PURPOSE: To improve liquidtightness by caulking the opening end part of a cell case, keeping the difference between the case inner diameter and gasket outer diameter to be 0.1∼0.2% of the case inner diameter in the region from the upper end of the cell case opening part to midway of the case height.
CONSTITUTION: In case that a sealing plate 2 also used for a negative electrode terminal fitted with a gasket 4 is inserted into a cell case 1 also used for a positive electrode terminal and the opening end part of the case 1 is caulked inward and thereby a flat-type lithium cell or the like is formed, such a gasket 4 that the fitting clearance between the gasket 4 and the case 1 is limited to 0.1∼0.2% of the case inner diameter in the region from the opening part of the case 1 to a half length of the case height, and at the same time, said clearance is uniform in longitudinal direction of the inner face of the case 1 is used and said clearance is sealed by applying sealant 7. Therefore, its adhesive capability at the time of sealing is greatly improved and lekage of liquid from between the case 1 and gasket 4 is prvented and thereby its liquidtightness can be improved.
YAGIYUU YASUSABUROU
KIMURA ISAO
