Simulations and Analyses of Li₄and Li₆ (Thio)Boracites As Promising Li Ion Conducting Electrolytes for All-Solid-State Batteries

The naturally occurring magnesium borate mineral, Mg₃B₇O₁₃Cl, is characterized by a rigid framework of B-O bonds together with a regular void structure, ideally forming crystals in a face-centered cubic structure. Several structurally related fast Li ion conducting boracites and thioboracites have been synthesized, including Li₄B₇O₁₂Cl [1], Li₄Al₃B₄O₁₂Cl [2], and Li₆B₇S₁₃I [3]. In previous work [4], we have shown that the high ionic conductivity of all of these materials is related to the occurrence of natural interstitial Li sites due to the high symmetry of the crystalline structures. In this presentation, we report the results of computational analyses and simulations of the extended family of Li₄ and Li₆ ion-conducting (thio)boracites in predicted crystalline forms, including face-centered rhombohedral R3c structures of Li₄B₇S₁₂Cl, Li₆B₇O₁₃Cl, and Li₆Al₃B₄O₁₃Cl as well as a monoclinic Cc structure of Li₆B₇S₁₃Cl.



[1] W. Jeitschko, et al., Acta Crystallogr. Sect. B 33, 2767 (1977)

[2] K. Kajihara, et al., Bull. Chem. Soc. Japan 90, 1279 (2017)

[3] K. Kaup, et al., J. Am. Chem. Soc. 143, 6952 (2021)

[4] Y. Li et al., Phys. Rev. Materials 6, 025401 (2022)