Bulk and grain-boundary ionic conductivity in sodium zirconophosphosilicate Na3Zr2(SiO4)2PO4 (NASICON)

• Published in: Chemical physics letters Vol. 701; pp. 147 - 150
• Main Authors: Lunghammer, S., Ma, Q., Rettenwander, D., Hanzu, I., Tietz, F., Wilkening, H.M.R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2018
• Subjects: Broadband impedance spectroscopy; Grain boundaries; Ion transport; Solid electrolytes; Grain boundaries; Ion transport; Broadband impedance spectroscopy; Solid electrolytes
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/j.cplett.2018.04.037

[Display omitted] •Na3Zr2(SiO4)2PO4 prepared via a solution-assisted route shows hyperionic properties.•Fortunately, grain boundaries do not block long-range Na ion transport.•Bulk and grain boundary ion transport are of the same order of magnitude. Sodium zirconophosphosilicates (Na1+xZr2(P1-xSixO4)3 (0<x<3)) currently experience a kind of renaissance as promising ceramic electrolytes for safe all-solid-state Na batteries. Such energy storage systems are an emerging option for next-generation technologies with attractive cost due to the use of abundant elements as sodium. To identify the right candidates their ion transport properties need to be precisely studied. In many cases less is known about the contributions of blocking grain boundaries to the overall charge carrier transport. Here, we took advantage of broadband impedance and conductivity spectroscopy carried out at sufficiently low temperature to make visible these two contributions for polycrystalline Na3Zr2(SiO4)2PO4. It turned out that ion transport across the grain boundaries of a sintered pellet do not greatly hinder long-range ion dynamics. While bulk ion dynamics in Na3Zr2(SiO4)2PO4 is characterized by 1.0 mS cm−1, the grain boundary ionic conductivity is only slightly lower viz. 0.7 mS cm−1. The latter value is of large practical interest as it allows the realization of all-solid-state Na batteries without strong interfering resistances from grain boundaries.