▎ 摘　　要

A reduced graphene oxide loading iron-based fluoride (abbreviated as Fe2F5 center dot H2O/rGO) as a cathode material for sodium ion batteries (SIBs) has been successfully prepared by an ionic-liquid-assisted route. The morphology, structure, physicochemical properties and electrochemical performance are characterized by X-ray powder diffraction (XRD), Rietveld refinement of XRD pattern, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical tests. The XRD result shows that the crystal structure of the as-prepared sample can be indexed to the cubic Fd-3m space group and the lattice parameter is as follow: a = 1.04029 nm and V = 1.12581 nm(3). Moreover, the SEM and TEM images reveal that the as-prepared rGO has a rough wavy structure and flexural paper-like morphology, and numerous Fe2F5 center dot H2O particles are firmly adhered on the surface of the rGO to form an uniform Fe2F5 center dot H2O/rGO composite. Electrochemical tests show that the initial discharge capacity of Fe2F5 center dot H2O/rGO sample is 248.7 mAh g(-1) and the corresponding charging capacity up to 229.7 mAh g(-1) at a rate of 20 mA g(-1). Especially, the Fe2F5 center dot H2O/rGO possesses good cycling stability, and it can deliver a discharge capacity of 164.2 mAh g(-1) at the 100th cycle. Besides, the rate capability tests show that a stable high capacity of 186.0 mAh g(-1) can be resumed when the current rate returns to 20 mA g(-1) after 20 cycles. (C) 2016 Elsevier B.V. All rights reserved.