Sodium-ion batteries (SIBs) have received intensive attentions owing to the abundant and inexpensive sodium (Na) resource. Layered vanadium oxides are featured with various valence states and corresponding compounds, and through multi-electron reaction they are capable to deliver high Na storage capacity. The rational construction of unique structures is verified to improve their Na storage properties. This perspective provides an overview of recent advances in layered vanadium oxide for SIBs, with a particular focus on construction of novel nanostructures, and mechanism studies via in situ characterization. Finally, we predict possible breakthroughs and future trends that lie ahead for high-performance layered vanadium oxides SIBs cathode.

Vanadium oxide nanowires have gained increasing interest as the electrode materials for Li-ion batteries. This article presents the recent developments of vanadium oxide nanowire materials and devices in Li-ion batteries. First, we will describe synthesis and construction of vanadium oxide nanowires. Then, we mainly focus on the electrochemical performances of vanadium oxide nanowires, such as VO2, V2O5, hydrated vanadium oxides, LiV3O8, silver vanadium oxides, etc. Moreover, design and in situ characterization of the single nanowire electrochemical device are also discussed. The challenges and opportunities of vanadium oxide nanowire electrode materials will be discussed as a conclusion to push the fundamental and practical limitations of this kind of nanowire materials for Li-ion batteries.

This review represents recent research on using chemical prelithiation to improve cycling performance of nanostructured electrode materials for lithium ion batteries in our group. We focus on two typical cathode materials, MoO3 nanobelts and FeSe2 nanoflowers. Methods of direct or secondary hydrothermal lithiation of MoO3 nanobelts and FeSe2 nanoflowers are described first, followed by electrochemical investigation of the samples before and after lithiation. Compared with pristine materials, lithiated samples exhibit better cycling capability. Prelithiation of other kinds of materials, such as V2O5, MnO2, etc. is also briefly reviewed. This demonstrates that prelithiation can be a powerful general approach for improving cycling performance of Li-ion battery electrode materials.

Mo doped vanadium oxide nanotubes (VONT) were formed via a rheological phase reaction followed by self-assembling process and were heated at 400 □ in an inert atmosphere. The nanotubes were characterized by SEM, HRTEM, XRD, FTIR, electrochemical investigation, etc. In contrast to the undoped VONTs, the interlayer distance between oxide layers in the (V0.99Mo0.01)xONTs increases owing to replacement of some V in nanotubes by Mo with a larger ionic radius, resulting in a shorten diffusion length of Li ions and an improved electrochemical performance. The electrochemical performance of (V0.99Mo0.01)xONTs is further enhanced by removing the residual organic template by heating in an inert atmosphere.

Vanadium dioxide nanorods (B phase) have been synthesized, for the first time, using cetyltrimethylammonium bromide (CTAB) as structure-directing template in hydrothermal condition. Morphology and structure of the sample were characterized by XRD, SEM, HRTEM, XPS, TG-DTA and redox titration. The results show that the products are VO2 (B) nanorods and they are 1∼2 μm in length. HRTEM micrographs reveal that they indeed form bundles of agglomerated smaller filaments with diameters ranging from 20 to 40 nm. This filament-like shape in the nanoscale dimension leads to the exposure of a large fraction of the atoms to the surface. Thus, these materials are promising candidates for the development of new functionalized materials. TG investigation shows that there are a weight loss of 2.21 % between 250∼400 °C corresponding to removal of the organic residuals and a weight gain at about 430 °C corresponding to oxidation of vanadium with low oxidation state. The simplicity of hydrothermal process, cheapness, and availability of raw materials are advantages favoring the scaling-up of nanorods.