A new hydrated sodium vanadium bronze as Li insertion compound

A sodium vanadium bronze hydrate, Na0.33V2O5 . 1.3H(2)O has been synthesized from reaction of phosphonic acid with vanadyl ions and sodium hydroxide in aqueous solution. The electrochemical Li insertion has been investigated in this layered structure characterized by a basal spacing of 10.84 Angstrom. Its behaviour differs from that known for the sol-g-el sodium-exchanged V2O5 xerogel and for the anhydrous monoclinic bronze. The presence of water does not hinder Li accommodation and two main reversible insertion steps are found at 3.1 V and 2.65 V for a maximum Li uptake of 1.65 lithium ion per mole of compound. Preliminary chronopotentiometric and cyclic voltammetric experiments indicate the potential interest of such a hydrated vanadium pentoxide bronze for reversible Li insertion reactions. (C) 1998 Published by Elsevier Science B.V. All rights reserved.