Preparation and sodium storage performance of V2O5•nH2O/graphene composites

V2O5 center dot nH(2)O/graphene composites have been fabricated via a facile sol-gel method followed with an annealing treatment in air. The influence of incorporation of graphene on the microstructure and sodium storage performance of V2O5 center dot nH(2)O were investigated. XRD, Raman, and TGA analyses validated that graphene was successfully incorporated in V2O5 center dot nH(2)O particles; XPS tests revealed that the incorporation of graphene induced more V4+ in the V2O5 center dot nH(2)O. When evaluated as cathode materials for sodium-ion batteries (SIBs), the V2O5 center dot nH(2)O/graphene composites exhibited higher sodium storage capacity, better rate capability, enhanced Na+ diffusivity, and lower electrochemical reaction resistance as compared to the pure V2O5 center dot nH(2)O. However, the incorporation of graphene had no improvement of the cycling stability of V2O5 center dot nH(2)O. Ex situ XRD demonstrated that the layered structure of V2O5 center dot nH(2)O collapsed upon cycling, which accounts for the capacity decay of the samples.