Influence of stoichiometry of V$_{2}$O$_{5}$ thin films on the electrochemical properties

V$_{2}$O$_{5}$ has been widely used in a variety of technological applications such as solid state battery cathodes, solar cell windows, and electrochromic devices, as it allows easy intercalation/deintercalation of different ions due its open layered structure. However, the electrochemical properties of V$_{2}$O$_{5}$ critically depend on the details of its composition, and preparation methods, thus requiring optimization of several growth parameters. We present experimental results on the effect of V$_{2}$O$_{5}$ stoichiometry on electrochemical characteristics, including the intercalation capacity and Li$^{+}$ diffusion coefficient. We have prepared V$_{2}$O$_{5}$ thin film samples with different stoichiometry by spin coating with three precursors of different carbon to vanadium ratio: (i) a sol gel inorganic,(ii) a sol-gel organic , and (iii) a metalorganic precursor. The stoichiometry of V$_{2}$O$_{5 }$is found to be very sensitive to carbon to vanadium ratio in the precursor. Films prepared from the metalorganic precursor, with a high carbon to vanadium ratio, are highly non-stoichiometric, as determined using Raman and UV-visible spectroscopy and high resolution electron microscopy and possess a higher intercalation capacity and a larger Li$^{+}$ diffusion coefficient.