Mesoporous Li4Ti5O12 Research Articles

Construction of in situ C/N/S co-doped mesoporous Li4Ti5O12 nanosheets for high-rate and large-capacity lithium-ion batteries

The low capacity of Li4Ti5O12 (LTO) under high-rate charging/discharging limits its development in energy applications. Two-dimensional (2D) nanosheets equipped with mesopores offer promising opportunities to realize high-rate and long-term lithium-ion batteries. This paper successfully synthesized C/N/S co-doped lithium titanate nanosheets with rich oxygen vacancy concentration (CNSLTO) in a single step. C, N and S are doped into the LTO bulk phase, providing bulk oxygen vacancies and active sites. Partial Ti4+ conversion to Ti3+ is promoted by co-doping and introducing rich oxygen vacancies, improving the electrical conductivity. In addition, the effect of CTAB concentration on the morphology and electrochemical properties of the materials was studied experimentally. The optimized CNSLTO nanosheets have a relatively high specific surface area (99.38 m2 g−1) and numerous mesoporous, achieving outstanding performance and excellent cycling stability at high-rate as lithium-ion anode materials. The CNSLTO exhibits excellent rate capacity (171.7–152.6 mA h g−1 at 0.5–20 C) and cycling performance (97.6 % after 1000 cycles at 10 C). Additionally, the discharge-specific capacity of the LFP//CNSLTO full battery at 10 C (122.2 mA h g−1) was superior to the LFP//LTO (77.8 mA h g−1).

Sol-Gel Synthesis of Nanocrystalline Mesoporous Li4Ti5O12 Thin-Films as Anodes for Li-Ion Microbatteries.

The development of anodes based on Li4Ti5O12 (LTO) for lithium ion batteries has become very important in recent years on the basis that it allows a long service life (stability in charge-discharge cycling) and safety improvements. The processing of this material in the form of thin film allows for greater control of its characteristics and an improvement of its disadvantages, namely reduced electrical conductivity and low diffusion of lithium ions. In this work, we try to limit these disadvantages through the synthesis of a mesostructured carbon-doped Li4Ti5O12 thin-film with a pure spinel phase using a combination of a block-copolymer template and in situ synthesis of Li-Ti double alkoxide. Structural and electrochemical characterization has been carried out to determine the best conditions (temperature, time, atmosphere) for the thermal treatment of the material to reach a compromise between crystallinity and porosity distribution (pore size, pore volume, and interconnectivity).

Construction of mesoporous Li4Ti5O12 hollow spheres for high rate lithium ion batteries

In this study, a simple targeted etching approach was developed for the controlled fabrication of mesoporous Li4Ti5O12 (LTO) hollow spheres, which can be used as an advanced anode material in lithium-ion batteries. We investigated the controllable synthesis of mesoporous LTO hollow spheres with various hollow structures based on different compositions, such as yolk-shelled and hollow structures with porous shells. The as-prepared mesoporous LTO hollow spheres had several main structural advantages, including high intrinsic interfacial reactivity with the electrolyte due to a high specific surface area, extra space for the storage of lithium ions, and reduced transport path lengths for both e– and Li+, thereby leading to excellent rate performance. Moreover, the high reversible capacity of the mesoporous LTO hollow spheres was 229.2 mA h g−1 after 1000 cycles at 0.5C and the highest rate discharge capacity was 114.2 mA h g−1 at 10 C, thereby indicating the outstanding cycle stability and rate performance of LTO as an anode in lithium-ion batteries.

Understanding the formation of ultrathin mesoporous Li4Ti5O12 nanosheets and their application in high-rate, long-life lithium-ion anodes

Two-dimensional nanosheet-like materials with ultra-small thickness and uniform porous structures hold great promise for high-rate and long-life lithium-ion batteries. In this work, pure ultrathin mesoporous Li4Ti5O12 nanosheets are fabricated by combining a facile solvothermal synthesis with a calcination process. The detailed formation mechanism of ultrathin mesoporous Li4Ti5O12 nanosheets is systematically investigated, which identified the key factors that control the structure development. The unique structural features including ultra-small thickness, large specific surface area and uniform mesoporous structures endow such materials with effective charge transport channels, abundant reaction active sites and inner-plain void space for improved structural stability. As a result, the ultrathin mesoporous Li4Ti5O12 nanosheets offer nearly theoretical capacity (174 mA h g-1 at 1 C), very high rate capability (e.g., 145 mA h g-1 at 50 C), and excellent cycling stability (95% capacity retention after 2500 cycles at 20 C), suggesting their great promise as anode materials for ultrahigh-power and long-life lithium-ion batteries.

Synthesis of Li4Ti5O12 Microspheres and Their Electrochemical Performance As Anode Materials for Li-Ion Batteries

Lithium titanate, Li4Ti5O12 (LTO) has drawn significant attention in the lithium ion battery because it shows some interesting features such as a low toxicity and low volume change (2-3%) on both lithium insertion and de-insertion, along with an excellent cycling life. Especially, the mesoporous LTO microspheres are considered as an ideal anode material because of their good rate performance, morphological properties, and a large tap density. However, it is very challenging to synthesize monodispersed LTO microspheres with desirable structural characteristics and electrochemical performances. In this study, LTO microspheres were synthesized using a facile process and cheap Ti-source (TiOSO4). The round shaped secondary particles (μm scale) were consisted of LTO primary particles (< 100 nm). The structural properties and electrochemical performances of Li4Ti5O12 microspheres will be discussed in the Meeting.

Fast synthesis of uniform mesoporous titania submicrospheres with high tap densities for high-volumetric performance Li-ion batteries

High-tap density electrode materials are greatly desired for Li-ion batteries with high volumetric capacities to fulfill the growing demands of electric vehicles and portable smart devices. TiO2, which is one of the most attractive anode materials, is limited in their application for Li-ion batteries because of its low tap density (usually <1 g cm−3) and volumetric capacity. Herein, we report uniform mesoporous TiO2 submicrospheres with a tap density as high as 1.62 g cm−3 as a promising anode material. Even with a high mass loading of 24 mg cm−2, the TiO2 submicrospheres have impressive volumetric capacities that are more than double those of their counterparts. Moreover, they can be synthesized with ~100% yield and within a reaction time of ~6 h by optimizing the experimental conditions and formation mechanism, exhibiting potential for large-scale production for industrial applications. Other mesoporous anode materials, i.e., high-tap density mesoporous Li4Ti5O12 submicrospheres, are fabricated using the generalized method. We believe that our work provides a significant reference for the industrial production of mesoporous materials for Li-ion batteries with a high volumetric performance.

Synthesis of Mesoporous Lithium Titanate Thin Films and Monoliths as an Anode Material for High-Rate Lithium-Ion Batteries.

Mesoporous Li4 Ti5 O12 (LTO) thin film is an important anode material for lithium-ion batteries (LIBs). Mesoporous films could be prepared by self-assembly processes. A molten-salt-assisted self-assembly (MASA) process is used to prepare mesoporous thin films of LTOs. Clear solutions of CTAB, P123, LiNO3 , HNO3 , and Ti(OC4 H9 )4 in ethanol form gel-like meso-ordered films upon either spin or spray coating. In the assembly process, the CTAB/P123 molar ratio of 14 is required to accommodate enough salt species in the mesophase, in which the LiI /P123 ratio can be varied between molar ratios of 28 and 72. Calcination of the meso-ordered films produces transparent mesoporous spinel LTO films that are abbreviated as Cxx-yyy-zzz or CAxx-yyy-zzz (C=calcined, CA=calcined-annealed, xx=LiI /P123 molar ratio, and yyy=calcination and zzz=annealing temperatures in Celsius) herein. All samples were characterized by using XRD, TEM, N2 -sorption, and Raman techniques and it was found that, at all compositions, the LTO spinel phase formed with or without an anatase phase as an impurity. Electrochemical characterization of the films shows excellent performance at different current rates. The CA40-350-450 sample performs best among all samples tested, yielding an average discharge capacity of (176±1) mA h g-1 at C/2 and (139±4) mA h g-1 at 50 C and keeping 92 % of its initial discharge capacity upon 50 cycles at C/2.

Advanced Mesoporous Spinel Li4Ti5O12/rGO Composites with Increased Surface Lithium Storage Capability for High-Power Lithium-Ion Batteries.

Spinel Li4Ti5O12 (LTO) and reduced graphene oxide (rGO) are attractive anode materials for lithium-ion batteries (LIBs) because of their unique electrochemical properties. Herein, we report a facile one-step hydrothermal method in preparation of a nanocomposite anode consisting of well-dispersed mesoporous LTO particles onto rGO. An important reaction step involves glucose as a novel linker agent and reducing agent during the synthesis. It was found to prevent the aggregation of LTO particles, and to yield mesoporous structures in nanocomposites. Moreover, GO is reduced to rGO by the hydroxyl groups on glucose during the hydrothermal process. When compared to previously reported LTO/graphene electrodes, the newly prepared LTO/rGO nanocomposite has mesoporous characteristics and provides additional surface lithium storage capability, superior to traditional LTO-based materials for LIBs. These unique properties lead to markedly improved electrochemical performance. In particular, the nanocomposite anode delivers an ultrahigh reversible capacity of 193 mA h g(-1) at 0.5 C and superior rate performance capable of retaining a capacity of 168 mA h g(-1) at 30 C between 1.0 and 2.5 V. Therefore, the newly prepared mesoporous LTO/rGO nanocomposite with increased surface lithium storage capability will provide a new opportunity to develop high-power anode materials for LIBs.

Mesoporous Li4Ti5O12 nanoclusters anchored on super-aligned carbon nanotubes as high performance electrodes for lithium ion batteries.

Mesoporous lithium titanate (LTO) nanoclusters are in situ synthesized in a network of super aligned carbon nanotubes (SACNTs) via a solution-based method followed by heat treatment in air. In the LTO-CNT composite, SACNTs not only serve as the skeleton to support a binder-free electrode, but also render the composite with high conductivity, flexibility, and mechanical strength. The homogeneously dispersed LTO nanoclusters among the SACNTs allow each LTO grain to effectively access the electrolyte and the conductive network, benefiting both ion and electron transport. By the incorporation of LTO into the CNT network, mechanical reinforcement is also achieved. When serving as a negative electrode for lithium ion batteries, such a robust composite-network architecture provides the electrodes with effective charge transport and structural integrity, leading to high-performance flexible electrodes with high capacity, high rate capability, and excellent cycling stability.

Black mesoporous Li4Ti5O12−δ nanowall arrays with improved rate performance as advanced 3D anodes for microbatteries

3D black mesoporous Li4Ti5O12−δ nanowall arrays with greatly enhanced rate performance are fabricated as promising anodes for advanced lithium-ion microbatteries.

Mesoporous Li4Ti5O12 nanoparticles synthesized by a microwave-assisted hydrothermal method for high rate lithium-ion batteries

Mesoporous spinel Li4Ti5O12 nanoparticles with the diameter of around 40nm and the average pore size of about 8nm were prepared by a rapid microwave-assisted hydrothermal method followed by low-temperature calcination. Electrochemical tests reveal that the Li4Ti5O12 mesoporous nanoparticle electrode exhibits high discharge capacities of 174, 165, 157, 148, 137 and 123mAhg−1 at 1, 2, 5, 10, 20 and 40C, respectively. The electrode still delivers a capacity of 90mAhg−1 even at the highest rate of 60C (~10,000mAg−1), corresponding to a time of 60s to fully discharge/charge the materials. Moreover, the capacity of the Li4Ti5O12 mesoporous nanoparticle electrode can be completely recovered to 174mAhg−1 when the discharge rate returns to 1C after continuous 10cycles at 60C. This electrode also exhibits outstanding long-term cycling stability with only 1.8% capacity degradation for each 100cycles at 60C, and the electrode is still able to deliver the reversible charge capacities of 95mAhg−1 after 500cycles. These superior electrochemical properties result from its favorable morphology with interconnected nanoparticles and uniform mesoporous, which significantly decreases the contact resistance, shortens the lithium diffusion distances and provides more locations for lithium surface storage.

Polymer‐Templated Mesoporous Li4Ti5O12 as a High‐Rate and Long‐Life Anode Material for Rechargeable Li‐Ion Batteries

AbstractThe synthesis, characterization and Li‐storage properties of cubic mesostructured lithium titanate spinel (Li4Ti5O12) with uniform pores of diameter ≤15 nm and sub‐10 nm grains is reported. The material was prepared in powder form by sol–gel co‐assembly through a soft‐templating method using a poly(isobutylene)‐block‐poly(ethylene oxide) diblock copolymer structure‐directing agent. Electron microscopy demonstrates the mesoporous nature; the BET surface area is around 100 m2 g−1. Rietveld analysis of XRD data and results from XPS, FTIR and Raman spectroscopy indicate a large sensitivity of the phase composition to variations in the heating rate and temperature. Mesoporous Li4Ti5O12 obtained after heating to 600 °C at 10 °C min−1 is virtually single phase, with minor traces of Li2CO3 accumulated on the surface. Half‐cells with a Li metal anode display superior cycling (5 % capacity decay between the fifth and 300th cycles at C/2) and rate performance (&gt;100 mA h g at 10C).

Unique mesoporous spinel Li4Ti5O12 nanosheets as anode materials for lithium-ion batteries

Spinel Li4Ti5O12 (LTO) has been intensively investigated as promising anode materials for lithium-ion batteries (LIBs) due to its remarkable structural stability and excellent safety. In this paper, unique LTO nanosheets with porous microstructure are successfully prepared for the first time by a facile approach without any additives and template under hydrothermal conditions following calcination. Particularly, compared with traditional LTO microspheres and smooth LTO nanosheets, the newly prepared mesoporous LTO nanosheets demonstrate extra surface lithium storage reaction and much improved electrochemical performances, delivering ultrahigh reversible capacity of 169 mAh g−1 at 1C and superior rate performance of more than 140 mAh g−1 at 30C between 1.0 and 2.5 V vs. Li+/Li. The beneficial surface lithium storage is mainly attributed to its advanced microstructure, which can facilitate the transfer of lithium-ions and electrons. The exceptionally improved electrochemical performance of the mesoporous LTO nanosheets will undoubtedly make this microstructure attractive for high performance electrode materials of LIBs.

Mesoporous spherical Li₄Ti₅O₁₂ as high-performance anodes for lithium-ion batteries.

Porous microspherical Li4Ti5O12 aggregates (LTO-PSA) can be successfully prepared by using porous spherical TiO2 as a titanium source and lithium acetate as a lithium source followed by calcinations. The synthesized LTO-PSA possess outstanding morphology, with nanosized, porous, and spherical distributions, that allow good electrochemical performances, including high reversible capacity, good cycling stability, and impressive rate capacity, to be achieved. The specific capacity of the LTO-PSA at 30 C is as high as 141 mA h g(-1), whereas that of normal Li4Ti5O12 powders prepared by a sol-gel method can only achieve 100 mA h g(-1). This improved rate performance can be ascribed to small Li4Ti5O12 nanocrystallites, a three-dimensional mesoporous structure, and enhanced ionic conductivity.

Mesoporous Li4Ti5O(12-x)/C submicrospheres with comprehensively improved electrochemical performances for high-power lithium-ion batteries.

To comprehensively improve the performance of Li4Ti5O12 (LTO), a synergistic method combining compositing, crystal structure modification and hierarchical particle structuring is employed in this work. Monodispersed/multidispersed mesoporous Li4Ti5O12-x/C submicrospheres were fabricated using monodispersed/multidispersed TiO2 submicrospheres, lithium hydroxide and sucrose as precursors. The Li4Ti5O12-x/C submicrospheres have a well-crystallized spinel structure, no blockages of Li(+) ion transport pathways, 2.69-3.03% O(2-) vacancy contents (vs. all 32e sites in the spinel structure), and 12.9-14.6% Ti(3+) ion contents (vs. all titanium ions). Thus, the electronic conductivity and Li(+) ion diffusion coefficient of particles can be significantly improved, and the working potential is 4.4-4.7 mV lower than that of LTO. Furthermore, these submicrospheres contain 1.06-1.44 wt% carbon as carbon coatings (2-3 nm in thickness) and carbon nanoparticles (∼20 nm in size), resulting in smaller primary particle sizes (<100 nm), large specific surface areas (12-15 m(2) g(-1)), proper pore sizes (∼4 nm) and enhanced electrical conduction between particles. In addition, the submicrospherical morphology allows large tap densities (1.41-1.71 g cm(-3)). As a result of this desirable structure, these mesoporous Li4Ti5O12-x/C submicrospheres exhibit comprehensively improved electrochemical performances. The optimized sample, with an ideally graded sphere-size distribution ranging from 100 nm to 600 nm, shows the largest tap density of 1.71 g cm(-3), high first cycle Coulombic efficiency of 95.0% and 4.5 mV lower working potential. At 10 C, its capacity is as high as 119 mA h g(-1) with capacity retention of 95.9% over 100 cycles.

Monodispersed mesoporous Li4Ti5O12 submicrospheres as anode materials for lithium-ion batteries: morphology and electrochemical performances.

Although nanosizing Li4Ti5O12 (LTO) materials is an effective way to improve their rate performances, their low tap density and first cycle coulombic efficiency limit their practical applications. To tackle these problems while preserving the advanced rate performances, monodispersed mesoporous LTO submicrospheres are developed here. These submicrospheres are synthesized via a solvothermal method using TiO2 submicrospheres and LiOH as precursors followed by a mild calcinations. The roles of the solvent used in the solvothermal process and calcination temperature are systematically investigated and optimized. The LTO submicrospheres fabricated by the solvothermal process using a water-ethanol (60 vol%) solvent followed by a calcination process at 600 °C reveal a large sphere size of 660 ± 30 nm with a small primary particle size of 20-100 nm, a large specific surface area of 15.5 m(2) g(-1), an appropriate pore size of 4.5 nm and an ultra-high tap density of 1.62 g cm(-3). Furthermore, they show high crystallinity and no blockage of Li(+) ion transportation pathways. Due to the novel morphology and ideal crystal structure, these submicrospheres exhibit outstanding electrochemical performances. They display a high first cycle coulombic efficiency of 93.5% and a high charge capacity of 179 mA h g(-1) at 0.5 C between 1.0 and 2.5 V (vs. Li/Li(+)), surpassing the theoretical capacity of LTO. Their charge capacity at 10 C is as high as 109 mA h g(-1) with a capacity retention of 97.8% over 100 cycles. Therefore, this LTO material can be a superior and practical candidate for the anodes of high-power lithium-ion batteries.

A Facile Supercritical Alcohol Route for Synthesizing Carbon Coated Hierarchically Mesoporous Li4Ti5O12 Microspheres

Hierarchically mesoporous Li4Ti5O12 (LTO) microspheres with a conductive layer coating are considered one of most promising structures to enhance high-rate performance as well as to retain high vol...

Mesoporous Li4Ti5O12 nanoclusters as high performance negative electrodes for lithium ion batteries

Porous Li4Ti5O12 nanoclusters with high surface area are synthesized by a facile solution-based method followed by low-temperature calcination. The Li4Ti5O12 nanoclusters present the key characteristics needed to serve as high-performance negative electrodes for lithium ion batteries, including nano-sized dimension of the Li4Ti5O12 clusters (50–100 nm) for short ion and electron transfer path, and high surface area (142 m2 g−1) with mesoporosity (pore diameter 2–6 nm) for easy access to the electrolyte and efficient ion transport. Based on these characteristics, the Li4Ti5O12 electrode delivers an initial capacity of 173 mAh g−1 at the rate of 0.5 C, comparable to its theoretical capacity. Excellent cycling stability at high rates is achieved in the Li4Ti5O12 electrode, offering potential to serve as a negative electrode material for high rate lithium ion battery applications.

Facile synthesis of hierarchical mesoporous Li4Ti5O12 microspheres in supercritical methanol

A facile, template-free route using supercritical methanol for the preparation of hierarchical mesoporous Li4Ti5O12 spinel microspheres in a very short reaction time is introduced. Nanosized, primary Li4Ti5O12 particles (5–10 nm) are loosely aggregated and form micron-sized, secondary mesoporous spheres (0.2–2.0 μm) with a pore size of 2–10 nm. Subsequent calcination of the as-synthesized Li4Ti5O12 at a low temperature of 600 °C results in excellent long-term cyclability and high rate performance. The discharge capacity after 400 cycles at 1 C is 134.9 mAh g−1 (77.6% of the initial discharge capacity), and the discharge capacity at 10 C is 108.5 mAh g−1. The formation mechanism of hierarchical mesoporous microspheres in supercritical methanol is discussed.

Nitridated mesoporous Li4Ti5O12 spheres for high-rate lithium-ion batteries anode material

Nitridated mesoporous Li4Ti5O12 spheres were synthesized by a simple ammonia treatment of Li4Ti5O12 derived from mesoporous TiO2 particles and lithium acetate dihydrate via a solid state reaction in the presence of polyethylene glycol 20000. The carbonization of polyethylene glycol could effectively restrict the growth of primary particles, which was favorable for lithium ions diffusing into the nanosized TiO2 lattice during the solid state reaction to form a pure phase Li4Ti5O12. After a subsequent thermal nitridation treatment, a high conductive thin TiOxNy layer was in situ constructed on the surface of the primary nanoparticles. As a result, the nitridated mesoporous Li4Ti5O12 structure, possessing shorter lithium-ion diffusion path and better electrical conductivity, displays significantly improved rate capability. The discharge capacity reaches 138 mAhg(-1) at 10 C rate and 120 mAhg(-1) at 20 C rate in the voltage range of 1-3 V.