Study of Me-x(VO3)(2) vanadates, (Me = Co, Ni, Mn, 1 < x < 2) for lithium rechargeable cells

Transition metal vanadates, Me-x(VO3)(2) . 2H(2)O, where Me = Co, Ni, and M n and 1.0 <x< 2.0, were found to reversibly insert lithium. The efficiency of reversible insertion depended on both the transition metal present and t he stoichiometric ratio of Me:V in the vanadate structure. The Ni and Co va nadates gave the highest specific capacities using lithium metal coin cells , with initial specific capacities above 0.7 A h/g (1.0 W h/g) when x is ne ar 1.0. The operating voltage of these materials was in the range of 1.0 to 2.0 V. Lithium ion coin cells using LiCoO2 coupled with the vanadates, wer e also examined. These were found to deliver about 200 mA h/g, with average voltages of 2.5 to 2.0 V for values of x from 1.1 to 1.2. (C) 1999 Elsevie r Science S.A. All rights reserved.