SECONDARY BATTERY OF IMPROVED OVERCHARGE SAFETY

摘要

A secondary battery having improved overcharge safety is provided to allow a current interruptive device to operate before thermal runaway upon an overcharge state so as to induce a short circuit, thereby improving the safety of the battery while not adversely affecting the quality of the battery. A secondary battery comprises a current interruptive device(CID)(20) that operates upon an increase in the internal pressure of the battery to interrupt electric current, and further comprises a material capable of lithium ion deintercalation under an overcharge condition in a cathode so that the internal pressure of the battery increases under the overcharge condition to allow the CID to operate before thermal runaway. The material capable of lithium ion deintercalation is used in an amount of 0.01-20 wt% based on the weight of the cathode active material, and includes a lithium transition metal composite oxide.