Regulation Polysulfide Conversion by Flexible Carbon Cloth/Molybdenum Selenide to Improve Sulfur Redox Kinetics in Lithium-Sulfur Battery

Lithium-sulfur (Li-S) batteries have been regarded as a competitive candidate for next generation electrochemical energy-storage technologies. However, the insulation of charge and discharge products (sulfur and lithium sulfide) and the shuttle efforts of lithium polysulfides (LiPSs), result in not only a series of phase conversion but also sluggish redox kinetics in Li-S electrochemistry. Herein, we firstly designed a flexible carbon cloth/molybdenum selenide (CC/MoSe2) by growing ultra-thin MoSe2 nanosheets on CC as binder-free electrode to understand the regulation mechanism in Li-S battery. With systematic electrochemical investigation of in-situ deposition Li2S8 in CC/MoSe2, it is found that CC/MoSe2 exhibits high LiPSs chemical adsorption and electrocatalytic activity, which large enhances the LiPSs conversion. The dynamic regulation of LiPSs change the nucleation and growth of Li2S, resulting in high uniform distribution on CC/MoSe2 electrode. Thus, it obtains high sulfur redox kinetics and utilization, which achieves initial capacity of 1142 mAh g-1 with low capacity fade of only 0.038 % per cycle over 500 cycles at 1 C. Even at high S loading (4 mg cm-2) and extremely low electrolyte/S (E/S) ratio of 6.2 μL mg-1, it still delivers 1204 mAh g−1 after 100 cycles at 0.2C with 93.3% capacity maintain.