Fei-Fan Guo

Enhanced electrochemical performance of Li3V2(PO4)3 microspheres assembled with nanoparticles embedded in a carbon matrix

We report on uniform Li3V2(PO4)3 microspheres with a size distribution of 1–3 μm assembled with nanoparticles embedded in a carbon matrix. LVP particles have a size of about 50–100 nm and carbon accounts for about 6% in total mass for the one with the best electrochemical performance. An initial capacity of 121 mA h g−1 or 101 mA h g−1 was achieved when cycled at 1 C or 10 C at room temperature with an admissible capacity fading of 8% after 100 cycles. The high rate capability and cycling stability may attribute to the unique microsize, electron conductive continuous carbon matrix and stable 3D skeleton of Li3V2(PO4)3.

Li3V2(PO4)3 particles embedded in porous N-doped carbon as high-rate and long-life cathode material for Li-ion batteries

Porous N-doped carbon stabilized Li3V2(PO4)3 particles are prepared by a modified sol–gel method. Both the in situ doping of nitrogen and the formation of porous structure can be attributed to the addition of dicyandiamide in the sol–gel process. The composite material exhibits a high discharge capacity of 114.7 mA h g−1 at 1 C in the voltage range of 3–4.3 V after 600 cycles. Even at a high rate of 5 C, the discharge capacity of 90.5 mA h g−1 is achieved after 600 cycles. The superior electrochemical performance mainly benefits from the porous and nitrogen doped carbon.

Precursor-mediated synthesis of double-shelled V2O5 hollow nanospheres as cathode material for lithium-ion batteries

Hollow micro-/nanostructures have a wide range of applications in catalysis, rechargeable batteries, drug delivery, and gas sensors, as well as energy storage and conversion. Herein, we report a facile, template-free, precursor-mediated method to synthesize V2O5 nanomaterials with three different architectures: double-shelled hollow nanospheres, single-shelled hollow nanospheres and nanoparticles. These V2O5 nanostructures are obtained via a simple thermal treatment in air of a “pre-synthesized” vanadyl glycerolate precursor, and their morphologies can be easily tuned by varying the thermal treatment temperatures. Electrochemical studies show that the double-shelled V2O5 hollow nanospheres as a cathode material for lithium-ion batteries deliver an initial capacity of 256.7 mA h g−1 with a Coulombic efficiency of nearly 100%, and their capacity is superior to the two other V2O5 nanostructures (i.e., single-shelled hollow nanospheres and nanoparticles), mainly due to their unique double-shelled hollow structure.

Impact of carbon coating thickness on the electrochemical properties of Li3V2(PO4)3/C composites

A series of Li3V2(PO4)3/C composites with different amounts of carbon are synthesized by a combustion method. The physical and electrochemical properties of the Li3V2(PO4)3/C composites are investigated by X-ray diffraction, element analysis, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and electrochemical measurements. The effects of carbon content of Li3V2(PO4)3/C composites on its electrochemical properties are conducted with cyclic voltammetry and electrochemical impedance. The experiment results clearly show that the optimal carbon content is 4.3 wt %, and more or less amount of carbon would be unfavorable to electrochemical properties of the Li3V2(PO4)3/C electrode materials. The results would provide some basis for further improvement on the Li3V2(PO4)3 electrode materials.