In situ-formed LiVOPO4@V2O5 core-shell nanospheres as a cathode material for lithium-ion cells

beta-LiVOPO4 is a promising alternative cathode material for lithium-ion batteries because of its high energy density, thermal stability, and low cost, but has been suffering from poor rate and cycle performance, and not much progress has been reported. Here we report in situ-formed LiVOPO4@V2O5 core-shell nanospheres as a cathode material for lithium-ion batteries. The LiVOPO4@V2O5 core-shell nanospheres with typical sizes of 50-100 nm are successfully synthesized by a hydrothermal route followed by a surface oxidation treatment. The LiVOPO4@V2O5 nanospheres obtained are composed of an orthorhombic LiVOPO4 core with an in situ formed V2O5 shell, which are characterized by Powder X-ray diffraction(XRD), X-ray photoelectron spectrometer(XPS), Tecnai G12 transmission electron microscope(TEM) and electron energy loss spectroscopy (EELS) analyses. Electrochemical tests show that in situ-formed LiVOPO4@V2O5 core-shell nanospheres have remarkably high rate capability and long cycle life. They also deliver an initial discharge capacity of 152.8 mAh g(-1) at 0.1C while still retaining a capacity of above 100 mAh g(-1) at 0.1C after 200 cycles and possess a favorable capacity at rates of 0.5C, 1C, and 3C, perhaps the best performance demonstrated so far for LiVOPO4 cathode material, indicating its promise for application as a cathode material in advanced lithium-ion batteries.