β-FeOOH on carbon nanotubes as a cathode material for Na-ion batteries

Sodium ion batteries (SIBs) have attracted extensive attention in recent years. However, the large volume change of cathode materials during the charge and discharge processes impedes the progress and application of SIBs. In this paper, three-dimensional (3D) tetsubo-like Beta-iron oxy-hydroxide (β-FeOOH) nano-cuboids on carbon nanotubes (CNTs) are synthesized by a simple solution method and used as cathode for SIBs. The β-FeOOH exhibits a (2×2) tunnel-type configuration, which can provide huge space for reversible sodium. The radial distribution of β-FeOOH nano-cuboids on the CNTs provides plenty cushion space and sufficient contact area with electrolyte during charge and discharge processes. Furthermore, the CNTs can enhance the electric conductivity and prevent the nanocomposite from agglomeration. Benefiting from the unique structure, the hybridization nanocomposite delivers a high initial discharge capacity (271 mA h g−1 at 10 mA g−1), long cycle life (120 mA h g−1 after 150 cycles with ~0.1% capacity decay per cycle at 120 mA g−1) and high rate performance (118 mA h g−1 at a current density of 240 mA g−1). These results indicate that the β-FeOOH@CNTs nanocomposite electrode may be a promising candidate for SIBs. Our work may provide a new way to construct and design high-performance cathode electrode materials for SIBs and related systems.