Synthesis and electrochemical properties of Mg-doped and Al-doped LiMnPO4•Li3V2(PO4)3/C cathode materials for lithium-ion batteries

In this paper, LiMn1-xMgxPO4Li3V2(PO4)(3)/C (x=0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.10) and LiMnPO4Li3V2-yAly(PO4)(3)/C (y=0.01, 0.02, 0.03, 0.05, 0.07, 0.10) composite cathode materials for lithium-ion batteries were successfully synthesized by a simple sol-gel method and modified by Mg2+ doped and Al3+ doped. The effects of Mg2+ and Al3+ doping on the microstructure and electrochemical properties of LiMnPO4Li3V2(PO4)(3)/C were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), EDAS energy spectrum analysis (EDS), constant current charge/discharge electrical test, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The analysis shows that the electrochemical properties of samples have been greatly improved. The results show that when x=0.06 and y=0.02, the material has the best electrochemical performance. Under the voltage range of 2.5-4.5V, the initial discharge specific capacity at 0.1C (1C=143mAhg(-1)) is as high as 148.2mAhg(-1) and 134.4mAhg(-1), respectively.