US Patent 10276902 Secondary battery having improved safety

A pouch type secondary battery includes an electrode assembly and a pouch sheath material including a first pouch portion and a second pouch portion. The pouch-type secondary battery includes dual electrode leads wherein a first electrode lead is attached to the first pouch portion and a second electrode lead is attached to the second pouch portion. In the pouch-type secondary battery, electric current is interrupted by using a volumetric swelling phenomenon caused by swelling or pressure generated upon overcharge so that the battery may be prevented from being further charged. In addition, when pressure is increased by an additional reaction, venting occurs toward the inner lead portion of each of the dual electrode leads. As a result, it is possible to increase the stability of a battery cell, module and a pack received in the pouch, and thus to improve the life of a battery.