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

Abstract

With the aim of improving the intrinsic conductivity of Nb 2 O 5 , we synthesized fluorine-doped Nb 2 O 5 with rich oxygen vacancies anchored on the N/F carbon skeleton (F−Nb 2 O 5 @ NFC) by a one-step annealing method. In this structure, F-doping greatly improves the intrinsic conductivity of Nb 2 O 5 , and the theoretical calculation results show that F−Nb 2 O 5 has surprisingly zero band gap metal characteristics. At the same time, due to Fdoping, 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− Nb 2 O 5 @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 .