Synthesis and performance of high tap density LiFePO 4/C cathode materials doped with copper ions

Abstract

Stoichiometric Cu-doped lithium ion phosphate LiFe 1− x Cu x PO 4/C ( x = 0, 0.01, 0.015, 0.02, 0.025) cathode materials with a high tap density were synthesized by a solid state high temperature reaction in an inert atmosphere using Cu(Ac) 2 as a dopant and FePO 4 as a precursor. The synthesized LiFe 1− x Cu x PO 4/C powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical performance testing. The results indicate that the doped composite cathode materials are well crystallized with a typical homogeneous olivine-type structure. Materials with this olivine-type structure normally have a high crystallinity and high tap density. The tap density of LiFe 0.98Cu 0.02PO 4/C powders reached 1.98 g cm −3. Charge–discharge test showed that the cathode materials possessed the excellent charge/discharge capacities, about 150 mAh g −1 and 297.0 mAh cm −3 at a rate of 0.1 C and more than 127.3 mAh g −1 and 252.1 mAh cm −3 at a rate of 2 C.