DOE OSTI2020
LiFePH2O5 crystallizes in the orthorhombic Pca2_1 space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share corners with three FeO4 tetrahedra and corners with three PO4 tetrahedra. There are a spread of Li–O bond distances ranging from 1.97–2.01 Å. In the second Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share corners with three FeO4 tetrahedra and corners with three PO4 tetrahedra. There is one shorter (1.97 Å) and three longer (1.99 Å) Li–O bond length. There are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three LiO4 tetrahedra and corners with four PO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 2.02–2.06 Å. In the second Fe2+ site, Fe2+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three LiO4 tetrahedra and corners with four PO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 2.02–2.06 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three LiO4 tetrahedra and corners with four FeO4 tetrahedra. There is two shorter (1.55 Å) and two longer (1.56 Å) P–O bond length. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three LiO4 tetrahedra and corners with four FeO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.54–1.56 Å. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to one Li1+, one Fe2+, and one P5+ atom. In the second O2- site, O2- is bonded in a trigonal planar geometry to one Li1+, one Fe2+, and one P5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Li1+ and two H1+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Li1+ and two H1+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Fe2+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a trigonal planar geometry to one Li1+, one Fe2+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Fe2+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Li1+, one Fe2+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a trigonal planar geometry to one Li1+, one Fe2+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Fe2+ and one P5+ atom.