Novel synthesis of LiMnPO4·Li3V2(PO4)3/C composite cathode material

Abstract

A carbon-coated LiMnPO₄·Li₃V₂(PO₄)₃ composite cathode material is synthesized from a rod-like MnV₂O₆·4H₂O precursor prepared via aqueous precipitation for the first time, followed by chemical reduction and lithiation with oxalic acid as the reducing agent and glucose as the carbon source. XRD results indicate that orthorhombic LiMnPO₄ and monoclinic Li₃V₂(PO₄)₃ co-exist. SEM results reveal that the thickness of the rod-like MnV₂O₆·4H₂O precursor is about 80 nm and that the LiMnPO₄·Li₃V₂(PO₄)₃/C composite possesses a micro/nano sphere-like morphology. HRTEM results indicate that the sample is a core–shell structure, where the external shell is amorphous carbon and at the core of the sample are LiMnPO₄, Li₃V₂(PO₄)₃ and LiMnPO₄·Li₃V₂(PO₄)₃ unit cells. The initial discharge capacity of the LiMnPO₄·Li₃V₂(PO₄)₃/C composite is 110 mA h g⁻¹, 104.4 mA h g⁻¹, 100.6 mA h g⁻¹ and 80.4 mA h g⁻¹ at the rate of 0.1 C, 1 C, 3 C and 10 C, respectively. The cell shows excellent cycling stability and good rate capability as a cathode for lithium-ion batteries.