Promoting Persistent Superionic Conductivity in Sodium Monocarba-closo-dodecaborate NaCB11H12 via Confinement within Nanoporous Silica
Journal article, 2021

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 similar to 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.


Mikael Andersson

Chalmers, Physics, Subatomic and Plasma Physics

Vitalie Stavila

Sandia National Laboratories

Alexander V. Skripov

Russian Academy of Sciences

Mirjana Dimitrievska

Swiss Federal Institute of Technology in Lausanne (EPFL)

National Institute of Standards and Technology (NIST)

National Renewable Energy Laboratory

Malgorzata T. Psurek

University of Maryland

National Institute of Standards and Technology (NIST)

Juscelino B. Leao

National Institute of Standards and Technology (NIST)

Olga A. Babanova

Russian Academy of Sciences

Roman V. Skoryunov

Russian Academy of Sciences

Alexei V. Soloninin

Russian Academy of Sciences

Maths Karlsson

Chalmers, Chemistry and Chemical Engineering, Energy and Material, Environmental Inorganic Chemistry 2

Terrence J. Udovic

University of Maryland

National Institute of Standards and Technology (NIST)

Journal of Physical Chemistry C

1932-7447 (ISSN) 1932-7455 (eISSN)

Vol. 125 30 16689-16699

Subject Categories

Inorganic Chemistry

Materials Chemistry

Condensed Matter Physics



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