Ambient dissolution-recrystallization towards large-scale preparation of V₂O₅ nanobelts for high-energy battery applications

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 (1-4 μm) dissolve in the solution and eventually transform into V₂O₅ nanobelts with lengths up to several tens of micrometers, widths of 5-50 nm, and thicknesses of only ~5 nm. 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 144 mA h g^-1 at 20 C in LIBs and 61 mA h g^-1 at 10 C in SIBs respectively.