Effective sulfur-salt composite cathode containing lithium bis(trifluoromethane) sulfonamide for lithium sulfur batteries

- A sulfur-salt composite electrode containing LiTFSI salt were synthesized by a simple ball-milling procedure.
- The resultant Li-S batteries exhibited a high initial discharge capacity of 1343 mAh g−1.
- These sulfur-salt Li-S batteries manifested excellent cyclic performance.

To improve the utilization of the active materials and the cyclic performance of the lithium sulfur (Li-S) battery, we designed a sulfur-salt composite cathode that was prepared by the simplest ball-milling method and employed lithium bis(trifluoromethane) sulfonamide (LiTFSI) as one of the cathode components. It is found that the presence of LiTFSI salt plays an important role in increasing the lithium ionic conductivity, enlarging the ion exchange area of the aggregation insulating sulfur particles, and promoting the electrochemical reaction kinetic performance to optimize the utilization of active materials. As a result, the as-prepared cathode shows a pronounced high capacity of 1342 mAh g−1 and excellent coulombic efficiency of nearly 100%. Additionally, the scanning electron microscopy (SEM) images confirmed the alleviated loss of active materials in the resultant sulfur-salt cathode. Furthermore, the high-capacity retention and improved electrochemical kinetic performance were validated by charging and discharging tests, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). This effective and simple method provides a new methodology for attaining high-energy Li-S batteries via electrode materials preparation without complex chemical synthesis procedures.