Insights into the storage mechanism of freestanding MoTe2/C nanofibers as binder-free anodes for high-performance sodium-ion batteries

Developing flexible and binder-free electrodes with superior electrochemical performance is the critical key for flexible electronics and wearable devices . MoTe 2 , a typical two-dimensional (2D) layered material, has emerged as an attractive anode material for sodium ion batteries (SIBs) because its abundant active sites and rapid Na + transfer and storage. In this work, a series of flexible MoTe 2 /C nanofibers (NFs) are successfully synthesized via a facile electrospinning process with tellurization treatment. As binder and current collector-free anodes, the optimized MoTe 2 /C-600 shows significantly enhanced Na + storage performance, which delivers a high reversible capacity of 294 mAh g −1 after 100 cycles at 0.1 A g −1 and an ultra-long time cycling performance of 5000 cycles at 1.0 A g −1 . The as-prepared MoTe 2 /C NFs possess double merits of well 1D conductive paths and 3D ion diffusion channels, which effectively boost the electron/Na + transfer. Meanwhile, its excellent flexibility and mechanical strength greatly enhance the cycling stability. More importantly, in-situ X-ray diffraction and ex-situ transmission electron microscope were employed to demonstrate its structure evolution, revealing that the high capacity of MoTe 2 /C-600 results from the cooperation of Na + intercalation and conversion reaction. The findings of this study provide a better understanding on the sodium storage mechanism of MoTe 2 -based flexible electrodes.