Simple microwave synthesis and improved electrochemical performance of Nb-doped MnO2/reduced graphene oxide composite as anode material for lithium-ion batteries

Niobium-doped MnO 2 /reduced graphene oxide (Nb-MnO 2 /RGO) composite has been successfully synthesized via a simple microwave radiation method. The samples were systematically studied by X-ray diffraction (XRD), thermogravimetric analysis (TG), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), and electrochemical measurements. As the anode material for lithium-ion batteries, the Nb-MnO 2 /RGO (molar ratio of Mn/Nb = 50:1) (NMG50) showed an outstanding reversible discharge capacity of 556.6 mAh g −1 after 50 cycles with a capacity retention of 77% at a charge-discharge rate of 0.1 A g −1 and the reversible discharge capacity can still retain 223.3 mAh g −1 at a current of 1 A g −1 , which is much higher than those for Nb-MnO 2 /RGO (molar ratio of Mn/Nb = 10:1) (NMG10) and undoped MnO 2 /RGO (MG). The improved electrochemical performance could be attributed to the proper amount of Nb doping, which could enhance both the conductivity and the structure stability of MnO 2 .