Hydrothermal preparation and intrinsic transport properties of nanoscale Li2FeSiO4

Abstract

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 °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 × 10−8 S/cm and 2.8 × 10−8 S/cm, respectively, at 20 °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 mAh/g and 138.8 mAh/g, respectively, after 50 cycles.