Lithium secondary battery having case with simplified safety device

DETAILED DESCRIPTION To satisfy the above demands, it is an object of the present invention to provide a cheap and simplified safety device for a lithium secondary battery.
Accordingly, to achieve the above object, there is provided a lithium secondary battery encased in a pouch including a positive electrode terminal and a negative electrode terminal, both of electrodes extending upward with respect to the pouch, one of the electrode terminals having extension which wraps around the pouch, a lead end of the extension forming a new terminal wherein the extension includes a notch where the extension is narrower.
When a battery operates abnormally, that is, when a battery operates with a voltage higher than the operational voltage thereof or when a positive electrode and a negative electrode are shorted, gases are produced and the pouch swells accordingly.
Then, the extended terminal which wraps around the pouch also swells.
Due to swelling of the terminal, a stress is intensively applied to a notch of the terminal.
As a result, excessive swelling of the pouch cuts the notch.
Thus, the flow of current is interrupted to inhibit further reaction.