Chemical Bond Covalency in Superionic Halide Solid‐State Electrolytes
Halide solid-state electrolytes (SSEs) are promising superionic conductors with high oxidative stability and ionic conductivity, making them attractive for all-solid-state lithium-ion batteries. However, most studies have focused on ion-stacking structures, overlooking the role of bond characteristics in ionic transport. Here, we investigate bond dynamics and the superionic transition (SIT) in bromide electrolyte, Li<sub>3</sub>InBr<sub>6</sub>, using synchrotron X-ray techniques and ab initio molecular dynamics (AIMD) simulations. We demonstrate that the SIT in halide SSEs is driven by a thermally induced transition in bonding character (ionic to covalent) rather than a change in crystal phase. AIMD simulations further reveal enhanced Li⁺ diffusion and collective anion motion at elevated temperatures. Expanding our study to Li<sub>3</sub>LnBr<sub>6</sub> (Ln = Gd, Tb, Ho, Tm, and Lu), we confirm the widespread occurrence of SIT in this material class, with Li<sub>3</sub>GdBr<sub>6</sub> exhibiting the highest ionic conductivity (5.2 mS cm<sup>-1</sup> at 298 K). More importantly, the ionic-covalent transition is highly tunable through electrolyte modifications, such as cation/anion substitution and synthesis methods. Our findings provide a new perspective on ionic transport, highlighting the critical role of chemical bond characteristics in halide SSEs.
Authors
- Jing Luo
- Xueliang Andy Sun (ORCID: https://orcid.org/0000-0003-0374-1245)
- Tsun‐Kong Sham (ORCID: https://orcid.org/0000-0003-1928-6697)
- Jiamin Fu (ORCID: https://orcid.org/0000-0002-1874-111X)
- Xiaoge Hao
- Jianwen Liang (ORCID: https://orcid.org/0000-0003-4055-1301)
- Yang Hu (ORCID: https://orcid.org/0000-0003-2731-335X)
- Shuo Wang (ORCID: https://orcid.org/0000-0002-7907-9676)
- Changhong Wang (ORCID: https://orcid.org/0000-0002-4201-0130)
- Xiaona Li (ORCID: https://orcid.org/0000-0001-6713-2997)
- Shumin Zhang (ORCID: https://orcid.org/0000-0003-2777-3938)
- Jue Liu (ORCID: https://orcid.org/0000-0002-4453-910X)
- Weihan Li (ORCID: https://orcid.org/0000-0002-6542-1784)
- Han Su
- Jian Peng (ORCID: https://orcid.org/0009-0008-0638-6326)
- Feipeng Zhao (ORCID: https://orcid.org/0000-0002-1522-6606)
- Jung Tae Kim (ORCID: https://orcid.org/0000-0001-9852-0044)
- Hui Duan (ORCID: https://orcid.org/0000-0003-3886-654X)
Institutions
- Western University (CA)
- Eastern Institute of Technology (NZ)
- Oak Ridge National Laboratory (US)
- Central South University (CN)
- China Automotive Battery Research Institute (CN)
- Grinm Advanced Materials (China) (CN)
- Ningbo Institute of Industrial Technology (CN)
Publication Details
- Journal
- Angewandte Chemie International Edition
- Published
- 2025-05-29
- DOI
- https://doi.org/10.1002/anie.202508835
- Citations
- 8
- Primary Topic
- Advanced Battery Materials and Technologies
- Type
- article
- Field-Weighted Citation Impact
- 5.84
Funders
- U.S. Department of Energy
- Canadian Light Source
- National Natural Science Foundation of China
- Natural Science Foundation of Beijing Municipality
- Canadian Institutes of Health Research
- Natural Sciences and Engineering Research Council of Canada
- National Key Research and Development Program of China
- Oak Ridge National Laboratory