Surfactant assisted electrospinning of WS2 nanofibers and its promising performance as anode material of sodium-ion batteries

Metal sulfides were considered as a promising anode material for sodium-ion batteries (SIBs). However, volume expansion during charging/discharging is an issue. One dimensional nanofibers are considered here to alleviate the change in stress of the anode's structure. Here we incorporated the nanofibers and WS₂ nanosheets which used (DODA)₃PW₁₂O₄₀ as the precursor. The precursor was prepared by an ion-exchange method, and then used to fabricate the anode material (denoted as DODA-WS₂) via electrospinning. Use of surfactant dimethyldistearylammonium bromide (DODA·Br) disperses the WS₂ nanosheets in the nanofibers. Carbonization and decomposition of DODA ligands provides porosity that accommodates volume expansion. The resulting structure of the anode material delivers high capacities of 363 and 318 mAh g⁻¹ with 96% and 91% rate capacity retention after 400 cycles at 200 and 500 mA g⁻¹, respectively. Also, improved rate capabilities (395 and 91 mAh g⁻¹ at 50 and 10000 mA g⁻¹, respectively) and good cycling stability (226.5 mAh g⁻¹ after 800 cycles at 1000 mA g⁻¹). These unique results are ascribed to the well-dispersed WS₂ cross-linked nanofiber framework and its conductive network. This structure facilitates the transportation of electrons and Na⁺ and relieve the stress due to expansion. DODA-WS₂ has a high potential for use as anode materials in SIBs.