Rod-like NaV3O8 as cathode materials with high capacity and stability for sodium storage

In this study, NaV3O8 nanorods are successfully prepared using nonionic surface-active agents Pluronic-F127 as structure-directing agent. The as-prepared NaV3O8 nanorods calcinated at different temperatures are characterized by various techniques, including X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy. The NaV3O8 calcinated at 400 degrees C for 20 h shows appropriate sizes and uniform morphologies of the nanorods, 4-7 mu m in length and 0.2-0.5 mu m in diameter. The NaV3O8 nanorods as cathode materials for Na-ion batteries deliver high discharge capacity reaching up 110.4 mAh g(-1) at current density of 120 mA g(-1), as well as long lifespan by maintaining capacity of 162.1 mAh g(-1) after 500 charge-discharge cycles. Also, a high reversible capacity of 83.9 mAh g(-1) can be retained after 500 cycles at high rate of 2 A g(-1). The obtained outstanding electrochemical performances are associated with the unique micro-nano structures, which does not only facilitate transport of Na+ ion, but also resist erosion from electrolytes. Overall, the results suggest the promise of NaV3O8 nanorods as cathode materials for high capacity, high power and long lifespan Na-ion batteries. This work may open an innovative route to discover diverse electrode materials with nanostructure for energy storage system.