Phase Behavior, Structural Dynamics, and Ionic Conductivity in Perhalogenated Lithium Closo-Dodecaborates

Published

June 23, 2026

Author(s)

Agnieszka Prus, Hui Wu, Wei Zhou, Austin Bhandarkar, Jr. Teprovich, Karol Fijalkowski, A. Talin, Vitalie Stavila

Abstract

Solid electrolytes with suitable conductivity and stability are a key element in overcoming the inherent drawbacks of liquid organic electrolytes in advanced battery systems. This requires comprehensive research into ion transport in various types of solid compounds in order to understand the complex relationships between their composition, structure, and properties. In this paper, we systematically examine the crystal structures and ion transport properties of the perhalogenated lithium closo-dodecaborate salts Li2B12X12, where X = F, Cl, Br, and I. The compounds were isolated in anhydrous form and their structures determined by X-ray diffraction over a wide temperature range. Additional characterization was performed using thermal analysis, FTIR, and Raman spectroscopy, while DFT calculations were employed to rationalize the observed trends. Li2B12F12 crystallizes in the Cmca space group, while the other salts adopt the Pn3̅ symmetry. The Li2B12Cl12 and Li2B12Br12 compounds exhibit polymorphic transformations with transition temperatures around 859 and 865 K, respectively, which are well above that of Li2B12H12. This behavior likely arises from the larger size and greater mass of the perhalogenated anions, which hinder reorientational dynamics at lower temperatures. In contrast, at high-temperatures the disordered phases exhibit high Li+ ionic conductivity values, reaching 0.12 S cm−1 for Li2B12Cl12 and 0.052 S cm−1 for Li2B12Br12 (at ≈870 K). Overall, the synergistic blend of structural disorder and inherent thermal and electrochemical stability positions the perhalogenated closo-dodecaborates as a robust platform for the development of high-performance electrolytes for various electrochemical devices.

Citation

Chemistry of Materials

Volume

38

Issue

12

Pub Type

Journals

Download Paper

https://doi.org/10.1021/acs.chemmater.6c00218

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Keywords

perhalogenated closo-dodecaborate, lithium ionic conductor, X-ray crystallography, First-principles calculations, conductivity

Citation

Prus, A. , Wu, H. , Zhou, W. , Bhandarkar, A. , Teprovich, J. , Fijalkowski, K. , Talin, A. and Stavila, V. (2026), Phase Behavior, Structural Dynamics, and Ionic Conductivity in Perhalogenated Lithium Closo-Dodecaborates, Chemistry of Materials, [online], https://doi.org/10.1021/acs.chemmater.6c00218, https://nps-ext.nist.gov/nps/nps_public_api/api/Publication/file/961611 (Accessed November 12, 2026)

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