Oral Presentation The 35th Biennial Conference of the Society of Crystallographers in Australia and New Zealand 2024 (Crystal 35)

Ionic Conductivity and Local Structure in Sodium Perovskite Solid-State Electrolytes (108773)

Mia Brennan 1 , Fredrick Marlton 2 , Biswaranjan Mohanty 3 , Bryce Mullens 4 , Chris D Ling 1
  1. School of Chemistry, University of Sydney, Sydney, NSW, Australia
  2. School of Mathematical and Physical Sciences, University of Technology Sydney, Sydney, NSW, Australia
  3. Sydney Analytical, University of Sydney, Sydney, NSW, Australia
  4. Department of Chemistry, Stony Brook University, Stony Brook, New York, United States of America

The growing need for safe, reliable energy storage has brought the search for stable, high performance solid electrolytes to the forefront of battery material research. One approach to achieve these goals is to use the highly versatile perovskite structure. This structure, with the general formula ABX3, allows for a wide range of dopants which can be used to tailor the resulting ionic conductivities of perovskite solid electrolytes [1]. However, an overall mechanism remains elusive.

Recently, it has been shown that the ionic conduction of the sodium-based perovskite Na1/2La1/2ZrO3 can be improved through the substitution of Sr2+ onto the A site, reaching a maximum ionic conductivity in Na1/2-xLa1/2-xSr2xZrO3 at x = 1/6. Zhao et al. propose that this increase in ionic conductivity is due to the widening of sodium conduction pathways caused by the addition of Sr2+ [2]. Our experiments have shown that doping the A site with larger Ba2+ cations further increased the ionic conductivity and sodium mobility, agreeing with the mechanism proposed by Zhao et al.

However, unlike the Sr2+ series, we have found that the ionic conductivity of the Ba2+ series reaches a local maximum at  x = 1/6 but has a global maximum at x = 7/32, coinciding with disorder in the long-range structure as evidenced by X-ray diffraction. We have quantified the local cation ordering in this system using a combination of total scattering data obtained at the Institut Laue-Langevin (ILL), Grenoble, EXAFS data collected at the Australian Synchrotron, and solid-state NMR collected at the University of Sydney to gain a better understanding of ionic conductivity in this system.

  1. Yan, S., et al., Perovskite Solid-State Electrolytes for Lithium Metal Batteries. Batteries-Basel, 2021. 7(4).
  2. Zhao, Y.Z., et al., Synthesis and characterization of a new perovskite-type solid-state electrolyte of Na1/3La1/3Sr1/3ZrO3 for all solid-state sodium-ion batteries. Journal of Alloys and Compounds, 2019. 783: p. 219-225.