Preparation and electrochemical performance of LiFePO_4-x F _x /C nanorods by room-temperature solid-state reaction and microwave heating

LiFePO_4-x F _x /C nanorods were prepared by room-temperature solid-state reaction and microwave heating. The structure and morphology of the as-prepared materials were analyzed by X-ray diffractometry and transmission electron microscopy. The results shows that the LiFePO _4-x F _x /C were well crystallized and consisted of nanoparticles with an average diameter of ten to several tens of nanometers, many round grains constituted solid rod-like structure. The length of the rods can be up to several hundreds of nanometers, and their diameters are around 100 nm. The results of electrochemical testing show that the initial discharge capacity of LiFePO_3.85F_0.15/C is 124.7 mAh g^-1, with a negligible fading after 50 cycles at a constant current density of 1 C at room temperature. The capacity retention rate is 99.5 %, which is higher than that of LiFePO₄/C prepared by the same method. The doping of F helps improve electrical conductivity and Li⁺ diffusion of LiFePO ₄/C. This study may provide new insights and understanding on the effect of F-doping on the electrochemical performance of LiFePO₄/C. © 2012 Springer Science+Business Media B.V.