Preparation and characterization of LiFePO4/C composite doped with various metals

Nanosized spherical FePO4·2H2O precursor was synthesized via ultrasonic-aided precipitation route. LiFePO4/C composites doped with various metals were prepared by carbothermal reduction. The phases, structures and the morphologies of FePO4·2H2O and LiFePO4/C were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), charging and discharging measurements, cyclic voltammogram (CV) testing and electrochemical impedance spectra (EIS). The results show that nanosized spherical FePO4·2H2O are prepared with uniform distribution when the solution concentration is 0.1 mol/L. The discharge capacity and lithium ion diffusion rate are increased by doping various metals. Especially, LiFePO4/C composites made from nanosized spherical FePO4·2H2O precursor doped with Ni and Nb shows excellent electrochemical performance. It delivers an initial discharge capacity of 158.8 mAh/g at 0.1C rate and 150.2 mAh/g at 1C rate, and capacity retention is 98.3% and 97.8%, respectively, after 100 cycles. Copyright © 2014 Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved.