V5+ Doped Li2MnSiO4/C Nanocomposite with Better Electrochemical Properties for Lithium Ion Batteries

V5+ doped Li2MnSiO4/C nanocomposites have been synthesized by a citric acid-assisted sol-gel method. The obtained Li2Mn1-xVxSiO4/C cathode materials show better electrochemical properties than undoped Li2MnSiO4. Especially, the nanocomposite Li2Mn0.94V0.06SiO4/C shows a discharge capacity of 259.1 mAh/g at 0.05 C. X-ray diffraction, high-resolution transmission electron microscoy and electrochemical impedance spectroscopy analyses indicate that the better electrochemical performances of Li2Mn1-xVxSiO4/C nanocomposites can be attributed to V5+ ions, doped into Li2MnSiO4/C, preventing the generation of MnO, and expanding the spacing of (012) planes of the lattice of the Li2MnSiO4 cathode material. The Li2Mn0.94V0.06SiO4/C exhibits relatively larger apparent Li+ diffusion coefficient than undoped Li2MnSiO4/C sample.