Rational construction and decoration of Fe0.5Nb24.5O62−x@C nanowires as superior anode material for lithium storage

Abstract Niobium-based oxides have recently attracted great attention as anode material for lithium ion batteries (LIBs) because of high theoretical capacity, high working potential and outstanding rate performance. Nevertheless, the practical capacity of niobium-based oxides still cannot meet the demand for electrical energy storage applications in electric vehicles for low conductivity and poor ion transfer. Here, the Fe0.5Nb24.5O62−x@C nanowires are constructed by introduction of oxygen vacancy and carbon coating layer, which largely improves electron/ion conductivity. The Fe0.5Nb24.5O62−x@C nanowires exhibit outstanding capacity (initial capacity of 273.1 mAh g−1 with Coulombic efficiency at 92.19%), and excellent cycle performance (213.9 mAh g−1 after 2000 cycles at current density of 0.1 A g−1). Owing to the pseudocapacitive contribution, the Fe0.5Nb24.5O62−x@C nanowires also present a wonderful electrochemical performance under extremely high rates. Moreover, the uptake/release mechanism in Fe0.5Nb24.5O62−x@C nanowires during electrochemical lithiation/delithiation process is investigated via in-situ X-ray diffraction (XRD) measurement. To meet the possible applications, a full cell is assembled by using Fe0.5Nb24.5O62−x@C as anode and LiCoO2 as cathode, which delivers a high capacity of 130.6 mAh g−1 at 0.1 A g−1, indicating great potential for practical applications. Thus, this novel strategy for preparing Fe0.5Nb24.5O62−x@C nanowires may inspire researchers to develop high-performance niobium-based electrodes for LIBs.