V2O5 nanocrystals: Chemical solution synthesis, hydrogen thermal treatment and enhanced rate capability as cathode materials for lithium-ion batteries

• V 2 O 5 nanocrystals with an elongated plate-like morphology are prepared. • Oxygen vacancies are present in samples annealed under hydrogen-containing gases. • An initial capacity of 284 mAh g −1 and a capacity of 153 mAh g −1 at 10 C are obtained. • Enhanced rate capacity and cycling stability are observed on the annealed samples. Vanadium pentoxide (V 2 O 5 ) is regarded as a promising cathode material for high-performance lithium-ion batteries (LIBs). In this study, V 2 O 5 nanocrystals with an elongated plate-like morphology are prepared via a chemical solution approach that involves the hydrolyzation of vanadyl sulfate in alkaline solution. Oxygen vacancies are intentionally created by thermal treating the V 2 O 5 samples under hydrogen-containing gases at different temperatures. Although the annealing process does not change the shape, morphology and crystalline structure of V 2 O 5 nanocrystals, it does bring about a small amount of oxygen vacancies, as evidently from the results of XRD patterns and Raman spectra. The presence of oxygen vacancies has positive effects on the electrochemical properties. A higher initial discharge capacity, and excellent rate capability and cycling stability are observed on the oxygen vacancy-containing V 2 O 5 samples. Especially, the sample annealed at 350 °C is found to have an initial capacity of 284 mAh g −1 and the capacity still maintains at about 153 mAh g −1 even at 10 C. The combination of nanoscale dimension and oxygen vacancies in V 2 O 5 nanocrystals presents a simple way to improve their rate capability and cycling stability for potential high-performance LIB applications.