WS Nanotube-Embedded SiOC Fibermat Electrodes for Sodium-Ion Batteries.

Layered transition metal dichalcogenides (TMDs) such as tungsten disulfide (WS) are promising materials for a wide range of applications, including charge storage in batteries and supercapacitors. Nevertheless, TMD-based electrodes suffer from bottlenecks such as capacity fading at high current densities, voltage hysteresis during the conversion reaction, and polysulfide dissolution. To tame such adverse phenomena, we fabricate composites with WS nanotubes. Herein, we report on the superior electrochemical performance of ceramic composite fibers comprising WS nanotubes (WSNTs) embedded in a chemically robust molecular polymer-derived ceramic matrix of silicon-oxycarbide (SiOC). Such a heterogeneous fiber structure was obtained via electrospinning of WSNT/preceramic polymer solution followed by pyrolysis at elevated temperatures. The electrode capacity fading in WSNTs was curbed by the synergistic effect between WSNT and SiOC. As a result, the composite electrode exhibits high initial capacity of 454 mAh g and the capacity retention approximately 2-3 times higher than that of the neat WSNT electrode.