Halide solid electrolytes with composition Li3M(III)X6 (M(III) = Lanthanides, Sc, In, X = Cl, Br, I) have been receiving renewed interest from the scientific community since 2018, after Asano et al. published that Li3YCl6 and Li3YBr6 could reach the 10 -3 S/cm ionic conductivity and showcased good performance in batteries using standard electrodes . Improved fundamental understanding of the conduction mechanism in Li3M(III)Cl6 halide solid electrolytes may help formulate design guidelines to attain comparable ionic conductivities.