β-NaVO3 as a pseudocapacitive anode material for sodium-ion batteries†
Abstract
High-performance anode materials are essential for the realization of sodium-ion batteries. In this work, nanostructured orthorhombic β-NaVO3 was prepared by a simple solution method and investigated as an anode material for sodium-ion batteries. β-NaVO3 exhibits an initial discharge capacity of 356 mA h g−1 at a low current density. Enhanced performance was realized with the β-NaVO3/Gr composite with an initial discharge capacity of 576 mA h g−1 at a low current density and an excellent cycle stability of 83% capacity retention after 400 cycles at a current density of 500 mA g−1. The sodium diffusion coefficients of β-NaVO3/Gr and β-NaVO3 calculated by the galvanostatic intermittent titration technique vary from 10−13 to 10−10 cm2 s−1. Ex situ XRD, TEM and Raman results reveal that the orthorhombic crystal structure of β-NaVO3 transforms into an amorphous phase after the initial charging–discharging process. The detailed pseudocapacitive behavior in β-NaVO3 was investigated by cyclic voltammetry.