Crystal Structures, Local Atomic Environments, and Ion Diffusion Mechanisms of Scandium-Substituted Sodium Superionic Conductor (NASICON) Solid Electrolytes
Crystal Structures, Local Atomic Environments, and Ion Diffusion Mechanisms of Scandium-Substituted Sodium Superionic Conductor (NASICON) Solid Electrolytes
复制标题
钪取代的钠快离子导体（NASICON）固体电解质的晶体结构、局部原子环境及离子扩散机制
DOI：
10.1021/acs.chemmater.7b05237
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发表时间：
2018-04-24
影响因子：
8.6
通讯作者：
Masquelier, Christian
中科院分区：
文献类型：
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作者：
Deng, Yue;Eames, Christopher;Masquelier, Christian
开发用于全固态电池的新型固体电解液的重要性引起了人们对NASICON型材料的浓厚兴趣。本文研究了Sc~(3+)取代的NASICON化合物(NaScZr2-x)-Sc-3-Zr-x(SiO4)(2-x)(PO4)(1+x)(记为N3)和Na2ScyZr2-y(SiO4)(1-y)(PO4)(2+y)(记为N2)(x，y=0-1)作为固体电池用钠离子导电电解液的模型。用粉末X射线衍射仪(XRD)、中子粉末衍射仪(NPD)以及固体核磁共振谱(Na-23、P-31和Si-29)表征了Sc~(3+)取代对晶体结构和局域原子环境的影响。在295~473K之间，观察到N3组分在BarC晶胞上由单斜晶系C2/c向三方晶系R(3)的转变，而在此温度范围内，氮气组分在Barc晶胞上以三方晶系R(3)晶化。交流阻抗谱(AC)、分子动力学(MD)和高温Na-23核磁共振研究表明，随着Sc~(3+)浓度的增加，离子电导率(473K时约为10~(-4)S/厘米)减小，离子扩散活化能增大。Na-23核磁共振实验表明，虽然长距离扩散路径是三维的，但在核磁共振的局域原子尺度上，Na+离子的运动本质是二维的。此外，结合MD、键价、最大熵/Rietveld和van Hove关联方法，揭示了Na+离子在这些NASICON材料中的扩散是三维的，并且Na(1)和Na(2)位之间存在着连续的钠离子交换。
The importance of exploring new solid electro-lytes for all-solid-state batteries has led to significant interest in NASICON-type materials. Here, the Sc3+-substituted NASICON compositions (NaScZr2-x)-Sc-3-Zr-x(SiO4)(2-x)(PO4)(1+x) (termed N3) and Na2ScyZr2-y(SiO4)(1-y)(PO4)(2+y) (termed N2) (x, y = 0-1) are studied as model Na+-ion conducting electrolytes for solid-state batteries. The influence of Sc3+ substitution on the crystal structures and local atomic environments has been characterized by powder X-ray diffraction (XRD) and neutron powder diffraction (NPD), as well as solid-state Na-23, P-31, and Si-29 nuclear magnetic resonance (NMR) spectroscopy. A phase transition between 295 and 473 K from monoclinic C2/c to rhombohedral R (3) over barc is observed for the N3 compositions, while N2 compositions crystallize in a rhombohedral R (3) over barc unit cell in this temperature range. Alternating current (AC) impedance spectroscopy, molecular dynamics (MD), and high temperature Na-23 NMR studies are in good agreement, showing that, with a higher Sc3+ concentration, the ionic conductivity (of about 10(-4) S/cm at 473 K) decreases and the activation energy for ion diffusion increases. Na-23 NMR experiments indicate that the nature of the Na+-ion motion is two-dimensional on the local atomic scale of NMR although the long-range diffusion pathways are three-dimensional. In addition, a combination of MD, bond valence, maximum entropy/Rietveld, and van Hove correlation methods has been used to reveal that the Na+-ion diffusion in these NASICON materials is three-dimensional and that there is a continuous exchange of sodium ions between Na(1) and Na(2) sites.