Bilayered vanadium oxide as the host material for reversible beyond lithium ion intercalation

Bilayered vanadium oxide has emerged as a high-performance cathode material for beyond lithium ion (BLI) battery systems including Na-ion batteries, Mg-ion batteries, and pseudocapacitors. The major structural feature of bilayered V2O5 that makes it attractive for such applications is its large interlayer spacing of ~10-13 Å. This spacing can be controlled via the interlayer content, which can consist of varying amounts of structural water and/or inorganic ions, resulting in numerous chemical compositions. Further, bilayered V2O5 can be synthesized via a number of different methods, resulting in morphologies that include xerogel, aerogel, thin films, and 1-D nanostructures. The interlayer spacing, content, and material morphology can all affect the electrochemical performance of this materials family, and in this review, we discuss the role of each of these factors in the reversible cycling of charge-carrying ions beyond lithium. The different bilayered V2O5 synthesis methods and res