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−xMgxPO4·Li3V2(PO4)3/C (x = 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.10) and LiMnPO4·Li3V2−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 LiMnPO4·Li3V2(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 2.5–4.5 V, the initial discharge specific capacity at 0.1 C (1 C = 143 mAh g−1) is as high as 148.2 mAh g−1 and 134.4 mAh g−1, respectively.