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We demonstrate a simple and green approach for the synthesis of one kind of anatase TiO 2 nanosheets. The method is based on a hydrothermal method under normal atmosphere without using the complex Teflon-lined autoclave, high concentrations NaOH solution and long reaction time. The as-prepared materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) and electrochemical measurements. The obtained anatase TiO 2 nanosheets show excellent performance. There is one pair of potential plateaus at 1.7 and 1.9 V in the process of Li insertion and extraction, and the initial Li insertion/extraction capacities are 382 and 326 mA h g −1 at the current density of 20 mA g −1 , respectively. After 50 cycles, the TiO 2 retains 93% of the initial charge capacity at the current density of 400 mA g −1 . [ABSTRACT FROM AUTHOR]

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: We demonstrate an aqueous mixing technique to synthesize nano-micron Li4Ti5O12 by spray drying followed by solid-state calcination. The as-prepared materials are characterized by XRD, TG–DTA, SEM, TEM and electrochemical measurements. Well-crystallized Li4Ti5O12 with no impurity can be obtained at a relatively low calcined temperature (650°C) owing to the effect of nanoscale and uniform particles. Because of the rough and porous nano-micron spherical particles, the obtained Li4Ti5O12 shows excellent rate capability and cycle ability. 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 0.1, 0.5, 1, 2, 5, 10, 15 and 20 C 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 1, 2, 5, 10, 15 and 20 C rates, respectively. [Copyright &y& Elsevier]

Abstract: We demonstrate a simple, improved and novel approach for the synthesis of a kind of anatase TiO2 nanosheets and Li4Ti5O12 anode material with excellent electrochemical performance from the natural ilmenite. We use the H2O2 to leach the Ti from the hydrolyzed titania residue under alkaline condition of leaching. Before boiling, the LiOH was added into the leach solution. The obtained precipitation of titanium dioxide hydrate can be purified and refined into special nanostructure by the addition of LiOH. SEM and XRD show that the as-prepared TiO2 are special nanostructure and well-crystallized anatase phase. The analysis of elemental contents reveals that the content percent of TiO2 in as-prepared TiO2 nanosheets is more than 99%. Moreover, the titanium dioxide hydrate can be used to prepare Li4Ti5O12 anode material directly. The obtained Li4Ti5O12 shows charge specific capacities of 161,138 and 113mAhg−1 at 0.1C, 0.5C and 1C rates, respectively, and excellent cycling stability. [Copyright &y& Elsevier]

Abstract: We demonstrate a simple and novel approach for the synthesis of a kind of anatase TiO2 nanowires. The method is based on a hydrothermal method under normal atmosphere without using the complex Teflon-lined autoclave, high concentrations NaOH solution and long react time. The as-prepared materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements. The obtained anatase TiO2 nanowires show excellent performance. There is a potential plateau at 1.77 and 1.88V in the process of Li insertion and extraction, and the initial Li insertion/extraction capacities are 283 and 236mAhg−1 at the density of 20mAg−1, respectively. In the 20th cycle, the reversible capacities still remain about 216 and 159mAhg−1 at the current densities of 20 and 200mAg−1, respectively, and the coulombic efficiency is more than 98%, exhibiting excellent electrochemical performance. [Copyright &y& Elsevier]

Abstract: Spinel Li4Ti5O12 anode material is successfully synthesized by a solid-state method using lithium carbonate and titanium precursors which are prepared by the low cost industrial titanyl sulfate solution. The characters of H2TiO3 and TiO2 precursors are determined by TG/DTA and SEM methods. TG-DAT and EDS methods show that H2TiO3 can absorb sulphate ions which can be present as impurities. XRD method shows that the impure phases of Li2SO4 and rutile TiO2 appear in Li4Ti5O12 synthesized by H2TiO3. The formation of Li2SO4 is identified in thermodynamics during the process of calcination. Owing to the formation of Li2SO4 impurity, the capacity of the Li4Ti5O12 synthesized by H2TiO3 is low. One effective way that can tackle this problem is to remove the sulphur by calcining H2TiO3, after calcinations, the production will have a thermal treatment with Li2CO3. The obtained Li4Ti5O12 shows better electrochemical performance. The specific capacities can be increased by 20mAhg−1 at 0.1, 0.5 and 1C rates. [ABSTRACT FROM AUTHOR]

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]

Abstract: Using nano-Si, glucose and flake graphite of ∼0.5μm as raw materials, flake graphite/silicon/carbon composite is successfully synthesized via spray drying and subsequent pyrolysis. The samples are characterized by XRD, SEM, TEM and electrochemical measurements. The composite is composed of flake graphite, nano-Si and amorphous glucose-pyrolyzed carbon and presents good spherical appearance. Some micron pores arising from the decomposition of glucose exist on the surface of the composite particles. The composite has a high reversible capacity of 602.7mAh/g with an initial coulombic efficiency of 69.71%, and shows nearly the same cycleability as the commercial graphite in 20 cycles. Both the glucose-pyrolyzed carbon and the micron pores play important roles in improving the cycleability of the composite. The flake graphite/silicon/carbon composite electrode is a potential alternative to graphite for high energy-density lithium ion batteries. [Copyright &y& Elsevier]

Abstract: Titanium-containing precursor is prepared from the high-titanium residue, which is obtained from the ilmenite by a mechanical activation and leaching process. After two-step alkaline leaching, about 95% of silicon dioxide is separated from the high-titanium residue. The purified titanium-containing precursor is used to synthesize Li4Ti5O12. XRD shows that the synthesized Li4Ti5O12 is cubic spinel phase and well crystallized. At the discharge-charge rate of 0.1C and 0.5C, its discharge capacities are 138.3 and 126.8 mAh/g, respectively. [ABSTRACT FROM AUTHOR]