Li-storage of Fe_3O_4/C composite prepared by one-step carbothermal reduction method

摘要

The Fe_3O_4/C is prepared by novel and cost effective carbothermal reduction method from commercial Fe_2O_3 and characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high reso lution-transmission electron microscopy (HR-TEM). Li-storage behaviour of Fe_3O_4/C has been evaluated by galvanostatic discharge-charge cycling and cyclic voltammetry (CV) in cells with Li-metal as counter electrode in the range of 0.005-3.0 V at ambient temperature. Results show that a high initial first cycle reversible capacity of 910 (±10) mA h g~(-1) (～7.9 mol of Li per mole of Fe_3O_4) is achieved when cycled at 60 mAg~(-1) and remained as 740 (±10) mA h g~(-1) (～6.43 mol of Li) at the end of 60 cycles. In this material, conductive carbon introduced during synthesis not only adds to the conductivity to the composite, but also alleviate the volume change during cycling. The Coulombic efficiency is found to be >96% in the range of 10-60 cycles. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are carried out to complement the galvanostatic cycling data. The experimental results suggest that composite Fe_3O_4/C has the potential to provide large and almost stable capacity for practical applications, and good opportunity for large scale synthesis using Fe_2O_3 , which is commercially available.