Integration of NaV6O15·nH2O nanowires and rGO as cathode materials for efficient sodium storage

The NaV6O15·nH2O (NVO·nH2O) nanowires are wrapped by reduced graphene oxide (rGO) layers via facile one-pot hydrothermal method to construct electrode materials with 3D nanostructure for sodium ion batteries. The inserted sodium ion and water molecules could enlarge interlayer distance of V2O5, which realize fast sodium ion diffusion, further improving the sodium storage property. According to the electrochemical performance and corresponding analysis, the rGO layer not only prevents NVO·nH2O from dissolution in the electrolyte, but also enhances the electron and ion transport, which ensures high rate property and cycling stability. Benefiting from the sodium ion and water molecule insertion and protective rGO layer, the rGO/NVO·nH2O exhibits significantly improved electrochemical performance. Most importantly, the kinetics analysis demonstrates that the surface pseudocapacitance is the dominant contribution to capacity.