Spinel Li4Ti5O12 Research Articles

Optimized Solid-State Reaction Process of Synthesizing Li4Ti5O12 with Improved Rate Capability for Li-Ion Batteries

Spinel Li4Ti5O12 (LTO) has been actively studied due to its predominant properties in safety issue. LTO can be synthesized by different synthesis techniques including solid-state reaction, sol-gel, high energy ball milling, hydrothermal method, spray pyrolysis, etc. Among these synthesizing methods, the solid-state reaction method is the most commercially available process. It is very important to reduce calcination temperature and time in mass production using solid-state reaction. We prepared several sets of LTOs using commercially available precursors (TiO2) which have various particle sizes. We also varied calcination temperature in each fixed TiO2 particle size. We found the optimum process condition that has the best electrochemical properties. The sizes of the TiO2 precursors are 15 nm, 25 nm, 32 nm, and 40 nm. The calcination temperatures are 700 °C, 750 °C, 800 °C, and 850 °C. The calcination time (36 hr) is too long to prepare single phase LTO at 700 °C. The single phase LTOs are obtained in all the size of the used TiO2 particle at 800 °C and 850 °C, but the LTO particles are 1 ~ 2 um, which is too large. The pure LTOs are synthesized in all the TiO2 particle size except for 15 nm at 750 °C. The calcination time was varied from 36 hr to 1hr. The rate performance is conducted in all the fabricated samples. When the calcination time is 36hr, the best capacity is obtained in the sample, which 32 nm TiO2 particle is used. At 50 C, the capacity of the sample was 88 mAh/g when the 32 nm TiO2 precursor is used. The synthesized LTO at 750 °C shows best capacity of 122 mAh/g when the calcination time is 1 hr. The best electrochemical performance was due to small particle size, resulting in fast Li-ion diffusion and larger contact area between particles. We also fabricated Li-ion capacitor using the LTO and investigated the electrochemical behaviors.

Enhanced Electrochemical Performance of Li4Ti5O12 Anode for Lithium Ion Batteries with Titanate Coupling Reagent As Electrolyte Additive

With the increasing applications of lithium ion batteries in energy storage, electric vehicles and hybrid electric vehicles, it’s required to improve the energy density, safety, rate capability and cycling stability of the batteries. Spinel Li4Ti5O12 is a promising anode material for lithium-ion batteries which possesses good Li+ insertion and de-insertion reversibility with negligible structure change, high safety and rate capability, excellent cycle stability1-2. While the theoretical capacity of it, 175 mAh g-1, is slightly low. Meanwhile, it’s observed gassing during storage or cycling3, limitting its application.It was found that the surface coating could be an effective method to solve the swelling problem and be beneficial to the electrochemical performance4. In this paper, we investigated the effect of titanate coupling reagent TCA-K38S as electrolyte additive on the performance of Li4Ti5O12. TCA-K38S, isopropyl tri-(dioctylpyrophosphate) titanate, is a liquid monoalkoxy pyrophosphate titanate, usually used as coupling agent not only finorganic fillers with resins, but also fnon-polar materials with polar materials, the structural formula is shown in Fig.1. The electrolyte used in this work are 1.2 mol LiPF6 in EC/ EMC solvents ((3:7 by volume), the TCA-K38S was added at 1wt.% and 3 wt.% to the electrolyte solution. Fig.2 shows the cycling performance of Li4Ti5O12 batteries with different amounts of the TCA-K38S additive at various rates. It can be seen that the specific capacity of batteries with 1wt.% additive is 180 mAh g-1 at the first discharge and stable in 170mAh g-1 at 0.2 C, comparied to 162mAh g-1 and 158mAh g-1 at 0.2 C when it’s without additives. Acknowledgements The project was supported by the National High Technology Research and Development Program of China (863) (2013AA050902) and Shanghai Science and Technology Development Fund (15DZ2282000, 14JC1491800) .

Nanoparticles-Constructed Spinel Li4Ti5O12 with Extra Surface Lithium Storage Capability towards Advanced Lithium-ion Batteries

Spinel Li4Ti5O12 (LTO) has been intensively investigated as promising anode material for large-scale stationary electrochemical storage of energy produced from renewable sources due to its remarkable structural stability and excellent safety. In this paper, nanoparticles-constructed LTO with extra surface lithium storage capability is successfully prepared in air at 600°C via employing TiOSO4·2H2O as Ti source. The newly prepared nanoparticles-constructed LTO displays enhanced electrochemical performances, demonstrating ultrahigh reversible capacity of 173mAhg−1 at 0.5C and superior rate performance of more than 145mAhg−1 at 30C between 1.0 and 2.5V vs. Li+/Li. The influences of specific surface area and crystallinity on the extra surface lithium storage capability of the sintered samples for LIBs are investigated in detail in terms of reversible capacity, cyclability and rate capability. Our results reveal that not only specific surface area but also crystallinity and pored structure are vital for reducing electrode polarization and achieving extra surface lithium storage of LTO. We anticipate that the uniquely extra surface lithium storage reaction of LTO will get more attentions in the near future.

Discriminating the Mobile Ions from the Immobile Ones in Li4+xTi5O12: 6Li NMR Reveals the Main Li+ Diffusion Pathway and Proposes a Refined Lithiation Mechanism

One of the most widely known anode materials with excellent cycling performance in lithium-ion batteries is zero-strain lithium titanate Li4Ti5O12 (LTO). This is based on the highly reversible insertion and deinsertion of Li ions varying the composition of Li4+xTi5O12 from x = 0 to x = 3. The facile incorporation of Li is tightly connected with bulk Li ion dynamics. Although macroscopic electrochemical properties have been studied in great detail, bulk Li ion diffusion pathways have rarely been probed experimentally from an atomic scale point of view. Here, we evaluated 1D and 2D 6Li magic angle spinning (MAS) NMR spectra recorded as a function of x to make the local magnetic changes during Li insertion visible. This enabled us to directly show that rapid Li exchange involves the 8a and 16c sites, forming a 3D network throughout the LTO spinel structure. In contrast, considering the time scale set by our NMR experiments, the Li ions residing on the mixed occupied octahedral positions 16d are quite immobil...

Li4Ti5O12/reduced graphene oxide composite as a high-rate anode material for lithium ion batteries

Considering spinel Li4Ti5O12 (LTO) and reduced graphene oxide (rGO) both have own unique natural performance advantages separately, so we utilize a facile hydrothermal route to fabricate a composite which is synthesized by the spinel LTO grown on the rGO sheets. Electrochemical tests reflect that the small ratio of rGO (about 6.2wt %) plays a key role in the improvement of the original morphology, structure and high rate performance. Compared with the previously published LTO/rGO composite, the newly synthesized LTO/rGO composite delivers a higher reversible special capacity of 196.4mAhg−1 at 1C and even exhibits good cycle stability with 98.1% retention after 100 cycles. What’s more, after cycling 500 times at 20C, the discharge capacity of composite retains 154.5mAhg−1 (96.5% retention), whereas the bare LTO is only 69mAhg−1 (79.7% retention). In addition, the Li4Ti5O12/rGO composite possesses fine high rate performance with the specific discharge capacities of 175.3mAhg−1(at 10C), 167mAhg−1 (at 15C) and 160.1mAhg−1(at 20C). Such electrochemical performance is attributed to its unique structure of conductive rGO sheets with clung Li4Ti5O12 particles.

New Insights on Li4Ti5O12 Electrode/Electrolyte Interfaces: A X-Ray Photoelectron Spectroscopy and Scanning Auger Microscopy Study

Spinel Li4Ti5O12 (LTO) is considered as a good alternative negative electrode material for Li-ion batteries [1], due to its negligible change of lattice parameter during insertion/extraction of lithium ions [2], resulting in a very low capacity decrease upon cycling. However, the reactivity of LTO toward commons carbonates based electrolytes has been evidenced by surface analysis [3] and an important gassing occuring at the electrode/electrolyte interface was reported [4]. Therefore it is essential to better understand the interfacial phenomenons. This work aims to achieve a precise understanding of the LTO electrode/electrolyte interfaces in relation with batteries electrochemical performances. The influence of various parameters (cycling temperature, electrode and electrolyte composition, cycling potential window) upon the solid electrolyte interphase (SEI) formation and dissolution through the first cycle was systematically investigated. The evolution of those interfaces after long cycling is currently being studied. Finally, Li4Ti5O12/LiMn2O4cells having potential assets in term of cost and safety [5], will be investigated, in order to point out the changes in the SEI formation due to interactions between the two electrodes. The samples are analysed by X-ray Photoelectron Spectroscopy (XPS) and Scanning Auger Microscopy (SAM), two complementary extreme surface characterization techniques (analysis depth 5-10 nm), operating at different spatial resolutions. The galvanostatic curves obtained for the Li4Ti5O12/Li half-cells first cycle at room temperature and at 85°C are presented on figure 1. The number of electrons exchanged per unit formula (Li4Ti5O12) at the end of the first discharge increases with the temperature indicating that more electrons are exchanged at higher temperatures to reach the same state of charge. The irreversible capacity also increases with the temperature at the first cycle. Those electrochemical results are directly correlated with the increase of the SEI thickness with the temperature, as observed by XPS and SAM experiments at the end of the first discharge. Indeed at room temperature, the two components doublets in the titanium spectrum (figure 2a) indicate a partial reduction of titanium ions consecutive to lithium insertion. The component at low binding energy in oxygen spectrum (figure 2b) is characteristic of oxygen ions in the LTO material, while the ones at higher binding energy reveal the presence of deposited species at the electrode surface. In addition to the components characteristic of PVdF binder and carbon black (CB) constituents of the electrode, carbon spectrum (figure 2c) presents components characteristic of C-O, O-C=O and CO3 chemical environments, confirming the formation of a SEI resulting from the degradation of electrolyte species. By contrast, at 85°C titanium and the component attributed to oxygen anions from the LTO lattice are not detected (figure 2c and 2d), meaning that the SEI is thicker than the XPS depth of analysis. The intensity decrease of the carbon black component (figure 2f) together with the intensity increase of C-O component, compared to room temperature, is consistent with an increase of the SEI thickness. The morphology of the electrode surface have been characterized by SEM (Figure 3a and 3c) and allow to identify LTO particles in light grey and carbon black aggregates in dark grey, for both temperatures. In contrast, the carbon elemental SAM mappings at room temperature (figure 3b) displays a higher carbon concentration on top of carbon black aggregates, whereas the mapping at 85°C (figure 3d) evidences a more homogeneous carbon distribution on top of the electrode, indicating a complete covering of the electrode surface by the SEI species. [1] J. B. Goodenough, Journal of the American Chemical Society 135 (4) (2013) 1167–1176. [2] K. Zaghib, Journal of Power Sources 196 (8) (2011) 3949–3954. [3] L. El Ouatani, Journal of The Electrochemical Society 156 (6) (2009) A468. [4] Y.-B. He, Scientific Reports 2. [5] I. Belharouak, Journal of the Electrochemical Society 159, A1165–A1170 (2012). Figure 1

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.

Effect of starting materials on electrochemical performance of sol-gel-synthesized Li4Ti5O12 anode materials for lithium-ion batteries

In this study, the effect of the sol-gel starting materials with different particle sizes on the sol-gel-synthesized spinel Li4Ti5O12 (LTO) was systematically investigated. The physical and electrochemical properties of the synthesized materials were characterized by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller-specific surface area analyses, galvanostatic charge/discharge tests, cyclic voltammetry, and electrochemical impedance spectroscopy. It was found that the initial particle size of sol-gel starting material played a crucial role on the properties of as-prepared LTOs. The LTO synthesized with the relatively finer particle size of starting materials possessed relatively smaller particle size and larger specific surface area and therefore resulted in the superior electrochemical properties. The initial discharge capacity of the as-prepared LTO exhibited 168.2, 150.6, and 142.7 mAh g−1 at current densities of 1, 5, and 10 C, respectively, and up to 95, 95, and 90 % of the corresponding initial discharge capacity was retained after 50 cycles.

Nano-particle size effect on the performance of Li4Ti5O12 spinel

The effect of nano-scale particle size on the performance of Li4Ti5O12 (LTO) electrode is investigated by computational simulation. Newman pseudo-2D (P2D) model is utilized to characterize the performance of LTO electrode. However, unlike previous P2D lithium ion battery (LIB) models, the model design adjustable parameters are set based on the experimental data obtained from monodispersed active electrode particles. This allows the model to accurately reflect real battery performance. The model provides the optimum nano-particle size for a specific application, which eliminates the performance loss due to the limited mass transportation. The model can be employed for a wide range of electrode materials to optimize the particle-size and reduce fabrication costs by avoiding unnecessary particle size reduction.

Li4Ti5O12 on Graphene for High Rate Lithium Ion Batteries

Spinel Li4Ti5O12 has been considered as a promising anode material to substitute graphite in lithium ion batteries (LIBs) for large scale electrical energy storage due to its high safety and long cycling stability. However, the drawback of its poor rate performance still hinders it from wide practical application. In this study, with the aim to solve this issue, we have designed a wrinkled graphene layer between the active spinel Li4Ti5O12 and aluminum current collectors by a blade coating method. This introduced wrinkled graphene layer provides larger contact area, lower contact resistance, stronger adhesion and better electrode stability of Li4Ti5O12 electrode. As a result, the rate performance of spinel Li4Ti5O12 has been significantly improved, without compromising its other properties.

Study of the interface between Na-rich and Li-rich phases in a Na-inserted spinel Li4Ti5O12 crystal for an electrode of a sodium-ion battery.

Spinel lithium titanate (LTO; Li4Ti5O12) is one of the promising materials for negative electrodes of sodium-ion batteries (SIBs). The stable charge-discharge performance of SIB cells using LTO electrodes depends on the reversible Na insertion-extraction mechanism of LTO, where the spinel lattice is expanded with Na insertion, and two phases, Na-inserted LTO (Na-LTO) and Li-inserted LTO (Li-LTO) phases, are generated. These phases are confirmed using X-ray diffraction (XRD), while the mechanism of the two-phase coexistence with different lattice volumes is yet unclear. Here, we investigate the detailed morphology of the coexisting Na-LTO and Li-LTO phases using in situ XRD measurements and high-resolution transmission electron microscopy (TEM) observation. Na-LTO (a = 8.74 Å) and Li-LTO (a = 8.36 Å) phases are confirmed in both the electrochemically formed Na-inserted LTO electrode and the single-crystalline LTO thin specimen. We observed that the Na-LTO/Li-LTO interface is parallel to the (001) plane, and contains an inevitable lattice mismatch along the interface, while the expansion of the Na-LTO phase can be partially relaxed normal to the interface. We observed that the Na-LTO/Li-LTO interface has interface layers of lattice disordering with a 1-2 nm width, relaxing the lattice mismatch, as opposed to results from the previous scanning TEM observation. How the different lattice volumes at the two-phase interface are relaxed should be the key issue in investigation of the mechanism of Na insertion and extraction in LTO electrodes.

Choosing the best molecular precursor to prepare Li4Ti5O12 by the sol-gel method using (1)H NMR: evidence of [Ti3(OEt)13](-) in solution.

(1)H NMR spectroscopy at 400 MHz in toluene-d8 of evaporated mixtures of lithium ethoxide and titanium(iv) isopropoxide in ethanol, used to prepare the spinel Li4Ti5O12 by the sol-gel method, may help clarify why the atomic ratio 5Li : 5Ti and not 4Li : 5Ti is the right choice to obtain the pure phase when performing hydrolysis at room temperature. The mixtures xLiOEt/yTi(OPr(i))4 in ethanol undergo alcohol exchange at room temperature, and the evaporated residues contain double lithium-titanium ethoxide [LiTi3(OEt)13] rather than simple mixtures of single metal alkoxides; this is of great relevance to truly understanding the chemistry and structural changes in the sol-gel process. Detailed inspection of the (1)H and (13)C VT NMR spectra of mixtures with different Li/Ti atomic ratios unequivocally shows the formation of [LiTi3(OEt)13] in a solution at low temperature. The methylene signals of free lithium ethoxide and Li[Ti3(OEt)13] coalesce at 20 °C when the atomic ratio is 5 : 5; however, the same coalescence is only observed above 60 °C when the atomic ratio is 4 : 5. We suggest that the highest chemical equivalence observed by (1)H NMR spectroscopy achieved through chemical exchange of ethoxide groups involves the highest microscopic structural homogeneity of the sol precursor and will lead to the best gel after hydrolysis. Variable temperature (1)H NMR spectra at 400 MHz of variable molar ratios of LiOEt/Ti(OPr(i))4 are discussed to understand the structural features of the sol precursor. While the precursor with the atomic ratio 5Li : 5Ti shows no signal of free LiOEt at 20 °C, both 4Li : 5Ti and 7Li : 5Ti show free LiOEt at 20 °C in their (1)H NMR spectra, indicating that the molar ratio 5Li : 5Ti gives the maximum rate of chemical exchange. DFT calculations have been performed to support the structure of the anion [Ti3(OEt)13](-) at room temperature.

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.

Conductivity Enhancement and Thin-Film Processing of Li4Ti5O12(LTO) Spinel for Li Battery Applications

Spinel Li4Ti5O12 has been considered as one of the most prospective anode materials for Li-ion microbatteries. Homogeneous and crack-free Li4Ti5O12 film with thickness around 200 nm have been deposited on Pt/Ti/SiO2/Si(100) substrate by r.f. magnetron sputtering. The influence of the post-annealing treatment on the phase composition, structure and electrochemical behavior was studied. The Li/Ti molar ratio in the films decreased with an increasing oxygen fraction. The amount of Li4Ti5O12 phase increases with the annealing temperature increasing from 500°C to 700°C. Electrochemical characterization of samples treated at 600°C presents a redox reaction around 1.55 V indicating that the film contains Li4Ti5O12 spinel. Larger capacity and good reversibility in the sample post-annealing treatment at 600 °C can be attributed to high crystallinity of Li4Ti5O12 and amorphous TiO2 phase.

Synergistic effects of coating and doping for lithium ion battery cathode materials: synthesis and characterization of lithium titanate-coated LiCoO2 with Mg doping

Lithium titanates are introduced as coating materials on the surface of Mg-doped LiCoO2 in which the residual Li2CO3 after synthesis of the active materials is used as a lithium source. It is revealed that two completely different lithium titanate phases (monoclinic Li2TiO3 and spinel Li4Ti5O12) can be obtained as the coating materials depending on the concentration of a titanium source. Characterization of the coating materials is performed with various experimental techniques including XRD, nano SIMS, TEM, EELS and current measurement using nano probe. The Li4Ti5O12 coating layer from the high concentration of titanium source secures better electrochemical performances than the Li2TiO3 one from the low concentration of titanium source due to its “zero-strain” characteristic. In addition, it is shown that the doped ions (Mg2+) from the active materials move to the coating layer and strongly enhance the conductivity of Li4Ti5O12. Consequently, synergistic effects on the cell performances of cyclability and rate capability from coating and doping for the LiCoO2 cathode materials are rigorously investigated.

Preparation and characterisation of porous lithium titanate thin film by magnetron sputtering

This work introduces a facile solution method for preparation of porous Li4Ti5O12 (LTO) thin film electrode for lithium-ion batteries (LIBs). The porous LTO films were prepared by magnetron sputtering deposition using cubic spinel LTO powder target as a sputtering source. The microstructure and morphology of the LTO thin films annealed in air (LTO-air) was porous structured thin film. The LTO-air thin film electrode showed the excellent electrochemical performance. The capacity of LTO-air up to 81 μAh cm−2μm was at 10 μA cm−2, and capacity retention was 99% after 100 cycles at 10 μA cm−2. The porous structure features of thin film likely contributed to the good electrochemical performance of the LTO-air thin film. This research suggests that LTO thin films have the potential for the high energy storage electrode material for LIBs.

Unveiling the Fabrication of “Rocking-Chair” Type 3.2 and 1.2 V Class Cells Using Spinel LiNi0.5Mn1.5O4 as Cathode with Li4Ti5O12

We first report the possibility of using spinel LiNi0.5Mn1.5O4 (LNM) nanofibers as cathode for constructing high (∼3.2 V) and low (∼1.2 V) voltage “rocking-chair” type Li-ion cells with spinel Li4Ti5O12 (LTO) by utilizing Li-insertion into tetrahedral (Ni2+/4+) and octahedral (Mn4+/3+) sites of LNM. We also explored the possibility of constructing symmetric cells (LNM/LNM) with a working potential of ∼1.8 V. Among the three configurations investigated, LNM/LTO (electrochemically prelithiated) is found superior in terms of high rate capability, cyclability, and good capacity retention characteristics. High performance spinel LNM nanofibers are prepared via a scalable electrospinning technique and their Li-insertion properties are evaluated in half-cell assembly. The half-cell studies are used for adjusting the mass balance while fabricating “rocking-chair” Li-ion cells.

Carbon-Coated Li4Ti5O12 as Anode Material for Sodium-Ion Batteries.

The surface-coating of carbon was performed on the spinel Li4Ti5O12 materials for the electrochemical sodium insertion in sodium ion battery application. The carbon-coated Li4Ti5O12 was synthesized by using the citric acid sol-gel method. Carbon-coated Li4Ti5O12 exhibits superior cycle performance as well as the rate capability in comparison to the pristine Li4Ti5O12. Electrochemical impedance spectroscopy analyses also reveal that surface modification with carbon suppresses the increase in resistance concerning charge transfer reaction as well as solid electrolyte interface layer formation during cycle test.

High Performance Li₄Ti₅O12/Si Composite Anodes for Li-Ion Batteries.

Improving the energy capacity of spinel Li4Ti5O12 (LTO) is very important to utilize it as a high-performance Li-ion battery (LIB) electrode. In this work, LTO/Si composites with different weight ratios were prepared and tested as anodes. The anodic and cathodic peaks from both LTO and silicon were apparent in the composites, indicating that each component was active upon Li+ insertion and extraction. The composites with higher Si contents (LTO:Si = 35:35) exhibited superior specific capacity (1004 mAh·g−1) at lower current densities (0.22 A·g−1) but the capacity deteriorated at higher current densities. On the other hand, the electrodes with moderate Si contents (LTO:Si = 50:20) were able to deliver stable capacity (100 mAh·g−1) with good cycling performance, even at a very high current density of 7 A·g−1. The improvement in specific capacity and rate performance was a direct result of the synergy between LTO and Si; the former can alleviate the stresses from volumetric changes in Si upon cycling, while Si can add to the capacity of the composite. Therefore, it has been demonstrated that the addition of Si and concentration optimization is an easy yet an effective way to produce high performance LTO-based electrodes for lithium-ion batteries.

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.