Hydrothermal preparation and intrinsic transport properties of nanoscale Li2FeSiO4

摘要

Nanoscale Li2FeSiO4 cathode material is successfully prepared using a ball-milling assisted hydrothermal method with inorganic precursors. Structures, morphologies, and thermal stabilities of the samples are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric-differential scanning calorimetry (TG-DSC). The prepared Li2FeSiO4 samples are well crystallized and have an irregular cuboid morphology with particle sizes in the range of 50-300 nm. The crystal structure of pure Li2FeSiO4 is stable in air at room temperature, and no distinct new phase is observed for the sample annealed at 300 degrees C in argon. The temperature-dependent intrinsic transport properties of nanoscale Li2FeSiO4 are obtained using dynamic potential scanning (DPS) and electrochemical impedance spectroscopy (EIS); the ionic conductivity and electronic conductivity are 1.32 x 10(-8)S/cm and 2.8 x 10(-8) S/cm, respectively, at 20 degrees C. Nanoscale Li2FeSiO4 exhibits stable cycle performance at different rates from 0.1C to 2C, and at 0.1C its specific charge and discharge capacity remain 144.1 rnAh/g and 138.8 mAh/g, respectively, after 50 cycles.