Promoting Persistent Superionic Conductivity in Sodium Monocarba-closo-dodecaborate NaCB11H12 via Confinement within Nanoporous Silica

Mikael Andersson, Vitalie Stavila, Alexander Skripov, Mirjana Dimitrievska, Malgorzata Psurek, Juscelino Leao, Olga Babanova, Roman Skoryunov, Alexei Soloninin, Maths Karlsson, Terrence Udovic

Research output: Contribution to journalArticlepeer-review

18 Scopus Citations

Abstract

Superionic phases of bulk anhydrous salts based on large cluster-like polyhedral (carba)borate anions are generally stable only well above room temperature, rendering them unsuitable as solid-state electrolytes in energy-storage devices that typically operate at close to room temperature. To unlock their technological potential, strategies are needed to stabilize these superionic properties down to subambient temperatures. One such strategy involves altering the bulk properties by confinement within nanoporous insulators. In the current study, the unique structural and ion dynamical properties of an exemplary salt, NaCB11H12, nanodispersed within porous, high-surface-area silica via salt-solution infiltration were studied by differential scanning calorimetry, X-ray powder diffraction, neutron vibrational spectroscopy, nuclear magnetic resonance, quasielastic neutron scattering, and impedance spectroscopy. Combined results hint at the formation of a nanoconfined phase that is reminiscent of the high-temperature superionic phase of bulk NaCB11H12, with dynamically disordered CB11H12– anions exhibiting liquid-like reorientational mobilities. However, in contrast to this high-temperature bulk phase, the nanoconfined NaCB11H12 phase with rotationally fluid anions persists down to cryogenic temperatures. Moreover, the high anion mobilities promoted fast-cation diffusion, yielding Na+ superionic conductivities of ~0.3 mS/cm at room temperature, with higher values likely attainable via future optimization. It is expected that this successful strategy for conductivity enhancement could be applied as well to other related polyhedral (carba)borate-based salts. Thus, these results present a new route to effectively utilize these types of superionic salts as solid-state electrolytes in future battery applications.
Original languageAmerican English
Pages (from-to)16689-16699
Number of pages11
JournalJournal of Physical Chemistry C
Volume125
Issue number30
DOIs
StatePublished - 2021

NREL Publication Number

  • NREL/JA-5900-80798

Keywords

  • differential scanning calorimetry
  • energy storage
  • negative ions
  • neutron scattering
  • nuclear magnetic resonance spectroscopy
  • salts
  • silica
  • solid electrolytes
  • solid-state batteries

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