A method for producing a lithium-sulfur battery with an improved lifetime. This method includes an activation step of forming a positive electrode active material-derived compound from a compound including elemental sulfur by charging and discharging the lithium-sulfur battery, where the battery includes the compound including elemental sulfur and an electrolyte liquid. Additionally, the positive electrode active material-derived compound has a solubility of 1% by weight or greater in the electrolyte liquid. The lithium-sulfur battery may be charged and discharged in a range of greater than 2.0 V and less than 2.4 V in the activation step. Further, the lithium-sulfur battery may be charged and discharged 3 times to 10 times in the activation step. This method avoids a complicated application process of and active material in preparing a lithium-sulfur battery.