Halogen-Substituted Li₃InCl₆: Insights into the Evolved Structure, Composition, and Ionic Conductivity

Ternary Li-containing halides have gained significant interest for all-solid-state batteries because they show high Li-ion conductivity and their structures can be modified. In this study, halogen substitution in Li₃InCl₆ was attempted to form Li₃InCl_6-xX_x (X = F, Br, I) samples whose phase compositions and Li⁺ conductivity were characterized by X-ray diffraction and impedance spectroscopy. Based on the evolution of cell parameters, Cl can be substituted by F within the experimental limit of x ≤ 1.2, while by other halogens up to a solid solubility limit of x = 0.6 for Br and x < 0.1 for I. The Li-ion conductivity diminished with greater nominal compositions of X in the samples, especially as other phases exhibiting low conductivity are formed. These results suggest that increased polarizability of X is not a dominant factor that influences the Li⁺ mobility in Li₃InCl_6-xX_x.