Simulated synthesis and structure of LixTiO2 nanosheets as anode material for lithium ion batteries (original) (raw)
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Lithium Coordination Sites in LixTiO2(B): A Structural and Computational Study
Chemistry of Materials, 2010
A combination of powder neutron diffraction and computational methods, based on density functional theory (DFT), have been applied to study the evolution of structure with Li content for Li x TiO 2 (B) in bulk and nanowire form. Li x TiO 2 (B) is a promising anode material for rechargeable lithium batteries. Three structures were identified, Li 0.25 TiO 2 (B), Li 0.5 TiO 2 (B), and Li x TiO 2 (B), where x corresponds to the maximum Li content, 0.8 (bulk) and 0.9 (nanowires). Together the techniques demonstrate that at low lithium concentration (up to 0.25) the square planar lithium site at the center of the b axis channel (C site) is preferentially occupied. At higher concentration, (Li 0.5 TiO 2 (B)) the C site becomes unfavorable and the 5-coordinate A1 site is occupied, whereas at the highest Li content, both A1 and a further 5-coordinate site, A2, are occupied equally.
Journal of Power Sources, 2010
Molten salt Basic environment Li4Ti5O12-TiO2 anode Lithium-ion batteries a b s t r a c t A nanocrystalline Li 4 Ti 5 O 12 -TiO 2 duplex phase has been synthesized by a simple basic molten salt process (BMSP) using an eutectic mixture of LiNO 3 -LiOH-Li 2 O 2 at 400-500 • C. The microstructure and morphology of the Li 4 Ti 5 O 12 -TiO 2 product are characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The sample prepared by heat-treating at 300 • C for 3 h (S-1) reveals dense agglomerates of ultra-fine nanocrystalline Li 4 Ti 5 O 12 ; with heat treatment at 400 • C for 3 h (S-2), there is a duplex crystallite size (fine < 10 nm, and coarse > 20 nm) of Li 4 Ti 5 O 12 -TiO 2 ; at 500 • C for 3 h (S-3), a much coarser and less-dense distribution of lithium titanate (crystallite size ∼15-30 nm) is observed. According to the results of electrochemical testing, the S-2 sample shows initial discharge capacities of 193 mAh g −1 at 0.2 C, 168 mAh g −1 at 0.5 C, 146 mAh g −1 at 1 C, 135 mAh g −1 at 2 C, and 117 mAh g −1 at 5 C. After 100 cycles, the discharge capacity is 138 mAh g −1 at 1 C with a capacity retention of 95%. The S-2 sample yields the best electrochemical performance in terms of charge-discharge capacity and rate capability compared with other samples. Its superior electrochemical performance can be mainly attributed to the duplex crystallite structure, composed of fine (<10 nm) and coarse (>20) nm nanoparticles, where lithium ions can be stored within the grain boundary interfaces between the spinel Li 4 Ti 5 O 12 and the anatase TiO 2 .
Critical Role of the Crystallite Size in Nanostructured Li4Ti5O12 Anodes for Lithium-Ion Batteries
ACS Applied Materials & Interfaces, 2018
Lithium titanate Li 4 Ti 5 O 12 (LTO) is regarded as a promising alternative to carbon-based anodes in lithium-ion batteries. Despite its stable structural framework, LTO exhibits disadvantages such as the sluggish lithium-ion diffusion and poor electronic conductivity. In order to modify the performance of LTO as an anode material, nanosizing constitutes a promising approach, and the impact is studied here by systematical experimental approach. Phase-pure polycrystalline LTO nanoparticles (NPs) with high crystallinity and crystallite sizes ranging from 4 to 12 nm are prepared by an optimized solvothermal protocol and characterized by several state-of-the-art technologies including HRTEM, XRD, PDF (pair distribution function) analysis, Raman spectroscopy and XPS. Through a wide array of electrochemical analyses, including charge/discharge profiles, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), a crystallite size of approx. 7 nm is identified as optimum particle size. Such NPs exhibit as good reversible capacity as the ones with larger crystallite sizes, but a more pronounced interfacial charge storage. By decreasing the crystallite size to about 4 nm the interfacial charge storage increases remarkably, however resulting in a loss of reversible capacity. An in-depth structural characterization using the PDF obtained from synchrotron XRD data indicates an enrichment in Ti for NPs with the small crystallite sizes, and this Ti-rich structure enables a higher Li storage. The electrochemical characterization confirms this result and furthermore points to a plausible reason why a higher Li-storage in very small nanoparticles (4 nm) results in a loss in the reversible capacity.
Growth of Lithium Lanthanum Titanate Nanosheets and Their Application in Lithium-Ion Batteries
ACS applied materials & interfaces, 2016
In this work, lithium-doped lanthanum titanate (LLTO) nanosheets have been prepared by a facile hydrothermal approach. It is found that with the incorporation of lithium ions, the morphology of the product transfers from rectangular nanosheets to irregular nanosheets along with a transition from La2Ti2O7 to Li0.5La0.5TiO3. The as-prepared LLTO nanosheets are used to enhance electrochemical performance of the LiCo1/3Ni1/3Mn1/3O2 (CNM) electrode by forming a higher lithium-ion conductive network. The LiCo1/3Ni1/3Mn1/3O2-Li0.5La0.5TiO3 (CNM-LLTO) electrode shows better a lithium diffusion coefficient of 1.5 × 10(-15) cm(2) s(-1), resulting from higher lithium-ion conductivity of LLTO and shorter lithium diffusion path, compared with the lithium diffusion coefficient of CNM electrode (5.44 × 10(-16) cm(2) s(-1)). Superior reversibility and stability are also found in the CNM-LLTO electrode, which retains a capacity at 198 mAh/g after 100 cycles at a rate of 0.1 C. Therefore, it can be c...
Ionics, 2020
The emerging portable device and electrical vehicle require safe, portable, and high-power energy sources which may be supplied by lithium-ion battery (LIB). The existing carbon anode exhibits several issues in terms of safety such as volume expansion and formation of solid electrolyte interphase (SEI) which can be overcome by applying Li 4 Ti 5 O 12 (LTO) as an anode. However, the low electronic and ionic conductivity are the main bottlenecks of LTO. This research focuses on synthesizing LTO using TiO 2 synthesized through the sol-gel method. Furthermore, the effect of TiO 2 crystalline size will be discussed accordingly. The crystalline size of TiO 2 was tailored by applying calcination temperature at 300°C, 400°C, and 500°C and was heated for 6 h. The crystallite size shown by XRD patterns was 8.01 nm, 13.82 nm, and 27.01 nm, respectively. The best electrochemical properties were exhibited by LTO 300 showing the initial specific capacity of 164 mAh g −1 .
Lithium migration at low concentration in TiO 2 polymorphs
Computational and Theoretical Chemistry, 2015
We report an atomistic simulation study at low concentration of lithium in scanning all the possible pathways for Li migration in TiO 2 polymorphs. We are particularly interested in showing the effects of the structural properties on the intercalation energies and on the energy barriers for ion diffusion. The most favourable directions for Li + transport are highlighted and we observe an anisotropic diffusion in rutile, brookite and TiO 2-B whereas the diffusion is isotropic in the case of anatase. The lowest energy barrier is calculated in rutile but it is not a key factor to determine the efficiency of Li-battery materials. Intercalation energies of stable and transition states are however important data to take into account as well as the Li pathway in order to evaluate the potentiality of each polymorph for Li migration.
TiO2 Based Nanomaterials and Their Application as Anode for Rechargeable Lithium-Ion Batteries
Titanium Dioxide - Advances and Applications, 2022
Titanium dioxide- (TiO2-) based nanomaterials have been widely adopted as active materials for photocatalysis, sensors, solar cells, and for energy storage and conversion devices, especially rechargeable lithium-ion batteries (LIBs), due to their excellent structural and cycling stability, high discharge voltage plateau (more than 1.7 V versus Li+/Li), high safety, environmental friendliness, and low cost. However, due to their relatively low theoretical capacity and electrical conductivity, their use in practical applications, i.e. anode materials for LIBs, is limited. Several strategies have been developed to improve the conductivity, the capacity, the cycling stability, and the rate capability of TiO2-based materials such as designing different nanostructures (1D, 2D, and 3D), Coating or combining TiO2 with carbonaceous materials, and selective doping with mono and heteroatoms. This chapter is devoted to the development of a simple and cost-efficient strategies for the preparatio...
Journal of Applied Electrochemistry, 2011
Li 1?x V 1-x O 2 (0 B x B 0.1) compounds were studied as the anode materials for a lithium-ion battery. The crystal and electronic structures of the prepared materials were correlated with electrical conductivities and electrochemical properties. The electrochemical behaviors were significantly dependent on the composition of Li 1?x V 1-x O 2 , and these were resulted from the perturbation of the local electronic structure arising from the increase in lithium contents in Li 1?x V 1-x O 2 rather than from the slight distortion in the crystal structure. The electrical conductivities of Li 1?x V 1-x O 2 increased with the increase in lithium contents in the compounds. Li 1.1 V 0.9 O 2 and Li 1.075 V 0.925 O 2 samples exhibit the first discharge capacities of 250 and 241 mAh g -1 at 0.2 C-rate, respectively.
The Influence of TiO2 Nanoparticles Morphologies on the Performance of Lithium-Ion Batteries
Nanomaterials
Anode materials based on the TiO2 nanoparticles of different morphologies were prepared using the hydrothermal method and characterized by various techniques, such as X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and N2 absorption. The TiO2 nanoparticles prepared were used as anode materials for lithium-ion batteries (LIBs), and their electrochemical properties were tested using discharging/charging measurements. The results showed that the initial morphology of the nanoparticles plays a minor role in battery performance after the first few cycles and that better capacity was achieved for TiO2 nanobelt morphology. The sharp drop in the specific capacity of LIB during their first cycles is examined by considering changes in the morphology of TiO2 particles and their porosity properties in terms of size and connectivity. The performance of TiO2 anode materials has also been assessed by considering their phase.
Nanocomposite particles of amorphous carbon-Li4Ti5O12 (C-LTO) and carbon nanotube-Li4Ti5O12 (CNT-LTO) were synthesized by solvothermal method and subsequent high-temperature calcination. X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and selected area electron diffraction (SAED) were applied to characterize the phase structure, particle morphology, and the coating structure. XRD analysis, TEM micrographs, HR-TEM images and SAED analysis revealed that both LTO particles exhibited a welldeveloped spinel nanocrystal structure with average sizes between 20-70 nm. The C-LTO particles exhibited roughly spherical shape coated by an amorphous carbon layer up to 10 nm in thickness. The CNT-LTO samples showed uniform square nanocrystals with edge length around 20 nm and nanoscale graphitic layers covering the surface, revealing the carbon nanotubes interconnection networks among the particle assemblies. Electrochemical studies of lithium insertion/extraction performance are evaluated by the galvanostatic charge/discharge tests, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Both LTO particles showed the superior initial discharge capacity of more than 200 mAh/g at 1/10C rate. The irreversible capacity of the C-LTO particles at more cycles was due to large polarization resulted from excessive carbon and possible residual precursors. The CNT-LTO particles show larger reversible capacity and enhanced electrochemical Li+ insertion/extraction kinetics at different cycling rates. The comparative structural and electrochemical analyses demonstrated that both nanoscale graphitic covering layers and the CNT interconnection networks increase the electronic conductivity and improve the kinetics rates of lithium insertion/extraction in the CNT-LTO particles.