A NEW HYDRATED SODIUM VANADIUM BRONZE AS LI INSERTION COMPOUND

A sodium vanadium bronze hydrate, Na0.33V2O5 . 1.3H(2)O has been synth esized from reaction of phosphonic acid with vanadyl ions and sodium h ydroxide in aqueous solution. The electrochemical Li insertion has bee n investigated in this layered structure characterized by a basal spac ing of 10.84 Angstrom. Its behaviour differs from that known for the s ol-g-el sodium-exchanged V2O5 xerogel and for the anhydrous monoclinic bronze. The presence of water does not hinder Li accommodation and tw o 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. Preliminar y chronopotentiometric and cyclic voltammetric experiments indicate th e potential interest of such a hydrated vanadium pentoxide bronze for reversible Li insertion reactions. (C) 1998 Published by Elsevier Scie nce B.V. All rights reserved.