Deoxidization of V2 O5 Powder into VO2 Assisted by an Electrochemical Lithium Intercalation Technique.

This article demonstrates a method to fabricate VO₂ powder by annealing a precursor that was obtained by electrochemical intercalation of lithium into layered structured V₂ O₅. The method includes three steps. First, Li⁺ was intercalated into interlayers of V₂ O₅ through an electrochemical process with precisely controlled electrical discharging currents and intercalation amounts, and at the same time V⁵⁺ would be deoxidized into V⁴⁺. Secondly, the Li⁺-intercalated powder was rinsed in an acid solution to achieve an ion exchanging process of replacing the Li⁺ in the V-O frame with H⁺. Thirdly, the powder was annealed at 800°C in N₂ atmosphere for dehydration and VO₂ crystallization. By DSC investigation, the as-produced final product has a strong endothermic peak at around 68°C in a heating semicycle, which is indicative of the phase transition from VO₂( M) to VO₂( R). This approach can be extended to the fabrication of other sub-valence oxides by lithium intercalation and deoxidization of its higher valence layer-structured precursors. [ABSTRACT FROM AUTHOR]