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

Abstract

Transition metal vanadates, Me x (VO 3 ) 2 ·2H 2 O, where Me=Co, Ni, and Mn 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 the stoichiometric ratio of Me:V in the vanadate structure. The Ni and Co vanadates 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 near 1.0. The operating voltage of these materials was in the range of 1.0 to 2.0 V. Lithium ion coin cells using LiCoO 2 coupled with the vanadates, were 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.