Preparation and electrochemical performance of 2LiFe1-xCoxPO4-Li3V2(PO4)3/C cathode material for lithium-ion batteries

2LiFe1-xCoxPO4-Li3V2(PO4)3/C was synthesized using Fe1-2xCo2xVO4 as precursor which was prepared by a simple co-precipitation method. 2LiFe1-xCoxPO4-Li3V2(PO4)3/C samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements. All 2LiFe1-xCoxPO4-Li3V2(PO4)3/C composites are of the similar crystal structure. The XRD analysis and SEM images show that 2LiFe0.96Co0.04PO4-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.