| 摘要 |
<p>A sealed battery has an opening in an external casing (10) sealed using a sealing plate (31) that is laser welded to external casing (10). The sealing plate (31) has a drop (312) formed near a perimeter of the external surface of the sealing plate (31) so that the surface of the sealing plate is higher at a perimeter of the sealing plate than at a more central position. When the sealing plate (31) is laser welded to the rim of the external casing, the presence of the drop means that there is no direct thermal conduction path from the welded parts to the center of the sealing plate, which reduces the dissipation of heat away from the welded parts. As a result, there is a reduction in the thermal stresses that occur at the welded parts, which means that the formation of cracks in the welded joins can be suppressed, even when a low-power laser beam is used. <IMAGE> <IMAGE></p> |
