Electrical and electrochemical properties of carbon nanotube-based free standing LTO electrodes for current collector-free Li-ion batteries

The spinel lithium titanate oxide (Li₄Ti₅O₁₂, LTO) has been extensively studied as one of the most promising alternatives to carbon materials in energy conversion and storage devices, due to its high structural and thermal stability, rate capability, and excellent cycling stability. In this study, Li₄Ti₅O₁₂/multi-walled carbon nanotubes (LTO-MWCNTs) free-standing and flexible composite electrodes/buckypapers were prepared via tape casting technique and well compared with commercially available LTO. The structural, morphological, electrical and electrochemical properties of LTO-MWCNTs buckypaper as well as LTO were studied. The electrical conductivity of LTO-based buckypaper was found to be very high i. e, 4.4 × 10² Scm⁻¹ at room temperature. Further, the buckypaper prepared by synthesized LTO showed higher specific capacity (166 mAhg⁻¹) compared to commercially available LTO (137 mAhg⁻¹) at 0.2 C rate. The enhanced electrochemical performance of as-synthesized LTO-based buckypaper is mainly attributed to the higher electronic conductivity and homogeneous distribution of particles with its small size which facilitates large amount of active sites for lithium insertion and also short diffusion paths.     

Pr-modified Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> nanofibers as an anode material for lithium-ion batteries with outstanding cycling performance and rate performance

Pr-doped Li₄Ti₅O₁₂ in the form of Li_4?x/3Ti_5?2x/3Pr_xO₁₂ (x = 0, 0.01, 0.03, 0.05, and 0.07) was synthesized successfully by an electrospinning technique. ICP shows that the doped samples are closed to the targeted samples. XRD analysis demonstrates that traces of Pr³⁺ can enlarge the lattice parameter of Li₄Ti₅O₁₂ from 8.3403 to 8.3765 Å without changing the spinel structure. The increase of lattice parameter is beneficial to the intercalation and de-intercalation of lithium-ion. XPS results identify the existence form of Ti is mainly Ti⁴⁺ and Ti³⁺ in minor quantity in Li_4?x/3Ti_5?2x/3Pr_xO₁₂ (x = 0.05) samples due to the small amount of Pr³⁺. The transition from Ti⁴⁺ to Ti³⁺ is conducive to the electronic conductivity of Li₄Ti₅O₁₂. FESEM images show that all the nanofibers are well crystallized with a diameter of about 200 nm and distributed uniformly. The results of electrochemical measurement reveal that the 1D Li_4?x/3Ti_5?2x/3Pr_xO₁₂ (x = 0.05) nanofibers display enhanced high-rate capability and cycling stability compared with that of undoped nanofibers. The high-rate discharge capacity of the Li_4?x/3Ti_5?2x/3Pr_xO₁₂ (x = 0.05) samples is excellent (101.6 mAh g^?1 at 50 °C), which is about 58.48 % of the discharge capacity at 0.2 °C and 4.3 times than that of the bare Li₄Ti₅O₁₂ (23.5 mA g^?1). Even at 10 °C (1750 mA g^?1), the specific discharge capacity is still 112.8 mAh g^?1 after 1000 cycles (87.9 % of the initial discharge capacity). The results of cyclic voltammograms (CV) and electrochemical impedance spectroscopy (EIS) illustrate that the Pr-doped Li₄Ti₅O₁₂ electrodes possess better dynamic performance than the pure Li₄Ti₅O₁₂, further confirming the excellent electrochemical properties above.     

Electrospinning preparation of one-dimensional Co<Superscript>2+</Superscript>-doped Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> nanofibers for high-performance lithium ion battery

One-dimensional Co²⁺-doped Li₄Ti₅O₁₂ nanofibers with a diameter of approximately 500 nm have been synthesized via a one-step controllable electrospinning method. The Co²⁺-doped Li₄Ti₅O₁₂ nanofibers were systematically characterized by XRD, ICP, TEM, SEM, BET, EDS mapping, and XPS. Based on the cubic spinel structure and one-dimensional effect of Li₄Ti₅O₁₂, Co²⁺-doped Li₄Ti₅O₁₂ nanofibers exhibit the enlarged lattice volume, reduced particle size and enhanced electrical conductivity. More importantly, Co²⁺-doped Li₄Ti₅O₁₂ nanofibers as a lithium ion battery anode electrode performs superior electrochemical performance than undoped Li₄Ti₅O₁₂ electrode in terms of electrochemical measurements. Particularly, the reversible capacity of Co²⁺-doped Li₄Ti₅O₁₂ electrode reaches up to 140.1 mAh g^?1 and still maintains 136.5 mAh g^?1 after 200 cycles at a current rate of 5 C. Therefore, one-dimensional Co²⁺-doped Li₄Ti₅O₁₂ nanofiber electrodes, showing high reversible capacity and remarkable recycling property, could be a potential candidate as an anode material.     

Enhanced electrochemical performance of Cu<Subscript>2</Subscript>O-modified Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> anode material for lithium-ion batteries

Li₄Ti₅O₁₂/Cu₂O composite was prepared by ball milling Li₄Ti₅O₁₂ and Cu₂O with further heat treatment. The structure and electrochemical performance of the composite were investigated via X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge tests. Li₄Ti₅O₁₂/Cu₂O composite exhibited much better rate capability and capacity performance than pristine Li₄Ti₅O₁₂. The discharge capacity of the composite at 2 C rate reached up to 122.4 mAh g^?1 after 300 cycles with capacity retention of 91.3 %, which was significantly higher than that of the pristine Li₄Ti₅O₁₂ (89.6 mAh g^?1). The improvement can be ascribed to the Cu₂O modification. In addition, Cu₂O modification plays an important role in reducing the total resistance of the cell, which has been demonstrated by the electrochemical impedance spectroscopy analysis.     

Preparation and electrochemical properties of Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript>/Ti<Subscript>4</Subscript>O<Subscript>7</Subscript> composite for lithium-ion batteries

In order to improve the rate capability of Li₄Ti₅O₁₂, Ti₄O₇ powder was successfully fabricated by improved hydrogen reduction method, then a dual-phase composite Li₄Ti₅O₁₂/Ti₄O₇ has been synthesized as anode material for lithium-ion batteries. It is found that the Li₄Ti₅O₁₂/Ti₄O₇ composite shows higher reversible capacity and better rate capability compared to Li₄Ti₅O₁₂. According to the charge-discharge tests, the Li₄Ti₅O₁₂/Ti₄O₇ composite exhibits excellent rate capability of 172.3 mAh g^?1 at 0.2 C, which is close to the theoretical value of the spinel Li₄Ti₅O₁₂. More impressively, the reversible capacity of Li₄Ti₅O₁₂/Ti₄O₇ composite is 103.1 mAh g^?1 at the current density of 20 C after 100th cycles, and it maintains 84.8% of the initial discharge capacity, whereas that of the bare spinel Li₄Ti₅O₁₂ is only 22.3 mAh g^?1 with a capacity retention of 31.1%. The results indicate that Li₄Ti₅O₁₂/Ti₄O₇ composite could be a promising anode material with relative high capacity and good rate capability for lithium-ion batteries.     

Nano Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> as sulfur host for high-performance Li-S battery

S/Li₄Ti₅O₁₂ cathode with high lithium ionic conductivity was prepared for Li-S battery. Herein, nano Li₄Ti₅O₁₂ is used as sulfur host and fast Li⁺ conductor, which can adsorb effectively polysulfides and improve remarkably Li⁺ diffusion coefficient in sulfur cathode. At 0.5 C, S/Li₄Ti₅O₁₂ cathode has a stable discharge capacity of 616 mAh g^?1 at the 700th cycle and a capacity loss per cycle of 0.0196% from the second to the 700th cycle, but the corresponding values of S/C cathode are 437 mAh g^?1 and 0.0598%. Even at 2 C, the capacity loss per cycle of S/Li₄Ti₅O₁₂ cathode is only 0.0273% from the second to the 700th cycle. The results indicate that Li₄Ti₅O₁₂ as the sulfur host plays a key role on the high performance of Li-S battery due to reducing the shuttle effect and enhancing lithium ionic conductivity.     

Influence of post-calcination treatment on the spinel lithium titanium oxide anode material for lithium ion batteries

The influence of post-calcination treatment on spinel Li₄Ti₅O₁₂ anode material is extensively studied combining with a ball-milling-assisted rheological phase reaction method. The post-calcinated Li₄Ti₅O₁₂ shows a well distribution with expanded gaps between particles, which are beneficial for lithium ion mobility. Electrochemical results exhibit that the post-calcinated Li₄Ti₅O₁₂ delivers an improved specific capacity and rate capability. A high discharge capacity of 172.9 mAh g^?1 and a reversible charge capacity of 171.1 mAh g^?1 can be achieved at 1 C rate, which are very close to its theoretical capacity (175 mAh g^?1). Even at the rate of 20 C, the post-calcinated Li₄Ti₅O₁₂ still delivers a quite high charge capacity of 124.5 mAh g^?1 after 50 cycles, which is much improved over that (43.9 mAh g^?1) of the pure Li₄Ti₅O₁₂ without post-calcination treatment. This excellent electrochemical performance should be ascribed to the post-calcination process, which can greatly improve the lithium ion diffusion coefficient and further enhance the electrochemical kinetics significantly.     

Influence of coated MnO2 content on the electrochemical performance of Li1.2Ni0.2Mn0.6O2 cathodes

Layered cathode material Li_1.2Ni_0.2Mn_0.6O₂ has been synthesized using a coprecipitation method and coated by MnO₂ with varying amounts (1, 3, 5, and 9 wt%). The physical properties and electrochemical performances of the materials are characterized by XRD, SEM, charge/discharge tests, cycle life, and rate capability tests. XRD patterns show that the pristine and coated Li_1.2Ni_0.2Mn_0.6O₂ powders exhibit layered structure. The discharge capacities and coulombic efficiencies of Li_1.2Ni_0.2Mn_0.6O₂ in the first cycle have been improved and increase with the increasing content of coated MnO₂. The 9 wt% MnO₂-coated Li_1.2Ni_0.2Mn_0.6O₂ delivers 287 mAhg^?1 for the first discharge capacity and 86.7 % for the first coulombic efficiency compared with 228 mAhg^?1 and 65.9 % for pristine Li_1.2Ni_0.2Mn_0.6O₂. However, the 5 wt% MnO₂-coated Li_1.2Ni_0.2Mn_0.6O₂ shows the best capacity retention (99.9 % for 50 cycles) and rate capability (88.6 mAhg^?1 at 10 C), while the pristine Li_1.2Ni_0.2Mn_0.6O₂ only shows 91.5 % for 50 cycles and 25.3 mAhg^?1 at 10 C. The charge/discharge curves and differential capacity vs. voltage (dQ/dV) curves show that the coated MnO₂ reacts with Li⁺ during the charge and discharge process, which is responsible for higher discharge capacity after coating. Electrochemical impedance spectroscopy results show that the R _ct of Li_1.2Ni_0.2Mn_0.6O₂ electrode decreases after coating, which is responsible for superior rate capability.     

Preparation of carbon encapsulated Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> anode material for lithium ion battery through pre-coating method

Carbon encapsulated Li₄Ti₅O₁₂ (C/Li₄Ti₅O₁₂) anode material for lithium ion battery was prepared by using the pre-coat method of two steps, and the TiO₂ was pre coated before the reaction with Li₂CO₃. The structure and morphology of the resultant C/Li₄Ti₅O₁₂ materials were characterized by X-ray diffraction (XRD) and scanning microscopy (SEM). Electrochemical tests showed that at 0.1 C, the initial discharge capacity was 169.9 mAh g^?1, and the discharge capacity was 80 mAh g^?1 at 5 C. After 100 cycles at 2 C, the discharge specific capacity was 108.5 mAh g^?1. Compare with one step coating method, results showed the C/Li₄Ti₅O₁₂ prepared by pre-coat method can reduce the particle’s size and effectively improve the electrochemical performance.     

Synthesis and characterization of Li4Ti5O12/graphene composite as anode material with enhanced electrochemical performance

The use of graphene as a conductive additive to enhance the rate capability and cycle stability of Li₄Ti₅O₁₂ electrode material has been demonstrated. Li₄Ti₅O₁₂ and its composite with graphene (1.86 wt%) are prepared by ball milling and simple chemical method, respectively. Among the as-synthesized composites, Li₄Ti₅O₁₂ particles uniformly clung to the graphene sheets. When used as an electrode material for lithium ion battery, the composite presents excellent rate performance and high cyclic stability. It is found that the composite displayed high-rate capacity of 118.7 mAh?g^?1 at 20 C. Furthermore, the composite exhibits good cycle stability, retaining over 96 % of its initial capacity after 50 cycles at 10 C. The excellent electrochemical performance is attributed to a decrease in the charge-transfer resistance.     

Effects of dopant on the electrochemical properties of Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> anode materials

The effects of dopant on the electrochemical properties of spinel-type Li_3.97M_0.1Ti_4.94O₁₂ (M = Mn, Ni, Co) and Li_(4-x/3)Cr_xTi_(5-2x/3)O₁₂(x = 0.1, 0.3, 0.6, 0.9, 1.5) were systematically investigated. Charge-discharge cycling were performed at a constant current density of 0.5 mA/cm² between the cut-off voltages of 3.0 and 1.0 V, the experimental results showed that Cr³⁺ dopant improved the reversible capacity and cycling stability over the pristine Li₄Ti₅O₁₂. The substitution of the Mn³⁺ and Ni³⁺ slightly decreased the capacity of the Li₄Ti₅O₁₂. Dopants such as Co³⁺ to some extent worsened the electrochemical performance of the Li₄Ti₅O₁₂.     

Improvement electrochemical performance of Li1.5Ni0.25Mn0.75O2.5 with Li4Ti5O12 coating

Layered cathode Li_1.5Ni_0.25Mn_0.75O_2.5 has been synthesized and coated by Li₄Ti₅O₁₂. The pristine and coated Li_1.5Ni_0.25Mn_0.75O_2.5 powders are characterized by X-ray diffraction (XRD), indicating the materials remained the layered structure before and after coating. The coated Li₄Ti₅O₁₂ has been detected by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (DEX). The electrochemical performance, especially rate performance of Li_1.5Ni_0.25Mn_0.75O_2.5 electrode, is improved effectively after Li₄Ti₅O₁₂ coating. The first discharge capacity, coulombic efficiency, and capacity retention of Li₄Ti₅O₁₂-coated Li_1.5Ni_0.25Mn_0.75O_2.5 electrode are 244 mA h g^?1, 81.5 %, and 98.3 % after 50 cycles, respectively. The Li₄Ti₅O₁₂-coated Li_1.5Ni_0.25Mn_0.75O_2.5 electrode exhibits 108 mA h g^?1 at 10 °C rate. Electrochemical impedance spectroscopy (EIS) results show that the charge transfer resistance (R _ct) of Li_1.5Ni_0.25Mn_0.75O_2.5 electrode decreases after coating, which is due to the existence of Li₄Ti₅O₁₂ with high lithium ion diffusion coefficient and suppression of the solid electrolyte interfacial (SEI) layer development and is responsible for the excellent rate capability and cyclic performance.     

Evolution of crystal structure and electrochemical performance of layered Li<Subscript>1.20</Subscript>Ti<Subscript>0.44</Subscript>Cr<Subscript>0.36</Subscript>O<Subscript>2</Subscript>/C cathode materials with cycling

Carbon-coated layered Li_1.20Ti_0.44Cr_0.36O₂/C and pristine Li_1.20Ti_0.44Cr_0.36O₂ cathode materials have been synthesized through a sol–gel method followed by high-temperature calcination. Their electrochemical performances have been evaluated, which indicate that the Li_1.20Ti_0.44Cr_0.36O₂/C exhibits much higher cyclic stability and capacity than the pristine one. The initial delithiation capacity of the Li_1.20Ti_0.44Cr_0.36O₂/C can reach 217.1 mAh g^?1. The reversible capacity retention is 94 % after 100 cycles at current density of 23 mA g^?1. Ex situ X-ray diffraction and electrochemistry impedance spectroscopy coupled with impedance fitting have been employed to reveal evolution of the crystal structure and the electrochemical kinetics of the Li_1.20Ti_0.44Cr_0.36O₂/C with delithiation/lithiation cycling. The results indicate that the cation layers of the Li_1.20Ti_0.44Cr_0.36O₂/C experience order to disorder transition. The abrupt delithiation capacity fading and potential drop after the initial cycle are resulted from the order to disorder transition accompanying with steep increase of the charge transfer resistance and decrease of the exchange current density and the Li-ion diffusion coefficient simultaneously.     

Enhanced high-rate performance of sub-micro Li4Ti4.95Zn0.05O12 as anode material for lithium-ion batteries

Zn-doped Li₄Ti₅O₁₂ was prepared by a ball milling-assisted solid-state method, and the characters were determined by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, cyclic voltammetry, and galvanostatic charge–discharge testing. The results show that Li₄Ti_5?x Zn _x O₁₂ (x?=?0, 0.05) exhibits the pure phase structure, and Zn doping does not change the electrochemical reaction process and basic spinel structure of Li₄Ti₅O₁₂. The particle size of both samples is about 300–500 nm. The prepared Li₄Ti_4.95Zn_0.05O₁₂ presents an excellent rate capability and capacity retention. At the charge–discharge rate of 1C, the initial discharge capacity of Li₄Ti_4.95Zn_0.05O₁₂ is 268 mAh g^?1. After 90 cycles at 5C, the discharge capacity of Li₄Ti_4.95Zn_0.05O₁₂ is obviously higher than that of Li₄Ti₅O₁₂. The excellent electrochemical performance of the Li₄Ti_4.95Zn_0.05O₁₂ electrode could be attributed to the improvement of reversibility by doping zinc and the sub-micro particle size.     

Synthesis and electrochemical performances of Li4Ti4.95Al0.05O12/C as anode material for lithium-ion batteries

Spinel compounds Li₄Ti_5−xAl_xO₁₂/C (x=0, 0.05) were synthesized via solid state reaction in an Ar atmosphere, and the electrochemical properties were investigated by means of electronic conductivity, cyclic voltammetry, and charge-discharge tests at different discharge voltage ranges (0-2.5 V and 1-2.5 V). The results indicated that Al³⁺ doping of the compound did not affect the spinel structure but considerably improved the initial capacity and cycling performance, implying the spinel structure of Li₄Ti₅O₁₂ was more stable when Ti⁴⁺ was substituted by Al³⁺, and Al³⁺ doping was beneficial to the reversible intercalation and deintercalation of Li⁺. Al³⁺ doping improved the reversible capacity and cycling performance effectively especially when it was discharged to 0 V.     

Preparation and characteristics of Li4Ti5O12 with various dopants as anode electrode for hybrid supercapacitor

Spinel-Li₄Ti₅O₁₂ is successfully synthesized by a solid phase synthesis. The Li₄Ti₅O₁₂ powders with various dopants (Al³⁺, Cr³⁺, Mg²⁺) synthesized at 800 °C are in accordance with the Li₄Ti₅O₁₂ cubic spinel phase structure. The dopants are inserted into the lattice structure of Li₄Ti₅O₁₂ without causing any changes in structural characteristics. In order to study the effect on various dopants, the hybrid supercapacitor is prepared by using un-doped Li₄Ti₅O₁₂ and doped Li₄Ti₅O₁₂ in this work. The electrochemical performance of the hybrid supercapacitor is characterized by impedance spectroscopy and cycle performance. The results show Cr³⁺ and Mg²⁺ dopants enhance the conductivity of Li₄Ti₅O₁₂. Also, Al³⁺ substitution improves the reversible capacity and cycling stability of Li₄Ti₅O₁₂. It is found that effect of dopant on the electrochemical performance of Li₄Ti₅O₁₂ as electrode material for hybrid supercapacitor where the EDLC and the Li ion secondary battery coexist in one cell system.     

Li4Ti5O12/Ag composite as electrode materials for lithium-ion battery

The Li₄Ti₅O₁₂/Ag composites were prepared by thermal decomposition of AgNO₃ added to Li₄Ti₅O₁₂ powders. The influence of the Ag contents and the mixing media on the particle size, morphology and electrochemical performance of Li₄Ti₅O₁₂/Ag composites were investigated. The highest discharge capacity of the Li₄Ti₅O₁₂/Ag composite reached at the 5 wt.% of Ag content. Compared with alcohol medium, distilled water as mixing medium presented the Li₄Ti₅O₁₂/Ag composite with higher specific capacity and better cycling performance, leading to a reversible capacity after 50 cycles of 184.2 mAh/g with a capacity degradation of 3.31% compared to the second cycle at 2 C rate.     

Preparation and characterization of spherical La-doped Li4Ti5O12 anode material for lithium ion batteries

The lithium secondary batteries with high power density need the electrode materials with both high specific capacity and high tap density. An “outer gel” method by TiCl₄ as the raw material has been developed to prepare spherical precursor. High tap density spherical Li₄Ti₅O₁₂ is synthesized by sintering the mixture of precursor and Li₂CO₃. La-doped Li₄Ti₅O₁₂ is also prepared by this method. X-ray diffraction, scanning electron microscopy, energy-dispersive spectrometry, tap density testing, and the determination of the electrochemical properties show that the Li₄Ti₅O₁₂ powders prepared by this method are spherical and exhibits high tap density. La³⁺ dopant improved the electrochemical performance over the pristine Li₄Ti₅O₁₂. It is tested that the tap density of the pristine and La³⁺-doped products is as high as 1.80 and 1.78 g•cm⁻³, respectively. Between 1.0 and 3.0 V versus Li, the initial discharge capacity of the La³⁺ dopant is as high as 161.5 mAh•g⁻¹ at 0.1C rate. After 50 cycles, the reversible capacity is still 135.4 mAh•g⁻¹.     

Solid-state synthesis of graphite carbon-coated Li4Ti5O12 anode for lithium ion batteries

Graphites are widely used for their high electrical conductivity and good thermal and chemical stability. In this work, graphitic carbon-coated lithium titanium (Li₄Ti₅O₁₂/GC) was successfully synthesized by a simple one-step solid-state reaction process with the assistance of sucrose without elevating sintering temperature. The lattice fringe of 0.208 nm clearly seen from the high-resolution transmission electron microscopy (HRTEM) images was assigned to graphite (010). The average grain size of the as-prepared Li₄Ti₅O₁₂/GC was about 100–200 nm, 1 order smaller than that of pure Li₄Ti₅O₁₂ prepared similarly. The rate performance and cycle ability were significantly improved by the hybrid conducting network formed by graphitic carbon on the grains and amorphous carbon between them. The specific capacity retention rate was 66.7 % when discharged at a rate of 12C compared with the capacity obtained at 0.5C. After 300 cycles, the capacity retention was more than 90 % at a high rate of 15C.     

Integrated investigation of the Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> phase stability

The Li₄Ti₅O₁₂ is applied in lithium ion batteries as anode material, which can be synthesized by various synthesis techniques. In this study, the molten salt synthesis technique at low temperatures, i.e. 350 °C, was applied to synthesize Li₄Ti₅O₁₂. Surprisingly, the Li₄Ti₅O₁₂ was not formed according to XRD analysis, which raised question about the stability range of Li₄Ti₅O₁₂. To investigate the stability of Li₄Ti₅O₁₂ at low temperatures, the high-temperature calcined Li₄Ti₅O₁₂ powder was equilibrated in the LiCl-KCl eutectic salt at 350 °C. The result of experiment revealed that the Li₄Ti₅O₁₂ is not decomposed. Results of ab initio calculations also indicated that the Li₄Ti₅O₁₂ phase is a stable phase at 0 K. The products of molten salt synthesis technique were then annealed at 900 °C, which resulted in the Li₄Ti₅O₁₂ formation. It was concluded that the Li₄Ti₅O₁₂ is a stable phase at low temperatures and the reasons for not forming the Li₄Ti₅O₁₂ by molten salt technique at low temperature are possibly related to activation energy and kinetic barriers. The Li₄Ti₅O₁₂ formation energy is also very small, due to the results of ab initio calculations.