Computational screening for novel solid-state electrolytes in Li3MX6 composition

Halide solid-state electrolytes have gained significant attention in recent years due to their high ionic conductivity, making them promising candidates for future all-solid-state batteries. Recent studies have identified numerous crystal structures with the $L{i}_{3}M{X}_6$ composition, although many remain unexplored across various chemical systems. In this research, we developed a comprehensive method to examine all conceivable space groups and structures within the $Li-M-X$ system, where M includes In, Ga, and La, and X includes F, Cl, Br, and I. Our findings revealed two metastable structures: $L{i}_{3}In{F}_6$ with $P\overline{3}c1$ symmetry and $L{i}_{3}In{I}_6$ with $C2/c$ symmetry, exhibiting ionic conductivities of 0.55 and 2.18 mS/cm at 300 K, respectively. Notably, the trigonal symmetry of $L{i}_{3}In{F}_6$ demonstrates that high ionic conductivities are not limited to monoclinic structures but can also be achieved with trigonal symmetries. The electrochemical stability windows, mechanical properties, and reaction energies of these materials with known cathodes suggest their potential for use in all-solid-state batteries. Additionally, we predicted the stability of novel materials, including $L{i}_{5}InC{l}_8$, $L{i}_{5}InB{r}_8$, $L{i}_{5}In{I}_8$, $LiI{n}_{2}C{l}_9$, $LiI{n}_{2}B{r}_9$, and $LiI{n}_2{I}_9$.