摘要
This study presents a method to suppress the migration of lithium polysulfides in lithium–sulfur batteries by introducing a dual-layer electrode structure. Herein, unlike conventional methods of mixing the polar additives with sulfur/carbon composites, melted sulfur mixed with mesocarbon microbeads are used as the electrode and covered with an additive layer of Nb-doped TiO 2 /graphite composite via two-step blade coating. By doping TiO 2 with Nb, electrical and lithium ion conductivity of TiO 2 can be increased, thereby enhancing the redox reaction kinetics. Most importantly, chemisorption of lithium polysulfides to Nb–TiO 2 can effectively mitigate the shuttle effect, resulting in higher capacity and longer cycle life. The electrode with the Nb–TiO 2 additive layer results in a 1st and 100 th cycle specific capacity of 1883 mAh g −1 and 894 mAh g −1 , respectively, at 0.1 C (1 C = 1675 mAh), indicating enhanced electrochemical performance as compared with that of bare lithium-sulfur batteries. X-ray photoelectron spectroscopy (XPS) study was conducted to investigate the interaction between polysulfides and Nb–TiO 2 . The results indicate that the Nb–TiO 2 –layered electrode efficiently traps polysulfides on the cathode and improves the rate capability, cycle performance, and specific capacity.