This work aimed to prepare the spinel phase Li4Ti5O12 by a combination of the low-temperature precipitation technique and assisted calcination step. X-ray diffraction (XRD) revealed that the intermediated phase was Li2TiO3, and the spinel phase could be evidently formed at 700°C for 12 to 20 hours. The morphology of spinel powder, determined by SEM and TEM, exhibited a good distribution at the submicrometric scale that promoted a fast kinetic of Li migration and an excellent performance at the high-rate cycling test. The stable performances were achieved in the charge-discharge test at different current densities: 80 mA/g (165 mAh/g), 320 mA (160 mAh/g), and 1600 mA (145 mAh/g) upon 100 cycles. Moreover, we observe a capacity retention of 48% (corresponding 80 mA/g) at a high rate of 5000 mAh/g. The cyclic voltammetry measurement displayed a reversible system and revealed the lithium diffusion coefficient of 1.15 × 10−11 cm2/s.
Spinel Li4Ti5O12 has become an attractive anode material for high-power and fast-charging Li-ion battery because of its excellent cycle performance, structural stability, and little change in the unit cell volume during lithium intercalation/deintercalation. The spinel structure of Li4Ti5O12 provides a three-dimensional network for Li migration [
In the literature, many efforts have been aimed to overcome these disadvantages by doping or carbon coating of particles [
Our work aimed to prepare the nanosized spinel Li4Ti5O12 powder from the intermediated cubic phase Li2TiO3 which was obtained from a low-temperature precipitation. The effect of temperature and duration of calcination on the formation of the spinel phase was regarded. The structural and morphological properties were characterized by powder X-ray diffraction, Raman spectroscopy, and scanning/transmission electronic microscopy (SEM/TEM). The high-rate performance through galvanostatic charge-discharge and the diffusion coefficient of lithium ions (
Spinel-type Li4Ti5O12 was prepared via a low-temperature precipitation method combining with the calcining process from 600 to 800°C. Titanium butoxide Ti(OBu)4 with a normal purity of 97% (Sigma Aldrich,
The structure of samples was identified by X-ray diffraction (XRD) in D8-Advance (Bruker) diffractometer using CuK
The electrochemical performance, including rate capability and charge/discharge capacity of spinel Li4Ti5O12, was evaluated at room temperature with the coin-cell type CR-2025 in which a metallic lithium foil was used as the counterelectrode. The composite electrodes were made of the active material (80 wt.%), conducting acetylene black (7.5 wt.%), carbon graphite (7.5 wt.%), and polyvinylidene fluoride (PVdF) binder (5 wt.%) homogeneously dispersed in
A constant current protocol in the range of 20 mA/g to 5000 mA/g was used for formation cycles in a potential range of 1–2.5 V (vs. Li+/Li). The cyclic voltammetry (CV) was performed at different scan rates between the voltage of 10 and 120
Considering the structure of Li4Ti5O12, the previous studies [
XRD patterns of samples at different calcination temperatures.
In order to examine the impact of calcination time, the sample at 700°C was treated at variable scheduling (Figure
XRD patterns of samples at different calcination times at 700°C.
Raman active modes of spinel Li4Ti5O12 involve F2g, Eg, and A1g following the calculation of symmetry group
Figure
Raman spectroscopy of Li4Ti5O12.
SEM images (a) and TEM image (b) of Li4Ti5O12 treated at 700°C for 16 hours.
The electrochemical performance of the spinel nanosized Li4Ti5O12 as anode materials for lithium ion batteries has been investigated. Figure
(a) Typical charge-discharge curves at current density of 20 mA/g and (b) cycling performance of samples Li4Ti5O12 calcinated at 700°C for 12 hours, 16 hours, and 20 hours.
Spinel Li4Ti5O12 is subjected to cycling at different charge-discharge rates such as 80 mA/g, 320 mA/g, and 1600 mA/g to evaluate the capacity-rate relationship (Figure
(a) Typical charge-discharge curves at current density: 80, 320, and 1600 mA/g and (b) cycling performance of Li4Ti5O12.
The rate capability is also important parameter for evaluating an electrode material addressed to the battery as well as supercapacitor application. A constant current discharge test was performed on Li4Ti5O12 electrodes varying the rate from 20 mA/g to 5000 mA/g during discharge in the voltage range of 1.0–2.5 V, with the voltage profiles visible in Figures
(a–c) Charge-discharge profile of Li4Ti5O12 at various current densities from 40 mA/g to 5000 mA/g and (d) electrode polarization and specific capacity as the function of C-rate.
Figure
Cyclic voltammetry analysis has been carried out to further investigate the electrochemical properties of spinel Li4Ti5O12. Figure
(a) CV curves under various scan rates from 10
In summary, spinel Li4Ti5O12 has been successfully prepared through a low temperature precipitation process to obtain a particle-size distribution at the submicrometric scale. The electrochemical measurements show that spinel LTO exhibited the discharge capacity of 178 mAh/g at 0.1°C in the first discharge and favorable cyclic reversibility at different current rates of 20, 80, 320, and 1600 mA/g with a capacity of 167, 165, 160, and 135 mAh/g upon 100 cycles. Furthermore, the spinel samples show an excellent performance at extremely high rate, which is capable of delivering a capacity of 80 mAh/g at current 5000 mA/g.
The data used to support the findings of this study are available from the corresponding author upon request.
The authors declare that they have no conflicts of interest.
This research was funded by the Department of Science and Technology in Ho Chi Minh City (DOST) under contract no. 135/2017/HĐ-SKHCN.