| abstract |
An alkali metal secondary electrochemical cell, andnpreferably a lithium ion cell (10), provided with a removablengas relief valve (12), is described. The gas release valvenis positioned on the casing (14), in fluid flow communicationnbetween the inside thereof and the exterior. This gasnrelease valve serves to eliminate cell gases that buildnup inside the casing during the cell's formation stage.nOnce the lithium-ion cell has completed formation, thengas release valve is removed and replaced with anhermetic closure. Removal of the gas release valve andnsealing of the cell takes place in an environment innwhich no outside gas is capable of being introducedninside the casing. The cell can also be provided in antank filled with inert gas and a filter which separatesnthe cell gas from the inert gas. When cell formation isncompleted, the cell hermetically sealed. |