GeO₂ decorated reduced graphene oxide as anode material of sodium ion battery

GeO₂-reduced graphene oxide (RGO) composites were prepared by a simple freeze-drying method. After thermal annealing in N₂ atmosphere at 450 °C for 2 hours, the composites were examined as anode materials of sodium ion batteries for the first time. Their morphology, structure and electrochemical performance were characterized by field-emission scanning electron microscopy, X-ray diffraction, N₂ adsorption-desorption isotherm, cyclic voltammetry and electrochemical impedance spectroscopy, respectively. A maximum specific capacity of 330 mAh g^-1 can be achieved after 50 galvanostatic charge-discharge cycles at a current density of 100 mA g^-1 by tuning the RGO content in the composites. Even after 650 cycles at a high current density of 1 A g^-1, the specific capacity can still maintain at 153.7 mAh g^-1, demonstrating the excellent Na ion storage properties of the GeO₂-RGO composites.