US Patent 8409736 Cap assembly with desirable safety performance

A cap assembly with desirable safety performance for use in lithium ion batteries, includes an insulating gasket defining a through hole therein, a rupture plate positioned in the through hole, a vent plate defining an air hole electrically connected with the rupture plate, a current interrupt device disposed on the rupture plate, and an end cap defining an air exhaust hole assembled on the current interrupt device. The current interrupt device has an upper conductive plate electrically connected with the end cap, a lower conductive plate electrically connected with the rupture plate, and a fuse electrically connecting the upper conductive plate and the lower conductive plate. When the current intensity in the lithium ion battery exceeds a predetermined value, the fuse melts to cut off the current path.