Papers by Keyword: Li₄Ti₅O₁₂

Abstract: We have presented the results of detailed studies of oxygen vacancy and niobium (Nb) substituted spinel Li4Ti5O12 (LTO) materials using first-principles method within the framework of the density functional theory (DFT). We have shown that the ground state of oxygen vacancy and Nb substituted LTO is paramagnetic (PM), and the Nb substitution is most stable on the 16d sites of both the Li and Ti ions. We have indicated that the Nb substitution in the 16d site of Li ion become the n-type metallic material. But the oxygen vacancy containing NbT i substituted LTO is changed from the p-type to the n-type, as increased a concentration of Nb ions.

Abstract: The Li₄Ti₅O₁₂/Co₃O₄ composites were prepared by hydrothermal reaction method with different Co₃O₄ mass content (3%, 7%, 11%, and 15%). The Li₄Ti₅O₁₂ nanoparticles were set in-situ on the Co₃O₄ sheet. Co ion was doped into the Li₄Ti₅O₁₂ lattice. The first cycle specific capacity firstly increased and then decreased with Co₃O₄ content increasing, which the discharge capacity reached the peaking value that the first capacity was 1111 mAh/g and the specific discharge capacity retained 240 mAh/g after 200 cycles. After 200 cycles of charge and discharge, the retention of the capacity was 96.4% at 0.1 A/g, and the retention of the capacity was 98.4% at 0.5 A/g.

Abstract: We investigated the electrochemical behavior and properties of lithium titanate oxide as the negative electrode for calcium ion batteries during charge/discharge tests in tetrahydrofuran (THF)-based electrolyte. The reversible charge and discharge capacities of ~150 and ~145 mAh g^–1 were observed, respectively, in THF-based electrolyte. They are larger than those obtained in propylene carbonate-based electrolyte. Moreover, interesting charge/discharge curves were observed, which might be attributed to structural changes during the insertion/extraction of calcium ions. These results were confirmed by the charge/discharge curves and scanning electron microscopy images.

Abstract: The electrochemical behaviors of a spinel lithium titanate oxide (Li₄Ti₅O₁₂, LTO) electrode during as a novel electrode for calcium ion batteries were investigated during the charging and discharging to understand its electrochemical properties. The electrochemical performance of the LTO electrode was improved by the addition of dimethyl carbonate to the PC-based electrolyte. The initial charge and discharge capacities were ~262 and ~85 mAh g^–1, respectively. The results of the X-ray diffraction analysis showed that the lattice constant of LTO increased after charging, indicating that calcium ions were inserted into Li₄Ti₅O₁₂ during the charging.

Abstract: Graphitized-Carbon coated Li₄Ti₅O₁₂/C (Li₄Ti₅O₁₂/GC) composites were prepared from Li₂CO₃, TiO₂ and aromatic resorcinol via a facile rheological phase method. The microstructure and morphology of the samples were determined by XRD and SEM. The electrochemical performances of the samples were characterized by galvanostatic charge-discharge test and electrochemical impedance spectroscopy (EIS). The results reveal that the coating of graphitized carbon could effectively enhance the charge/transfer kinetics of the Li₄Ti₅O₁₂ electrode. The Li₄Ti₅O₁₂/GC could deliver a discharge specific capacity of 166 mAh/g at 0.2 C, 148 mAh/g at 1.0 C, 142 mAh/g at 3.0 C, 138 mAh/g at 5.0 C and 127 mAh/g at 10.0 C, respectively, and it still could remain at 132 mAh/g after cycled at 5.0 C for 100 cycles. The excellent rate capability of the Li₄Ti₅O₁₂/C makes it a promising anode material for high rate lithium ion batteries.

Abstract: Spinel Li_4-xK_xTi₅O₁₂ (x=0, 0.03) were successfully synthesized by a traditional solid-state method and systematically investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and the charge-discharge test, respectively. The results demonstrated that Li_3.97K_0.03Ti₅O₁₂ exhibited much better rate performance in comparsion with Li₄Ti₅O₁₂. At 0.2 C and 10 C, it delivered a discharge capacity of 173 mAh g^-1 and 124 mAh g^-1 respectively, and after 100 cycles at 10 C, 96.1% of its initial capacity was retained.

Abstract: Li₄Ti₅O₁₂ powders were synthesized via the solid state reaction of Li₂CO₃ and spherical composite powders of carbon and TiO₂ (denoted by C/TiO₂) with different microstructures. These C/TiO₂ powders were synthesized by spray pyrolysis using various organic acid aqueous solutions. The particle characteristics of the resulting carbon composite Li₄Ti₅O₁₂ (denoted by C/Li₄Ti₅O₁₂) powders were determined using SEM, XRD, and DTA-TG. DTA-TG showed that the carbon content of all Li₄Ti₅O₁₂ powders. was around 3 wt%. XRD revealed that the spinel structure (Fd3m) was obtained by heating at 750 °C under N₂ atmosphere. The initial rechargeable capacity of the C/Li₄Ti₅O₁₂ powders formed using citric acid was approximately 170 mAh/g at 1 C. The rechargeable capacity of the C/Li₄Ti₅O₁₂ powders decreased with an increase in the rechargeable rate. The anodes maintained over 90% of their initial discharge capacity after 200 cycles at 1 C. The C/Li₄Ti₅O₁₂ powders also demonstrated high cycle stability at 50 °C. It was found that rechargeable capacity was influenced by the particles microstructure, but cycle stability did not depend on the microstructure.

Abstract: Lithium titanate (Li4Ti5O12) was synthesized by solid-state method with anatase titanium dioxide and lithium carbonate(Li2CO3) as raw materials at 800°C,900°C and 1000°C for 12h, respectively. The prepared powder was characterized by XRD, SEM and constant current charge/discharge test. The results showed that the calcination temperature effected on the properties of Li4Ti5O12 powder, the crystallinity and particle size of powder were changed with the calcination temperature. Li4Ti5O12 had good performance of 1ithium insertion/extraction, stable charge/discharge platform, excellent multipule cycles of high capacity at 900°C.

Abstract: Li₄Ti₅O₁₂ nanoparticles were synthesized through hydrothermal method. The structure and morphology characteristics of the composite were investigated by XRD, SEM. Meanwhile, electrochemical properties were analyzed through charging-discharging test. The prepared Li₄Ti₅O₁₂ nanoparticles had good rate performance and cycling performance. It exhibited discharging capacity of 136.0 mAh/g at a high rate of 10 C. It also had good performance when it charging at low rate and discharging at high rate.

Abstract: Spinel Li4Ti5O12 was prepared by a solution method. The structure and morphology of the samples were characterized by X-ray diffraction, scanning electron microscopy. The electrochemical performance was investigated by initial charge-discharge at different rate. The results revealed that the crystallinity of Li₄Ti₅O₁₂ was well, the Li₄Ti₅O₁₂ prepared by solution method had a relatively smaller particle size and homogeneous morphology. It delivered a discharge capacity 178.59 mAh•g⁻¹ for the Li₄Ti₅O₁₂ at the 0.2C discharge to 1V. The reversible capacity 141.98mAh•g⁻¹ could be achieved at the 5C . Li₄Ti₅O₁₂ prepared by a solution method showed good rate performance.