Graphene oxide assisted preparation of V₂O₅ films for electrochromic and energy storage applications

A V2O5 film is prepared by an electrochemical deposition method with the assistance of graphene oxide (GO). The surface morphology and microstructure of the film are characterized by scanning electron microscope, X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy measurements. The results demonstrate that the prepared film is mainly composed of orthorhombic alpha-V2O5 with a small amount of tetragonal beta-V2O5; the V2O5 film has a wrinkled surface morphology and contains a certain low valance V4+ and a trace amount of graphene oxide residue. The V2O5 film exhibits good lithium storage activity and excellent cycling stability (with a capacity retention rate of 93.6% after 500 cycles at 0.5 mA cm(-2)). During lithium intercalation and de-intercalation processes, the color of the V2O5 film changes reversibly from yellow to green, and finally blue, with a fast response time (6 similar to 9 s) and high coloration efficiency (19.77 cm(2) C--(1)). In addition, the electrochromic device assembled with the V2O5 film as the electrochromic layer, NiHCF as the ion storage layer, and 1 M LiClO4/propylene carbonate solution as the electrolyte also exhibits excellent cycling stability, suggesting the significant potential of this V2O5 film for electrochromic and energy storage applications.