Fluorine-Doped Nb2O5 with Rich Oxygen Vacancies Anchored on the N/F Carbon Skeleton for Superior Lithium Storage

With the aim of improving the intrinsic conductivity of Nb2O5, we synthesized fluorine-doped Nb2O5 with rich oxygen vacancies anchored on the N/F carbon skeleton (F–Nb2O5@NFC) by a one-step annealing method. In this structure, F-doping greatly improves the intrinsic conductivity of Nb2O5, and the theoretical calculation results show that F–Nb2O5 has surprisingly zero band gap metal characteristics. At the same time, due to F-doping, a large number of oxygen vacancies are introduced into the structure, which increases the concentration of free electrons and further enhances the conductivity of the composites. In addition, the N/F codoped carbon skeleton ensures the rapid transmission of electrons. Under the blessing of multilevel conduction, F–Nb2O5@NFC exhibits excellent electrochemical performance, with a reversible specific capacity of 130 mAh g–1 after 1400 cycles at a current density of 3 A g–1, and the rate capacity reaches 110 mAh g–1 at a high current density of 10 A g–1.