Papers by Keyword: Lithium Titanate

Abstract: Carbon coated lithium titanate (Li₄Ti₅O₁₂/C) was obtained by a facile solid state approach in inert Ar atmosphere. The composition, morphology, residual carbon content and Ti valence of the samples were systematically investigated. The carbon content of Li₄Ti₅O₁₂/C should be optimized, since excess carbon in the composite leads to the reduction of Ti (IV) to form Ti (III), which results in large irreversible capacity of Li₄Ti₅O₁₂/C. With an optimal carbon content of 0.68wt%, the Li₄Ti₅O₁₂/C sample shows high rate capabilities and good cycling ability, delivering discharge capacities of 160.8 mAh/g at 5C. The superior high rate properties are ascribed to the specific nanostructures, which enables fast electronic and ionic transport by introducing carbon coating and decreasing the particle size of lithium titanate.

Abstract: Lithium Titanate (LTO) is one of the anode materials that has good performance because of its unique properties, which is zero-strain. In this study, LTO was synthesized using the sol-gel method and mechanochemical hydrothermal with LiOH as the source of lithium-ion. Silicone oxycarbide (SiOC) is a ceramic material synthesized through a simple pyrolysis process of silicone oil precursors. Carbon used in this study is a carbon activated process so that activated carbon is obtained with a large pore size. The addition of activated carbon to the LTO is done during the sol-gel process, while the addition of SiOC to LTO-C is performed during the slurry making process. SEM-EDS shows the extent of the elements in the sample where Ti, F, Si, O, and C are present. Also, SEM-EDS characterization shows an increase in the amount of carbon in each sample. XRD shows the presence of the LTO spinel phase and impurity phases such as TiO₂ rutile and anatase, and Li₂TiO₃. In EIS performance testing, low resistivity expresses high conductivity. In this research, high conductivity is owned by LTO-1% C/SiOC. In addition, CV and CD performance tests were performed where the highest specific capacity was obtained in the LTO-5%/SiOC samples.

Abstract: We synthesized nano-Li₄Ti5O₁₂ particles by solvothermal method. The as-prepared materials were characterized by XRD, SEM, TEM and electrochemical measurements. The Li₄Ti5O₁₂Li4Ti5O12 showed excellent rate capability and cycle ability. The as-preparedLi₄Ti5O₁₂ Li4Ti5O12 electrode exhibited highly initial discharge capacity 176 mAh/g at 0.1 C rate up to, which was slightly higher than its theoretical capacity (175 mAh/g). By increasing the C-rate, the cell showed 152, 143, 138 and 135 mAh/g at 0.5, 1, 1.5 and 2 C, respectively.

Abstract: Li₄Ti₅O₁₂ pure and Li₄Ti₅O₁₂ with Na and Al doped Li_(3-x/3)Al_xNaTi_(5-2x/3)O₁₂ (x=0, 0.025, 0.05, 0.075) as anodes for Li-ion batteries are synthesized at 850°C via solid state reaction using Li₂CO₃, TiO₂-anatase, Al₂O₃ and Na₂CO₃ as precursor. The effect of substitution of Al and Na in Li₄Ti₅O₁₂ on characterization of precursor and electrochemical performance is studied. It is found that Na doped in Li₄Ti₅O₁₂ pure affected the formation of three phase i.e NaLiTi₃O₇, Li₄Ti₅O₁₂, dan Li₂TiO₃. Meanwhile, Al doped contributed to the formation of NaLiTi₃O₇ phase significantly. The SEM images show that the particles have polyhedral shape with uniform size distribution. Na doped in the Li₄Ti₅O₁₂ affected particle size become larger against Al doped particle size become smaller than undoped material, the best particle size measured by PSA is 30,89 . All characterization of material will determine the electrochemical performance of Li-ion battery.

Abstract: Spherical Li₂Ti₃O₇ precursor powders were successfully prepared by spray pyrolysis. X-ray diffraction analysis revealed that the ramsdellite phase was obtained by calcining at 1100 °C for 3 h under an argon/hydrogen (95/5 %) atmosphere. The Li₂Ti₃O₇ anode exhibited higher rechargeable capacity and excellent cycle stability. The rechargeable capacity of the Li₂Ti₃O₇ anode was approximately 168 mAh/g at 0.1 C. The discharge capacity of the Li₂Ti₃O₇ anode after 100 cycles was approximately 90% of the initial discharge capacity.

Abstract: Li₄Ti₅O₁₂ thin film anodes were prepared successfully using pulsed laser deposition technique. The thin films were characterized by X-ray diffraction and environmental scanning electron microscopy. The effects of thickness and scan rate on the electrochemical properties of Li₄Ti₅O₁₂ thin film electrodes were discussed in detail. The thin film anodes deliver favorable capacity and excellent cycling performance. The discharge capacity maintains at 141 mAhg^-1 after 20 cycles at 1C charge-discharge rate for the thin film anodes deposited for 20 minutes. The charge-transfer resistances were also investigated by electrochemical impedance spectroscopy.

Abstract: Fabrication of lithium silicate powder containing lithium titanate by solid phase reaction method. LiFabrication of lithium silicate powder doped with lithium titanate by solid-state reaction. Take lithium carbonate, silicon dioxide and titania as raw materials and then these powders were mixed according to the different ratios and grinded in an agate mortar for 15 min. And then the mixture were dried at 80°C. Finally, the samples were sintered in vacuum tube furnace at 750, 800, 850 and 900°C for 2h. Thermogravimetric analysis, differential scanning calorimetry and XRD analysis were carried out systematically in this paper. The reaction process and mechanism at different temperatures and the effect of the different ratios and sintering temperature were discussed. Experimental results showed that lithium titanate component increased with increasing amount of titanium dioxide. While the mixture were sintered at 900°C for 2h, there would have lithium silicate and lithium titanate phase.

Abstract: Being inherently safe and chemically compatible with the electrolyte, lithium titanate is considered alternatives to carbonaceous anodes in Li-ion batteries. Given the commercial success of the spinel lithium titanate, carbon coated lithium titanate, particularly in nano structured forms, have been fabricated and investigated for the applications. Nano structuring leads to increased reaction areas, shortened Li+ diffusion and potentially enhanced solubility/capacity. This paper reviews structural characteristics and electrochemical reactivity, along with synthetic approaches of carbon coated nanostructures and nano-composites based on lithium titanate, recently.

Abstract: Spinel-type structured Li4+xTi5O12 (0 6 x 6 3 ) is actually one of the most promising anode materials for Li ion batteries. In its nanostructured form it is already used in some commercially available Li ion batteries. As was recently shown by our group (Wilkening et al., Phys. Chem. Chem. Phys. 9 (2007) 1239), Li diffusivity in microcrystalline Li4+xTi5O12 with x = 0 is rather slow. In the present contribution the Li conductivity in nanocrystalline samples of the electronic insulator Li4Ti5O12 prepared by different routes is investigated using impedance spectroscopy. The mean crystallite size of the samples is about 20 nm. The ionic conductivity of nanocrystalline Li4Ti5O12 obtained by mechanical treatment is higher by about two orders of magnitude compared to that found for a material which was prepared following a sol-gel method. The latter resembles the behaviour of the microcrystalline sample with an average particle size in the μm range rather than that of a nanocrystalline ball milled one with a mean crystallite size of about than 20 nm. The larger conductivity of the ball milled sample is ascribed to a much higher defect density generated when the particle size is reduced mechanically.

Abstract: In order to reproduce the observed ionic conductivities and activation energies computationally, the potential parameters (PMs) were optimized for classical molecular dynamic simulations on Li ion conduction in the A-site deficient perovskite solid solution La056Li0.33TiO3 with disordered A-site ion arrangement. By the use of the optimized PMs, the conductivities and the activation energies were improved considerably from 4.1×10-3 Scm-1 to 4.4×10-2 Scm-1 at 800 K and 0.02 eV to 0.2 eV, respectively. The pair correlation functions calculated with the optimized PMs reveal that the Li-ions are located somewhat broadly mainly in the vicinity of the midpoint between the center of the A-site and the center of the bottleneck formed by four O2-, and that the simulated Li location is significantly related to the conductivity.