Flowerlike vanadium sesquioxide: solvothermal preparation and electrochemical properties.

A novel 3D hierarchical flowerlike vanadium sesquioxide (V(2)O(3)) nano/microarchitecture consisting of numerous nanoflakes is prepared via a solvothermal approach followed by an appropriate heating treatment. The as-obtained nanostructured V(2)O(3) flower is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, and transmission electron microscopy (TEM) (or/and high-resolution TEM, HRTEM), and it is found that the V(2)O(3) flower is constructed by single-crystalline nanoflakes. Furthermore, it is demonstrated that the surface of the flowerlike V(2)O(3) material is composed of nanostructured pores, which derive from the adsorption/desorption of nitrogen, and that the pore-size distribution depends on the unique three-dimensional interconnection between nanoflakes and on their intrinsic properties. The electrochemical behavior of the V(2)O(3) flower for lithium-ion insertion/extraction in non-aqueous solution as well as the faradaic capacitance for pesudocapacitors in a neutral aqueous solution are also investigated. A reversible discharge capacity as high as 325 mA h g(-1) is obtained at a current density of 0.02 A g(-1) from a LiClO(4)/EC:DEC electrolyte solution (i.e. LiClO(4) in ethyl carbonate and diethyl carbonate). When used as the cathode material of pesudocapacitors in Li(2)SO(4), the flowerlike oxide displayed a very high initial capacitance of 218 F g(-1) at a current density of 0.05 A g(-1). We believe that the good performance of the flowerlike V(2)O(3) electrode is most probably due to its unique 3D hierarchical nano/microarchitecture, which shows that the electrochemical properties of a cathodic material do not only depend on the oxidation state of that material but also-to a large extent-on its crystalline structure and morphology. The aforementioned properties suggest that the present V(2)O(3) flower materials may have a great potential to be employed as electrode materials in rechargeable lithium batteries and pesudocapacitors.