A battery based on the lithium/elemental sulfur redox couple has high theoretical specific capacity of 1,675 mAh/g-sulfur and theoretical specific energy of 2,600 Wh/kg, assuming the complete reaction of lithium with sulfur to $Li_2S$. And the use of sulfur as cathode active material is advantageous as it is relatively cheap and non-poisonous material. Although the Li/S battery has many advantages, Li/S battery with a sulfur cathode has bad cyclic durability at room temperature. Therefore, in order to commercialize Li/S battery, it is most necessary to improve the cycle life of Li/S battery.
The discharge process of the Li/S battery proceeds by two steps. The first step is the transformation of sulfur to lithium polysulfide $(Li_2S_n, 2
