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Morphological Dependence of Lithium Insertion in Nanocrystalline TiO2(B) Nanoparticles and Nanosheets
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posted on 2015-12-16, 21:39 authored by Anthony
G. Dylla, Penghao Xiao, Graeme Henkelman, Keith J. StevensonThe lithium insertion behavior of nanoparticle (3-D) and nanosheet
(2-D) architectures of TiO2(B) is quite different, as observed
by differential capacity plots derived from galvanostatic charging/discharge
experiments. DFT+U calculations show unique lithiation
mechanisms for the different nanoarchitectures. For TiO2(B) nanoparticles, A2 sites near equatorial TiO6 octahedra
are filled first, followed by A1 sites near axial TiO6 octahedra.
No open-channel C site filling is observed in the voltage range studied.
Conversely, TiO2(B) nanosheets incrementally fill C sites,
followed by A2 and A1. DFT+U calculations suggest
that the different lithiation mechanisms are related to the elongated
geometry of the nanosheet along the a-axis that reduces
Li+–Li+ interactions between C and A2
sites. The calculated lithiation potentials and degree of filling
agree qualitatively with the experimentally observed differential
capacity plots.