Solution phase synthesis of Na0.28V2O5 nanobelts into nanorings and the electrochemical performance in Li battery

In this paper, we are the first to report a simple one step hydrothermal method to synthesize Na0.28V2O5 nanorings/nanobelts without using any organic surfactant/solvents at 130–160 °C for 1–2 days. The obtained products have been characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, morphology by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and electrochemical discharge–charge test for lithium battery. XRD pattern exhibit a monoclinic Na0.28V2O5 structure. FTIR spectrum shows band at 958 cm−1 is assigned to VO stretching vibration, which is sensitive to intercalation and suggests that Na+ ions are inserted between the vanadium oxide layers. TEM analyses reveal that the products consist of nanorings of width about 500 nm and thickness of about 100 nm with inner diameter of 5–7 μm. Nanobelts of width 70–100 nm and several tens of micrometers in length are observed. The electrochemical results show that nanorings/nanobelts exhibit an initial discharge capacity of 320 mAh g−1 and its capacity still retained 175 mAh g−1 even after 69 cycles. We have discussed the possible growth mechanism for the formation of nanorings/nanobelts.