Large-scale preparation of single-crystalline V2O5 nanobelts is successfully demonstrated with a simple solution treatment process under ambient condition using commercial V2O5 powders as the precursor. Unlike the commonly recognized Ostwald ripening process that involves the dissolution of small crystals and the redeposition of the dissolved species on the more energetically favored large particles, this preparation shows that the reaction mechanism of our method follows a different route, in which the large commercial V2O5 powders (1–4ÎŒm) dissolve in the solution and eventually transform into V2O5 nanobelts with lengths up to several tens of micrometers, widths of 5–50nm, and thicknesses of only 5nm. The density function theory (DFT) calculation indicates that the preferential growth of V2O5 nanobelts along the [010] direction is attributed to the anisotropic bonding of V2O5 layered structure resulting in the fastest nucleation rate at the V2O5(010) surface. These nanobelts possess a remarkably large surface area, which is about 14 times higher than that of the V2O5 precursor. Binder-free bulky papers can be prepared by the intertwining V2O5 nanobelts with the acid-treated multi-walled carbon nanotubes. When the V2O5 nanobelts are applied as the cathodes in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), such robust and flexible electrodes demonstrate superior lithium and sodium storage performances at fast charge/discharge rates, delivering 144mAhg−1 at 20C in LIBs and 61mA h g−1 at 10C in SIBs respectively.