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@ARTICLE{Redhammer:903602,
author = {Redhammer, Günther J. and Badami, Pavan and Meven, Martin
and Ganschow, Steffen and Berendts, Stefan and Tippelt,
Gerold and Rettenwander, Daniel},
title = {{W}et-{E}nvironment-{I}nduced {S}tructural {A}lterations in
{S}ingle- and {P}olycrystalline {LLZTO} {S}olid
{E}lectrolytes {S}tudied by {D}iffraction {T}echniques},
journal = {ACS applied materials $\&$ interfaces},
volume = {13},
number = {1},
issn = {1944-8244},
address = {Washington, DC},
publisher = {Soc.},
reportid = {FZJ-2021-05256},
pages = {350 - 359},
year = {2021},
abstract = {Li7La3Zr2O12 (LLZO) is one of the potential candidates for
Li metal-based solid-state batteries owing to its high Li+
conductivity (≈10$^{–3}$ S cm$^{–1}$) at room
temperature and large electrochemical stability window.
However, LLZO undergoes protonation under the influence of
moisture-forming Li2CO3 layers, thereby affecting its
structural and transport properties. Therefore, a detailed
understanding on the impact of the exchange of H+ on Li+
sites on structural alteration and kinetics under the
influence of wet environments is of great importance. The
present study focuses on the Li+/H+ exchange in
single-crystal and polycrystal Li6La3ZrTaO12 (LLZTO) garnets
prepared using the Czochralski method and solid-state
reactions subjected to weathering in air, aqueous solutions
at room temperature, and in aqueous solution at 363 K using
X-ray diffraction (XRD) and neutron diffraction (ND)
techniques. Based on 36 single-crystal diffraction and 88
powder diffraction measurements, we found that LLZTO
crystallizes with space group (SG) Ia3̅d with Li located in
96h (Li(2)) and 24d (Li(1)) sites, whereas the latter one is
displaced toward the general position 96h forming shorter
Li(1)–Li(2) jump distances. The degradation in air, wet
air, water, and acetic acid leads to a Li+/H+ exchange that
preferably takes place at the 24d site, which is in contrast
to previous reports. Higher Li+/H+ was observed for LLZTO
aged in water at 363 K that reduced the symmetry to SG
I4̅3d from SG Ia3̅d. This symmetry reduction was found to
be related to the site occupation behavior of Li at the
tetrahedral 12a site in SG I4̅3d. Moreover, Li+ is
exchanged by H+ preferably at the 48e site (equivalent to
96h site). We also found that the equilibrium H+
concentrations in all media tested remains very similar,
which is related to the H+ diffusion in the LLZTO-controlled
exchange process. Only the increase in temperature led to a
significant increase in the exchange capacity as well as in
the Li+/H+ exchange rate. Overall, we found that the
exchange rate, exchange capacity, site occupation behavior
of Li+ and H+, as well as the structural stability of LLZTO,
strongly depend on the composition. These findings suggest
that measurements on a single LLZTO variant sample do not
lead to a general conclusion for all garnets to guide the
field toward better materials. In contrast, each composition
has to be analyzed exclusively to understand the interplay
of composition, structure, and exchange kinetic properties.},
cin = {JCNS-FRM-II / MLZ / JARA-FIT / JCNS-2},
ddc = {600},
cid = {I:(DE-Juel1)JCNS-FRM-II-20110218 / I:(DE-588b)4597118-3 /
$I:(DE-82)080009_20140620$ / I:(DE-Juel1)JCNS-2-20110106},
pnm = {6G4 - Jülich Centre for Neutron Research (JCNS) (FZJ)
(POF4-6G4)},
pid = {G:(DE-HGF)POF4-6G4},
experiment = {EXP:(DE-MLZ)HEIDI-20140101},
typ = {PUB:(DE-HGF)16},
pubmed = {33372519},
UT = {WOS:000611066000030},
doi = {10.1021/acsami.0c16016},
url = {https://juser.fz-juelich.de/record/903602},
}