CYLINDRICAL SECONDARY BATTERY

摘要

The invention provides a cylindrical secondary battery in which the contact portion between the bottom surface of a seal (12) and a projection (20) formed on a collector lead plate (71) is welded by feeding an electric current to the external terminals of the positive and negative electrodes of the battery, wherein a groove (40) is formed in the bottom surface of the seal in a concentric circle drawn about the center of the seal, the width of the groove (40) decreases in the direction from an opening (42) to the deepest part (41), and the distal end of the projection (20) formed on the collector lead plate (71) is fitted into the groove (40) in the bottom surface of the seal and is welded to the bottom surface of the seal.