Preparation and electrochemical performance of Gd-doped LiFePO4/C composites

In this paper, LiFe1−xGdxPO4/C composites (x = 0, 0.02, 0.04, 0.06, 0.07, 0.08) are synthesized via a high-temperature solid-phase reaction. The structure and electrochemical behavior of the materials are investigated using a wide range of techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), particle size analysis, galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS). It is found that the maximum discharge capacity of the as-prepared LiFe0.93Gd0.07PO4/C composite can reach up to 150.7 mAh g−1, 125.9 mAh g−1, 106.0 mAh g−1 and 81.3 mAh g−1 at rates of 0.2 C, 1 C, 5 C and 10 C, respectively. And at 0.1 C rate, the initial discharge capacity of the composite monotonically increases with temperature from 66.3 to 122.2 mAh g−1 in the range of −30 to 0 °C. It is also demonstrated that the presence of a small amount of Gd3+ ion in the sample prepared in this work can reduce the charge-transfer resistance, resulting in the enhanced electrochemical catalytic activity.

► LiFe1−xGdxPO4/C (x = 0–0.08) composites have been synthesized first.
► We test the discharge capacity of LiFe0.93Gd0.07PO4/C at lower temperatures.
► Doping Gd3+ ion improve the electrochemical catalytic activity of LiFePO4/C.