Research Of Biosynthesis Of Mesoporous Phosphate Material With High-performance

Mesoporous phosphate materials with high-performance, which containmesoporous Li₃V₂（PO₄）₃/carbon microspheres, Li₃V_2-2xTi_xMg_x（PO₄）₃/carbonnanomaterial, fast ion conductor Li₂O-MgO-P₂O₅-TiO₂glass-ceramic,Li_1+0.3xTi_2-2xZn_xAl_x（PO₄）₃anode material, are synthesized using Baker’s yeast cells asboth mesoporous structure templates and amorphous carbon sources.The self-assembly leads to formation of Li₃V₂（PO₄）₃/carbon microspheres withdiameters of1⁸μm. These microspheres are composed of densely aggregatednanoparticles （20⁴0nm） as well as interconnected nanopores （2¹5nm）, and hencethey are of mesoporous nature. The mesoporous Li₃V₂（PO₄）₃/carbon microsphereshave high discharge capacity （about126.7mAh g1）, only2%capacity loss of theinitial value at the50th cycle at the current density of0.2C, and high rate capacity of100.5mAh g1at5C in the region of3.0-4.3V. The apparent Li+diffusion coefficientis found to be6.76×10^-10cm2s^-1. The microspheres could be an ideal cathode-activematerial that fulfills the requirements of rechargeable lithium batteries for high powerapplications.Li₃V_2-2xTi_xMg_x（PO₄）₃/carbon nano-material which has been biosynthesized at700oC has the largest BET surface area (72.20m²g^-1). Li₃V_2-2xTi_xMg_x（PO₄）₃/carbon, ataround x=0.3, has the highest rate capacity of158.6,133.8,115.4,98.5and35.4mAhg-1at0.1C,0.5C,1C,10C and60C in the region of3.0-4.8V. The apparent Li+diffusion coefficients were found to be3.25×10^-11、7.36×10^-11、4.28×10^-10and8.18×10^-10cm²s^-1at3.65、3.72、4.15and4.64V.Fast Li+ion conducting glass-ceramics composed of Li₂O-MgO-P₂O₅-TiO₂withmarshmallow-like and ordered hierarchical mesoporous structure have beensynthesized using yeast cells as structure templates. The mechanism of formation ofthe Li₂O-MgO-P₂O₅-TiO₂is revealed by characterizing surface morphology of theyeast cell, precursor and sample. The Li₂O-MgO-P₂O₅-TiO₂exhibits outstandingthermal stability, high conductivity and wide potential window. In the Li_1+2xMg_xTi_2-x（PO4）3system, the total conductivity （t） reaches the highest value at t=4.39×10^-5Scm^-1, the activation energy passes through a minimum value at38.68kJ mol^-1（0.38eV）, at around x=0.5. The approach may open a new green method for fabricatingordered hierarchical mesoporous materials under ambient condition. Mesoporous Li_1+0.3xTi_2-2xZn_xAl_x（PO₄）₃nano-material which has beenbiosynthesized at700oC has the largest BET surface area (72.40m²g^-1).Li_1+0.3xTi_2-2xZn_xAl_x（PO₄）₃, at around x=0.3, has the best cycling performance, with thedischarge capacity of261.5mAhg-1after50th cycles, at0.2C in the region of0.0-1.6V.It also exhibits wide potential window and outstanding thermal stability.The results show that a new biomimetic method, with yeast cell as template andbiocarbon source, can be used for synthesizing mesoporous phosphate materials withmesoporous microspheres, nanostructure, or ordered hierarchical structure, which hasimportant applications in high-powered Li-ion battery, solar cell, supercapacitor andother fields.