Abstract:2LiFe_1-xCo_xPO₄-Li₃V₂(PO₄)₃/C was synthesized using Fe_1-2xCo_2xVO₄ as precursor which was prepared by a simple co-precipitation method. 2LiFe_1-xCo_xPO₄-Li₃V₂(PO₄)₃/C samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements. All 2LiFe_1-xCo_xPO₄-Li₃V₂(PO₄)₃/C composites are of the similar crystal structure. The XRD analysis and SEM images show that 2LiFe_0.96Co_0.04PO₄-Li₃V₂(PO₄)₃/C sample has the best-ordered structure and the smallest particle size. The charge-discharge tests demonstrate that these powders have the best electrochemical properties with an initial discharge capacity of 144.1 mA·h/g and capacity retention of 95.6% after 100 cycles when cycled at a current density of 0.1C between 2.5 and 4.5 V.

Key words: LiFePO₄; Li₃V₂(PO₄)₃; Co doping; lithium-ion batteries