Bio-assisted synthesis of mesoporous Li3V2(PO4)3 for high performance lithium-ion batteries

The mesoporous biocarbon coated Li3V2(PO4)(3) (MBC-LVP) cathode material is synthesized by a biotemplate-assisted sol-gel reaction process using low-cost beer waste brewing yeasts (BWBYs) as both structural template and biocarbon source. The structure and electrochemical performances of MBC-LVP were investigated using Raman spectra, thermogravimetric measurements (TGA), adsorption-desorption isotherms and pore-size-distribution curves, X-ray diffraction (XRD), transmission electron microscope (TEM and HRTEM), and electrochemical methods. The results show that the MBC-LVP synthesized at 750 degrees C has a hierarchical nanostructure, which consist of Li3V2(PO4)(3) crystal nanoparticles and amorphous biocarbons network (11.5%) with hierarchical mesoporous structures (slit shape mesopores, open wormlike mesopores and plugged mesopores). This hierarchical nanostructure facilitates electron and lithium ion diffusion. The MBC-LVP electrode has high discharge capacity (about 205 mAh g(-1)) at a current density of 0.2 C in the voltage region of 3.0-4.8 V and the diffusion coefficient of Li+-ions determined by CV and EIS is higher than those of olivine LiFePO4. We have revealed the formation mechanism of MBC-LVP, the possible lithium pathways in the MBC-LVP and established a relation between the structure and the ionic and electronic transport properties. (C) 2013 Elsevier Ltd. All rights reserved.