High Li<sup>+</sup>-Ion Storage Capacity and Multi-Electrochromism Behavior of Electrodeposited Molybdenum Doped Vanadium Oxide Films

Molybdenum doped vanadium oxide (Mo doped V2O5) xerogel films were prepared by cathodic electrodeposition on indium tin oxide (ITO) substrate from Mo doped V2O5 sol synthesized by sol-gel combined with hydrothermal reaction. Mo doped V2O5 xerogel films were deposited at different potentials between -0.01 V and -0.7 V vs saturated calomel electrode (SCE) with the potentiostatic mode. The structure was characterized for using X-ray diffraction (XRD), atomic force microscopy (AFM). These studies reveal that films consist of layered V2O5 host structure with various surface morphologies depending upon the deposition potentials. As shown by the cyclic voltammograms results, the films electrodeposited at -0.3 V exhibited Li+-ion storage capacity as high as ca. 70 mC/cm2 for the 50th cycle and showed multi-electrochromic behavior (orangered-green-blue) depending on the extent of intercalation during the electrochemical lithium insertion/extraction processes. It is proposed that the particles forming the films arrange directionally and crystallize partly, which lead to the enhanced electroactivity of vanadium oxide films by shortening the diffusion distance or quickening the transference rate of Li+ ions in the films.