The intercalation chemistry of H sub(2)V sub(3)O sub(8) nanobelts synthesised by a green, fast and cost-effective procedure

• Published in: Journal of power sources Vol. 232; pp. 173 - 180
• Main Authors: Prado-Gonjal, J, Molero-Sanchez, B, Avila-Brande, D, Moran, E, Perez-Flores, J C, Kuhn, A, Garcia-Alvarado, F
• Format: Journal Article
• Language: English
• Published: 15.06.2013
• Subjects: Electrodes; Insertion; Lithium; Nanocomposites; Nanomaterials; Nanostructure; Reduction; Scanning electron microscopy
• ISSN: 0378-7753

H sub(2)V sub(3)O sub(8) nanobelts have been successfully synthesised from commercial V sub(2)O sub(5) powder through a fast and environmental friendly microwave-hydrothermal method. X-ray diffraction, field-emission scanning electron microscopy, thermogravimetric analysis, infrared spectroscopy, high-resolution transmission electron microscopy and ICP spectroscopy were used to characterise the morphology and structure-microstructure details. Nanobelts about 100 nm wide and several micrometres long are easily prepared in no more than 2 h. The electrochemical study reveals the reversible insertion of ca. 4 Li per formula unit (400 mAh g super(-1)), through several pseudo-plateaus in the 3.75-1.5 V vs Li super(+)/Li voltage range showing the interest of this material produced by a "green" route as an electrode for lithium rechargeable batteries. After the first cycle a significant capacity loss is observed, though a high capacity, ca. 300 mAh g super(-1), remains upon cycling. Furthermore, the similarity of discharge and charge curves, pointing to the absence of hydrogen displacement during lithium insertion in H sub(2)V sub(3)O sub(8), shows that not all protonated systems must be discarded as prospective electrode materials. On the other hand, further reduction down to 1 V is possible to insert up to 5 Li per formula unit (480 mAh g super(-1)). Interestingly it corresponds to full reduction of vanadium to V super(3+) as it is also confirmed by EELS experiments. However, the full reduction to V super(3+) is associated with a fast decay of the extra capacity developed at low voltage with increasing current rate. Then for practical use we may consider only the capacity obtained down to 1.5 V.