Secondary Battery and Method for Manufacturing Same

Provided is a secondary battery comprising: an electrode assembly; a battery case which accommodates the electrode assembly; a first electrolyte which is accommodated in the battery case and primarily impregnates the electrode assembly; and a reinforcement electrolyte member which comprises a packaging material and a second electrolyte, wherein the packaging material is accommodated in the battery case and provided with an oxidation part which is oxidized and decomposed at a set voltage, and the second electrolyte is stored in the packaging material, released to the outside of the packaging material due to the decomposition of the oxidation part, and secondarily impregnates the electrode assembly.