Synthesis and electrochemical performances of (1−x)LiMnPO4·xLi3V2(PO4)3/C composite cathode materials for lithium ion batteries

A series of (1−x)LiMnPO4·xLi3V2(PO4)3/C (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 1) composites cathode materials are successfully synthesized by solid-state method. The structures and properties of the composites have been studied with X-ray diffraction (XRD), scanning electron microscopy (SEM), elemental mapping, high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS) and electrochemical measurements. XRD results reveal that the composites comprise Li3V2(PO4)3 phase and LiMnPO4 phase with a small amount of LiVP2O7 impurity. The electrochemical measurement results show that the ratios of LiMnPO4 to Li3V2(PO4)3 are correlated with the electrochemical performances of the composite materials. Among these composites, the 0.6LiMnPO4·0.4Li3V2(PO4)3 exhibits the best electrochemical performance, it can deliver specific capacity of 154 mA h g−1 at 0.05 C charge-discharge rate.