Sulfur/Multiwalled Carbon Nanotube Composite Cathode for High Performance Lithium/Sulfur Batteries

Abstract

Lithium/sulfur batteries have gained intense attention as one of the most promising candidates for high energy density rechargeable batteries due to their high theoretical specific capacity of 1672 mAh g -1 and theoretical energy density of 2600 Wh kg -1 based on cathode materials. In addition, sulfur has the advantages such as low cost, natural abundance, and environmental friendliness. Herein, we report on the preparation of the long-time stabilized MWNT aqueous suspension with the addition of sodium dodecylbenzene sulfonate (SDBS) surfactant, and a well-dispersed sulfur/multiwalled carbon nanotube (S/MWNT) composite synthesis via a simple stirring mixing of the resultant MWNT suspension with commercial nanosized sulfur aqueous suspension. This preparation method based on the suspension mixing possesses the advantages of simplicity and low cost. Homogeneous dispersion and integration of MWNT in the composite results in a porous, highly conductive and mechanically flexible framework with enhanced electronic conductivity and ability to absorb the polysulfides into its porous structure. The cell with this S/MWNT composite cathode demonstrates a high reversibility, resulting in a stable reversible specific discharge capacity of 708 mAh g -1 after 100 cycles at 0.1 C. Furthermore, the S/MWNT composite cathode with sulfur content of 62.5 wt% exhibits a good rate capability with discharge capacities of 946, 780 and 516 mAh g -1 at 0.5, 1 and 1.5 C, respectively.