| 摘要 |
PURPOSE:To improve the large current charge-discharge characteristics by providing irregularity at the bottom of a case containing a spiral-type electrode group and welding the lower end of a positive or a negative plate to the irregularity. CONSTITUTION:In order to weld an end surface 11 of a negative electrode 2 to a convex part 10 of irregularity which is provided at the internal bottom surface of a case 1, the upper surface of a positive electrode 3, which constitutes a spiral-type electrode group together with a negative electrode 2 and a separator 4, is welded to a positive collector 5 and inserted in the case 1. Next, a presser jig is pressed on the electrode group and, on the other hand, electrode bars 14, 15 for welding are pressed on the outer bottom of the case 1, and the current flows through. By the arrangement, the bottom surface between electrode rods 14, 15 of the case is heated to high temperatures, resulting in welding to a corresponding negative electrode. The same welding operation is repeated radially to the bottom surface several times. It results in improving the large current charge-discharge characteristics. |
