Anionic Sublattices in Halide Solid Electrolytes: A Case Study with the High-Pressure Phase of Li3ScCl6

Fenghua Ding; Atsunori Doi; Takafumi Ogawa; Hiroki Ubukata; Tong Zhu; Daichi Kato; Cédric Tassel; Itaru Oikawa; Naoki Inui; Satoru Kuze; Tsutomu Yamabayashi; Kotaro Fujii; Masatomo Yashima; Xing Ou; Zhijian Wang; Xiaobo Min; Koji Fujita; Hitoshi Takamura; Akihide Kuwabara; Tianren Zhang; Kent J Griffith; Zhang Lin; Liyuan Chai; Hiroshi Kageyama

doi:10.1002/anie.202401779

Anionic Sublattices in Halide Solid Electrolytes: A Case Study with the High-Pressure Phase of Li₃ScCl₆

Angew Chem Int Ed Engl. 2024 Apr 8;63(15):e202401779. doi: 10.1002/anie.202401779. Epub 2024 Mar 5.

Authors

Fenghua Ding¹, Atsunori Doi², Takafumi Ogawa³, Hiroki Ubukata¹, Tong Zhu¹, Daichi Kato¹, Cédric Tassel¹, Itaru Oikawa⁴, Naoki Inui¹, Satoru Kuze¹, Tsutomu Yamabayashi⁵, Kotaro Fujii⁶, Masatomo Yashima⁶, Xing Ou⁷, Zhijian Wang⁸, Xiaobo Min⁷, Koji Fujita⁹, Hitoshi Takamura⁴, Akihide Kuwabara³, Tianren Zhang¹⁰, Kent J Griffith¹⁰, Zhang Lin⁷, Liyuan Chai⁷, Hiroshi Kageyama¹

Affiliations

¹ Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University Nishikyo-ku, Kyoto, 615-8510, Japan.
² Advanced Materials Development Laboratory, Sumitomo Chemical Co. Ltd., Tsukuba, 300-3294, Japan.
³ Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya, 456-8587, Japan.
⁴ Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan.
⁵ Energy & Functional Materials Research Laboratory, Sumitomo Chemical Co. Ltd., Niihama, 792-8521, Japan.
⁶ Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1-W4-17, O-okayama, Meguro-ku, Tokyo, 152-8551, Japan.
⁷ School of Metallurgy and Environment, Central South University, Changsha, 410083, PR China.
⁸ Hunan Rare Earth Metal Materials Research Institute Co. Ltd., Changsha, 410126, PR China.
⁹ Department of Material Chemistry, Graduate School of Engineering, Kyoto, University, Nishikyo-ku, Kyoto, 615-8510, Japan.
¹⁰ Department of Chemistry & Biochemistry, University of California, San Diego, La Jolla, California, 92093, USA.

PMID: 38363076
DOI: 10.1002/anie.202401779

Abstract

The Li₃MX₆ compounds (M=Sc, Y, In; X=Cl, Br) are known as promising ionic conductors due to their compatibility with typical metal oxide cathode materials. In this study, we have successfully synthesized γ-Li₃ScCl₆ using high pressure for the first time in this family. Structural analysis revealed that the high-pressure polymorph crystallizes in the polar and chiral space group P6₃mc with hexagonal close-packing (hcp) of anions, unlike the ambient-pressure α-Li₃ScCl₆ and its spinel analog with cubic closed packing (ccp) of anions. Investigation of the known Li₃MX₆ family further revealed that the cation/anion radius ratio, r_M/r_X, is the factor that determines which anion sublattice is formed and that in γ-Li₃ScCl₆, the difference in compressibility between Sc and Cl exceeds the ccp r_M/r_X threshold under pressure, enabling the ccp-to-hcp conversion. Electrochemical tests of γ-Li₃ScCl₆ demonstrate improved electrochemical reduction stability. These findings open up new avenues and design principles for lithium solid electrolytes, enabling routes for materials exploration and tuning electrochemical stability without compositional changes or the use of coatings.

Keywords: anion sublattice; high pressure; non-centrosymmetric structure; solid electrolyte; structure stability.

Grants and funding

JP22H04914; JPJSCCA20200004; JP22H05143; JP22H05146; JP23H04618/Japan Society for the Promotion of Science