Single-Crystalline Bilayered V₂O₅ Nanobelts for High-Capacity Sodium-Ion Batteries

Single-crystalline bilayered vanadium oxide nanobelts were synthesized by a simple solvothermal method. FESEM and AFM analyses identified the nanobelt morphology of the as-prepared vanadium oxide with a rectangular cross-section and a thickness of approximately 50 nm. XRD and TEM characterizations revealed the presence of a large (001) interlayer spacing (∼11.53 Å), which can accommodate Na-ion insertion and extraction. When applied as cathode materials in Na-ion batteries, vanadium oxide nanobelts exhibited a high capacity of 231.4 mA h g(-1) at a current density of 80 mA g(-1). This corresponds to the theoretical capacity to form Na2V2O5 on Na-ion insertion. Vanadium oxide nanobelts also demonstrated an excellent high-rate performance and a satisfactory cyclability. These superior electrochemical performances could be ascribed to the unique bilayered vanadium oxide nanobelts with dominantly exposed {100} crystal planes, which provide large interlayer spacing for facile Na-ion insertion/extraction. Single-crystalline bilayered vanadium oxide nanobelts could be promising cathode materials for high-performance Na-ion batteries.