Patent ID: 8790821

Claim:
A battery comprising: a battery case containing a power generating element therein and whose top surface is opened; a lid covering the top surface of the battery case, the lid having a through hole; a current collector connected to the power generating element; a rivet inserted into the through hole in the lid and connected to the current collector; a gasket interposed between the rivet and the battery case; and an external terminal connected to the rivet, wherein a first end of the rivet in an axial direction is connected to the current collector and provided with a tubular portion having outer and inner surfaces, the inner surface defining a recess recessed in the axial direction, a bottom surface of the recess reaches the through hole of the lid or exceeds the through hole toward a second end opposite from the first end in the axial direction, a thickness between the outer and inner surfaces continuously increases from the first end toward the second end, and an external diameter of the tubular portion decreases continuously from the first end toward the second end, wherein a rate of the increase of the thickness is greater than that of the decrease of the external diameter.