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Sodium Superionic Conduction in Na2B12H12



Terrence J. Udovic, Matoaki Matsuo, Atsushi Unemoto, Kristina Verdal, Vitalie Stavila, Alexander V. Skripov, John J. Rush, Hitoshi Takamura, Shin-Ichi Orimo


The need for cheaper, Li-free battery technologies has prompted the search for new Na-ion-based electrolyte materials. One such material, Na2B12H12, undergoes an entropy-driven transition upon heating from an ordered monoclinic structure to a disordered cubic structure at around 529 K. Impedance measurements across the phase transition have indicated a nearly three-orders-of-magnitude jump in Na+ cation conductivity, approaching 0.1 S/cm. The unusually high cation mobility above the transition is a result of the "melting" of the Na+ cation sublattice within the body-centered-cubic (bcc)arrangement of the orientationally disordered B12H122- anions, similar to what is observed for the mobile Ag+ sublattice in the bcc phase of AgI. The high reorientational mobility, relatively large size, and quasispherical shape of the B12H122- anions may all play roles in facilitating Na+ diffusion. Superionicity, high-temperature stability, and low cost combine to make Na2B12H12 an attractive solid-state electrolyte for future Na-based batteries. It is probably that even better properties, i.e., lower phase-transition temperatures and higher ion conduction, can be realized, eg.g., via modification or subsitiution of the B12H122+ anions.
Chemical Communications


battery, cation vacancy, complex hydride, conductivity, impedance measurement, ion conductivity, Na cation, sodium, superionicity


Udovic, T. , Matsuo, M. , Unemoto, A. , , K. , Stavila, V. , , A. , Kasianowicz, J. , Takamura, H. and Orimo, S. (2014), Sodium Superionic Conduction in Na<sub>2</sub>B<sub>12</sub>H<sub>12</sub>, Chemical Communications, [online], (Accessed June 13, 2024)


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Created April 11, 2014, Updated February 19, 2017