Synthesis and Li+ intercalation/extraction in ultrathin V2O5 layer and freestanding V2O5/Pt/PVA multilayer films

A uniform V2O5 nanostructured ultrathin film has been prepared by spin-coating followed by heat treatment. This V2O5 nanostructured ultrathin film is composed of 4 nm closely connected V2O5 domains and has lamellar structure. Compared with a thicker V2O5 film (78 nm), the 17 nm V2O5 film showed a very good electrochemical performance of fast charge/discharge and excellent electrochemical stability. The excellent electrochemical performance of the V2O5 nanostructured ultrathin film is attributed to its nanostructure, which results in short Li+ diffusion distance and free Li+ accessibility to intercalation active sites. A facile approach to preparing a freestanding V2O5/Pt/PVA multilayer film on a large scale was developed. The thicknesses of the V2O5, Pt, and PVA are 22, 57, and 704 nm, respectively. The freestanding multilayer is stable in air, flexible, and robust and exhibits excellent electrochemical performance.