Materials Data on Li2FeS2 by Materials Project
Li2FeS2 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to four S2- atoms to form LiS4 tetrahedra that share corners with six equivalent LiS6 octahedra, corners with six equivalent LiS4 tetrahedra, edges with three equivalent LiS6 octahedra, and edges with three equivalent FeS4 tetrahedra. The corner-sharing octahedra tilt angles range from 16–53°. There are three shorter (2.33 Å) and one longer (2.49 Å) Li–S bond lengths. In the second Li1+ site, Li1+ is bonded to six S2- atoms to form LiS6 octahedra that share corners with six equivalent LiS4 tetrahedra, corners with six equivalent FeS4 tetrahedra, edges with six equivalent LiS6 octahedra, edges with three equivalent LiS4 tetrahedra, and edges with three equivalent FeS4 tetrahedra. There are a spread of Li–S bond distances ranging from 2.62–2.93 Å. Fe2+ is bonded to four S2- atoms to form FeS4 tetrahedra that share corners with six equivalent LiS6 octahedra, corners with six equivalent FeS4 tetrahedra, edges with three equivalent LiS6 octahedra, and edges with three equivalent LiS4 tetrahedra. The corner-sharing octahedra tilt angles range from 18–59°. There are a spread of Fe–S bond distances ranging from 2.34–2.38 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded to four Li1+ and three equivalent Fe2+ atoms to form distorted edge-sharing SLi4Fe3 pentagonal bipyramids. In the second S2- site, S2- is bonded in a 7-coordinate geometry to six Li1+ and one Fe2+ atom.