Abstract: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 ℃ 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.

Key words: lithium-ion battery; cathode material; LiFePO₄; Ti⁴⁺-doping; co-precipitation