Exploration over Chemical Space for Stable Solid State Electrolytes with High Ion Conductivities

Chi-Hsuan Lee^1*, Chun-Wei Pao¹, Kuei-Hsien Chen²

¹Research Center for Applied Sciences, Academia Sinica, Taipei city, Taiwan
²Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei city, Taiwan

* Presenter:Chi-Hsuan Lee, email:frankreichparis@gmail.com

Lithium halides Li₃MX₆ (M = trivalent metal; X = Cl and Br) represent a promising category of solid electrolytes, exhibiting exceptional electrochemical stability and other desirable properties for all-solid-state batteries. This study aims to propose a material design strategy for lithium halides in high-voltage all-solid-state Li-ion batteries by comprehensively exploring crystal structures, phases, electronic properties, and ionic conductivities. First-principles calculations reveal the significant impact of varying compositional ratios between M and X on the structural properties and stability. The evaluation of Li-ion conductivities was conducted using ab initio molecular dynamics calculations, which were enhanced by active machine learning algorithms in advance. The mixing of Cl and Br among halogen anions results in drastic changes in the structure. Additionally, the substitution of various trivalent atoms in lithium halides leads to more distorted structures, thereby modulating the Li-ion activation energy and conductivity.

Keywords: ab initio molecular dynamics, ionic conductivity, structural properties