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Abstract: This work introduces a novel solution system not slurry to synthesize nano-micron sized Li4Ti5O12 by spray drying followed by solid-state calcination at several temperatures between 650 and 800°C. Well-crystallized Li4Ti5O12 with no impurity can be obtained at temperatures of 650, 700, 750 and 800 °C owing to the effect of nanoscale and uniform precursor powders. However, the spherical shape of the precursor powders is maintained after post-treatment at temperatures of 650 and 700°C. Because of the rough and porous nano-micron sized spherical particles, the Li4Ti5O12 obtained at relatively low calcined temperatures of 650 and 700°C show better rate capabilities than them of the Li4Ti5O12 obtained at higher temperatures of 750 and 800°C. At the relatively low calcined temperature of 650°C, the Li4Ti5O12 shows the best electrochemical performance. The initial discharge capacities are 174.8, 170.5, 167.5, 165.3, 158.2, 152.1, 130.9 and 111.9mAhg−1 at the 0.1C, 0.5C, 1C, 2C, 5C, 10C, 15C and 20C rates, respectively. After 100 cycles, the as-prepared Li4Ti5O12 retains 99.6%, 96.9%, 98.8%, 89.3%, 90.4% and 89.0% of its initial discharge capacities at the 1C, 2C, 5C, 10C, 15C and 20C rates, respectively. [Copyright &y& Elsevier]

Abstract: High energy density Li4Ti5O12 powders comprising of spherical nanocrystalline are synthesized by spray drying followed by solid-state calcination. The influences of Li/Ti atomic ratios (0.784, 0.800, 0.816, and 0.832) on the performance of Li4Ti5O12 are investigated by means of Thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscope (TEM), Galvanostatic cell cycling, as well as Ac impedance spectroscopy. The results indicate that, when the spray-drying precursors at the Li/Ti molar ratio of 0.816 are calcined at 700°C for 16h in air, a pure LTO phase with a lithium-excess composition is obtained, which shows the best properties. Between 1.0 and 2.5V (vs. Li/Li+), the initial discharge capacities of the powder are 174, 168, 163, 153, and 136 mAhg−1 at a constant current density of 0.1, 0.5, 1, 2, and 5 C, respectively. After 100 cycles, the discharge capacities of the LTO powders remain 97, 95, and 99% of initial discharge capacities at current densities of 1, 2, and 5 C, respectively. [Copyright &y& Elsevier]