Patent ID: 8808900

Claim:
A cylindrical lithium ion secondary battery comprising: an electrode assembly; a center pin positioned within the electrode assembly; a circuit member contained in the center pin and adapted to be short-circuited when a charging voltage is equal to or larger than a reference voltage, the circuit member comprising: a reference voltage source for providing the reference voltage; a voltage comparator adapted to receive the reference voltage from the reference voltage source via a terminal, to receive a battery voltage via another terminal, and to output a short-circuit signal when the battery voltage is larger than the reference voltage; and a short-circuit switch connected in parallel to the battery and adapted to be toggled to an on setting by the short-circuit signal from the voltage comparator and to cause the battery to be short-circuited, the short-circuit switch being a transistor with a collector and an emitter connected in parallel to the battery, and a base connected to an output terminal of the voltage comparator; a heating member connected between the battery and the emitter of the transistor, the heating member having a gasification member mounted thereon, which gasifies at a predetermined temperature and increases an internal pressure of the battery; a can receiving the electrode assembly and the center pin, which contains the circuit member; and a cap assembly coupled to a top of the can, wherein the gasification member comprises at least one material selected from the group consisting of cyclo hexyl benzene (CHB) and biphenyl (BP).