Synthesis of hierarchical three-dimensional vanadium oxide microstructures as high-Capacity cathode materials for lithium-ion batteries

Abstract

Hierarchical three-dimensional (3D) vanadium oxide microstructures, including urchin-like microflowers, nanohorn-structured microspheres, 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 m2 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.