Hybrid-Mechanism Synergistic Flexible NbO@WS@C Carbon Nanofiber Anode for Superior Sodium Storage.

Sodium-ion batteries (SIBs) have demonstrated remarkable development potential and commercial prospects. However, in the current state of research, the development of high-energy-density, long-cycle-life, high-rate-performance anode materials for SIBs remains a huge challenge. Free-standing flexible electrodes, owing to their ability to achieve higher energy density without the need for current collectors, binders, and conductive additives, have garnered significant attention across various fields. In this work, we designed and fabricated a free-standing three-dimensional flexible NbO@WS@C carbon nanofiber (CNF) anode based on a hybrid adsorption-intercalation-conversion mechanism of sodium storage, using electrospinning and hydrothermal synthesis processes. The hybrid structure, aided by synergistic effects, releases the advantages of all materials, demonstrating a superior rate performance (288, 248, 211, 158, 90, and 48 mA h g at the current density of 0.2, 0.5, 1, 2, 5, and 10 A g, respectively) and good cycling stability (160 mA h g after 200 cycles at 1 A g). This work provides certain guiding significance for future research on hybrid and flexible anodes of SIBs.