Hierarchical WS2/C nanofibers with controlled interlayer spacing for high-performance sodium ion batteries

Hierarchical WS2/C nanofibers with controllable layer spacing are prepared by electrospinning combined with in-situ sulfurization at 800 ℃. The characterizations reveal that WS2 is uniformly embedded in the nanofibers; as well as adhering to the nanofiber surface with large layer spacing (0.76 nm). The hierarchical structure promotes rapid diffusion of Na+ and has a large contact area with the electrolytes, which improves the capacity of sodium-ion batteries (SIBs). As a result, the obtained WS2/C nanofiber electrode has high capacity and excellent cyclic stability. It demonstrates a special discharge capacity of 291 mAh g−1 with capacity retention of 99.1 % at the 200th cycle at a current density of 0.5 A g−1, even maintaining 159 mAh g−1 after 1000 cycles at 5 A g−1. Furthermore, theoretical calculations using the density functional theory (DFT) demonstrate that the WS2/C500-800 electrode obtained by annealing at 500 ℃ and vulcanization at 800 ℃ is conducive to Na+ storage. This work provides a solid theoretical basis for the industrialization of high specific capacity SIB anodes and the research of energy storage electronic devices. •Hierarchical WS2/C nanofibers by electrospinning combined with in-situ sulfurization were obtained.•The controlled interlayer spacing of WS2 was achieved.•The WS2/C nanofiber showed excellent performances for Na+ storage.