Abstract: A battery includes a negative electrode body wound to be flat. The negative electrode body has a plurality of negative electrode main bodies arranged in a line in a negative electrode connection direction in a developed state, and at least one negative electrode connection portion connecting a pair of negative electrode main bodies adjacent in the developed state among the plurality of negative electrode main bodies. The at least one negative electrode connection portion is folded back such that the plurality of negative electrode main bodies overlap each other. A dimension of each of the plurality of negative electrode main bodies in the negative electrode connection direction decreases with separation from an outer end side negative electrode main body. A dimension of the at least one negative electrode connection portions in the negative electrode connection direction increases with separation from an inner end side negative electrode connection portion.

Abstract: An electrochemical cell includes an electrode body that has a plurality of electrodes stacked on each other in a direction of a battery axis O, and an exterior body that has a first laminate member and a second laminate member, and that internally accommodates the electrode body. The exterior body includes an accommodation portion that internally accommodates the electrode body, and a sealing portion in which the first laminate member and the second laminate member are joined to each other in a state where the first laminate member and the second laminate member overlap each other so as to seal an inside of the accommodation portion. The accommodation portion includes a top wall portion and a bottom wall portion which face each other with the electrode body interposed therebetween in the direction of the battery axis, and a cylindrical peripheral wall portion which surrounds the electrode body from an outer side in a radial direction.

Abstract: A battery includes a negative electrode body wound to be flat. The negative electrode body has a plurality of negative electrode main bodies arranged in a line in a negative electrode connection direction in a developed state, and at least one negative electrode connection portion connecting a pair of negative electrode main bodies adjacent in the developed state among the plurality of negative electrode main bodies. The at leak one negative electrode connection portion is folded back such that the plurality of negative electrode main bodies overlap each other. A dimension of each of the plurality of negative electrode main bodies in the negative electrode connection direction decreases with separation from an outer end side negative electrode main body. A dimension of the at least one negative electrode connection portions in the negative electrode connection direction increases with separation from an inner end side negative electrode connection portion.