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Title: Freeze Tape Cast Thick Mo Doped Li 4Ti 5O 12 Electrodes for Lithium-Ion Batteries

Abstract

Lithium titanate (Li 4Ti 5O 12) powders with and without molybdenum doping (LTO and MoLTO respectively) were synthesized by a solid-state method and used to fabricate electrodes on Cu foil using a normal tape-cast method and a novel freeze-tape-cast method. Modest molybdenum doping produces a significant electronic conductivity increase (e.g. 1 mS cm -1 for MoLTO vs 10 -7 mS cm -1 for LTO) that is thought to reflect a partial Ti 4+ reduction to Ti 3+ with charge compensation by the Mo 6+ dopant, producing a stable mixed-valent Ti 4+/3+ state. Freeze-tape-cast electrodes were fabricated by a variant of the normal tape-cast method that includes a rapid freezing step in which the solvent in the Cu-foil-supported slurry is rapidly frozen on a cold finger then subsequently sublimed to create unidirectional columnar macropores in the electrode. The resulting electrodes exhibit high porosity and low tortuosity which enhances electrolyte accessibility throughout the full electrode thickness. Freeze-tape-cast electrodes subjected to galvanostatic charge-discharge testing as cathodes in cells vs. a lithium metal anode exhibit higher specific capacity and lower capacity loss at high discharge rates compared with normal-tape-cast electrodes of the same mass loading, despite the fact that the freeze-tape-cast electrodes are nearlymore » twice as thick as the normal tape cast electrodes.« less

Authors:
 [1];  [1];  [2];  [1]
  1. Clemson Univ., SC (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); National Science Foundation (NSF)
OSTI Identifier:
1394412
Grant/Contract Number:
AC05-00OR22725; CMMI 1502392
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 164; Journal Issue: 12; Journal ID: ISSN 0013-4651
Publisher:
The Electrochemical Society
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; electronic conductivity; lithium battery; lithium titanate

Citation Formats

Ghadkolai, Milad Azami, Creager, Stephen, Nanda, Jagjit, and Bordia, Rajendra K. Freeze Tape Cast Thick Mo Doped Li4Ti5O12 Electrodes for Lithium-Ion Batteries. United States: N. p., 2017. Web. doi:10.1149/2.1311712jes.
Ghadkolai, Milad Azami, Creager, Stephen, Nanda, Jagjit, & Bordia, Rajendra K. Freeze Tape Cast Thick Mo Doped Li4Ti5O12 Electrodes for Lithium-Ion Batteries. United States. doi:10.1149/2.1311712jes.
Ghadkolai, Milad Azami, Creager, Stephen, Nanda, Jagjit, and Bordia, Rajendra K. Wed . "Freeze Tape Cast Thick Mo Doped Li4Ti5O12 Electrodes for Lithium-Ion Batteries". United States. doi:10.1149/2.1311712jes. https://www.osti.gov/servlets/purl/1394412.
@article{osti_1394412,
title = {Freeze Tape Cast Thick Mo Doped Li4Ti5O12 Electrodes for Lithium-Ion Batteries},
author = {Ghadkolai, Milad Azami and Creager, Stephen and Nanda, Jagjit and Bordia, Rajendra K.},
abstractNote = {Lithium titanate (Li4Ti5O12) powders with and without molybdenum doping (LTO and MoLTO respectively) were synthesized by a solid-state method and used to fabricate electrodes on Cu foil using a normal tape-cast method and a novel freeze-tape-cast method. Modest molybdenum doping produces a significant electronic conductivity increase (e.g. 1 mS cm-1 for MoLTO vs 10-7 mS cm-1 for LTO) that is thought to reflect a partial Ti4+ reduction to Ti3+ with charge compensation by the Mo6+ dopant, producing a stable mixed-valent Ti4+/3+ state. Freeze-tape-cast electrodes were fabricated by a variant of the normal tape-cast method that includes a rapid freezing step in which the solvent in the Cu-foil-supported slurry is rapidly frozen on a cold finger then subsequently sublimed to create unidirectional columnar macropores in the electrode. The resulting electrodes exhibit high porosity and low tortuosity which enhances electrolyte accessibility throughout the full electrode thickness. Freeze-tape-cast electrodes subjected to galvanostatic charge-discharge testing as cathodes in cells vs. a lithium metal anode exhibit higher specific capacity and lower capacity loss at high discharge rates compared with normal-tape-cast electrodes of the same mass loading, despite the fact that the freeze-tape-cast electrodes are nearly twice as thick as the normal tape cast electrodes.},
doi = {10.1149/2.1311712jes},
journal = {Journal of the Electrochemical Society},
number = 12,
volume = 164,
place = {United States},
year = {Wed Aug 30 00:00:00 EDT 2017},
month = {Wed Aug 30 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
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  • 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
  • Pure and metal (Cu, Al, Sn, and V)-doped Li{sub 4}Ti{sub 5}O{sub 12} powders are prepared with solid-state reaction method. The effects of dopants on the physical and electrochemical properties are characterized by using TGA, XRD, and SEM. Compared with pure Li{sub 4}Ti{sub 5}O{sub 12}, metal-doped Li{sub 4}Ti{sub 5}O{sub 12} powders show structural stability and enhanced lithium ion diffusivity brought by doped metal ions. Voltage characteristics and initial charge–discharge characteristics according to the C rates in pure and metal-doped Li{sub 4}Ti{sub 5}O{sub 12} electrode materials are studied. Pure Li{sub 4}Ti{sub 5}O{sub 12} powder shows a relatively good discharge capacity of 164more » mAh/g at a rate 0.2C, and some of metal-doped Li{sub 4}Ti{sub 5}O{sub 12} powders show higher discharge capacities. Metal-doped Li{sub 4}Ti{sub 5}O{sub 12} powders are promising candidates as anode materials for lithium-ion batteries.« less
  • 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 2more » 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 near zero deformation of the dual phase structure, which explains its excellent cycle stability.« less