TY  - JOUR
AU  - Maus, Oliver
AU  - Agne, Matthias T.
AU  - Fuchs, Till
AU  - Till, Paul S.
AU  - Wankmiller, Björn
AU  - Gerdes, Josef Maximilian
AU  - Sharma, Rituraj
AU  - Heere, Michael
AU  - Jalarvo, Niina
AU  - Yaffe, Omer
AU  - Hansen, Michael Ryan
AU  - Zeier, Wolfgang G.
TI  - On the Discrepancy between Local and Average Structure in the Fast $Na^+$ Ionic Conductor $Na_{2.9}Sb_{0.9}W_{0.1}S_{4}$
JO  - Journal of the American Chemical Society
VL  - 145
IS  - 13
SN  - 0002-7863
CY  - Washington, DC
PB  - ACS Publications
M1  - FZJ-2023-02065
SP  - 7147 - 7158
PY  - 2023
AB  - Aliovalent substitution is a common strategy to improve the ionic conductivity of solid electrolytes for solid-state batteries. The substitution of SbS43– by WS42– in Na2.9Sb0.9W0.1S4 leads to a very high ionic conductivity of 41 mS cm–1 at room temperature. While pristine Na3SbS4 crystallizes in a tetragonal structure, the substituted Na2.9Sb0.9W0.1S4 crystallizes in a cubic phase at room temperature based on its X-ray diffractogram. Here, we show by performing pair distribution function analyses and static single-pulse 121Sb NMR experiments that the short-range order of Na2.9Sb0.9W0.1S4 remains tetragonal despite the change in the Bragg diffraction pattern. Temperature-dependent Raman spectroscopy revealed that changed lattice dynamics due to the increased disorder in the Na+ substructure leads to dynamic sampling causing the discrepancy in local and average structure. While showing no differences in the local structure, compared to pristine Na3SbS4, quasi-elastic neutron scattering and solid-state 23Na nuclear magnetic resonance measurements revealed drastically improved Na+ diffusivity and decreased activation energies for Na2.9Sb0.9W0.1S4. The obtained diffusion coefficients are in very good agreement with theoretical values and long-range transport measured by impedance spectroscopy. This work demonstrates the importance of studying the local structure of ionic conductors to fully understand their transport mechanisms, a prerequisite for the development of faster ionic conductors.
LB  - PUB:(DE-HGF)16
C6  - 36946557
UR  - <Go to ISI:>//WOS:000967981500001
DO  - DOI:10.1021/jacs.2c11803
UR  - https://juser.fz-juelich.de/record/1007410
ER  -