Constructing FeTe2 nanoparticles embedded in N-doped carbon nanofiber composites as a long-life and high-rate anode material for sodium-ion batteries

Tellurium metal exhibits notably high electrical conductivity along with low electronegativity. The exploration of various metallic tellurides for sodium-ion storage has garnered significant attention among researchers. In this study, we successfully synthesized FeTe2/carbon nanofibers (FeTe2/CNFs) using the electrospinning technique, where FeTe2 nanoparticles are embedded within nitrogen-doped carbon nanofibers. Functioning as a sodium-ion anode, the FeTe2/CNF composite initially demonstrated a remarkable capacity of 406.8 mA h g(-1). Even after undergoing 1000 cycles at a current density of 1 A g(-1), it retained a reversible specific capacity of 221.3 mA h g(-1). Impressively, at a substantially higher current density of 30 A g(-1), the FeTe2/CNFs anode exhibited a reversible specific capacity of 101.1 mA h g(-1). This exceptional performance can be attributed to the synergistic effect between FeTe2 nanoparticles and carbon nanofibers. The physical confinement effect of the carbon nanofibers effectively restrains volume expansion and prevents detachment and crushing of the active materials. Additionally, the presence of both carbon and iron in the nanofibers facilitates the formation of Fe-C covalent bonds. These bonds serve to safeguard the FeTe2 particles from crushing during the sodium-ion insertion/extraction processes. Consequently, FeTe2/CNFs display significant potential as anode materials suitable for practical applications in sodium-ion storage.