The improved cycling stability and rate capability of Nb-doped NaV3O8 cathode for sodium-ion batteries.

• NVO material doped by niobium ion (Nb5+) was successfully prepared by the rheological phase method. • Nb-doping lead to an expansion of the lattice volume and increase the intrinsic conductivity. • NaNb 0.018 V 2.982 O 8 demonstrates high-rate capability and long-term cyclability. • Pseudocapacitive behavior of Nb-doped NVO is confirmed by kinetics analysis. In this work, NaNb 0.018 V 2.982 O 8 (NVO-0.018Nb) composite was served as the cathode of sodium-ion batteries (SIBs) to deliver a superior Na-storage capacity of 187 mA h g−1 at the current density of 1 C and voltage range of 1.5–4.0 V, and favorable energy density (419.3 Wh kg−1). Electrochemical impedance spectroscopy (EIS) measurements displayed decreased charge transfer resistance in the NVO-0.018Nb composite. The detailed kinetic analysis revealed enhanced surface-controlled behaviors, leading to improved sodium-storage capability. Scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) analyses demonstrated that NVO-0.018Nb composite exhibited unique structure with significantly enhanced structural stability during fast cycling. In sum, the proposed method looks promising for the design of future advanced electrode materials of SIBs. [ABSTRACT FROM AUTHOR]