Electrochemical Performance Of Li4Ti5O12 Research Articles

Laser assisted method for synthesis Li4Ti5O12/polyether sulfone composite for lithium ion batteries anodic materials

Spinel Li4Ti5O12 (LTO) is a potential anode material for innovative high-power lithium-ion batteries (LIBs) because of its "zero strain" features during quick charging/discharging, extended cycle life, and elevated rate capability. However, LTO has limited application due to its poor ionic/electronic conductivity and slow ionic diffusion coefficient. In this work, LTO/polyether sulfone (PES) composite is synthesized via pulsed laser ablation in liquid media technique based on an infrared Nd:YAG nanosecond laser. The influences of laser ablation power were used to vary the particle sizes of the generated LTO nanoparticles on the formation of the LTO/PES structure, followed by the electrochemical performances of LTO. Various methods were used to investigate the composite's structural, optical, and morphological properties. The interactions between the polymer and nanoparticles, as well as the fine dispersion of NPs, were evident in the optical tests, which showed that the absorbance greatly improved and the energy band gap decreased. Also, the morphological images display the cubic shape of pure LTO NPs with varying particle sizes between 5 and 26 nm as the laser power changes. Furthermore, from XRD characterization, the intensity of this crystalline peak of PES decreases as a function of LTO wt. % increase without appearing of any other impurities. After that, the electrochemical performances were tested for all prepared samples, which showed that the as-prepared composite structure with a lower particle size exhibits excellent electrochemical performances. This result demonstrates that providing surface defects by forming Ti3+/Ti4+ pairs and oxygen vacancies in LTO is a successful method for increasing ion/electron mobility. This method can be applied to improve the battery efficiency of other substances with low ionic conductivities in the developed batteries.

Li4Ti5O12/C Composite Anode Material Synthesized Involving Absorbent Cotton for Li-Ion Battery

A puissant specific capacity spherical Li4Ti5O12 anode material of Lithium-Ion battery was successfully synthesized by two methods include a high-temperature solid-phase method using solid phase lithium and titanium sources, and a sol-gel method with liquid phase lithium and titanium sources. The carbon coating modification of Li4Ti5O12 anode material was carried out by adding absorbent cotton during the reaction process, and the effect of absorbent cotton addition on the structure, morphology and electrochemical performance of Li4Ti5O12 was studied. The composite prepared by sol-gel represents a superior first discharge specific capacity of 173 mAh·g−1 at 0.2 C rates, approximately 68 mAh·g−1 at 10 C rates, and the capacity of sample remained 103 mAh·g−1 after 100 cycles of 1 C rate charge/discharge process.

Temperature effects on electrochemical performance of Li4Ti5O12

Li4Ti5O12(LTO) is one of the most popular [Formula: see text]-storage anode materials. However, the influences of different operating temperatures on the electrochemical performance of LTO and the underlying mechanisms are still unclear. Herein, we systematically investigate its temperature-dependent electrochemical performance, electrochemical kinetics, and crystal-structural evolution at −10[Formula: see text]C, [Formula: see text]C, [Formula: see text]C, [Formula: see text]C, and [Formula: see text]C. When the operation temperature increases from −10[Formula: see text]C to [Formula: see text]C, more intensive electrolyte decomposition increases the irreversible capacity in the first cycle, which decreases the initial Coulombic efficiency. Meanwhile, the electrochemical kinetics becomes faster, leading to reduced electrode polarization, faster [Formula: see text]Transport, and higher rate capability. Finally, the maximum unit-cell-volume shrinkage enlarges, resulting in the decay of the cyclic stability. However, when the temperature further rises to 60°C, the rate capacity and cyclic stability rapidly decay due to the severe electrolyte decomposition catalyzed by [Formula: see text] and the formation of thick solid electrolyte interface (SEI) films.

Enhancing battery performance by glucose addition to form spherical Li4Ti5O12 as an anode material

A high specific capacity spherical Li4Ti5O12 anode material of Lithium-Ion battery was successfully synthesized by a high-temperature solid-phase method consisting of ball milling, spray drying and calcination processes. Its suitable reaction conditions were explored by the orthogonal experiment method, and the effect of glucose addition on the morphology and electrochemical performance of Li4Ti5O12 was studied. The addition of glucose could change the surface structure of Li4Ti5O12, improve its conductivity, therefore enhance its electrochemical performance. The prepared lithium titanate represents a superior specific capacity of 163 mAh·g−1 at 0.2 C rates, approximately 65 mAh·g−1 under 10 C rates, and the capacity retention rate of sample remained 97.55% after 100 cycles of charging/discharging process.

The Stabilizing Effect of Li4Ti5O12 Coating on Li1.1Ni0.35Mn0.55O2 Cathode for Liquid and Solid–State Lithium-Metal Batteries

Li–rich layered cathode materials with high energy density suffer from severe capacity decay during cycling, which is associated with volume change and electrolyte corrosion during (de)lithiation. A Li+ ionic conducting Li4Ti5O12 coating with high structural integrity is developed on Li1.1Ni0.35Mn0.55O2 cathodes via a dry powder coating method. The electrochemical performances of Li4Ti5O12–coated Li1.1Ni0.35Mn0.55O2 cathodes in liquid and solid–state lithium batteries were investigated. The initial discharge capacity of Li4Ti5O12–coated Li1.1Ni0.35Mn0.55O2 in the liquid electrolyte has been improved from 116.5 mA h g−1 to 123.7 mA h g−1 at 0.1°C. An impressive cyclability with a high capacity retention of 89.3% was achieved in solid–state lithium batteries. These results demonstrate that the Li4Ti5O12 coating plays an essential role in enhancing the specific capacity and better performance for Li1.1Ni0.35Mn0.55O2 cathode.

The effect of sodium and niobium co-doping on electrochemical performance of Li4Ti5O12 as anode material for lithium-ion batteries

The effect of sodium and niobium co-doping on electrochemical performance of Li4Ti5O12 as anode material for lithium-ion batteries

In-situ self-assembly synthesis of low-cost, long-life, shape-controllable spherical Li4Ti5O12 anode material for Li-ion batteries

Li4Ti5O12 (LTO) is the most promising anode material for lithium-ion batteries owing to its excellent cycle stability and safety. However, the electrochemical performance of LTO at high rates is limited by its low conductivity. Generally, LTO preparation requires organic titanium sources, which are expensive. In this study, inexpensive H2TiO3 was used as the titanium source, LiOH‧H2O served as the lithium source, and NH3‧H2O was added to control the pH of the solution. Simple one-step liquid-phase deposition and calcination were performed for obtaining in situ self-assembled LTO submicron spheres with stable morphology and excellent electrochemical performance. According to electrochemical performance tests, the sample calcined with 4 mL of 25% NH3‧H2O at 700 °C (LTO-4–700) exhibited the best performance. Its discharge capacity remained at 176.4 mAh g−1 over 100 cycles at 87.5 mA g−1 and retained at 136.7 mAh g−1 over 500 cycles at 875 mA g−1, and its specific capacity was 105.6 mAh g−1 over 1000 cycles, even at a current of 1750 mA g−1 with a retention rate of 96.7%. Furthermore, LTO-4–700 exhibited excellent rate performance at 3500 mA g−1 compared to other samples. Cyclic voltammetry and electrochemical impedance spectroscopy confirmed that submicron spherical LTO-4–700 had a high Li+ migration rate and low electrochemical impedance.

Multi-length-scale x-ray spectroscopies for determination of surface reactivity at high voltages of LiNi0.8Co0.15Al0.05O2 vs Li4Ti5O12.

The surface evolution of LiNi0.8Co0.15Al0.05O2 (NCA) and Li4Ti5O12 (LTO) electrodes cycled in a carbonate-based electrolyte was systematically investigated using the high lateral resolution and surface sensitivity of x-ray photoemission electron microscopy combined with x-ray absorption spectroscopy and x-ray photoelectron spectroscopy. On the cathode, we attest that the surface of the pristine particles is composed of adventitious Li2CO3 together with reduced Ni and Co in a +2 oxidation state, which is directly responsible for the overpotential observed during the first de-lithiation. This layer decomposes at 3.8 V vs Li+/Li, leaving behind a fresh surface with Ni and Co in a +3 oxidation state. The charge compensation upon Li+ extraction takes place above 4.0 V and is assigned to the oxidation of both Ni and oxygen, while Co remains in a +3 oxidation state during the whole redox process. We also identified the formation of an inactive surface layer already at 4.3 V, rich in reduced Ni and depleted in oxygen. However, at 4.9 V, NiO-like species are detected accompanied with reduced Co. Despite the highly oxidative potential, the surface of the cathode after long cycling is free of oxidized solvent byproducts but contains traces of LiPF6 byproducts (LiF and POxFy). On the LTO counter electrode, transition metals are detected only after long cycling vs NCA to 4.9 V as well as PVdF and LiPF6 byproducts originating from the cathode. Finally, harvested cycled electrodes prove that the influence of the crosstalk on the electrochemical performance of LTO is limited.

Modification of Li4Ti5O12 Anodes Using Epoxy‐Functionalized Silane to Improve Electrochemical Performance in Lithium‐Ion Batteries

The spinel Li4Ti5O12 (LTO) material, especially because of the small particle sizes of LTO, has a high tendency toward adhesion and aggregation of particles due to the large cohesive forces, thereby deteriorating its electrochemical performance. To overcome this drawback, LTO is modified with epoxy‐functionalized silane KH560 by a simple hydrolysis method. This process successfully achieves the KH560 modifying layer. Specifically, the effects of KH560 on the dispersion and electrochemical performance of LTO are investigated. The results show that KH560–LTO (0.5 wt%) can be stabilized and evenly dispersed, thus narrowing the particle size distribution, distributing the particles homogeneously in the electrode sheet, and reducing the viscosity change of the slurry. From the electrochemical measurements, KH560–LTO (0.5 wt%) exhibits higher initial discharge capacity (168.3 mAh g−1 at 2 C) and better rate capability (133.2 mAh g−1 at 10 C). In addition to this, the specific capacity of the KH560–LTO (0.5 wt%) sample remains at 149.2 mAh g−1 after 100 cycles at 5 C. This excellent electrochemical performance is attributed to the fact that the KH560 modifying layer can effectively promote the dispersion of particles.

Disclosing the Complex Surface Reactivity of LiNi0.8Co0.15Al0.05O2 at High Potential By Combining XPEEM, XAS and XPS Measurements

The development of the next generation high-energy density Li-ion batteries requires a deep understanding on the interface between high voltage cathode and electrolyte. When cathode materials are cycled to high potential, especially above 4.3 V vs. Li+/Li, different reactions can take place at the cathode-electrolyte interface: electrolyte oxidation1, surface structural changes, dissolution of the transition metals (TMs)2, oxygen oxidation3 and release4, and binder degradation5. Moreover, all those parasitic reactions can also affect the counter electrode via a "cross-talk" process of organic/inorganic species and TMs. To elucidate these complex reaction mechanisms, a combination of different spectroscopy techniques is required in order to have full picture of the interface reactivity. Although X-ray photoelectron spectroscopy (XPS) provides valuable knowledge concerning the binder and electrolyte stability, information about the TMs oxidation states and the surface structure are more difficult to obtain. On the other hand, X-ray absorption spectroscopy (XAS) of TM L-edges, C K and O K-edges provides very important knowledge on the oxidation states and structural evolution during cycling. By combining the high lateral resolution and surface sensitivity of X-ray photoemission electron microscopy (XPEEM)6 with total electron yield (TEY) and total fluorescence yield (TFY), one can gain a better understanding of the evolution of both the surface and the bulk of the particles. In this contribution, we show the successful combination of XPS, XPEEM and XAS in TEY and TFY modes to elucidate the complex surface reactivity of LiNi0.8Co0.15Al0.05O2 (NCA) when it is cycled versus Li4Ti5O12 (LTO), especially at 4.9 V vs. Li+/Li in LP30 electrolyte. Our results show the instability at high potential of the organic binder contained in the electrodes and the LiPF6 salt in the electrolyte, while EC:DMC oxidation byproducts are not observed on neither the cathode nor the anode despite the high potential. Reduced Ni is detected on the NCA surface and, due to the limited oxygen release observed from the NCA material7, reversible oxygen oxidation is observed in the O K-edge spectra at the NCA surface, proving the participation of O together with Ni in the redox process of NCA at high potential (Figure 1a,b). The cubic-like NiO structure is also visible in the O K-edge caused by structural change. Despite the presence of Ni, Co and LiF on the LTO surface (Figure 1c), due to the instability of reduced TMs and the LiPF6/binder at the cathode-electrolyte interface, their influence on the electrochemical performances of LTO is limited. Instead, the overall fading of the NCA vs. LTO cell is mainly attributed to the structural degradation of the NCA particles.

Enhanced electrochemical performance of Li4Ti5O12/carbon nanotubes/glucose composite as anode material for lithium ion batteries

Li4Ti5O12 (LTO)/carbon nanotubes (CNTs)/glucose (g) composite is synthesized via solid method followed by sonicating. The influences of carbon nanotubes and glucose additives on the microstructure and electrochemical performances of LTO are investigated. As-prepared LTO composited with 2.5 wt% CNTs and 2 wt% glucose (LTO/2.5CNTs/2 g) exhibits excellent electrochemical performances. On the one hand, LTO/2.5CNTs/2 g composite shows well dispersed between LTO particles and CNTs with width of 200–400 nm. On the other hand, with higher surface areas 45.8839 m2 g−1 and pore volume of 0.2036 ml g−1, the discharge capacity of LTO/2.5CNTs/2 g can reach 251.9 mAh g−1 at 20 mA g−1, while its discharge capacity still reaches 119.3 mAh g−1 at 2 A g−1. Additionally, LTO/2.5CNTs/2 g composite achieves initial discharge capacity of 173.2 mAh g−1 at 1 A g−1, stabilizing at 118.9 mAh g−1 after 1000 cycles. More importantly, its band gap is the least with Li+ diffusion coefficient 1.14 × 10−11 cm2 s−1.

Modelling the rheology and electrochemical performance of Li4Ti5O12 and LiNi1/3Co1/3Mn1/3O2 based suspensions for semi-solid flow batteries

A semi-solid flow battery, consisting in a single channel with millimetric width, was operated in flow conditions using Li4Ti5O12 (LTO) or LiNi1/3Co1/3Mn1/3O2 (LNCM) based suspensions versus Li metal. Cell voltages were measured experimentally for various values of charge/discharge current. A model of the electrochemical cell was developed and validated by comparing calculated results with experimental data. The model consists in solving simultaneously the suspension rheology, potential and current within the cell (secondary distribution) and state of charge evolution between the inlet and outlet. Modelling results indicate low pressure drop (<50 kPa), nearly-homogeneous velocity profile along the channel and potential and current gradients in the cell. Comparison of experimental and calculated results indicate that the model takes into account the influence of applied current density on the cell potential but with significant differences on their absolute value, which are discussed in terms of electrochemical stability for the semi-solid suspensions during cycling. Results detailed in this article can, therefore, be applied to larger electrochemical cells or systems based on alternative chemistries, operated in flow conditions.

Synthesis and characterization of lithium titanate (Li4Ti5O12) nanopowder for battery applications

Nanostructured lithium titanate (Li4Ti5O12) nanopowder was successfully synthesized by simple peroxide route using titanium oxysulphate and lithium hydroxide. The structural properties of the as-prepared and sintered powders were characterized by using powder X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy. Surface morphological property was studied by scanning electron microscope. Compositional analysis was studied using X-ray photo electron spectroscopy. The thermal degradation behavior of the as-synthesized materials was analyzed by thermo gravimetric analysis (TG–DTA). The electrochemical properties of the Li4Ti5O12 nanopowders were examined using galvanostatic charge/discharge test. The effect of sintering temperature on its various physical properties and the electrochemical performances of Li4Ti5O12 was investigated. The storage capacity value obtained for Li4Ti5O12 and Li4Ti5O12/graphite composite anode was 83.52 and 91.33 mAhg−1 in 1 M LiPF6 at 0.1 mA.

Influence of carbon coating and PANI modification on the electrochemical performance of Li4Ti5O12

The Li4Ti5O12/polyaniline and Li4Ti5O12/С/polyaniline composite materials with different lithium titanate/aniline ratio of 8:1, 4:1, 2:1, 1:1, 1:2, and 1:4 were synthesized by in situ polyaniline (PANI) polymerization. The materials were characterized by high-resolution TEM, X-ray powder diffraction, IR spectroscopy, and TGA. It was shown that polyaniline is uniformly distributed over the surface of Li4Ti5O12 or Li4Ti5O12/С composite. For the sample with the minimum polyaniline content (Li4Ti5O12/С/PANI (8:1)), the PANI layer thickness is 2–3 nm and contains polyaniline in the most conductive (emeraldine) form. The lithium titanate modification with polyaniline results in sharp increase in the electronic conductivity of materials from ~ 10−11 Ohm-1 cm−1 for Li4Ti5O12 to 10−4 Ohm-1 cm−1 for Li4Ti5O12/C/PANI. With increasing polyaniline content, the electrochemical capacity decreases for all samples, including carbon-coated and uncoated ones. The highest discharge capacity at current density < 800 mA g−1 is attained for the Li4Ti5O12/С/PANI (8:1) composite.

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.

Electrochemical Performance of Li4Ti5O12 Nanowire/Fe3O4 Nanoparticle Compound as Anode Material of Lithium Ion Batteries

Li4Ti5O12 as one of the commercialized materials, is famous for its excellent reversibility, but also suffered from two drawbacks- low theoretical capacity and difficulty in SOC estimation. In this study, we report a Li4Ti5O12 nanowire/Fe3O4 nanoparticle compound synthesized by hydrothermal method as anode material for lithium ion battery. By in-situ synthesizing Fe3O4 nanoparticles on the surface of Li4Ti5O12 nanowire, particle size of Fe3O4 is remarkably reduced and this resulting in good reversibility of electrode. Moreover, this Li4Ti5O12 nanowire/Fe3O4 nanoparticle compound exhibits much larger capacity than pure-phase Li4Ti5O12. And most importantly, the Li4Ti5O12 nanowire/Fe3O4 nanoparticle compound displays a slope voltage profile, which makes the voltage based SOC estimation much easier than Li4Ti5O12.

Process Design for Size-Controlled Flame Spray Synthesis of Li4Ti5O12 and Electrochemical Performance

Abstract Inexpensive synthesis of electroceramic materials is required for efficient energy storage. Here the design of a scalable process, flame spray pyrolysis (FSP), for synthesis of size-controlled nanomaterials is investigated focusing on understanding the role of air entrainment (AE) during their aerosol synthesis with emphasis on battery materials. The AE into the enclosed FSP reactor is analysed quantitatively by computational fluid dynamics (CFD) and calculated temperatures are verified by Fourier transform infrared spectroscopy (FTIR). Various Li4Ti5O12 (LTO) particle compositions are made and characterized by N2 adsorption, electron microscopy and X-ray diffraction while the electrochemical performance of LTO is tested at various charging rates. Increasing AE decreases recirculation in the enclosing tube leading to lower reactor temperatures and particle concentrations by air dilution as well as shorter and narrower residence time distributions. As a result, particle growth by coagulation - coalescence decreases leading to smaller primary particles that are mostly pure LTO exhibiting high C-rate performance with more than 120 mAh/g galvanostatic specific charge at 40C, outperforming commercial LTO. The effect of AE on FSP-made particle characteristics is demonstrated also in combustion synthesis of LiFePO4 and ZrO2.

Effect of graphene nanosheets on electrochemical performance of Li4Ti5O12 in lithium-ion capacitors

In order to improve the electrochemical performance of lithium titanium oxide, Li4Ti5O12 (LTO), for the use in the lithium-ion capacitors (LICs) application, LTO/graphene composites were synthesized through a solid state reaction. The composite exhibited an interwoven structure with LTO particles dispersed into graphene nanosheets network rather than an agglomerated state pristine LTO particles. It was found that there is an optimum percentage of graphene additives for the formation of pure LTO phase during the solid state synthesis of LTO/graphene composite. The effect of graphene nanosheets addition on electrochemical performance of LTO was investigated by a systemic characterization of galvanostatic cycling in lithium and lithium-ion cell configuration. The optimized composite exhibited a decreased polarization upon cycling and delivered a specific capacity of 173mAhg−1 at 0.1C and a well maintained capacity of 65mAhg−1 even at 20C. The energy density of 14Whkg−1 at a power density of 2700Wkg−1 was exhibited by a LIC full cell with a balanced mass ratio of anode to cathode along with a superior capacitance retention of 97% after 3000 cycles at a current density of 0.4Ag−1. This boost in reversible capacity, rate capability and cycling performance was attributed to a synergistic effect of graphene nanosheets, which provided a short lithium ion diffusion path as well as facile electron conduction channels.

Ionic Conductor of Li2SiO3 as an Effective Dual-Functional Modifier To Optimize the Electrochemical Performance of Li4Ti5O12 for High-Performance Li-Ion Batteries.

Ionic conductor of Li2SiO3 (LSO) was used as an effective modifier to fabricate surface-modified Li4Ti5O12 (LTO) via simply mixing followed by sintering at 750 °C in air. The electrochemical performance of LTO was enhanced by merely adjusting the mass ratio of LTO/LSO, and the LTO/LSO composite with 0.51 wt % LSO exhibited outstanding rate capabilities (achieving reversible capacities of 163.8, 157.6, 153.1, 147.0, and 137.9 mAh g-1 at 100, 200, 400, 800, and 1600 mA g-1, respectively) and remarkable long-term cycling stability (120.2 mAh g-1 after 2700 cycles with a capacity fading rate of only 0.0074% per cycle even at 500 mA g-1). Combining structural characterization with electrochemical analysis, the LSO coating coupled with the slight doping effect adjacent to the LTO surface contributes to the enhancement of both electronic and ionic conductivities of LTO.

Improved electrochemical performance of Li4Ti5O12 by reducing rutile TiO2 phase impurity and particle size

Pure lithium titanate (Li4Ti5O12) powder having particle size of 100 (±38) nm has been prepared by solid-state synthesis method, using planetary ball milling at lower speed of 900 rpm as compared to high energy ball milling (3000 rpm) and characterized by X-ray diffractometer, field emission scanning electron microscopy and thermogravimetric analysis. Electrochemical performance of Li-ion battery cells is determined by charging–discharging and cyclic voltammetry tests. The material has shown very high discharge capacity of 171 and 108 mAhg−1 measured at current rates of 0.1C and 5C, respectively, as compared to 160 and 71 mAhg−1 for impure Li4Ti5O12 material (containing rutile phase of TiO2) having particle size 213 (±45) nm. Capacity retention of pure Li4Ti5O12 was 91% after 100 cycles, whereas the impure Li4Ti5O12 has shown the retention ability of 85%.