Synthesis and Electrochemical Properties of Na and Mg co-Doped LiFe0.65Mn0.35PO4/C Cathode Materials for Lithium-Ion Batteries

In this paper, Li(LiFe0.65Mn0.35)(0.98)Mg0.02PO4/C, Li0.98Na0.02Fe0.65Mn0.35PO4/C and Li0.98Na0.02(Fe0.65Mn0.35)(1-x)MgxPO4/C (x = 0.01, 0.02, 0.03, 0.05) were successfuly synthesized by solgel method and modified by Na+ doped and Mg+ doped. The effects of Na+ and Mg+ doping on the structure, morphology and electrochemical performance of LiFe0.65Mn0.35PO4/C were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and electrochemical tests. The results show that when x=0.03, the material has the best electrochemical performance. The first discharge capacity at 0.1 C is as high as 147.7 mAhg(-1) (1 C=170.2 mAhg(-1)) at the potential range of 2.5-4.5 V, When returning to 0.1 C after 40 cycles, the discharge specific capacity is still up to 142.1 mAhg(-1). In addition, the Rct values and the Li+ diffusion coefficient of Na0.02Mg0.03 were 215.2 Omega, 4.501 x 10(-14) cm(2) s(-1), respectively.