S-sphere/C/MoS2 composite for high-performance Lithium-Sulfur batteries

With the development of energy storage systems, Lithium-Sulfur (Li-S) batteries represent an ideal choice due to extremely high theoretical specific capacity (1675 mAh/g(-1)) and energy density (2500 Wh/kg(-1)) of Sulfur cathode. However, it is a challenge to solve the electroconductibility of Sulfur, shuttle effect of polysulfide and volume expansion. Although tremendous works have been carried out to improve the capacity, the practical application of Li-S batteries is still hindered by low electroconductibility of Sulfur, poor cycle life and low rate performances. Herein, S-sphere/C/MoS2 composite was prepared by the melt diffusion method for the nanosulfur host. In comparison with the large particles sublimate Sulfur, nano-sulfur particles can shorten the diffusion path of ions and facilitate the smooth diffusion of Li+ into the interior of Sulfur at high discharging current densities. Therefore, the formation of insulating Li2S2 and Li2S is delayed. Moreover, the Few-layered MoS2 can be used to achieve chemical adsorption with Lithium polysulfide (LiPS) and Carbon spheres has good electronic conductivity, thus the rate performance and the cyclic capability of Li-S batteries have been improved. The S-sphere/C/MoS2 composite exhibits an initial discharging capacity of 1016.3 mAh/g(-1) at 0.1 C, and a high capacity of 753 mAh/g(-1) at 1 C with a low fade rate of 0.211%. These indicate that the S-sphere/C/ MoS2 composite has good electrochemical performance and is expected to be a candidate electrode for Li-S batteries industrialization in the future.