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 abiotemplate-assisted sol–gel reaction process using low-cost beer waste brewing yeasts (BWBYs) as bothstructural template and biocarbon source. The structure and electrochemical performances of MBC-LVPwere investigated using Raman spectra, thermogravimetric measurements (TGA), adsorption–desorptionisotherms 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 at750^◦C has a hierarchical nanostructure, which consist of Li₃V₂(PO₄)₃crystal nanoparticles and amor-phous biocarbons network (11.5%) with hierarchical mesoporous structures (slit shape mesopores, openwormlike mesopores and plugged mesopores). This hierarchical nanostructure facilitates electron andlithium ion diffusion. The MBC-LVP electrode has high discharge capacity (about 205 mAh g⁻¹) at a cur-rent density of 0.2 C in the voltage region of 3.0–4.8 V and the diffusion coefficient of Li⁺-ions determinedby 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 andthe ionic and electronic transport properties.