化学
离子电导率
四方晶系
中子衍射
离子键合
快离子导体
分析化学(期刊)
结晶学
拉曼光谱
中子散射
大气温度范围
晶体结构
核磁共振
离子
散射
物理化学
电解质
热力学
色谱法
光学
物理
有机化学
电极
作者
Oliver Maus,Matthias T. Agne,Till Fuchs,Paul Till,Björn Wankmiller,Josef Maximilian Gerdes,Rituraj Sharma,Michael Heere,Niina Jalarvo,Omer Yaffe,Michael Ryan Hansen,Wolfgang G. Zeier
摘要
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.
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