Synthesis of vanadium doped LiMnPO4 by an improved solid-state method

Abstract A series of LiMn 1− x V x PO 4 /C (0≤ x ≤0.075) samples are synthesized via an improved solid-state method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. XRD, XPS and cyclic voltammetry (CV) tests reveal that olivine phase is observed exclusively in LiMn 1− x V x PO 4 /C (0≤ x ≤0.05) samples and the valence of the doped V is +3, whereas a minor amount of Li 3 V 2 (PO 4 ) 3 is additionally detected in the LiMn 1− x V x PO 4 /C at x =0.075. SEM observation shows that much smaller crystals of V-doped LiMnPO 4 can be obtained at relatively high temperatures by our synthesis method and consequently more vanadium can be incorporated into the lattice of LiMnPO 4 . Electrochemical test demonstrates that a proper amount of V doping on the Mn-site in LiMnPO 4 can effectively enhance its electrochemical performance due to the reduced resistance of charge transfer, and the LiMn 1− x V x PO 4 /C at x =0.025 exhibits the best rate performance.