Origin of the improved cycling capability of sol-gel prepared Fe0.12V2O5.16 compared with V2O5

A new vanadium iron oxide has been synthesized starting from V2O5 xerogel through an exchange reaction. In its Rietveld-determined structure, (FeO6) apex sharing octahedra link V2O5 ribbons and increase the three-dimensional character of the material. This latter point seems to improve the electrochemical behaviour when compared with V2O5. Especially, in terms of cycle life, a capacity of 210 Ah/kg is maintained after 40 cycles in the potential window of 3.8-2 V instead of 150 Ah/kg for V2O5.