal, both fixed to the battery container and each connected to the other side of each of the positive and negative electrode connecting sheets; wherein: when the planar region of the electricity-generating element group is seen in plan view, the number of connections, between the non-coated section of the positive or negative electrode sheet and one side of the positive or negative electrode connecting sheet, is two for each of positive and negative electrodes; and a distance between the two connections is greater than ¼ of an innermost circumferential length of the wound positive and negative electrode sheets of the electricity-generating element group, but is smaller than ¼ of an outermost circumferential length of the wound positive and negative electrode sheets of the electricity-generating element group.