Atomic scale imaging of structural changes in solid electrolyte lanthanum lithium niobate upon annealing

Xiaobing Hu, Craig A.J. Fisher, Shunsuke Kobayashi, Yumi H. Ikuhara, Yasuyuki Fujiwara, Keigo Hoshikawa, Hiroki Moriwake, Keiichi Kohama, Hideki Iba, Yuichi Ikuhara*

*Corresponding author for this work

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

La(1-x)/3LixNbO3 (LLNbO) is a promising electrolyte material for solid-state lithium-ion batteries because it is stable in contact with Li metal and contains a high concentration of intrinsic Li-ion vacancies. One strategy for improving its ionic conductivity and making it more competitive with other solid-state Li-ion electrolytes is to disorder the Li-ion vacancies by appropriate post-synthesis heat treatment, e.g., annealing. In this study, we examine the effects of annealing on single crystals of LLNbO with Li contents x = 0.07 and 0.13 based on simultaneous atomic resolution high angle annular dark field and annular bright field imaging methods using state-of-the-art aberration corrected scanning transmission electron microscopes. It is found that La modulation within A1 layers of the cation-deficient layered perovskite structure becomes more diffuse after annealing. In addition, some La atoms move to A-site positions and O4 window positions in the nominally vacant A2 layer, while O atom columns in this layer become rumpled in the [001]p direction, indicating that the NbO6 octahedra are more heavily distorted after annealing. The observed crystal structure differences between as-prepared and annealed single crystals explain the drop in Li-ion conductivities of LLNbO single crystals after heat treatment.

Original languageEnglish (US)
Pages (from-to)211-219
Number of pages9
JournalActa Materialia
Volume127
DOIs
StatePublished - Apr 1 2017

Keywords

  • Aberration corrected scanning transmission electron microscopy
  • Layered perovskite
  • Solid electrolyte
  • Solid-state Li-ion battery
  • Structure characterization

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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    Hu, X., Fisher, C. A. J., Kobayashi, S., Ikuhara, Y. H., Fujiwara, Y., Hoshikawa, K., Moriwake, H., Kohama, K., Iba, H., & Ikuhara, Y. (2017). Atomic scale imaging of structural changes in solid electrolyte lanthanum lithium niobate upon annealing. Acta Materialia, 127, 211-219. https://doi.org/10.1016/j.actamat.2017.01.028