Li4Ti5O12 TiO2 Research Articles

Mesoporous/Microporous Li4Ti5O12/rutile-TiO2 as an anode material for lithium-ion batteries synthesized by the sol-gel method

In this work, we presented a modified sol-gel method to synthesize the nanocrystalline composite composed of Li4Ti5O12 (LTO) and rutile-TiO2, and utilized it as an efficient anode material for lithium-ion battery application. The detailed structural studies revealed that the spherical shaped rutile nanoparticles of ∼10–20 nm were homogeneously distributed on the surface of LTO and therefore the mesoporous/microporous nature of the two-phase Li4Ti5O12-TiO2 (LTO-T) was exhibited. According to a series of galvanostatic charge/discharge tests, the LTO-T electrode with the mesoporous/microporous microstructure demonstrated the improved electrochemical performance, especially at a high C rate. Interestingly, the LTO-T electrode achieved an excellent specific capacity of 175 mAh g−1 and 155 mAh g−1 even after 50 charge/discharge cycles at 1C and 5C, respectively.

Towards Environment-friendly and versatile energy storage Devices: Design and preparation of mesoporous Li4Ti5O12-TiO2 nano-hybrid electrode materials

Conventional lithium ion batteries (LIBs) present issues with ion transfer capability, and the low electronic conductivity of Li4Ti5O12 (LTO) could limit usage in energy applications. Herein, we report integrated Li4Ti5O12-TiO2 (LTO-TO) nano-hybrid synthesis by a solvothermal technique followed by a calcination process, where the phase composition of TO in LTO is optimized to enhance the rate capability and cyclic stability of the as-prepared materials. The homogeneous composite of integrated LTO-TO-4 nano-hybrid accomplish the superior cyclic performance and reversibility compared to the other compositions due to the existence of optimized secondary phase of TiO2 by using the surfactant. In the interim, to signify the outstanding rate capability of as-prepared integrated LTO-TO-4 nano-hybrid is cycled at different current densities from 100 to 8000 mA g−1 and the obtained specific capacities are 468, 337, 268, 235, 211, and 183 mAh g−1, respectively. In addition, after 300 cycles at a current density of 5000 mA g−1, as-prepared integrated LTO-TO-4 nano-hybrid depicts the specific capacity of 198 mAh g−1. From the synthetic procedure with optimized conditions and systematic characterizations, the formation of integrated LTO-TO-4 nano-hybrid shows an improved electrochemical performance than the other compositions.

A comparative study of the photocatalytic and optical properties of spinel-type titanates: A report for spinel sodium titanate

The recent discovery of Na3LiTi5O12 (NTO), which possesses spinel symmetry (Fd3¯m, #227) with the 8a site occupied by Na, has enabled investigations into the effect of the 8a-site cation on the physical properties of spinel titanates. Hence, in this study, the optical and photocatalytic properties of NTO were investigated and compared with those of spinel Li4Ti5O12 (LTO) and rutile TiO2. The bandgaps were estimated theoretically using hybrid density functional theory and experimentally using the ultraviolet–visible spectroscopy, and the obtained results were similar for both methods and spinel titanates. The valence- and conduction-band components of the spinel-type titanates were similar to those of other titanium oxides, and both NTO and LTO exhibited photocatalytic activity for sacrificial H2 evolution from water. However, although they have similar band structures and optical properties, the NTO photocatalytic activity was clearly lower than that of LTO. This can be attributed to the surface roughness and ease of defect formation in the NTO system, which hindered charge separation. These results indicate that the optical properties of spinel-type titanates can be tuned by replacing the cations at the 8a sites.

Pomegranate‐like high density LTO anode material for lithium‐ion batteries

In order to improve the rate performance and reduce the cost lithium ion anode, the Li4Ti5O12@TiO2 (LTO-TO) was prepared by a facile hydrothermal reaction method with a micro-scale TiO2 as the precursor. The morphologies and microstructures of the pomegranate-like LTO-TO were examined by scanning electron microscopy and transition electron microscopy. The results demonstrate that the nano-LTO particles are located on the surface of the micro TiO2. The electrochemical properties of the LTO-TO composites were characterized by galvanostatic charge/discharge. The as-prepared composites present a high capacity of 157.3 mAh g−1 at 0.5 C. Even at a high current density of 10 C, it can still maintain a high capacity of 105.4 mAh g−1 and remains 92.8% (95 mA g−1) after 450 cycles. These results indicate that the as-prepared LTO nano/micro-sphere may be a potential anode material for lithium-ion batteries.

Solvothermal synthesis method for dual-phase Li4Ti5O12/TiO2 composites for high-stability lithium storage

As a promising anode material, lithium titanate (Li4Ti5O12) displays extremely stable cycling and high safety performance. Nevertheless, its application is hindered because of a low electron conductivity and low specific capacity. Herein, dual-phase Li4Ti5O12/TiO2 (LTO/TO) was synthesized by a straightforward solvothermal method utilizing crystallized water of lithium hydroxide to hydrolyse tetrabutyl titanate at high temperature and pressure conditions. This work demonstrated that LTO/TO composites have excellent electrochemical performance and indicated that the inherent defects of LTO can be improved by the decoration of TO. At a current density of 1.0 A g−1 (∼6 C), the discharge capacity of LTO/TO sample reached 197 mAh g−1 after 100 cycles, while LTO exhibited 180 mAh g−1. It appears that nanostructure LTO/TO composites may shorten the diffusion distance of electrons and lithium ions.

Effect of polymer binders on the electrochemical Performance of Al-doped lithium titanate electrode

The investigation of polymers as binders of Al doped Li4Ti5O12 for Li-ion battery electrode is reported. Polimer binders such as Polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), and Polytetrafluoroethylene (PTFE) were used to make electrode sheet. Al doped Lithium Titanate (Al-doped Li4Ti5O12) were used as electrode powders. Al doped Li4Ti5O12 powders were synthesized from LiOH.H2O, TiO2 and Al2O3 via solid state reaction. X-ray diffraction (XRD) was used to analysed phase and size of particle. Electrode sheets were manufactured by used active material, binders, and acetylene black in ratio 85:10:5 wt%. Electrode sheets were cut and assembled into coin cell batteries. Coin cell samples were characterized by EIS, cyclic voltammetry and charge-discharge to get electrochemical performance. XRD result reveals that there are two phases formed from final product such as Li4Ti5O12 and rutile TiO2. EIS diagram showed that sample with PTFE binder has the best conductivity with 3.10−5 S/cm. While, cyclic voltammetry and charge-discharge test showed sample with PVDF binder has the best chemical performance with good redox peaks and highest specific capacity about 110 mAh/g.

W3Nb14O44 nanowires: Ultrastable lithium storage anode materials for advanced rechargeable batteries

Lithium-ion batteries (LIBs) have been extensively explored to meet the needs of current energy applications; nevertheless, the development of high-performance anode materials is a bottleneck for LIBs advancement. Current commercial LIBs based on graphite or Li4Ti5O12 anodes unavoidably possess some problems, such as high safety risk or low energy density. In this work, W3Nb14O44 nanowires are developed via facile electrospinning as an anode material for LIBs. The W3Nb14O44 demonstrates higher capacity, better cycling stability, and better rate performance than Ti-based compounds, such as Li4Ti5O12 and TiO2. The average working voltage plateau of W3Nb14O44 nanowires is similar to those of Li4Ti5O12 (about 1.55 V) and TiO2 (about 1.6 V), which makes it a promising alternative to the Ti-based anode materials. Furthermore, W3Nb14O44 exhibits a relatively large theoretical capacity of 293.56 mA h g−1 (W6+/W5+, Nb5+/Nb4+, and Nb4+/Nb3+). In particular, when cycled at 1000 mA g−1, W3Nb14O44 nanowires can still deliver an initial reversible capacity of 130.6 mAh g−1, while the electrospun Li4Ti5O12 nanofibers and TiO2 nanofibers can only deliver an initial reversible capacity of 95 and 75 mAh g−1, respectively. Furthermore, the in-situ X-ray diffraction, ex-situ X-ray photoelectron spectroscopy, and ex-situ transmission electron microscope results reveal that W3Nb14O44 nanowires undergo a reversible electrochemical reaction. The total volume change during charge/discharge is about 5.9%. In addition, W3Nb14O44 nanowires exhibit a large Li+ diffusion coefficient of up to 8.02 × 10–13 cm2 s−1. Such prominent merits of W3Nb14O44 nanowires make them more likely to replace Ti-based anode materials for LIBs.

In-situ constructing of hierarchical Li4Ti5O12-TiO2 microspheres assembled by nanosheets for lithium-ion batteries

The hierarchical Li4Ti5O12-TiO2 (LTO-TO) microspheres assembled by nanosheets have been in-situ synthesized through a facile hydrothermal method. The hierarchical LTO-TO microspheres have an average size of about 800 nm and the nanosheets with thickness of about 10 nm. Benefiting from the special two-dimensional nanostructure with large contact surface areas with the electrolyte and significantly shortened transport lengths of lithium ions, which are critical for enhancing cycle performance and rate capability of LIBs. The prepared product exhibits excellent cycling performance which delivers a stable reversible specific capacity of 177.3 mAh g−1 at a current rate of 0.5 C after 660 cycles, and the high rates capacity is 113.7 mAh g−1 at 10 C.

Ternary‐Phase Li4Ti5O12/TiO2 Nanosheet Composite for High Rate Lithium‐Ion Batteries

AbstractA ternary‐phase Li4Ti5O12/TiO2 (LTO/TiO2) nanosheet composite is successfully synthesized by a one‐pot hydrothermal method followed by two‐step annealing ways. It exhibits high specific capacities of 170 mAh g−1, 154 mAh g−1, 138.5 mAh g−1, and 123.9 mAh g−1 at 1 C, 10 C, 30 C and 50 C, respectively. After 3000 cycles at 20 C, over 89.2 % original specific capacity retention is maintained with approximately 100 % columbic efficiency. The excellent rate performance and cycling stability are attributed to the high crystallinity, the thin nanosheets, the high surface area, and an appropriate amount of nanostructured TiO2 seeds dispersed in the Li4Ti5O12 (LTO) matrix for the final products.

Combined Modification of Dual-Phase Li4Ti5O12-TiO2 by Lithium Zirconates to Optimize Rate Capabilities and Cyclability.

The low electrical conductivity and ordinary lithium-ion transfer capability of Li4Ti5O12 restrict its application to some degree. In this work, dual-phase Li4Ti5O12-TiO2 (LTOT) was modified by composite zirconates of Li2ZrO3, Li6Zr2O7 (LZO) to boost the rate capabilities and cyclability. When the homogeneous mixture of LiNO3, Zr(NO3)4·5H2O and LTOT was roasted at 700 °C for 5 h, the obtained composite achieved a superior reversible capacity of 183.2 mAh g-1 to the pure Li4Ti5O12 after cycling at 100 mA g-1 for 100 times due to the existence of a scrap of TiO2. Meanwhile, when the composite was cycled by consecutively doubling the current density between 100 and 1600 mA g-1, the corresponding reversible capacities are 183.2, 179.1, 176.5, 173.3, and 169.3 mAh g-1, signifying the prominent rate capabilities. Even undergoing 1400 charge/discharge cycles at 500 mA g-1, a reversible capacity of 144.7 mAh g-1 was still attained, denoting splendid cyclability. From a series of comparative experiments and systematic characterizations, the formation of LZO meliorated both the Li+ migration kinetics and electrical conductivity on account of the concomitant superficial Zr4+ doping, responsible for the comprehensive elevation of the electrochemical performance.

Interface-engineered Li4Ti5O12–TiO2 dual-phase nanoparticles and CNT additive for supercapacitor-like high-power Li-ion battery applications

The single-pot synthesis of dual-phase spinel-Li4Ti5O12 and anatase-TiO2 (LTO–TiO2) nanoparticles over all the phase fractions ranging from pure LTO to pure TiO2 is conducted. Carrying out the process over the complete range enabled the identification of a unique weight ratio of 85:15 (LTO:TiO2), providing the best combination of capacity, rate capability and cycling stability. We show that for this composition dual-phase nanoparticles have a predominant interfacial orientation of (111)LTO∣∣(004)TiO2, while it is (111)LTO∣∣(101)TiO2 for other compositions. This study therefore shows that the dual-phase interface with these specific orientations gives the best performance. The synergistic combination of dual-phase nanoparticles with multi-wall carbon nanotubes improves the performance further. This results in an electrode with supercapacitor-like rate capability delivering high discharge capacities of 174, 127, 119, 110, 101 and 91 mAh g−1 at specific currents of 2000, 6000, 12 000, 18 000, 24 000 and 30 000 mA g−1, respectively. A discharge capacity of 174 mAh g−1 at a specific current of 2000 mA g−1 with only 0.005% capacity loss per cycle over 3000 cycles is demonstrated. At current densities of 6000, 12 000 and 24 000 mA g−1, stable cycling is obtained for 1500 cycles. The present work enables nano-engineered interfaces in LTO–TiO2 dual-phase nanoparticles with an electrochemical performance that is better than its individual components, opening up the potential for high-power Li-ion battery applications.

Hierarchical porous Li4Ti5O12–TiO2 composite anode materials with pseudocapacitive effect for high-rate and low-temperature applications

Dual-phase hierarchical porous Li4Ti5O12–TiO2 (HP LTO–TO) microspheres were synthesized using a topochemical conversion method and used as an anode material in high power lithium ion batteries, particularly for use in low temperature applications.

Mechanisms of the decrease in low-temperature electrochemical performance of Li4Ti5O12-based anode materials

The electrochemical performances of Li4Ti5O12 (LTO) and Li4Ti5O12-rutile TiO2 (LTO–RTO) composite electrodes at low temperatures were evaluated. The electrochemical performance of both electrodes decreased at low temperatures; regardless, the LTO–RTO electrode performed better than the LTO electrode. First, high viscosity and low ion conductivity of liquid electrolytes at low temperatures significantly reduce electrochemical performance. Second, cycling at low temperatures changes the crystal structure of LTO–based electrodes, impeding lithium ion diffusion and even causing the diffusion path to change from easy to difficult. However, changes in the crystal structure of the LTO–RTO electrode were not sufficient to change this path; thus, diffusion continued along the 8a-16c-8a pathway. Finally, from the perspective of dynamics, aggravation of a side reaction, increase in charge transfer resistance and polarization, and decrease in lithium ion diffusion at low temperatures reduce the electrochemical performance of LTO–based anode materials. However, the activation energy based on lithium ion diffusion is lower in the LTO–RTO electrode than the LTO electrode. The results confirmed that the electrochemical performance of the LTO–RTO electrode was better than that of the LTO electrode at low temperatures.

Carbon-coated Li4Ti5O12–TiO2 microspheres as anode materials for lithium ion batteries

ABSTRACTWhile spinel Li4Ti5O12 has attracted great attention owing to its excellent cycling stability and safety as anode materials of lithium ion batteries, there is still a challenge to produce high-performance Li4Ti5O12 with a cost-effective and scalable process. Herein, we developed a facile one-pot strategy for scalable synthesis of carbon-coated Li4Ti5O12–TiO2 microspheres. The novel material not only delivered a high capacity of 162.5 mA h g−1 after 100 cycles at 0.5 C but also exhibited excellent rate capability and cycling stability. The capacity of up to 146.6 mA h g−1 was retained after 350 cycles at 5 C, and no obvious capacity reduction was found during cycles. The superior electrochemical performance can be attributed primarily to the uniform carbon layer outside and the high density of grain boundary in the compact microspheres, resulting in enhanced electrical conductivity and more channels for lithium ion insertion/extraction reaction.

Nitrogen-doped carbon-coated hierarchical Li4Ti5O12-TiO2 hybrid microspheres as excellent high rate anode of Li-ion battery

Abstract Nitrogen-doped carbon-coated Li4Ti5O12-TiO2 (LTO-TO) hybrid microspheres were prepared by heat treating the dry mixture of urea and chemically lithiated dandelion-like TiO2 microspheres in a stainless steel autoclave at 550 °C for 5 h. The hybrid materials were tested as anode of Li-ion batteries. As compared to the pristine sample, the N-doped carbon-coated LTO-TO microspheres exhibited higher specific capacity at both low and high current rates. Discharge capacities of 184 and 123 mAh g−1 were obtained at 0.2 C and 20 C, respectively. Moreover, the LTO-TO/C electrode showed excellent cycle performance, with a discharge capacity of 121.3 mAh g−1 remained after 300 cycles at 5 C, corresponding to an average capacity degradation rate of 0.073% per cycle. These high specific capacity, excellent rate capability and cycle performance demonstrated the high potentiality of the N-doped carbon-coated LTO-TO microspheres as anode material of both energy storage-type and power-type Li-ion batteries.

A Strategy for Synthesis of Nanosheets Consisting of Alternating Spinel Li4Ti5O12 and Rutile TiO2 Lamellas for High-Rate Anodes of Lithium-Ion Batteries.

Ultrathin dual phase nanosheets consisting of alternating spinel Li4Ti5O12 (LTO) and rutile TiO2 (RT) lamellas are synthesized through a facile and scalable hydrothermal method, and the formation mechanism is explored. The thickness of constituent lamellas can be controlled exactly by adjusting the mole ratio of Li:Ti in the original reactants. Alternating insertion of the RT lamellas significantly improves the electrochemical performance of LTO nanosheets, especially at high charge/discharge rates. As anodes in lithium-ion batteries (LIBs), the dual phase nanosheet electrode with the optimized phase ratio can deliver stable discharge capacities of 178.5, 154.9, 148.4, 142.3, 138.2, and 131.4 mA h g-1 at current densities of 1, 10, 20, 30, 40, and 50 C, respectively. Meanwhile, they inherit the excellent cyclic stability of pure spinel LTO and exhibit a capacity retention of 93.1% even after 500 cycles at 50 C. Our results indicate that the alternating nanoscaled lamella structure is a good alternative to facilitate the transfer of both the Li ions and electrons into the spinel LTO, giving rise to an excellent cyclability and fast rate performance. Therefore, the newly prepared carbon-free LTO-RT nanosheets with high safety provide a new opportunity to develop high-power anodes for LIBs.

Composite with TiO2 and extension of discharge voltage range for capacity enhancement of a Li4Ti5O12 battery

Herein, nanosheet-assembled Li4Ti5O12–TiO2 (LTO–TiO2) microspheres were successfully obtained via a hydrothermal method.

Hierarchical Li4Ti5O12-TiO2 microspheres assembled from nanoflakes with exposed Li4Ti5O12 (011) and anatase TiO2 (001) facets for high-performance lithium-ion batteries

Hierarchical Li4Ti5O12-TiO2 microspheres are synthesized via an oil/water interface method with the assistance of cetyltrimethylammonium bromide (CTAB) and following calcination. The as-prepared Li4Ti5O12-TiO2 microspheres are consisted of nanoflakes (ca. 15nm in thickness); moreover, Li4Ti5O12 and anatase TiO2 in the nanoflake building blocks are bounded by (011) and (001) facets, respectively. More especially, it is found that CTAB plays a very important role in the phase and morphology of the Li4Ti5O12-TiO2 composite. When employed as the anode materials for lithium-ion batteries, the Li4Ti5O12-TiO2 microspheres show initial discharge capacities of 234, 170, 151 and 140mAhg−1 at charge/discharge rate of 1, 5, 10, and 20C, respectively; furthermore, after 100 cycles at 5C, the discharge capacity remains at 158mAhg−1 with a capacity retention of 92.9%. The excellent electrochemical properties of the product can be ascribed to the synergistic effect of the exposed Li4Ti5O12 (011) and anatase TiO2 (001) facets, abundant phase interfaces, hierarchical structures, and thin flake-like building blocks.

Lithium-Ion Capacitor Based on Electrodes Constructed Via Electrostatic Spray Deposition

Conventional Electrochemical double-layer capacitors (EDLCs) are well suited as power devices that can provide large bursts of energy in short time periods. However, their relatively poor energy densities hinder their application in devices that require a simultaneous supply of both high energy and high power. In the wake of addressing this shortcoming of EDLCs, the concept of hybridization of lithium-ion batteries (LIBs) and EDLCs has gained significant scientific interest in past few years. Such a device, generally referred to as the “lithium-ion capacitor” typically utilizes a lithium intercalating electrode along with a fast charging capacitor electrode in a lithium-containing electrolyte. Herein we have constructed a lithium ion capacitor comprising a Li4Ti5O12 –TiO2 (LTO-TiO2) anode and a graphene and carbon nanotube (G-CNT) composite cathode using electrostatic spray deposition (ESD). The morphology and material properties were studied using scanning and transmission electron microscopy and X-ray diffraction studies, respectively. Electrochemical characterization was thereafter carried out for both the half cells as well as full cells.

Binary Lithium Titanate–Titania Nanocomposite Thin‐Film Electrodes for Electrochemical Energy Storage

AbstractThis work introduces a facile approach for preparation of binary nanocomposite thin film electrodes for lithium‐ion batteries with excellent storage capability, high rate performance, and good electrochemical stability. The Li4Ti5O12‐TiO2 film electrodes are prepared by radio frequency (RF) magnetron sputtering deposition using a Li4Ti5O12 and TiO2 powder mixture target as sputtering source in an argon atmosphere. The Li4Ti5O12–TiO2 electrode yields good electrochemical performance in terms of high capacity (295 mAh g−1) at a current density of 0.1 C, good cycling stability (≈5 % capacity loss after 100 cycles at 0.1 C), and excellent rate capability (158 mAh g−1 at a current density of 5 C). The factors contributing to the excellent electrochemical performance are related to the binary nanocomposite structure. The results suggest that the Li4Ti5O12–TiO2 nanocomposite thin film can be used as an anode material for high‐performance lithium‐ion batteries.