Vanadium Dioxide Reduced Graphene Oxide Composite As Cathode Materials for Rechargeable Li and Na Batteries

Abstract

In recent years, new cathode materials have been intensively investigated, as the demand for rechargeable batteries are increasing with the rapid growth of technology for electronic devices and electric vehicles. Among them, metastable form of vanadium dioxide, denoted as VO2(B), has gained great interest owing to its electrode potential and its tunnel structure which is ideal for ions intercalation/deintercalation. In this study, VO2(B)]modified with and without reduced graphene oxide (rGO) were synthesized via solvothermal method. The obtained products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). X-ray diffraction study reveals that the electrochemical reaction of VO2(B)/rGO is progressed based on deintercalation and intercalation of alkali ions (Li+ and Na+) into and out of the crystal structure; this is caused by the presence of open channels in the crystal structure of VO2(B). As a result, the resulting electric conductivity of the VO2(B)/rGO composite is improved to ~10-4 cm S-1 (from ~10-7 S cm-1 for the as-received VO2(B)). Electrochemical data of the VO2(B)/rGO composite, tested in both Li and Na cells, shows markedly enhanced electrochemical performance compared to bare VO2(B). The effect of electro-conducting rGO is more evident at high rates. The results show that solvothermally synthesized VO2(B)/rGO composite can be a potential cathode material for rechargeable batteries.