Secondary battery employing safety device

Abstract

Disclosed herein is a secondary battery having a mechanical connection sensor, as a safety device, fixed to the outer surface of a prismatic or pouch-shaped battery cell while the mechanical connection sensor is set to OFF. The mechanical connection sensor is connected in series with a resistor having a predetermined resistance value and with a cathode and an anode of the battery cell. When the battery cell swells to a critical value or more due to the abnormal operation of the battery cell, the mechanical connection sensor is turned ON, and therefore, the mechanical connection sensor conducts with the result that the electrical energy of the battery cell is consumed at the resistor. In the secondary battery having the safety device according to the present invention, when the battery swells due to the abnormal response of the battery, energy accumulated in the battery is forcibly consumed, unlike a conventional battery that merely intercepts the current. As a result, the continuous occurrence of the abnormal response is fundamentally prevented, and therefore, more rapid process is possible with excellent pressure sensitivity. Consequently, the safety of the battery is improved.