Lithium Secondary Battery and Method of Replenishing Electrolyte in Lithium Secondary Battery

A lithium secondary battery includes an electrode assembly including a cathode and an anode facing the cathode, a case accommodating the electrode assembly, an electrolyte accommodated in the case together with the electrode assembly, and an electrolyte storage unit inserted into the case to supply a supplementary replenishment. The electrolyte storage unit includes a first unit including a first body having a tubular structure and first holes formed through the first body, and a sub-unit including a tubular body and sub-holes formed through the tubular body. The sub-unit is inserted into the first unit so that the sub-holes are offset from the first holes.