SECONDARY BATTERY CAPABLE OF EQUALIZING INTERNAL/EXTERNAL PRESSURE

Various embodiments of the present invention pertain to a secondary battery, and a technical problem thereof to be solved is providing a secondary battery that is capable of equalizing internal/external pressure. To this end, disclosed in the present invention is a secondary battery comprising: an electrode assembly; a case that accommodates the electrode assembly; a cap plate that seals the case, and that has a safety vent that is ruptured when internal pressure of the case rises; a terminal portion that is electrically connected to the electrode assembly, and that extends outwardly from the cap plate; and a pressure equalization structure that is formed on the cap plate so as to equalize the internal pressure and external pressure of the case.