Improved Electrochemical Performance of NTs-WS 2 @C Nanocomposites for Lithium-Ion and Sodium-Ion Batteries.

Even though WS 2 nanotubes (NTs-WS 2 ) have great potential as anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) thanks to their unusual layered structure, their conductivity and cycling stability are far from satisfactory. To tackle these issues, carbon-coated WS 2 (NTs-WS 2 @C) nanocomposites were prepared through a facile synthesis method that involved precipitating a carbon precursor (20% sucrose) on WS 2 nanotubes, followed by annealing treatment under an argon environment. Thanks to the presence of highly conductive and mechanically robust carbon on the outer surface, NTs-WS 2 @C nanocomposites show improved electrochemical performance compared with bare NTs-WS 2 . After 60 cycles at 80 mA g -1 current density, the cells display high capacities of 305 mAh g -1 in LIBs and 152 mAh g -1 in SIBs, respectively. As the current density increases to 600 mA g -1 , it provides specific capacities of 209 and 115 mAh g -1 , correspondingly. The enhanced electrochemical performance in LIBs and SIBs is primarily attributed to the synergistic effects of the tubular architecture of WS 2 , carbon network and stable nanocomposite structure, which can effectively constrain volume variation during the metal ions intercalation/deintercalation processes.