Synthesis of Hierarchical Three-Dimensional Vanadium Oxide Microstructures as High-Capacity Cathode Materials for Lithium-Ion Batteries

Hierarchical three-dimensional (3D) vanadium oxide microstructures, including urchin like microflowers, nanohorn-structured rnicrospheres, nanosheet-assembled microflowers, and nanosheets bundles, are successfully synthesized by a versatile template free solvothermal method. It is found that the concentration of the precursor (VOC2O4) solution has a significant effect on the morphologies of the products. As an example, the time-dependent phase and morphology evolution for the urchin-like vanadium oxide microflowers has been investigated in detail. Urchin like VO2 microflowers can be self-assembled within 2 h without using any surfactants. After calcination, the VO2 microflowers can be easily transformed to urchin-like V2O5 microstructures. The as-obtained V2O5 microflowers are highly porous with a specific surface area of 33.64 m(2) g(-1). When evaluated as a cathode material for lithium-ion batteries, the V2O5 sample delivers very high specific discharge capacity of 267 mA h g(-1) at a current density of 300 mA g(-1). Further, it also exhibits improved cycling stability The excellent electrochemical performance is attributed to multiple advantageous structural features, including the nanosized building blocks, high porosity, and the 3D hierarchical microstructures.