Synthesis And Electrochemical Performance Of Li₃VO₄ Anode Materials For Lithium Ion Batteries

With the dramatically increase of human socity to the requirements of energy storage devices and the corresponding materials, the area of the investigations in new energy storage materials become the booming area, especially in the investigations of lithium battery materials. Presently, movable electronic devices, such as the digital products, notebook computer, and electronic vehicles use batteries as the power sources. The batteries in applications include lead-acid battery, nickel-hydrogen battery, Gd-Ni battery. However, these batteries have drawbacks, such as low specific energy density, bad cycling life time, and enviromental pollution, which limit the applications of these batteries. Since lithium ion batteries have priorities of higher energy density, longer cycling life-time, and even more environmentally friendly than other type batteries, the investigations to develop technologies to produce lithium batteries with even higher energy density, even longer cycling life-time, even higher charge-discharge rate become hot spots.Li₃VO₄ is a new anode material for lithium ion battery applications. Since the high theoretical specific capacity of Li₃VO₄, the investigation of Li₃VO₄ become a new area of anode material study. The application of Li₃VO₄ could possibly raise the energy density of lithium batteries.Based on the investigations of published work, we investigated the simple combinations of Li₃VO₄ with commercial microcarbon spheres?N7? or vanadium carbide ?VC? as anode materials of lithium ion batteries. The synthesis methods are simple and low costing. The investigation shows that the Li₃VO₄/N7 material has higher specific energy and longer cycling life time than it's precursors Li₃VO₄ and N7. The materials were characterized by XRD, SEM, and Laser Raman shift. The constant current charge-discharge test, cyclic voltammetry, and AC impedance test were used to characterize the electrochemical properties of the material at different experimental conditions.A Li₃VO₄/N7 material with the best electrochemical properties were obtained by simply ball milling the microspheric carbon N7 in Li₃VO₄ solution with a Li₃VO₄ loading of 20wt%?with LiOH excess of 5.0% relative to Li₃VO₄?, spraying dry, and calcining in N2 at 460?. A first discharging capacity of 491 mAh/g with a first charging capacity of 348 mAh/g was obtained at a charge-discharge rate of 100mA/g over 20wt%Li₃VO₄/N7. The charge-discharge efficience in the first cycle is 76%. After 50 cycles of charge-discharge, a specific capacity of 370 mAh/g was retained.The investigations in the combinations of Li₃VO₄ with vanadium carbide ?LiaVO4/VC? indicate that this material has reasonable specific capacity as anode material of lithium ion batteries. The VC material was prepared by calcining vanadium poly acroric acide salt. The VC material prepared with a poly acrylic acid to V2O5 ratio ?weight? of 0.7919 and calcined at 1000? performed well. The material of 35wt%Li₃VO₄/VC prepared at 500? for 6h performed the best. When tested at a current density of 100 mA/g, a first discharge capacity of 328 mAh/g with a first charge capacity of 155 mAh/g was obtained with a charge-discharge efficiency of 47%.