Core-shell VPO4/C anode materials for Li ion batteries: Computational investigation and sol-gel synthesis

Pristine VPO4 is a ground-state magnetic semiconductor, disclosed by density functional theory computations; therefore, core-shell VPO4/C composites were proposed and prepared via a sol-gel route. X-ray diffraction confirms the phase of orthorhombic vanadium phosphate, and scanning electron microscopy and transmission electron microscopy show that VPO4 particles are coated with amorphous carbon film of similar to 8 nm in thickness to form core-shell nanostructures. Galvanostatic charge/discharge and cyclic voltammetry tests demonstrate that both the initial and reversible lithium storage capacities of VPO4 were apparently enhanced due to the carbon coating. Core-shell structures can effectively improve the electrochemical performances of phosphate-based Li-ion battery materials. (C) 2012 Elsevier B.V. All rights reserved.