Effects of nickel-doped lithium vanadium phosphate on the performance of lithium-ion batteries

In this paper, a facile and cheap innovative way to reduce the cost and improve the vanadium utilization of Li3V2(PO4)3 (LVP) was introduced, and a series of nickel (Ni)-doped LVP (LVPN-x) composites as novel cathode materials used in lithium-ion batteries were synthesized by microwave assisted sol–gel method. The structures and morphologies of the as-prepared samples were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The Ni doping contents on the electrochemical properties of the as-prepared samples were investigated by galvanostatic charge/discharge, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and linear polarization curve (LPC), respectively. Among all the samples, the LVPN-x composites with the Ni doping amount of 1 wt.%, demonstrated a high discharge capacity and good rate capability. The material showed a reversible discharge capacity of 128 and 114 mAh g−1 at 0.1 and 2 C. The good electrochemical performance of LVPN-1 wt.% was attributed to its monoclinic structure and uniform distribution, which provided a large exchange current density (J0) of 1.532 mA cm−2 and a smaller charge transfer resistance, and this is favorable for the insertion/extraction of Li+. These results indicate that the as-prepared LVPN-1 wt.% material has potential to be a promising candidate as large capacity and high power cathode material in the next generation lithium-ion batteries.

► LVPN-x composite materials were synthesized by microwave assisted sol–gel method.
► The Ni-doped LVP displays better electrochemical performances.
► Linear polarization curve was identified in the over potential range of −5 to 5 mV.
► Variation of technical performance was analyzed to optimize the Ni doping content.