Effects of Transiotion Metal Co-Doping on the Electrochemical Properties of Li3V2-2xFexMnx(PO4)3/Graphene Cathode Material for Lithium Secondary Battery

Tuesday, October 13, 2015
West Hall 1 (Phoenix Convention Center)
H. S. Kim, M. Jeong (Osaka National University), and B. S. Jin (KERI)
A series of Fe and Mn co-doped Li3V2–2xFexMnx(PO4)3/graphene (x = 0, 0.005, 0.010, 0.015, 0.020, and 0.025) samples have been fabricated via a sol-gel assisted microwave synthesis method. The crystal structure and morphology of the synthesized Li3V2–2xFexMnx(PO4)3/graphene was investigated using an X-ray diffraction (XRD) and a scanning electron microscopy (SEM) systematically. Electrochemical measurement results prove that the Li3V1.98Fe0.01Mn0.01(PO4)3/graphene sample presents the best electrochemical performance as the cathode material for lithium ion batteries among the as-prepared samples in the potential ranges of 3.0–4.8 V. The resulting Li3V1.98Fe0.01Mn0.01(PO4)3/graphene cathode has an excellent specific capacity of 184.4 mAh g−1 at 0.1C rate, and even at 10C rate, it still delivers the specific capacity of 110.5 mAh g−1. The substitution of V3+ with an appropriate amount of Fe2+ and Mn4+ increases the Li+ diffusion coefficient assuming from the electrochemical impedance spectroscopy results, which is mainly responsible for the excellent electrochemical performance.