The effect of titanium on the lithium intercalation capacity of V2O5 thin films

The effect of Ti incorporation on lithium intercalation capacity of V2O5 thin films prepared by spin coating using metalorganic (MO) and inorganic sol-gel (SG) precursors on indium tin oxide coated glass substrates have been investigated. Earlier studies show that V2O5-TiO2 oxide system has a higher cyclic stability than V2O5. However, there is controversy concerning the capacity of these mixed phases. We observe that upon incorporation of 5% Ti in MO films the lithium intercalation capacity decreases from 47 mC/cm(2) to 27 mC/cm(2) while for the SG films, the capacity increases from 14 mC/cm(2) to 27 mC/cm(2). We attribute this difference in the lithium intercalation capacity of the 5% Ti doped V2O5 films prepared by MO and SG precursors to the variation in the nonstoichiometry and the particle size. We find that it is essential to have a critical V:O ratio to achieve high intercalation capacity. Any deviations from this critical V:O ratio leads to a decrease in capacity and films having similar nonstoichiometry have similar values of intercalation capacity and diffusion coefficient. (C) 2009 Elsevier B.V. All rights reserved.