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Title: Dual Phase Li 4Ti 5O 12–TiO 2 Nanowire Arrays As Integrated Anodes For High-rate Lithium-ion Batteries

Abstract

Lithium titanate (Li 4Ti 5O 12) is well known as a zero strain material inherently, which provides excellent long cycle stability as a negative electrode for lithium ion batteries. However, the low specific capacity (175 mA h g -1) limits it to power batteries although the low electrical conductivity is another intrinsic issue need to be solved. In this work, we developed a facile hydrothermal and ion-exchange route to synthesize the self-supported dual-phase Li 4Ti 5O 12–TiO 2 nanowire arrays to further improve its capacity as well as rate capability. The ratio of Li 4Ti 5O 12 to TiO 2 in the dual phase Li 4Ti 5O 12–TiO 2 nanowire is around 2:1. The introduction of TiO 2 into Li 4Ti 5O 12 increases the specific capacity. More importantly, by interface design, it creates a dual-phase nanostructure with high grain boundary density that facilitates both electron and Li ion transport. Compared with phase-pure nanowire Li 4Ti 5O 12 and TiO 2 nanaowire arrays, the dual-phase nanowire electrode yielded superior rate capability (135.5 at 5 C, 129.4 at 10 C, 120.2 at 20 C and 115.5 mA h g -1 at 30 C). In-situ transmission electron microscope clearly shows the nearmore » zero deformation of the dual phase structure, which explains its excellent cycle stability.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1170470
Report Number(s):
PNNL-SA-105729
48170
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nano Energy, 9:383-391
Country of Publication:
United States
Language:
English
Subject:
Environmental Molecular Sciences Laboratory

Citation Formats

Liao, Jin, Chabot, Victor, Gu, Meng, Wang, Chong M., Xiao, Xingcheng, and Chen, Zhongwei. Dual Phase Li4Ti5O12–TiO2 Nanowire Arrays As Integrated Anodes For High-rate Lithium-ion Batteries. United States: N. p., 2014. Web. doi:10.1016/j.nanoen.2014.06.032.
Liao, Jin, Chabot, Victor, Gu, Meng, Wang, Chong M., Xiao, Xingcheng, & Chen, Zhongwei. Dual Phase Li4Ti5O12–TiO2 Nanowire Arrays As Integrated Anodes For High-rate Lithium-ion Batteries. United States. doi:10.1016/j.nanoen.2014.06.032.
Liao, Jin, Chabot, Victor, Gu, Meng, Wang, Chong M., Xiao, Xingcheng, and Chen, Zhongwei. Tue . "Dual Phase Li4Ti5O12–TiO2 Nanowire Arrays As Integrated Anodes For High-rate Lithium-ion Batteries". United States. doi:10.1016/j.nanoen.2014.06.032.
@article{osti_1170470,
title = {Dual Phase Li4Ti5O12–TiO2 Nanowire Arrays As Integrated Anodes For High-rate Lithium-ion Batteries},
author = {Liao, Jin and Chabot, Victor and Gu, Meng and Wang, Chong M. and Xiao, Xingcheng and Chen, Zhongwei},
abstractNote = {Lithium titanate (Li4Ti5O12) is well known as a zero strain material inherently, which provides excellent long cycle stability as a negative electrode for lithium ion batteries. However, the low specific capacity (175 mA h g-1) limits it to power batteries although the low electrical conductivity is another intrinsic issue need to be solved. In this work, we developed a facile hydrothermal and ion-exchange route to synthesize the self-supported dual-phase Li4Ti5O12–TiO2 nanowire arrays to further improve its capacity as well as rate capability. The ratio of Li4Ti5O12 to TiO2 in the dual phase Li4Ti5O12–TiO2 nanowire is around 2:1. The introduction of TiO2 into Li4Ti5O12 increases the specific capacity. More importantly, by interface design, it creates a dual-phase nanostructure with high grain boundary density that facilitates both electron and Li ion transport. Compared with phase-pure nanowire Li4Ti5O12 and TiO2 nanaowire arrays, the dual-phase nanowire electrode yielded superior rate capability (135.5 at 5 C, 129.4 at 10 C, 120.2 at 20 C and 115.5 mA h g-1 at 30 C). In-situ transmission electron microscope clearly shows the near zero deformation of the dual phase structure, which explains its excellent cycle stability.},
doi = {10.1016/j.nanoen.2014.06.032},
journal = {Nano Energy, 9:383-391},
number = ,
volume = ,
place = {United States},
year = {Tue Aug 19 00:00:00 EDT 2014},
month = {Tue Aug 19 00:00:00 EDT 2014}
}
  • Highlights: • Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposites with high grain boundary density were synthesized. • {sup 7}Li NMR and impedance spectroscopy shows high Li-ion mobility in nanocomposites. • The shape of charge/discharge curves changes for nanocomposites. • Influence of particle size on cycling performance of lithium titanates was shown. • Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposite exhibits good cycling performance and rate capability. - Abstract: Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposites are synthesized by a sol-gel method. The size of Li{sub 4}Ti{sub 5}O{sub 12} and TiO{sub 2} particles is of 4–5 and 7–10 nm, respectively. The obtained materials aremore » characterized by XRD, SEM, HRTEM and BET. Ion mobility of the composites and their performance as anode materials for lithium-ion batteries are studied. According to the conductivity and {sup 7}Li NMR data, Li{sup +} mobility is much higher in the Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposites as compared with that in pure Li{sub 4}Ti{sub 5}O{sub 12}. For Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposites, marked changes in the charge–discharge curves are observed; charge–discharge rate and effective capacity at a high cycling rate are shown to increase. During the first cycle, charge capacity of these materials surpasses the theoretical capacity of Li{sub 4}Ti{sub 5}O{sub 12}. However, this parameter decreases sharply with cycling, whereas the discharge capacity remains almost unchanged. This phenomenon is attributed to the solid electrolyte interphase formation due to a partial electrolyte reduction on the Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} composite surface.« less
  • Doped motifs offer an intriguing structural pathway toward improving conductivity for battery applications. Specifically, Ca-doped, three-dimensional “flower-like” Li 4–xCa xTi 5O 12 (“x” = 0, 0.1, 0.15, and 0.2) micrometer-scale spheres have been successfully prepared for the first time using a simple and reproducible hydrothermal reaction followed by a short calcination process. The products were experimentally characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) mapping, inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge testing. Calcium dopantmore » ions were shown to be uniformly distributed within the LTO structure without altering the underlying “flower-like” morphology. The largest lattice expansion and the highest Ti 3+ ratios were noted with XRD and XPS, respectively, whereas increased charge transfer conductivity and decreased Li +-ion diffusion coefficients were displayed in EIS for the Li 4–xCa xTi 5O 12 (“x” = 0.2) sample. The “x” = 0.2 sample yielded a higher rate capability, an excellent reversibility, and a superior cycling stability, delivering 151 and 143 mAh/g under discharge rates of 20C and 40C at cycles 60 and 70, respectively. In addition, a high cycling stability was demonstrated with a capacity retention of 92% after 300 cycles at a very high discharge rate of 20C. In addition, first-principles calculations based on density functional theory (DFT) were conducted with the goal of further elucidating and understanding the nature of the doping mechanism in this study. The DFT calculations not only determined the structure of the Ca-doped Li 4Ti 5O 12, which was found to be in accordance with the experimentally measured XPD pattern, but also yielded valuable insights into the doping-induced effect on both the atomic and electronic structures of Li 4Ti 5O 12.« less
  • Monodispersed Li 4Ti 5O 12 (LTO) nanoparticles with controlled microstructure were successfully synthesized by a combination of hydrolysis and hydrothermal method followed by a post-annealing process. The scanning electron microscopy images showed that particles with a size of 30-40 nm were precisely controlled throughout the synthesis process. The electrochemical tests of the as-prepared LTO electrodes in a half-cell proved its high rate performance and outstanding cyclability which benefits from the preserved well-controlled nanoparticle size and morphology. LTO electrodes were also tested in a full cell configuration in pairing with LiFePO 4 cathodes, which demonstrated a capacity of 147.3 mAh gmore » -1. In addition, we have also demonstrated that LTO materials prepared using lithium salts separated from geothermal brine solutions had good cyclability. These demonstrations provide a promising way for making low-cost, large-scale LTO electrode materials for energy storage applications.« less