Title: Structural and Electrochemical Characteristics of Ca-Doped “Flower-like” Li₄Ti₅O₁₂ Motifs as High-Rate Anode Materials for Lithium-Ion Batteries

Abstract

Doped motifs offer an intriguing structural pathway toward improving conductivity for battery applications. Specifically, Ca-doped, three-dimensional “flower-like” Li_4–xCa_xTi₅O₁₂ (“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 dopant 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 Ti³⁺ 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_xTi₅O₁₂ (“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%more » 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 Li₄Ti₅O₁₂, 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 Li₄Ti₅O₁₂.« less

Authors:

Wang, Lei  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-6348-8344"

Zhang, Yiman ^[1]; Guo, Haoyue ^[1]; Li, Jing ^[2]; Stach, Eric A.  ^[2];

• Search DOE PAGES for author "Stach, Eric A."
• Search DOE PAGES for ORCID "0000-0002-3366-2153"

Tong, Xiao ^[3]; Takeuchi, Esther S.  ^[2];

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• Search DOE PAGES for ORCID "0000-0001-8518-1047"

Takeuchi, Kenneth J. ^[2]; Liu, Ping  ^[3];

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• Search DOE PAGES for ORCID "0000-0001-8363-070X"

Marschilok, Amy C.  ^[2];

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• Search DOE PAGES for ORCID "0000-0001-9174-0474"

Wong, Stanislaus S.  ^[2]

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• Search DOE PAGES for ORCID "0000-0001-7351-0739"

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+ Show Author Affiliations

1. Stony Brook Univ., NY (United States)
2. Stony Brook Univ., NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
3. Brookhaven National Lab. (BNL), Upton, NY (United States)

Publication Date:

Mon Jan 22 00:00:00 EST 2018

Research Org.:

Brookhaven National Laboratory (BNL), Upton, NY (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Mesoscale Transport Properties (m2M)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1425064

Report Number(s):

BNL-200081-2018-JAAM
Journal ID: ISSN 0897-4756; TRN: US1802025

Grant/Contract Number:  

SC0012704

Resource Type:

Accepted Manuscript

Journal Name:

Chemistry of Materials

Additional Journal Information:

Journal Volume: 30; Journal Issue: 3; Journal ID: ISSN 0897-4756

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 25 ENERGY STORAGE