Electrochemical performance of Ti4+-doped LiFePO4 synthesized by co-precipitation and post-sintering method

Ti4+-mixed FePO4·xH2O precursor was prepared by co-precipitation method, with which Ti4+ cations were added in the process of preparing FePO4·xH2O to pursue an effective and homogenous doping way. Ti4+-doped LiFePO4 was prepared by an ambient-reduction and post-sintering method using the as-prepared precursor, Li2CO3 and oxalic acid as raw materials. The samples were characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD), electrochemical impedance spectroscopy (EIS), and electrochemical charge/discharge test. Effects of Ti4+-doping and sintering temperature on the physical and electrochemical performance of LiFePO4 powders were investigated. It is noted that Ti4+-doping can improve the electrochemical performance of LiFePO4 remarkably. The Ti4+-doped sample sintered at 600 °C delivers an initial discharge capacity of 150, 130 and 125 mA·h/g with 0.1C, 1C and 2C rates, respectively, without fading after 40 cycles.