Atomic insight into Li${}^{+}$ ion transport in amorphous electrolytes Li${}_x$AlO${}_y$Cl${}_3+x-2y$ (0.5 $łeq$ x $łeq$ 1.5, 0.25 $łeq$ y $łeq$ 0.75)

Abstract

The recent study of viscoelastic amorphous oxychloride electrolytes has opened up a new field of research for solid-state electrolytes. In this work, we chose Li-Al-O-Cl system containing disordered structures with varying O/Cl ratio and Li${}^{+}$ content to study their structural characteristics and ion transport mechanism using ab-initio molecular dynamics (AIMD) simulation and machine learning interatomic potential based molecular dynamics (MLIP-based MD) simulation. It is found that O-doping results in the presence of a skeleton of Al-chains formed by AlOCl tetrahedra and the increase of glass forming ability, causing Cl atoms' rotation around centered-Al within the tetrahedron thus facilitating the motion of Li${}^{+}$ ions. However, further increase of O/Cl ratio decreases the number of rotating Cl atoms, weakening the transport of Li${}^{+}$. So increasing glass forming ability without reducing Cl content or by methods through controlling synthesis conditions, are useful to promote Li${}^{+}$ ion conducting of oxychloride electrolytes.