Electrochemically Anodized V2O5 as an Efficient Sodium Cathode

Vanadium oxide has a high theoretical capability for sodium storage, but this capability has often been plagued by sluggish electrochemical reaction kinetics upon sodiation/desodiation. To alleviate this problem, we report on an ordered structure of V2O5 nanopores by electrochemical anodization. The nanopores are amorphous in structure, 30-40 nm in diameter, and similar to 2.4 mu m in depth, exhibiting favorable electrochemical performance for sodium. In the potential range between 1.5 and 3.8 V, the nanoporous architecture of V2O5 displays a reversible capacity of 177 mAh g(-1) with initial coulombic efficiency of 74% and retains a capacity of 69 mAh g(-1) over 50 cycles at a higher rate of 100 mA g(-1). The open framework of nanopores and the isotropic properties of the amorphous structure are believed to be responsible for the appealing electrochemical performance of anodized V2O5.