Oxygen vacancies enhance lithium storage performance in ultralong vanadium pentoxide nanobelt cathodes

Ultralong V₂O₅ nanobelts have been successfully synthesized by a facile hydrothermal oxidation route. Oxygen vacancies are generated in the V₂O₅ nanobelts by annealing under N₂ atmosphere at an elevated temperature. The microstructure and chemical composition of the pristine and annealed V₂O₅ nanobelts are studied by different methods. Compared to the pristine V₂O₅ nanobelts, the annealed V₂O₅ nanobelts sample possesses a higher reversible capacity of 177.8 mAhg⁻¹ after 50 cycles at a current density of 0.3 Ag⁻¹, corresponding to ∼0.27% capacity loss per cycle. At a higher current density of 1.2 Ag⁻¹, the reversible capacity of annealed V2O5 electrode can reach 128.5 mAhg⁻¹, which is two times larger than that of pristine V₂O₅ electrode. Ultralong flexible morphology together with oxygen vacancies in the annealed V₂O₅ electrode is considered to be responsible for the enhanced lithium storage properties.