%0 Journal Article
%A Wang, Lei
%A Zhang, Yiman
%A Guo, Haoyue
%A Li, Jing
%A Stach, Eric A.
%A Tong, Xiao
%A Takeuchi, Esther S.
%A Takeuchi, Kenneth J.
%A Liu, Ping
%A Marschilok, Amy C.
%A Wong, Stanislaus S.
%D 2018
%T Structural and Electrochemical Characteristics of
Ca-Doped “Flower-like” Li4Ti5O12 Motifs as High-Rate Anode Materials for Lithium-Ion Batteries
%U https://acs.figshare.com/articles/journal_contribution/Structural_and_Electrochemical_Characteristics_of_Ca-Doped_Flower-like_Li_sub_4_sub_Ti_sub_5_sub_O_sub_12_sub_Motifs_as_High-Rate_Anode_Materials_for_Lithium-Ion_Batteries/5807094
%R 10.1021/acs.chemmater.7b03847.s001
%2 https://acs.figshare.com/ndownloader/files/10262787
%K 20 C
%K XPD
%K XPS
%K ion diffusion coefficients
%K XRD
%K Ca-doped Li 4 Ti 5 O 12
%K High-Rate Anode Materials
%K Li 4 Ti 5 O 12
%K TEM
%K SEM
%K ICP-OES
%K LTO
%K CV
%K EDS
%K spectroscopy
%K EIS
%K cycling stability
%K DFT
%K Lithium-Ion Batteries Doped motifs offer
%K Calcium dopant ions
%K charge transfer conductivity
%X Doped
motifs offer an intriguing structural pathway toward improving
conductivity for battery applications. Specifically, Ca-doped, three-dimensional
“flower-like” Li4–xCaxTi5O12 (“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 Li4–xCaxTi5O12 (“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
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.
%I ACS Publications