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Origin of High Ionic Conductivity of Sc‐Doped Sodium‐Rich NASICON Solid‐State Electrolytes
Author(s) -
Sun Fei,
Xiang Yuxuan,
Sun Qian,
Zhong Guiming,
Banis Mohammad Norouzi,
Liu Yulong,
Li Ruying,
Fu Riqiang,
Zheng Matthew,
Sham TsunKong,
Yang Yong,
Sun Xuhui,
Sun Xueliang
Publication year - 2021
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202102129
Subject(s) - fast ion conductor , materials science , ionic conductivity , ion , electrolyte , ionic bonding , sodium , conductivity , doping , monoclinic crystal system , inorganic chemistry , crystal structure , crystallography , chemistry , optoelectronics , organic chemistry , electrode , metallurgy
Substitution of liquid electrolyte with solid‐state electrolytes (SSEs) has emerged as a very urgent and challenging research area of rechargeable batteries. NASICON (Na 3 Zr 2 Si 2 PO 12 ) is one of the most potential SSEs for Na‐ion batteries due to its high ionic conductivity and low thermal expansion. It is proven that the ionic conductivity of NASICON can be improved to 10 −3 S cm −1 by Sc‐doping, of which the mechanism, however, has not been fully understood. Herein, a series of Na 3+x Sc x Zr 2−x Si 2 PO 12 (0 ≤ x ≤ 0.5) SSEs are prepared. To gain a deep insight into the ion transportation mechanism, synchrotron‐based X‐ray absorption spectroscopy (XAS) is employed to characterize the electronic structure, and solid‐state nuclear magnetic resonance (SS‐NMR) is used to analyze the dynamics. In this study, Sc is successfully doped into Na 3 Zr 2 Si 2 PO 12 to substitute Zr atoms. The redistribution of sodium ions at certain specific sites is proven to be critical for sodium ion movement. For x ≤ 0.3, the promotion of sodium ion movement is attributed to sodium ion concentration increase at the Na2 sites and decrease at the Na1 and Na3 sites. For x > 0.3, the inhibition of sodium ion movement is due to the phase change from monoclinic to rhombohedral and an increasing impurity content.