Lithium intercalation in nanostructured thin films of a mixed-valence layered vanadium oxide using an ionic liquid electrolyte

Nanostructured thin films of a mixed-valence, layered vanadium oxide were prepared using layer-by-layer deposition. The thin films were characterized by electronic (UV–vis) spectroscopy, quartz crystal microbalance, profilometry and scanning electron microscopy techniques. The highest charge capacity was obtained for films that consisted of 25 bilayers. The electrochemical characterization of the films was performed in conventional organic solvent and ionic liquid (IL) based electrolytes. The results revealed better performance, in terms of stability during consecutive charge/discharge cycles, when ILs were employed. This can be attributed to several factors, including reduced mechanical stress caused by insertion of more than 1 mol of Li+ per mol of V5+ in the film structure, decrease of crystallinity in the electrode material during the first few charge/discharge cycles and/or formation of a more compatible SEI. Nanostructured thin films of layered vanadium oxide prepared using layer-by-layer deposition showed potential for applications in lithium microbatteries. ► Thin films of vanadium oxide were prepared by layer-by-layer deposition. ► Film growth were analyzed by kinetic and isothermal approaches. ► Good initial capacity were obtained in organic solvent and ionic liquid electrolytes. ► Better capacity retention was obtained in ionic liquid electrolyte.